CA1038208A - Motor-driven screwing and transporting tool for reactor pressure vessel head retaining fastenings - Google Patents
Motor-driven screwing and transporting tool for reactor pressure vessel head retaining fasteningsInfo
- Publication number
- CA1038208A CA1038208A CA241,827A CA241827A CA1038208A CA 1038208 A CA1038208 A CA 1038208A CA 241827 A CA241827 A CA 241827A CA 1038208 A CA1038208 A CA 1038208A
- Authority
- CA
- Canada
- Prior art keywords
- stud
- nut
- gripping
- studs
- nuts
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- 238000010168 coupling process Methods 0.000 claims description 12
- 238000005859 coupling reaction Methods 0.000 claims description 12
- 230000032258 transport Effects 0.000 claims description 6
- 208000036366 Sensation of pressure Diseases 0.000 claims description 2
- 238000003780 insertion Methods 0.000 claims description 2
- 230000037431 insertion Effects 0.000 claims description 2
- GRYSXUXXBDSYRT-WOUKDFQISA-N (2r,3r,4r,5r)-2-(hydroxymethyl)-4-methoxy-5-[6-(methylamino)purin-9-yl]oxolan-3-ol Chemical compound C1=NC=2C(NC)=NC=NC=2N1[C@@H]1O[C@H](CO)[C@@H](O)[C@H]1OC GRYSXUXXBDSYRT-WOUKDFQISA-N 0.000 claims 1
- 239000012530 fluid Substances 0.000 claims 1
- 230000002093 peripheral effect Effects 0.000 claims 1
- 229920000136 polysorbate Polymers 0.000 claims 1
- 210000002832 shoulder Anatomy 0.000 description 10
- 238000007789 sealing Methods 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 6
- 238000007689 inspection Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B29/00—Accessories
- B25B29/02—Bolt tensioners
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C13/00—Pressure vessels; Containment vessels; Containment in general
- G21C13/02—Details
- G21C13/06—Sealing-plugs
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Mechanical Engineering (AREA)
- Pressure Vessels And Lids Thereof (AREA)
- Hand Tools For Fitting Together And Separating, Or Other Hand Tools (AREA)
- Fixing For Electrophotography (AREA)
- Management, Administration, Business Operations System, And Electronic Commerce (AREA)
Abstract
Abstract of the Disclosure The invention concerns a motor-driven screwing and transporting tool for tightening or loosening the threaded studs and associated tighten-ing nuts of the head bolting of pressure vessels. After the tightening nuts are loosened or before they are tightened, the weight of the studs is taken over by rotating bearings that can be lifted, so that the studs with their tightening nuts can be screwed in or out, the screw threads of the studs being thus weight-relieved. The invention is intended primarily for nuclear reactor pressure vessels.
Description
~03~2~1 Various designs of motor-driven screwing and transporting tools for tightening or loosening the head bolting of pressure vessels are known.
Such tools are known particularly for nuclear reactor pressure vessels, be-cause in the case of nuclear reactor pressure vessels the problem arises to remove and then replace a~d tighten the head of the reactor pressure vessel quickly and safely, to minimize radiation exposure of the personnel as much as possible during refueling. In nuclear reactor plants the shutdown time for refueling is influenced very substantially also by the time required for opening and closing the reactor pressure vessel. ~lere, the pressure vessel head is firmly bolted to the vessel proper via threaded studs which are sunk into the flange of the vessel, and associated tightening nuts on the upper side of the head.
A motor-driven screwing and transporting tool for loosening, trans-porting and tightening of individual tightening nuts of threaded studs is already known (German Offenlegungsschrift 2,061,037). As the loosening of individual closing or tightening nuts, the transporting and retightening in a definite order (to avoid asymmetrical stresses of the head and the pres-sure vessel) still requires relatively much time, thought has been given to the problem of pretensioning simultaneously several studs arranged in a pitch circle, to turn the associated vessel nuts up or down and to transport them forward and away. Thus, one known screw-tightening device (German Of-fenlegungsschrift 2~243,045) comprises the following elements: A support body which can be placed on the head flange, adjustably in height; tighten-ing and loosening units mounted at the support body; means at the studs and their tightening nuts for coupling the tightening and loosening units and specifically, external teeth at the tightening nuts for the engagement of the drive pinion of a nut-rotating drive of the tightening and loosening units, and teeth arranged at the head end of the threaded stud for engagement of a gripper unit, w~erein the tightening and loosening units comprise in turn the following components: A hydraulic tensioning cylinder, supported .
... . .
103BZ~8 at the support body, for axially elongating the studs by axial action on the gripping units via a power piston during the loosening or tightening of the tightening nuts: a drive for coupling and decoupling the gripper body rela-tive to the studs as well as said nut-turning drive with a drive pinion for turning the tightening nut in the direction of screwing it on or off via its external gearing.
Beyond this, it has also been proposed already to improve a motor-driven screwing and transporting tool of the kind described by loosening or tightening, as far as possible, all the tightening nuts of a head bolting, 1~ as well as transporting them to and fro, simultaneously. In this older arrangement, hydraulic plungers are already attached at the screwing and transporting tool, by means of which the distance of the tool from the sur-face of the head can be adjusted in accordance with the progress of the un-screwing and screwing operation.
The present invention is based on the consideration that it is de-sirable in pressure vessels in general, and in reactor pressure vessels in particular, to not only loosen, retighten and transport the tightening or closing nuts of the head bolts, as far as possible, automatically and in large numbers, but to include also the studs themselves in the operations, as then a number of important advantages with respect to time and space sa-vings as well as safety for the operating personnel ar0 obtained.
According to the present invention there is provided a device for securing or releasing a connector capable of connecting a first member to a second member, ~he connector comprising a stud having a threaded end region and a threaded intermediate region, and an adjusting nut on the threaded intermediate region, the arrangement being such that, during connection, the stud extends through an aperture in the second member and is located at its threaded end region in a threaded hole in the first member, with the adjust-ing nut on that side of the second member remote from the first member and urging the second member towards the first member; the device comprising:
Such tools are known particularly for nuclear reactor pressure vessels, be-cause in the case of nuclear reactor pressure vessels the problem arises to remove and then replace a~d tighten the head of the reactor pressure vessel quickly and safely, to minimize radiation exposure of the personnel as much as possible during refueling. In nuclear reactor plants the shutdown time for refueling is influenced very substantially also by the time required for opening and closing the reactor pressure vessel. ~lere, the pressure vessel head is firmly bolted to the vessel proper via threaded studs which are sunk into the flange of the vessel, and associated tightening nuts on the upper side of the head.
A motor-driven screwing and transporting tool for loosening, trans-porting and tightening of individual tightening nuts of threaded studs is already known (German Offenlegungsschrift 2,061,037). As the loosening of individual closing or tightening nuts, the transporting and retightening in a definite order (to avoid asymmetrical stresses of the head and the pres-sure vessel) still requires relatively much time, thought has been given to the problem of pretensioning simultaneously several studs arranged in a pitch circle, to turn the associated vessel nuts up or down and to transport them forward and away. Thus, one known screw-tightening device (German Of-fenlegungsschrift 2~243,045) comprises the following elements: A support body which can be placed on the head flange, adjustably in height; tighten-ing and loosening units mounted at the support body; means at the studs and their tightening nuts for coupling the tightening and loosening units and specifically, external teeth at the tightening nuts for the engagement of the drive pinion of a nut-rotating drive of the tightening and loosening units, and teeth arranged at the head end of the threaded stud for engagement of a gripper unit, w~erein the tightening and loosening units comprise in turn the following components: A hydraulic tensioning cylinder, supported .
... . .
103BZ~8 at the support body, for axially elongating the studs by axial action on the gripping units via a power piston during the loosening or tightening of the tightening nuts: a drive for coupling and decoupling the gripper body rela-tive to the studs as well as said nut-turning drive with a drive pinion for turning the tightening nut in the direction of screwing it on or off via its external gearing.
Beyond this, it has also been proposed already to improve a motor-driven screwing and transporting tool of the kind described by loosening or tightening, as far as possible, all the tightening nuts of a head bolting, 1~ as well as transporting them to and fro, simultaneously. In this older arrangement, hydraulic plungers are already attached at the screwing and transporting tool, by means of which the distance of the tool from the sur-face of the head can be adjusted in accordance with the progress of the un-screwing and screwing operation.
The present invention is based on the consideration that it is de-sirable in pressure vessels in general, and in reactor pressure vessels in particular, to not only loosen, retighten and transport the tightening or closing nuts of the head bolts, as far as possible, automatically and in large numbers, but to include also the studs themselves in the operations, as then a number of important advantages with respect to time and space sa-vings as well as safety for the operating personnel ar0 obtained.
According to the present invention there is provided a device for securing or releasing a connector capable of connecting a first member to a second member, ~he connector comprising a stud having a threaded end region and a threaded intermediate region, and an adjusting nut on the threaded intermediate region, the arrangement being such that, during connection, the stud extends through an aperture in the second member and is located at its threaded end region in a threaded hole in the first member, with the adjust-ing nut on that side of the second member remote from the first member and urging the second member towards the first member; the device comprising:
- 2 -. .
103B2~1~
a support whicll is intended to be adjustable parallel to the axis of the stud, and, carried by the support: (1) means for gripping an end region of the stud remote from the said threaded end region; (2) means for axially extending the stud; (3) first drive means for rotating the adjusting nut relative to the stud; (4) second drive means for screwing and unscrewing the stud (and the adjusting nut carried thereon) relative to the first member; and (5) lifting means for ~aking up the weight of the stud and ad-justing nut whilst they are being acted upon by the second drive means.
