US3583190A

US3583190A - Chipless production of tapered gears having spirally arranged teeth

Info

Publication number: US3583190A
Application number: US784350A
Authority: US
Inventors: Ernest Wildhaber
Original assignee: Gleason Works
Current assignee: Gleason Works
Priority date: 1968-12-17
Filing date: 1968-12-17
Publication date: 1971-06-08
Anticipated expiration: 1988-06-08
Also published as: GB1280720A; DE1961762A1; JPS4947621B1; FR2026372A1

Abstract

The chipless production of tapered or bevel gears having spirally arranged teeth, by either forging or rolling, where a die member and a prospective gear are relatively approached in the direction of the axis of one of said members. There is a relative approach in the direction of the axis of the tapered gear accompanied by a relative turning motion between the gear and the die member and about said axis. The relative approach is essentially a helical motion of the same hand as the hand of the spirally arranged teeth.

Description

United States Patent Inventor Ernest Wildhaber Rochester, N.Y.

Appl. No. 784,350

Filed Dec. 17, 1968 Patented June 8, 1971 Assignee The Gleason Works Rochester, N.Y.

CHIPLESS PRODUCTION OF TAPERED GEARS HAVING SPIRALLY ARRANGED TEETH 8 Claims, 11 Drawing Figs.

U.S. Cl 72/84, 72/102, 29/1592 Int. Cl B2lh 5/04, B21k 1/30 Field of Search 72/80, 82, 84, 86, 87, 94, 406, 418; 29/1592; 72/102 References Cited UNITED STATES PATENTS 1,240,914 9/19 I 7 Anderson 72/84 1,850,395 3/1932 Hughes 29/159.01 2,883,894 4/1959 Tsuchikawa 72/105 FOREIGN PATENTS 885,103 12/1961 Great Britain 29/1592 Primary Examiner Lowell A. Larson Attorneys-Cushman, Darby & Cushman and Morton A.

Polster ABSTRACT: The chipless production of tapered or bevel gears having spirally arranged teeth, by either forging or rolling, where a die member and a prospective gear are relatively approached in the direction of the axis of one of said members. There is a relative approach in the direction of the axis of the tapered gear accompanied by a relative turning motion between the gear and the die member and about said axis. The relative approach is essentially a helical motion of the same hand as the hand of the spirally arranged teeth.

PATENTED JUN s :97:

SHEET 1 BF 2 FIG.2

FIG.5

I FIG? INVENTOR.

- ERNEST WILDHABER ATTORNEY PATENIED Jun 8137! SHEEI 2 OF 2 INVENTOR.

ERNEST WILDHABER CI-IIFLESE PRODUCTION OF TAIERED GEARS HAVING SPIRALLY ARRANGED TEETH The present invention relates to the production of tapered or bevel gears, and in particular to the production by either forging or rolling techniques, of such gears having spirally arranged teeth.

Tapered gears with spirally arranged teeth have oppositely facing tooth surfaces unequally inclined to an axial viewing direction. Likewise the opposite tooth profiles of any cylindrical section coaxial with the gear are unequally inclined to the direction of the gear axis. An approach between the die member and gear purely in the direction of the gear axis approaches mating tooth sides at different rates, at a slow rate on the longitudinally convex tooth sides of the gear, at a fast rate on the longitudinally concave side. More material is then pushed away on said concave side so that a substantial torque is exerted between die member and gear. Also the forming action is very unequal on opposite sides.

One object of the invention is to reduce said torque and to improve the forming action. A further aim is to make the method applicable also to such cases where a cylindrical section coaxial with the gear shows a negative profile inclination on one side, so that this one side cannot be reached with a purely axial approach. This condition occurs on some hypoid gears with large shaft offset.

Other objects are to provide novel apparatus and structures designed to carry out the method of the invention in either forging or rolling operations.

Another object is to avoid or decrease distortion in the production by rolling.

The foregoing and other objects and advantages of the invention will appear from the following description of the preferred embodiments illustrated in the accompanying drawings, wherein:

FIG. I is a plan view of a bevel gear with some of its spirally arranged teeth illustrated schematically thereon.

FIG. 2 is a side elevational view of the gear shown in FIG. 1.

FIG. 3 is an end elevational view of the gear shown in FIG. 1.

FIG. 4 is an enlarged and fragmentary sectional view taken along the cylindrical section line 15 of FIG. I and developed into a plane, and also showing a tooth of the die member before full depth engagement and being fed axially into the gear.

FIG. 5 is a view corresponding to FIG. 4 and showing the tooth ofthe die member being fed helically into the gear.

FIG. 6 is a view corresponding to FIG. 5 but showing gear teeth with negative profile inclination on one side.

FIG. 7 is a partially sectioned and fragmentary view of a forging press embodying the invention.

