US2887277A - Refiner control system - Google Patents

Description

19, 1959 e. SAKATA ETAL 2,887,277

REFINER coumor. SYSTEM Filed March 18, 1957 FIG-2 INVENTORS GEORGE SAKATA 8 JAMES D. POWERS ATTORNEYS United States Patent REFINER CONTROL SYSTEM George Sakata and James D. Powers, Middletown, Ohio, assignors to The Black-Clawson Company, Hamilton, Ohio, a corporation of Ohio Application March 18, 1957, Serial No. 646,694

6 Claims. (Cl. 241-256) This invention relates to apparatus for controlling the operation of refiners such as Jordans, attrition mills and the like having juxtaposed relatively rotating refining elements.

The'invention has special relation to control of the axial adjustment of the relatively rotating refining elements in a refiner provided with a motor driven adjusting mechanism for regulating the relative axial positions of the refining elements in accordance with desired refining conditions as measured by the load imposed on the drive motor of the refiner. In apparatus of this character, the proper load on the refiner motor for desired refining conditions may be predetermined by the operator, and the axial positions of the refining elements are adjusted accordingly, which may be done automatically by suitable controls responsive to change in the load conditions to actuate an adjusting motor or which may be effected by manually operating control switches for the adjusting motor in accordance with observed changes in the load conditions. Thus at the start of a refining operation in a Jordan or like conical refiner, the plug is usually at its greatest spacing outwardly of the shell, and is gradually advanced into closer spacing with the shell as the refining proceeds.

At the conclusion of a batch refining operation, it is important before the next operation begins to retract or separate the refining elements a sufficient distance to prevent overloading the refining motor at the start of the next operation, since if there is insufiicient clearance therebetween when the refiner is again started, the resulting high starting torque may burn out the motor. However, since an adjusting mechanism for this purpose is commonly so geared that a considerable time interval is required to produce a relatively small axial movement of the parts, in order to assure adequately precise adjustment of their positions in operation, it is desirable to limit retraction of the parts to a relatively small axial distance because over-travel beyond the essential minimum distance results in lost time for resetting at the start of the next batch. On the other hand, since the axial positions of the parts at the conclusion of a given operation is variable, being subject to change by any of several factors including the nature of the stock, the degree of refining desired, andwear of the working surfaces of the refining elements requiring compensatory adjustment, the position to which the retractable member should be retracted is similarly variable.

The present invention relates to a control device for the relatively rotating refining elements of a refiner of the above character which will control adjustment of the parts following a refining operation in such manner as to assure retraction or separation thereof to substantially the minimum proper distance for the start of the next operation irrespective of the extent of the advancing movement of the parts during the previous operation from their starting positions and irrespective of whether the previous advancing movement was occasioned'by change in consistency or freeness of the stock reflected by reduc- A device for this purpose is shown in Croake et a1.

Patent 2,642,781, issued June 23, 1953, to the assignee of the present application, and many devices in accordance with that patent have proved successful in commercial installations. It is a primary object of the present invention to provide a device for the same purpose which is of improved and greatly simplified construction as well as simpler to install, and which will at the same time operate with similarly assured accuracy and reliability over a long service life.

Another object of the present invention is to provide such a control device which has additional practical advantages of being quickly and easily adapted to use with existing adjusting mechanisms for cooperation therewith and with minimum requirements of modification of the existing structure.

It is also an object of the invention to provide such a control device wherein all of the operating parts are mounted upon a single base plate which may be employed as a bearing cover or similar member in conjunction with a drive shaft forming a part of a refiner adjusting mechamsm.

Additional objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings:

Fig. 1 is a schematic view illustrating the operation of the control device of the invention in conjunction with a conical refiner having a motor driven unit for adjusting the axial position of the plug in accordance with the load on the refiner motor;

Fig. 2 is an enlarged sectional view taken on the line 22 of Fig. 4 and showing in detail the control device of the invention;

Fig. 3 is a section on the line 33 of Fig. 4;

Fig. 4 is a view in radial section taken as indicated by the line 4-4 of Fig. 2 and Fig. 3; and

Fig. 5 is a fragmentary view taken as indicated by the line 55 of Fig. 4.

