US2092876A - Grinding machine - Google Patents

Description

Sept. 14, 1937. R. H. CRAMER GRINDING MACHINE Filed March 1, 1955 4 Sheets-Sheet 1 won R QR mam 9 M E Z M a m V n T p 0 1H s w m 0 Sept. 14, 1937. R. H. CRAMER GRINDING MACHINE Filed March 1, 1955 4 Sheets-Sheet 2 4 Sheets-Sheet 3 Sept. 14, 1937. R. H. CRAMER GRINDING MACHINE 4 Filed March 1, 1935 P 1937- R. H. CRAMER 2,092,876

GRINDING MACHINE Filed March 1, 1935 .14 Sheets-Sheet 4 v 6 230 1 27 27a O 74 92 1 P 35 T S 178 21 /7 1\ 325 d" 298 9 96 E 272 266 270 268 6" INVENTOR. 262 00 RHYMOND H. cReMER,

Patented. Sept. 14, 1937 UNITED STATES PATENT OFFICE 2,092,816 GRINDING MACHINE Raymond H. Cramer, Newark, N. J., assignor to General Motors Corporation, Detroit, Mich a corporation of Delaware I Application March 1, 1935, Serial No. 8,906

24 Claims.

ling the approach and separation of a tool and a work piece. Another object is to provide improved mechanism for automatically compensating for wear of a tool such as a grinding wheel. Another object is to provide an internalgrinding machine having advantages in simplicity, cheapness, ease of setup and adjustment, and accurate and reliable control of work size and finish.

To these ends and also to improve generally upon mechanisms of this-character, the invention consists in the various matters hereinafter described and claimed. In its broader aspects, the invention is not necessarily limited to the specific construction selected. for illustrative purposes in the accompanying drawings in which Fig. 1 is a front elevation of the machine.

Fig. 2 is a right hand end elevation with parts broken away and in section.

Fig. 3 is a vertical sectional view through a portion of the cross feed mechanism.

Fig. 4 is a vertical sectional view taken at the rear of the cross feed slide and the associated spring abutment.

Fig. 5 is a plan view of the tool head with some parts broken away and in section. V

Fig. 6 is a sectional view on the line 6-6 of Fig. 5.

Fig. 7 is a vertical sectional view taken on the line 1-1 of Fig. 8. V

Fig. 8 is an end view of parts shown in Fig. 7 with a part of the pawl shield broken away.

Fig. 9 is a'rear elevation of the cross feed slide and associated parts.

Fig. 10 is a plan view of a valve.

Fig. 11 is a sectional view of the valve of Fig. 10. r

Fig. 12 is a diagram of the electrical and the fluid pressure connections.

A reference will first be made to general features of construction and operation. A work head and a tool head are mounted for relative movement in two directions, one of the heads reciprocating with a table and the other being on a bridge attached to the frame. One of the heads, preferably the tool head, is given a cross feeding movement controlled by a shiftable piston cam in a cylinder from one end of which fluid is allowed to leak out first through a coarse feed valve and, after a temporary stopping of the feed, through a fine feed valve. The 'feed is reliably controlled by work gauges and after completion of feed, the piston cam is reversed to quickly separate the work and the tool. The table has an amplified reciprocation for tool dressing controlled by one work gauge while another gauge controls a final 5 retreat which actuates a mechanism to compensate for tool wear and controls a work loading and ejecting mechanism besides restarting the next cycle so that the machine is fully automatic.

