US3060647A

US3060647A - Phase-out device for grinding machine

Info

Publication number: US3060647A
Application number: US99797A
Authority: US
Inventors: Albert H Dall; George L Grove
Original assignee: Cincinnati Milling Machine Co
Current assignee: Milacron Inc
Priority date: 1961-03-31
Filing date: 1961-03-31
Publication date: 1962-10-30
Anticipated expiration: 1979-10-30
Also published as: GB947447A; DE1254989C2; DE1254989B

Description

Oct. 30, 1962 A. H. DALL ETAL PHASE-OUT DEVICE FOR GRINDING MACHINE 8 Sheets-Sheet 1 Filed March 31, 1961 lea 195 |86 AT TO RNEYS Oct. 30, 1962 A. H. DALL ETAL PHASE-OUT DEVICE FOR GRINDING MACHINE Filed March 31, 1961 8 Sheets-Sheet 2 ILS 6 SOL H4 3 IOI Oct. 30, 1962 A. H. DALL ETAL 3,060,647

PHASEOUT DEVICE FOR GRINDING MACHINE Filed March 31, 1961 8 Sheets-Sheet 3 Oct. 30, 1962 A. H. DALL ETAL 3,060,647

PHASE-OUT DEVICE FOR GRINDING MACHINE Filed March 31, 1961 8 Sheets-Sheet 4 Oct. 30, 1962 A. H. DALL ETAL 3,

PHASE-OUT DEVICE FOR GRINDING MACHINE Filed March :51, 1961 8 Sheets-Sheet 5 44 230 I /Il 233 44 2I9 ZSOL Wk 1119?.

' 226 an m 2l5 227 $9 Oct. 30, 1962 A. H. DALL ETAL 3,060,647

PHASE-OUT DEVICE FOR GRINDING MACHINE Filed March 51, 1961 s Sheets-Sheet s Oct. 30, 1962 A. H. DALL ETAL PHASE-OUT DEVICE FOR GRINDING MACHINE Filed March 31, 1961 8 Sheets-Sheet 8 4, 3L5 86R CONTACTS FOR 3L5. l7.

II s TRUING IN Q MOVES TRUING SLIDE IN 55 V IN MANUAL. 7,7. AUTO. MANUAL STOP MOVES TRUING SLIDE OUT IN MANUAL.5,5,9. RAP m R Q MOVES TRUING sI IDE AT RAPID RATE IN RE- ePB U VERSAL.9. ..3TR ll zTR ZTR CR DIAMOND ADvANcE 7n RELAY. l0,l0,37.

'\l HELD BY COMPENSATING RATCHET WHEEL AT PHASE-OUT POSITION.

COARSE COMPENSATION RELAY.4,4.

FINE COMPENSATION RELAY. 3,3

SETS UP CIRCUIT FOR PHASE-OUT COMPENSA- TION. 40 ,4I.

ADVANCE TRUING DIA- MOND WHEN ACCUMU- LATED COMPENSATIONS EQUAL A TRUING DIA- MOND ADVANCE. 33,39.

PREVENTS COARSE COM- PENsATIoN DURING PI-IAsE-ouT. 3 7.

United States Patent 3,060,647 PHASE-OUT DEVICE FOR GRINDING MACHINE Albert H. Dali and George L. Grove, Cincinnati, Ohio,

assignors to The Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of Ohio Filed Mar. 31, 1961, Ser. No. 99,797 9 Claims. (Cl. 51-165) This invention relates to a wheel truing mechanism for use with precision grinding machines, and, more particularly, to an apparatus for keeping the wheel truing tool in phase with the wear compensating mechanism of the grinding machine so that after a truing operation, the location of the grinding wheel relative to the work supporting means will be such as to cause the machine to grind parts of the correct diameter.

An important feature of present day precision grinding machine resides in the automatic truing apparatus which maintains a sharp, accurate cutting face on the grinding wheels of such machines. In keeping with the trend toward more and more automated equipment, it is now common practice to provide automatic controls for such machines which will cause the automatic grinding process to be stopped after a predetermined number of parts have been ground and thereupon initiate truing of the grinding wheel. After the wheel has been trued, the automatic grinding process once again will be resumed and the parts will continue to be ground until the next wheel truing operation is initiated. The point where the grinding cycle stops and the truing cycle begins is ordinarily signaled by a counter which is preset in accordance with p the number of parts to be ground between truing cycles. When the predetermined number of parts have been ground, a signal from the counter stops the grinding process and starts the automatic truing cycle. On each pass of the truing tool across the grinding wheel, a predeter-.

mined amount of material is removed therefrom and the diameter of the wheel is thereby reduced. Accordingly, a compensating mechanism is ordinarily provided to cause the grinding wheel to be moved toward the work through a distance equal to the amount of material removed from the wheel so that when the grinding operation is resumed, the parts will be ground to the correct diameter. At the conclusion of the truing cycle, a signal is given to restart the grinding process. This otherwise straight forward procedure is complicated, however, by the fact that it is usually necessary to compensate for wheel wear between truing cycles in order to prevent over-size parts. In other words, the wheel slide is moved independently of the truing tool during the grinding process so that the tool and slide tend to get out of phase and cause the machine to produce undersized parts when grinding is resumed. The purpose of the present invention is to provide a simple and practical device for bringing the truing tool and wheel slide back into phase during the automatic truing cycle whereby parts of the correct diameter will be ground by the machine after the wheel has been trued.

Accordingly, it is an object of the present invention to provide a new and improved phase-out device for precision grinding machine.

Another object of the invention is to provide a simple mechanical device for bringing the truing tool of a grinding machine back into phase with the wheel slide during the course of an automatic truing cycle.

