GB2046155A - Method and Apparatus for Tightening Nuts - Google Patents

Abstract

To tighten two nuts mounted to combine linearly two bars having male screw threads, an apparatus has a first spanner (6) for the upper nut, a second spanner (9) for the lower nut and a driving apparatus for rotating the second spanner. The driving apparatus comprises a ratchet (11) engaging teeth (12) formed on the second spanner and a linearly driving apparatus e.g. fluid motor, or electrical means (14) for pushing the ratchet via a linear slide. The first spanner and the second spanner are combined by a joint apparatus (63) in order to permit easy separation or combination. The orientation of the first spanner is adjustable by manual worm and gear to accommodate random orientations of the two nuts. <IMAGE>

Description

SPECIFICATION Method and Apparatus for Tightening Nuts This invention relates to a method and an apparatus for tightening two nuts.

As a linear combination method of two bars, such a mechanical method is well known wherein on the surfaces of bars male screws are formed, and at least two nuts adapted for the male screws combine two bars linearly. One of them is a coupling nut. Others are lock nuts.

However, in the mechanical combination some amount of backlash remains between the male screw of bars and the female screw of nuts.

Residual backlash causes an easy loosening of the coupling or a bending at the coupling of the bars.

If two reinforcing iron bars are combined by this method and buried in concrete cement, frequent actions of external forces upon the buildings bend the reinforcing iron bars at the coupling and cracks occur on concrete surfaces above the loosened couplings.

Experimental results teach the inventor the minimum torque for tightening nuts applied to the bars of 33 mm diameter is 200 kg-m. Therefore a conventional manual handling of spanners is insufficient to extinguish the backlash perfectly.

Instead of the conventional manual tightening the inventor has made some inventions of automatic tightening apparatus. Hydraulic wrenches contrived by the inventor are shown in Japanese patent official gazette for publicity No: 24277/77 Japanese patent official gazette for laying open No: 36800/78.

All of the tightening apparatuses have two spanners arranged along a vertical line, a rack device to rotate one spanner whose outer surface has cogs and a hydraulic cylinder for driving the rack back and forth.

However, apparatuses, of this rack type have some inconveniences. Because a single motion of the rack nameiy the hydraulic cylinder rotates the spanner to tighten the nuts, the length of the rack and the stroke of the hydraulic cylinder must be very long. The apparatus of the rack type is excessively large and heavy. It is too difficult for one operator to lift up and handle it.

There remains another inconvenience in the previously described apparatuses. If there are bars or other building materials in the neighbourhood of the apparatus, the tightening operation will be disturbed if, during operation, the apparatus comes into contact with the obstacles and the rotation of the apparatus is prevented.

The two spanners of the apparatus operate to tighten two nuts at the same time. The relationship of the two spanners to the main body of the apparatus is not symmetrical, because only one spanner is driven to rotate with regard to the main body whilst the other spanner is fixed to the main body. If the friction torques of two nuts are equal, half amount of the relative rotation between two spanners is allotted to the fixed spanner and the main body--inctuding the rack and the hydraulic cylinder-rotates the half amount of the rotation angle with respect to the ground.

In other words if the apparatus is prevented from rotating, it can no longer be used to tighten two nuts. Therefore this prior art apparatus is not useful where obstacles are close to the bar to be coupled.

The inventor finds this inconvenience of the rack type apparatus derives from the fact that the rack and the cogs formed on the spanner cannot be disengaged from each other, that is the spanner and the driving device are rigorously connected. Therefore, if the engagement between the spanner and the driving device can be broken off, this inconvenience shall vanish.

A principal object of this invention is to provide a method and an apparatus for tightening wherein two nuts combining two bars shall be tightened so powerfully that any backlash does not occur between the male screw of the bars and the female screw of nuts in spite of external forces- either pulling or pressing force acting on the combined bars, and, in a preferred form, so that the tightening operation is not disturbed by the obstacles close to the apparatus.

