US2735233A

US2735233A - henkel

Info

Publication number: US2735233A
Authority: US
Publication date: 1956-02-21
Anticipated expiration: 1973-02-21

Description

Feb. 21. 1956 F. J. HENKEL LAPPING MACHINE 4 Sheets-Shee't 1 Filed Aug. 15, 1952 EV QJ M 5 EN 9 \Q n T 6 /r H x W IL L fl l I N Q l l l 1 s To M EMHH HMEHE PM a. m d w RN AWN NWN Row w Feb. 21, 1956 F. J. HENKEL LAPPING MACHINE 4 Sheets-Sheet 2 Filed Aug. 15, 1952 Feb. 21. 1956 F. J. HENKEL LAPPING MACHINE 4 Sheets-Sheet 3 Filed Aug. 15, 1952 wmw vmw Feb. 21, 1956 F. .1. HENKEL LAPPING MACHINE 4 Sheets-Sheet 4 Filed Aug. 15. 1952 Q a INVENTOR.

gmy dafl m/ flmwzflay ee QQ Q3 NE m? 0mm EN United States Patent LAPPING MACHINE Ferdinand J. Henkcl, Royal Oak, Mich, assignor to Lamina Dies and Tools, Inc Berkley, Mich, a corporation of Michigan Application August 15, 1952, Serial No. 3%,587

7 Claims. (Cl. 51--5tl.)

This invention relates to lapping machines and, in particular, to rotary lapping machines.

One object of this invention is to provide a precision lapping machine which will quickly and accurately lap bores, especially those of small diameter, and either straight or tapered, with greater uniformity and much less breakage of laps than in prior machines.

Another object is to provide a precision lapping machine which automatically retracts the lap after it has rotated a predetermined amount, so as to prevent drying out with consequent freezing, jamming or breaking of the lap and insure even and ample feeding of the lapping compound to the bore, without requiring close attention on the part of the operator.

Another object is to provide a precision lapping machine of the foregoing character wherein the lap is mounted on a carriage which is automatically advanced as the lap makes its way into the bore being lapped, the lap being automatically retracted or backed off at approximately every revolution for the purpose previously stated.

Another object is to provide a precision lapping machine of the foregoing character, wherein the retraction and advance of the lap and the advance of the carriage are controlled electrically by an electrical circuit including precision instruments such as micro-switches.

Other objects and advantages will become apparent during the course of the following description of the accompanying drawings, wherein:

Figure l is a top plan view of a precision lapping machine according to one form of the invention;

Figure 2 is a side elevation, partly in vertical section, of the lapping machine shown in Figure 1;

Figure 3 is a right-hand end elevation, partly in vertical section, of the lapping machine of Figures 1 and 2, showing the ratchet mechanism for advancing the carriage;

Figure 4 is a fragmentary side elevation of the ratchet mechanism, partly in vertical section, taken along the line 44 in Figure 3;

Figure 5 is a fragmentary vertical section taken along the line 5-5 in Figure 4;

Figure 6 is an enlarged fragmentary horizontal section taken along the line 6-6 in Figure 2, showing the spindle construction;

Figure 7 is a vertical cross-section taken along the line 7-7 in Figure 6;

Figure 8 is a fragmentary vertical cross-section taken along the line 88 in Figure 6, showing the drive pulley and spindle drive connection;

Figure 9 is a fragmentary vertical longitudinal section taken along the line 9-9 in Figure 1, showing the spring plunger and its adjustment mechanism; and

Figure 10 is a fragmentary horizontal section taken along the line 10-10 in Figure 2, showing the arrangement and adjustment of the micro-switches, for controlling the feeding and retraction of the lap.

General description Hitherto, the precision lapping of small bores, especially, tapered bores, has been very laborious and expensive because of the difliculty of performing the lapping operation without breaking the lap. Such small bores, especially those formed in hardened steel which is too hard to broach and too small or otherwise impractical to grind, have been lapped in drill presses with manual feed and retraction of the lap while the lapping compound is fed manually to the lap or bore. With such a prior arrangement, however, lap breakage is frequent and unpredictable because the slightest drying out ofthe lap or bore causes it to -freeze or jam immediately, snapping off in the bore and wasting time, labor and expense in removing it and replacing it with a new lap. Moreover, this former method does not give accurately dimensioned and precisely formed holes, and it is not possible to control the operation of the machine so as to give uniform results.

The lapping machine of the present invention provides a rotary lap holder which is automatically advanced into and retracted from the bore being lapped after a predetermined amount of rotation, such as approximately every revolution, automatically backing oif the lap so as to loosen it and insure the proper feeding of the lapping compound, which is in the form of a liquid or thin paste. In this manner, the lap is kept constantly provided with lapping compound so that it can never dry out. At the same time, the carriage on which the lap holder is Irotatably mounted is automatically advanced as the lap works its Way into the bore while performing its lapping operation.