Another object of the invention is to provide a new coarse-fine compensating mechanism for grinding machines in which the amount of coarse compensation given the wheel slide is in complementary relationship to the number of fine compensations introduced therein.

With these and other objects in view, which will become apparent from the following description, the invention includes certain novel features of construction and combinations of parts, the essential elements of which are set forth in the appended claims, and a preferred form or embodiment of which will hereinafter be described with reference to the drawings which accompany and form a part of this specification.

In the drawings:

FIG. 1 is a front view of a grinding machine incorporating the teachings of the present invention.

FIG. 2 is a cross-sectional view taken along the line 2-2 in FIG. 6.

FIG. 3 is a transverse section through the truing tool for the grinding wheel.

FIG. 4 is a detailed view, partially in cross section, showing the feed mechanism for the truing tool.

FIG. 5 is a diagrammatic view of the hydraulic circuit of the wheel truing apparatus.

FIG. 6 is a front elevation of a portion of the machine shown in FIG. 1 with parts broken away to show the internal construction.

FIG. 7 is a diagrammatic view of the hydraulic circuit for the wheel slide feed mechanism.

FIG. 8 is a cross-sectional view taken along the line S8 in FIG. 6.

FIG. 9 is a cross-sectional view taken along the line 99 in FIG. 6.

FIGS. 10a and 10b constitute a wiring diagram of the electrical control circuits for the machine shown herein.

FIG. 11 is a schematic view illustrating the principle of operation of the phase-out mechanism.

In the detailed specification to follow, similar reference characters designate similar or identical elements and portions throughout the specification and throughout the different views of the drawings.

In FIG. 1 is shown a centerless grinding machine of a known type to which the new phase-out device has been applied. It will be appreciated, however, as the description proceeds, that the present invention might equally well be applied to other known forms of grinders of either centerless or center type construction. As shown in FIG. 1, the grinder is provided with a base 12 upon which is journaled a grinding wheel 13 enclosed within a wheel guard 14. The grinding wheel is arranged to be driven by a motor (not shown) also supported on the base 12. A regulating wheel 15 is supported for rotation about its axis on a wheel slide 16 which is mounted for sliding movement on a lower slide 17. This slide has secured thereto a work-rest blade 18 which serves as a support for a workpiece 19 disposed between the grinding wheel 13 and the regulating wheel 15. A drive motor (not shown) is provided for driving the regulating wheel 15 in a known manner.

For set up purposes the wheel slide is provided with a handwheel 21 which is adapted to rotate a nut rotatably journaled in the slide and meshing with a feed screw. This mechanism is fully explained and described in U.S. Patent No. 2,709,877 to which reference may be had for a complete disclosure of this portion of the mechanism.

After a predetermined number of workpieces have been ground by the machine, it is necessary to true the grinding wheel and, for this purpose, a truing mechanism 22 has been provided. This mechanism, which is supported on a bracket 23 mounted on the base of the machine, is fully automatic in operation and may be of the type disclosed in U.S. Patent No. 2,937,639 to which reference is made for a detailed disclosure thereof. In the present drawings only so much of the automatic truing mechanism is shown as is necessary for a complete understanding of the present invention. In using this mechanism, the operator determines the number of truing passes to be made by the truing tool across the face of the grinding wheel and sets this number on a dial 24 of a counter 25 contained in an electrical cabinet 26. The automatic truing cycle may then be initiated by depressing a Truing Start push button SP3 to cause the diamond tipped truing tool to traverse back and forth across the grinding wheel 13 with automatic advance of the diamond on each pass until the selected number of passes have been made. In the present disclosure, the counter usually provided for counting the number of workpieces ground between truing operations has not been shown though it will be appreciated that a signal from such a counter might be utilized in accordance with the prior art teachings instead of the push button SPB.

Referring now to FIG. 3 of the drawings, the diamond is suitably mounted on the forward end of a truing bar 30 which is supported for longitudinal sliding movement Within a tubular housing 31 by means of suitable bearing surfaces provided at the ends of the housing. The housing, in turn, is mounted for longitudinal shifting movement within a traversing carriage 32 by means of balls 33 running in tracks provided on the housing 31 and on the carriage 32.

Traversing movement of the carriage 32 on the bracket 23 is eifected by means of a lead screw 34 (FIG. which is driven by a hydraulic motor 35 and meshes with a nut in the carriage.

The advance of the truing tool toward the grinding wheel prior to each truing pass is effected by means of a feed screw 36 which, when rotated, causes feeding movement of the truing bar 30 (FIG. 3) relative to the housing 31. For the purposes of the present invention, the housing 31 may be considered as fixed with respect to the carriage 32. The means for advancing the truing bar by means of the feed screw 36 will hereinafter be described.

The hydraulic circuit for effecting traversing movement of the carriage 32 is shown in FIG. 5 of the drawings. As illustrated therein, hydraulic fluid is delivered to a pressure line 40 by a pump 41 driven by an electric motor (not shown). The pump draws fluid out of a reservoir 42 and delivers it to the pressure line 40 at a constant pressure determined by the setting of a relief valve 43 which discharges excess fluid back into the reservoir 42. An exhaust line 44 returns fluid to the reservoir from the various hydraulic components contained in the circuit.

As mentioned above, the feed screw 34 which traverses the carriage 32 back and forth with respect to the grinding wheel 13, is driven by a hydraulic motor 35. This motor is connected by

hydraulic lines

45 and 46 to a reversing valve 47. This valve is operated by a solenoid valve 48 which valves fluid under pressure to the ends of the reversing valve through

lines

49 and 50 thereby shifting the spool of the latter valve in one direction or the other.

