US2937639A - Autoamtic truing mechanism - Google Patents

Description

May 24, 1960 G. L. GROVE AUTOMATIC "mums MECHANISM 4 Sheets-Sheet 1 Filed Aug. 5, 1957 INVENTOR. GEORGE L. GROVE BY ZWWIM ATTORNEYS May 24, 1960 5. L. GROVE AUTOMATIC TRUINC MECHANISM 4 Sheets-Sheet 2 Filed Aug. 5, 1957 INVENTOR. GEORGE L. GROVE May 24, 1960 c. GROVE AUTOMATIC TRUING MECHANISM 4 Sheets-Sheet 3 Filed Aug. 5, 1957 IN VEN TOR.

GEORGE L. GROVE WWW AZ /%Z 99 93 QZJ Z YWMW ATTORNEYS United States Patent 1O AUTOMATIC TRUING NIECHANISM George L. Grove, Cincinnati, Ohio, assignor to The Cincinnati Milling Machine Co., Cincinnati, Ohio, :1 corporation of Ohio Filed Aug. 5, 1957, Ser. No. 676,195

7 Claims. (Cl. 125-11) 2,937,639 Patented May 24,

ICC

Fig. 5 is a cross-sectional view taken along the line- 5-5 in Fig. 3. Fig. 6 is a cross-sectional view taken along the line 6-6 in Fig. 3. V v

Fig. 7 is a wiring diagram showing the electrical control circuits for the automatic truing mechanism.

In the detailed specification to follow, similar refer ence 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 known construction to which there is shown applied the automatic truing mechanism forming the subject matter of the present invention. It is to be realized, however, that the automatic truing mechanism may 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 abase 10 upon which is supported a pair of spaced grinding wheels 11 and 12 (see Fig. 6) enclosed within a guard 13. The grinding the amount of advance of the diamond on each pass and the number of passes thereof being predetermined by the operator so that upon depression of a push button a completely automatic truing cycle can be'eifected. Thus, uniform truing of the wheel is insured, together wheels are suitably journaled in bearings supported on the base 10 and are driven by a motor (not shown) also supported on the base. A pair of correspondingly spaced regulating wheels 14 are supported on a carriage 225 15 which is mounted for sliding movement on a lower.

with an attendant saving of time since the advance of v the diamond, turning on of the coolant for each pass, and reversal of the traversing carriage at the end of each pass is' effected in a predetermined sequence and without delay.

Accordingly, it is an object of the present invention to provide a fully automatic .truing cycle for grinding machines which enables a complete truing operation to be effected by a single depression of a push button.

Another object of the invention is to provide an automatic truing mechanism in which the amount of advance of the diamond on each pass and the number of truing passes etfected by the diamond may be set into the mechanism in advance and thereby determine the character of all subsequent truing cycles.

Another object of the invention is to provide an automatic truing mechanism in which the setting of the reversal points of the traversing carriage on which the diamond is mounted also determines the .pointsat which coolant flow to the wheel will be initiated, thereby simplifying the set-up of the machine for a particular job.

Another object of the invention is to provide an automatic truing mechanism which is adaptable to the truing of a plurality of spaced grinding wheels by a single diamond, the latter being moved in rapid traverse from one slide 16 which carries a work rest blade 17 for supporting the workpiece 18. Suitable driving means is provided for rotating the regulating wheels and a power feed mechanism is customarily provided for moving the carirage and regulating wheels toward the workpiece to effect a grinding operation and to withdraw the wheels therefrom after the operation has been completed.

After a predetermined number of workpieces have been ground by the machine, it is necessary to truethe grinding wheels and, for this purpose, a diamond truing mechanism 20 has been provided. This mechanism is supported on a bracket 21 mounted on the base of the machine as shown in Fig. 1. In accordance with the present invention, the truing operation is rendered fully automatic, the operator merely selecting the number of truing passes to be made by the diamond by appropriate setting of a dial 22 on a counter 23 contained in an electrical cabinet 24. A Truing Start push button 19 is then depressed to cause the diamond to traverse back and forth across the wheels 11 and 12 with automatic advance of the diamond to remove the necessary amountof material from the wheels on each pass and thereby provide an accurate and sharp surface thereon. The means whereby this is accomplished will be described in detail in the succeeding portions of the specification.

wheel to the next so as to shorten the truing cycle to the fullest possible extent with this type of truing mechamsm.

