US3712098A

US3712098A - Pulley forming mechanism

Info

Publication number: US3712098A
Application number: US00162867A
Authority: US
Inventors: S Shaffer; E Scott
Original assignee: Arrowhead Engineering Corp
Current assignee: Arrowhead Engineering Corp
Priority date: 1971-07-15
Filing date: 1971-07-15
Publication date: 1973-01-23
Anticipated expiration: 1990-01-23
Also published as: CA938431A

Abstract

A machine for forming pulleys from a disc shaped metal blank in which the blank is clamped between two rotating backer blocks and one or more tool means are used to split the periphery of the disc shaped blank and to press the flanges formed by the split laterally to form a belt groove. Each backer block contains an annular resilient member adjacent the periphery on the surface facing the opposite backer block. The resilient members permit the pulleys to be formed from material having wide tolerances with respect to material thickness without changing the critical dimensions on the belt groove or resulting in eccentric or wobbly pulley structures.

Description

Shaffer et al.

[54] PULLEY FORMING MECHANISM [75] Inventors: Samuel Ralph Shaffer, Jeffersonville; Earl D. Scott, Walkerton, both of Ind.

[73] Assignee: Arrowhead Engineering Corporation, Knox, Ind.

[22] Filed: July 15, 1971 [21] Appl.No.: 162,867

[52] US. Cl ..72/71, 29/159 R, 72/466 [51] Int. Cl. ..B2lh H04 [58] Field of Search....72/7l, 82, 396, 466; 29/159 R [56] References Cited UNITED STATES PATENTS 3,188,843 6/1965 Romano ..72/466 3,225,425 12/1965 Skinner et al ..72/71 1 Jan. 23, 1973 Primary Examiner-Lowell A. Larson Attorney-Marmaduke A. Hobbs et al.

ABSTRACT A machinefor forming pulleys from a disc shaped metal blank in which the blank is clamped between two rotating backer blocks and one or more tool means are used to split the periphery of the disc shaped blank and to press the flanges formed by the split laterally to form a belt groove. Each backer block contains an annular resilient member adjacent the periphery on the surface facing the opposite backer block. The resilient members permit the pulleys to be formed from material having wide tolerances with respect to material thickness without changing the critical dimensions on the belt groove or resulting in eccentric or wobbly pulley structures.

15 Claims, 6 Drawing Figures PATENTEDJAH23 ms 3.712.098

sum 1 [IF 2 24 INVENTO 6. RALPH SHAFF EARL 0. scorr Mv /zLW AT TORNEXS PATENTEDJMMB v 3,712,098

SHEET 2 [1F 2 EEl- I I 58 g 5 I! 58 f 1 INVENT S S. RALPH SHAF EA/PL D. SCOTT ATTORNEYS PULLEY FORMING MECHANISM ln the fabrication of pulleys from disc shaped metal blanks using a splitting or a slitting and flange spreading operation, a circular tool with a sharp edge slits the periphery of the blank as it is being rotated and, while the first tool is in operation, a second tool enters the slit, preferably from the side of the machine opposite the slitting tool, and spreads the flanges laterally away from the sides of the slitting tool and simultaneously counteracts or balances the forces applied by the slitting tool to the blank and the spindle of the machine. In the machine for performing this operation, backer blocks on the head and tail pieces on the aligned spindles are utilized to give support to the blank and the flanges as they are being formed and to give the final external shape and size to the flanges, usually in cooperation with the spreading tool or with an ironing tool which follows in an overlapping relationship the operation of the slitting and spreading tools. This method and machine perform satisfactorily to produce consistently good pulleys under most operating conditions and with standard material; however, the backer blocks are of rigid metal construction and the slitting, spreading and ironing tools are rigid, and any appreciable excess in thickness of the metal disc shaped blanks, over the normal tolerances, results in imperfections in the final pulley, in that the excess metal of the thicker blanks appears on the inside of the flanges and alters the size and shape of the belt groove. Aside from the change in the critical dimensions of the belt groove, the thicker blanks also cause slightly deformed and sometimes eccentric pulleys which wobble and must be scrapped. It is therefore one of the principal objects of the invention to provide a mechanism for use in fabricating pulleys from disc shaped blanks which will accept blanks ofexcess thickness and produce satisfactory pulleys within acceptable critical tolerances in the groove size and shape, and which will operate satisfactorily over a wide tolerance range in blank dimensions and permit the formation of increased groove sizes and different groove configurations without increasing stock thickness.