The pilot valve 48 contains a spool 52 which is held in a centered position within the valve body by means of compression springs 53 and centralizing washers 54. The valve is provided with a centrally disposed pressure port which is connected to the pressure line 40, and with a pair of exhaust ports located on opposite sides of the pressure port which are connected with the exhaust line 44 through a check valve 55. Hence, when the solenoid 3SOL is energized, the spool 52 will be shifted to the left, as viewed in FIG. 5, thereby connecting the line 49 with the pressure line 40, and the line 50 with the exhaust line 44. This will cause pressure to be applied to the left hand end of the reversing valve 47 and will connect the right hand end of this valve to exhaust. As a result, a spool 56 which is normally held in a centered position by compression springs 57 and centralizing washers 58, will be shifted to the right thereby connecting a pressure port '59 with the motor line 46, and connecting the motor line 45 with a port 60 which is connected to a return line 61. The motor 35 will thereby be rotated in a direction to drive the carriage away from home position, i.e., the position in which a dog 64 (FIG. 3) secured to an elongated bar 65 mounted on the carriage 32 is in contact with the arm '66 of a limit switch 31.3. This limit switch and a companion limit switch 2LS are mounted in a housing 67 attached to the wheel guard 14.

Referring again to FIG. 5, if solenoid 4SOL is energized in place of solenoid 3SOL, the spool 52 will be shifted to the right and cause spool 56 to be shifted to the left thereby connecting a pressure port 68 to the motor line 45 and connecting the return port 60 to the motor line 46. This will cause the motor 35 to rotate in the opposite direction and move the carriage from a reversal position, as represented by engagement of a dog 69 (FIG. 3) with the arm 70 of limit switch ZLS, toward home position. The return line 61 is connected by a line 73 with a pressure reducing valve 74. This valve contains a sliding plunger 75 having a transverse bore 76 and a longitudinal bore 77 communicatively connected therewith. The bore 77 extends to the bottom of the plunger 75 and transmits fluid to a chamber 78 provided in the bottom of the valve. The pressure of the fluid in the chamber 78 will tend to raise the plunger against the urgency of a compression spring 79, this upward movement of the plunger tending to cut off the port to which the line 73 is connected. Accordingly, the plunger will be stabilized when the pressure in the chamber 78 equals the pressure acting on the top of the plunger. Since the downward force acting on the plunger is constant, the pressure in chamber 78 will also remain constant and a constant pressure will thereby be maintained at the outlet port 88. This port is connected by a line 81 with a rate valve 82 which may be adjusted by rotating a knob 83 to vary the amount of oil permitted to flow through an outlet port 84 on the valve. This port is connected by a line 85 with a relief valve 86 which is connected to the exhaust line 44. The pressure in the line 85 will thereby be maintained constant in accordance with the setting of the relief valve 86. Hence, fluid admitted to the top of the pressure reducing valve 74 through a line 87 will also be maintained constant. The pressure thus provided on top of the plunger 75 will be added to that of the spring 79 and will improve the linearity of the valve 74. Hence, by manipulation of knob 83 of rate valve 82, the feed rate of the truing tool across the grinding wheel may be adjusted as desired.

The hydraulic circuit includes a rapid traverse valve 90 which is effective, when operated, to bypass the rate valve and connect the return line 61 directly to the exhaust line 44-. This valve is provided with a spool 91 which is normally held in its left hand position as shown in FIG. 5 by a compression spring 92. In this position of the spool, a line 93 connected to the return line 61 is blocked by a land on the spool. However, when a solenoid SSOL is energized, the spool 91 will be moved to the right against the urgency of spring 92 and the line 93 will be communicatively connected with the exhaust line 44 thereby bypassing the rate valve and permitting the motor 35 to run at full speed.

Automatic advance of the truing bar 30 is effected by means of a pawl and ratchet mechanism illustrated in FIG. 4 of the drawings. As therein shown, a piston 95 is slidably received within a cylinder 96 provided in the base portion 97 of a housing 98 secured to the outer end of the truing bar 30. As shown in FIG. 4, the right hand end of the cylinder 96 is closed by a cap 99 while the left hand end of the cylinder is closed by a bushing 100 which is adjustably secured to the housing 98 by cap screws 101 and set screws 102. The bushing 100 is provided with an axial bore for receiving the stem 103 of a diamond advance selector knob 104 which may be turned to any one of four positions to select different amounts of diamond advance. As shown in FIG. 4, the right hand end of the stem 103 serves as a stop to limit left hand movement of the piston 95 while the cap 99 serves as a stop to limit right hand movement of the piston within the cylinder. The piston is bored to receive a compression spring 105 which presses on the end of the stem 103 and thereby urges a pin 106 projecting radially from the stem into engagement with the inner edge of the bushing 1110. The edge of the bushing is provided with four notches 107 of varying depth for receiving the pin 106. Hence, by pressing in on the knob 104 and turning the same, any one of the notches 107 may be selected to receive the pin 1116, thereby providing four different degrees of adjustment of the inner end of the stem 86 relative to the left hand end of piston 95.

Thus, four different strokes of movement are permitted the piston, which strokes are effected under hydraulic pressure controlled by a valve located in the bottom portion 97 of the housing 98. This valve includes a spool 110 which is slidably received in a cylindrical bore provided in the base portion 97 and which is urged toward the right by a compression spring 111. The spool is thereby maintained with its right hand end bearing against the inner edge of a bushing 112 located in the end of the cylindrical bore. An intermediate portion of the bore is connected by a channel 113 with the right hand end of the cylinder 96. When the spool 1 19 is in the position shown in FIG. 4, this channel is communicatively connected with the exhaust line 44 (FIG. 5), thereby permitting the spring 105 to move the piston 95 to the limit of its movement in the right hand direction. However, when solenoid 6SOL is energized, a plunger 114 passing hrough a bore in the bushing 1 12 will be projected outwardly against the right hand end of the spool 110 and shift the latter to the left against the force of the spring 111. With the spool in this position, the channel 113 will be communicatively connected with the pressure line 40 (FIG. 5) whereby hydraulic fluid under pressure will be admitted to the right hand end of the cylinder 96 thereby driving the piston 95 to the left. When the solenoid is deenergized, the spring 111 will return the spool to the position shown in FIG. 4 thereby again connecting the right hand end of the cylinder 96 with the exhaust line 44 whereupon the spring 105 will return the piston to the position shown. As heretofore mentioned, the stroke of the piston is determined by the setting of the selector knob 104 so that different degrees of diamond advance may be obtained.