Referring to the drawing, which illustrates a preferred embodiment of the invention, Fig. 1 shows a schematic arrangement of control apparatus for a conical refiner 10 of the Jordan type which is provided with a drive motor 11 for rotating the conical plug 12 on shaft 13 in a shell 14 having inlet and discharge pipes 15 and 16, respectively. The axial position of the plug in the shell is controlled by an adjusting unit indicated gen-- erally at 20 and which is shown as of the construction disclosed in Staege et al. Re. 24,185, issued July 24, 1956 to the assignee of the present application. As disclosed in that patent, this unit 20 includes a housing 21 and a motor 22 whichoperates through a worm gear 23 to drive a shaft 25 having a threaded portion 26 at one end in threaded engagement with a part of the thrust bearing assembly for the plug shaft 13 indicated diagrammatically at 27, which corresponds to the part 44 in Patent Re. 24,185 and also to the part 26 in the above Croake et al. patent. Rotation of shaft 25 will accordingly produce axial movement of the shaft 13 and the adjusting unit 20,

The operation of the motor 22 of adjusting unit 20 is controlled by circuits indicated diagrammatically at 30 to actuate motor 22 in accordance with changes in the load condition on the refiner motor 11, as disclosed in detail in the above Patent Re. 24,185. The control,

circuits 30 cooperate with a normally open switch 31 Patented May 19, 1959 which completes a circuit for energizing motor 22 in the direction to retract the plug 12, and this circuit includes a limit switch 33 which has an operating arm 35 and is effective when open to terminate operation of motor 22 in the direction causing retraction of the plug with respect to shell 14. The switch 31 corresponds to the switch 121 in the Staege et al. patent and the switch 42 in the Croake et al. patent, and similarly the switch 33 corresponds to the switch 50 in the Staege et 211. patent and the switch 44 in the Croake et a1. patent. A normally open manual switch 36 is also shown as connected in parallel with switch 33 to close the retracting circuit for motor 22 when switch 33 is open in order to retract the plug 12 to a greater extent than would be effected by the limit switch 33.

The present invention provides simple and easily adjustable means for operating the switch 33 during retraction of plug 12 by motor 22 when a predetermined extent of retracting movement of the plug has occurred. More specifically, the control of the invention is such that when the switch 33 is closed, it provides for a predetermined range of retracting movement of the plug from a reference position such, for example, as its position of effective contact between the refining surfaces of the plug and shell. When the plug has retracted over the predetermined range from the selected reference position, switch 33 will open to stop further operation of motor 22 in the direction to retract the plug.

Referring more specifically to Figs. 2-5, the control device of the invention is enclosed by the end cover 39 for the housing 21 and includes a base plate 40 which may be mounted on the bearing housing 29 to serve as a cover or cap for bearing 28. The switch 33 is also mounted on the plate 40 by means of a bracket 41, and this bracket is slotted at 42 lengthwise thereof to provide for adjusting the position of the mounting screws 43 for switch 33 as pointed out in more detail hereinafter.

The arm 35 of switch 33 is operated by a cam 44 which is shown as having a single high step 45 and low step 46. The cam 44 is secured as by welding to a plate or strap 50 which is in turn mounted for movement axially of shaft by means of a pair of studs or pins 51 mounted in base plate 40 and slidably received in a pair of through bores 52 adjacent opposite ends of strap 50. Each of the pins 51 carries a pair of light compression springs 53 and 54 located on opposite sides of the strap 50 to provide opposed biasing forces efiective on the strap.

