US2585533A - Internal grinding machine with automatic air gauge sizing - Google Patents

Description

Feb. 12, 1952 W. J. BRYANT ET AL INTERNAL GRINDING MACHINE WITH AUTOMATIC AIR GAUGE SIZING Filed May 29, 1948 1% 1m m 9, w 23/? 4 Sheets-Sheet 1 Feb. 12, 1952 w. J. BRYANT ET AL INTERNAL GRINDING MACHINE WITH AUTOMATIC AIR GAUGE SIZING Filed May 29, 1948 4 Sheets-$heet 2 Feb. 12, 1952 w. J. BRYANT ET AL INTERNAL GRINDING MACHINE WITH AUTOMATIC AIR GAUGE SIZING Filed May 29, 1948 4 Sheets-Sheet 3 fi m/22 1952 w; .1. BRYANT ET AL INTERNAL GRINDING MACHINE WITH AUTOMATIC AIR GAUGE SIZING Filed May 29, 1948 4 Sheets-Sheet 4 3 m u 2% Jw Q 2% W7. w

Patented Feb. 12, 1952 INTERNAL GRINDING MACHINE WITH AUTOMATIC AIR GAUGE SIZING William J. Bryant, Thor H. Ljunggren, and Willis F. Moore, Springfield, Vt., assignors to Bryant Chucking Grinder Company, Springfield, Vt., a corporation of Vermont Application May 29, 1948, Serial No. 29,996

4 Claims.

This invention relates to internal grinding machines with automatic sizing mechanism, and has for an object to provide such a machine where in the final size control is produced by an air gage sizing mechanism, such a mechanism being capable of extremely high accuracy.

A further object is to embody the air gage in a plug gage mechanism which is periodically presented to the work during the finish grinding operation.

Still another object is to provide a plug air mechanism so constructed as to avoid violent indicator fluctuations with consequent liability to damage during the operation of the machine.

A further object is to provide mechanism by which the grinding operation is stopped the wheel is retracted from the work as soon as the gage indicator shows that the desired finish hole size has been reached.

A further object is to provide for an automatic cycle of machine operations, the last of which comprises a finish grinding operation which is terminated automatically when the desired finished size as determined by the air gage been reached.

Further objects and advantages will appear from the following description of an embodiment of the invention shown in the accompanying drawings in which Figure l is a front elevation of an internal grinding machine.

Figure 2 is a fragmentary vertical sectional. view through the work spindle and the work wheel carriage to a larger scale than Figure l and showing the carriage mounting and the gage stem and its actuating parts, the gage stem being shown as extended within the hole in the work.

Figures 3, 4 and 5 are detail sectional views to a larger scale showing successive rel: in between a work piece, a grinding wheel, air gage stern and related parts as the gr, and traverse of the work by the grinding wheel progresses, Figure 5 showing the parts after the hole has been ground to a size which permits the gage stem to enter it.

Figure 6 is a detail sectional view on line of Figure 1,

Figure 7 is a diagrammatic sectional view of the air gage mechanism.

Figure 8 is a detail sectional view on line i 3 chine illustrating the cycle control mechanism for gage controlled finish grinding, and either gage controlled or diamond sizing for rough grinding, the mechanism being set for gage controlled rough grinding.

Referring to the drawings, at l is indicated a machine base on which is mounted a traversing carriage 2 which supports a wheel head 3 carrying a grinding wheel spindle 4 upon the outer end of which is mounted a grinding wheel 5. The head 3 is mounted on the carriage 2 for adjustment backwardly and forwardly, being supported on ways I in which it is held by a retaining strip 8 (see Figure 2) held against a foot of the wheel head, as by screws 9. The traversing carriage 2 carries a bar l0 extending in the direction of traverse, and the opposite ends of this bar are formed hollow as at H (see Figures 2 and 10), thereby providing hydraulic cylinders, within which extend plungers 12 having passages l3 therethrough with which communicate fluid pressure pipes l4 and 15. The plungers i2 are secured in caps 16, which, in turn, are secured to the bed I as by screws 11.