Referring to the drawings in detail, Figures 1 and 2 show a precision lapping machine, generally designated 14), according to one form of the invention as consisting generally of a base or supporting structure 11 upon which is mounted a work-holding and rotating unit 12, a lap rotating and reciprocating unit 13, and a carriage feeding unit 14. Each of these units is described in detail below. The base structure 11 includes an elongated hollow base 15 of inverted shallow box shape with a top Wall 16, end walls 17 and side Walls 18 (Figures 2 and 7). A hollow chamber or recess 19 is formed in the base 15 for lightening the construction. The base 15 near one end is provided with an upstanding pedestal or support 20 and near its other end with an upstanding boss 21, the former carrying the work holding and rotating unit 12 and the latter the lap-rotating and reciprocating unit 13. The carriage feeding unit 14 is mounted on the right-hand or rearward end of the base 15.

Work holding and rotating unit The pedestal or support 20 is provided with bores 23 and 24, the axes of which are parallel and disposed in a substantially horizontal plane. These bores 23 and 24, for purposes of simplicity .of' illustration, are shown as plain bearing bores, but it will he understood that they may contain anti-friction bearings of any suitable type for rotatably supporting a pair of

parallel shafts

25 and 26 respectively, the latter being'the work-holding spindle. Keyed or otherwise drivingly secured to the shaft 25 at one end thereof is the hub 27 of a drive pulley 28 which is connected by a suitable belt to a source of power such as an electric motor. Also keyed or otherwise drivingly secured to the shaft 25 between the pulley hub ZTand the support 20 is a gear 29 which meshes. with a gear 30. The latter is keyed or otherwise drivingliy'secured to one end of the shaft 26 in such a manner that when the pulley 28 is rotated, the rotation is transmitted through the gears 29 and 34) to the spindle 26.

Threaded upon or otherwise drivingly secured to the shaft or spindle 26 .on the opposite side ofthe support 20 from the gear 30 is a conventional work holding chuck 31 of any suitable type, the type shown having a head 32 secured to the shaft .26, a barrel 33 of cylindrical or drumshaped form, and radially-reciprocable and adjustable work-holding jaws 34 which are movable to and fro radially toward and away from the axis of rotation ofthe shaft 26. Alternatively, the chuck 31 may consist of a conventional collet chuck in which case the spindle 26 is hollow to receive the collet chuck, as is customary with such chucks. A workpiece W is mounted in the chuck 31 and has a bore B which is to be lapped in the machine 10. The workpiece W is so clamped in the chuck 31, as by the jaws 34, as to position the axis of the bore B in coincidence with the axis of rotation of the spindle 26. The bore B may be straight or tapered, it being shown as tapered for purposes of illustration. Moveable into and out of the bore B is a lap L of a form similar to the ultimate form desired for the bore B and having a shank S which is rotatably mounted in the lap holding and rotating unit 13, as described below.

7 The shaft on the side of the support 20 opposite the gear 29 is provided with a flanged portion 37 containing a socket 38 coaxial with the shaft 25. Secured as by the pin 39 in the socket 38 is a shaft 40 for conveying power to the lap holding and rotating unit 13 as well as to the carriage feeding unit 14. The shaft 40 at its rearward end is secured as by the pin 41 in a socket 42 of an eccentric shaft 43 which is rotatably mounted in a bearing bore 45 of a bearing bracket 46 extending upward from the rearward end wall 17 of the base 15 and secured thereto as by the screws 47 (Figures 1 and 3). The cam shaft 43 terminates at its 9 rearward end in a flanged eccentric portion 48 of circular cross-section, the center of which is offset relatively to the axis of rotation of the shaft 43.

Lap rotating and reciprocating unit The lap rotating and reciprocating unit 13 is mounted upon a carriage 50 which is provided with a dovetail lower portion 51 slidable to and fro longitudinally upon the bottom surface 52 of a recess 53 (Figure 7). The dovetail portion 51 is held down and guided for longitudinal reciprocation by dovetail guide bars or gibs 54 which are bolted or otherwise secured as at 55 to the upstanding boss 21 of the base 15. The screws 55 are threaded into threaded sockets 56 on opposite sides of a longitudinally-disposed counter recess or groove 57 formed in the upstanding boss 21 and extending downward below the level of the bottom surface 52 of the recess 53. Extending downwardly into the longitudinal groove 57 is a nut 58. The nut 58 is provided with a threaded bore 59 which receives a correspondingly threaded portion 60 of a screw shaft 61, the rearward portion 62 of which is journaled in the bearing bore 63 of a bearing bracket 64 which is bolted or otherwise secured as at 65 to the rearward end wall 17 of the base 15 (Figure 4). A shoulder or flange 66 is provided on the screw shaft 61 adjacent the bearing bracket 64. The rearward portion 67 of the screw shaft 61 is smooth but its end is threaded as at 68 to receive a retaining nut 69 for holding in position certain portions of the carriage feeding unit, as described subsequently below.

