US2062699A - Burnishing apparatus - Google Patents

Description

Dec. '1, 1936.

J. M. CHRISTMAN ,0 ,699

'BURNISHING APPARATUS Fild May 4, 1934 2 Sheets-Sheet l Dec. 1, 1936. CHRISTMAN 2,062,699

BURNISHING APPARATUS Filed May 4, 1934 2 Sheets-Sheet 2 Patented Dec. 1, 1936 UNITED STATES nrmmsnmo APPARATUS John M. Christman, Detroit, Mich, assignor to Packard Motor Car Company, Detroit, Mich, a corporation of Michigan Application May 4, 1934, Serial No. 723,987

17 Claims. (Cl. 29- 27) This invention relates to a method of and apparatus for burnishing machine elements, and is more particularly concerned with the burnishing of the circumferentially toothed rollers commonly employed in automobile steering gear for engagement with and operation by the usual worm at the lower end of the steering column. These rollers are employed in lieu of the more conventional worm gear or sector for the purpose of reducing friction in the steering gear.

It is of course essential that proper meshing of the roller with the worm be eifected and accurate and smooth finishing of both the roller and the worm is important. By the present invention it is possible to produce true and extremely smooth working surfaces on the teeth of the roller and at the same. time vto harden and toughen these surfaces, the result of the burnishing operation being much more satisfactory so in these respects than if grinding of the roller is' resorted to. The invention contemplates the employment of two or more master rollers which are grooved to receive the teeth of the roller to be burnished and which are suitably hardened,

the roller to be burnished being received between these master rollers and being rotated with the simultaneous application of pressure thereto.

- It is a more specific object of the invention to provide a plurality ofmaster burnishing rollers which are so supported and position'ed'that the roller to be burnishedcan be readily located therebetween and the requisite degree of pressure applied, means being provided whereby this degree of pressure may be predetermined.

In one embodiment of the invention a machine capable of automatic operation is contemplated, the stock from which the rollers are formed being periodically advanced and the rollers being successively completed by grooving the stock, burnishing the grooved stock, and severing the burnished roller. Preferably the grooving and severing operations are combined, one roller being severed simultaneously with the grooving of the stock to form the succeeding roller by a single 45 13001.

Figure 2 is an end elevation partly in section of'a portion of the construction sh wn in Fig- 55 i I Further objects and features of the invention Figure 3 is a side elevation corresponding to Figure 2;

Figure 4 is a plan view of a'modified type of machine capable of both forming and burnishing the rollers;

Figure 5 is an end elevation of the structure shown in Figure 4;

Figure 6 is a sectional view of one type of steering gear illustrating the manner in which the product of the machine disclosed herein may 10.

', In the form of the invention shown in Figure 1 of the drawings, a conventional machine of the I adjustable bed type is disclosed, this machine comprising a base l0 having a standard 12 rigid therewith and extending vertically therefrom, and 25 a bed or table I 3 supported on the base III for movement in several directions with respect thereto. Secured rigidly to the table I3 is a carrier M on which are joumalled for rotation a plurality of master rollers l6 and I1, preferably 30 two in number as illustrated in the drawings. An arm l9 rigid with and dependent from the standard l2 carries a third master roller 20 which is joumalled for rotation on the arm I9, for instance by means-of a shaft 2| extending through the arm and rotatable by a pu ley 24, the pulley and roller 20' being secured to-the shaft. The axes of the master rollers l6, l1, and 20 are parallel and preferably horizontal, the axis of the roller 20 being shown as located above the axes of the rollers It and I1. It will nevertheless be ,understood that this arrangementis by no means essential and that the relative positions of these rollers may be altered as desired so long as the axes thereof remain substantially parallel. It is convenient, howe ver, in describing and defining the invention to refer to the rollers l6 and H as located beneath the roller 20.

The carrier M for the rollers l6 and H ma be secured to the bed l3 by bolts 22 passing through the base '23 of the carrier and threaded in the bed, locating keys 25 secured to the carrier and engaging corresponding'grooves 26 in the bed being provided to ensure that the carrier will not be twisted on the bed during operation of the machine.

