US3631704A

US3631704A - Apparatus for roll forming toothed workpieces

Info

Publication number: US3631704A
Application number: US2104A
Authority: US
Inventors: John Leonard; Martin S Wenger Jr
Original assignee: Teledyne Inc
Current assignee: Teledyne Inc
Priority date: 1970-01-12
Filing date: 1970-01-12
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04
Also published as: FR2076053B1; SE371118B; GB1298630A; DE2061261A1; FR2076053A1; CA930208A; JPS5220946B1

Abstract

Apparatus for forming toothed workpieces by rolling them in high-pressure contact with a single forming die. The workpieces are held in precise relation with the die during at least the final stage of the rolling operation by a support assembly having one or more pilot surfaces, each pilot surface being in rolling contact with a pair of rigidly mounted backup members. The pilot surface or surfaces and the backup members locate the axis of the workpiece with respect to the axis of the forming roll. Separate support members positively locate the workpiece along its axis during the rolling operation.

Description

United States Patent APPARATUS FOR ROLL FORMING TOOTHED WORKPIECES 3 Claims, 4 Drawing Figs.

U.S. Cl 72/102, 29/1 592 Int. Cl B2lh 5/02 Field of Search 72/ l 02,

I07, 108, 109, HO, lll;29/l59.2

[56] References Cited UNITED STATES PATENTS 3,552,167 l/l97l Bergietal 29/l59.2 3,434,322 3/1969 Cowles et al 72/107 Primary ExaminerL0well A. Larson Attorney-Strauch, Nolan, Neale, Nies & Kurz ABSTRACT: Apparatus for forming toothed workpieces by rolling them in highpressure contact with a single forming die. The workpieces are held in precise relation with the die during at least the final stage of the rolling operation by a support assembly having one or more pilot surfaces, each pilot surface being in rolling contact with a pair of rigidly mounted backup members. The pilot surface or surfaces and the backup members locate the axis of the workpiece with respect to the axis of the forming roll. Separate support members positively locate the workpiece along its axis during the rolling operation.

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SHEET 1 0F 3 INVENTORS JOHN LEONARD MARTIN S. WENGERJR INVENTORS @OHN LEONARD MARTIN s. WENGER, JR

BY I a ATTORN S SHEET 2 UP 3 PATENTED JAN 41972 a 1 L mm a PATENTEUJAN 41972 SHEET 3 [IF 3 INVENTORS JOHN LEONARD MARTIN S. WENGER, JR

APPARATUS FOR ROLL FORMING TOOTIIED WORKPIECES BACKGROUND OF THE INVENTION This invention relates to apparatus for roll forming toothed workpieces and has particular application to the formation of parts, such as automotive transmission gears, which must meet unusually exacting standards for dimensional accuracy and quality of finish. The traditional method of manufacturing such parts by first hobbing a cylindrical blank and forming the part to final dimensions by shaving has now been replaced in many operations by a technique which comprises substituting for the final shaving operation a roll finishing operation. Examples of roll finishing apparatus are disclosed in US. Pat. No. 3,362,059 and in copending application Ser. No. 809,365 filed Mar. 21, 1969 for Apparatus for Roll Forming Workpieces and application Ser. No. 817,669 filed Apr. 21, 1969 for Apparatus for Roll Forming workpieces.

In the apparatus disclosed in the patent, the workpiece is rotatably mounted between a pair of rotating dies, one of which rotates about a fixed axis and the other of which rotates about a laterally displaceable axis. In operation, the moveable die is shifted toward the fixed axis die and the workpiece is engaged under high pressure at peripherally opposed points by the two dies. Despite its many advantages and its excellent performance this type of apparatus is sufficiently expensive to be feasible only in environments where high production rates are the rule. The high cost of the machine is due in part to the requirement for a pair of forming rolls or dies which are exactly matched and which must be installed and operated with the utmost precision to maintain the two dies in matched relationship with the required accuracy.