A preferred embodiment of the invention comprises a device for unscrewing and screwing nuclear reactor pressure vessel head-retaining nuts and screw studs, the studs extending upwardly through stud holes in a head flange of a removable head of a reactor pressure vessel, the studs having threaded lower ends screwed in~o threaded holes in the pressure vessel's top and threaded portions on which the nuts are screwed above the head flange to hold down the head on the pressure vessel with the studs under pretension between the vessel's top and the nuts, the nuts having external gear teeth for their rotation and the studs having upper ends spaced above the nuts; said device comprising a support body and means for supporting said body at controllable heights on said head flange; and unscrewing and screwing units for said nuts and studs, mounted on said body and having axial passages for releasable insertion of the studs and nuts; each of said units for a stud and nut when inserted in the unit's passage, having a pinion releasably meshing with the nut's said gear teeth and means for reversingly driving said pinion for unscrewing and screwing movements of the nut on the stud, gripping means for releasably gripping the upper end of the stud above :
the nut, and means for applying upward force to said gripping means for stretching the stud upwardly from the pressure vessel's top to free the nut from said pretension during said movements; each of said units further having means for releasably engaging and reversibly rotating the stud so its -said lower end can be unscrewed and screwed in the threaded hole in the -~
~ _ 3 _ pressure vessel's top while the nut remains screwed on the stud, and means for applying a lifting force to both the nut and stud to relieve the stud's said lower end from the weight of the nut and stud while being unscrewed and screwed in the pressure vessel's threaded hole.
The advantages attainable with the invention are essentially the following: The threaded studs of a reactor pressure vessel can now be screwed out of the lower part of the reactor pressure vessel for each re-fueling. This permits in-service inspection of the studs at a suitable storage location away from the reactor pressure vessel as well as in-service tests of the tapped holes in the lower part of the reactor pressure vessel, which have become accessible after the studs are removed. Sealing the tapped holes in the lower part of the reactor pressure vessel is easier than seal-ing screws which remain in the lower part. The motor-driven screwing and transporting tool according to the invention requires a minimum of personnel for moving the studs and nuts, i.e., for unscrewing and screwing. The transporting of ~he threaded studs with their tightening nuts is possible in a highly mechanized and therefore, time saving manner. In newly-to-be-built nuclear - 3a _ Z~
reactor plants, the level of the llpper edge of tlle reactor room can be low-ered, as throug~ the removal of the studs, the cross-traveling height for the refueling machine is reduced. Through such a lowering of the level of the upper edge of the reactor room, the amount of flooding water required is reduced.
It is particularly advantageous if the tool is arranged for sim-ultaneously unscrewing the threaded studs and the tightening nuts mounted on them, after the latter have been loosened, and for simultaneously screwing-in the studs and their tightening nuts before the latter are tighten0d, and that to this end the tightening nut can be secured at the threaded stud in such a manner that rotation of the tightening nut relative to the stud be-yond a predeterminable screw-in ready position or a predeterminable readiness position rotation angle range is prevented in both directions of rotation.
Cne preferred embodiment of the invention provides that the tool for the simultaneous tightening or loosening of all the bolting positions arranged -on the pitch circle of the head bolting, comprises one tightening and loosen-ing unit each for each threaded stud with tightening nut. One thereby avoids belt or chain drives, and the direct coupling of the drive motors is opera-tionally reliable and without problems.
According to a further embodiment, the invention provides that the tool is arranged for transporting to and fro the unscrewed studs together with the tightening nuts mounted on them and can be brought into engagement for this purpose by means of support surfaces of its tightening and loosening units with corresponding counter-support surfaces of the stud. These support and counter-support surfaces are advantageously identical with the engagement surfaces by which the power piston of the hydraulic tensioning cylinders and the gripper body for turning the respective stud are in mutual engagement.
If the tool according to the invention is equipped with a gripper body which can be screwed on the thread on the head side of the stud and is designed as a gripping nut with external teeth~ then it is particularly advantageous l03sza~
if the lifting and s-~lpport means comprise a lifting cylinder, arranged con-centrically with the screwed-on gripping nut, with a lifting piston and a thrust bearing, wherein the lifting piston with an internal shoulder can be brought into engagement, via the thrust bearing, with an external shoulder of the gripping nut against the force of gravity. In this manner, the weights of the studs can be balanced hydraulically or pneumatically in fine dosages, and the thrust bearing provides advantageous rolling friction for the weight-compensated stud, so that the rotation drive for the stud has to supply re_ latively small torques. In this connection, a further embodiment of the tool, which has single-action tensioning pistons, provides that the lifting cylinder is arranged so as to follow the hydraulic tensioning cylinders in the axial direction and that the lifting piston is double-acting and can be brought into contact with the tensioning pistons as the resetting piston - of the tensioning pistons in the direction opposed to that of its lifting direction. The multiple, and preferably double arrangement of hydraulic tensioning cylinders ~nd associated power pistons in tandem is known per se ; from the German Auslegeschrift 1,271,050; this has the advantage that large lifting and tensioning forces can be obtained with a relatively small dia-meter.
An example of an embodiment of the invention is illustrated in the accompanying drawings, in which:
Figure 1 is a vertical cross section of a portion of a reactor pressure vessel and its removable head and of one of the head-retaining studs and nuts;
Figure 2 is a vertical cross section on a scale enlarged over Fig-ure 1, showing a head-retaining stud with the tightening nut which is still screwed onto the stud, and on which the tightening and loosening unit of the motor-driven screwing and transporting tool according to this invention is placed;
Figure 3 is a partial cross section taken on the line III-III in Figure 2; 10~8 Figure 4 is a cross section taken on the line IV-IV in Figure 2;
Figure 5 is a top view of the example, showing the annular support body and three of the series of tightening and loosening units which side-by-side extend throughout the circumference of the support body; and Figure 6 is a vertical section of an individual lifting device, three of which are required to adjust the height of the tool.
The head bolting, shown in a partial view of Figure 1, of a nuclear ~;
reactor pressure vessel (called RPV for short in the following) has a lower RPV part 1, to which the RPV head 2 is bolted tightly. For this purpose, two concentric sealing rings 4 are placed in circular slots 3 of the head 2, and threaded studs 6 are screwed by their lower threads 6.1 into the ap-propriate tapped holes 5; the stud shanks go through the head in appropriate head holes 2.1 and the head 2 is now clamped to the lower part 1 by the studs 6 and the tightening nuts 6.2 on spherical washers 6.3, in a sealed manner, as mentioned. To this end, the tightening nut 6.2 holds on the thread 6.4 of the stud 6, the shank of the stud 6 being subjected to an axial preten-sioning force, which is about 765 ~X 103 kg per stud in the embodiment example shown. As will be explained later, the studs 6 are axially elongated hydrau-lically so that this pretensioning force can be attained, and in the elon-gated condition the tightening nuts 6.2 are then tightened, and for loosening the head bolting, the studs must also be stretched axially, of course, so that the tightening nuts 6.2 can be loosened. The maximum hydraulic pre-tensioning force per screw is about 900 ~ 103 kg. It is ensured by the above-mentioned large residual pretensioning forces that in the area of the seals 4 the required contact pressure for sealing the RPV is achieved. Even though only one stud is shown in Figure 1, it is understood that for the head bol-ting of an RPV a multiplicity of such screws is provided which are arranged on a so-called pitch circle; in the embodiment example shown, there are 52 studs with the corresponding tightening nuts 6.2, holes 2.1 in the head :., ' .,, ~03~Z(~B
flan~e 2.2 and tapped holes 5.
Figure 2 in conjunction with Figure S now shows the details of the motor-driven screwing and transporting tool for tighteni~g or loosening the head bolting of a pressure vessel, particularly an RPV, which comprises the studs 6 and associated tightening nuts 6.2. The tool comprises, first of all, an annular support body 7 which can be placed, adjustable in height, on the head flange 1 and has in the case shown a basically circular shape so as to match the pitch circle of the studs 6. At the support body 7 are disposed tightening and loosening unit5 8, by means of which the support body 7 can be placed on the respective studs 6 with tightening nuts 6.2; see par-ticularly Figure 5.
Figure 2 shows one of the tightening and loosening units 8 which is put over a stud 6 with the tightening nut 6.2. Here, the tightening process for the stud 6 may have just been completed, or it could be just before the loosening process is started. The means at the studs 6 and their tighten-ing nuts 6.2 for coupling the tightening and loosening units 8, comprise external gear teeth 6.5 on the tightening nuts 6.2 for the engagement of the drive pinion 9 of a nut-turning drive 10, and a thread 11 at the head end of the stud (see also Figure 1) for the engagement of a gripper body 12, designed in the case shown as a gripping nut, In principle, otller suitable gripping bodies may also be used instead of a gripping nut, e.g., two grip-per jaws which can be brought into engagement hydraulically or pneumatically from two opposite sides with teeth or with circular slots and circular shoul-ders at the upper end of the stud 6, not shown here but as is known per se from Offenlegungsschrift 2,243,045. The gripping nuts shown, however, are particularly advantageous, as they fit in with the system of the tightening and loosening units particularly well, The gripping nuts have an internal thread 12.1 for the stud thread 11.
