US2195057A

US2195057A - Lapping apparatus

Info

Publication number: US2195057A
Application number: US167804A
Authority: US
Inventors: David A Wallace
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1937-10-07
Filing date: 1937-10-07
Publication date: 1940-03-26
Anticipated expiration: 1957-03-26

Description

March 26, 1940- D. A. WALLACE LAPPING APPARATUS Filed 001;. '7, 1937 3 Sheets-Sheet, 1

W lla/lid NAM. 5/. M w m A. m V L w A TTORNEYS.

March 26, 1940.

D. A. WALLACE LAPPING APPARATUS Filed Oct. 7, 19:57

3 Sh ets-Sheet 2 ATTORNEYS.

March 26, 1940. WALLACE 2,195,057

' LAPPING APPARATUS Filed Oct. 7, 1937 3 shee ts sheet 3 INVENTOR DA V/ D A. WALL/ 0E gg m fMfaZafi W A TTORNE Y5 Patented Mar. 26, 1940 LAPPING APPARATUS David A. Wallace, Detroit, Mich, assignmto Chrysler Corporation, Highland Park, Mich.) a corporation of Delaware Application October 7, 1937, Serial No. 167,804 I 3 Claims.

This invention relates to an improved lapping apparatus.

More particularly, the invention pertains to an improved apparatus for lapping end surfaces 5 such as the crowned ends of tappets and similar articles of the type commonly used in internal combustion engines and compressors.

One of the main objects of the invention is the provision of lapping apparatus of this charlO acter by which such relative movements between a lapping element and the surface operated upon are produced that tl e possibility of retracing of scratch lines in the surface is guarded against.

Another object of the invention is the provision of apparatus of this kind which is adapted to bring a lapping element into conformity with successively adjacent portions of crowned surfaces of different curvatures.

A further object of the invention is the provision of an improved driving connection between a lapping element of a tool and its driving member which accommodate self-adjustment of the operative surface of the lapping element to crown surfaces of different pieces of work.

Still further objects of the invention are to provide a lapping machine by which a plurality of pieces of work can be simultaneously lapped for a predetermined period of time; to provide a machine of this type which automatically predetermines the lapping period and which, at the end of the lapping period on one piece of work, discontinues the drive of that piece and moves the lapping tool which has been operating thereon, into an unobstructing position to facilitate convenient loading and unloading of the work while a plurality of other pieces of work are being lapped.

An illustrative embodiment of the invention is shown in the accompanying drawings, in which:

Fig. 1 is a top plan view, partly in section, and showing portions removed to disclose the underlying structure, of a machine embodying the invention.

Fig. 2 is a transverse vertical sectionalview taken on the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary vertical sectional view taken on the line 3-3 of Fig. 2.

Fig. 4 is a fragmentary radial sectional view taken on the line 4-4 of Fig. 1.

Fig. 5 is a fragmentary vertical sectional view taken on the line 5-5 of Fig. 2.

Fig. 6 is a fragmentary horizontal sectional view taken onthe line 66 of Fig. 5.

Fig. 7 is an end elevational view of the structure shown in Fig. 5 and taken as illustrated by the line '|--'l of the latter figure.

Fig. 8 is a fragmentary vertical sectional view taken on the line 8-8 of Fig. 2.

In the form of the invention shown in the drawings, the lapping apparatus includes a stationary base structure, generally designated by the numeral "I, having a central, vertically up- -standing hub part II in which a hollow spindle I2 is rotatably supported by rolling contact members l3 and M. Non-rotatabl'y fixed to the spindle I2 is a work supporting carriage E5 of circula1 shape having a central opening it through which the spindle I2 extends. The top portion of the work supporting carriage I5 is detachably secured to a radial flange ll extending outwardly from the spindle I! by cap screws l8. Provided on the work supporting carriage i5 are a plurality of arcuately spaced work-holding members, generally designated by the numeral HQ in Figs. 2 and 4. Each work-holding member includes a sleeve 20 seated in an opening 2| in the carriage I5 and detachably secured to the latter by cap screws 22. Provided in the interior of each sleeve 2!! is a pair of rolling contact bearings 23 in which a tubular spindle 24 is rotatably supported. The tubular spindle 24 has an open upper end portion for receiving the stem part 25 of a tappet 26. A plug member 21 extending into the lower end portion of the tubular spindle 24. has an upper extremity so formed as to provide a seat for the lower end portion of the tappet stem 25. A pulley wheel 28 is mounted on the exterior of the tubular spindle 24 and non-rotatably secured to the latter by a key 29. Belts 30 extend around the circumferentially arranged and arcuately spaced series of work-holding members 59 and are engaged in the belt grooves of the pulleys 28 thereof. The belts 30 also extend around a driving pulley 3! which is radially spaced outwardly from the series of workholding members in order to bring the belts out of contact with at least the pulleys of one of the work-holding devices 19, asillustrated in Fig. 1. During rotation of the work supporting carriage I5, as hereinafter more clearly set forth, each successive work-holding device is moved into radial alignment with the driving pulley 3! in order to bring the pulley of each successive work-holding member out of operative engagement with the belts 30.