According to the present invention in a first aspect there is provided a method for tightening two nuts in a combination of two bars which have a whole surface or a partial surface with male screws by a tightening apparatus, hanging a first spanner member upon a nut, driving a linearly driving apparatus to turn said second spanner member relative to a main body by a ratchet device, returning said linearly driving apparatus to an original state, and repeating said driving and said returning operations to tighten the nuts.

According to the present invention in a second aspect there is provided tightening apparatus comprising: a first main body, a second main body fixed to the first main body to prevent any relative rotation between the bodies, a first spanner member located in the first main body; a second spanner member rotatably mounted in the second main body about a first axis and having a spanner portion in its inner surface and ratchet cogs in its outer surface; a carrier slidably mounted in the second main body, a ratchet claw pivoted on the carrier and adapted to engage with said ratchet cogs, resilient means connecting said ratchet claw and said carrier to urge said ratchet claw toward said ratchet cogs, and a linearly driving apparatus operative to drive said carrier in a direction such that the ratchet claw rotates said second spanner member.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings. In the drawings: Figure 1 is a plan view of a tightening apparatus which constitutes a preferred embodiment of this invention; Figure 2 is a front view of the tightening apparatus; Figure 3 is a sectional plan view taken along line Ill-Ill in Figure 2.

Figure 4 is a right side view of the apparatus; Figure 5 is a partially section front view of the carrier portion taken on line V-V in Figure 1; Figure 6 is a sectional view taken on line VI VI in Figure 2; Figure 7 is a perspective view of the individual component units of the tightening apparatus; Figure 8 is a simplified side view of an iron bar fitted with a lock nut; Figure 9 is a simplified side view of the iron bar fitted with a lock nut and a coupling nut, and an iron bar to be coupled; Figure 10 is a simplified side view of two iron bars coupled and locked by three nuts; and Figure 11 is a simplified side view of two iron bars, three nuts and the tightening apparatus in its operative location.

A tightening apparatus 1 comprises a main body 2, a first spanner member 6, a second spanner member 9 and a linearly driving apparatus 14. The main body 2 consists of a first main body 3, and a second main body 4. The second main body 4 can be separated from the first main body 3 along an axial direction. But if they are connected to each other, no relative rotation around an axial line is permitted.

The first spanner member 6 is rotatably mounted in the first main body 3. A rotation adjustment device 7 can change the relative rotation of the first spanner member 6 with regard to the first main body 3.

The second spanner member 9 is also rotatively mounted in the second main body 4, whose rotation axis is common with the first spanner member 6.

The second main body 4 includes a carrier 10 which can slide along a horizontal line, a ratchet claw 11 pivotally mounted on the carrier 10, a resilient member 13 affixed between the carrier 10 and a ratchet claw 11 to push the ratchet claw 11 upon ratchet cogs 12, and a disengagement device 1 5 which can slip out the ratchet claw 11 from the cogs 12.

The first main body 3 has a housing which consists of an upper plate 16, a lower plate 17, two side plates 1 8, 1 9 and a rear plate 20. U-form notches are formed at the front of the upper plate 16 and the lower plate 1 7. In the housing a worm 24 is rotatively mounted by a bearing 22 and a bearing 23 which are fixed upon the side plates 18 and 19 by bolts 21. At an external end of the worm shaft a knob 25 is affixed.

In an open front of the housing the U-form first spanner member 6 is mounted. On the outer surface of the first spanner member 6 a worm gear 26 which engages the worm 24 is formed.

On the top and on the bottom of the first spanner member 6 guide arcs 27, 27 are cut out. The guide arcs 27, 27 are held in arch plates 29, 29 fixed on the inner surfaces of the plate 1 6 and 1 7 of the housing by bolts 28. Therefore the first spanner member 6 can rotate in the arch plates 29, 29 around an imaginary centre axis of the arch plate 29, 29.

If the operator turns the knob 25, the worm 24 rotates the first spanner member 6 finely.