A driving connection is provided between the shaft 25 and the cam 44 for causing actuation of switch 33 to stop operation of motor 22 in the direction of retract plug 12 after the desired predetermined maximum extent of such retracting movement. A stud 60 is threaded or otherwise mounted at 61 coaxially on the end of shaft 25 and projects through a central aperture in the base plate 40 which is shown as provided with a suitable seal 62. The stud 60 is provided near its outer end with a threaded portion 65 of limited axial extent which is adapted to engage the complementary tapped bore 66 in the strap 50. The land portions 67 and 68 of stud 60 on either side of the threaded portion 65 are of sufiiciently reduced diameter to pass slidably through the bore 66.

. With this construction, the strap 50 is in effect a nut with respect to the stud 60 but is supported for guided non-rotary movement by means of the pins 51, and the stud 60 is in effect an extension of shaft 25, which it could actually be except that the use of the smaller tially separate stud is somewhat simpler. When the stud 60 is rotated in clockwise direction as viewed in Fig. 4, the nut 50 will engage and traverse the threaded portion 65 until it reaches the land 68, and if the stud continues to revolve, the nut will simply track or slip on the stud since it is held in abutting relation with the outer end of threaded portion 65 by the springs 54. Then whenever the stud reverses its direction of rotation, the nut 50 will again engage and traverse the threaded portion 65 until it returns to the position shown in Fig. 2, and during the continued rotation of stud 60 in the same direction, the nut will slip on the land 67 while it is held against the threaded portion 65 by the springs 53.

In the operation of the invention with the refiner adjusting unit as shown in Fig, l, the contacts of switch 33 are indicated as closed when the switch arm 35 is engaged by the low step 46 of cam 44 and held open when the arm 35 is engaged by the high cam step 45. If the threaded portion 26 of shaft 25 is a normal right hand thread, rotation thereof in clockwise direction as viewed in Fig. 4 will retract plug 12, and rotation in the opposite direction will advance the plug. The movements of nut 51) will correspond to those of the plug if the threaded portion 65 is similarly of right hand thread as shown, and therefore the extent of retraction of the plug provided for by the control of the invention is determined by the extent of movement of nut 50 and cam 44 from left to right as viewed in Fig. 2 before the high step 45 of the cam engages and raises switch arm 35 to open the contacts of switch 33.

Under these conditions, a convenient arrangement for reference purposes is to establish the mounting slots 42 in bracket 41 in such location that when the mounting bolts 43 are at the inner ends of these slots, the switch 33 will just be operated by cam 44 in the innermost position of nut 50 shown in Fig. 2. The maximum retraction of the plug will then be determined by the extent to which the bolts 43 are moved outwardly in slots 42. For example, if they are moved Ms inch, the nut 50 will be able to retract inch before cam 44 actuates switch 33, and this will provide for a proportional extent of retraction of plug 12 which depends upon the ratio of the threaded portions 65 and 26. For example, if the threaded portion 26 has 4 threads per inch and the portion 65 has 8 threads per inch, this As inch adjustment will provide for 4 inch retraction of the plug 12 from its position of maximum advance in shell 14, which is ample for normal operating conditions.

If it is desired at any time to retract the plug beyond the extent permitted by switch 33, this can be done mechanically by actuation of switch 36 or manually by means of the hand wheel provided on the unit 20 as shown in Patent Re. 24,185. During such further movement, the nut 50 will travel to the land 68 and slip thereon until the drive is reversed. Thereafter the springs 54 will cause nut 50 to reengage the threaded portion 65 and travel in the opposite direction until it reaches the land 67. If the starting position is such that the plug can advance in the shell beyond the point at which nut 50 reaches the land 67, the nut will slip on the stud during further rotation of shaft 25, but as soon as the drive is reversed, the nut will begin to traverse the threaded portion 65 in the opposite direction until cam 44 actuates switch 33.