Each of the tightening and loosening units 8 comprises the follow-ing components: Hydraulic tensioning cylinders 13, mounted on the annular l03s2a~
support body 7, for axially elongating the studs 6 by axial action on thegripping nuts 12, via power pistons 13.1, during the loosening or tightening of the tightening nuts 6.2. Two hydraulic tensioning cylinders 13 in tandem with the respective power pistons 13.1 are shown, whereby twice the tension-ing force can be obtained with a given diameter, as compared to only one tensioning cylinder, for a given hydraulic pressure. The annular power pis-tons 13.1 surround the shank of the studs 6, and the upper power pistons 13.1 attacks via a spherical washer 12.4 at a spherically bevelled shoulder 12.2 of the gripping nut 12, the spherical washer 12.4 being held at the 10 spherical shoulder 12.2 of the gripping nut by means of screws 12.3 distri- ;~
buted over the circumference of the former. It is achieved thereby that the power pistons exert their pressure forces completely symmetrically on the gripping nut 12. ~ :
The tightening and loosening units 8 further comprise a drive 14 for coupling and decoupling the gripping nut 12 relative to the stud 6, with a drive pinion 14.1, which is mounted, secured against rotation, by means of the key 14.3 and the end thread 14.3', on the shaft 14.2; with a transmission unit 14.4 and the drive motor 14.5 proper, whose shaft, indi-cated at 15.5', is coupled with the shaft 14.4' of the transmission unit 14, for instance, via miter gears (not shown). The transmission unit 14 further contains a friction clutch, not shownJ so that the drive pinion 14.1 is de-coupled from the drive motor 14.5 if a maximum torque is exceeded, and the motor 14.5 idles. This is the case if the gripping nut 12 if fully tight.
Instead of an electric motor 14.5, a hydraulic motor with associated pump or a pneumatic drive ~not shown) can also be used. The drive pinion 14.1 meshes, as will be seen, with the external teeth 12.5 of the gripping nut 12.
The mounting flange 14.6 of the transmission unit 14 is attached to the lift-ing piston 15 and is axially movable with the latter, as will be further explained below.
103B2~1~
a support whicll is intended to be adjustable parallel to the axis of the stud, and, carried by the support: (1) means for gripping an end region of the stud remote from the said threaded end region; (2) means for axially extending the stud; (3) first drive means for rotating the adjusting nut relative to the stud; (4) second drive means for screwing and unscrewing the stud (and the adjusting nut carried thereon) relative to the first member; and (5) lifting means for ~aking up the weight of the stud and ad-justing nut whilst they are being acted upon by the second drive means.
A preferred embodiment of the invention comprises a device for unscrewing and screwing nuclear reactor pressure vessel head-retaining nuts and screw studs, the studs extending upwardly through stud holes in a head flange of a removable head of a reactor pressure vessel, the studs having threaded lower ends screwed in~o threaded holes in the pressure vessel's top and threaded portions on which the nuts are screwed above the head flange to hold down the head on the pressure vessel with the studs under pretension between the vessel's top and the nuts, the nuts having external gear teeth for their rotation and the studs having upper ends spaced above the nuts; said device comprising a support body and means for supporting said body at controllable heights on said head flange; and unscrewing and screwing units for said nuts and studs, mounted on said body and having axial passages for releasable insertion of the studs and nuts; each of said units for a stud and nut when inserted in the unit's passage, having a pinion releasably meshing with the nut's said gear teeth and means for reversingly driving said pinion for unscrewing and screwing movements of the nut on the stud, gripping means for releasably gripping the upper end of the stud above :
the nut, and means for applying upward force to said gripping means for stretching the stud upwardly from the pressure vessel's top to free the nut from said pretension during said movements; each of said units further having means for releasably engaging and reversibly rotating the stud so its -said lower end can be unscrewed and screwed in the threaded hole in the -~
~ _ 3 _ pressure vessel's top while the nut remains screwed on the stud, and means for applying a lifting force to both the nut and stud to relieve the stud's said lower end from the weight of the nut and stud while being unscrewed and screwed in the pressure vessel's threaded hole.
The advantages attainable with the invention are essentially the following: The threaded studs of a reactor pressure vessel can now be screwed out of the lower part of the reactor pressure vessel for each re-fueling. This permits in-service inspection of the studs at a suitable storage location away from the reactor pressure vessel as well as in-service tests of the tapped holes in the lower part of the reactor pressure vessel, which have become accessible after the studs are removed. Sealing the tapped holes in the lower part of the reactor pressure vessel is easier than seal-ing screws which remain in the lower part. The motor-driven screwing and transporting tool according to the invention requires a minimum of personnel for moving the studs and nuts, i.e., for unscrewing and screwing. The transporting of ~he threaded studs with their tightening nuts is possible in a highly mechanized and therefore, time saving manner. In newly-to-be-built nuclear - 3a _ Z~
reactor plants, the level of the llpper edge of tlle reactor room can be low-ered, as throug~ the removal of the studs, the cross-traveling height for the refueling machine is reduced. Through such a lowering of the level of the upper edge of the reactor room, the amount of flooding water required is reduced.
It is particularly advantageous if the tool is arranged for sim-ultaneously unscrewing the threaded studs and the tightening nuts mounted on them, after the latter have been loosened, and for simultaneously screwing-in the studs and their tightening nuts before the latter are tighten0d, and that to this end the tightening nut can be secured at the threaded stud in such a manner that rotation of the tightening nut relative to the stud be-yond a predeterminable screw-in ready position or a predeterminable readiness position rotation angle range is prevented in both directions of rotation.
Cne preferred embodiment of the invention provides that the tool for the simultaneous tightening or loosening of all the bolting positions arranged -on the pitch circle of the head bolting, comprises one tightening and loosen-ing unit each for each threaded stud with tightening nut. One thereby avoids belt or chain drives, and the direct coupling of the drive motors is opera-tionally reliable and without problems.
According to a further embodiment, the invention provides that the tool is arranged for transporting to and fro the unscrewed studs together with the tightening nuts mounted on them and can be brought into engagement for this purpose by means of support surfaces of its tightening and loosening units with corresponding counter-support surfaces of the stud. These support and counter-support surfaces are advantageously identical with the engagement surfaces by which the power piston of the hydraulic tensioning cylinders and the gripper body for turning the respective stud are in mutual engagement.
If the tool according to the invention is equipped with a gripper body which can be screwed on the thread on the head side of the stud and is designed as a gripping nut with external teeth~ then it is particularly advantageous l03sza~
if the lifting and s-~lpport means comprise a lifting cylinder, arranged con-centrically with the screwed-on gripping nut, with a lifting piston and a thrust bearing, wherein the lifting piston with an internal shoulder can be brought into engagement, via the thrust bearing, with an external shoulder of the gripping nut against the force of gravity. In this manner, the weights of the studs can be balanced hydraulically or pneumatically in fine dosages, and the thrust bearing provides advantageous rolling friction for the weight-compensated stud, so that the rotation drive for the stud has to supply re_ latively small torques. In this connection, a further embodiment of the tool, which has single-action tensioning pistons, provides that the lifting cylinder is arranged so as to follow the hydraulic tensioning cylinders in the axial direction and that the lifting piston is double-acting and can be brought into contact with the tensioning pistons as the resetting piston - of the tensioning pistons in the direction opposed to that of its lifting direction. The multiple, and preferably double arrangement of hydraulic tensioning cylinders ~nd associated power pistons in tandem is known per se ; from the German Auslegeschrift 1,271,050; this has the advantage that large lifting and tensioning forces can be obtained with a relatively small dia-meter.
An example of an embodiment of the invention is illustrated in the accompanying drawings, in which:
Figure 1 is a vertical cross section of a portion of a reactor pressure vessel and its removable head and of one of the head-retaining studs and nuts;
Figure 2 is a vertical cross section on a scale enlarged over Fig-ure 1, showing a head-retaining stud with the tightening nut which is still screwed onto the stud, and on which the tightening and loosening unit of the motor-driven screwing and transporting tool according to this invention is placed;
Figure 3 is a partial cross section taken on the line III-III in Figure 2; 10~8 Figure 4 is a cross section taken on the line IV-IV in Figure 2;
Figure 5 is a top view of the example, showing the annular support body and three of the series of tightening and loosening units which side-by-side extend throughout the circumference of the support body; and Figure 6 is a vertical section of an individual lifting device, three of which are required to adjust the height of the tool.
The head bolting, shown in a partial view of Figure 1, of a nuclear ~;
reactor pressure vessel (called RPV for short in the following) has a lower RPV part 1, to which the RPV head 2 is bolted tightly. For this purpose, two concentric sealing rings 4 are placed in circular slots 3 of the head 2, and threaded studs 6 are screwed by their lower threads 6.1 into the ap-propriate tapped holes 5; the stud shanks go through the head in appropriate head holes 2.1 and the head 2 is now clamped to the lower part 1 by the studs 6 and the tightening nuts 6.2 on spherical washers 6.3, in a sealed manner, as mentioned. To this end, the tightening nut 6.2 holds on the thread 6.4 of the stud 6, the shank of the stud 6 being subjected to an axial preten-sioning force, which is about 765 ~X 103 kg per stud in the embodiment example shown. As will be explained later, the studs 6 are axially elongated hydrau-lically so that this pretensioning force can be attained, and in the elon-gated condition the tightening nuts 6.2 are then tightened, and for loosening the head bolting, the studs must also be stretched axially, of course, so that the tightening nuts 6.2 can be loosened. The maximum hydraulic pre-tensioning force per screw is about 900 ~ 103 kg. It is ensured by the above-mentioned large residual pretensioning forces that in the area of the seals 4 the required contact pressure for sealing the RPV is achieved. Even though only one stud is shown in Figure 1, it is understood that for the head bol-ting of an RPV a multiplicity of such screws is provided which are arranged on a so-called pitch circle; in the embodiment example shown, there are 52 studs with the corresponding tightening nuts 6.2, holes 2.1 in the head :., ' .,, ~03~Z(~B
flan~e 2.2 and tapped holes 5.