Thus, the worm 24, worm gear 26 of the first spanner member 6 and the knob 25 compose the rotation adjustment device 7.

A spanner portion 5 of the first spanner member 6 is shown in Figure 2, Figure 6, Figure 7 and Figure 11. Namely at the upper half of the spanner portion 5 a narrow U-form notch is cut out to fit with bars, and the lower half of the spanner portion 5 has a polygonal surface 31 adaptable for nuts (in the embodiment the nuts are assumed to be hexagonal). On the opening front of the polygonal surface 31 two bent plates 32, 32 are fixed by bolts 33.

Of course the diameter of the U-form notch 34 and 35 of the upper plate 1 6 and the lower plate 1 7 of the housing is determined not to interfere with the bars to be combined.

The first main body 3 has a fitting device 37 fixed on the bottom surface of the lower plate 1 7.

The fitting device 37 has two fitting members 36, 36 on both sides of the bottom.

On the other hand the second main body 4 has a housing including a front plate 40, a side plate 41, a rear plate 42 and another rear plate 43. The housing is open in front (Figure 3).

In the housing a carrier 10 is arranged in a longitudinal direction. The carrier 10 is composed of an upper board 44, a lower board 45, and two side boards 46, 47. The carrier 10 can slide along the longitudinal passage determined by three guide pins 48, 48, 48 and the two plates 38, 39 of the housing.

Within the carrier 10, a ratchet claw 11 is connected with both plates 44 and 45 by a pivot 49. A resilient member 13 is pinned at the both ends by a pin 50 of the carrier 10 and by a pin 51 fixed on the ratchet claw 11. The resilient member 13 pulls the ratchet claw 11 to turn counterclockwise in Figure 3.

In a hole of the side board 47 a stopper bolt 52 is screwed in, which confines the ratchet claw 11 to turn clockwise for the convenience of assembling this apparatus.

On the upper plate 38 a slit 53 is perforated in a longitudinal direction. At the top of the carrier 10 a knob bolt 54 for fine adjustment is affixed, whose head projects upward through the slit 53.

In the second main body 4 a return spring 55 is arranged to return the carrier 10 to the original position. The return spring 55 is sandwiched between a spring holder 56 of the carrier 10 and a spring box 57 of the side plate 41 of the housing.

In the opening front of the second main body 4 a second spanner member 9 having a spanner portion 8 is rotatatively arranged. Ratchet cogs 12 are cut out on the outer surface of the second spanner member 9 in order to engage with the ratchet claw 11. The second spanner member 9 also has two guide arcs 58, 58 at the top and at the bottom. Then two arch plates 60, 60 are fixed on the upper plate 38 and on the lower plate 39 of the housing by several bolts 59. Like the first spanner member 6, the second spanner member 9 can rotate around an imaginary centre axis of the arch plate 60, 60. The rotation axes of the two spanner members 6, 9 are identical.

At the front portion of the upper plate'38 and the lower plate 39 U-form notches are formed.

The diameter of the notches is bigger than that of U-form notch 3Q of the first spanner portion 5, because the second spanner member 9 must slip out of the nut vertically.

Upon the top of the upper plate 38 behind the second spanner member 9 a main column 61 is mounted. Two pin holes 62, 62 are punched on the front and on the rear portion of the main column 61 near the top.

The first main body 3 and the second main body 4 are combined by a joint apparatus 63.

Namely the joint apparatus 63 consists of a shaft portion 65 for inserting into the main column 61 and a top plank 66 fixed on the shaft portion 65 (Figure 7). Through the shaft portion 65 pin holes 64 are bored, which shall communicate with the pin holes 62 of the main column 61 when they are assembled.

The top plank 66 can be inserted between two fitting members 36 of the fitting device 37 beneath the first main body 3 by sliding forwardly.

The joint 63 is combined with the second main body 4 by inserting the shaft portion 65 into the main column 61 and pushing a fastening pin 67 into the pin holes 62, 64, 64 and 62 forwardly.