The upper edge of the piston 95 is provided with rack teeth which mesh with the teeth of a spur gear 115, the upper portion of which is removed to provide a seat for a block 116 which is screwed fast to the gear. Situated adjacent the gear 115, which is freely rotatable on the feed screw 36, is a ratchet wheel 117 which is pinned to the screw 36. The wheel 117 is arranged to be driven by a pawl 118 which is pivoted on a stud 119 carried by the block 116. The pawl is urged in a clockwise direction about the stud 119 by a compression spring 120' interposed between the block and the pawl thereby engaging the pawl with the teeth of the ratchet wheel 117. Hence, when the piston 95 is driven to the left as viewed in FIG. 4 thereby turning the gear 115 clockwise, the pawl 118 will turn the ratchet wheel 1'17 and the lead screw 36 in a similar direction. When the piston 95 returns to the right, thereby driving the gear 115 in a counterclockwise direction, the pawl 118 will ratchet over the teeth of the wheel 117 and the feed screw 36 will remain stationary. Depending on the setting of the selector knob 104, the ratchet wheel will be advanced through a distance of l, 2, 3, or 4 teeth thereof and cause corresponding amounts of diamond advance.

To permit manual operation of the feed screw 36 in either direction by a handwheel (not shown), an Auto- Manual selector knob 123 is provided on the side of the housing 98. This knob is adapted to rotate a hub 124 carrying an eccentrically mounted lug 125 which lies beneath the right hand end of the pawl 118. Hence, when the knob 123 is turned 180 degrees, the lug 124- Will elevate the pawl and disengage it from the teeth of the ratchet wheel 117. At the same time, the upper edge of the pawl will engage the plunger of a limit switch \1LS mounted on a bracket in the top of the housing 98 and, through means shown in the wiring diagram in FIGS. 10a and 10b, will disable the automatic truing control circuit.

In setting up the machine for a particular grinding operation, the wheel slide 16 is clamped to the lower slide 17 by tightening a clamp 21 (FIG. 1) on the side of the wheel slide. At the same time, a clamp 27 is loosened to permit the lower slide to move with respect to the base 12. The hand wheel 21 is then turned to feed the wheel slide 16 and lower slide 17 as a unit along the feed screw until the workrest blade 18 is brought into the proper position. The clamp 27 is then tightened and the clamp 29 is loosened to permit the desired setting of the regulating wheel independently of the workrest blade 18. A clamp 128 (FIG. 1) is then tightened to clamp the nut with respect to the wheel slide 16 as explained in US. Patent No. 2,709,877 to thereby enable feeding movement of the wheel slide to be effected by rotation of the feed screw.

As shown in FIG. 6, the machine is preferably provided with a walking beam type of infeed mechanism as disclosed in US. Patent No. 2,718,101. As shown herein, the walking beam 129 is connected by pivot pins .130 and 131 to a sleeve 134, the corresponding parts in US. Patent No. 2,718,101 being numbered 29, 30, 31 and 34. In that patent however the sleeve is pinned to the feed screw herein numbered 135, whereas in the present machine the sleeve is journaled for rotation on the feed screw by means of a thrust bearing 136 and a combined radial and thrust bearing 137. These bearings are interposed between the feed screw 135 and the sleeve 134 and are held in place between a nut 138 threaded on the feed screw and a shoulder 137 likewise provided on the feed screw.

As explained in US. Patent No. 2,718,101 the walking beam operates to bodily move the feed screw in an axial direction to effect rapid traverse movement of the wheel slide for infeed movement of the regulating wheel with respect to the workpieces being ground.

Since in the present embodiment, the feed screw 135 is journaled for rotation with respect to the walking beam 129, it is desirable for setup purposes to provide a clamp screw 139 threaded into a tapped hole in pivot pin for preventing rotation of the lead screw when the clamp screw is tightened. This is for the purpose of preventing rotation of the feed screw when the handwheel 21 is manipulated to rotate the nut during the setup of the machine. In the following description of the compensating feed mechanism for the wheel slide 16 it will be assumed that the machine has been properly setup and that the clamp screw 139 has been loosened so as to permit rotation of the feed screw. It will also be assumed that the clamp 128 (FIG. 1) has been tightened to prevent rotation of the nut in the wheel slide whereby rotation of the feed screw will effect feeding movement of the slide.

Secured to the right hand end of the base 12 is a subframe 142 (FIG. 6) which supports the compensating feed mechanism hereinafter to be described. The right hand end of the feed screw extends into the subframe where it is fitted with a spur gear 143. This gear is securely fastened to the end of the feed screw and is provided with a hub 144 having finished end face 145. This face is adapted to abut against a finished surface 141 provided on the right hand end of the base 12. The gear 143 meshes with a pinion 146 formed on a shaft 147 which is journaled for rotation in the subframe by antifriction bearings 148 and 149. Secured to the shaft 147 by a pin 150 is a fine ratchet wheel 151 provided with a large number of ratchet teeth 152 (see also FIG. 9). Co operating with the ratchet teeth 152 are pawls 153 154 (FIG. 6) which are pivoted on a screw 155 9) carried by an arm 156. The arm 156 is journalibh the shaft 147 by antifriction bearings 157 and is provided with a lateral extension 158 which supports a pair of compression springs 159 acting on the free ends of pawls 153 and 154. The pawls are thereby resiliently urged toward the periphery of the ratchet wheel 151 so as to maintain an advancing tooth 160 on each of the pawls in engagement with the ratchet teeth 152. A pair of retaining pawls 161 pivoted on a bracket 162 extending from the frame 142 are urged by compression springs 163 into engagement with the teeth of ratchet wheel 151 to resiliently hold the ratchet wheel in the position to which it is moved by the pawls 153 and 154 and to prevent retrograde movement of the wheel.