FIG. 8 is a diagrammatic view showing a gear in axial section at full depth engagement with a rotary die member, with the instant axis of relative motion in a preferred position adjacent the top of the die teeth;

FIG. 9 is a view corresponding to FIG. 8 but showing the start of the rolling operation.

FIG. 10 is a fragmentary and partially sectioned view of an apparatus embodying the invention and designed for the production of gears in a rolling process.

FIG. 11 is a fragmentary plan view of a ring gear having spirally arranged teeth that are curved lengthwise and which is designed to be produced by the apparatus shown in FIG. 10.

Referring now to the drawings, FIG. 1 is a diagrammatic view ofa gear 8 taken in the direction of its axis 9. Gear 8 has spirally arranged teeth 10 which are shown as being curved lengthwise. They are indicated with their pitch lines only. Normal 11 in FIGS. 1, 2 and 3 is the tooth surface normal at mean point P of the tooth side facing outwardly. This is the side that is convex lengthwise. Normal 11 is inclined to a pitch plane 12 tangent to the pitch surface of gear 8 at an angle referred to as the pressure angle. It is inclined at a much smaller angle to a plane 13 (FIG. 3) perpendicular to the gear axis 9. In FIG. 3 this angle appears as an angle 14. This is also the profile inclination of a cylindrical section 15 (FIG. 1) coaxial with gear axis 9. It is the inclination to the axial direction of profile I6 of FIGS. 4 and 5. The inclination of opposite profile I7 is much larger.

The inclination difference is further increased on hypoid gears. While spiral bevel gears have intersecting axes and about equal pressure angles on both sides of the teeth with respect to pitch plane 12, hypoid ring gears generally have a lower pressure angle on the longitudinally convex side of the teeth than on the concave side. In some cases this may result in a negative inclination of profile 16' of the longitudinally convex tooth side, (FIG. 6).

The inclination difference of opposite tooth sides of spirally arranged teeth is also apparent in the axial view of the gear 18 shown in FIG. 11. The longitudinally convex tooth sides 20 are barely visible, while the concave tooth sides 21 appear wide.

The purely axial approach between die member 19 and gear 8, (FIG. 4), pushes away far more material adjacent side 17 than adjacent side I6. More pressure is exerted on side 17. This results in a substantial torque load on both members and in unequal flow of material on opposite tooth sides. An inclined approach direction 9, in accordance with the invention, improves the flow and reduces or even eliminates the torque. This direction is attained with a helical approach. The relative approach is along and about axis 9 of the work member 8.

FIG. 6 shows how such an approach extends the range of the process to include gears with negative inclination of profile 16', (FIG. 6).

Diagram FIG. 7 outlines a forging press operating with helical approach. Die member 19 is moved along and about its axis, that coincides with axis 9 of the work member or prospective gear 8. Stationary hydraulic cylinder 25 extends about axis 9. Its piston 26 and ram 27 are constrained to move in a helical path by a helical gear 28 rigidly secured thereto and engaging a counterpart stationary internal helical gear 30. Other forms of a helical constraint could be substituted if desired.

The die member 19 is secured to the front of gear 28. It contains an internally tapered face surface and teeth that are the counterpart of the tooth spaces of the finished gear 8. A central portion 31 is secured to member 19, to form the inner ends of the gear teeth and the top 32 of the gear flange.

The outer tooth ends and the back of gear 8 are formed by a part 33 coaxial with axis 9 and containing a hub 34. The bore or central opening is formed by a rod 35 placed inside of hub 34 and reaching into a preformed hole. Part 33 rests on base 36. Both part 33 and rod 35 are maintained stationary during forging. For ejection of the gear, after completion, part 33 is advanced axially, while rod 35 is kept stationary.

Strong ties 38 connect the base 36 with the upper end of cylinder 25.

It might be thought that a helical relative approach could also be attained without constraint by a turning motion of the work member while the die member has a purely axial approach, and that the work member would slide about its axis when the torque exerted thereon becomes too large. However the large axial pressure and high coefficient of friction would require a very large torque for such slippage.

A constrained helical approach according to the invention not only can keep the torque low, but it securely holds the work member. This is particularly important when forging is done with several strokes.

PRODUCTION BY ROLLING FIG. 8 shows a work member or gear 40 in full-depth engagement with a rotary die member or tool gear 41. Their

axes

42, 43 intersect at apex 44. The die member may be a gear of large face angle and sometimes a crown gear.

I preferably choose the tooth ratio and the angle between the

axes

42, 43 so that the instant axis 45 of relative motion extends along the face of the die member or nearly so. Such determination can be attained with the known procedures of the gear art. The instant axis 45 of relative motion is close to the face surface of said die member and has a spacing from said face surface of between zero and one-fourth of its tooth depth all along the length of the teeth.