The carriage 50 is provided on one side with horizontally-extending spaced parallel bracket portions 70 which are bored coaxially at 71 to receive flanged bearings or discs 72 secured as by the screws 73 to the threaded holes 74 in the brackets 70 and having coaxial bearing bores 75 for receiving the opposite end portions 76 and 77 (Figure 6) of a hollow cam shaft 78 provided with an eccentric cam 79 preferably integral therewith. The hollow shaft 78 is provided with a radial countersunk slot 80 (Figures 6 and 7) which receives a correspondingly-shaped key 81 of T-shaped form held in position by a retaining ring 82 encircling the hollow shaft 78. The shaft 78 is provided with a longitudinal bore 83 from end to end thereof for the passage of the shaft 40, the latter being provided with a longitudinal keyway or groove 84 receiving the key 81 and transmitting rotational motion thereto while permitting relative longitudinal motion therebetween. A sheel metal housing 85 of U-shaped cross-section is secured at its opposite ends as by the screws 86 to the outer surfaces of the brackets 70 (Figure 7), thereby enclosing the hollow cam shaft 78 and its associated mechanism and protecting them from dust, as well as retaining lubricant therein.

Drivingly secured as by the Woodruff key 87 to the rearward end portion 77 of the hollow cam shaft 78 is the hub 88 of a pulley 89 held in position by a retaining ring 90 threaded upon the threaded end 91 of the shaft end portion 77 (Figure 6). The pulley 89 is preferably a V-grooved pulley receiving an endless V-belt 92 which drivingly engages a 'V-groove pulley 93, the hub 94 of which is provided with a bore 95 loosely and rotatably engaging a cylindrical bearing surface 96 upon the reduced diameter tubular portion 97 of a flanged hearing disc or head 98 which is secured in a counterbore 99 of a horizontal bore 100 by the screws 101. The reduced diameter portion 97 is threaded as at 102 to receive a similarly threaded retaining ring 103.

Extending rearwardly from the pulley 93 is a cupshaped portion or flange 104 (Figures 2 and 6) containing a pair of parallel-sided notches 105 extending axially inward from the rearward edge or end 106 thereof. Mounted in and drivingly engaging the notches 105 which are located diametrically opposite one another are two contact rollers 107 rotatably mounted upon the reduced diameter end portions 108 of a spider 109, the hub 110 of which is drivingly secured as by the Woodruff key 111 to a keyway 112 in the end portion 113 of the lap chuck spindle 115. The reduced diameter end portions 108 of the spider 109 are threaded to receive retaining nuts 116 by which the rollers 107 are held in position against the shoulders 117 formed at the inner ends of the reduced diameter portions 108. The extreme rearward end portion 118 of the spindle is threaded to receive a retaining nut 119 which holds the spider 109 in position upon the end of the spindle 115. In this manner, rotation is transmitted from the pulley 93 to the spindle 115 by way of the roller and slot driving connection 106, 105, yet at the same time, the spindle 115 can be reciprocated axially without interrupting the discdriving connection, due to the fact that the notches 105 are elongated sufficiently to permit this, the depths of the notches 105 being greater than the radii of the rollers 107.

The rearward portion of the spindle 115 is rotatably supported in a bearing bore 120 in the bearing head 98, the forward portion of this spindle 115 being similarly journaled in a bearing bore 121 within a flanged bearing head 122 which is secured by the screws 123 in the counterbore 124 in the forward end of the bore 100. Mounted on the forward end of the spindle 115 is a conventional lap chuck 125 having the usual jaws 126 which are adapted to receive and securely hold the shank S of the lap L.

In order to reciprocate the spindle 115, the latter is provided with spaced parallel annular flanges 130 and 131 (Figure 6) located adjacent an annular enlargement 132 in the carriage 50. Engaging the forward face 133 of the flange 130 is a contact roller 134 mounted in a notch 135 and upon an axle 136 in one arm 137 of a bell crank 138, the hub 139 of which is pivotally mounted upon a pivot pin 140 which in turn is secured in coaxial bores 141 (Figure 7) in spaced parallel upper and

lower ears

142 and 143 respectively. The arm 137 of the bell crank 138 extends through an opening 144 in the side wall of the carriage 50 and communicates with the interior chamber 145 within the housing 85 (Figures 6 and 7).

The remaining arm 146 of the bell crank 138 is provided with a notch 147 (Figure 6) containing a contact roller 148 and axle 149 therefor, the roller 148 engaging the eccentric peripheral surface 150 of the cam 79, the surface 150 being of approximately spiral form having an inclined step 151 (Figure 7) serving as a ramp interconnecting the opposite ends of the spiral cam surface 150. The roller 148 is constantly urged into engagement with the cam surface 150 by the helical compression spring 152 mounted in a socket 153 in the side wall of the carriage (Figure 6).