The range of retraction established by the adjusted position of switch 33 as described, will apply whenever the plug begins to retract. This is an important advantage because during a batch refining operation, the plug will tend to move inwardly of the shell as the operation proceeds because its position is determined by the load on the refiner motor, and since this load would decrease during refining if the position of the plug were fixed, the plug is caused to move in by the unit 20' in order to maintain the same load conditions. Therefore, the

position of the plug at any instant during a batch refin-- ing operation corresponds to the maintained maximum load conditions, and the control of the invention provides for retraction of the plug through the desired range from each such position of maximum load.

The devices of the invention also offers substantial advantages from the standpoint of economy of production and also ease of applicability to existing refiner adjusting units."v Thus since the mounting plate 40 is shown installed as a bearing cover in the adjusting unit of PatentRe. 24,185, it will be apparent that the device olf Ithe invention is easily and quickly applied to such units, ,Furthermore, the same type of installation can beimadefiniother units including a rotary drive shaft having 'a bearing 'at one end without modification of the dev'ice'other than perhaps to change the dimensions of the base plate 40 in accordance with the. design of the particular unit which is to be installed.

While the 'form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

, :What is claimed is:

1; A'contr'ol for a refiner of the character described having relatively rotating refining elements, a drive for advancing and retracting one of said elements axially with respect to the other while said refiner is in operation, a switch for controlling said drive in the direction to retract said one refining element, comprising a base, means for supporting said switch in fixed position on said base, a shaft supported in fixed axial relation with said base for rotation by said drive, a cam for mechanically operating said switch to stop said drive, a support for said cam including a nut, said shaft having thereon a portion of limited axial extent threaded for engagement by said nut, said shaft having land portions on either side of said threaded portion of reduced diameter receiving said nut slidably thereon, means carried by said base for biasing said nut in both directions axially of said shaft to cause said nut to engage and traverse said threaded portion of said shaft each time said drive reverses its direction and thereafter to slip relative to said shaft during further rotation thereof in the same direction, and means for adjusting the relative positions of said switch and said threaded shaft portion axially of said shaft to effect operation of said shaft by said cam following a predetermined extent of rotation of said shaft by operation of said drive in the direction to retract said one refining element.

2. A control for a refiner of the character described having relatively rotating refining elements, a drive for advancing and retracting one of said elements axially with respect to the other while said refiner is in operation, a switch for controlling said drive in the direction to retract said one refining element, comprising a base, a shaft supported in fixed axial relation with said base for rotation by said drive, a cam for mechanically operating said switch to stop said drive, means supporting said cam for guided movement parallel with said shaft, a nut fixed to said cam, said shaft having thereon a portion of limited axial extent threaded for engagement by said nut, said shaft having land portions on either side of said threaded portion of reduced diameter receiving said nut slidably thereon, means carried by said base for biasing said nut in both directions axially of said shaft to cause said nut to engage and traverse said threaded portion of said shaft each time said drive reverses its direction and thereafter to slip relative to said shaft during further rotation thereof in the same direction, and means for mounting said switch on said base in adjustably fixed relation with said shaft providing for operation thereof by said cam following a predetermined extent of rotation of said shaft by operation of said drive in the direction to retract said one refining element.

3. A control for a refiner of the character described having relatively rotating refining elements, a drive for advancing and retracting one of said elements axially with respect to the other while said refiner is in operation, a switch for controlling said drive in the dithereon a threaded portion of limited axial extent for engagement with said nut member and having land portions on either side of said threaded portion of reduced diameter to receive said nut member slidably thereon, means for exerting a biasing force effective between said nut member and said stud member in both directions axially of said stud member to cause relative traversing movement of said nut member and said threaded portion of said stud member each time said drive reverses its direction followed by relative slipping therebetween during further operation of said drive in the same direction and thereby to establish a predetermined range of movement of said cam, and means for mounting said switch in adjustably fixed position on said base with respect to said range of movement of said cam to provide for operation thereof by said cam following a predetermined extent of operation of said drive in the direction to retract said one refining element.