Figure 2 in conjunction with Figure S now shows the details of the motor-driven screwing and transporting tool for tighteni~g or loosening the head bolting of a pressure vessel, particularly an RPV, which comprises the studs 6 and associated tightening nuts 6.2. The tool comprises, first of all, an annular support body 7 which can be placed, adjustable in height, on the head flange 1 and has in the case shown a basically circular shape so as to match the pitch circle of the studs 6. At the support body 7 are disposed tightening and loosening unit5 8, by means of which the support body 7 can be placed on the respective studs 6 with tightening nuts 6.2; see par-ticularly Figure 5.
Figure 2 shows one of the tightening and loosening units 8 which is put over a stud 6 with the tightening nut 6.2. Here, the tightening process for the stud 6 may have just been completed, or it could be just before the loosening process is started. The means at the studs 6 and their tighten-ing nuts 6.2 for coupling the tightening and loosening units 8, comprise external gear teeth 6.5 on the tightening nuts 6.2 for the engagement of the drive pinion 9 of a nut-turning drive 10, and a thread 11 at the head end of the stud (see also Figure 1) for the engagement of a gripper body 12, designed in the case shown as a gripping nut, In principle, otller suitable gripping bodies may also be used instead of a gripping nut, e.g., two grip-per jaws which can be brought into engagement hydraulically or pneumatically from two opposite sides with teeth or with circular slots and circular shoul-ders at the upper end of the stud 6, not shown here but as is known per se from Offenlegungsschrift 2,243,045. The gripping nuts shown, however, are particularly advantageous, as they fit in with the system of the tightening and loosening units particularly well, The gripping nuts have an internal thread 12.1 for the stud thread 11.
Each of the tightening and loosening units 8 comprises the follow-ing components: Hydraulic tensioning cylinders 13, mounted on the annular l03s2a~
support body 7, for axially elongating the studs 6 by axial action on thegripping nuts 12, via power pistons 13.1, during the loosening or tightening of the tightening nuts 6.2. Two hydraulic tensioning cylinders 13 in tandem with the respective power pistons 13.1 are shown, whereby twice the tension-ing force can be obtained with a given diameter, as compared to only one tensioning cylinder, for a given hydraulic pressure. The annular power pis-tons 13.1 surround the shank of the studs 6, and the upper power pistons 13.1 attacks via a spherical washer 12.4 at a spherically bevelled shoulder 12.2 of the gripping nut 12, the spherical washer 12.4 being held at the 10 spherical shoulder 12.2 of the gripping nut by means of screws 12.3 distri- ;~
buted over the circumference of the former. It is achieved thereby that the power pistons exert their pressure forces completely symmetrically on the gripping nut 12. ~ :
The tightening and loosening units 8 further comprise a drive 14 for coupling and decoupling the gripping nut 12 relative to the stud 6, with a drive pinion 14.1, which is mounted, secured against rotation, by means of the key 14.3 and the end thread 14.3', on the shaft 14.2; with a transmission unit 14.4 and the drive motor 14.5 proper, whose shaft, indi-cated at 15.5', is coupled with the shaft 14.4' of the transmission unit 14, for instance, via miter gears (not shown). The transmission unit 14 further contains a friction clutch, not shownJ so that the drive pinion 14.1 is de-coupled from the drive motor 14.5 if a maximum torque is exceeded, and the motor 14.5 idles. This is the case if the gripping nut 12 if fully tight.
Instead of an electric motor 14.5, a hydraulic motor with associated pump or a pneumatic drive ~not shown) can also be used. The drive pinion 14.1 meshes, as will be seen, with the external teeth 12.5 of the gripping nut 12.
The mounting flange 14.6 of the transmission unit 14 is attached to the lift-ing piston 15 and is axially movable with the latter, as will be further explained below.
3~ Part of the tightening and loosening unit 8 is further the nut-, ' ~
103~2~B
turning drive 10 with the drive pinion 9 which serves to turn the tightening nut 6.2 via its external gearing 6.5 in the screw-on and screw-off direction.
The nut drive 10 is designed similar to the drive 14. The drive pinion 9, whose gear teeth g.1 mesh with the external gear teeth 6.5 of the tightening nut 6.2, is supported on the shaft 10.1 spring-loaded in the axial direction, so that the engagement of the teeth 9.1 with the teeth 6.5 is facilitated when the tightening and loosening unit 8 is put in place, and jamming is avoided. To this end, there is securely mounted on the shaft 10.1 the washer 10.2, against which the helical compression spring 10.3 is braced and the drive pinion 9 pushes axially against a snap ring 10.~. The electric motor is designated with 10.5 and the transmission unit with 10.6. The transmis_ sion unit 10.6 is attached to the support body 7, for instance, via a U-shaped holder 10.7. 10.8 is a protective sheet-metal cover which is bolted to the support body 7 and covers the drive pinion 9 at the top.
For screwing the threaded studs 6 into and out of the tapped holes 5 of the lower RPV part 1 (see Figure 1), the tightening and loosening units -~
8 are now provided with lifting and support means 15, 16 which can be switch-ed into and out of engagement relative to the studs 6, to provide a support which is rotatable and in the process weight-relieves the screw threads 6.1, -5 of the stud 6 and the pressure vessel 1, respectively, associated with each other at the base end, and the tightening and loosening units 8 further comprise a rotation drive 17 which can be brought into engagement with the studs 6 in a positively force-transmitting manner. The weight of an indivi-dual stud 6 with the tightening nut 6.2 and the gripping nut 12 in the RPV
shown, which is laid out for a power of 1200 MWel, is about 2 tons or mega-ponds (2000 kg). The lifting means 15 are therefore employed for the screw-ing-in or out of the threaded studs 6 to generate a force compensating this weight, so that seizing between the screw threads 6.1, 5 is reliably pre-vented, the support means 16 providing for low friction, preferably rolling friction.
_ g _ . . , ~0:182~8 In detail, the lifting an~ support means 15, 16 are comprised of a lifting cylin~er 15.1, which is arranged concentrically to the screwe~-on gripping nut 12 and in whicll the annular lifting piston 15.2 is disposed, and of a thrust bearing 16, where the lif~ing piston 15.2 with an inner shoulder 15.3 ran be brought into engagement with an outer shoulder 12.6 of the gripping nut 12 via the thrust bearing 16 against the direction of the force of gravity. As will be seen, the lifting cylinder 15.1 is arran-ged axially following the hydraulic tensioning cylinder 13, i.e., is flanged to the upper tensioning cylinder 13, and the lifting piston 15.2 is of double- ~ ~
action design, two hydraulic feed lines being indicated by the dash-dotted ~-lines 15.21, 15.22. The lifting piston 15.2 can therefore be acted upon due `
to its piston shoulder 15.3, which represents the effective hydraulic area, deflected upward via the line 15.21, or downward if acted upon via the line -15.22. rhe upward movement is limited by the stop ring 15.24, which is fas-tened at the upper circumference of the cylinder 15.1 on its inner side rela-tive to the annular support 7. Sealing rings placed in slots are designa-; ted with 15.4 in the arrangement 15. The lower piston shoulder 15.3 can be ~ -brought to a stop with the upper of the power pistons 13.1, as can be seen, and can therefore serve as a restoring pressure piston for the power pistons 13.1 in the direction opposed to its lifting direction. The liting piston 15.2 therefore has a dual function; for one, the weight relief of the parts previously noted, and secondly, the restoring function of these parts.
At the outer circumference of the lifting piston 15.2 there is fastened in an area left free by the lifting cylinder 15.1, the already men-tioned drive motor 14 for the gripping nut 12, whose pinion 14.1 goes through the lifting piston 15.2 in a slot 15.25 to mesh with the gripping nut 12~
Similarly, also the annular support frame 14.7 of the motor 14 is slotted at this point (slot 14.71). To take up the reaction torque of the drive `~
motor 14, the annular frame 14.7, which is welded to the lifting piston 15.2, is guided in the axial direction by the guide bar 18, which is attached at 10382~8 the lifting cylinder 15~1 at 18.1 and 18.2. For this purpose, the annular frame 14.7 has a radially-directed guide bracket 14.8 of U-shaped cross sec-tion (see Figure 3).
The rotation drive 17 is fastened to the support body 7 and is pre-ferably a pneumatically energized drive-screw motor, whose drive pinion 17.1 is in engagement with a coupling member 19 which can be engaged and disen-gaged relative to the stud 6, the teeth 17.2 meshing with the external teeth 19.1 of the coupling member 19. To this end, the drive pinion 17.1 goes through the support body 7 in a slot 7.1 and the sleeve 20 inserted at the inside circumference of the support body 7, in a slot 20.1. The drive pin-ion 17.1 is mounted on the shaft 17.2, secured against rotation, which latter is supported in bearing elements 17.3 which are arranged at an axial distance from each other. ~le housing of the drive 17 is designated with 17.5; it contains the drive-screw motor proper, whose pneumatic feed lines are not visible.
The coupling member 19 is formed by a hollow cylindrical driving disk, for instance, which is supported concentrically and rotatably with respect to the stud 6 and axially spring-loaded in the support body housing, ; i.e., in the sleeve 20, with the external teeth 19.1 and internal teeth 19.2, which can be engaged with corresponding coupling projections and recesses 21.1, 21.2 of a driving ring 21 which is connected with the stud 6, secure against rotation, although displaced longitudinally. ~le axially spring loaded and rotatable support of the driving disk 19 is achieved by the thrust bearing 19.3 which rests via a support ring 19.4 and a helical compression spring 19.5 against a counter-support ring 19.6 with a retaining ring 19.7.