An important simplification of the prior apparatus is disclosed in the aforesaid copending application Ser. No. 817,669. In the apparatus disclosed therein the workpiece is typically mounted for rotation on a support between a pair of arbors, one of which is driven and carries a forming die or roll. The opposed arbor carries one or more pilot members having essentially cylindrical surfaces which run in rolling contact with the cylindrical surfaces of corresponding pilot members carried by and rotatable with the workpiece support structure. Thus, the prior apparatus, by transferring the rolling loads to the pilot surfaces and thence to the heavy machine base permitted the use of a single die to effect the rolling operation.

It is recognized that the accuracy with which the workpiece is formed is dependent on the rigidity with which the workpiece is supported during the rolling operation. Experience has shown that it is wholly impractical to provide a rotatable workpiece support having sufficient resistance to deflection and having sufficient precision to assure positioning of the workpiece throughout the forming operation with the required accuracy.

While the apparatus of application Ser. No. 817,669 eliminates the need for a second forming die to absorb the rolling loads it continues to rely on the workpiece support to locate the workpiece positively in two planes i.e. in a plane normal to the planes containing the axes of the forming roll and the workpiece and in a plane normal to these axes. Accordingly the prior apparatus retains the requirement for a relatively massive, high precision work support assembly.

SUMMARY OF THE INVENTION It is the principal purpose and object of the present invention to provide improved apparatus for roll forming toothed workpieces, such as gears, which efiects an important simplification in prior apparatus and a corresponding reduction in cost while effecting the production of finished parts having an accuracy equal to or better than the best prior available apparatus.

In obtaining this and other objects the present invention provides gear forming apparatus in which the workpieces are formed to final configuration by rotating them in high-pressure engagement with a single forming die carried by a driven arbor. Typically, the workpiece is centrally apertured and is carried on a support assembly comprising a pair of axially aligned support members, one of which engages the workpiece aperture. The support members preferably are each provided with a cylindrical pilot surface concentric with the workpiece axis and disposed closely adjacent to a side surface of the workpiece. Each of the pilot surfaces runs in rolling contact with a pair of cylindrical backup members rotatably mounted on the machine structure which carries the forming die.

In operation the backup members absorb the full rolling load. The axes of the backup members are offset equally from the plane containing the axes of forming roll and the workpiece. Accordingly the backup members also absorb any force developed during the rolling operation which tends to move the axis of the workpiece out of the plane containing the axis of the roll and the axis of the workpiece.

Thus the workpiece support assembly is required to absorb only the relatively minor forces developed during rolling which tend to move the workpiece along its axis. The absorption of these forces is accomplished by a two part support assembly, each part having a surface engageable with a side surface of the workpiece. Each support part is moveable axially of the workpiece, one part being axially moveable to a predetermined position to positively locate the workpiece, the other part clamping the workpiece in its located position.

As a further feature of the invention, the forming roll, workpiece support assembly, and backup members are so arranged as to provide automatic gauging of the size of the workpiece inserted into the apparatus. This arrangement automatically prevents the insertion of a workpiece which is sufficiently oversize to damage the apparatus.

Additional objects, features and advantages of the invention will become apparent as the description proceeds.

DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view of a gear finishing apparatus constructed in accordance with the present invention;

FIG. 2 is an enlarged front view of the apparatus shown in FIG. 1;

FIG. 3 is a transverse section taken along line 33 of FIG. 2 showing details of the workpiece support apparatus; and

FlG. 4 is a vertical section taken along line 4-4 of FIG. 2 showing further details of construction.

DESCRIPTION OF PREFERRED EMBODIMENT The rolling apparatus of the present invention comprises a base structure indicated generally at 20 by which a head assembly 22 is supported upon an upwardly projecting rigid column 24. To impart further rigidity to the assembly the head section 22 is connected to an opposing head section 21 by a pair of

tie bars

26 and 28. An upper spindle assembly, indicated generally at 30, is rotatably supported in a trunnion assembly 32 carried by a column 34 projecting downwardly from the head section 22. The spindle assembly is driven by any convenient means for example a hydraulic motor 36. Convenn'onal mechanisms are included in the trunnion assembly 32 and the column 34 to permit all of the required adjustments, the axis of the upper spindle assembly 30 is fixed. A die 38 preferably of the type disclosed in application Ser. No. 809,365 is rigidly secured to the upper spindle for rotation therewith about an axis concentric with the axis of the spindle assembly.