The carrier i4 and the bed I3 are displaceable in. a plane substantially perpendicular to the axes of the rollers l6, l1, and 20, and for this purpose are supported for sliding movement on a member 21; displacement of the bed and carrier and retention thereof in any desired position of adjustment beingeifected by the threaded rod 29 operable by the handle 30 in the conventional manner. It will be observed that the axis of the roller 16 is spaced to a suflicient extent from the axis of the roller 20 to permit the roller l6 to move under the roller 23 from one side thereof to. the other, movement of the carrier and bed to. the right being limited by the engagement of abutments 32 and 33 on the bed and the member 21 respectively. One of these abutments is adjustable in the direction of displacement of the bed. Thus the abutment 32 may be supported on the bed l3 by means of a bolt 35 extending through a slot 36 in the bed so that the abutment may be displaced along the slot 36 and may be clamped in any desired position.

The member 21 is preferably, although not necessarily, supported for sliding movement in the axial direction of the rollers l6, l1, and 20, for instance on a member 38, suitable screw and nut gearing actuable by the handle 39 being provided to adjust the position of the member 21. The member 38, and the elements of the machine sup-' ported thereby, including the table I3, are ad- Justable vertically, being preferably guided in this vertical movement on the standard H2 in the conventional manner. This vertical movement may be efiected by means of a threaded shaft 40 engaginga nut 4| carried in the base Ill, the shaft 40 being joumalled in the member 38 as indicated at 42 and being rotatable by bevel gearing 44 which is in turn actuated by. the handle 45.

, The structure thus far described for effecting relative adjustment of the axes of the roller 23 and of the rollers l6 and I1 is conventional and the details thereof form no essential part of the present vention. Such arrangements are commonly foun in milling machines and the like which ordinarily-provide for vertical adjustment as well as horizontal adjustment in two directions of a work table or other support.

The master rollers I 8, l1, and 20 are preferably similar so far as the configuration of their circumferentially' toothed portions is concerned although they may differ in diameter. It will be observed that each roller is grooved as indicated at 48, two grooves being provided to accommodate and to receive in interlocking relation the teeth 49 on the roller 50 to be burnished which are shown more particularly in Figures 3, 6, and 7 of the drawings, it being apparent that the number of grooves provided in the master rollers will equal the number of teeth formed on the roller t].

While in the preferred form of the invention a roller having two circumferential teeth is formed, rollers having a less or greater number of teeth can obviously be burnished by the same operation. I V

The machine thus far described is initially adjusted so as to permit the burnishing of rollers in rapid succession with the least possible delay. Thus the handle 39 is operated to align the rollers l6, I1, and 20 in an axial direction, the correct relative position being indicated in Figure 2 of the drawings. The handle 45 is then operated to raise or lower the table l3 and the carrier M to the proper vertical position, this position being determined by displacing the carrier l4 laterally until the roller I3 is directly beneath the roller 20 and inserting a gauge or feeler 52 between these rollers to determine the correct spacing thereof. The carrier I4 is then displaced to the right by operation of the handle 30 to a position in which the rollers l1 and 20 are spaced by the thickness of the gauge or feeler 53 as shown in Figure 1 of the drawings. The abutment 32 is then engaged with the abutment 33 and secured in position on the table, it being observed that displacement of the table and carrier M to the right on each operation is thereby limited.

The handle 30 is then manipulated to displace the table l3 and carrier M to the left, a roller 50 to be burnished is placed in position between the master rollers l6 and ll, and the table and carrier are then displaced to the right to bring the roller 50 into engagement with the master roller 20 and apply the necessary pressure between all of the rollers, the shaft 2| being simultaneously rotated and the master rollers and the roller 50 being rotated thereby. If desired the rollers may be cooled during the burnishing operation by causing flow of liquid such as oil over the same. On completion of the operation, the table and carrier are moved once more to the left and the burnished roller 5!! replaced by the succeeding roller, the foregoing operations being then repeated.