The numeral 2 indicates a main frame pro- 10' vided with ways fora reciprocating table 4 over which arches a stationary supporting bridge 6 for one of the heads. A bracket 8 on the table is connected to a piston rod Iii which is reciprocated by fluid in a cylinder l2. The work head 5 is preferably mounted on the bridge and the tool head, shown as having a grinding wheel for internal grinding, is mounted on the table to slide therewith and preferably also to have cross feeding movement. thereon. A support or base plate I4 is slottedat l6 to receive T-bolts l8 which clamp it to the table, the base plate being located by a key 20. An additional T -bolt 22 and screws 24 clamp a supporting plate 26 to the base plate H, the supporting plate being located by a key 28. 25 The rear end of the supporting plate is elevated as indicated at 30 and has. a groove to receive a tongue on a shiftable motor carrying plate 32. The plate 32 is tapped to receive four pairs of clamping screws 34 which pass through slots 36 9 in feet 38 carrying a motor 40. To shift the plate 32 and with it the motor, an adjusting- -screw 42 is threaded in a lug 44 of the supporting plate 26 and'is journalled for rotation without endwise movement in a block 46 attached to the 35 plate 32. This adjustment is to compensate for variations in the positions of certain parts which are driven by the motor but movable with respect to it. A pulley 48 on the motor shaft drives a belt 50 wrapped around a pulley on a grinding spindle 52, the belt being kept tight by a pulley 54 on an arm 56 which is pivoted on a bracket 58- and urged upwardly by a torsion spring 60. The grinding spindle with its grinding wheel G for grinding the bore of a work piece W is supported by a head 62 adiustably clamped by a plate 64 in a groove of a cross feed slide 66.

The cross feed slide 66 is slotted underneath to straddle upwardly projecting ways .66 on the support or base plate 14, the slideliying a long gib l0 and a. short gib I2 secu'r 'dj Y to it( by screws. A cylinder 14 is seen ;the front of the feed slide 66 by bolts "L the cylindef ing located by a tongue entering a groove at th put of the slide. The cylinder has heads 18 and '60 u with ports connected to flexible fluid supply pipes 82 and 84 respectively. The cylinder heads support adjustable abutment screws 86 and 88, the former tolimit the slow feeding movement of a piston 92 and the latter being arranged to enter a dash-pot recess 98 in the piston, the' piston having a quick movement towards the screw 88 and being finally cushioned. The piston has suitable piston rings near the ends but its central portion constitutes a shiftable cam having one or more inclines. In the illustrated construction there are two meeting conical cam surfaces 94 and 98 which are always urged against a cam follower or abutment 98. Both cam surfaces have a small degree of taper but the surface 94 tapers the more. Hence when the piston is moved slowly in a direction to approach the cylinder head 18,-

the cam surface 94 will first travel along the cam follower or abutment 98 producing a coarse feed and then the cam surface 96 will come into action to produce a fine feed. In the present invention, as will appear, coarse and fine feeds are further influenced and controlled by changing the speed of the piston at different portions of its stroke. Also the action of either cam can be prevented by limiting the stroke of the piston by the abutment screws. 'It should be understood that the cylinder and piston are a unit with the cross feed slide 66 and move therewith while the cam follower or abutment 98 is fixed during such feed but is moved a short distance intermittently between feeds to compensate for wheel wear.

The front end of the cam follower or abutment 98 is bevelled in three directions to. form an edge engaging the piston cam while the rear end is bevelled in one direction to flit against a cam or wedge I88 which is intermittently shiftable between the side walls or guides of a wedge-containing housing I82 having a transparent cover plate I84. The housing has a forward extension to better hold the cam follower or abutment 98 and is contained in a large chamber I86 of the cross feed slide, the chamber being closed at the top by a cover plate I88 and being large enough to permit the desired feed movement of the slide with respect to the housing. The housing I82 can be adjusted on the ways'88 but is normally anchored to the base plate I4 by a locking gib II8 (Fig. 6) fastened by screws II2. Fastened to the bottom of the housing I82 is a nut H6 in which is threaded an adjusting screw II8 whose front end is journalled for rotation in a plate I 22, nuts I28 and a collar preventing endwise movement. The plate I22 .is fastened to the front of the support or base plate I4 by screws. The adjusting screw II8 can be turned to procure an initial adjustment of the cross feed slide with respect to the housing I82, as during a setting-up for the character of work.