Secured to the right hand end of shaft 147 (FIG. 6) by a key and a retaining nut 167 is a coarse ratchet wheel 168. As shown in FIG. 8 this wheel is provided with ratchet teeth 169 which are considerably fewer in numher than the teeth on the fine ratchet wheel previously described. The teeth 169 are adapted to be engaged by an inserted tooth 170 provided in a pawl 1'71 pivoted on a screw 172 carried by an arm 173. As shown in FIG. 6, the arm 173 is journaled for rotation on the shaft 147 by antifriction bearings 174 and is provided with a lateral extension 175 supporting a compression spring 176 which presses against the free end of pawl 171 and resiliently urges the tooth 170 into engagement with the teeth 169.

Also cooperating with the teeth 169 of the coarse ratchet wheel 168 is a sensing pawl 179 pivoted on a screw 13%. The pawl is provided with an inserted tooth 181 which is urged into contact with the teeth 169 by a compression spring 182. On the opposite side of its pivot, the pawl is provided with an adjustment screw 183 which is adapted to cooperate with the operating plunger of a limit switch 4L5 carried by a bracket 184 secured to the frame 142. The ratio of the lever arms of the pawl 179 is such that a small movement imparted to the pawl by the inclined surface of a tooth 169 is amplified into a much larger movement of the screw 183. The screw 18?: is adjusted until it just operates the limit switch 4LS with the tooth 181 located in the bottom of a tooth space as shown in FIG. 8. The setting should be such that even a slight movement of the tooth 181 up the inclined face of a tooth 169 will release the limit switch.

The

pawl arms

156 and 173 are provided with downwardly projecting teeth 136 (FIG. 2) and 187 (FIG. 9), respectively, which engage in notches 188' and 189 formed in a fine plunger 190 and a coarse plunger 191. The plunger 190 (FIG. 2) operates in a cylinder 192 formed in the frame 142. Likewise, the plunger 191 operates in a cylinder 193 also formed in the frame 142. The plunger 190 is urged toward the right against a sealing plug 194 by a compression spring 195 which is compressed between the plunger and adjustable sealing plug 196. In a similar manner, the plunger 191 (FIG. 9) is urged toward the right against the end of a sealing plug 197 by a compression spring 198 which is compressed between the plunger and an adjustable sealing plug 199. As shown in FIG. 2, left hand movement of the plug 196 is prevented by a stern 202 of a setting knob 204. The stem 202 is slidable within a bushing 203 secured to the frame 142 and carries a radially extending pin 205 which is adapted to engage in any one of four notches provided on the end of a sleeve 206 fitted in the bushing 203. These notches are of different depth so as to permit varying degrees of movement of the plunger 190 to the left against the urgency of its spring 195.

Similarly, left hand movement of the adjustable plug 199 is limited by the stem 207 of a setting knob 209. The stem 207 is slidably received in a bushing 208 secured to the frame 142 and carries a radially extending pin 210 which is adapted to cooperate with any one of four circumferentially spaced notches in the end of a sleeve 211 fitted in the bushing 208. These notches are of varying depth to permit different degrees of movement of the plunger-191 to the left.

The hydraulic control circuits for the plungers and 191 are shown in FIG. 7 of the drawings. In this circuit the pressure and

exhaust lines

40 and 44 are understood to be connected to the corresponding lines shown in FIG. 5. Operation of the plunger 190 for the fine ratchet wheel 151 is controlled by a solenoid valve 214 while operation of the plunger 191 for the coarse ratchet wheel 168 is controlled by a solenoid valve 215. The valves are fitted with

spools

216 and 217, respectively, which are urged toward the left by

compression springs

218 and 219. When the spool 216 is in the position shown in FIG. 7, fluid under pressure is delivered from line 40 to a line 220 while the exhaust line 44 is connected to a line 221. Hence, fluid under pressure is delivered to the space between the left hand end of plunger 190 and the a ustable plug 196 so as to maintain the plunger in its right hand position. When the solenoid ISOL is energized, the spool 216 will be moved to the right against the urgency of spring 218 thereby causing fluid under pressure to be applied to the line 221 and line 220 to be connected to exhaust. Hence, the plunger 190 will be moved to the left to the extent permitted by the setting of the stem 202 and the ratchet wheel 151 will be advanced by the pawls 153, 154. When solenoid ISOL is dienergized, the spool 216 will be returned to the position shown in FIG. 7 by spring 218 and the plunger 190 will be returned to its initial position thereby returning the feed pawls to their starting positions.

In a similar manner, when the coarse solenoid 2SOL is energized, the spool 217 will be moved toward the right against the urgency of the spring 219 and cause fluid under pressure to be applied to a cylinder line 224 while a line 225 will be connected to the exhaust line 44. Hence, the plunger 191 will be moved toward the left against the urgency of the compression spring 193 to the extent permitted by the setting of the stern 207. The pawl arm 173 will thereby be rotated clockwise and cause the coarse ratchet wheel 168 to be given a step of advancing movement by the pawl 171. When the solenoid 2SOL is deenergized, the spool 217 will be returned to the position shown in FIG. 7 as will also the plunger 191 and the feed pawl 171. In order to prevent overthrow of the coarse ratchet wheel 168 on the advancing stroke, a check valve 226 and resistance 227 are inserted in parallel in the line 225 as shown. Hence, when pressure is applied to the right hand end of the plunger 191, fluid exhausting from the left hand side of the plunger through line 225 will be prevented from passing through the check valve 226 and forced to flow through the resistance 227 on its way to the exhaust line 44. This will slow the movement of the plunger and prevent overthrow. When the solenoid ZSOL is deenergized, pressure from line 40 will be applied to the line 225 and will be permitted to flow unimpeded through the check valve 226 on the return stroke of the pawl 171.