Mounted between the flanges 131 on one side of the spindle (Figures 6 and 7) is a roller 155 mounted on a pivot pin or axle 156 seated in a hole 157 in the lower end of a vertically-disposed rocking lever 158, the hub 159 of which is pivotally mounted upon a pivot pin 160 (Figure 7) seated at its opposite ends in. a bore 161 and socket 162 in the carriage 50 on opposite sides of a vertical opening 163. The upper end of the lever 158 is bored as at 164 to receive a pivot pin or axle 165 upon which is mounted a roller 166 (Figures 7 and 9). The upper end of the lever 158 extends into a chamber 167 within an. upper housing or cap 168 which is bolted or otherwise secured as at 169 to the top wall 170 of the carriage 50 (Figure 7). The upper housing 168 is provided with an access plate 171 covering the open end 172 of the chamber 167 and secured thereto as by the screws 173 (Figure 9). The upper housing 168 is also provided with a horizontal bore 174 within which is reciprocably mounted a contact rod or plunger 175 having a flange or head 176 opposite the end 177 engaging the roller 166. The head 176 is reciprocable within the bore 180 of a tubular extension 181 of the cap 168, which also contains a helical compression spring 182, one end of which engages the head 176 on the plunger 175 and the other end engages the head 183 on a pin 184 (Figure 9) which is received within a bore 185 in a plug 186 loosely and reciprocably received within the bore 180. The plug 186 is provided with a reduced diameter portion 187 received within a bore 188 of a cup-shaped member or thimble 189 and held therein by a screw 190 threaded into the threaded outer end of the bore 185. The cup-shaped member or thimble 189 is provided with an internallythreaded bore 191 which threadedly engages the correspondingly threaded outer end portion 192 of the tubular extension 181 of the upper housing 168. The external surface of the thimble 189 is knurled or otherwise roughened as at 193 to facilitate grasping by the fingers without slippage. As a consequence, when the thimble 189 is rotated in one direction or the other, it compresses or relaxes the compression spring 182, causing it to exert greater or lesser force upon the plunger 175, transmitting a greater or less resisting force through the lever 158 to the lap-rotating spindle 115 respectively.

Carriage feeding uni t The carriage feeding unit 14 which converts continuous rotation of the shaft 40 into intermittent step-by-step rotation of the screw shaft 61 (Figure l) in response to a demand therefor called forth by the lapping mechanism, is located at the rearward end of the machine on the right-hand side of Figures 1 and 2. The connections and power-transmitting functions of the

shafts

40 and 61 have been described above, up to the point where they enter and leave the carriage feeding unit 14 respectively.

The eccentric portion 48 (Figures 3 and 6) of the eccentric shaft 43 is encircled by the annular end portion 196 of a motion-transmitting link 197, the annular portion 196 being held in place upon the eccentric by a washer 198 retained in position by a cap screw 199 threaded into a bore 200 in the end of the eccentric shaft 43. As a consequence, rotary motion of the eccentric shaft 43 is thus converted into reciprocatory motion of the link 197, the opposite end of which is pivoted on the pivot pin 201 carried by the ears 202 extending laterally from the upper end portion 203 of a swinging arm 204, the lower end or hub 205 of which (Figure 5) is journaled upon the reduced diameter portion 67 of the screw shaft 6-1. Keyed or otherwise drivingly secured as at 206 to the reduced diameter rearward portion 67' of the screw shaft 61 is a ratchet wheel 207 retained in position by the nut 69 threaded upon the threaded end 68 of the screw shaft 61 (Figures 3 and 4).

The ratchet wheel 207 has peripheral ratchet teeth 208 which are intermittently engaged by the prong 209 on the end of a pawl 210, the central portion of which is pivotally' mounted on the pivot screw or stud 211 seated in the upper end portion 203 of the swinging arm 204. On the opposite side of the pivot stud 211 from the prong 209 (Figure 3), the pawl 210 carries a spring anchorage pin 212 to which is anchored the lower end of a tension spring 213, the upper end of which is similarly anchored to a spring anchorage pin 2'14 seated in the upper end portion 203 of the swinging arm 204. The tension spring 213, if not interfered with by certain pawl disabling mechanism, generally designated 215, urges the prong 209 of the pawl 210 downwardinto engagement with the ratchet teeth 208 of the ratchet wheel 207 so as to rotate the latter one tooth during each reciprocation of the link 197.