The bed is also provided with transverse 'ways l8 on which is mounted a transversely movable carriage l9 provided with ways 29 for the recep tion of a work head 2!. The carriage It is shown as supported on rollers 22 and is guided along a guide strip 23 against opposite edges of which bear guide rollers 24 and 25. The specific mounting of this carriage l9 forms no part of the present invention, that shown being subject matter of Ljunggren application for patent Serial No. 680,502, filed June 29, 1946, for Carriage Mount- The work head 2! has journaled in bearings 28 a work spindle 29 having at its forward end a standard spindle nose 3i) and at its rear end a driving pulley 55 by which the spindle may be rotated is keyed. To this nose is shown secured by bolts 3|, a work-holding chuck 32 having a plurality of pivoted jaws 33 arranged in circular series about its axis and having fingers 34 at its forward end which engage the forward face of a work piece W and hold it pressed back against stop pins 35 suitably carried by the chuck 32. This chuck per so also for-ms no part of the present invention, forming subject matter of the Ljunggren and Green Letters Patent No. 2,423,380, granted June 14, 1949, for Combination Diaphragm and Clamp Chuck. The jaws 33 are pivoted to a circular flange extending outwardly from a sleeve M which is threaded to an actuating sleeve 42. By exerting forward axial motion on the sleeve 42, the jaws 33 may be moved forwardly relative to the body of the chuck 32 to a point where they ride out from beneath a cam ring 43 so that springs 44 acting on the rear ends of the jaws 33 rock the jaws outwardly, freeing the work piece therefrom. The rear end of the sleeve 42 has journaled nonslidably thereon a ring 53 which is connected through a pin and slot connection at with a lever 52 by the rocking of which the desired axial motion of the sleeve 42 may be effected, this sleeve 42 rotating with the spindle, being keyed thereto as at 53.

Slidable within the sleeve 42 is a tube 60, this tube constituting the stem of an air gage. At its forward end, as shown best on Figures 3, 4 and 5, it has a reduced diameter threaded portion 6| with which is engaged a work feeler head 62. This feeler head 52 has an enlarged diameter outer end portion 63 through which extends a plurality of radial passages 64 opening out from the periphery of the portion 63. The inner ends of these passages 84 lead from a chamber 65 opening to the interior of the tube 60. The feeler head 62 is of such an external diameter with respect to the desired finished size of the work that when it is engaged within the hole in the work, as shown in Figure 5, it permits discharge of air from the passages 64 past the head 63 and out from the hole in the work at a rate such that the air gage indicator will show the work to be of the desired finished size.

When the head 52 is out of the work, it is normally housed within a bored portion of a sleeve H through which the stem is slidable and which, in turn, is slidable axially within the sleeve M. The counterbored hole 10 is of a size which receives the head 62, but is not the same as the desired finished size of the hole in the work so that the air gage indicator does not register correct hole size when the head 62 is within this counterbored portion.

A size gage of this general type is shown somewhat diagrammatically in Figure 7. The stem 56 is slidable at its rear end within a gland 15 from which it receives air under pressure from a pipe l6. This pipe 16 leads from the upper end of an indicator tube 11, the bore of which is tapered lengthwise, the amount of taper being much exaggerated in the drawings, the upper end of the tube Ti being of the larger diameter.

The lower end of the tube 11 is connected through a pipe 18 with a reducing pressure valve 19 which receives compressed air from any suitable source through a pipe and an air filter 8|.

Within the indicator tube 1! there is an indicator bob 82 which floats in the air column and the height within this air column at which it rests is determined by the differences in pressure above and beneath it, which in turn, are determined by the freedom with which the air discharges throug the passages 64, this, in turn, being responsive to the size of the hole in which. the head 63 is positioned at any time. A very little difference in diameter of this hole causes a substantial change in the height position of the bob 82 within the indicator tube 11, thus giving 7 a much magnified indication of hole size differences. A spring bumper 85 at the upper end of this tube takes the impact therefrom in case of a sudden drop in pressure in the pipe 16 which would cause the bob 82 to be blown violently upwardly. However, it is undesirable to permit too sudden fluctuations as the bob might be damaged thereby, and for this reason the sleeve ll has been provided so that until iii) such time as the hole in the work piece W has been ground to sufficient size to permit the entry of the head 63 thereinto, it remains housed within the counterbored portion 2'0 of the sleeve "H, and when retracted from the hole it passes directly into this counterbored portion. This causes the bob 82 to remain suspended in the indicator tube ll, but when the head is in the sleeve, at a position different from that indicating correct hole size.

During at least the finish grinding portion of the machine cycle, the air gage is in operative condition so that as soon as correct finished size is reached, the gage will so indicate it and automatically separate the wheel from the work and stop the machine cycle. During this finish grinding, the stem Si is periodically moved toward and from the work piece in time with the reciprocation of the grinding wheel, being moved toward the Work as the grinding wheel is retracted and being retracted the grinding wheel is being projected so as to be out of the way of the grinding wheel when it extends through the work hole,