The work supporting carriage i5 has a down! wardly extending lower structure on which is provided a worm gear ring 32 that is meshed with a worm 33 'by which the work supporting carriage i5 is drivingly rotated about the axis of the spindle I2. The drive pulley 3| of the work holding devices I9 and the worm 33 by which the work and tool carriages are rotated are driven from a common source including, a pulley I00 mounted on a shaft |0| which is journalled in housing I02. The pulley I00 may be driven by a motor (not shown) or other suitable means and its shaft |0| is provided with pinions I03 and I04 which transmit the drive to gears I05 and I06, respectively. The gear I05 is operatively connected with the worm 33 by belt and pulley apparatus, generally designated at I01, and the gear I06 is operatively connected by belt and pulley mechanism I08 and a shaft I09 with a gear unit 0, shown in Fig. 3, by which the drive pulley 3| is operated. The gear unit IIO includes a housing I I I in which one end of the shaft I09 is journalled.- A shaft I I2 having an axis disposed substantially normal to the shaft I09 is journalled in the housing I I I and drivingly connected therewith by bevel gears ||3. The drive pulley 3| is non-rotatably fixed to an external end portion of the shaft 2. p

The rotatable work supporting carriage I5 is provided with a lubricant discharge system which comprises discharge pipes 34 having their outlet end portions located in close proximity to the end portions of the tappets 26 which are to be lapped. The pipes 34 communicate with passages 35 in the Wall structure of the spindle I2 which leads from a lubricant well 36 formed in the stationary base structure of the machine. The lubricant well 36 is supplied with lubricant through a system of pipes, generally designated by the numeral 31. An upwardly extending circular flange 38 is provided on the rotatable work supporting carriage I5 for preventing outward throwing of lubricant. The lubricant discharged from the pipes 34 upon the work is allowed to run down into an annular trough 39 formed in the carriage I5 from which it is discharged into a well 40 provided in the stationary base structure ID. The well 40 has an outlet pipe 4| communicating therewith for returning lubricants to the base structure from which it was supplied through the system of pipes 31.

Provided on the'upper end portion of the spindle I2 is a reduced end section 42 on which is non-rotatably mounted a lapping tool carriage, generally designated by the numeral 43, and comprising a central sleeve 44 on which radially extending arms 45 are detachably secured by cap screws 46. Each radially'extending arm 45 has a vertically extending channel-way 41 formed in its outer extremityfin which a lapping tool, generally designated by the numeral 48, is slidably mounted. Each lapping tool 48 comprises a base structure 49 having flanges 50 slidably engaged in the channel-ways 41 of the arms 45 and an electric motor 5|, or other suitable driving mechanism, having a shaft 52 on the lower end of which is mounted a disc 53. The driven shafts. 52 of each lapping tool are disposed above and associated with one of the work-holding members I9, respectively. The rotative axis vof the driving shaft 52 may be concentric with the axis of rotation of the work supported by the hollow spindles 24, but, for reasons hereinafter set forth, in the lapping of certain types of crowned surfaces, it is preferable to have the axis of rotation of the shaft 52 arranged in eccentric relationship with respect to the axis of rotation. of the work.

A disc 54 having an inverted cup-shaped lapping element 55 preferably comprising lapping thedisc 53 and which are threaded in counterbored apertures 58 in the disc 54. A coil spring 59 seated in the counterbore of the aperture 58 bears between the

discs

53 and 54 so as to yieldably urge the latter disc axially of the shaft 52 and to yieldably resist lateral movement of the disc 54 with respect to the disc 53. A drive pin 60 mounted on the disc 53 is received in an oversize aperture 6| provided in the disc 54 for transmitting the drive from the shaft 52 to the disc- 54 and lapping elements 55 carried thereby. The lapping element 55 is preferably detachably mounted on the disc 54 by a screw 62 and located on the disc 54 in eccentric relationship with respect to the axis of rotation of the shaft 52.

In the form of the invention illustrated, electrical power is supplied to the motors 5| of the lapping tool 48 by conductors 63 which extend through a tube 64 mounted on the base structure I0 of the machine and extending through a passage 65 in the spindle I2. Each of the conductors 63 is electrically connected to a slip ring 66 mounted on the exterior of the tube 64 and confined in ahousing 61 carried by and adapted to rotate with the spindle I2. The slip rings 66 remain stationary during rotation of the housing 61. Disposed in the housing 61 is a horizontal plate 68 on which posts 69 are mounted. Each post 69 is provided with a brush 10 which bears against one of the slip rings 66. The brushes 10 rotate in unison with the casing 61 and spindle I2 and they establish electrical connection between the slip rings 66 and bus bar rings 1| disposed in the housing 61, as illus trated in Fig. 2. Each electrical motor 5| of the respective lapping tools 48 is provided with conductors 12 which are respectively electrically connected with the bus bars-1|.

