US3845944A

US3845944A - Adjustable expanding die

Info

Publication number: US3845944A
Application number: US00304215A
Authority: US
Inventors: R Miller; E Murin
Original assignee: Mack Trucks Inc
Current assignee: Mack Trucks Inc
Priority date: 1972-11-06
Filing date: 1972-11-06
Publication date: 1974-11-05
Anticipated expiration: 1991-11-05

Abstract

An adjustable expanding die for engaging a bore in an object held between a pair of opposed clamping members comprises a unitary outer annular member and a variable diameter inner annular member, which includes a plurality of radially movable arcuate segments. A spring member couples each arcuate segment to the outer annular member and biases the segment radially inwardly. A plug may be inserted axially into the inner annular member to engage the arcuate segments. Each arcuate segment includes an axial projection that has a bore-engaging exterior surface and an interior surface adapted to cooperate with the surface of the plug such that moving the plug axially into the inner annular member expands the member to a desired outer diameter. The plug is threadedly mounted on one clamping member and may be selectively rotated to vary its axial position relative to the clamping member, thereby selectively adjusting the amount by which the inner annular member may be expanded.

Description

llnited States Patent I 1 91. Miller et al. I

[ NOV. 5, 1974 ADJUSTABLE EXPANDING me 57 ABSTRACT [75] Inventors: Robert T. Miller; Elias M. Murin, An adjustable expanding die for engaging a bore in an both of l-lagerstown, Md. object held between a air of 0p osed clampin memb p p l b g d ers compnses a umtary outer annu ar mem er an a [73] Asslgnee' Mack Trucks Allentown variable diameter inner annular member, which in- [22] Filed: Nov. 6, 1972 cludes a plurality of radially movable arcuate segments. A spring member couples each arcuate seg- [211 Appl' 304215 ment to the outer annular member and biases the segment radially inwardly. A plug may be inserted axially ggg'gfigg i into the innerannular member to engage the arcuute [581 Fieid 48 1 2 50 segments. Each arcuate segment includesan axial pro- 269 I51 L 2 i 5 1 jection that has a bore-engaging exterior surface and 1 an interior surface adapted to cooperate with the sur- [56] References Cit d face of the plug such that moving the plug axially into UNITED STATES PATENTS the inner annular member expands the member to a l 359 992 "920 Hook 279/2 desired outer diameter. The plug is threadedly 267l371 3/1954 g /52 X mounted on one clamping member and may be selec- 2,9141311 11 1959 Yarne 1:111:11 266 6 R tWei) rotated to Vary its axial Position relaive the 3,542,333 11/1970 Fade), clamping member, thereby selectively adjusting the 3,709,546 1/1973 Vaughan 279/2 x amount y which the n er annular member may be Primary Examiner-Roy Lake I expanded Assistant Examiner-Mark S. Bicks 9 Claims, 3 Drawing Figures Attorney, Agent, or Firm-Brumbaugh, Graves, Donohue & Raymond I::D l5 I i l ,1 1s 58 5b 2 ii 161 a 1 I7 ..12 5 52 b4 "1 m 3 1 a L, ,-fi I l 4.2 ,////.'/Y 4LY I9 13 U4 3 3636 7 1 W5 41 ,1!

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l ADJUSTABLE EXPANDING DIE BACKGROUND OF THE INVENTION One step in the productionof precision gears involves quenching or cooling the gears after they have been heat-treated. A hot gear is immersed in a bath of oil or other liquid while it is held in a die to prevent distortion during the cooling process. The quenching operation is commonly carried out in a quenching press in which a hydraulically operated ram engages the upper horizontal surfaces of a gear lying on a stationary die assembly. A die is provided to engage the bore of the gear to maintain the required diameter.

An accepted practice in die quenching gears is to assemble a heated gear on a solid bore-engaging plug mounted in a quenching press, close the press, and then quench the gear in oil. During quenching, the bore of the gear closes on the plug, 50 that after the quenching operation both the gear and the plug must be placed on a power press to press the plug out of the bore. If bore diameters of the heated gears are within close tolerances, only a single size quench plug is necessary to produce acceptable finished gears. In large scale production, however, it is difficult to adequately control the bore diameters. The metallurgical properties of steel will vary significantly from heat to heat. In addition, several broaches or reamers may be used for each bore diameter to maintain availability to production. Normal wear and regrinding creates size variations between individual tools, all within tolerance. Together, the metallurgical and broaching variations create a need for bore size adjustments for each lot of gears. Thus, an assortment of various size quench plugs is necessary to produce acceptacle gears.