Since contsant step-by-step feeding motion of the screw shaft 61 is not desired, the pawl disabling mechanism 215 becomes operative to hold the pawl 210 out of operative engagement with the ratchet wheel 207 during a considerable portion of the time of operation of the machine. The opposite end of the pawl 210 from the prong 209 carries a pin 216 which passes into an elongated slot 217 in the enlargement 218 of a spring-urged plunger 219, the lower end 220 of which (Figure 5) engages the upper end 221 of an arcuate stop lever 222 which encircles the hub 205 of the swinging arm 204 and is pivoted thereto as at 223. Immediately above the pivot pin 223, the arcuate lever 222 is provided with a threaded bore 224 through which is threaded a stop screw 225 locked in position by a lock nut 226. The opposite end of the stop screw 225 engages a stop notch 227 in the swinging arm hub 205 to limit the swinging motion of the arcuate lever 222.

The upper end of the plunger 219 passes through a centrally-bored screw plug 230 threaded into the lower end of a bore 231 in the upstanding tubular extension 232 of the upper end portion 203 of the swinging arm 28-1- (Figure 3). The upper end of the plunger 209 carries a head 233 which is engaged by the lower end of a compression spring 234 mounted in the bore 231 and abutting the. upper end of the tubular extension 232 so as to constantly urge the plunger 219 downward and swing the arcuate lever 222 counterclockwise around its pivot 223. in its lowered position, the upper end of the slot 217 forces the pin 216 downward and consequently holds the prong 209 of the pawl 210 upward out of engagement with the ratchet wheel teeth 208 so as to impart no motion to the ratchet wheel 207. In order to provide guidance for the arcuate lever 222, the latter is seated in an arcuate groove 235 (Figure 4) encircling the lower side of the swinging arm hub 205.

The ratchet wheel 208 is provided with an eccentricallymounted handle 236 by which the screw shaft 61 may be rotated manually. In order to raise the plunger 219 so as to render ineffective the pawl disabling mechanism 215 and permit the pawl 210 to engage the ratchet wheel teeth 208 and rotate the ratchet wheel 207 in response to the reciprocation of the link 197 and consequent swinging of the arm 204, the carriage feeding unit 14 is provided with electrically-operated mechanism for swinging upwardly a lever 240 (Figures 3 to 5 inc), the right-hand end of which is pivoted to the pivot screw or stud 241 mounted upon a downwardly-extending bracket 242 secured by the screws 243 to the rearward end wall 17 of the base 15. Intermediate its opposite ends, the lever 240 is provided with ears 244 supporting an axle 245 which in turn rotatably supports a roller 246 which is movable upwardly into engagement with the arcuate lever 222 to lift the latter and the plunger 219 in response to an upward swinging of the lever 240.

The outer end of the lever 240 is pivoted as at the pivot pin 247 to a link 248, the upper end of which is pivoted to the pivot pin 249 carried by the armature 250 of an electromagnetic solenoid 251 mounted on an angle bracket 252 secured as by the screws 253 to the forward wall 18 of the base 15. The solenoid 251 is provided with the usual winding or coil 254 having

leads

255 and 256 connected to a conventional electrical energization control circuit (not shown) including certain limit switches described hereinafter and preferably also a relay for separating low-voltage control current from higher voltage solenoid-operating current.

In order to control the energization of the solenoid 251 and therefore to control whether or not the pawl 21% is located in or out of position to operate the ratchet wheel 207 and thereby rotate the feed screw 61 to advance the carriage 50 carrying the lapping mechanism, the upper housing 168 of the carriage 58 is provided with an upright switch mounting wall 26% (Figures 2, 3, 7 and The switch mounting wall 269 contains an elongated horizontal rib or boss 261 which projects forwardly from and is integral with the wall 264 which also contains an elongated horizontal guide groove 262 located in and parallel to the rib or boss 261. The latter is pro vided on its front face with a vertical switch mounting surface 263 (Figure 7) and the groove 262 is provided with spaced horizontally-elongated

holes

264 and 265 for receiving clamping

screws

266 and 267 respectively (Figure 10). The clamping screws 266 and 267 are threaded into threaded

bores

268 and 269 in

switch mounting blocks

270 and 271 respectively having

ribs

272 and 273 entering and slidably engaging the groove 262 in interfitting guiding relationship. Because of the elongated form of the

holes

264 and 265, the

screws

266 and 267 may be loosened and the switch mounting blocks. 270 and 271 slid horizontally along the horizontal boss or rib 261 so as to adjust their positions horizontally.

Secured as by the

screws

274 and 275 to the

switch mounting blocks

270 and 271 are

limit switches

276 and 277 respectively (Figure 10), preferably of the so-called micro-switch type, having operating

members

278 and 279 directed toward one another. A box-like cover 280 conceals and protects the

limit switches

276 and 277 and is held in position by screws 281 passing therethrough into the threaded holes 282 (Figures 2 and 7) in the switch mounting wall 260. The cover 280 carries an electrical conduit clamp 283 for receiving the end of an electrical conduit (not shown) carrying wires to the

limit switches

276 and 277.