For producing the power which urges and moves the cross feed slide 66 rearwardly as such movement is permitted and controlled by translation of the piston cam, a strong coil spring I24 is seated around an annular projection I26 of the nut H6 and extends to a similar opposing abutment on a sleeve I 28. The sleeve forms a support at I38 for the plain rear end ofthe screw shaft H8 and is externally threaded in a nut I32 which is secured by screws I34 to the cross feed slide 66. The sleeve has wrench holes so that it can readily be turned to adjust the tension of the spring I24 and is locked in adjusted position by a lock nut I36. Since the cam follower or abutment 98 and the nut 6 are fixed in position on the base plate I4 during feeding, the coil spring I24 urges the cross feed slide 66 and its cylinder 14 rearwardly, the translation of the piston longitudinally gradually shifting cam portions of smaller diameter and of less inclination along the edge of the cam follower or abutment 98 and so providing one means for varying the feed.

Inasmuch as the grinding wheel continuously wears down to smaller diameter, a compensating mechanism provides for an intermittent but very small augmentation ofv the rearward stroke of the cross feed slide. This mechanism is actuated by the reciprocating table whenever the table retreats following the completion of a work piece. The mechanism effects this desired result by intermittently shifting the wedge I88 along the bevelled rear end of the cam follower or abutment 98. The wedge is drilled out to receive an internally threaded sleeve I42 having a flange fastened to the wedge by screws. An adjusting screw shaft I44 is threaded in the sleeve I42 and has a plain portion journalled for rotation without endwise movement in a cap I46 which is secured by screws to the housing I82. The cap has a tubular extension I48 projecting through an elongated slot in the slide 66 and abutting outer end of the screw shaft I44. The ratchet wheel has a tubular extension I52 abutting against a hand wheel I54 which is keyed on the screw shaft. A hub I56 is loosely journalled on the extension I52 and carries a long arm I58 and a short arm I68, the'two arms being angularly against a ratchet wheel I58 which is keyed on the spaced. The long arm pivotally supports a pawl I6I- arranged to engage the ratchet wheel for an intermittent and adjustable feed. The short arm is loosely pivoted to the upper end of a plunger I62 which is slidable in a vertical guide casing I84 on a bracket I66 which projects through a notch in the feed slide and is attached to the lower portion of the housing I82.

The plunger is urged downwardly by a coil spring I68 connecting a pin on the plunger with a pin projecting from the guide-casing I64. The

lower end of the plunger carries a cam roller I18 arranged to be actuated when it runs along an inclined cam I12 at the upper end of a bracket I14 fastened to the main frame. The cam is of considerable width from front to rear so that it remains in line with the cam roller in diiferent front-to-rear adjusted positions of the fixed housing I82. When the table retreats to the remote position-indicated in Fig. 1, the cam roller runs cap I46. The shield can thus be made to holdthe pawl I8I away from the ratchet wheel for more or less of the distance travelled by the pawl to adjust the compensationfor wheel wear. The hand wheel -I54 can be turned counterclockwise to manually restore the wedge to the in-position as when a new grinding wheel is substituted for a worn one and it also can be used at anytime to retract the cross feed slide.

The work head may be of any suitable type which is preferably loaded and unloaded autodischarge a completed work-piece from the wheels and to lower the new piece to grinding position. The pressure idler and ejector are actuated s1.- multaneously by arms connected to a rock shaft 200' journalled on a head casting 202. The shaft is rocked by a plunger 204 having a cam roller 205 engaging a cam 206 fastened to the top of the reciprocating table 4. The cam comes into action when the table retreats so that ejection and loading occur when the wedge I00 is given its feed compensating motion above described. Control of sizeis preferably accomplished by concentric gauge plugs 208 and H0 carried by a gauge rod 2|2 shiftable endwise in a guide casing 2l4 adiustable on the work head. The gauge rod is connected by a bracket 2|6 to a guide rod 2H and to a control rod 2l8 having a pair of contacts for successively completing electric circuits hereinafter referred to. As will appear, one contact controls an amplified reciprocation of the table to carry the grinding wheel past a fixed dressing diamond 220 carried by a bracket attached to the frame and the other contact controls the more remote retreat of the table for loading and unloading. These gauge contacts also control the operations of certain valves as will appear.