The fastening pin 67 prevents the joint apparatus 63 of slipping out and of rotating in the main column 61.

At the side end of the second main body 4, a receptacle casing 70 is fixed. As demonstrated well in Figure 3, Figure 4 and Figure 7, the receptacle casing 70 includes an opening punched crosswise and an inner cavity 69.

As linearly driving apparatus 14, a hydraulic cylinder 71 of mono-drive type with return spring is used in this embodiment. In the hydraulic cylinder of mono-drive type with return spring, a piston rod 72 is pushed forward by the compressed oil injected from an external pump (not shown) through a coupler 73. The piston rod 72 returns to the original position by a return spring (not shown) furnished in the casing. Such type of hydraulic cylinder need only a single coupler and a hose (not shown).

The hydraulic cylinder 71 has an inserting portion 76 at front end. The inserting portion 76 consists of cross-shaped protuberances 74 and a neck 75.

The hydraulic cylinder 71 is coupled with the second main body 4 by inserting the inserting portion 76 into the cavity 69 through the opening 68 and by turning the hydraulic cylinder 71 in an angle of 45 degrees. Especially as shown in Figure 3 if a locking device is equipped in the receptacle casing 70, it will assure the coupling of the hydraulic cylinder 71.

As linear driving apparatus 14 instead of the mono-drive type another hydraulic cylinder of double-drive type is also available. Though not illustrated, a linear driving apparatus can be composed of an electric motor or a fluid motor, and a reduction gear device driven by the motor.

A vertical holder 78 is erected on the receptacle casing 70 of the second main body 4.

And a side holder 79 projects from the side of the main column 61.

A disengagement device 1 5 which can release the engagement between the ratchet claw 11 and the ratchet cogs 1 2 is mounted close to the ratchet claw 11 in the second main body 4. The disengagement device 1 5 comprises a pin 80 which is rotatably supported by the upper plate 38 and the lower plate 39 and projected above the upper plate, an arm affixed on the middle of the pin 80 and a lever 82 attached on the top of the pin 80. If the operator turns the lever 82 clockwise (Figure 3) the ratchet claw 11 slips out of the cog 12.

Of course other disengagement devices may also be available. A disengagement device is primarily only necessary if obstacles e.g., other bars or building materials, stand in the neighbourhood of the bar to be coupled. Thus, if obstacles are not present, the disegagement device can be omitted.

A preferred method for combining two bars is demonstrated in Figures 8 to 11. At least two nuts are necessary to combine the two bars A and B shown in the Figures. In this embodiment three nuts C, D and E are used.

Male screws A' and B' are formed on end portion or the whole of the surfaces of the bars A and B. Female screws C', D', and E' are tapped in the nuts C, D, and E.

At first the lock nut C is screwed on the standing bar A, where the length of the male screw projected upward is equal to half of the coupling nut D (Figure 8).

Seconds on the projected male screw A' the long coupling nut D is screwed on to the depth to touch on the former lock nut C (Figure 9).

Thirdly the other bar B on which the lock nut E was preliminary affixed is screwed into the coupling nut D to the depth to contact with the standing bar A (Figure 10).

The two lock nuts C and E should be turned as far as possible by hand. Then, the tightening apparatus is used to fasten two lock nuts C and E.

At first the joint apparatus 63 is connected with the second main body 4 by inserting the fastening pin 67 through the pin holes 62 and 64, but the first main body 3 is separated from the joint apparatus 63.

The operator lifts up the first main body 3 above the top of the upper bar B, puts the first spanner member 6 around the bar B, descends the first main body 3 and hangs it upon the upper nut E. This state is stable by itself because the Uform notch 30 is narrower than the nut E. Then turning the knob 25, the operator adjusts the arrangement of the first main body 3 to coincide with the arrangement of the lower nut C. Then the operator lifts up the second main body 4 holding the vertical holder 78 and the side holder 79 and inserts the top plank 66 of the joint apparatus 63 into the fitting device 37 of the first main body 3 to adapt the second spanner member 9 to the lower nut C (Figure 11).