One'step in the above practice can be eliminated by using an expandable die to maintain the bore diameters of the gears. With an expandable die, a plug associated with the ram of the quenching press engages an annular die member comprised of a plurality of radially movable arcuate segments and forces the arcuate segments radially outwardly to engage the bore of a gear. The expandable die makes it unnecessary to press out the plug because the plug is pulled out of the arcuate segments when the ram of the quenching press is raised. Spring members then drive the arcuate segments radially inwardly away from the bore.

Typical expanding dies are shown in the Rossbach US. Pat. No. 3,334,882 and the Yarne US. Pat. No. 2,914,3l l. The plug of the Rossbach die is designed to accommodate a gear with a stepped bore. The Yarne die has a plug that is hydraulically movable independently of the quenching press ram, so that the ram and the plug can exert different degrees of pressure to compensate for any variations in the behavior of the gear metal during quenching. Neither of the above dies, however, eliminates the need for an assortment of plugs to accommodate variations in the bore diameters of heated gears. In order to adjust the final expanded diameter of the die, the plug must be exchanged for one of a different size.

SUMMARY OF THE INVENTION The present invention provides a novel expanding die which can be quickly and easily adjusted to accommodate variations in the bore diameters of heated gears. The die comprises a unitary outer annular member, and

a variable diameter inner annular member which includes a plurality of radially movable arcuate segments. Spring members couple each arcuate segment to the outer annular member and bias the segments radially inwardly. A cone-shaped plug may be inserted axially into the inner annular member to engage the arcuate segments.

Each arcuate segment has an axial projection with a cylindrical bore-engaging exterior surface. The segments also have interior surfaces adapted to cooperate with the plug such that moving the plug axially into the inner annular member effects an increase in an outer diameter of the member. Specifically, moving the plug into the inner annular member forces the arcuate segments radially outwardly so that the exterior surfaces of the segment projections engage the wall of a gear bore, whether the bore wall is smooth or splined.

The plug is threadedly mounted on a movable clamping member, such as the ram of a hydraulic quenching press, for selective and rotational variation of itsaxial position relative to the clamping member, thereby selectively to adjust the increase in the outer diameter of the inner annular member.

In operation, a heated gear is assembled on the inner annular member of the expanding die, which together with the outer annular member forms a part of a stationary die assembly in a quenching press. As the quenching press ram, carrying the plug, is lowered to engage the upper horizontal surfaces of the gear, the

. plug simultaneously forces the arcuate segments of the inner annular member outwardly to a particular diameter. If the expanded diameter of the die proves to be too large or too small, the ram is raised and the plug is screwed either into or out of the ram to adjust the final expanded diameter of the inner annular member. By careful measurement of the pitch of the threads on the threaded portion of the plug and of the included angle of the taper of the plug, rotation of the plug in the ram can be accurately correlated to change in the expanded diameter of the inner annular member.

As can be seen from the above description, the present invention provides a substantial improvement .over the prior art technique of maintaining an assortment of various size quench plugs. Variations in the bore diameter of heated gears can be more easily and accurately accommodated with the invention than with a plurality of quench plugs. By accurate calibration of the plug, the diameter of the die can be adjusted with much greater accuracy than would be feasible with a variety of quench plugs, thereby providing more accurate control of the size of the bore of the gear being quenched. In addition, the threaded adjustment of the plug is less expensive and less subject to mechanical failure than a hydraulic adjustment would be. In particular, the threaded adjustment avoids inaccuracies resulting from pressure variations that are often found with plugs set by fluid pressure.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference may be made to the following description of an exemplary embodiment taken in conjunction with the figures of the accompanying drawings, in which:

FIG. 1 is a sectional side view of an adjustable expanding die according to the invention, together with portions of a conventional quenching press;

FIG. 2 is an enlarged view of the die of FIG. 1, taken along the line 2-2 of FIG. I and looking in the direction of the arrows, a portion of the plug being broken away for clarity; and

FIG. 3 is a view of the upper clamping member, taken along the line 33 of FIG. 1 and looking in the direction of the arrows.

DESCRIPTION OF A PREFERRED EMBODIMENT In the illustrative embodiment of the invention shown in FIGS. 1-3, an adjustable expanding die is used to engage the bore 11 of a gear 12 (shown in phantom). The gear 12 is assembled on the expanding die 10 which, together with a lower die or clamping member 13 (shown in phantom) of a conventional Gleason quenching press, for example, forms a stationary die or clamping assembly. An upper die or clamping member 14, which is threadedly mounted on a hydraulically operated actuating piston 15 (shown in phantom) of the quenching press, may be reciprocated axially of the gear 12, and when driven downwardly (as viewed in FIG. 1) engages the upper lateral surface of the hub 16 of the gear 12. An outer ring shaped member (not shown) also actuated by the quenching press engages the upper lateral surface of the teeth 17 of the gear 12. As can be seen in FIGS. 1 and 3, the lower surface of the upper clamping member 14 is provided with a plurality of radial grooves 18 and the upper surface of the lower clamping member 13 is provided with a plurality of spaced, parallel grooves 19 to permit the free flow of quenching oil around the gear 12.