With these and other objects in view, which will become apparent from the following description, the invention includes certain novel features of construction and combination 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 side elevation of a centerless type grinding machine to which the invention is shown applied.

Fig. 2 is a diagrammatic view of the hydraulic circuit of the machine shown in Fig. 1. p

Fig. 3 is a cross sectional elevation of the truing mechanism shown in Fig. 1.

Fig. 4 is a view showing a development of the diamond advance selector bushing shown in Fig. 5.

As shown in Fig. 3, there is secured to the upper surface of the bracket 21 a bed plate 28 which is provided with a dovetail rib 29 which cooperates with correspondingly shaped ways provided in the bottom of a carriage 30 which is provided with a flat bearing surface 31 adapted to seat upon a corresponding surface provided on the bed plate 28. The carriage will thereby be guided for rectilinear sliding movement on the bed plate 28. 1 Supported within the carriage 30 for sliding move-' ment in a direction perpendicular to that of the carriage is a slide 35 which is bored in a longitudinal direction to receive a diamond truing bar 36. The slide is sup ported for translation in the carriage 30 by means of a pair of longitudinally extending grooves disposed on either side of the slide as shown in Fig. 6 in which are seated balls 37 which are received in grooves in rails 38 suitably secured within the carriage. The slide 35 is therefore free to move in its longitudinal direction within the carriage, the balls 37 running freely in the grooves provided therefor in the slide and in the rails 38 so as .to provide an anti-friction bearing for the slide. The

diamond truing bar 36, which is of hollow tubular con struction, is supported for sliding movement within the slide 35 by means of bearing surfaces 40 and 41 pro vided at the ends of the slide. As viewed in Fig. 3, the bar 36 is secured at its left hand end to a bracket 44 which, in turn, is attached to a housing 45 which contains the diamond advancing mechanism- At its right hand end the truing bar 36 carries a diamond turner 46 of known construction which supports the truing diamond 47in position to engage the periphery of the grinding wheels 11 and 12. The wheel guard 13 is provided with an elongated opening 48 for accommodating the truing bar and permitting it to travel back and forth across the wheels. 7

The advance of the diamond toward the wheels prior to each truing pass is effected by means of a feed screw 50 which is rotatably journaled at its left hand end in the housing 45 and is held against axial movement with respect thereto by a flange 51 formed on the lead screw and a hub 52 provided on a hand wheel 53 secured to the left hand end of the lead screw. At its right hand end, the lead screw 50 threads into a collar 54 secured to the left hand end of the slide 35 whereby rotation of the lead screw will feed the truing bar 36 relative to the slide 35.

The position of the slide 35 with respect to the carriage 30 is determined by a profile cam 56, suitably secured to the bed plate 28, and a cooperating cam follower 57 fastened to the collar 54. The cam follower is maintained in contact with the profile cam 56 by means of springs (not shown) which act on the slide 35 and urge it to the right as viewed in Fig. 3. The action of the springs on the slide may be modified by manual pressure applied to a hand lever 58 secured to a stub shaft 59 journaled in the carriage 30. The shaft 59 carries an eccentrically mounted pin 60 which engages in a cross clot provided in the top of the slide 35 to provide control thereof by the hand lever.

Traversing movement of the carriage 30 on the bed plate 28 is effected by means of a lead screw 63 supported at its ends in the plate 28 and meshing with a nut 64 mounted in the carriage 30. The lead screw is driven by a hydraulic motor which will be described in connection with the hydraulic diagram in a later portion of this specification.

As shown in Figs. 3 and 6, the carriage has mounted on its forward end an elongated bar 66 on the opposite ends of which are mounted dogs 67 and 68 which are adjustable along the length of the bar and which may be clamped in adjusted position by means of bolts 69, the heads of which are received in a T slot 70 (Fig. 3) provided in the bar 66. The dog 67 is adapted to cooperate with the contact roll 71 of a limit switch 2LS while the dog 68 is adapted to cooperate with the roll 72 of a limit switch 3L5. These limit switches, together with a third limit switch LS, are supported in a housing 75 carried by the wheel guard 13. Intermediate the dogs 67 and 68 there is secured to the bar a rapid traverse cam 73 which is adapted to cooperate with the contact roll 74 of the limit switch SLS.