Another object of the invention is to provide a mechanism for use in a machine for producing pulleys, sheaves and like articles by splitting a rotating disc shaped blank, which permits the groove to be formed consistently, regardless of thickness of the material of the blank, and which will produce concentric and balanced pulley and sheave structures irrespective of the variations in blank thickness.

A further object of the invention is to provide, in a sheave fabricating machine of the aforesaid type, yieldable backer blocks against which the flanges ofthe pulleys are formed (luring the splitting or flange spreading operation, and which are provided with a resilient layer of material capable of yielding sufficiently to absorb or accommodate variations in the thickness of the metal in the flanges resulting from variations in the thickness of the blanks.

Still another object of the invention is to provide a spindle structure including backer blocks for a pulley fabricating machine, which permits effective control of the flange forming operation, reduces the set-up time necessary to place the machine in production, and permitscloser adherence to wobble and eccentricity tolerances, and which simplifies tool design, installation and maintenance and minimizes down-time.

Additional objects and advantages of the invention will become apparent from the following description and accompanying drawings, wherein:

FIG. 1 is a transverse cross sectional view through the present pulley forming mechanism, showing two tools preparatory to the pulley forming operation;

H6. 2 is an elevational view of one of the backer blocks shown in FIG. 1, the elevation being indicated by lines2 2 ofFlG. 1;

FIG. 3 is a transverse cross sectional view similar to that shown in FIG. 1, showing the position of the two tools upon the completion of the slitting and flange expanding operations performed by the two tools;

FIG. 4 is a transverse cross sectional view similar to those of FIGS. 1 and 3, but showing a third tool performing a bead-forming operation following the completion of the steps exemplified in FIGS. 1 and 3;

FIG. 5 is a transverse cross sectional view through a pulley forming mechanism embodying a modified form of the present concept; and

FIG. 6 is a transverse cross sectional view similar to those of the preceding figures illustrating a further modified form of the present concept, showing two tools preparatory, to the slitting and flange expanding operations.

Referring more specifically to the drawings, numeral 20 designates the present pulley or sheave forming mechanism for use in a machine having head and tail spindles, one or both of which are power driven for rotating a blank 22 as it is held between

backer blocks

24 and 26 rotatably mounted on the opposed axially aligned spindles while the operation is performed for forming the two

flanges

27 and 28 of the pulley or sheave 29 made from blank 22. The blank is slit by a slitting tool 30,and the two flanges formed by the slitting tool are spread laterally by a spreading tool 32. These two tools are circular in shape and are rotated as they are advanced into the periphery of blank 22. As can be seen from the relative position of tool 30 and tool 32 with reference to the periphery of the blank, tool 30 penetrates the periphery in advance of tool 32; however, the two tools perform in a simultaneous overlapping relationship, with the flange spreading tool operationally following the slitting tool until the slitting tool has reached its innermost position, where it normally dwells until the spreading tool has reached its innermost position, both positions being substantially the same distance from the axial center of the

blocks

24 and 26. The machine in which the present mechanism is normally used is illustrated in US. Pat. No. 3,370,447 issued to William .I. Skinner and Earl D. Scott and assigned to Arrowhead Engineering Corporation. The method performed by the machine is disclosed and claimed in US. Pat. No. 3,225,425 issued to William J. Skinner and Earl D. Scott, and consists in rotating a disc shaped blank clamped between two ration by a tool 34 such as illustrated in FIG. 4 herein.

One of the important features of the process covered by the latter two patents is the simultaneous slitting and spreading steps performed by two

separate tools

30 and 32, with the spreading tool following closely the inward movement of the slitting tool and being operated in overlapping relation with the slitting tool.