Such a coupling operation of the first main body 3 and the joint apparatus 63 is necessary if the hexagonal surfaces of both nuts E and C are not parallel.

If the hexagonal surfaces of the nuts E, C are parallel, the operator can fit the fully assembled apparatus including both main bodies 3 and 4 upon two nuts E and C at the same time.

It is very convenient to coincide the disposition of both nuts C and E in the rough fastening done by hand.

After these preliminary manipulations, the operator switches on the fluid pressure pump to supply compressed fluid into the hydraulic cylinder 71. The piston rod 72 is sent forward by the compressed fluid-air, oil or water-and pushes the carrier 10. The ratchet claw 11 pushes a ratchet cog 12. The second spanner member 9 turns the nut C in a unit angle corresponding to the centre angle of the ratchet cogs 12.

Because the first main body 3 and the second main body 4 are coupled to prevent a relative rotation as mentioned before, the unit rotation is allotted to be shared between nuts E and C. If the frictions of the nuts E and C are the same, the nuts E and C are rotated by half a unit angle in opposite directions and the second main body 4 is turned clockwise by half a unit angle.

If one operation of tightening is not enough, the operator repeats the same operation. The operator exhausts the fluid from the hydraulic cylinder 71. The ratchet claw 11 on the carrier 10 goes backward and becomes engaged to a second cog 12 of the second spanner member 9.

The operator switch again on the fluid pump to supply into the cylinder 71. The piston rod 72 pushes the carrier forward. The ratchet claw 11 sends the second cog 12. The second spanner member 9 turns in another unit angle. As mentioned before the unit turn is allotted between the nuts C and E.

After several repetitions two nuts C and E are tightened enough. Maximum count of repetitions is equal to the number of cogs 12. In this embodiment it is four.

To remove the tightening apparatus 1 from the nuts C and E, the operator extracts the fastening pin 67 to separate the second main body 4 from the first main body 3. Then the operator puts the second main body 4 on the ground and turns the lever 82 to disengage the ratchet claw and cogs.

Holding the disengagement state, he rotates the second main body 4 till the spanner member 9 returns to the original arrangement. Under this coincident situation the second main body 4 can be slipped out of the nut C.

With respect to the first main body 3, the operator lifts it up above the top of the upper bar B and takes it off from the bars.

The above mentioned method is available if there is no obstacles close to the bars to be combined.

If other bars stand near the bars as shown in Figure 1 by imaginary lines, it is necessary to disengage the ratchet device 11, 12 and to return the apparatus 1 to the original arrangement by rotating the knob 25 when the apparatus 1 collides with another bar.

As previously described, when the second spanner member 9 is turned through a unit angle with respect to the tightening apparatus, the tightening apparatus 1 rotates to a reverse direction through about half of the unit angle by the reaction. After one or several repetitions of the tightening operation, the apparatus 1 collides with the righthand bar shown by an imaginary line in Figure 1. Next operation becomes impossible unless the apparatus 1 is rotated backward namely counterclockwise--to the original position. Therefore, the disengagement handling between ratchet claw 11 and cogs 12 must be done during the tightening operation once or several times. The disengagement apparatus 15 is necessary for the same reason.Moreover, it is convenient that the rotation adjustment device 7 is composed of the worm 24, the worm gear 26 and the knob 25, because pulling the lever 82 of the disengagement device 1 5 by his right hand, the operator can rqtate the knob 25 by his left hand till the tightening apparatus 1 goes back to the original arrangement. Because worm gear system has a well-known function of multiplication of force, the heavy tightening apparatus 1 can be turned by a weak force of his fingers acting on the knob 25.