In order to actuate the

limit switches

276 and 277, there is provided an actuating lever 290 having a rounded upper end portion 291 (Figure 2) engageable on its opposite sides with the switch-operating

members

273 and 279 respectively (Figure 10) but spaced apart from both

members

278 and 279 when the spindle 115, bell crank 138 and lever 290 are in their median positions, as determined by the cam 79 and shown in Figures 2, 6, 7 and 10. The central portion of the switch-operating lever 290 passes through an opening 292 in the top wall 170 of the carriage 50 and is pivotally mounted upon an axle or pivot pin 293 passing through its hub 294 (Figure 7) and secured in aligned

bores

295 and 296 respectively. The lower end of the switch-operating lever 290 extends downwardly into the recess 132 of the carriage bore 100 (Figures 6 and 7) and is bored as at 297 to receive a headed axle 29% upon which is mounted a roller 299 disposed between the spaced

annular flanges

130 and 131 so as to be engaged thereby in a similar manner as the roller 155 on the lever 158 previously mentioned (Figure 7). The limit switch 277 is a safety switch operating a relay (not shown) for halting the travel of the carriage 51 and preventing damage if the spindle 115 is pushed to the right beyond its normal limit of reciprocation by the cam 79, such as, for example, if the chuck 125 or lap L collides with some fixed object, such as the chuck 33 or head stock 20.

8 Operation Prior to operation of the lapping machine 10 of the present invention, a previously-bored workpiece W is mounted in the chuck 33 and clamped between its jaws 34, and the shank S of a corresponding lap L is mounted in the jaws 126 of the chuck 125. The tapers of the bore B and lap L are exaggerated in the drawings, for clearness of illustration. The position of the switch mounting block 272 and limit switch 276 is adjusted by means of the screw 266 in the slot 264 (Figure 10) until the operating member 278 of the switch 276 is operatively engaged by the upper end portion 291 of the lever 290 only when the lap L has ground its way to the desired depth into the bore B so as to correspondingly shift the spindle and consequently to shift the switch-operating lever 29%. The pulley 28 is then started in rotation from the motor (not shown), rotating the

parallel shafts

40 and 26 and consequently rotating the rotary lapping shaft 115 driven from the shaft 40 by the belt 92. The rotation of the shaft 40 also rotates the hollow shaft 78 and the cam 79 carried thereby (Figure 6) through the action of the key 81.

The rotation of the cam 79 causes the bell crank 139 to oscillate around its vertical pivot pin 140, causing the arm 137 and roller 134 carried thereby to rhythmically push against the forward surface 133 of the annular flange 130, thereby causing the lapping shaft 115 to reciprocate axially, it being returned to its forward position by the action of the helical compression spring 182 (Figure 9), acting through the plunger 175, lever 158 and

rollers

166 and 155. As a consequence, the lap L, while being rotated in its chuck by the shaft 115, is reciprocated axially into and out of the bore B in the work piece W every partial revolution of the lap L.

Meanwhile, abrasive lapping compound mixed with a suitable carrying liquid such as water, is caused to drip drop-by-drop onto the lap L from any suitable conventional container, so that on its rearward stroke, the lap L is provided with a film of lapping compound which is immediately carried into the bore B on its forward stroke. The in and out motion of the lap L consequently prevents drying out of the lap, insures proper and constant feeding of the lapping compound, and prevents sticking, freezing or jamming of the lap L in the bore B and consequently prevents damage or breakage of the lap L. The lapping action is carried out safely and eliiciently, even in the lapping of tapered bores, the lapping of which has previously occasioned great difiiculty and breakage of laps, as stated above.

The forward stroke of the lap L is limited by the eccentricity of the cam 79, halting when the roller 148 (Figure 6) on the bell crank arm 146 encounters the low or minimum radius point on the cam surface 150 (Figure 7), namely the point at the inner end of the ramp or inclined portion 151 thereof. Consequently, the lap L is prevented from jamming in the bore B, and, since the pulley 39 on the hollow cam shaft 78 is of smaller diameter than the pulley 93 on the lapping spindle or shaft 115, the lap L makes only a partial revolution while the cam 79 makes a complete revolution. As a consequence, the lap L engages the bore B throughout only a part of one revolution before it is retracted and a new film of lapping compound applied to the lap.

When the lap L has ground its way into the bore B sufiiciently far to cause the upper end 291 of the lever 290, which meanwhile is being swung to and fro by the oscillation of the lapping shaft 115, to engage and shift the operating member 278 of the limit switch 276 and actuate the latter to energize the winding 254 of the solenoid 251, preferably through the intermediate action of a relay (not shown), separating the low voltage control current from the high voltage power current. The energization of the solenoid winding 254 (Figures 3 and 5) in this manner causes its armature 250 to be pulled upward, thereby swinging the lever 240 and roller 245 upward. This action correspondingly swings the arcuate lever 222 upward around its pivot 223- (Figure pushing the vertical rod 219 upward and consequently lifting the upper end of the elongated slot 217 out of contact with the pin 216 on the rearward end of the pawl 210. This in turn permits the tension spring 213 to swing the pawl 21% clockwise around its pivot stud- 211, bringing the operating prong 2G9 thereof into close proximity to the ratchet teeth 2% of the ratchet wheel 207.