Referring to the diagram of Fig. 12 and also to Figs. 10 and 11, pressure fluid from a pump comes through a pipe 222 to a valve casing 224, the fiuidentering an annular passage 226 between collars on a slidable reversing valve 228 and going through the flexible pipe 84 to that end of the cylinder 14 which is nearest to the cam surface 86. Exhaust fluid from the other end of the cylinder goes through the flexible pipe 82 to a pipe 230 connecting the valve casing 224 with a feed control valve casing 232. That branch of the pipe 230 which goes to the valve casing 232 leads to a normally open shut-oil" valve 234 having a control handle 236 at its upper end and a coil spring 238 engaging the opposite end to keep a tight joint between a collar 239 on the valve and the casing cover. From the shut-01f valve, there are branch ports 240 leading to two similar, angularly adjustable escape or feed valves 242 and 243. The valve 242 is .the coarse feed valve and is shown in detail in Fig. 11. It comprises a stem having a reduced portion with a cam-like shoulder 244 which restricts the leakage of fluid in accordance .with the rotary adjustment controlled by a dial 246 fastened to the upper end of the stem. The dial has a circular groove containing a stop pin 248v arranged to engage a stop pin 250 projecting into the groove from the valve casing, thus to limit turning of the valve. A ball 252 is interposed between a conical seat in the valve casing and a seat on a spring pressed plunger 254 inserted in the lower end of the valve stem. This makes for easy turning of the valve and keeps a collar 25 5 on the valve against the casing cover. The valve discharges fluid to an escape port 256 leading to an annular passage 258 between collars on a shiftable selector valve 260, the fluid then going out through a pipe 262 to the valve casing 224. The selector valve is shown in a position to allow leakage through the coarse feed valve 242 to its escape port 256 while a more restricted escape port 264 from the flne feed valve 243 is blocked oil by the valve 260 until the latter is subsequently shifted to block off the port .256. The relative amounts of leakage through these ports can be varied by turning the dials and provides a very sensitive control offeed. Fluid discharging pasteither of the feed valves 242 or 243 to the pipe 262 enters an annular passage 286 between collars on a slide valve 268 and normally passes to a tank through an exhaust port 210.

A source of electric power is connected to a pair of supply wires by a switch 212, one wire leading to a pair of movable contacts 214 and 216. These contacts correspond to the two gauge plugs and they successively complete electric circuits by engaging fixed contacts 218 and 280 respectively. A wire from the contact 218 leads to a magnet 282 and a wire from the contact 280 leads to a magnet 284. A wire from the magnet 284 leads directly back to the main line but the other wire from the first magnet 282 leads first to a switch 286 which is urged to open position by a coil spring 288. This switch is however kept closed during coarse feed by an arm 290 on a pivoted selector lever 292 which has a connection at 294 with the selector valve 260. When the contacts 214 and 218 come together, the magnet 282 is energized and attracts an armature 296 on a pivoted lever having a long arm 298 connected at 300 to'the slide valve 268. The resultant swinging of the lever counterclockwise shifts the valve 268 to the right and blocks ofi the pipe 262, thus temporarily stopping the feed entirely. During this stopping of feed, the table is given its amplified reciprocation for wheel dressing controlled by a lever arm 302 connected by a coil spring 304 to the'frame. The arm 302 (see Fig. 1) lifts a latch 306 to release a dog-carrying plate 308 for sliding movement with respect to the table. A pivoted dog 3"] on the plate is spaced from a dog 3l2 fixed on the table and these dogs control the normal grinding reciprocation of the lever 3l3. Upon the unlatching of the plate 308 however, the dog 3I0 is not effective to reverse the table for the in-stroke until the table comes out far enough for a plate 314 fixed to the table to engage the plate 308. As the table thus makes its amplified out-stroke, a pivoted dog 3|6 on the table engages a lug M8 on the selector lever 282 and swings the lever clockwise. The selector valve 260 is thus shifted inwardly blocking oif the escape port 256 from the coarse feed valve 242 and opening the escape port 264 from the fine feed valve 243. Leakage from the cam cylinder and its pipe 82 then occurs at a slower rate and the piston cam moves more slowly and produces a slower feed. It will be understood that the aforesaid opening of the switch 286 deenergizes the magnet 282 so that the coil spring 304 will swing the lever 298 clockwise and shift the valve 268 inwardly to its original position to permit the pipe 262 to discharge again 'to the exhaust port 210.