Obviously a machine of this character can be made entirely automatic, the lateral displacement of the table and carrier from the operative to the inoperative position and vice versa being effected by suitably designed cams, and the rollers 50 being successively delivered and removed from the carrier by conventional automatic feeding mechanism, it being only necessary to make slight adjustments from time to time to compenthese rollers.

When formed in this way, the rollers 50 will mesh accurately with hour-glass worms such as shown at 46 in Figure 6 of the drawings, the roller being preferably supported for rotation on an axis 5| parallel -to the worm in a carrier 54, the latter being in turn rotatable about an axis perpendicular to the axis of the roller in an arm 51, this second rotational axis being provided to accommodate the roller to the varying helix angle of the worm. The arm 51 constitutes in effect the equivalent of the usual worm gear and is connected in the conventional manner to the steerable road wheels of the vehicle. The structure shown in Figure 6 forms no part of the present invention and is included to facilitate an understanding of the nature of the rollers 50 and their function.

Referring now more particularly to the form of the invention shown in Figures 4 and 5, it will be observed that the rollers 50 arev illustrated as formed on stock 55, the latter being secured in and rotated by a suitable work holder 56. While the work holder56 is shown diagrammatically in the drawings to simplify the description and illustration of the invention, I may use for this purpose a conventional type of screw machine which is automatically operable in known manner to periodically advance the stock axially and to rotate the stock, theperiodical advance being effected by suitably designed cams or the like.

At one side of the stock a carrier 58 is provided, this carrier being secured to a table 59 which is in turn supported on a base 60 for sliding movein which are supported for rotation two or more master rollers, of which three are preferably provided, these rollers being designated 64, 65, and 66. The axes of the rollers are parallel to the axis of the stock and may be so relatively positioned that as a roller 50 to be burnished passes between the rollers 64 and 86 and into engagement with the roller 65 with the desired pres-- sure, substantially equal pressure will be applied thereto by the rollers 64 and 66.

At the other side of the stock a device for forming and preferably for cutting ofi the rollers is disposed, this device consisting of; a table 58 which is mounted for sliding movement on the support 60 transverse of the axis of the stock 55 and which has rigidly secured thereto a tool supporting bracket 10, the latter carrying a-tool 'H formed as shown more particularly in Figure 4 of the drawings with two cutting edges 12,

adapted to form corresponding grooves in thestock, and a severing edge ll adapted to remove a formed and burnished roller from the stock.

The bumishing device and the cutteror grooving device are alternately brought into engagement with the s eck 55 by lateral displacement with respect th etc, a common operating means being preferably provided. Thus'nuts l6 and 11 may depend from the bumishing device and the grooving device respectively, these nuts being engaged by a threaded rod 19 supported in any suitable manner for rotation and against length-"' wise displacement in the base 60, a handle 80 being provided to effect rotation of the rod and simultaneous displacement of the two devices in the same direction.

With the parts in the position shown in Figure 4, the stock 55 is advanced axially through a distance corresponding to. the length of the element which may be assumed to have been formed and burnished. The cutting device is then displaced to the left to engage the stock,

plete the bumishing operation, the bumishing device and the-cutting device being thereupon displaced to the left and the stock again advanced while disengaged from both devices as hereinbetore explained. I

In order that the pressure applied by the master rollers to the roller to beburnished maybe determined in advance, an arrangement similar to that shown in Figure 1 may be provided; thus" abutments 82 and 83 located on the table 59 and the base 50 respectively may be employed, Once! these abutments being adjustable. v

The entire operation of the machine shown in Figures! and 5 may be automatic, displacement;

oi the bumishing device and the cutting device being effected by suitable mechanism serving toperiodically rotate the threaded rod I9 in timed relationwith the axial advance of the st'ock 55. In thisconnection it may be pointed out that the displacement of the bumishing rollers with re- 1 spect to the stock is relative, that is to say. the

stock may be displaced laterally while the burnishing rollers and the cutting device "are maintained in a stationary position. Similarly, in the three master elements.