Advance of the diamond truing bar 36 may be effected either manually by means of the hand wheel 53 or automatically by means of a pawl and ratchet mechanism driven by a feed piston 80. As shown in Figs. 3 and 5, the piston 80 is slidably received within a cylinder 81 provided in the lower portion of the housing 45. As shown in Fig. 5, the right hand end of the cylinder is closed by a cap 82 suitably secured to the housing, while the left hand end of the cylinder is closed by a bushing 83 which is adjustably secured to the housing 45 by cap screws 84 and set screws 85. The bushing 83 is provided with an axial bore for receiving the stem 86 of a diamond advance selector knob 87 which may be turned to any one of four positions to provide different amounts of diamond advance. As shown in Fig. 5, the right hand end of the stem 86 serves as a stop to limit left hand movement of the piston while the cap 82 serves as a stop to limit right hand movement of the piston within the cylinder. The piston is bored to receive a compression spring 88 which presses on the stem 86 and thereby urges a pin 89 projecting radially from the stern into engagement with the inner edge of the bushing 83.

As more clearly indicated in Fig. 4, the edge of the bushing 83 is provided with four notches 90 of varying depth for receiving the pin 89. Hence, by pressing in on the knob 87 and turning the same, any one of the notches 90 may be selected to receive the pin 89, thereby providing four different degrees of adjustment of the inner end of the stem 86 relative to the left hand end of piston 80. Thus, for diflferent strokes of movement are permitted the piston, which strokes are effected under hydraulic pressure controlled by a valve located in the bottom of the housing 45. This valve includes a spool 93 (Fig. 5) which is slidable in a cylindrical bore provided in the base of the housing and which is urged toward the right by a compression spring 94. The spool is thereby maintained with its right hand end bearing against the inner edge of a bushing 95 located in the end of the cylindrical bore. An intermediate portion of the bore is connected by a channel 96 with the right hand end of the cylinder 81. When the spool 93 is in the position shown in Fig. 5, this channel is communicatively connected with an exhaust line 97, thereby permitting the spring 88 to move the piston 80 to the limit of its movement in the right hand direction. However, when solenoid 6SOL is energized, a plunger 98 passing through a bore in the bushing 95 will be projected outwardly against the right hand end of the spool 93 and shift the latter to the left against the force of the spring 94. With the spool in this position, the channel 96 will be communicatively connected with a pressure line 99 whereby hydraulic fluid under pressure will be admitted to the right hand end of the cylinder 81 thereby driving the piston 80 to the left. When the solenoid is deenergized, the spring 94 will return the spool to the position shown in Fig. 5 thereby again connecting the right hand end of the cylinder 81 with the exhaust line 97 whereupon the spring 88 will return the piston to the position shown in Fig. 5. As heretofore mentioned, the stroke of the piston is determined by the setting of the selector knob 87 so that different degrees of advance of the diamond may be obtained.

As herein shown, the upper edge of the piston 80 is provided with rack teeth which mesh with the teeth of a spur gear 100, the upper portion of which is removed to provide a seat for a block 101 which is screwed fast to the gear. Situated adjacent the gear 100, which is freely rotatable on the feed screw 50, is a ratchet wheel 102 which is pinned to the screw 50 as indicated'in Fig. 3. The wheel 102 is arranged to be driven by a pawl 103, which is pivoted on a stud 104 carried by the block 101 and is urged by acompression spring 105, interposed between the block and the pawl, in a clockwise direction about the stud 104 to engage the pawl with the teeth of the ratchet wheel 102. Hence, when the piston 80 is driven to the left as viewed in Fig. 5 thereby turning the gear clockwise, the pawl 103 will turn the ratchet Wheel 102 and the lead screw 50 in a similar direction. When the piston 80 returns to the right, thereby driving the gear 100 in a counterclockwise direction, the pawl 103 will ratchet over the teeth of the wheel 102 and the feed screw 50 will remain stationary. Depending on the setting of the selector knob 87, the ratchet wheel will be advanced through a distance of one, two, three, or four teeth thereof and cause corresponding amounts of diamond advance.