The workpiece W is carried by a support assembly, illustrated in detail in FIG. 3, comprising a pair of

identical arbors

40 and 42 and a pair of

fittings

44 and 46. The

arbors

40 and 42 are mounted for axial movement and for rotation in

housings

47 and 48, respectively, carried by a frame structure 49 supported for vertical movement on a pair of

vertical shafts

50 and 52 carried in suitable fittings rigid with the rear machine column 24. The frame assembly 49 is biased upwardly by a spring 54 mounted centrally of the frame assembly.

The arbor assembly 40 is mounted in precision bearings 56 for rotation and axial sliding movement within the housing 47 and at its inner end is connected through a series of thrust bearings 58 to a fitting 60 on the end of a piston rod 62 projecting from a hydraulic motor 64 carried by the housing 47. The arbor 42 is similarly mounted in the housing 48 and similarly connected to the piston of a somewhat smaller opposed hydraulic motor 66. Each of the

arbors

40 and 42 carry a spring loaded centering pin such as that shown at 67.

The fitting 44 has a flat end face 68 adapted to engage the flat end face of the arbor 40 and a central recess 70 for engagernent by the centering pin 67. The fitting has an opposed radial surface 72 adapted to engage the side surface of the workpiece W. A cylindrical section 74 on the fitting 44 projects through central aperture 76 of the workpiece in close clearance relation thereto and into a cylindrical recess 78 in the fitting 46. A reduced end portion 80 of the cylindrical projection 74 is provided with a central recess 82 to receive the centering pin associated with the arbor 42. Accordingly, the workpiece is initially positively located with respect to the

fittings

44 and 46 which as a unit, are positively initially located by the

arbors

40 and 42. The motor 66 is either smaller than the motor 64 or is supplied with fluid under reduced pressure. Accordingly, when the

arbors

40 and 42 are advanced, the arbor 40 reaches the limit position determined by a stop, not shown, which may be located internally of the motor 64. The arbor 42 is not permitted to reach a stop so it constantly urges the fitting 46 against the side face of the workpiece to urge the opposite side face against the locating surface 72 on the fitting 44. This arrangement assures the proper location of the workpiece along its own axis. The

arbors

40 and 42, however, are totally inadequate to absorb, with acceptable deflection, the loads imposed on the workpiece during the rolling operation.

The unique apparatus provided to absorb these loads includes the

fittings

44 and 46 and associated pairs of

backup members

84, 86 and 88, 90. The

backup members

84 and 88 are preferably carried by a common shaft 92 and the backup members 86'and 90 are similarly carried by a common shaft 94. The

shafts

92 and 94 are mounted in upwardly projecting

arms

96 and 98 carried by a frame assembly 100 supported on

slideways

102 and 104 for movement in a directional normal to the plane containing the axis of the die 38 and the workpiece W. Slideways I02 and 104 are formed on the head assembly 106 of a conventional hydraulic ram, not shown, mounted to the lower machine head 21. As explained below, the ram is effective to raise the workpiece into rolling engagement with the die 38 and subsequently lower the workpiece after the rolling operation has been completed.

The frame assembly 100 carrying the backup members 84-90 is moved between the full line operating position shown in FIG. 4 and the dotted line loading position by a toggle mechanism 108. When the toggle mechanism is operated by movement of the handle 110 in a clockwise direction as viewed in FIG. 4, a rod 112 attached to the toggle mechanism and the frame assembly 100 withdraws the latter to the right.

When the machine is at rest, the

arbors

40 and 42 are separated and the arbors and backup members are lowered. The machine may be readied for loading by manipulating the toggle mechanism 108 to withdraw the backup rollers and associated structure to the dotted line position FIG. 4. The workpiece and the fitting 46 are successively assembled on the fitting 44. This subassembly is then positioned in place on the backup rollers 84-90 to dispose the cylindrical surface 1 14 of the fitting 44 in engagement with the corresponding cylindrical surfaces of the

backup members

88 and 90 and the cylindrical surface 116 on the fitting 46 in contact with the corresponding cylindrical surfaces of the

backup members

84 and 86.

