US3267812A

US3267812A - Flexible band drive

Info

Publication number: US3267812A
Application number: US384331A
Authority: US
Inventors: Ernst J Hunkeler
Original assignee: Gleason Works
Current assignee: Gleason Works
Priority date: 1964-07-22
Filing date: 1964-07-22
Publication date: 1966-08-23
Anticipated expiration: 1983-08-23
Also published as: CH443828A; FR1441853A; GB1068786A; DE1500399B1

Description

g- 1966 E. J. HUNKELER 3,267,812

FLEXIBLE BAND DRIVE Filed July 22, 1964 5 Sheets-$heet 1 FIG. 2

INVENTOR. ERNST J. HUNKELER AZTTORNEY g 23, 1965 E. J. HUNKELER 3,267,812

FLEXIBLE BAND DRIVE 5 Sheets-Sheet 2 Filed July 22, 1964 g 23, 1965 E. J. HUNKELER FLEXIBLE BAND DRIVE 5 Sheets-$heet 3 Filed July 22, 1964 FIG. 4

FIG.?

FIG.6

r n 3,267,812 Patented Aug 1966 3,267,812 FLEXIBLE BAND DRIVE Ernst J. Hunkeler, Fair-port, N.Y., assignor to The Gleason Works, Rochester, N.Y., a corporation of New York Filed July 22, 1964, Ser. No. 384,331

12 Claims. (Cl. 90-5) The present invention relates to flexible band or tape drives such as are employed in gear generating machines for transmitting motion between a slide and a rotary drum or sector in tangential relation thereto.

The primary objectives of the invention are to increase the load-carrying capacity of such drives without increasing the dimensions of the bands, and to eliminate or at least substantially reduce unwanted oscillations or vibrations in the drive system.

A drive according to the invention comprises a sector supported for angular motion, a member supported for motion tangentially of the sector, flexible bands anchored to said sector and to said member for transmitting motion between them as though they were rolling together in nonslip relation, and means for exerting pressure between said sector and member to effect a friction drive between them supplementary to the positive drive through said bands.

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

FIG. 1 is a drive diagram of a bevel gear generating machine incorporating the improved drive;

FIG. 2 is a detail sectional view taken approximately in plane 22 of FIG. 3;

FIG. 3 is a front view of the drive including the sector, bands and adjacent parts;

FIGS. 4 and 5 are detail sectional views, approximately in planes 4-4 and 55 of FIG. 3; and,

FIGS. 6 and 7 are side and front views of a modified drive.

The drive shown in FIG. 1 is applicable to bevel gear generating machines, such for example as that shown in my co-pending application Serial No. 354,048, filed Mar. 23, 1964. The drive, effected by a unidirectionally rotating motor-driven shaft 1, rocks a tool-carrying cradle 2 back and. forth about its axis 3 and in time therewith rotates a work spindle 4 back and forth about its axis 5. The cradle is supported by a frame 6, FIGS. 25, which also supports a housing in which spindle 4 is journaled. The frame also supports, either directly or indirectly, the other elements of the drive, including shaft 1.

A cam 7 on shaft 1 acts on a follower 8 on a lever 9 to rock the latter about its fulcrum 11 to the frame. A block 12 manually adjustable on the lever, to vary its distance from the fulcrum, is pivoted to a block 13 that is slidable in a transverse guide slot 14 in a slide 15. This slide has bearings 16 slidable on cylindrical rail 17 of a guide 18 supported by the frame.

Flexible steel bands

19 and 21 are anchored by screws 22 to the slide and by band-tensioning devices 23 to a sector 24. This sector is angularly adjustable on the cradle 2, for this purpose being secured thereto by screws 25 anchored in a circular T-slot 26 in the face of the cradle, concentric of axis 3. The sector is so-called because the part of its surface contactable by the bands is confined to the are between anchorages 23. The sector of course may be a complete circular drum if so desired. The band-contacting surface of the sector, designated 27, is cylindrical and coaxial of axis 3; the band-contacting surface 28 of the slide 15 is plane and parallel to guide rail 17. As shown in FIG. 2, the side bands 19, which act to drive the cradle 2 during rotation clockwise in FIGS. 1 and 3, are each approximately half the width of the center band 21 which acts to drive the cradle counterclockwise.

A hearing portion 29 of slide 15 slidably supports a parallel slide 30 that is connected to slide 15 by a lever 31 fulcrumed to the frame at 32. The lever is pivoted to a block 33 that is slidable in a cross-slot 34 in slide 30. A similar block 35, slidable in a cross-slot 36 in slide 15, is pivoted to a block 37 that is adjustable on the lever 31 to vary its distance from fulcrum-32. A re-circulating ball nut 38 non-rotatably secured to slide 30 is threaded onto a screw 39 which constitutes a part of a shaft 41. This shaft is journaled for rotation and constrained against axial motion in the frame, so that upon reciprocation of slide 30 the shaft 41 is rotated back and forth. Shaft 41 drives the work spindle 4 through ratio-of-roll change gears 42, gears 43, differential gear set 44, 45, 46,

bevel gears

47, 48, 49 and 51, and worm and

worm wheel

52 and 53, the latter being on the work spindle. The angle through which the cradle 2 is oscillated during each turn of the cam 7 may be varied by adjustment of block 12 on lever 9, while the ratio of angular motion of the cradle to angular motion of the work spindle 4 may be adjusted coarsely by change of gears 42 and finely by adjustment of block 37 on lever 31.