The expanding die comprises a unitary outer ring 20 and a variable diameter inner ring 21, which includes six radially movable, arcuate segments 22. Both the outer ring 20 and the base portions 23 of the arcuate segments 22 are received in a recess 24 formed in the lower clamping member 13. The recess 24 not only maintains the outer ring 20 in a fixed lateral position, but also permits the teeth 17 of the gear 12 to be properly supported on the lower clamping member 13, as shown in FIG. 1. The outer ring 20 is secured against upward movement by two bolts 26 that pass through bolt holes 28 in the ring 20 and are screwed into the lower clamping member 13.

Each arcuate segment 22 is coupled to the outer ring 20 by a pin 30. One end of each pin 30 is screwed into a corresponding one of six threaded bores 32 that extend radially through the ring 20 from its inner circumference to its outer circumference. Six bores 34 formed in the base portions 23 of the arcuate segments 22 slidingly receive the other ends of the pins 30. Adequate clearance is provided in the inner ends of the bores 34 to permit outward radial movement of the segments 22.

I At their adjacent ends, each pair of

bores

32 and 34 has a pair of

counterbores

36 and 38, respectively, which receive and retain the opposite ends of a spring 40 that is coiled about the corresponding pin 30. The springs 40 bias the arcuate segments 22 radially inwardly and are compressed when the segments 22 move radially outwardly.

Each of the arcuate segments 22 has an axial projection 42 at its inner portion, thereby defining a step 44, which receives and supports a portion of the lower lateral surface of the hub 16 of the gear 12. As shown in FIG. 2, an arcuate groove 46 and tow radial grooves 48 in each step 44 permit the free flow of quenching oil around the hub 16 of the gear 12. The exterior surface 50 of each projection 42 is generally vertical and coaxial and is adapted'to engage the wall of the bore 11 in the gear 12, the exterior surface 50 being machined to the segment of a cylindrical surface having a diameter corresponding to the gear bore surface whose shrinkage is to be restrained during the quenching process. The interior surface 52 of the projection 42 and the base portion 23 of each arcuate segment 22 is machined to a segment of a conical surface to receive a cooperating conical plug 54.

The plug 54 has a cylindrical threaded extension 56 projecting axially from its base, the extension 56 threadedly engaging a threaded bore 58 in the upper clamping member 14. When the actuating piston 15 of the quenching press drives the upper clamping member 14 down on the gear 12, the plug 54 is inserted into the inner annular member 21 formed by the arcuate segments 22 and engages the interior surfaces 52 of the segments 22. The arcuate segments 22 are forced radially outwardly and an increase is effected in the diameter of the segmented cylindrical surfaces 50 of the projections 42, these surfaces 50 constituting the boreengaging surface of the inner annular member 21.

The increase in the diameter of the bore-engaging surfaces 50 of the inner annular member 21 is determined by the extent to which the plug 54 is inserted into the annular member before its travel is halted by the engagement of the upper clamping member 14 with the hub 16 of the gear 12. The increase in diameter may be adjusted, therefore, by varying the axial position of the plug 54 relative to the upper clamping member 14. This can be done by rotating the plug 54 so that it is screwed into or out of the threaded bore 58 in the upper clamping member 14.

To facilitate the adjustment of the axial position of the plug 54 relative to the upper clamping member 14, the tip 60 of the plug 54 is provided with two intersecting slots 62 which accommodate a screwdriver or similar tool for rotating the plug 54. Furthermore, by careful measurement of the included angle of the taper of the plug 54 and of the pitch of the threads in the extension 56, each full revolution of the plug 54 can be translated into an incremental change in the diameter of the bore engaging surfaces 50. For example, if the threads on the extension are ground 12 pitch and the included angle of the taper of the plug 54 is 21, each revolution of the plug 54 will result in an incremental change of 0.030 inch in the diameter of the bore-engaging surfaces 50. Scribe lines 64 spaced at 36 intervals around the circumference of the base of the plug 54 make it possible to accurately rotate the plug 54 through onetenth of a revolution to achieve 0.003 inch of incremental change in the bore-engaging diameter. Interpolation between the scribe lines permits accurate adjustment within tenths of thousandths of an inch.