The lapping tools 48 normally assume their lowermost positions, as illustrated at the left in Fig. 2,by virtue of their weight. As each lapping tool and its associated tool holding member I9, reaches the position indicated by the numeral 13 in Fig. 1, at which the driving connection between the belt 30 and the work-holding member is interrupted, the lapping tool is lifted to facilitate convenient removal of the tappet 26 after the latter has been lapped, and replacement of a tappet to be lapped. in the work holder. This, is accomplished by providing a lever 14 which is pivotally mounted on each of the arms 45 of the tool carriage and arranged so that its outermost end engages the lower extremity of the base portion 49 of each lapping tool 5|, respectively. During rotation of the work and tool carriages I5 and 45, respectively, each of the tools 48 are successively lifted to accommodate removal of the work 26 and replacement of work in the work-holding members 9. This is accomplished by the provision of cam followers, generally designated by the numeral 15, which comprise rods 16 slidably mounted in tubes 11 mounted in circumferentially arranged apertures 18 in the central portion of the work supporting carriage I5. One cam following device 15 is provided for operating the lever 14 of eachrespective lapping tool 48. The upper end portion mounted on the upper extremity of the hub portion H of the base structure ill. The cam track BI is provided with an upwardly extending projection 82 which lifts the cam follower associated with each respective lapping tool to rotate the lever 14 thereof and lift the tool as the latter is moved into the loading and unloading position designated by the numeral I3 in Fig. 1.

During operation of the foregoing apparatus, a plurality of tappets or other articles are simultaneously lapped for a predetermined period of time, as determined by the time required to produce one complete rotation of the work carriage l5 from the loading and unloading station 13. During this lapping period, the lapping element 55 is revolved While the work is rotated; In the illustration shown in Fig. 4, the lapping element 55 has an outer diameter slightly lessthan the diameter of the crowned surface of the tappet being operated upon. Relative movements accommodated between the discs 54 which supports the lapping element 55 and the discs 53 of the driven shafts 52 permits the working surface of the lapping element 55 to become accommodated to the curvature of successively adjacent portions of the crown surface of the tappet. In this manner all portions of the crown surface of the tappet are subjected to uniform action of the lapping element 55, which by reason of its revolving movement accompanied by the rotational movement of the work does not tend to retrace any of the scratch lines produced by the work by localized harsh particles of lapping material.

Although but one specific embodiment of the invention is herein shown and described, it' will be apparent that various changes in the size, shape and arrangement of parts may be made without departing from the spirit of my invention.

What I claim is:

1. Lapping apparatus comprising a work support, a spindle on said work support for drivingly rotating a piece of Work and retaining a surface of the latter which is disposed transversely of its axis of rotation in position to receive a lapping operation, a lapping tool adjacent said sup- .port including a rotative driving member having an extremity in opposed spaced relationshipwith respect to said surface, means for supporting said driving member for rotation about an axis substantially parallel to but laterally spaced from the axis of said spindle, a lapping device between said surface and said extremity of said driving member having a lapping surface engageable with said surface of said work and extending on respectively opposite sides of the axis of rotation of the latter throughout the entire course of relative movement of said work and lapping surface, means drivingly connecting said member and lapping device including connecting elements having loose fitting engagement with one thereof for accommodating movement of said lapping device axially and transversely of said driving member and so constructed and ar ranged as to retain said lapping device ineccentric relationship with repect to the rotative axis of said driving member and resilient members bearing between said driving member and said lapping device for yieldably urging the latter against said surface of said work.

2; Apparatus for lapping a crowned extremity of a tappet comprising a support, a spindle on said support for drivingly rotating said tappet and retaining said crowned extremity thereof in position to receive a lapping operation, a rotatable driving member adjacent said spindle having an axis parallel to the axis of the latter but spaced laterally therefrom and having an end portion disposed in spaced opposed relationship with respect to said tappet extremity, a lapping element axially slidably and transversely movably mounted on said extremity of said driving member in eccentric relation with respect to its axis and having a ring shaped abrading surface provided with a central opening extending on respectively opposite sides of the rotative axis of said work throughout all portions of the course of relative movement of the latter and said abrading surface engageable with the crowned surface of said tappet, and resilient means for yieldably urging said lapping element toward said tappet and adapted to accommodate movement of said lapping element to conform with the crowned extremity of said tappet during operation of said apparatus.

3. Apparatus for simultaneously lapping the ends of a plurality of tappets including a basestructure, a rotatable carriage on said base structure having a pluralityof arcuately spaced rotatable members thereon ach adapted to support a tappet with its end sur ace exposed to receive a lapping operation, a t ol carriage rotatably mounted on said base structu e in axially spaced substantially concentric rel ionship with respect to the axis of said work carriage, a plurality of lapping tools each comprising a rotative driving member having a lapping element axially and laterally yieldably mounted thereon in ec-,

centric relationship with respect to its rotative axis, each tool being so mounted on said tool carriage as to accommodate movement of its respective lapping element toward and away from an end surface of one of said tappets respectively, means for simultaneously drivingly rotating each of said carriages, apparatusfor simultane-