In other words the tooth ratio and angles are so selected that the face surface of the die member rolls on the root surface of the gear at full-depth position, FIG. 8. This gives rolling contact at the tooth bottom where the maximum pressure is, and it minimizes sideswiping in this critical region.

At the outset, before teeth are formed, the face of the smooth blank extends along dotted line 46 well inside of the final face profile 46. FIG. 9 shows the beginning of the rolling operation. While in known practice the relative approach is along axis 43 of the die member, or more broadly in a direction approximately at right angles to the pitch surface of gear 40, the invention uses an approach in the direction of the axis 42 of tapered gear 40. The instant axis 45 then remains fixed with respect to the die member and keeps extending along its tooth tops. Thus the die member starts engagement at rolling motion without slippage. lt plunges straight into the blank.

FIG. 10 shows work member or gear 18 in the final position of engagement with rotary die member 50. Work member 18 is secured to a cup part 51 that is rotatably mounted on head 52 of plunger 53. It is journaled thereon by roller thrust bearing 54 and bearing 55. Plunger 53 is hydraulically operated to move in the direction ofthe gear axis 56.

Cup part 51 has helical spline 57 formed on its outside. They engage counterpart helical splines provided inside of the hub 58 of a timing gear 60. Timing gear 60 is mounted on stationary portion 61 by

bearings

62, 63. It meshes with a timing gear 64 secured to the head 65 of the die spindle with axis 66. The die member 50 is secured to head 65.

The flange containing timing gear 60 is provided with teeth 68 on its outside. Driving power is applied to them.

In operation the rotating work member 18 approaches the rotating die member 50 in the direction of and angularly about its axis 56, as constrained by the helical splines or guides 57. These are of the same hand as the hand of the spirally arranged teeth of gear 18, right hand on the right-hand gear shown, left hand on a left-hand gear.

The process is not confined to rolling without previous indentation. It may also be used for finishing after teeth have already been formed.

What I claim is:

l. The method of producing tapered gears having spirally arranged teeth, which comprises relatively approaching a die member to a prospective gear (a) in the direction of the axis of said gear and (b) also angularly about said axis to an end position where the resulting shape is applied, the direction of said approach being the same as the hand of the spirally arranged teeth of said gear, and being right hand on a right-hand gear and left hand on a left-hand gear.

2. The method of producing tapered gears according to claim 1, wherein a forging die is relatively approached to a prospective gear in a constrained helical motion about the axis of said gear.

3. The method of producing tapered gears according to claim 1, wherein a toothed die member and a prospective gear are rotated in timed relation on their respective axis while a relative approach is effected between them in the direction of and angularly about the axis of said gear.

4. The method of producing tapered gears having spirally arranged teeth, which comprises rotating a toothed die member and a prospective gear on intersecting axes in timed relation so that the instant axis of relative motion is close to the face surface of said die member and has a distance from said face surface between zero and one-fourth of its tooth depth all along the length of its teeth, and effecting relative approach between said die member and gear (a) in the direction of and (b) angularly about the axis of said gear to an end position where the entire resulting tooth shape is applied, the hand of said approach being the same as the hand of said ear 5. The method according to claim 4, wherein t e instant axis extends in the direction of the profile of the face surface of said die member in an axial section thereof.

6. The method according to claim 4, wherein the prospective gear is helically approached about its axis to the die member.

7. In a forging machine, a die having an internally tapered annular face surface and spirally arranged teeth following said face surface, said die being secured to a plunger movable along the axis of said face surface, and positive means for constraining said plunger to turn about said axis as it moves along it.

8. In a rolling apparatus, a die member having spirally arranged teeth disposed along a circle, and a workpiece, means mounting said die member and said workpiece for rotation about intersecting axes, and means for effecting relative feeding motion between said die member and said workpiece simultaneously along and around the axis of said workpiece.

Claims

1. The method of producing tapered gears having spirally arranged teeth, which comprises relatively approaching a die member to a prospective gear (a) in the direction of the axis of said gear and (b) also angularly about said axis to an end position where the resulting shapE is applied, the direction of said approach being the same as the hand of the spirally arranged teeth of said gear, and being right hand on a right-hand gear and left hand on a left-hand gear.

4. The method of producing tapered gears having spirally arranged teeth, which comprises rotating a toothed die member and a prospective gear on intersecting axes in timed relation so that the instant axis of relative motion is close to the face surface of said die member and has a distance from said face surface between zero and one-fourth of its tooth depth all along the length of its teeth, and effecting relative approach between said die member and gear (a) in the direction of and (b) angularly about the axis of said gear to an end position where the entire resulting tooth shape is applied, the hand of said approach being the same as the hand of said gear.

5. The method according to claim 4, wherein the instant axis extends in the direction of the profile of the face surface of said die member in an axial section thereof.