In operation, the heated gear 10 is placed on the lower clamping member 13 with the projections 42 of the arcuate segments 22 extending into the bore 11 of the gear 12. The plug 54 on the upper clamping member 14 is then lowered into the inner annular member 21 formed by the arcuate segments 22. The segments 22 are forced radially outwardly to engage the wall of the bore 11. If the bore-engaging surfaces 50 of the arcuate segments 22 do not properly engage the bore 11 of the gear 12, the upper clamping member 14 is raised and the expanded diameter of the bore-engaging surfaces 50 of the inner annular member 21 is effectively adjusted by screwing the plug 54 into or out of the upper clamping member 14, as necessary. When the proper diameter is achieved, the upper clamping member 14 is lowered and the quenching operation is carried out. After the gear 11.2 is quenched, the plug 54 is lifted out of the inner annular member 21 by raising the piston 15, and the springs 40 drive the arcuate segments 22 radially inwardly away from the wall of the bore 11, allowing the gear 12 to be removed easily.

It will be understood that the above described embodiment is merely exemplary and that those skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such modifications and variations are intended to be within the scope of the invention as defined in the appended claims.

We claim:

1. An adjustable expanding die for engaging a bore in an object held between a pair of opposed clamping members, one of the clamping members being adapted for movement toward and away from the other clamping member, comprising a unitary outer annular memher, a variable diameter inner annular member including a plurality of radially movable arcuate segments, spring means for coupling each arcuate segment to the outer annular member and for biasing the arcuate segments radially inwardly, and a plug movable axially into the inner annular member to engage the arcuate segments, each arcuate segment having a bore engaging exterior surface and an interior surface adapted to cooperate with a surface of the plug such that moving the plug axially into the inner annular member into engagement with the arcuate segments effects an increase in an outer diameter of the inner annular member, the plug being adapted threadedly to engage one of the clamping members for selective and rotational adjustment of its axial position relative to that clampig member, thereby selectively to adjust the final outer diameter attained by the inner annular member when movement of the movable clamping member toward the other clamping member and corresponding movement of the pluginto the inner annular member are halted by engagement of both clamping members with the object.

2. An adjustable expanding die according to claim 1, wherein an end of the plug has at least one radial groove therein adapted to receive a tool for rotating the plug and effecting selective adjustment of the axial position of the plug relative to the one clamping member.

3. An adjustable expanding die according to claim 1, wherein the plug has indicia on a surface thereof calibrated to relate rotational movement of the plug to adjustments in the increase in the outer diameter of the inner annular member.

4. An adjustable expanding die according to claim 1, wherein the plug is generally conical in shape, and the cooperating interior surface of each arcuate segment includes a complementary conical surface.

5. An adjustable expanding die according to claim l,v

wherein each arcuate segment has an axial projection, and the bore engaging exterior surface of each arcuate segment is the exterior surface of the axial projection.

6. An adjustable expanding die according to claim 1, wherein the unitary outer annular member is adapted for mounting on theother clamping member, and each arcuate segment is mounted on the unitary outer annular member to permit radial movement with respect thereto.

7. An adjustable expanding die according to claim 1, wherein the clamping members are adapted for use with a quenching press.

8. An adjustable expanding die for engaging a bore in a gear held between a pair of opposed clamping members used with a quenching press, one of the clamping members being reciprocable toward and away from the other clamping member, comprising a unitary outer annular member adapted for mounting on the other clamping member, a variable diameter inner annular member including a plurality of radially movable arcuate segments, the arcuate segments being mounted on the unitary outer annular member to permit radial movement with respect thereto, each arcuate segment having a bore engaging exterior surface, spring means for biasing each arcuate segment radially in-' wardly, and a plug adapted for mounting on the one clamping member reciprocable into and away from the inner annular member, the plug having a conical surface and the arcuate segments having interior complementary conical surfaces such that moving the plug axially into the inner annular member drives the arcuate segments radially outwardly to engage the bore of the gear, the plug being adapted threadedly to engage the one clamping member to permit adjustment of the axial position of the plug relative to the one clamping member, thereby selectivelyto adjust the final outer diameter attained by the inner annular member when movement of the one clamping member toward the other clamping member and corresponding movement of the plug into the inner annular member are halted by engagement of both clamping members with the gear.