To facilitate setting of the

stems

202 and 207, a pressure release button 230 is provided. This button is connected to the spool 231 of a valve 232 to which the pressure and

exhaust lines

40 and 44 are connected as shown. The spool 231 is normally urged toward the left by a compression spring 233 so that the spool prevents fluid under pressure in the line 40 from flowing out through the exhaust line 44. However, when the button 230 is held depressed against the urgency of spring 233, the line 40 will be communicatively connected with the line 44 thereby dropping the pressure in the system to a point where the

knobs

204 and 209 may easily be pressed inwardly against the urgency of springs and 198 and rotated to the position desired.

The mode of operation of the mechanism thus far described is as follows: Fine compensation for wheel wear occurring during the grinding process is effected by advancement of the fine ratchet wheel 151 under the control of the solenoid operated valve 214. As the grind ing wheel wears and the parts being ground tend to become oversize, the solenoid 1801. is energized by the operator to give the pawl arm 156 a feeding movement thereby advancing the ratchet wheel 151 and the feed screw 135 of the grinding machine infeed mechanism. When the knob 204 (FIG. 7) is adjusted for the smallest possible increment of wheel wear compensation, the stroke permitted the plunger 1% is such as to move the pawl tooth 160 through a distance equal to one-half of a tooth space. For this purpose the pawls 153 and 154 (FIG. 6) are offset from one another by a distance equal to one half of a tooth space so that on successive strokes of advancing movement of the pawl arm 156, alternate pawls will be operative to advance the ratchet wheel through a distance equal to one half of a tooth space. The retaining pawls 161 are also offset from one another by a distance equal to one-half of a tooth space so that one of these pawls will always drop behind a ratchet tooth upon a half-step advance of the ratchet wheel.

In the case of the coarse ratchet wheel 168 which is secured to the shaft 147 and moves as a unit with the fine ratchet wheel 151, this wheel may, for example, be provided with only one fifth as many ratchet teeth as the wheel 151. Hence, ten oscillations of the fine ratchet arm 156 will be required to advance the coarse ratchet wheel 168 through a distance of one tooth space. The Wheel slide compensation effected by a movement of the coarse ratchet wheel through a distance of one tooth space is desirably made equal to the advance of the truing diamond each time the plunger 95 (FIG. 4) is reciprocated under the control of solenoid 6SOL. It will thus be appreciated that for each advance of the fine ratchet wheel through a distance of one half tooth space, the coarse ratchet wheel will be advanced through a distance equal to one tenth of a tooth space. Hence, if after a wheel truing cycle has been effected, a total of, for example, four fine compensations are entered under the control of solenoid ISOL, then the tooth 170 of the coarse feed pawl 171 will have moved four tenths of the way up the inclined face of a tooth 169 as illustrated in FIG. 11. If, now, a truing operation is initiated, the diamond will, due to the amount of wheel wear occurring during the grinding operation, remove only six tenths of the normal amount of material from the surface of the grinding wheel since no provision is made for incrementally advancing the diamond to compensate for wheel wear. Hence, in order to maintain the wheel slide in phase with the diamond, it is desirable that the wheel slide be advanced only to an extent corresponding to the amount of material which will be removed by the diamond on its first pass across the wheel. Hence, if a coarse compensation of the wheel slide is now entered by energization of solenoid 2SOL, the coarse pawl arm 173 will be oscillated but the coarse ratchet wheel 168 will be advanced through a distance of only six-tenths of a tooth space. This results from the fact that four-tenths of the movement of the pawl tooth 170 will be lost motion. In other words, the pawl will move idly until it engages the tooth and advances it through the final six-tenths of the stroke of the pawl.

Since the wheel truing mechanism of the present machine is provided with four degrees of diamond advance, as controlled by the knob 104 (FIG. 4), it is desirable to enable the advance of the coarse ratchet wheel 168 to correspond therewith. As previously described, the advance of the plunger 191 may be adjusted to four different degrees of movement by appropriate setting of the knob 209. Each adjustment of the knob 209 is therefore made to correspond with one of the adjustments of the diamond advance knob 104 and a set of four coarse ratchet wheels 168 is provided with each machine. Each of the wheels is provided with a tooth spacing corresponding to one of the four strokes of movement given to the pawl 171 by its arm 173. To permit interchange of the coarse ratchet wheels, the frame 142 is provided with a cover 235 (FIG. 6) which may be removed to provide access to the end of the shaft 147. By then removing the nut 167, the ratchet wheel 168 may be removed and another wheel inserted in its place. With the substitution of a new coarse ratchet wheel 168 on the shaft 147, the stroke adjustment knob 204 for the fine plunger (FIG. 2) may be set to provide for the appropriate size stroke of the arm 156 to effect an advance of the coarse ratchet wheel through one tooth space for each ten oscillations of the fine pawl arm. For example, the strokes of this arm may include, in addition to the stroke equal to one-half of a tooth space as previously mentioned, strokes equivalent to one, one and a half and two tooth spaces.