If therefore the tightening and loosening units 8 are put over the respec-tive associated stud 6, then the driving dis~ 19 can give way resiliently in the axial direction until its teeth 19.2 engage with the mating te~th 21.1, 21.2. A retaining ring for the sleeve 20 is designated with 20.2.
The sleeve is furthermore pinned at 20.3 in the support body 7.
1038Z~E~
~le entire screwing and transporting tool, i.e., its respective tightening and loosening units 8, are now arranged for simultaneously screwing-out the studs 6 and the tightening nuts 6.2 sitting on them after the latter have been loosened, and for simultaneously screwing-in the studs 6 and their tightening screws 6.2 before the latter are tightened. For this purpose, the tightening nut 6.2 can be locked to the stud 6 in such a manner that rotation of the tightening nut 6.2 relative to the stud 6 beyond a preselectable screwing-on readiness position or a preselectable readiness-position rotation angle range, is prevented in both directions of rotation.
For this purpose, the driving ring 21 has, at its end facing the tightening nut 6.2, a projection 21.3 with a stop surface pointing in the circumferen-tial direction, and the tightening nut 6.2 is provided at its upper end face with a latch 6.8. This latch 6.8 can be attached at the end face of the tightening nut adjusted in such a manner that the nut 6.2, after traveling through a screw-off rotation angle which is equal to or larger than the angle of rotation required for loosening the nut 6.2 during the axial elon-gation of the stud 6, runs against the stop surface 21.3 with its latch 6.8.
In the case shown in Figure 2, the tightening nut 6.2 is still tight. If it is, therefore, stretched axially by the tensioning cylinder 13 and piston 13.1, and if the tightening nut 6.2 is turned by the drive pinion 9 counter-clockwise, then the tight0ning nut 6.2 can travel through a screwing-off rotation angle which amounts to one full revolution, minus the arc of the projection 21.3 of the driving ring 21. This means, the pitch of the stud and tightening nut thread is chosen accordingly. In the present case, the thread is a metric thread M210 x 8. The pitch of 8 mm per thread is there-fore sufficient for unscrewing the tightening nut 6.2, from which it is con-cluded that the axial elongation of the stud 6 in the permanent condition must be somewhat less than 8 mm. The driving ring 21 is designed as a separate part, which is, for instance, shrunk onto a corresponding shoulder 3~ 6.9 of the stud. This is advantageous because a certain amount of wear 103~Z~I~
takes place at the part 21. i~owever, the invention is not limited to this;
special threaded stu~s can also ~e used whîch have an integrally formed driving ring 21.
The engagement between the latch 6.8 and the stop surface 2l.3 as well as between tlle driving disk l9 and the driving ring 21 is illustra-ted once more in the cross-sectional view according to Figure ~.
As shown particularly in Figure 5> the tool according to the in-vention for the simultaneous tightening or loosening of all the screw con-nections arranged in the pitch circle 22 of the pressure vessel's head bol-ting, is equipped with one tightening and loosening unit 8 for each stud 6 with tightening nut 6.2. The tool is furthermore arranged for transporting to and fro the loosened studs 6 including the tightening nuts 6.2 sitting on them, and for this purpose can be brought into engagement, by means of support surfaces 13.11 of their tightening and loosening units 8, with corresponding counter support surfaces 12.41 of the stud 6. As will be seen, the support and countersupport surfaces 13.11, 12.41 are identical with the contact surfaces with which the power piston 13.1 of the hydraulic tension-ing cylinders 13 and the gripping nut 12 for stretching the stud 6, are in mu*ual engagement.
During the hydraulic elongation of the stud 6, the elongation can be read at a dial gage 22, whose plunger 22.1 rests against the reference surface 23.1 of a measuring pin 23. This measuring pin 23, with which every stud 6 is providedJ extends through a hole 23.2 into the interior of the stud 6 and therefore does not participate in the elongation of the stud 6.
The mounting nuts for holding the dial gage 22 are designated with 22.2 and 22.3.
The bracket 24 serves, as known per se, for the purpose of securing ; against rotation. With its two angled-off ends, which make contact with the end face of the gripping nut 12, it is secured by the pin 24.1 and the threaded bolt 24.2. It prevents the gripping nut 12 from being turned off .... . . .
:
~03~2(~1~
during the movement of the stud 6.
Witll 25 is designated as a whole a high-pressure hydraulic feeding arrangement. A hydraulic ring line, not visible, leads to the individual shut-off device 25.1 and from there via the line 25.2 and the distributor head 25.3 as well as the lines 25.4 to the two tensioning cylinders 13, which are provided with corresponding hydraulic canals 13.3. Corresponding sealing rings between the piston 13.1 and the cylinders 13 are designated as a whole with 13.4. Oil-leak monitoring canals carry the reference symbol 13.5. The escape of leakage oil can be recognized at transparent, screwed-in caps 13.51.
The mounting frame 25.5 for the hydraulic device 25 is bolted to the support body 7 at 25.6.
It should be added that the support body 7 with its tightening and loosening units 8 has hydraulic lifting devices 26 (Figures 5, 6), so that it can be placed, adjustable in height, on the flange of the RPV head or the lower part of the RPV. Preferably, three such lifting devices are arranged at three points uniformly distributed over the circumference of the support body 7. Each of these lifting devices has a push-off plunger 26.1 with a foot 26.2 and power pistons 26.3 which are mounted on the plunger and are arranged in corresponding hydraulic cylinder bodies 26.4. The feed canals 27 for high-pressure oil are associated with the upward movement of the support body or the downward movement of the power piston 26.3, and the hy-draulic feed canals 28 are associated with the downward movement of the support body or the upward movement of the power pistons 26.3. The associa-ted hydraulic feed lines for the high-pressure oil are not shown, and like-wise not the specific manner of mounting the lifting device 26, which is set into corresponding recesses in the support body and are firmly connec-ted with the latt~r. Through the tandem arrangement of two piston-cylinder units, as shown, a doubling of the effective pushing-off force is achieved, which must supply the weight of the entire screwing and transporting tool of approximately 35 tons plus the weight for the studs with the nuts. ~11 -:
103l9Z08 throe lifting devices 26 must be controlled synchronously in such a manner that uniform lifting or lowaring of the tDol is possible. In particular, fine adjustment by millimeters must also be possible.
The operation of the described screwing and transporting tool turns out as fsllows: It is assumed that the screwing and transporting tool in Figu~e ~ is placed on the flange of the RPV head 2 for opening the RPV head.
Thereupon, tho high-pressure hydraulic system for the three lifting pistons 26 is switched on and the tool is lifted 3 mm by the three lifting pistons.
Next, the gripping nuts 12 located in the tool are screwed on all 52 studs (in Figure 2, the already screwed-on position is shown~, and specifically, on the thread 11, for which purpose the turning drive 14 with its drive pin-ion 14.1 is switched on. The spherical washer 12.4 at the gripping nut serves at the same time for guiding the gripping nuts 12 on the chamfered stud end 11.1, before the threads start to take hold. When the gripping nuts 12 are screwed on, the securing brackets 24 are snapped in place. Now, the tool is lowered again on the head flange 1 by actuating the lifting de-vices 26. Now, the studs must be stretched axially by pressurized oil, which is fed to the tensioning cylinders 13 via the lines 25.4. Then, the power pistons 13.1 are pushed first 3 mm in an idling stroke and then against the spherical washer 12.4, and the studs 6 are now stretched in a defined manner axially by the predetermined amount, which can be read at the dial gago 22.
The gripping nuts therefore serve as the engagement surface for the power pistons.
Now, the nut-turning drives 10 can be switched on, which screw up without effort the respoctive tightening nuts 6.2 via the drive pinions 9 by almost a full turn, until the nuts are arrested by means of the locking device 6.8, 21.3. The hydraulic tensioning device 13, 13.1 is now again controlled so that the pressure drops slowly and the elongation of the studs is taken back. As the next step, pressure ~ust be applied to the lifting cylinder 15, so that the weight of the studs 6 is compensated. When this - 15 _ 2~8 has been accomplished, the drive-screw motors 17 ars switched on and the studs 6 are screwed out step by s~ep (the mo*ors 17 may be of pulse opera_ tion), the support body 7 with the individual tightening and loosening de-vices being made to follow by means of the lifting devices 26. The drive-screw pulsed motors 17 unscrew the studs 6 together with their tightening nuts 6.2 and their gripping nuts 12, the drives 14 and 10 idling along, of course. After checking whether all the studs have been screwed out, the screwing and transporting tool is lifted up, if the finding is positive, by means of a building crane, not shown, and is run to a set-down location.
Thereby, all the studs with their tightening nuts and gripping nuts are thus carried off. Through the holes 2.1 in the RPV head, one can now in-sert plastic plugs for sealing the blind tapped holes 5 in the lower RPV
part, so that subsequently to the lifting of the head, the water-flooding of the reactor room can be started. The head is then taken off completely and refueling can begin which, how0ver, is of no significance for the under-standing of the present invention. It is important, however, that the tool moved to the set-down location contains all studs and tightening nuts so that these can now be subjected to a thorough examination. Further, a close inspection of the blind tapped holes 6.1 can be performed with the RPV
still open, which would not be possible without the removal of the threaded studs.
After the refueling and the inspection have been completed, the reactor pressure vessel is closed in the reverse order; after the head bol-ting has been tightened, the gripping nuts 12 can now be screwed off as the last step and are then carried with this tool to the set-down location.
' .
103~2~B
turning drive 10 with the drive pinion 9 which serves to turn the tightening nut 6.2 via its external gearing 6.5 in the screw-on and screw-off direction.