Indexing of the work spindle, to bring successive tooth slots of a work gear into cutting position, is effected by a mechanism 54 whose output shaft 55 carries the planet gear 45 of differential set 44-46. The mechanism 54, which may be hydraulically operated, is controlled by a valve 56 actuated by a cam 57 on shaft 1. 'By this arrangement indexing occurs once for each turn of shaft 1 and earn 7. The angular position of cam 57 on shaft 1 determines whether such indexing will occur at a reversal point of the rotation of the cradle or during the course of cradle rotation in one direction or the other.

On each side of

bands

19, 21, FIG. 2, the slide 15 has plane surfaces 58 parallel to guide rail 17 and adapted for frictional drive contact with cylindrical surfaces 59 on sector 24. Preferably these

surfaces

58 and 59 are respectively aligned with the neutral or medial planes of the portions of the bands parallel to slide 15 (rail 17) and with the neutral or medial cylinders of the portions of the bands on the cylindrical surface 27. Accordingly these

surfaces

58 and 59 when pressed together constitute frictional drive surfaces which tend to transmit motion between the slide and sector in substantially the same velocity ratio as the motion positively transmitted by the bands.

Pressure for the friction drive is provided by a compression spring 61, FIG. 5, which acts between a pintle 62 supported by a two-part bracket 63 on the machine frame 6 and a plunger 64 which is slidable in a cylinder bore in the bracket and bears against the guide 18. The latter is guidingly supported for motion toward and away from the sector 24 by flanges 65 on bracket 63 and by a pivot 66, FIGS. 3 and 4, secured to the frame 6. This arrangement accommodates manufacturing tolerances in the concentricity of sector 24 and in the bearings of slide 18 and of cradle 2. The pressure exerted by the spring is adjustable by means of a screw 67 disposed between bracket 63 and pintle 62. In a typical machine embodying the invention this pressure is such that the friction drive bears the major portion of the total drive load between the slide and sector, the bands serving primarily to maintain the intended phase relation between these elements. However if desired the pressure may be reduced so that the friction drive will bear only a minor portion of the total drive load, and serve primarily for damping vibrations or oscillations in the hand drive.

Primarily to avoid the possibility of first-and-last tooth spacing error, by causing the band and friction drive to cooperate in as nearly as possible the same manner when cutting every tooth slot of a work gear, means are provided to release the spring pressure between

surfaces

58 and 59 just prior to each tooth slot cutting cycle. These means comprise a cylinder chamber 68, between plunger 64 and bracket 63, to which hydraulic pressure is applied by valve 56 at the same time that this valve causes the index mechanism 54 to operate. Hydraulic pressure may also be applied manually by means of a valve 69, to release the spring pressure between

surfaces

58 and 59 while the machine is being adjusted, particularly when an angular adjustment between the cradle 2 and the sector 24 is being made.

Preferably the

surfaces

58, 59 and the

surfaces

27, 28 are so related that the spacing of the latter is slightly greater than the thickness of the

bands

19, 21, so that slight variations in this thickness will not affect the friction drive between

surfaces

58, 59. If desired, the

surfaces

58, 59 may be omitted so that the friction drive resulting from the pressure of spring 61 (or equivalent pressure means) will be through

surfaces

28, 27 and the bands. In this event it is preferred that there be a slight clearance between

surfaces

27 and 28 and the inner band 21, so that the friction drive will be exclusively through the outer bands 19.

For the purpose of stabilizing the slide 15, a guide 71 is secured to the machine frame 6 beneath the overhanging bearing portion 29 of the slide. A follower 72 on the slide slidably contacts surfaces 73 of this guide, which are parallel to guide rail 17.

The modification illustrated in FIGS. 6 and 7 is useful for transmitting motion between two angularly oscillating members, instead of between an angularly oscillating member and a reciprocating member.

In this modification, two

sectors

74 and 75, which are really complete drums, are mounted for reversing rotation respectively in machine frame 76 and in a guide 77 which is pivoted to the frame at 78. Pressure means, comprising a piston 79 bearing against the guide and a cylinder 81 secured to the frame, act to press

cylindrical surfaces

82 and 83 of the sectors into frictional drive contact when hydraulic pressure is applied to the cylinder through conduit 84.

Flexible steel bands

85 and 86, secured to the sectors by anchorages 87, are arranged to positively transmit angular motion between the sectors in substantially the same velocity ratio as motion transmitted by friction drive through

surfaces

82, 83.