In the machine incorporating the present pulley forming mechanism, a disc shaped blank is inserted in the machine and the three forming tools are progressively and simultaneously advanced in overlapping relationship to perform the three foregoing operations. The pulley or sheave fabricated by the present machine is provided with a hub, either formed integrally with or joined rigidly to the center portion of the disc shaped blank after the fabricating operation has been completed, one suitable hub construction being disclosed and claimed in U.S. Pat. No. 3,225,614.

The principal operating mechanism consists of head and

tail spindles

35 and 36 mounted in the machine, and the two spindles are rotated, normally one spindle being driven by a power transmission mechanism and the other spindle being driven indirectly through blank 22 from the driven spindle. The tail spindle is reciprocated toward and away from the head spindle as the blank is inserted therebetween and the formed pulley or sheave removed therefrom.

Backer blocks

24 and 26 are mounted on the tail and head spindles, respectively, and secured thereto by screws or other suitable securing means extending into

bores

37 and 38 in

backer blocks

24 and 26. The

tools

30 and 32 are generally disc shaped and rotate while they are performing the slitting and spreading operations, but are not normally power driven aside from the power required to produce rotation of the blank, so that instant forming takes place as soon as the tool engages the periphery of the blank. While in the embodiment referred to herein, the head and tail spindles and the respective backer blocks are positioned on a vertical axis, they may be positioned on a horizontal axis, and the head spindle may be withdrawn from the tail spindle while the tail spindle remains in fixed translatory position, or both the head and tail spindles may be moved axially to open and close when receiving blanks and discharging formed pulleys or sheaves. Description in greater detail of the machine will not be included herein, since reference to the two prior patents will furnish the complete mechanism for driving the

backer blocks

24 and 26 and the mechanism for rotatably supporting, advancing, and retracting the three

tools

30, 32 and 34. While the foregoing machine as generally described will perform satisfactorily to produce high quality pulleys and sheaves, provided'the thickness of the blank can be adequately controlled, i.e. the thicknesses be maintained within specified tolerances, there is often a deviation in the thickness of the blanks, and hence the prior mechanism involving the backer blocks shown in the aforementioned patents will result in a variation in the size of the groove, and sometimes result in wobble or other eccentricity in the pulley or sheave.

The internal dimensions of the pulley groove 40 are critical whereas the external dimensions of the flanges are usually not critical. The present invention is directed to a mechanism having backer blocks which permit accurate adherence to internal groove dimensions without the necessity of accurately controlling the tolerances of the blank thickness. ln order to accommodate the excess meta on the thicker blanks 22 without changing the dimensions of belt groove 40 or causing eccentricity or wobbling, an annular insert 50 of resilient material such as firm rubber, i.e. of relatively high durometer, is seated in an annular recess 52 in the peripheral margin in the face of each

backer block

24 and 26, i.e. on opposite sides of blank 22. The recess and the resilient insert extend inwardly to approximately the bottom of the outside portion of

flanges

27 and 28 and the insert is secured in place with cement or any other suitable securing means so that the insert will remain firmly in place in the annular recesses 52. A compressible plastic material may be used in place of rubber, and synthetic rubber or other rubber-like material may be suitable under most operating conditions. The resilient insert may be replaced from time to time as wear occurs during the operation of the machine; however, some wear can occur in the rubber without affecting the critical size and shape of the groove and internal dimensions of the flanges, in that the resilience of the material compensates for the wear ofthe inserts as well as the variations in thickness of the blank.

In the operation ofthe present mechanism in a pulley fabricating machine such as the one referred to herein, a disc shaped blank is inserted in the mechanism between

backer blocks

24 and 26 in the position shown in FIG. 1. The two or three

tools

30, 32 and 34 are advanced progressively inwardly, with the slitting tool 30 contacting the periphery first and slitting the peripheral edge on the blank. As it advances inwardly, the flange spreading tool 32 enters the slit made by tool 30, pressing the flanges laterally away from the sides of tool 30 so that tool 30 performs merely the slitting function of separating the metal at the base ofthe flanges as they are being formed. The two

tools

30 and 32 are preferably disposed diametrically opposite from one another, although tool 32 may be spaced at some other angular position from tool 30, and/or two of such tools 32 may be spaced equally on either side of a line projected diametrically opposite from too] 30 so that the pressure applied by tool 30 is countered by a balanced relationship between tool 30 and one or two of tools 32. Tool 34 may be positioned at right angles to the other two tools or it may be so located that the three tools are equally spaced from one another around the periphery ofthe blank.