4. A control for a refiner of the character described having relatively rotating refining elements, a drive for advancing and retracting one of said elements axially with respect to the other while said refiner is in operation, a switch for controlling said drive in the direction to retract said one refining element, comprising a base, a rotary drive shaft forming a pant of said drive and supported in fixed axial relation with said base, a cam for mechanically operating said switch to stop said drive, a support for said cam including a nut, a stud mounted in axially projecting relation from said drive shaft and having thereon a portion of limited axial extent threaded for engagement by said nut, said stud having land portions on either side of said threaded portion of reduced diameter receiving said nut slidably thereon, means carried by said base for biasing said nut in both directions axially of said stud to cause said nut to engage and traverse said threaded portion of said stud each time said drive shaft reverses its direction of rotation and thereafter to slip relative to said stud during further rotation of said drive shaft in the same direction, and means for mounting said switch on said base in adjustably fixed relation with said stud providing for operation thereof by said cam following a predetermined extent of rotation of said drive shaft in the direction to retract said one refining element.

5. A control for a refiner of the character described having relatively rotating refining elements, a drive including a rotary shaft for advancing and retracting one of said elements axially with respect to the other while said refiner is in operation, a switch for controlling said drive in the direction to retract said one refining element, comprising a base plate adapted to be mounted in close relation with said shaft, a cam for operating said switch to stop said drive, a support for said cam including a nut, a stud connected with said shaft for rotation thereby adjacent said base plate and having thereon a portion of limited axial extent threaded for engagement with said nut, said stud having land portions on either side of said threaded portion of reduced diameter receiving said nut slidably thereon, means on said base plate supporting said nut for guided non-rotary movement axially of said shaft, means carried by said base plate for biasing said nut in both directions axially of said stud to cause said nut to engage and traverse said threaded stud portion each time said drive shaft reverses its direction of rotation and thereafter to slip relative to said stud without axial movement during further rotation of said drive shaft in the same direction,

6 and means on said base plate supporting said switch for adjustment thereon axially of said stud providing for operationthereof by said cam following a predetermined extent of rotation of said drive shaft in the direction to retract said one refining element.

6. A control for a refiner of the character described having relatively rotating refining elements, a drive ineluding a rotary shaft for advancing and retracting one of said elements axially with respect to the other while said refiner is in operation, a switch for controlling said drive in the direction to retract said one refining element, comprising a base plate adapted to be mounted in overlying relation with one end of said shaft and having an aperture therethrough, a cam for mechanically operating said switch to stop said drive, a support for said cam including a nut, a stud adapted to extend through said aperture for mounting on said shaft end for rotation with said shaft, said stud having thereon a portion of limited axial extent threaded for engagement with said nut and having land portions on either side of said threaded portion of reduced diameter receiving said nut slidably thereon, means on said base plate supporting said nut for guided non-rotary movementaxially of said shaft, means carried by said b'as'e'plate for biasing'said nut in both directions axially of said stud to cause said.

nut to engage and traverse'said threaded studlpoi tion each time 'saidrdrive shaft reverses its direction ofro tation and thereafter to slip relative to'said stud with: out axial movement during further rotation of said drive shaft in the same direction, and means on said'base element.

References Cited in the file of this patent; E UNITED STATESIPATENTS i Jones Apr. l9, ;l9 32 Crooke et a1. June '23, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,887,277 May 19, 1959 George Sakata et a1.

It is herebfi certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 52, for "of retract" read to retract column 6, line 60, for for operating read for mechanically operating Signed and sealed this 29th day of September 1959.

(SEAL) Attest:

KARL Ha AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Ofiicer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,887,277 May 19, 1959 George Sakata et al.

It is hereby certified that error appears in the -printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

o retract column Column 3, line 52, for "of retract" read t ically operating 6, line 60, for "for operating read for mechan Signed and sealed this 29th day of September 1959.

(SEAL) Attest: KARL H, AXLINE ROBERT (J. WATSON Commissioner of Patents Attesting Oflicer

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