9. ln apparatus having a pair of opposed clamping members for holding a gear therebetween, one of the clamping members being adapted for movement toward and away from the other clamping member, the improvement of an adjustable expanding die for engaging a bore in the gear comprising a unitary outer annular member mounted on the other clamping member, a variable diameter inner annular member including a plurality of radially movable arcuate segments adapted to be received in the bore of the gear, the arcuate segments being mounted on the unitary outer annular member to permit radial movement with respect thereto, each arcuate segment having a bore engaging exterior surface, spring means for biasing each arcuate segment radially inwardly, and a plug mounted on the one clamping member reciprocable into and away from the inner annular member, the plug having a conical surface and the arcuate segments having interior complementary conical surfaces such that moving the plug axially into the inner annular member into engagement with the arcuate segments drives the arcuate segments radiallyoutwardly, the plug threadedly engaging the one clamping member to permit adjustment of the axial position of the plug relative to the one clamping member, thereby to adjust the final outer diameter of the inner annular member achieved when movement of the one clamping member toward the other clamping member and toward the gear disposed between the Y,

clamping members and corresponding movement of the plug into the inner annular member are halted by engagement of the one clamping member with the gear. =0: =1:

Claims

1. An adjustable expanding die for engaging a bore in an object held between a pair of opposed clamping members, one of the clamping members being adapted for movement toward and away from the other clamping member, comprising a unitary outer annular member, a variable diameter inner annular member including a plurality of radially movable arcuate segments, spring means for coupling each arcuate segment to the outer annular member and for biasing the arcuate segments radially inwardly, and a plug movable axially into the inner annular member to engage the arcuate segments, each arcuate segment having a bore engaging exterior surface and an interior surface adapted to cooperate with a surface of the plug such that moving the plug axially into the inner annular member into engagement with the arcuate segments effects an increase in an outer diameter of the inner annular member, the plug being adapted threadedly to engage one of the clamping members for selective and rotational adjustment of its axial position relative to that clampig member, thereby selectively to adjust the final outer diameter attained by the inner annular member when movement of the movable clamping member toward the other clamping member and corresponding movement of the plug into the inner annular member are halted by engagement of both clamping members with the object.

5. An adjustable expanding die according to claim 1, wherein each arcuate segment has an axial projection, and the bore engaging exterior surface of each arcuate segment is the exterior surface of the axial projection.

6. An adjustable expanding die according to claim 1, wherein the unitary outer annular member is adapted for mounting on the other clamping member, and each arcuate segment is mounted on the unitary outer annular member to permit radial movement with respect thereto.

8. An adjustable expanding die for engaging a bore in a gear held between a pair of opposed clamping members used with a quenching press, one of the clamping members being reciprocable toward and away from the other clamping member, comprising a unitary outer annular member adapted for mounting on the other clamping member, a variable diameter inner annular member including a plurality of radially movable arcuate segments, the arcuate segments being mounted on the unitary outer annular member to permit radial movement with respect thereto, each arcuate segment having a bore engaging exterior surface, spring means for biasing each arcuate segment radially inwardly, and a plug adapted for mounting on the one clamping member reciprocable into and away from the inner annular member, the plug having a conical surface and the arcuate segments having interior complementary conical surfaces such that moving the plug axially into the inner annular member drives the arcuate segments radially outwardly to engage the bore of the gear, the plug being adapted threadedly to engage the one clamping member to permit adjustment of the axial position of the plug relative to the one clamping member, thereby selectively to adjust the final outer diameter attained by the inner annular member when movement of the one clamping member toward the other clamping member and corresponding movement of the plug into the inner annular member are halted by engagement of both clamping members with the gear.

9. In apparatus having a pair of opposed clamping members for holding a gear therebetween, one of the clamping members being adapted for movement toward and away from the other clamping member, the improvement of an adjustable expanding die for engaging a bore in the gear comprising a unitary outer annular member mounted on the other clamping member, a variable diameter inner annular member including a plurality of radially movable arcuate segments adapted to be received in the bore of the gear, the arcuate segments being mounted on the unitary outer annular member to permit radial movement with respect thereto, each arcuate segment having a bore engaging exterior surface, spring means for biasing each arcuate segment radially inwardly, and a plug mounted on the one clamping member reciprocable into and away from the inner annular member, the plug having a conical surface and the arcuate segments having interior complementary conical surfaces such that moving the plug axially into the inner annular member into engagement with the arcuate segments drives the arcuate segments radially outwardly, the plug threadedly engaging the one clamping member to permit adjustment of the axial position of the plug relative to the one clamping member, thereby to adjust the final outer diameter of the inner annular member achieved when movement of the one clamping member toward the other clamping member and toward the gear disposed between the clamping members and corresponding movement of the plug into the inner annular member are halted by engagement of the one clamping member with the gear.