The normal grinding reciprocation of the table is continued until the second gauge contacts 216 and 280 come together and energize the second magnet 284. This magnet attracts an armature- 322 on a lever having a long" arm 324 connected to-theslidable reversing valve 228. The valve is shifted outwardly to the right to place the pressure fluid from pipe 222 in communication with This directs pressure fluid 'to the pipe 82 and table by alternately engaging asuitable reversing an annular passage 325 leading to the pipe 230.

quickly reverses the piston cam while exhaust fluid from the other end of the cylinder occurs freely through the pipe 84 to the passage 226 and thence to a short port communicating with the exhaust port 210. It is to be observed that, although the pressure fluid in pipe 230 also has access to the feed valve casing 232 during this reversal of the piston, the leakage of fluid through the fine feed valve 243 is not extensive enough to interfere with such reversal. Reversal of the piston cam of course backs the grinding wheel positively away from the finished work. The table then retreats, an arm 326 on the lever 324 being connected by a coil spring 328 to the frame and operating to lift the pivoted dog 3! so that the latter rides freely over the reversing lever 3l3. As the table thus reaches its remote position, the cam roller I10 rides up on the cam I12 and produces the hereinbefore described feed compensation for wheel wear. The finished work is meanwhile ejected from the work head and a new piece loaded on it. The table does not stop in the retracted position but immediately returns, this reversal of movement being effected by a table dog 330 which engages the reversing lever 3l3. As the table returns, a pivoted table dog 332 engages an oflfsetlug 334 on the selector lever 292 and swings it counterclockwise to the original position with the switch 286 closed and the selector valve open to the coarse feed valve. The return of the table retracts the gauges and so opens the magnetic circuits to make ready for the next cycle.

I claim: g

1. In a machine of the character described, a support, a feed slide movable with respect to the support, a feed cam slidably carried by one of said members and a cam follower carried by the other, a piston and cylinder unit for causing relative shifting ovement between the cam and the follower to .control movement of the feed slide, and means including a valve to decrease the speed of'shifting for causing the feeding effect of the cam to change during such relative shifting; substantially as described.

2. In a machine of the character described, a

support, a feed slide movable with respect to the.

support, a feed cam carried by one of said members and a cam follower carried by the other, a piston and cylinder unit for causing relative shifting movement between the cam and the follower to'control movement of the feed slide, means including a valve for causing the feeding effect of the cam to change during said relative shifting, and a work gauge controlling the last named mea substantially as described' 3. Ina m hine of the character described, a support, a feed slide movable with respect to the support, a cylinder and piston unit carried by one of said members and having a com, a 'camfollower carried by the other member, and means for controlling the speed of the cam by throttling the escape of fluid from the exhaust side of the cylinder; substantially as described.

4. In a machine of the character described, a support, a feed slide movable with respect to the support, a cylinder and piston unit carried by one of said members and having a. cam adapted to control the feed movement of the slide, a valve casing having an escape port communicating with the exhaust end of the cylinder, and a slide valve shiftable toclose or open the escape port; substantially as described.

5. In a machine of the character described, a support, a feed slide movable with respect to the support, a cylinder and piston unit carried by one of said members and having means adapted to control the feed movement of the slide, a valve casing having an escape port communicating with the exhaust end of the cylinder, a slide valve shiftable to close or open the escape port, and a reciprocating table having means to effect shifting of the slide valve; substantially as described.