as in the position shown in Figure 3. The mechanism for so actuating the stem 60 is best illustrated in Figure 2. This stem 60, as well as all the other parts carried by the work spindle 29, rotates with the work spindle. The rear end portion of the stem 60 is journaled in bearings 98 in a casing 91 which is held against rotation, and to this casing 91 is slidably and pivotally connected the upper arm of a bell crank lever 92 fulcrumed on the shaft 53. The other arm 94 of this bell crank lever is connected through a link 95 to the upper end of a rod 96 guided for vertical motion through a bracket 91 secured to a fixed casing member 58 carried by the work head 2|. The lower end of the rod 96 is provided with a head 95 which is engaged by an actuating rod I00 carried by one arm of a bell crank lever l0! and extended in the direction of motion of the carriage l5 so that the head 99 may bear thereon in all positions of the carriage l9. This bell crank lever is journaled on the pivot I02 carried by a bracket I03 secured to the bed I. Another arm Hi4 of this bell crank lever IUI engages in the peripheral groove of a spool "15 carried by a rod N2, the inner end of which is in position to be struck by the end of the bar in when this bar approaches that end of its stroke in which the grinding wheel 5 extends furthest through the work (Figure 3), so that as the wheel moves to this extreme position, the rod is moved to the left, rocking the bell crank lever IZH in a direction to lift the bar 85, which rocks the bell crank lever 94 in a direction to retract the stem 50 out of the way of the grinding wheel. The head 62 of this stem engaging the base of the counterbored portions 73 of the sleeve ll also retracts the sleeve 7'! out of contact with the work face against the action of the coil spring IIU which reacts between a head Hi of the sleeve TI and a diaphragm portion H2 of the chuck 32. As the wheel is withdrawn by reverse motion of the bar 19, the rod H26 may follow it as far as permitted by a piston portion 25 thereon, riding to the end of a hydraulic cylinder I21, this piston :20 being carried by a sleeve I22 supporting and guiding the rod I03. This allows the rod 96 to drop and allows the spring 1 H] to press the sleeve ii against the work piece as shown in Figure 4, and if the hole in the work is of sufficient size, allows the stem to move still further in the same direction to project the head 6'2 into the work, as shown in Figure 5. When the stem is in accuses the work as shown in Figure 5. the position of the bob 82 of the air gage indicates the size of the hole and when this position is at the point corresponding to the desired hole size, the grinding is terminated in a manner which will later appear.

The mechanism for determining the cycle of operations of this machine, including "the control of the final finish grinding operation by the an" gage is a modification of that which forms subject matter in the application for patent by Thor H. Ljunggren filed October 5, 1946, Serial No. 701,443 for Internal Grinding Machine which issued as Patent No. 2,502,862 on April 4, 1950. The mechanism for producing the relative feed between the work and the grinding wheel as illustrated herein is the same as that for this Ljunggren application and is shown best in Figures 6, 8, and 9.

The carriage I9 which supports the work hold or is provided with a bracket I30 depending from its forward face and secured to the forward face of the carriage as by screws, one of which is shown at l3I in Figure 6. Journaled in this bracket is the forward end portion of a feed screw I32. This feed screw is threaded through a circular nut I33 which is journaled inan upwardly extending flange I34 of the frame I. It is held against axial movement within a bushing I35 in this frame, and for this purpose it is provided with a circular end flange I36 between which and the bushing I35, a collar I31 is interposed, the inner end of the nut I33 being externally threaded for the reception of a nut I36 which may bear against a washer I39 interposed between it and the flange 134 and the bushing I35. The flange I36 is seated and secured in a socket in a gear I40 and by rotation of this gear I40 it is evident that the lead screw I32 may be moved axially without its rotation, imparting corresponding motion to the carriage I9 and the work holder. Such rotation is made use of to effect the normal feed motion between the grinding wheel and the work as will later appear.

It is also evident that axial motion of the carriage may be produced by rotation of the feed screw I32 while the nut I33 is stationary; .Such action is employed in accordance, with thepresent construction for producing a slight feed mot-ion of the carriage I9 in addition to that produced by rotation of the nut I33 to compensate for reduction of wheel size due to wear and truing. To this end, the outer end of the feed. screw I32 has keyed thereto the hub I42 of a hand wheel I43,

and secured to this hub is an annular worm gear I44 with which meshes a worm I45 fixed to a shaft I46. As shown in Figure 1, this shaft I46 has a knob I41 on one end which can be turned by the operator, and it is connected at its other end to a gear I40 which may be engaged by a vertical rack bar I49 carried at theupper end of a plunger I56 (see also Figure of a hydraulic cylinder I59. This rack bar is normally held elevated as by a spring, but may be depressed against this spring, thus to turn the gear I46 when hydraulic fluid is introduced aboveit, as through a pipe I4I. A suitable ratchet mechanism (not shown) is interposed. between the gear I48 and the shaft I46 so that. the lifting of the plunger I58 is ineffective to turn the shaft I46.

The gear I40 is rotated in order to produce the normal feed and retracting motions of the work carriage I9 by the rotation of a. gear I50. meshing therewith, this gear being carried by a hub member I5I which also carries a gear portion I52 with which meshes a rack bar I53. This rack bar I53, as shown diagrammatically in Figure 10, forms the piston rod for an hydraulic piston I54 riding in a hydraulic cylinder I55. When fluid pressure is introduced to the right hand end of this cylinder I55 as through the pipe I56, the gear I is rotated in a direction to feed the work relative to the wheel, while when it is moved in the reverse direction by fluid pressure introduced into the left hand end of the cylinder I through the pipe I51, the work is retracted relative to the wheel.