The nut drive 10 is designed similar to the drive 14. The drive pinion 9, whose gear teeth g.1 mesh with the external gear teeth 6.5 of the tightening nut 6.2, is supported on the shaft 10.1 spring-loaded in the axial direction, so that the engagement of the teeth 9.1 with the teeth 6.5 is facilitated when the tightening and loosening unit 8 is put in place, and jamming is avoided. To this end, there is securely mounted on the shaft 10.1 the washer 10.2, against which the helical compression spring 10.3 is braced and the drive pinion 9 pushes axially against a snap ring 10.~. The electric motor is designated with 10.5 and the transmission unit with 10.6. The transmis_ sion unit 10.6 is attached to the support body 7, for instance, via a U-shaped holder 10.7. 10.8 is a protective sheet-metal cover which is bolted to the support body 7 and covers the drive pinion 9 at the top.
For screwing the threaded studs 6 into and out of the tapped holes 5 of the lower RPV part 1 (see Figure 1), the tightening and loosening units -~
8 are now provided with lifting and support means 15, 16 which can be switch-ed into and out of engagement relative to the studs 6, to provide a support which is rotatable and in the process weight-relieves the screw threads 6.1, -5 of the stud 6 and the pressure vessel 1, respectively, associated with each other at the base end, and the tightening and loosening units 8 further comprise a rotation drive 17 which can be brought into engagement with the studs 6 in a positively force-transmitting manner. The weight of an indivi-dual stud 6 with the tightening nut 6.2 and the gripping nut 12 in the RPV
shown, which is laid out for a power of 1200 MWel, is about 2 tons or mega-ponds (2000 kg). The lifting means 15 are therefore employed for the screw-ing-in or out of the threaded studs 6 to generate a force compensating this weight, so that seizing between the screw threads 6.1, 5 is reliably pre-vented, the support means 16 providing for low friction, preferably rolling friction.
_ g _ . . , ~0:182~8 In detail, the lifting an~ support means 15, 16 are comprised of a lifting cylin~er 15.1, which is arranged concentrically to the screwe~-on gripping nut 12 and in whicll the annular lifting piston 15.2 is disposed, and of a thrust bearing 16, where the lif~ing piston 15.2 with an inner shoulder 15.3 ran be brought into engagement with an outer shoulder 12.6 of the gripping nut 12 via the thrust bearing 16 against the direction of the force of gravity. As will be seen, the lifting cylinder 15.1 is arran-ged axially following the hydraulic tensioning cylinder 13, i.e., is flanged to the upper tensioning cylinder 13, and the lifting piston 15.2 is of double- ~ ~
action design, two hydraulic feed lines being indicated by the dash-dotted ~-lines 15.21, 15.22. The lifting piston 15.2 can therefore be acted upon due `
to its piston shoulder 15.3, which represents the effective hydraulic area, deflected upward via the line 15.21, or downward if acted upon via the line -15.22. rhe upward movement is limited by the stop ring 15.24, which is fas-tened at the upper circumference of the cylinder 15.1 on its inner side rela-tive to the annular support 7. Sealing rings placed in slots are designa-; ted with 15.4 in the arrangement 15. The lower piston shoulder 15.3 can be ~ -brought to a stop with the upper of the power pistons 13.1, as can be seen, and can therefore serve as a restoring pressure piston for the power pistons 13.1 in the direction opposed to its lifting direction. The liting piston 15.2 therefore has a dual function; for one, the weight relief of the parts previously noted, and secondly, the restoring function of these parts.
At the outer circumference of the lifting piston 15.2 there is fastened in an area left free by the lifting cylinder 15.1, the already men-tioned drive motor 14 for the gripping nut 12, whose pinion 14.1 goes through the lifting piston 15.2 in a slot 15.25 to mesh with the gripping nut 12~
Similarly, also the annular support frame 14.7 of the motor 14 is slotted at this point (slot 14.71). To take up the reaction torque of the drive `~
motor 14, the annular frame 14.7, which is welded to the lifting piston 15.2, is guided in the axial direction by the guide bar 18, which is attached at 10382~8 the lifting cylinder 15~1 at 18.1 and 18.2. For this purpose, the annular frame 14.7 has a radially-directed guide bracket 14.8 of U-shaped cross sec-tion (see Figure 3).
The rotation drive 17 is fastened to the support body 7 and is pre-ferably a pneumatically energized drive-screw motor, whose drive pinion 17.1 is in engagement with a coupling member 19 which can be engaged and disen-gaged relative to the stud 6, the teeth 17.2 meshing with the external teeth 19.1 of the coupling member 19. To this end, the drive pinion 17.1 goes through the support body 7 in a slot 7.1 and the sleeve 20 inserted at the inside circumference of the support body 7, in a slot 20.1. The drive pin-ion 17.1 is mounted on the shaft 17.2, secured against rotation, which latter is supported in bearing elements 17.3 which are arranged at an axial distance from each other. ~le housing of the drive 17 is designated with 17.5; it contains the drive-screw motor proper, whose pneumatic feed lines are not visible.
The coupling member 19 is formed by a hollow cylindrical driving disk, for instance, which is supported concentrically and rotatably with respect to the stud 6 and axially spring-loaded in the support body housing, ; i.e., in the sleeve 20, with the external teeth 19.1 and internal teeth 19.2, which can be engaged with corresponding coupling projections and recesses 21.1, 21.2 of a driving ring 21 which is connected with the stud 6, secure against rotation, although displaced longitudinally. ~le axially spring loaded and rotatable support of the driving disk 19 is achieved by the thrust bearing 19.3 which rests via a support ring 19.4 and a helical compression spring 19.5 against a counter-support ring 19.6 with a retaining ring 19.7.
If therefore the tightening and loosening units 8 are put over the respec-tive associated stud 6, then the driving dis~ 19 can give way resiliently in the axial direction until its teeth 19.2 engage with the mating te~th 21.1, 21.2. A retaining ring for the sleeve 20 is designated with 20.2.
The sleeve is furthermore pinned at 20.3 in the support body 7.
1038Z~E~
~le entire screwing and transporting tool, i.e., its respective tightening and loosening units 8, are now arranged for simultaneously screwing-out the studs 6 and the tightening nuts 6.2 sitting on them after the latter have been loosened, and for simultaneously screwing-in the studs 6 and their tightening screws 6.2 before the latter are tightened. For this purpose, the tightening nut 6.2 can be locked to the stud 6 in such a manner that rotation of the tightening nut 6.2 relative to the stud 6 beyond a preselectable screwing-on readiness position or a preselectable readiness-position rotation angle range, is prevented in both directions of rotation.
For this purpose, the driving ring 21 has, at its end facing the tightening nut 6.2, a projection 21.3 with a stop surface pointing in the circumferen-tial direction, and the tightening nut 6.2 is provided at its upper end face with a latch 6.8. This latch 6.8 can be attached at the end face of the tightening nut adjusted in such a manner that the nut 6.2, after traveling through a screw-off rotation angle which is equal to or larger than the angle of rotation required for loosening the nut 6.2 during the axial elon-gation of the stud 6, runs against the stop surface 21.3 with its latch 6.8.
In the case shown in Figure 2, the tightening nut 6.2 is still tight. If it is, therefore, stretched axially by the tensioning cylinder 13 and piston 13.1, and if the tightening nut 6.2 is turned by the drive pinion 9 counter-clockwise, then the tight0ning nut 6.2 can travel through a screwing-off rotation angle which amounts to one full revolution, minus the arc of the projection 21.3 of the driving ring 21. This means, the pitch of the stud and tightening nut thread is chosen accordingly. In the present case, the thread is a metric thread M210 x 8. The pitch of 8 mm per thread is there-fore sufficient for unscrewing the tightening nut 6.2, from which it is con-cluded that the axial elongation of the stud 6 in the permanent condition must be somewhat less than 8 mm. The driving ring 21 is designed as a separate part, which is, for instance, shrunk onto a corresponding shoulder 3~ 6.9 of the stud. This is advantageous because a certain amount of wear 103~Z~I~
takes place at the part 21. i~owever, the invention is not limited to this;
special threaded stu~s can also ~e used whîch have an integrally formed driving ring 21.
The engagement between the latch 6.8 and the stop surface 2l.3 as well as between tlle driving disk l9 and the driving ring 21 is illustra-ted once more in the cross-sectional view according to Figure ~.
As shown particularly in Figure 5> the tool according to the in-vention for the simultaneous tightening or loosening of all the screw con-nections arranged in the pitch circle 22 of the pressure vessel's head bol-ting, is equipped with one tightening and loosening unit 8 for each stud 6 with tightening nut 6.2. The tool is furthermore arranged for transporting to and fro the loosened studs 6 including the tightening nuts 6.2 sitting on them, and for this purpose can be brought into engagement, by means of support surfaces 13.11 of their tightening and loosening units 8, with corresponding counter support surfaces 12.41 of the stud 6. As will be seen, the support and countersupport surfaces 13.11, 12.41 are identical with the contact surfaces with which the power piston 13.1 of the hydraulic tension-ing cylinders 13 and the gripping nut 12 for stretching the stud 6, are in mu*ual engagement.
During the hydraulic elongation of the stud 6, the elongation can be read at a dial gage 22, whose plunger 22.1 rests against the reference surface 23.1 of a measuring pin 23. This measuring pin 23, with which every stud 6 is providedJ extends through a hole 23.2 into the interior of the stud 6 and therefore does not participate in the elongation of the stud 6.
The mounting nuts for holding the dial gage 22 are designated with 22.2 and 22.3.
The bracket 24 serves, as known per se, for the purpose of securing ; against rotation. With its two angled-off ends, which make contact with the end face of the gripping nut 12, it is secured by the pin 24.1 and the threaded bolt 24.2. It prevents the gripping nut 12 from being turned off .... . . .