Referring now to the electrical control circuits for the automatic truing and phase out mechanisms as shown in the wiring diagram (FIGS. 10a and 10b), energy for the circuits is provided from a source 236 which is connected to a pair of

conductors

237 and 238 across which the various energizing circuits are connected. A series of reference numbers is provided along the left hand margin of the wiring diagram to indicate the lines of the diagram on which the various contacts and components appear. In the right hand margin of the diagram are provided legends for indicating the functions performed by the solenoids, relays, etc. The. numbers following the legends refer to the lines of the diagram in which the relay contacts are found, the underscored numbers designating normally closed contacts.

To condition the grinding machine for operation a Master Start pushbutton 2P3 (line 11) is depressed thereby energizing the relay 2M which starts the hydraulic pump motor to provide operating pressure for the hydraulic circuits. When the relay 2M is energized, its contacts in line 12 are closed around the pushbutton switch 2PB thereby maintaining the relay energized after the pushbutton is released. The relay may be deenergized to stop the motor by depressing the Master Stop pushbutton lPB which breaks the circuit through the relay and stops the motor. Although not shown in the present wiring diagram, corresponding starting circuits may be provided for the other prime movers of the grinding machine.

To start an automatic truing cycle, the Truing Start pushbutton SPB in line 15 is depressed thereby energizing a clutch coil 240 of the counter 25 (FIG. 1). The clutch coil is maintained energized by the cont-acts 7CR (line 16) of a relay 7CR (line 28) which is energized by closure of contacts COB-1. The contacts COB1 are provided in the counter 25 and remain closed so long as the clutch coil 240 is energized.

As heretofore indicated, the counter 25 controls the number of passes of the truing tool across the face of the grinding wheel. The counter per se forms no part of the present invention and may comprise a known type of unit which is capable of being preset to count 3. predetermined number of electrical impulses and provide a suitable signal when the count is completed. One form of counter which is suitable for the present purpose and which is commercially available is the reset type of counter manufactured by the Eagle Signal Corp. and known as Model No. HZ50A6. When the clutch coil of this counter is energized, the device is conditioned for counting and each time a count coil 241 is energized and deenergized, the mechanism of the counter will be advanced one step until the desired count has been effected. Thereupon the contacts COB-1 will open thereby deenergizing relay 7CR and dropping out the clutch coil 240 to terminate the counting operation and reset the counter.

Assuming that the carriage 32 is in its home position with the limit switch 3L8 held operated by dog 64 (FIG. 3), the contacts 3LS (FIG. 10a) in line 27 will be held closed and relay 6CR will be energized upon closure of contacts 7CR in line 27. Hence, the normally open contacts 6CR in line 14 will be closed and the count coil 241 will be energized so as to condition the counter to count the first pass of the truing tool across the grinding wheel.

total amount of fine compensation entered by pushbutton PB during the grinding operation. As previously explained, this will bring the wheel slide into phase with the truing tool Since the advance of the slide will be equal to the material removed from the wheel on the first pass of the tool. In this connection it will be recalled that the amount of material removed from the wheel on the first truing pass is equal the total advance of the truing tool minus the amount of fine compensation of the wheel slide during the grinding operation.

After the advance of the coarse ratchet Wheel by pawl 171, the limit switch 4LS will be operated by pawl 179 (FIG. 8) dropping into the bottom of the next tooth space. Hence, the contacts 4LS in line 41 will close and, since contacts ISCR in this line are now closed, the relays 3TR and 4TR will be energized. The contacts 3TR in line 33 will be closed but this is of no consequence since the delay contacts 2TR in line 34 are still closed. The contacts 4TR in line 37 will open and deenergize relay 13CR thereby permitting the pawl 171 to return to its initial position. Also, the contacts 3TR in line 39 will time open and drop out relays ISCR, STR, and 4TR. Thereby, the contacts 3TR in line 33 will open and permit relay IZCR to drop out. The contacts 4TR in line 37 will time close but this will be without eifect since relay 120R has now dropped out and opened its contacts in line 37. Also, the contacts 3TR in line 39 will close and prepare relay 150R for energization on the next operation of limit switch 4LS.

When the carriage 32 moves out at the reversal position toward the home position, the timer relay 2TR will again be energized and will again drop out after the carriage returns home. Accordingly, the truing tool will again be advanced and the wheel slide will be given an increment of coarse compensation equal to the amount of diamond advance at the home position. The resulting operation of limit switch 4LS will cause energization of relays CR, 3T R and 4TR in the same manner as described above.

With the present mechanism there is a possibility, if the operator is not otherwise instructed, that the number of fine compensations entered by the pushbutton 10PB may exceed the number of steps of the fine ratchet wheel per tooth of the coarse ratchet wheel. In this case, when the sensing pawl 179 drops into the bottom of a tooth space on the coarse ratchet wheel, the timer relay 3TR will be energized and close its contacts in line 33. Diamond advance relay 12CR will thereby be energized and cause advance of the truing tool toward the grinding wheel. Since the amount of material worn from the wheel is equal to one coarse compensation which is equal to the amount of diamond advance, the diamond will again be in position to take a full cut when traversed across the wheel.

Energization of relay 12CR will cause its contacts 12CR in line 37 to close but relay 13CR will not be energized since the contacts 4TR (line 37) of timer relay 4TR are now open. This results from the energization of this relay simultaneously with relay 3TR. After a predetermined time delay, contacts 3TR in line 39 will open and deenergize relay 15CR. Contacts 15CR in line 41 will open and drop out relays 3TR and 4TR. Thus, relay 12CR will be deenergized and open its contacts in line 37 before the contacts 4TR in this line time closed. Hence, relay 13CR will not be energized and no coarse compensation of the wheel slide will take place. Accordingly, the wheel slide and diamond will again be in phase with one another just as they were at the end of the previous truing cycle.