As the blank is slit and the flanges formed, the flanges are pressed laterally by tool 32 until the external sides of the flanges contact the surfaces of inserts 50 of the two

backer blocks

24 and 26. When the slitting tool 30 has completed its slitting operation, it may dwell at the base of the flanges or may be withdrawn; however, normally it is retained at the base of the flanges until the final phase of the inward movement of tool 32 has been completed. As tool 32 reaches its innermost position, the flanges are pressed firmly against and at least slightly into the resilient inserts 50, thus forming groove 40 of the proper size and shape regardless of any normal deviation from the tolerance thicknesses of the blanks. As tool 34 completes its inward movement which is partially performed simultaneously with the operation of

tools

30 and 32, the final shaping of the groove takes place and

beads

46 and 48 are formed at the periphery of the two flanges. At the completion of the final forming step by tool 34, the three tools are withdrawn from their innermost position to the original starting position illustrated in FIG. 1, and the backer blocks are retracted and the newly formed pulley is discharged from the mechanism. A new blank is then inserted between the backer blocks and clamped therebetween, and the operation described hereinabove is again performed.

In the embodiment of FIG. 5, backer blocks 54 and 56 have resilient inserts, an annular recess 58 and a resilient layer 60 secured to surface 62 by a suitable securing means. The resilient insert is preferably of firm rubber or rubber-like material, although a plastic material may be used. The backer blocks are mounted in the machine in the same manner previously described herein for backer blocks 24 and 26, and

tools

30, 32 and 34 are operated in the same manner as previously described, initially slitting the periphery of blank 22 and pressing the flanges laterally in engagement with resilient inserts 60. The forming tool is preferably operated simultaneously in an overlapping relationship with

tools

30 and 32 to produce the final shape of the grooves. The inserts of resilient material are relatively thin and can be compressed sufficiently to accommodate and absorb the excess metal of the thicker blanks.

The modification illustrated in FlG. 6 is somewhat different in that an insert 68 of relatively resilient material is seated in annular slots 70 of backer blocks 64 and 66 and secured therein by cement or other suitable securing means. ln this modification the insert is relatively resilient and is in contact with the blank before the operation is commenced. As the flanges are formed by the three tools, they are compressed laterally into the resilient material, which constantly urges the flanges into engagement with

tools

32 and 34 so that the groove dimensions will be effectively controlled by the dimensions and contour of

tools

32 and 34. The inserts of this modification are of substantially greater resilience than the inserts of the previously to be compressed sufficiently from the position shown in FIG. 6 to the final stage when the flanges are pressed fully laterally, as seen in FIG. 4.

The resilient inserts in the backer blocks described and illustrated herein permit better control of the wall thickness of the pulley groove area, shorter set-up time required toplace the machine in operation, and less down-time for fine adjustment of the machine to various thicknesses of pulley and sheave blanks. The resilient insert will also give complete support to the blank in the-final stages, regardless of the thickness of the material in the blanks,.and hence assist in forming true, wobble-free, concentricpulleys and sheaves. The present concept permits an increased groove size and different configurations over those which are now possible, without increasing stock thickness, and permits .greater latitude in the tolerances of the backer blocks and blank material.

Although three modifications of the present invention have been described in'detail herein, various other modifications and changes may be made without departing from the scope of the invention.

We claim:

described embodiments, in order to permit theinserts 1. A mechanism for forming pulleys from a disc shaped metal blank by slitting the periphery and spreading the flanges formed by the slit, comprising two axially aligned rotatable backer blocks for clamping disc shaped blanks in axial alignment therebetween for rotation therewith, each of said backer blocks having a resilient annular member adjacent the periphery thereof in the surface facing the other backer block, said resilient members being compressible by the flanges formed on said disc shaped blank.