first described form of the invention) the masterezzz roller 20 may be displaced laterallyoi'the axis thereof while the rollers it and H are retainedagainst movement. Various other changesin the structure herein described will occur to one skilled -in the art to which the invention relates and all modifications are contemplated such as fallwithin the scope of the appended claims. Having thus described the invention, what is claimed as new and desired to, be secured by Letters Patent is: J 1. In apparatus for bumishing circumferentiall'y toothed elements, the' combination with a support, of a circumferentially toothed master element rotatably mounted on said support, at

least two master elements carried by said support for rotation about spaced axes parallel to the axis of said first named element and for lateral displacement with respect to said first named element, said master elements receiving therebetween a circumferentially, toothed element to be burnished, means for imparting relative lateral displacement to said second named master elements' and said first named master element to apply pressure in agenerally radial'direction to the element to be burnished, and means for rotating said elements.

2. In apparatus .for bumishing circumferen tially toothed elements, the combination with a support, of a circumferentially toothed master element rotatably mounted on said support, at least two master elements carried by-said support for rotation about spaced axes parallel to the axis of said first named element and ,for lateral rectilinear displacement as a unit with respect to said first named element, said master elements receiving therebetween a circumferentially toothed element to be burnished, means for imparting relative lateral displacement to said second named master elements and said first namedmaster element to apply pressure in a generally and means for rotating saidelements.

3. In apparatus for bumishing circumferentially toothed elements, the combination with a support, of a circumferentially toothed master' element rotatably mounted on said support, two master elements carried by said support for rotation about spaced-axes parallel to the axis of said first named element and for lateral rectilinear displacement as a unit with respect to said first named element, said master elements re- .radial direction to the element to be burnished,

ceiving therebetween a circumferentially toothed element to be bur'nished, means for imparting relative lateral displacement to said. second named master elements and said first named master element to apply pressure in a generally radial direction-to the element to'be burnished, and means for rotating said elements, one only of said two second named master elements being so positioned as'to permit displacement thereof to a position adjacent either side of'said first "named master element to facilitate the position-.

ing of the elementto'be burnished between the 4. In apparatus for bumishing circumi erenr tiallytoothed elements, the combination with a a support, of a circumterentially toothed master element rotatably mounted on said support, a

carrier laterally 'displa'ceable on, said support with respect to said master element, two circumferentially toothed master elements supported for rotation on said carrier about axes parallel to. the",

axis-oi said first named'master element, the plane elements and the element to be burnished in directions generally radial of the latter, and means for supporting and rotating the element to be burnished, whereby said master elements are rotated therefrom, said last named means comprising a rotatable stock holder for supporting and rotating the stock on which the element to be burnished is formed, and means for engaging and simultaneously forming an element on said stock and severing the preceding burnished element from the stock.

16. In apparatus for burnishing circumferentially toothed elements, the combination with a support, of a plurality of circumferentially toothed master elements carried by said support for rotation about parallel axes and receiving the toothed element to be burnished.- therebetween, means for applying pressure between said master elements and the element to be burnished in directions generally radial of the latter, said means comprising a relatively laterally displaceable support for the element vto be burnished, and an adjustable stop means for limiting the relative displacement of said said supports to limit the I pressure applied to said elements.

1'7. In apparatus for burnishing circumferentially toothed elements, the combination with a support, of a plurality of circumferentially toothed master elements carried by said support for rotation about parallel axes and receiving the toothed element to be burnished therebetween, means for applying pressure between said master elements and the element to be burnished in directions generally radial 01' the latter, said means comprising a relatively laterally displaceable support for the element to be burnished, and an adjustable stop means for limiting the relative displacement of said supports to limit the pressure applied to said elements, said support for the element to be burnished being rotatable, whereby said master elements may -be rotated therefrom.

JOHN M. CHRISTMAN.

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