Meanwhile, the rotation of the eccentric 48 on the eccentric shaft by its connection to the shaft 40 (Figures 3 and 6) causes the link 197 to swing the vertical arm 2% to and fro, moving the pawl 210 back and forth. On its stroke to the right, the spring 213 yields to permit the pawl prong 2th to ride up the incline of a ratchet tooth 2% and drops in behind its radial shoulder, the tension spring 213 yielding to permit this rocking of the pawl Elli. On the rearward or leftward stroke, the pawl prong Z6? pulls the ratchet tooth 2% to the left, advancing the tooth 2-98 and rotating the ratchet wheel 237 and the screw shaft 61 upon which it is mounted. As a result, the carriage 59 is advanced through the engagement of its nut 58 with the threaded portion 60 of the screw shaft er.

The carriage continues to advance in this manner until the upper end 291 of the veritcal lever 22% oscillates out of engagement with the operating member 278 of the limit switch 276, opening the circuit of its relay (not shown) and consequently opening the energization circuit of the solenoid 251. With the winding. 254 of the latter de-energized, the armature 254 thereof drops (Figure 3), swinging the lever 241i and roller 256 downward. This action permits the arcuate lever 222 to swing downward around its pivot 223 (Figure 5), permitting the plunger or vertical rod 219 to move downward and causing the upper end of the elongated slot 217 to engage the pin 216 on the rearward end of the pawl 210 and rock the pawl 21d counterclockwise around its pivot stud Zll so as to swing its prong 289 out of engageability with the ratchet teeth 2% of the ratchet wheel 207. As a consequence, the carriage halts momentarily, until the lap L has again ground its way sufficiently far into the bore B to again actuate the micro-switch 276 and energize the solenoid winding to activate the carriage-feeding ratchet mechanism 14 and again advance the carriage 50 until the upper end 2% of the lever 2913 again swings out of engagement with the operating member 278 of the microswitch 2537, opening its circuit and again de-energizing the solenoid 251 as before.

This cycle of operations continues until the lap L completes the lapping of the bore B, whereupon the operator halts the machine it). He then retracts the lapping carriage 52' by rotatin the screw shaft 61 reversely with the aid of the handle 236, in order to replace the finished workpiece W with an unfinished workpiece and reposition the carriage St? at a proper starting point from which to advance, as before, during a new cycle of operations.

3. rat I claim is:

l. A lapping machine comprising a base, a workpiece holder rotatably mounted on said base, a lap holder rotatably mounted on said base with its axis of rotation disposed substantially coaxial with the axis of rotation of said workpiece holder, a carriage reciprocably mounted on said base for travel axially toward and away from one of said holders, one of said holders being mounted on said carriage for axial reciprocation relatively to the other holder and also relatively to said carriage, rotary powerdrivcn holder-rotating mechanism mounted on said base and drivingly and rotatingly connected to said holders, a power-driven holder oscillator drivingly connecting said holder-rotating mechanism to said reciprocable holder an responsive to the rotation of said holder-rotating mechanism to reciprocate said reciprocable holder relatively to said carriage, said oscillator being arranged to reciprocate said reciprocable holder periodically in timed relationship with a predetermined amount of rotation of 10, the other holder, and carriage-feeding mechanism respon sive to the travel of said' reciprocable holder a predetermined distance toward the other holder for advancing.

said carraige and said reciprocable holder bodily a predetermined distance toward said. other holder.

2. A lapping machine comprising a base, a workpiece holder rotatably mounted on said base, a lap holder rotatably mounted on said base with its axis of rotation disposed substantially coaxial with the axis of rotation of said workpiece holder, a carriage reciprocably mounted on said base for motion axially toward and away from one of said holders, one of said holders being mounted on said carriage for axialreciprocation. relatively to the other holder and to said carriage, rotary power-driven holderrotating mechanism mounted on said base and drivingly and rotatingly connected to said holders, a power-driven holder oscillator drivingly connecting said holder-rotating mechanism to said reciprocable holder and responsive to the rotation of said holder-rotating mechanism to reciprocate said reciprocable holder, and means including step-bystep feed mechanism operably connecting said holder-rotating mechanism to said carriage for advancing said carriage toward said other holder.