2. A mechanism for forming pulleys as defined in claim 1 in which each backer block is constructed of steel and contains an annular groove extending inwardly from the periphery thereof adjacent the face of the other backer block, said groove containing said resilient annular member.

3. A mechanism for forming pulleys as defined in claim 2 in which each backer block is constructed of steel and contains an annular groove of L-shaped cross section extending inwardly from the periphery thereof adjacent the face of the other backer block, and said resilient annular member is disposed in said groove and sloping outwardly away from the clamping face of the block contacting the blank.

4. A mechanism for forming pulleys as defined in claim 2 in which said groove extends inwardly from the periphery of the backer blocks to approximately a depth equal to the depth of the split in the blank.

5. A mechanism for forming pulleys as defined in claim 1 in which the surfaces of said resilient members are tapered angularly away from the clamping surface of the block facing the other backer block.

6. A mechanism for forming pulleys as defined in claim 3 in which the surfaces of said resilient members are tapered angularly away from the clamping surface of the block contacting the blank.

7. A mechanism for forming pulleys as defined in claim 1 in which said resilient annular members are constructed of rubber-like material of relatively high durometer.

8. A mechanism for forming pulleys as defined in claim 1 in which the surface of said resilient annular member extends substantially radially outwardly on a plane with the clamping surface facing the other backer block.

9. In a machine for forming pulleys from a disc shaped metal blank using a tool means to split the periphery of the blank and spread the flanges laterally to form a belt groove; two axially aligned rotatable backer blocks for clamping disc shaped blanks in axial alignment therebetween for rotation therewith, each of said backer blocks having a yieldable annular member adjacent the periphery thereofon the surface facing the other backer block, for engagement by the flanges formed on said disc shaped blank by said tool means.

10. A mechanism for forming pulleys as defined in claim 9 in which each backer'block is constructed of steel and contains an annular groove extending inwardly from the periphery thereof adjacent the face of the other backer block, said groove containing said yieldable annular member.

11. A mechanism for forming pulleys as defined in claim 10 in which said groove extends inwardly from the periphery of the backer blocks to approximately a depth equal to the depth of the split in the blank.

14. A mechanism for forming pulleys as defined in claim 9 in which said resilient annular members are constructed of rubber-like material of relatively high durometcr.

15. A mechanism for forming pulleys as defined in claim 9 in which the surface of said resilient annular member extends directly radially outwardly.

Claims

1. A mechanism for forming pulleys from a disc shaped metal blank by slitting the periphery and spreading the flanges formed by the slit, comprising two axially aligned rotatable backer blocks for clamping disc shaped blanks in axial alignment therebetween for rotation therewith, each of said backer blocks having a resilient annular member adjacent the periphery thereof in the surface facing the other backer block, said resilient members being compressible by the flanges formed on said disc shaped blank.

9. In a machine for forming pulleys from a disc shaped metal blank using a tool means to split the periphery of the blank and spread the flanges laterally to form a belt groove: two axially aligned rotatable backer blocks for clamping disc shaped blanks in axial alignment therebetween for rotation therewith, each of said backer blocks having a yieldable annular member adjacent the periphery thereof on the surface facing the other backer block, for engagement by the flanges formed on said disc shaped blank by said tool means.

10. A mechanism for forming pulleys as defined in claim 9 in which each backer block is constructed of steel and contains an annular groove extending inwardly from the periphery thereof adjacent the face of the other backer block, said groove containing said yieldable annular member.

12. A mechanism for forming pulleys as defined in claim 10 in which the surfaces of said resilient members are tapered angularly away from the clamping surface of the block contacting the blank.

13. A mechanism for forming pulleys as defined in claim 11 in which the surfaces of said resilient members are tapered angularly away from the clamping surface of the block contacting the blank.

14. A mechanism for forming pulleys as defined in claim 9 in which said resilient annular members are constructed of rubber-like material of relatively high durometer.