The toggle mechanism 108 is then manipulated to move the parts to the full line position of FIG. 4. Suitable adjustable stops areprovided to dispose the axes of the backup rollers in the proper relationship to a plane containing the axis of the die 38 and the workpiece W. It is a feature of the invention that the distance between the

shafts

92 and 94 and the axis of the die 38 is such that when the hydraulic ram is lowered a properly sized workpiece can be easily moved into position but an oversized workpiece will be blocked thus preventing the inadvertant loading of an oversized workpiece which might cause breakage of the die.

With the workpiece in proper position the

arbors

40 and 42 are advanced toward each other and the ends of the locating pins 67 enter the recesses provided in the

fittings

44 and 46. As explained above the advancement of the arbor 40 continues until it abuts against a positive stop and the arbor 42 tightly clamps the workpiece in its proper axial position.

After the workpiece has been thus located the rolling operation is initiated manually and thereafter performed automatically. When the operator depresses a suitable start button a two piece sheet metal shield assembly 118 is automatically raised to cover the front of the machine. The motor 36 is then operated to drive the die 38 which is in rolling engagement with the workpiece W. In accordance with the conventional practice coolant is supplied throughout the rolling operation. The main hydraulic ram is then energized to raise the head 100 together with the backup members 84-90 which in turn act on the

fittings

44 and 46 to raise the workpiece, the

arbors

40 and 42 and the associated frame structure 49 to bring the workpiece into pressure engagement with the die. The upward movement of the parts is automatically arrested, the die and the workpiece are rotated through a suitable dwell period and the parts are then lowered. The operation of the drive motor 36 is discontinued and the shield assembly 1 i8 is lowered. The

arbors

40 and 42 may then be axially separated to allow removal of the finished workpiece by manipulation of the toggle mechanism.

Because of the force transmission path from the backup members 84 and through the fittings to the workpiece W, the

arbors

40 and 42 and associated mechanisms are freed from any substantial radial loads and the workpiece runs in substantially exact coneentricity with its own axis. Further because of the location of the pilot surfaces 114 and 116 of the

fittings

44 and 46, respectively, immediately adjacent to the side faces of the workpiece, bending moments are reduced to a minimum and deflections in this system approach their minimum theoretical value. To impart further rigidity to the system and to reduce the number of parts that must be manufactured to very close tolerances, the pairs of

backup members

84 and 88 and 86 and 90 and their associated

shafts

92 and 94, respectively, may be formed integrally.

We claim:

1. Apparatus for roll forming a toothed workpiece comprising a toothed forming roll mounted for rotation about a predetermined axis, a workpiece support assembly adapted to support a workpiece for rotation about an axis essentially parallel to said predetermined axis and in rolling engagement with said forming roll, said support assembly comprising a pair of support members, means for moving one of said workpiece support members to a predetermined locating position, means to move the other member into clamping relation with said workpiece to hold said workpiece against said one support member at said locating position, thereby restraining said workpiece against movement along its axis, said support assembly having first and second cylindrical pilot surfaces concentric with the rotational axis thereof, said first and second pilot surfaces being disposed, respectively, at opposite sides of said workpiece, and means providing first and second pairs of cylindrical backup surfaces, each pair being adapted to run in rolling contact with one of said pilot surfaces.

2. The apparatus according to claim 1, wherein said workpiece is centrally apertured and wherein one of said support members extends through said central aperture and each of said support members has a radial surface adapted to engage the side radial surfaces of said workpiece.

3. The apparatus according to claim 1, wherein said backup surfaces are mounted for movement laterally of a plane con- 3 6 3 l 7 O4 5 6 taining the axis of said forming roll and the axis of said workpiece support assembly between a rolling position and a loading position, the spacing between said forming roll and said backup surfaces being such as to prevent the movement of an oversized -workpiece to said rolling position. 5

Claims

3. The apparatus according to claim 1, wherein said backup surfaces are mounted for movement laterally of a plane containing the axis of said forming roll and the axis of said workpiece support assembly between a rolling position and a loading position, the spacing between said forming roll and said backup surfaces being such as to prevent the movement of an oversized workpiece to said rolling position.