To permit manual operation of the feed screw 50 in either direction by the handwheel 53, an Auto-Manual selector knob 108 is provided on the side of the housing 45. This knob is adapted to rotate a hub 109 carrying an ecc'entrically mounted lug 110 which underlies the right hand end of the pawl 103. Hence, when the knob 108 is turned 180 degrees, the lug 110 will elevate the pawl and disengage it from the teeth of the ratchet wheel 102. At the same time, the upper edge of the pawl will engage the plunger of a limit switch 4LS mounted on a bracket in the top of the housing 45 and, through means hereinafter to be described, will thereby disable the automatic truing control circuit.

. As hereinbefore-stated, the diamond turner 46 (Fig. 3) is of conventional design and is adapted to be operated by hydraulic fluid under pressure admitted through a coupling 115 to the interior of a tube 116 by which it is transmitted through the truing bar 36 to the diamond turner 46. The construction of the turner 46 is such that when pressure is admitted to the tube 116 the diamond 47 will be turned, and upon a drop of pressure within the tube 116, the diamond turning mechanism will be reset ready for the next operation.

The hydraulic control circuit for the automatic truing mechanism is shown in Fig. 2 of the drawings. As therein indicated, fluid under pressure is delivered to the pressure line 99 by a hydraulic pump 120 driven by an electric motor (not shown). The pump draws fluid out of a sump or reservoir 121 for delivery to the pressure line 99in which the fluid is maintained under constant pres sure by a relief valve 122 which discharges excess fluid into the reservoir 121. The exhaust line 97 returns fluid to the reservoir from the various hydraulic components contained in the circuit.

As heretofore mentioned, the feed screw 63 (Figs. 2 and 3), which traverses the carriage 30 back and forth with respect to the grinding wheels 11 and 12, is driven by a hydraulic motor which is indicated in Fig. 2 by reference numeral 125. This motor is connected by hydraulic lines 126 and 127 to a reversing valve 128. This valve is controlled by a solenoid operated pilot valve 129 which valves fluid under pressure to the ends of valve 128 through lines 130 and 131, thereby shifting the latter valve in one direction or the other. The pilot valve 129 contains a spool 132 which is held in a centered position within the valve body by means of compression springs 133 and centralizing washers 134. The valve is provided with a centrally located pressure port which is connected to the pressureline 99, and with a pair of exhaust ports located on opposite sides of the pressure port which are connected with the exhaust line 97 through a check valve 135 and suitable lines connecting the ports with the check valve. Hence, when the solenoid 3SOL is energized, the spool 132 will be shifted to the left, as viewed in Fig. 2 thereby connecting the line 130 with the pressure line 99, and the line 131 with the exhaust line 97. This will cause pressure to be applied to the left hand end of the reversing valve 128 and will connect the right hand end of this valve with the exhaust line 97. As a result, a spool 138 which is normally held in acentered position by compression springs 139 and centralizing washers 140, will be shifted to the right thereby opening pressure from a port 141 connected with pressure line 99 to the motor line 127 and connecting motor line 126 with an exhaust port 142 connected to areturn line 143. The motor 125 will thereby be rotated in adirection to drive the carriage 30 away from home position, i.e., the position in which dog 67 (Fig. 6) is in, contact with roll 71. g the solenoid 4SOL is energized, the spool 132 will be shifted to the right to cause spool 138 to be shifted to the left, thereby opening a pressure port 144 to the motor line 126 and connecting the return port 142 to the motor line 127. This will cause the motor 125 to rotate in the opposite direction and move the carriage 30 from a reversal position, as represented by engagement of the dog 68 with the contact roll 72 (Fig. 6), toward home positionfurther shown in Fig. 2, the return line 143 is con- If, on the other hand,

nected by line 145 with a pressure reducing valveJ146; This valve contains a sliding plunger 147 containing a transverse bore 148 and alongitudinal bore 149 cornmunicatively connected therewith. The bore 149 extends to the bottom of the plunger 147 and transmits fluid to a chamber 150 provided'in the bottom of the valve. The pressure of the fluid in the chamber 150 will tend to raise the plunger 147 against the urgency of a compression spring 151 acting downwardly on the top of theplunger, this upward movement of the plunger tending to cut 011 the port to which line 145 is connected. Accordingly, the pressure will be-stabilized when the pressure in the chamber 150 equals the pressure acting on the top of the plunger through spring 151 and fluid under constant pressure admitted to the top of the valve through a line 152. Since the downward force acting on the plunger is constant, the pressure in chamber 150 will also remain constant, and a constant pressure will thereby be maintained at the outlet port 153. This port is connected by a line 154 with a rate valve 155 which may be adjusted by rotating a knob 156 to vary the amount of oil permitted to fiow throughan outlet port 157 on the valve. This port is connected by a line 158 with a relief valve 159 which is connected by a line 160 with the exhaust line 97. The pressure in the line 158 will thereby be maintained constant at the setting of the relief valve 159 whereby the oil admitted through line 152 to the top of the pressure reducing valve 146 also will be'maintained constant. The pressure thereby provided on top of the plunger 147 will assist the spring 151 and provide more linear operation of the pressure reducing valve. Hence, by suitable adjustment of the rate valve 155, through manipulation of knob 156, the feed rate of the diamond across the grinding wheels may be adjusted as desired.