Having now described preferred embodiments of my invention, and their mode of operation and use, what I claim is:

1. A drive comprising a sector angularly movable on a support, a member movable tangentially of the sector on a guide which is movable relative to the support to displace said member toward or away from the sector, flexible bands anchored to said sector and to said member for transmitting motion between them as though they were rolling together in non-slip relation, and means for exerting pressure between the support and the guide to press said member and sector together and thereby effect a friction drive between them supplementary to the positive drive through said bands.

2. A drive according to claim 1 in which said pressure exerting means are arranged to exert said pressure in a direction substantially perpendicular to the plane of tan- .gency of said sector and bands.

3. A drive according to claim 1 in which said sector and member have frictionally engageable surfaces for transmitting motion between them in substantially the same ratio as that transmitted by said bands, said surfaces being maintained in frictional drive contact by said pressure means.

4. A drive according to claim 3 in which the neutral stress portions of said bands are substantially aligned with said frictionally engageable surfaces.

5. A drive according to claim 4 in which there is a pair of such frictionally engageable surfaces on each side of the bands.

6. A drive according to claim 1 in which said member is a slide supported for rectilinear motion on said guide.

7. A drive according to claim 6 in which said guide is pivoted to the support.

8. A drive according to claim 1 in which said member is a sector supported for angular motion in said guide.

9. A gear machine having a frame supporting for angular motion thereon a work spindle and a tool-carrying cradle, a generating train connecting the cradle and spindle for rotation back and forth about their respective axes, actuating means for said generating train, said train having indexing means therein operable by said actuating means for effecting an angular advance of the work Spindle during each cycle of said back and forth rotation, said generating train including a sector secured to the cradle, a slide reciprocable on the frame tangentially of the sector, flexible bands anchored to the sector and to the slide for transmitting motion between them as though they were rolling together in non-slip relation, said slide and member having frictionally engageable surfaces for transmitting motion between them in substantially the same ratio as that transmitted by said bands, pressure means acting between the frame and slide for pressing the slide against the sector to maintain said surfaces in frictional drive contact, and means operable by said actuating means for effecting a release of such pressure during each cycle of said back and forth rotation.

10. A drive comprising a sector supported for angular motion, a member supported for motion tangentially of the sector, flexible bands anchored to said sector and to said member for transmitting motion between them as though they were rolling together in non-slip relation, and means comprising a spring for exerting pressure between said sector and member to effect a friction drive between them supplementary to the positive drive through said bands, and means for releasing said pressure.

11. A gear machine having a drive in the generating train thereof comprising a sector supported for angular motion, a member supported for motion tangentially of the sector, flexible bands anchored to said sector and to said member for transmitting motion between them as though they were rolling together in non-slip relation, and means for exerting pressure between said sector and member to effect a friction drive between them supplementary to the positive drive through said bands; actuating means for oscillating said drive and for intermittently indexing a work gear on the machine in time with such oscillation; and means operable by said actuating means in time with such oscillation for releasing said pressure.

12. A drive comprising a sector supported for angular motion, a member supported for motion tangentially of the sector, flexible bands anchored to said sector and to said member for transmitting motion between them as though they were rolling, together in non-slip relation, and means comprising a fluid pressure device for exerting pressure between said sector and member to effect a friction drive between them supplementary to the positive drive through said bands, and means for releasing said pressure.

References Cited by the Examiner UNITED STATES PATENTS 842,416 1/1907 Nelson 74--95 X 1,160,368 11/1915 Bozell et a1.

(Other references on following page) 5 6 UNITED STATES PATENTS References Cited by the Applicant 12/1925 Stebbins 74--108 X FOREIGN PATENTS 11 1927 Ph 4-209 451940 g i Z4401 150,283 7/1921 Great Britain. 9 1950 Johnson 4 95 X 5 501,097 2/1939 Great Britain. 4/1963 Rieckenberg 74-95 FOREIGN PATENTS 10/1963 France.

9/1935 Italy.

BROUGHTON G. DURHAM, Examiner.

10 D. H. THIEL, Assistant Examiner.

FRED C. MATTERN, ]R., Primary Examiner.

Claims

1. A DRIVE COMPRISING A SECTOR ANGULARLY MOVABLE ON A SUPPORT, A MEMBER MOVABLE TANGENTIALLY OF THE SECTOR ON A GUIDE WHICH IS MOVABLE RELATIVE TO THE SUPPORT TO DISPLACE SAID MEMBER TOWARD OR AWAY FROM THE SECTOR, FLEXIBLE BANDS ANCHORED TO SAID SECTOR AND TO SAID MEMBER FOR TRANSMITTING MOTION BETWEEN THEM AS THOUGH THEY WERE ROLLING TOGETHER IN NON-SLIP RELATION, AND MEANS FOR EXERTING PRESSURE BETWEEN THE SUPPORT AND THE GUIDE TO