Means are provided by which, after the feed has been started and the work and grinding wheel fed toward each other from fully retracted position at relatively high speed to a point slightly before the wheel and work contact, the feed motion is slowed, and provision is made by which this slowing and the point at which it begins is independently adjustable during rough and finish grinding. This mechanism is shown best in Figures 8 and 9, and diagrammatically on Figure 10. The gear hub I5I has a forward extension I terminating in a reduced diameter portion I6I.

Journaled on this portion I6I are a pair of arms I62 and I63 and keyed to the outer end of the extension I6I is a disk I64. This disk I64 is provided with a pair of arcuate slots I65 and I66, and the arms I62 and I63 have threaded thereinto the extremities of thumb screws I61 and I68 which extend through the slots I65 and I66, respectively, and by the tightening of which the arms I 62 and 63 may be clamped in limited angular adjustment positions to the disk I64 and be. caused to rock with the hub extension I60. Each of these arms I62 and I63 has secured to its rear face a rearwardly extending segmental arm I10 and HI, and each of these arms I10 and HI is formed with a thin forward edge which may ride behind a corresponding switch-actuating roll I12 and I13. When these arms I10 or I1i engage the switch-actuating rolls I12 or I13, they close switches, which, as will later appear, interpose slowing mechanism in the feed controls,

.so that the speed of feed is reduced and independently for rough and finish grinding until such time as the feed motion is terminated. For the sake of clarity in the diagram (Figure 10), the elements I10 and HI are not shown as arranged about the axis of the gear I50, but instead are shown as arranged about a second shaft in geared relation to the. gear I50. Either arrangement, of course, may be employed.

With the mechanism herein shown, the feed is terminated for the finish grinding by the action of the air gage. For the rough grinding it may be terminated selectively either by the impingement of an extension of the piston. rod I53 (see Figure 10) on a stop I15 carried by an axially movable bar I16, this being by diamond sizing, or it may be done by the action of the air gage. In the diagram of Figure 10 the parts are selectively adjusted for the control of both rough and finish grinding by the action of the gage. The bar I16 is normally pressed, as by a spring I11, into axial position to bring the stop I15 into alinement with the piston rod. I53, and when in such a-llnement and when struck by the piston I53 and pressed axially, it closes a switch at I18 which acts to terminate the rough grinding. During finish grinding this bar I16 is placed in the position shown, by the introduction of hydraulic pressure beneath its lower end, so that the stop I15 is. in inoperative position.

As hereinabove noted, the wheel supporting 7 carriage 2 is reciprocated by hydraulic means, this including the hydraulic cylinders formed in the end portions of the bar !0. This reciprocation is controlled by means shown somewhat diagrammatically in Figure 10. riage 2 are a series of depending dogs 260, 20!, and 202. The dog 202 depends further than the others. The dog 250 is intermediate and the dog 20! is the shortest, and as the wheel carriage is reciprocated these dogs at the end of certain strokes act upon a follower roll 203 eccentrically carried by the upper end of a control element 204. This control element is rockably mounted and may take three different vertical positions. As shown it is in the highest of these positions where it is contacted on the inner end of its stroke by the dog 202 and on the outer end of its stroke b the dog 20!. Such contact causes rocking of the member 204 and this is transmitted through a long gear 205 thereon and through a rack 206 to a reversing valve 201. This reversing valve has a pair of pressure lines 208 and 209' leading from a common line 2H2, deriving pressure from a pump 2!! drawing a supply from a suitable tank 2! 2. The pressure delivered by this pump is controlled by a pressure relief valve 2l3 which discharges back to the tank 2! 2. In the position shown the valve 20'! opens communication through the pipe 203 past the valve and the pipe to the right hand cylinder 2!6, thus to drive the carriage 2 to the left, While the discharge takes place from the left hand cylinder through the pipe !4 past the valve 207, through the pipe 220, a valve chamber 22!, past a cannelure 222 of this valve chamber 22!, pipe 223, pipe 224 containing an adjustable throttle valve 225, pipe 226, and back to the tank 2!2. Also discharge may take place from the pipe 223 through the valve chamber 22'! around a cannelure 228 of the valve 229, pipe 230 and throttle valve 23! to the pipe 226. The valves 225 and 23! are thus in parallel and the discharge from these two valves governs the traverse speed of bar !0 during the grinding phase of the work cycle and with valve 220 in lifted upper position shutting off pipe 230 from pipe 223, the lesser discharge through valve 225 governs the lesser speed of bar !0 during the dressing phase of the work cycle. When the traverse carriage 2 on the bar !0 reaches the point Where the wheel is about to engage the work, a shoe 235 on the carriage engages and closes a switch 236, which closes a circuit from a lead 231 to leads 238 and 239 through a solenoid 245] to ground. Energization of this solenoid 243 lifts the valve 220, closing off the connection from the pipe 223 to pipe 230 so that discharge through the throttle valve 23! is out 01f, requiring the full discharge to take place through the valve 225, which thus slows the traversing motion of the carriage so long as the lead 23'! is supplied with energy by means which will later appear.