3. A lapping machine comprising a base, a workpiece holder rotatably mounted on said base, a lap holder rotatably mounted on said base with its axis of rotation disposed substantially coaxial with the axis of rotation of said workpiece holder, a carriage reciprocably mounted on said base for motion axially toward and away from one of said holders, one of said holders being mounted on said carriage for axial. reciprocation relatively to the other holder and to said carriage, rotary power-driven holderrotating mechanism mounted on said base and dri-vingly and rotatingly connected to said holders, a power-driven holder oscillator drivingly connecting said holder-rotating mechanism to said reciprocable holder and responsive to the rotation of said holder-rotating mechanism to reciprocate said reciprocable holder, and means including a screw shaft and nut thereon and step-by-step feed mechanism connected thereto operably connecting said holder-rotating mechanism to said carriage for advancing said carriage step-by-step toward said other holder.

4. A lapping machine comprising a base, a workpiece holder rotatably mounted on said base, a lap holder rotatably mounted on said base with its axis of rotation disposed substantially coaxial with the axis of rotation of said workpiece holder, a carriage reciprocably mounted on said base for motion axially toward and away from one of said holders, one of said holders being mounted on said carriage for axial reciprocation relatively to the other holder and to said carriage, rotary power-driven holder-rotating mechanism mounted on said base and drivingly and rotatingly connected to said holders, a powerdriven holder oscillator drivingly connecting said holderrotating mechanism to said reciprocable holder and responsive to the rotation of said holder-rotating mechanism to reciprocate said reciprocable holder, and means including a screw shaft and nut thereon and step-by-step pawl and ratchet feed mechanism operably connecting said holder-rotating mechanism to said carriage for advancing said carriage toward said other holder.

5. A lapping machine comprising a base, a workpiece holder rotatably mounted on said base, a lap holder rotatably mounted on said base with its axis of rotation disposed substantially coaxial with the axis of rotation of said workpiece holder, a carriage reciprocably mounted on said base for motion axially toward and away from one of said holders, one of said holders being mounted on said carriage for axial reciprocation relatively to the other holder and to said carriage, rotary power-driven holder-rotating mechanism mounted on said base and drivingly and rotatingly connected to said holders, a power-driven holder oscillator drivingly connecting said holder-rotating mechanism to said reciprocable holder and responsive to the rotation of said holder-rotating mechanism to reciprocate said reciprocable holder, and means operably connecting said holder-rotating mechanism to said carriage for advancing said carriage toward said other holder, and a carriage advancing means interrupter operatively connected to said carriage advancing means and responsive to a predetermined advance of said carriage for interrupting the power connection to said means.

6. A lapping machine comprising a base, a workpiece holder rotatably mounted on said base, a lap holder rotatably mounted on said base with its axis of rotation disposed substantially coaxial with the axis of rotation of said workpiece holder, a carriage reciprocably mounted on said base for motion axially toward and away from one of said holders, one of said holders being mounted on said carriage for axial reciprocation relatively to the other holder and to said carriage, rotary power-driven holderrotating mechanism mounted on said base and drivingly and rotatingly connected to said holders, a power-driven holder oscillator drivingly connecting said holder-rotating mechanism to said rcciprocable holder and responsive to the rotation of said holder-rotating mechanism to reciprocate said reciprocable holder, means including a screw shaft and nut thereon and step-by-step pawl and ratchet feed mechanism operably connecting said holder-rotating mechanism to said carriage for advancing said carriage toward said other holder, and a carriage advancing means interrupter connected to said pawl and ratchet feed mechanism and responsive to a predetermined advance of said carriage for holding said pawl out of engagement with said ratchet.

7. A lapping machine comprising a base, a workpiece holder rotatably mounted on said base, a lap holder rotatably mounted on said base with its axis of rotation disposed substantially coaxial with the axis of rotation of said workpiece holder, a carriage reciprocably mounted on said base for motion axially toward and away from one of said holders, one of said holders being mounted on said carriage for axial reciprocation relatively to the other holder and to said carriage, rotary power-driven holderrotating mechanism mounted on. said base and drivingly and rotatingly connected to said holders, a power-driven holder oscillator drivingly connecting said holder-rotating mechanism to said reciprocable holder and responsive to the rotation of said holder-rotating mechanism to reciprocate said reciprocable holder, means operably connecting said holder-rotating mechanism to said carriage for advancing said carriage toward said other holder, and a carriage advancing means interrupter including an electro-magnetically-controlled power-transmitting instrumentality operatively connected to said carriage advancing means and responsive to a predetermined advance of said carriage for interrupting the power connection to said means, and a circuit control element electrically connected to said instrumentality and responsive to the arrival of said axially-reciprocable holder at a predetermined location in its1 stroke for altering the energization of said instrumenta ity.

References Cited in the file of this patent UNITED STATES PATENTS 323,892 Wesson Aug. 4, 1885 883,649 Landis Mar. 31, 1908 1,011,478 Olsen Dec. 12, 1911 1,072,692 Bowers Sept. 9, 1913 2,350,023 Perrier May 30, 1944 2,388,610 Haneman Nov. 6, 1945 2,420,920 Van May 20, 1947 FOREIGN PATENTS 3,448 Great Britain Feb. 10, 1913