:
~03~2(~1~
during the movement of the stud 6.
Witll 25 is designated as a whole a high-pressure hydraulic feeding arrangement. A hydraulic ring line, not visible, leads to the individual shut-off device 25.1 and from there via the line 25.2 and the distributor head 25.3 as well as the lines 25.4 to the two tensioning cylinders 13, which are provided with corresponding hydraulic canals 13.3. Corresponding sealing rings between the piston 13.1 and the cylinders 13 are designated as a whole with 13.4. Oil-leak monitoring canals carry the reference symbol 13.5. The escape of leakage oil can be recognized at transparent, screwed-in caps 13.51.
The mounting frame 25.5 for the hydraulic device 25 is bolted to the support body 7 at 25.6.
It should be added that the support body 7 with its tightening and loosening units 8 has hydraulic lifting devices 26 (Figures 5, 6), so that it can be placed, adjustable in height, on the flange of the RPV head or the lower part of the RPV. Preferably, three such lifting devices are arranged at three points uniformly distributed over the circumference of the support body 7. Each of these lifting devices has a push-off plunger 26.1 with a foot 26.2 and power pistons 26.3 which are mounted on the plunger and are arranged in corresponding hydraulic cylinder bodies 26.4. The feed canals 27 for high-pressure oil are associated with the upward movement of the support body or the downward movement of the power piston 26.3, and the hy-draulic feed canals 28 are associated with the downward movement of the support body or the upward movement of the power pistons 26.3. The associa-ted hydraulic feed lines for the high-pressure oil are not shown, and like-wise not the specific manner of mounting the lifting device 26, which is set into corresponding recesses in the support body and are firmly connec-ted with the latt~r. Through the tandem arrangement of two piston-cylinder units, as shown, a doubling of the effective pushing-off force is achieved, which must supply the weight of the entire screwing and transporting tool of approximately 35 tons plus the weight for the studs with the nuts. ~11 -:
103l9Z08 throe lifting devices 26 must be controlled synchronously in such a manner that uniform lifting or lowaring of the tDol is possible. In particular, fine adjustment by millimeters must also be possible.
The operation of the described screwing and transporting tool turns out as fsllows: It is assumed that the screwing and transporting tool in Figu~e ~ is placed on the flange of the RPV head 2 for opening the RPV head.
Thereupon, tho high-pressure hydraulic system for the three lifting pistons 26 is switched on and the tool is lifted 3 mm by the three lifting pistons.
Next, the gripping nuts 12 located in the tool are screwed on all 52 studs (in Figure 2, the already screwed-on position is shown~, and specifically, on the thread 11, for which purpose the turning drive 14 with its drive pin-ion 14.1 is switched on. The spherical washer 12.4 at the gripping nut serves at the same time for guiding the gripping nuts 12 on the chamfered stud end 11.1, before the threads start to take hold. When the gripping nuts 12 are screwed on, the securing brackets 24 are snapped in place. Now, the tool is lowered again on the head flange 1 by actuating the lifting de-vices 26. Now, the studs must be stretched axially by pressurized oil, which is fed to the tensioning cylinders 13 via the lines 25.4. Then, the power pistons 13.1 are pushed first 3 mm in an idling stroke and then against the spherical washer 12.4, and the studs 6 are now stretched in a defined manner axially by the predetermined amount, which can be read at the dial gago 22.
The gripping nuts therefore serve as the engagement surface for the power pistons.
Now, the nut-turning drives 10 can be switched on, which screw up without effort the respoctive tightening nuts 6.2 via the drive pinions 9 by almost a full turn, until the nuts are arrested by means of the locking device 6.8, 21.3. The hydraulic tensioning device 13, 13.1 is now again controlled so that the pressure drops slowly and the elongation of the studs is taken back. As the next step, pressure ~ust be applied to the lifting cylinder 15, so that the weight of the studs 6 is compensated. When this - 15 _ 2~8 has been accomplished, the drive-screw motors 17 ars switched on and the studs 6 are screwed out step by s~ep (the mo*ors 17 may be of pulse opera_ tion), the support body 7 with the individual tightening and loosening de-vices being made to follow by means of the lifting devices 26. The drive-screw pulsed motors 17 unscrew the studs 6 together with their tightening nuts 6.2 and their gripping nuts 12, the drives 14 and 10 idling along, of course. After checking whether all the studs have been screwed out, the screwing and transporting tool is lifted up, if the finding is positive, by means of a building crane, not shown, and is run to a set-down location.
Thereby, all the studs with their tightening nuts and gripping nuts are thus carried off. Through the holes 2.1 in the RPV head, one can now in-sert plastic plugs for sealing the blind tapped holes 5 in the lower RPV
part, so that subsequently to the lifting of the head, the water-flooding of the reactor room can be started. The head is then taken off completely and refueling can begin which, how0ver, is of no significance for the under-standing of the present invention. It is important, however, that the tool moved to the set-down location contains all studs and tightening nuts so that these can now be subjected to a thorough examination. Further, a close inspection of the blind tapped holes 6.1 can be performed with the RPV
still open, which would not be possible without the removal of the threaded studs.
After the refueling and the inspection have been completed, the reactor pressure vessel is closed in the reverse order; after the head bol-ting has been tightened, the gripping nuts 12 can now be screwed off as the last step and are then carried with this tool to the set-down location.
' .
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for unscrewing and screwing nuclear reactor pressure vessel head-retaining nuts and screw studs, the studs extending upwardly through stud holes in a head flange of a removable head of a reactor pres-sure vessel, the studs having threaded lower ends screwed into threaded holes in the pressure vessel's top and threaded portions on which the nuts are screwed above the head flange to hold down the head on the pressure vessel with the studs under pretension between the vessel's top and the nuts, the nuts having external gear teeth for their rotation and the studs having upper ends spaced above the nuts; said device comprising a support body and means for supporting said body at controllable heights on said head flange; and unscrewing and screwing units for said nuts and studs, mounted on said body and having axial passages for releasable insertion of the studs and nuts; each of said units for a stud and nut when inserted in the unit's passage, having a pinion releasably meshing with the nut's said gear teeth and means for reversingly driving said pinion for unscrewing and screwing movements of the nut on the stud, gripping means for releasa-bly gripping the upper end of the stud above the nut, and means for apply-ing upward force to said gripping means for stretching the stud upwardly from the pressure vessel's top to free the nut from said pretension during said movements; each of said units further having means for releasably engaging and reversibly rotating the stud so its said lower end can be unscrewed and screwed in the threaded hole in the pressure vessel's top while the nut remains screwed on the stud, and means for applying a lifting force to both the nut and stud to relieve the stud's said lower end from the weight of the nut and stud while being unscrewed and screwed in the pressure ves-sel's threaded hole.
2. The device of claim 1 in which each of said units has means for locking the nut against rotation relative to the stud's threaded lower end while this lower end is unscrewed from the threaded hole in the pressure vessel's top or screwed into said hole, after a limited rotation of the nut on said lower end, said limited rotation being insufficient to unscrew the nut completely from said lower end but sufficient to leave the unit in a free position when the unit is unscrewed driving stretching and the stretching is released, or to position the nut for said pretension without said stretching after release of said stretching.
3. The device of claim 1 in which said gripping means is for holding the stud's said upper end with the balance of the stud and the nut suspen-ded therefrom in the unit's said axial passage, so that transport of the unit transports the stud and nut.
4. The device of claim 3 in which said support body has one of said units for each one of said head-retaining nuts and studs, the support body being removable from the pressure vessel's head so that after unscrewing of the studs' said lower ends, said tool can transport all of the studs with the nuts screwed thereon, from and to the pressure vessel's head.
5. The device of claim 3 in which said gripping means is formed by each of said upper ends of the studs being externally screw-threaded, and each unit having a rotative gripping nut and means for rotating this nut to screw it on the stud's upper end, the nut having an annular bottom thrust surface, said means for applying said upward force being formed by at least one annular piston and a cylinder therefor coaxially arranged as a part of the unit's said axial passage and through which said stud can be inserted, the annular piston having an upper end provided with a thrust bearing con-necting with said gripping nut's said bottom surface and applying thereto said upward force.
6. The device of claim 5 in which said means for applying said lifting force comprises an annular lifting piston surrounding said gripping nut and having an internal flange engaging the nut's said annular bottom surface, and means for supplying said annular piston with fluid for forcing it both up and down.
7. A device for securing or releasing a connector capable of connec-ting a first member to a second member, the connector comprising a stud having a threaded end region and a threaded intermediate region, and an ad-justing nut on the threaded intermediate region, the arrangement being such that, during connection, the stud extends through an aperture in the second member and is located at its threaded end region in a threaded hole in the first member, with the adjusting nut on that side of the second member remote from the first member and urging the second member towards the first member; the device comprising: a support which is intended to be adjustable parallel to the axis of the stud, and, carried by the support:
(1) means for gripping an end region of the stud remote from the said threaded end region;
(2) means for axially extending the stud;
(3) first drive means for rotating the adjusting nut relative to the stud;
(4) second drive means for screwing and unscrewing the stud (and the adjusting nut carried thereon) relative to the first member; and (5) lifting means for taking up the weight of the stud and ad-justing nut whilst they are being acted upon by the second drive means.
(1) means for gripping an end region of the stud remote from the said threaded end region;
(2) means for axially extending the stud;
(3) first drive means for rotating the adjusting nut relative to the stud;
(4) second drive means for screwing and unscrewing the stud (and the adjusting nut carried thereon) relative to the first member; and (5) lifting means for taking up the weight of the stud and ad-justing nut whilst they are being acted upon by the second drive means.