The length traverse determined by the dogs and 202 is that of the grinding traverse. The control member 204 may be dropped to an intermediate position where it is contacted by the dog 202, but is not contacted by the dog 20!. This permits an extended traverse until the dog 200 is contacted which is then effective to reverse the direction of traverse. takes place at the end of a rough grinding phase of the cycle and during this extended traverse the wheel may be trued as will later appear.

In the lowest position of the control member 204, the dog 202 is efiective to produce reversal Movable with the car--v This extended traverse of the direction of motion at the inner end of the stroke, but the dog 200 is ineffective to reverse the direction at the outer end of the stroke and the wheel carriage comes to rest against a. suitable stop. This action takes place at the end of the grinding cycle, whereupon a finished work piece may be removed from the work holder and a new piece substituted. The operation of the machine is then resumed by the operator, rocking the control member 204 by hand to again produce its inward stroke.

The control member 204 is moved from one to another of its axial positions by hydraulic mechanism. To this end the member 204 beneath the cannelure 222 is formed with a socket within which rides the upper end of a piston 245 provided with a vent opening 246 therethrough. This member 245 has an enlarged diameter portion 24'! which underlies the lower end of the member 204. When fiuid pressure is admitted through the pipe 248 beneath the portion 241, the piston 245 is pushed upwardly to its upper limit as determined by impingement on the lower end of the casing of the valve 22! of a stop nut 250. When pressure is admitted between the portion 24! and the lower end of the member 204, as through the pipe 252, the member 204 is moved to its top position with an enlarged diameter portion 253 at the upper end of the casing 22! When pressure is discharged from both of these places, the member 204 is in its lowest position at the end of the grinding cycle, and when fluid pressure is admitted beneath the piston portion 241, and is discharged from between this and the lower end of the member 204, the member 204 is in its intermediate position for extended wheel truing traverse.

The mechanism for controlling admission of fluid under pressure to produce the various positions of the control member 204 and to control the traverse, feed and retracting motions between the wheel and the work, to control the operative or inoperative positioning of the stop !15, the wheel dressing mechanism and the dressing compensator, include electrically actuated hydraulic valves A, B, C, D, E, F, G, H, J, and K, and the supply of electric power to determine the positions of these valves is controlled by a single control mechanism comprising a shaft 260 having thereon a plurality of cams 26la, 26!b, 26Ic, 26!d, 26 !e, together with a rotary cam 262 and an actuating ratchet wheel 263.

The position of the parts shown in Figure 10 is that of the finish grinding cycle during the relatively slow feed portion prior to the termination of the cycle and the withdrawal of the wheel slide. In this position of the parts the hole in the work has been ground to rough size at which the feeler head 62 may enter the hole in the work, as shown in this figure, when the wheel is sufliciently withdrawn therefrom. Electrical energy is derived from the lines 300 and 30!, the line 300 being the grounded side and the line 30! connected through leads 302 and 303 to a series of switches 304a, 304b, 3040, 304d, 304a and 3041, which are adapted to be closed at certain times by suitable cam projections on the cams 26|a to 26|e and 262. In the position shown, the switches 304d and 304s are closed. The closing of the switch 304d closes a. circuit through the leads 305, 306 and the solenoid 30'! to ground, lifting the valve D. This opens a communication from the pressure pipe 3!0 leading from the pump 2!! through the pipe and passage 3!! and 3!2, respectively, beneath the element I16, thus lifting this element against the pressure of the spring I11 and moving the stop I15 out of alinement with the piston I53, thus conditioning the parts for determining the limit of grinding not by the extent of feed, but by the air gage, as will later appear.

The closing of the switch 304s closes a circuit through the leads 3I5, 3I6 through the solenoid 3I1 to ground, this lifting the valve E. The lifting of the valve E opens the pipe I51 from the feed cylinder I55 past the valve E through the pipe and passage 3 I 8 past the valve G through the pipe and passage 328, past the valve H, which is now lifted through closing of the cycle contact switch 304d, through the passage 32I, the throttle valve 322, pipe and passage 323 and discharge pipe 324 which leads back to the discharge 226. The throttle valve 322 slows the feed to the desired point for finish grinding.