As demonstrated above in detail, by this invention it becomes easy to couple two bars with several nuts firmly. The combination of a linearly driving apparatus and a ratchet device produces a powerful torque for tightening in spite of the smaller size of the apparatus than that of rack type apparatus. As a linearly driving apparatus can be short, the whole apparatus becomes light and handy.

Because the main body 2 is separable, the apparatus 1 can be fitted on the nuts or be slipped thereof very facily. Operation efficiency is very good.

Moreover if the linearly driving apparatus is separable from the main body like this èmbodiment, it is convenient to convey it to a workshop on a high building as it can be lifted up as separated parts individually.

It is more profitable if a hydraulic cylinder of mono-drive type with return spring is used as a linearly driving apparatus, because it is cheap and light.

In the invention the apparatus can easily be turned to the original arrangement by the disengagement device and the rotation - adjustment device. If some obstacles stand near the bar to be coupled, the operation is not disturbed.

This invention has a wide scope of application to couple two bars with male screws. For example, it is utilizable for a lock bolt, an earth anchor, a tie rod and a reinforcing iron bar.

Claims (14)

Claims

1. A method for tightening two nuts in a combination of two bars which have a whole surface or a partial surface with male screws by a tightening apparatus, hanging a first spanner member upon a nut, fitting a second spanner member upon another nut, driving a linearly driving apparatus to turn said second spanner member relative to a main body by a ratchet device, returning said linearly driving apparatus to an original state, and repeating said driving and said returning operations to tighten the nuts.

2. A method for tightening as claimed in claim 1, including during the tightening operation, the step of returning said tightening apparatus to an original arrangement, and beginning said repetition of said driving and said returning operations.

3. A tightening apparatus comprising: a first main body, a second main body fixed to the first main body to prevent any relative rotation between the bodies, a first spanner member located in the first main body; a second spanner member rotatably mounted in the second main body about a first axis and having a spanner portion in its inner surface and ratchet cogs in its outer surface; a carrier slidably mounted in the second main body, a ratchet claw pivoted on the carrier and adapted to engage with said ratchet cogs, resilient means connecting said ratchet claw and said carrier to urge said ratchet claw toward said ratchet cogs, and a linearly driving apparatus operative to drive said carrier in a direction such that the ratchet claw rotates said second spanner member.

4. Tightening apparatus as claimed in claim 3, wherein the second main body is removably fixed to the first main body.

5. Tightening apparatus as claimed in claim 3 or claim 4 wherein the first spanner member is rotatably mounted in the first main body about said first axis and further including a rotation adjustment device operative to rotate the first spanner member and hold it at a selectable position relative to the first main body.

6. A tightening apparatus as claimed in claim 5 wherein said rotation adjustment device comprises a worm rotatatively mounted in the first main body, a worm gear formed on the outer surface of said first spanner member.

7. A tightening apparatus as claimed in claim 5 or claim 6 further including a disengagement device for disengaging said ratchet claw out of said ratchet cogs.

8. A tightening apparatus as claimed in claim 7 wherein the disengagement device comprises a pin pivoted at a portion of said second main body, an operating lever affixed at one end of said pin, and an arm fixed to the pin to push the ratchet claw against the elastic force of said resilient means.

9. A tightening apparatus as claimed in any one of the preceding claims when dependent on claim 4 wherein said first main body can be separated from said second main body in a direction along said axial line.

10. A tightening apparatus as claimed in any one of the preceding claims wherein said linearly driving apparatus is separable from said second main body.

11. A tightening apparatus as claimed in any one of the preceding claims the linearly driving apparatus includes a hydraulic cylinder.

12. A tightening apparatus as claimed in claim 3 wherein said linearly driving apparatus includes reduction gears, and an electric motor or a hydraulic motor for driving said reduction gears.

13. A tightening apparatus as claimed in any one of the preceding claims including a return spring for returning said carrier to an original position.

14. A tightening apparatus substantially as hereinbefore described, with reference to, and as illustrated in, the accompanying drawings.