6. In a machine of the character described, a support, a feed slide movable with respect'to the support, a cylinder and piston unit carried by one of said members and having means adapted to control the feed movement of the slide, a valve casing having a plurality of escape ports spaced apart and communicating with the exhaust end of the cylinder, a selector valve shiftable to block off one part and open the other for making the escape ports effective in sequence, and a slide valve shiftable in one direction to momentarily prevent discharge from the open escape port to stop the feed slide, and said slide valve being shiftable in the opposite direction to provide for resumption of feeding movement under control of said open escape port; substantially as described.

7. In a machine of the character described, a support, a feed slide movable with respect to the support, a cylinder and piston unit carried by one of said members and having means adapted to control the feed movement of the slide, a valve casing having a plurality of escape ports communicating with one end of the cylinder, a selector valve for making the escape ports effective in sequence, and a work gauge controlling the shifting of the selector valve; substantially as described.

8. In a machine of the character described, a support, a feedslide movable with respect to the support, a cylinder and piston unit carried by one of said members and having means adapted to control the feed movement of the slide, a valve casing having .a plurality of escape ports communicating with one end of the cylinder, a selector valve forv making the escape ports efiective 'in sequence, a reciprocating table having means to cause shifting of the selector valve, and a work gauge controlling a table movement for such shifting of the valve; substantially as described.

9. In a machine of the character described, a support, a feed slide movable with respect to the support, a cylinder and piston unit carried by one of said members and havingmeans adapted to control the feed movement of the slide, a valve casing having a plurality of escape ports communicating with one end ofthe cylinder, a selector valve shiftable from one escape port to the other for making the escape ports effective in sequence, and means for causing a temporary stopping of the escape ports when said selector valve is shifted; substantially as described.

10. In a machine of the character described, a

support, a feed slide movable with respect to the support, a cylinder and piston unit carried by 1 one of said members and having means adapted to control the feed movement of the slide, a valve casing having a plurality of escape ports communicating with one end of the cylinder, a selector valve for making the escape ports effective in sequence, a valve for causing a temporary stopping of the escape ports, and a work gauge controlling the shifting of the last-mentioned valve and the selector valve; substantially as described.

11. In a machine of the character described,

a support, a feed slide movable with respect to the support, a feed cam carried by one of said members and a cam follower carried by the other, a work head and a tool head, one of said heads being movable with the slide, means for causing relative shifting movement between the cam and the follower to control the feed slide, and a. shiftable wedge for controlling an intermittent adjustment of the feed slide to compensate for tool wear; substantially as described.

12. In a machine of the character described, a

support, a feed slide movable with respect to the support, a feed cam carried by one of said members and a cam follower carried by the other, a

work head and a tool head, one of said heads nnsupport, a work head and a tool head, one of said heads being movable withthe slide, a cam, means for shifting the cam with respect to the slide, a cam follower engaging the cam, a wedge engaging the follower, an adjusting screw having threaded connection with the wedge, the cam and the adjusting screw being mounted one on the slide and one on the support and means for turning the screw; substantially as described.

18. In a machine of the character described, a'

support, a feed slide movable with respectto the support, a work head and a tool head, one of said heads being movable with the slide, a cam shiftable on the slide, means for shifting the cam with between one of said piping connections and the ing connections with opposite ends of the cylinder, exhaust line to control a slow feed of the slide, an exhaust line, an escape valve having a pair of a sliding carriage supporting one of the heads to throttling ports of different throttling eflect, cause relative traversing movement between the each being in communication with and interposed 5 tool and the work, and a valve shiftable by a. between one of said piping connections and the 5 movement 01. the carriage to prevent escape of exhaust line, a selector valve in communication iluid from the throttling port; substantially as with the throttling ports and shiftable from one described. to the other to make the ports efiective in sequence 24. In a machine 01' the character described, to change the character of the feed, and a valve 10 a work head, a tool head, a feed slide supporting shiftable to prevent escape of fluid from either 10 one of the heads, a cylinder and piston unit, for of the throttling ports; substantially as described. actuating the slide, a reversing valve having pip- RAYMOND H. CRAMER.

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