The valves G and H are both in lifted position, the valve G lifting solenoid 338 being energized from the lead 302 through the leads 326, 321, switch 328 which has been closed by finish feed cam I10, lead 329, solenoid 330 and to ground. The valve H is energized by the closingof the switch 304d, through the lead 305 and 306, the solenoid 335 to ground. This provides for slow feed, the discharge from the left hand of the feed cylinder I55 passing through pipe I51 past 'valve E, through pipe 3I8, past valves G and H,

through throttle valve 322, and pipe 323 to discharge pipe 324.

The valve K is also in lifted position, this being accomplished by the closing of the switch 3046 through the leads 305, 3I6, solenoid 331 to ground. This admits the pressure from the pressure line 3I0 past the lowered valve J and pipe 338 around the valve K and out through pipe 252 beneath the control member 204, and pressure is discharged through the pipe 248 from beneath the piston 241 through the pipe 248 around the valve J and through the pipe 340 to the discharge pipe 324. The control member 204 is thus in its lifted position for actuation by the dogs I and 202, which is thus in condition for the short grinding stroke of the carriage.

This condition takes place with the air gage stem entering the work on each retraction of the wheel therefrom until such time as the indicator bob 82 takes a position indicating the correct hole size at which it interrupts light from a light sources 350 from falling upon a photo-electric call 352. The light source 350 is energized from the secondary 353 of a transformer, the primary 354 of which is positioned across the lines 300 and I the current passing from the secondary 353 through lead I, switch arm 356, lead 351, lamp 350, lead 358, back to the transformer secondary held closed by the energization of the relay 359 from lead 3590, switch 2000, lead 306 and closed cycle switch 304d and lead 303. As long as light passes from the source 350 to the photo-cell 352, current flows from rectifier 3'6I fed from the transformer primary 354 through a resistor 360 in series with the cell 352. This current is derived from the leads 300 and 30I through a conventional half wave rectifier, indicated at 36I, from which leads 36.2 and 363 pass to the resistor 360 and to one terminal of the photo-cell 352, a lead 364 connecting the other side of the phototube to the resistor 3600. While current so passes, a negative bias is obtained from the resistor 360 and passes through the leads 365, 366 and 361 to the grid of the gas filled "thyratron tube 310, which blocks the anode dischar 31I from passing current through the relay 312, one side of which is connected thereto through the lead 313. The other side is connected through lead 314 through normally closed switch 315 and lead 316 to a variable resistor 321, one end of which is connected through the lead 318 with the rectifier 355 which derives energy across the lines 303 and 30I from the transformer 380.

As soon as the bob 8 2 interrupts the light passing to the photo-cell, the photo-cell passes less current and after a small time delay effective to prevent momentary cutting off this light from actuating the mechanism, the negative bias on the grid of the thyratron 310 is reduced to a magnitude which allows passage of plate current and energizes the relay 312. This time delay, as shown, is afforded by the resistor 360 with capacity 3650 inparallel therewith. Closing of the relay 312 closes a switch 38I, which through a lead 382 is connected to solenoid 383. Energization of this solenoid 383 steps around the cycle change mechanism by acting on the ratchet wheel 263. This closes the switch 304i by the cam 262 to the lead 384 through the ratchet solenoid 333,

. impressing a secondary turning impulse to the shaft 280 and insuring a one-eighth rotation of this shaft at each actuation. This turn of the ratchetwheel opens the cycle switches 304d and 304e and closes the switch 3046;, all the other cycle switches being open. The cycle mechanism is then in load angular position. Opening of the switch 304d deenergizes the relay 359 and extinguishes the lamp 350 since it allows the switch arm 356 to swing over, breaking contact with the lead 351 and making contact with the lead 385. The making of this contact with the lead 385 lights a second lamp 390 positioned beneath the lamp 350 and shielded therefrom by a partition 3 9I placed between them. The energization of the lamp 390 is from the transformer secondary 353 through lead 35I, switch 356, lead 385, lamp 390, lead 358 and back to the transformer secondary 353. The lamp 390' shines through a translucent window in the sides of the gage tube 1 1 beneath the Window through which the lamp lead 366 to thesolenoid392 and to ground. Energization .ofthe solenoid 392 lifts the valve A and allows fluid under pressure from the pressure pipe 31 0; to fiow through the pipe393 to the right hand end of the cylinder .I'2-l, driving its piston I22 to the left so retracting the air gage from the work. Opening of the switch 304e deenergizes the solenoid 331, allowing the valve K to fall, which opens the pipe 252 to discharge. The valve 304C being open, valveJ is also in the lowest position, opening pipe 240 to discharge. This allows the control member 204 to drop to its lowest position.

Opening of the switch 304e deenergizes the solenoid 3I1, allowing the valves E and F to drop, opening up'the left end of the feed cylinder I to The wheel carriage 2 thus fully retracts to loading position and the carriage I9 to fully retracted feed position, and since the memher 204 is notautomatically rockedtc reverse the. traverse, the wheel carriage stops in fully retracted position-against a suitable stop. The closing 1 l of the switch 304a also energizes the cycle start switch 4I0 through the lead 4| I so that when the switch M0 is closed in the next cycle of operations, the cycle control mechanism will be stepped along by a further one-eighth turn.