In the foregoing description, the invention has been described in connection with one possible form or embodiment thereof and certain specific terms and language have accordingly been used herein. It is to be understood, however, that the present disclosure is illustrative rather than restrictive and that changes and modifications 14 may be resorted to without departing from the boundaries of the invention as defined by the claims which follow.

What is claimed is:

l. A device for bringing a wheel slide of a grinding machine into phase with a tool for truing a grinding wheel thereof after one or more fine incremental movements of the wheel slide independently of the truing tool comprising, selectively operable means to give the wheel slide a fine increment of advancing movement to compensate for wear of the grinding wheel during grinding operations, means to traverse the truing tool across the grinding wheel, means to give the truing tool an increment of movement towards the grinding wheel on each traverse of the tool across the wheel, actuating means to give the wheel slide a coarse increment of advancing movement each time the truing tool is advanced toward the grinding wheel, said coarse increment of movement being equal to the incremental advance of the truing tool, and means to mechanically sense the amount of incremental movement given to the wheel slide by said selectively operable means and to reduce the coarse increment of movement given to the wheel slide by said actuating means by a corresponding amount to thereby bring the wheel slide into phase with the truing tool.

2. The device of claim 1 wherein said mechanical sensing means includes a lost-motion connection between said actuating means and the wheel slide.

3. The device of claim 2 wherein said lost-motion connection is variable in accordance with the amount of incremental movement given to the wheel Slide by said selectively operable means.

4. A device for bringing a wheel slide of a grinding machine into phase with a tool for truing a grinding wheel thereof after one or more fine incremental movements of the wheel slide independently of the truing tool comprising, selectively operable means to give the wheel slide a fine increment of advancing movement to compensate for wear of the grinding wheel during grinding operations, automatic means for truing the grinding wheel including means to traverse the truing tool back and forth across the face of the grinding wheel and means to impart to the truing tool an increment of movement toward the grinding wheel on each pass of the tool thereacross, actuating means to give the wheel slide a coarse increment of advancing movement each time the truing tool is advanced toward the grinding wheel, said coarse increment of movement being equal to the incremental advance of the truing tool, and means effective on the first pass of the truing tool across the face of the grinding wheel to mechanically sense the total amount of incremental movement given to the wheel slide by said selectively operable means and to reduce the coarse increment of movement given to the wheel slide by said actuating means by a corresponding amount to thereby bring the wheel slide into phase with the truing tool.

5. The device of claim 4 including means to cause said imparting means to give the truing tool an increment of movement toward the grinding wheel whenever the movement of the wheel slide by said selectively operable means is equal to a coarse increment of movement thereof, and means rendered effective by said lastnamed means to prevent the actuating means from giving the wheel slide a coarse increment of advancing movement whereby the wheel slide and truing tool will be maintained in phase.

6. A device for bringing a Wheel slide of a grinding machine into phase with a tool for truing a grinding wheel thereof after one or more fine incremental movements of the wheel slide independently of the truing tool comprising, selectively operable means to give the wheel slide a fine increment of advancing movement to compensate for wear of the grinding wheel during grinding operations, means to impart to the truing tool an increment of movement toward the grinding wheel, actuating means to give the wheel slide a coarse increment of advancing movement each time the truing tool is advanced toward the grinding wheel, said coarse increment of movement being equal to the incremental advance of the truing tool, means to cause said imparting means to give the truing tool an increment of movement toward the grinding wheel Whenever movement of the wheel slide due to repeated operation of said selectively operable means is equal to a coarse increment of movement thereof, and means rendered effective by said last-mentioned means to prevent said actuating means from giving the wheel slide a coarse increment of advancing movement whereby the wheel slide and truing tool will be maintained in phase.

7. A device for bringing a wheel slide of a grinding machine into phase with a tool for truing a grinding wheel thereof after one or more fine incremental movements of the wheel slide independently of the truing tool comprising, a fine ratchet Wheel, a coarse ratchet wheel connected to said fine ratchet Wheel for rotation in synchronism therewith, the number of teeth on the fine ratchet wheel being equal to the number of teeth on the coarse ratchet wheel multiplied by a Whole number, feed means for advancing or retracting the wheel slide, means operatively connecting said ratchet wheels to said feed means, a feed pawl cooperating with said fine ratchet wheel, selectively operable means to oscillate said pawl through a fixed stroke to give the wheel slide a fine increment of advancing movement, a coarse feed pawl cooperating with said coarse ratchet wheel, and actuating means to oscillate said coarse feed pawl through a fixed stroke equal to one tooth space of said coarse ratchet Wheel to give the wheel slide a coarse increment of advancing movement whereby, upon operation of said coarse feed pawl, the wheel slide will be advanced a distance corresponding to the distance represented by one tooth space on said coarse ratchet wheel minus the number of fine increments of movement given the wheel slide by said selectively operable means subsequent to the next preceding operation of said coarse feed pawl.

8. The device of claim 7 including means to impart to the truing tool during wheel truing operations an increment of movement toward the grinding wheel equal to the distance moved by the wheel slide when the coarse ratchet wheel is moved through a distance of one tooth space, and means rendered effective by said imparting means to cause said actuating means to give said coarse feed pawl a stroke of movement on each advance of the truing tool.

9. The device of claim 8 including means to cause said imparting means to give the truing tool an increment of movement toward the grinding wheel whenever the movement of the wheel slide by said selectively operable means is equal to a coarse increment of movement thereof, and means rendered effective by last said-mentioned means to prevent the actuating means from giving the wheel slide a coarse increment of advancing movement whereby the wheel slide and truing tool will be maintained in phase.

References Cited in the file of this patent UNITED STATES PATENTS 2,709,877 Dall et al. June 7, 1955 2,718,101 Stuckey et al Sept. 20, 1955 2,882,649 Grove Apr. 21, 1959 2,937,639 Grove May 24, 1960