8. A device according to claim 7, wherein the means for gripping the remote end region of the stud is constituted by a gripping nut and drive for screwing and unscrewing the gripping nut on a threaded portion of said remote end region.
9. A device according to claim 8, wherein the lifting means is con-stituted by a cylinder disposed concentrically with the gripping nut and a piston disposed within the cylinder for bearing against the gripping nut when acted upon by a pressure medium.
10. A device according to claim 9, wherein the drive for screwing and unscrewing the gripping nut is constituted by a motor coupled to a pinion which is engageable with the gripping nut through openings in the lifting cylinder and piston.
11. A device according to claim 8 or 9, wherein the piston is adap-ted to bear against a peripheral flange on the gripping nut by way of a thrust bearing.
12. A device according to claim 9, wherein the means for axially ex-tending the stud is constituted by a clamping cylinder fixed to the support and a piston within said cylinder for bearing against a shoulder to be fixed to or provided on the stud, when acted upon by a pressure medium.
13. A device according to claim 12, wherein the piston in the clamping cylinder is intended to be acted upon by the pressure medium on one side only, whilst the piston of the lifting means is intended to be acted upon by its pressure medium on both sides, and the two pistons are linked together in such a way that the lifting piston may act as a drawback ram for the clamping piston in the directing in which pressure medium is not intended to act on the clamping piston.
14. A device according to claim 7, 8 or 9, wherein the first drive means is constituted by a drive motor coupled to a pinion which is engageable with teeth on the periphery of the adjusting nut.
15. A device according to claim 7, wherein the second drive means is constituted by a drive motor coupled to a pinion which engages with a coupl-ing member capable of coupling the pinion to the stud.
16. A device according to claim 15, wherein the drive motor of the said second drive means is a drive screw motor.
17. A device according to claim 15, wherein the coupling member is constituted by an annular ring mounted rotatably and axially resiliently within a housing intended to encircle the stud, the ring being provided with external teeth with which the pinion engages and at least one internal tooth capable of engaging with at least one corresponding projection or recess on a catch ring to be secured against rotation on the stud.
18. A device according to claim 12, further including a bearing sur-face fixed to the support for engaging with a corresponding counter-bearing surface to be fixed to or provided on the stud in order to transport the stud and associated adjusting nut to and from the site of the connection be-tween the first and second members.
19. A device according to claim 18, wherein the counterbearing sur-face is constituted by a portion of the gripping nut which also defines the shoulder, and the bearing surface is the same as that surface of the clam-ping piston by means of which it bears against the said shoulder.
20. A device according to claim 7, 8 or 9, the device being adapted to secure or release a plurality of connectors simultaneously.
21. The combination according to claim 17, wherein the catch ring is provided with 8 projection and the adjusting nut is provided with a rat-chet, whereby, after a predetermined angle of rotation of the adjusting nut relative to the stud, the ratchet bears against the projection.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2459645A DE2459645C2 (en) | 1974-12-17 | 1974-12-17 | Screwing and transport device for a screwed cover of a pressure vessel, in particular a nuclear reactor pressure vessel, consisting of studs and associated fastening nuts |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1038208A true CA1038208A (en) | 1978-09-12 |
Family
ID=5933638
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA241,827A Expired CA1038208A (en) | 1974-12-17 | 1975-12-16 | Motor-driven screwing and transporting tool for reactor pressure vessel head retaining fastenings |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5850830B2 (en) |
| BE (1) | BE836577A (en) |
| BR (1) | BR7507721A (en) |
| CA (1) | CA1038208A (en) |
| CH (1) | CH613144A5 (en) |
| DE (1) | DE2459645C2 (en) |
| ES (1) | ES443573A1 (en) |
| FR (1) | FR2294795A1 (en) |
| GB (1) | GB1506654A (en) |
| IT (1) | IT1050793B (en) |
| NL (1) | NL179635C (en) |
| SE (1) | SE416714B (en) |
| SU (1) | SU839437A3 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111554415A (en) * | 2020-05-15 | 2020-08-18 | 中国核动力研究设计院 | Guide positioning structure for assembling top cover and container of reactor pressure vessel |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2364529A1 (en) * | 1976-09-11 | 1978-04-07 | Kloeckner Werke Ag | TIGHTENING AND UNSCREWING DEVICE FOR OPENING AND CLOSING THE LID OF A NUCLEAR REACTOR TANK |
| FR2367574A1 (en) * | 1976-10-15 | 1978-05-12 | France Etat | Automatic insertion and removal of heavy gudgeon bolts - by machine with fully synchronised tightening and slackening procedure |
| DE2749536C3 (en) * | 1977-11-03 | 1980-09-04 | Kraftwerk Union Ag, 4330 Muelheim | Arrangement for measuring the preload of a screw bolt used in particular to close a reactor pressure vessel |
| DE2814072A1 (en) * | 1978-03-30 | 1979-10-11 | Kraftwerk Union Ag | Bolt tensioner for clamping pressure vessel cover - has nut running unit and hydraulically actuated piston which seats around bolts |
| JPS5659698U (en) * | 1979-10-16 | 1981-05-21 | ||
| US4523742A (en) * | 1982-01-25 | 1985-06-18 | Gripper, Inc. | Apparatus for tensioning a stud and method of doing same |
| GB2124119A (en) * | 1982-06-26 | 1984-02-15 | Hydra Tight Ltd | A hydraulic bolt tensioning tool with power drive for rotating a nut |
| JPS59155315U (en) * | 1983-04-05 | 1984-10-18 | 三菱重工業株式会社 | Bolt tightening device |
| JPS59171038U (en) * | 1983-04-28 | 1984-11-15 | 石川島播磨重工業株式会社 | Nut attachment/detachment device |
| FR2564767B1 (en) * | 1984-05-24 | 1986-10-10 | Kley France | MACHINE FOR SCREWING AND UNSCREWING A STRETCHED STUD |
| FR2631868B1 (en) * | 1988-05-25 | 1990-09-21 | Framatome Sa | DEVICE AND METHOD FOR SCREWING AND SCREWING A NUT ONTO A CONNECTING ELEMENT |
| JPH02286326A (en) * | 1989-04-28 | 1990-11-26 | Takenaka Komuten Co Ltd | Structure of coating on concrete body |
| CN111531355A (en) * | 2020-05-09 | 2020-08-14 | 上海硕大电子科技有限公司 | Device and method for installing sealing ring |
| CN111958539A (en) * | 2020-08-10 | 2020-11-20 | 彭珍 | Automatic installation equipment that adds of bearing O type circle |
| CN112025280A (en) * | 2020-08-18 | 2020-12-04 | 湖州爆米花信息科技有限公司 | Bolt assembling machine for steam fittings |
| CN111998178A (en) * | 2020-08-29 | 2020-11-27 | 中电诚达医药工程设计(河北)有限公司 | Convenient equipment maintenance entry structure |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2258859A1 (en) * | 1972-12-01 | 1974-06-12 | Masch Und Bohrgeraete Fabrik | HYDRAULIC CLAMPING DEVICE |
| DE7247233U (en) * | 1972-12-23 | 1974-06-06 | Kloeckner Werke Ag | Screw tensioning device |
-
1974
- 1974-12-17 DE DE2459645A patent/DE2459645C2/en not_active Expired
-
1975
- 1975-10-09 NL NLAANVRAGE7511883,A patent/NL179635C/en not_active IP Right Cessation
- 1975-11-19 FR FR7535344A patent/FR2294795A1/en active Granted
- 1975-11-21 BR BR7507721*A patent/BR7507721A/en unknown
- 1975-12-04 CH CH1577575A patent/CH613144A5/en not_active IP Right Cessation
- 1975-12-08 SU SU752196108A patent/SU839437A3/en active
- 1975-12-09 GB GB50513/75A patent/GB1506654A/en not_active Expired
- 1975-12-12 BE BE162693A patent/BE836577A/en not_active IP Right Cessation
- 1975-12-15 JP JP50149417A patent/JPS5850830B2/en not_active Expired
- 1975-12-16 IT IT30316/75A patent/IT1050793B/en active
- 1975-12-16 CA CA241,827A patent/CA1038208A/en not_active Expired
- 1975-12-16 SE SE7514198A patent/SE416714B/en not_active IP Right Cessation
- 1975-12-17 ES ES443573A patent/ES443573A1/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111554415A (en) * | 2020-05-15 | 2020-08-18 | 中国核动力研究设计院 | Guide positioning structure for assembling top cover and container of reactor pressure vessel |
| CN111554415B (en) * | 2020-05-15 | 2022-02-11 | 中国核动力研究设计院 | Guide positioning structure for assembling top cover and container of reactor pressure vessel |
Also Published As
| Publication number | Publication date |
|---|---|
| NL7511883A (en) | 1976-06-21 |
| FR2294795A1 (en) | 1976-07-16 |
| SE416714B (en) | 1981-02-02 |
| DE2459645A1 (en) | 1976-07-01 |
| DE2459645C2 (en) | 1983-12-08 |
| IT1050793B (en) | 1981-03-20 |
| SE7514198L (en) | 1976-06-18 |
| GB1506654A (en) | 1978-04-05 |
| ES443573A1 (en) | 1977-08-16 |
| NL179635C (en) | 1986-10-16 |
| CH613144A5 (en) | 1979-09-14 |
| JPS5850830B2 (en) | 1983-11-12 |
| BR7507721A (en) | 1976-09-08 |
| FR2294795B1 (en) | 1980-09-19 |
| JPS5186820A (en) | 1976-07-29 |
| BE836577A (en) | 1976-04-01 |
| SU839437A3 (en) | 1981-06-15 |
| NL179635B (en) | 1986-05-16 |
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