To start the cycle, the operator rocks the member 204, which at this moment is in its lowermost vertical position, allowing discharge at the fast rate from left end cylinder II, pipe I4, valve 201, pipe 220, cannelure 222, pipe 2230, pipe 226, to tank 2I2. The rocking of member 204 effects a reversal of the direction of traverse so that the wheel carriage starts at a fast speed 'rate toward the Work, and as soon as the switch 4I0 is closed by contact with the inclined face of the dog 4| 5 on the carriage, the ratchet solenoid 383 is energized through the lead 4I6 and the cycle control is stepped around to its second or rough grinding position in which switches 3041) and 3048 are closed, and switch 304a is opened. Closing of the switch 304e energizes the lead 3I6 and solenoid 3I1, lifting the valves E and F, opening fluid pressure to the right hand end of the feed cylinder and discharge from the left end, but under a fast rate. Energization of the lead 3I6 also energizes solenoid 331, lifting the valve K, which introduces fluid pressure beneath the valve 22I, lifting the control member 204 to its highest position for working traverse.

Before the wheel contacts the work in feed direction, the cam I12 has been rotated sufficiently to close the switch I120, which closes a circuit through the cycle switch 304b, leads 420 and 42I, switch I120, lead 329 and solenoid 330. This raises the valve G, which interposes the throttle valve 3220 in the discharge from the feed cylinder, the valve l-I being now lowered, cutting out the throttle valve 322.

The lower lamp 390 being now lighted and the gage being reciprocated in time with the wheel (the clinder I2| being discharged through pipe 393 past lowered valve B), the gage enters the hole in the work before the completion of the rough grinding which is terminated when the bob 82 shuts off light to the cell 352 from the lamp 390.

This, as before noted in connection with the finish grinding phase of the cycle, closes the switch 382 which steps the cycle control mechanism oneeighth of a turn to the dressing step of the cycle.

In this step, switches 304a and 3040 are closed.

Closing of the switch 304a completes the circuit through the switch 3000 and lead 396 to the solenoid 392, lifting the valve A, introducing fluid pressure through the pipe 393 to the right of the gage, retracting cylinder I2I which retracts the gage. It also energizes the relay 4I2 through the lead M3 and opens the switch 315 in the anode circuit of the thyratron 310. It also energizes the lead 4|I leading to the carriage operated switch 4I0, but on the retracting stroke of the carriage, the dog 4| 5 yields so that the switch 4| 0 is not operated. Closing of the switch 3040 energizes the lead 425, which through lead 426, energizes the solenoid 402 and lifts the valve J. This introduces fluid pressure through the pipe 248 beneath the piston 245, and as the solenoid 331 has been deenergized, the pipe 252 is open to discharge so that the control member 204 takes its intermediate position, extending the traverse. When the carriage closes the switch 236, the solenoid 240 is energized from lead 303, closed smitch 304e, lead 231, switch 236 and leads 238 and 239 and solenoid 240, lifting the valve 229, and slowing the traverse through the dressing throttle valve 225 only, and the valve B is lifted of this cylinder to discharge through the pipe H36,

and as soon as the retraction is complete the double switch arm 391 closes connection from lead 40I to lead 403. This establishes a circuit from lead 303, closed cycle switch 3040, leads 425, and

426, MI, 403 and solenoid 404. This lifts valve C which allows fluid under pressure to pass this valve through pipe |4I into the compensator cylinder I59, which produces the additional feed increment which compensates for wheel wear and truing. When cycle switch 3040 opens on the succeeding cycle control mechanism actuation, the valve C drops and passes discharge from the compensator cylinder, which returns the compensator feed to starting position. On the return traverse of the carriage, its stroke being reversed by turning of the member 204 by impingement by the dog 260, the switch M0 is closed by the dog 4I5, energizing the ratchet solenoid 383 and. stepping the cycle mechanism a further one-eighth turn to finish grinding condition shown in Figure 10.

When diamond rough sizing rather than air gage rough sizing control is desired, the switches 2000 and 3000 are placed in their dotted line position. These switches are effective only in the rough grinding portion of the cycle when switch 304D and 3046 are closed and the other cycle control switches are open. The closing of the switch 3000 to the switch 304b energizes the lead 396 and the solenoid 392, lifting the valve A, which causes fluid pressure to enter the right hand end of the cylinder I2 I' and retract the air gage. Closing the switch 3041) also energizes the relay 4| 2 and opens switch 315 and makes it possible for the thyratron tube to recover to the condition it had before the earlier impulse from a cell 352 caused the relay 312 to be energized. Closing the switch 2000 to the lead 302 energizes the relay 359 and causes the switch 356 to energize the finish grinding lamp 350. The valve D being lowered in this position of the cycle, the stop I15 is in line with the piston I53 so that rough grinding continues, first at a fast rate and then at a slower rate when the cam |1| closes the switch I120, until the piston I53 strikes the stop I15 and closes the switch I18. This closes a circuit from the lead 302 through a time delay, lead 435, switch I18, leads 436, 4360, and 392 to the ratchet solenoid 393 which then acts to step the cycle control mechaw nism to its truing position. The cycle may thus selectively control the rough grinding either by the air gage or by so-called diamond sizing, the latter depending upon the feeding limit during the rough grinding operation.

From the foregoing description of certain embodiments of this invention, it should be evident to those skilled in the art that various changes and modifications might be made without departing from its spirit or scope.

We claim:

1. In combination in a hole grinding machine, an air gage having a size indicator and a tubular stem provided at one end with a work feeler portion of enlarged diameter, said feeler portion having an air discharge opening through its periphery, a sleeve slidably surrounding said stem and having a counterbored end portion adapted at certain times to house said ieeler portion and of an internal diameter slightly different from the desired finished size of a hole in a work piece so that when said feeler is within said sleeve said indicator is out of desired finish size indi cating position, means supporting a Work piece with a hole coaxial with said stein, a grinding wheel, means for rotating said wheel, means for relatively reciprocating said wheel and work axially, means for relatively feeding said wheel and work transverse to said axis, means acting in time with such reciprocation to press said stem and sleeve toward the work to enter the hole being ground .therein when said hole hecomes oi' sufficient size to receive said stem at which time said discharge orifice leaves said sleeve and enters the work whereupon said indicator indicates the hole size, a cycle control mechanism, and means actuated and controlled by said indicator when said indicator indicates the desired hole size to actuate said mechanism to effect the succeeding step in the cycle of the machine.

2. An internal grinding machine comprising a rotary work spindle, means for supporting work with a hole to be ground coaxial with said spindle, a rotary grinding wheel, means for relatively moving said spindle and wheel lengthwise of said axis to cause said wheel to traverse the work and to have an extended traverse to separate said Wheel and work from each other, an air gage having a stem provided with a lateral orifice adapted to enter the hole in the work after such hole has been ground to nearly finished size, means acting in time with the relative traverse between the work and grinding wheel to present said stem to the work to enter therein when the hole is of sufficient size, a wheel truing device movable to and from a position to true the wheel during an extended traverse, means for producing a relative feed between the work and wheel laterally of the direction of traverse, a single control mechanism, means actuated at a predetermined feed position corresponding to termination of a rough grinding operation between said wheel and work to condition said control mechanism to effect extended traverse with wheel truing and then to resume grinding and feed, and means actuated by said air gage when said stem orifice enters the hole in the work and when said hole reaches desired finish size to efiect extended traverse to separate the wheel from the work and to then terminate the cycle.

3. An internal grinding machine, comprising a work holder, a grinding wheel, means for relatively moving said wheel and holder to cause said wheel to grind a hole in work carried by said holder, a hole size gage projectable into said hole when said hole is of suilicient size to admit it and including an upright column, means for alternately projecting and retracting said gage, a bob movable within said column and assuming a position therein corresponding to the hole size when said gage is in projected position, a cycle control mechanism determining a sequence of operations of a grinding cycle, and mechanism responsive to two positions of said bob in said column, in one position corresponding to roughing hole size and in the other position corresponding to finish hole size, to move said cycle control mechanism to the next controlling position in the cycle sequence.

4. An internal grinding machine, comprising a work holder, a grinding wheel, means for relatively moving said wheel and holder to cause said wheel to grind a hole in work carried by said holder, ahole size gage projectable into said hole when said hole is of sufficient size to admit it and including an upright column, means for alternately projecting and retracting said gage, a bob movable within said column and assuming a position therein corresponding to the hole size when said gage is in projected position, a cycle control mechanism determining a sequence of operations of a grinding cycle, means for projecting light beams across said column at either of two lengthwise positions one corresponding to a position of said bob corresponding to rough grinding size and the other to a position of said bob corresponding to finish size, and means responsive to the interruption of one and then the other of said light beams for moving said cycle control mechanism to the next following position.

WILLIAM J. BRYANT. THOR H. LJUNGGREN. WILLIS F. MOORE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,817,953 Stevens Aug. 11, 1931 1,862,215 Gallimore June 7, 1932 1,927,750 Mennesson Sept. 19, 1933 2,001,447 Balsiger May 14, 1935 2,010,706 Williams Aug. 6, 1935 2,050,261 Blood Aug. 11, 1936 2,465,035 Polk et a1. Mar. 22, 1949 2,471,737 Fox May 31, 1949

Images