To provide for rapid traverse of the diamond from one grinding wheel to the next, a rapid traverse valve is provided for by-passing the rate valve and con-' necting the return line 145 directly to the exhaust line 97. This valve is provided with a spool 166 which is normally held in its left hand position as shown in Fig. 2 by compression spring 167. In this position of the spool, a line 168 connected to the return line 143 is blocked by a land on the spool. However, when a solenoid SSOL is energized, the plunger 166 will be moved to the right against the urgency of spring 167, and. the line 168 will bev communicatively connected with the exhaust line 97, thereby bypassing the rate valve and permitting the motor 125 to run at full speed. The present invention includes means for utilizing the shifting of the reversing valve 128 for initiating the flow of coolant to the truing device so as to flood the diamond and the wheel with coolant during the truing operation. Thus, regardless of the stroke of the carriage as determined by the adjustment of the dogs 67 and 68 (Fig. 6), coolant flow will always be initiated at the beginning of the truing pass and will be terminated at the end of the pass. This feature eliminates the necessity of setting individual stops to control coolant flow in addition to the reversing dogs 67 and 68. As shown in Fig. 2, the reversing valve 128 is provided with a pair of ports 1'70 and 171 which are connected by lines 172 and 173 with the actuating cylinder of a coolant control valve 174. When the spool 138 is in its centered position, as shown in Fig. 2, the ports and 171 are in com munication with ports 175 and 176 which are connected to the exhaust line 97 through a line 177 and a check valve 178. However, whenever the reversing valve is shifted in either direction, one of the ports 170 and 171' will be connected to a pressure port 141 or 144 while the remaining port will be blocked off by lands formedon the ends of the spool 138. Hence, shifting of the reversing valve will cause pressure to be applied to the chamber 179 of control valve 174 which lies beneath a plunger 1800f the valve. This will cause the plunger. to be raised against the force exerted by a. springlQL and permit a diaphragm 182 to be lifted off a port 183 by the pressure of coolant flowing in through a line 184. The coolant will thereby be permitted to flow into an annular groove 185 provided in the base of the valve and out through a line 186 to the truing bar 36 (see also Fig. 3). It then passes through the space existing between the interior wall of bar 36 and the exterior wall of the tube 116 to a coolant discharge pipe 187 mounted on the end of the truing bar as shown in Fig. 2. When the valve 128 is again centered to terminate traversing movement of the diamond carriage, pressure will be removed from the lines 172 and 173, and the spring 181 will cause the bottom of the plunger 180 to press against thediaphragm 182 and seal off the port 183.

At the same time that pressure is delivered to the coolant valve 174, a portion of the fluid flowing through the line 172 is carried by a line 183 to the coupling 115 (see also Fig. 3) to provide pressure for operating the diamond turner 46.

The electrical control circuits for the automatic truing mechanism are shown in the wiring diagram (Fig. 7). Energy for the control circuit is provided by a transformer 195 which energizes lines 196 and 197. Accordingly, when the Start push button is depressed in line 3 of the diagram, the relay LEA will be energized to start the electric motor which drives the hydraulic pump 120 (Fig. 2). At the same time the contacts LEA in line 4 will be closed around the Start push button so as to lock in the relay and hold it energized after the push button is released. A pressure switch 1-PS, shown in line 5 of the diagram, is provided for insuring that pressure lubricant is supplied to the grinding wheel spindle before the grinding wheel motor may be started. Assuming this switch to be closed, line 198 will be now connected to line 196 so that depression of the Grinding Wheel Start push button in line 6 will energize a relay LED which, through suitable contacts not shown, energizes the grinding wheel motor. At the same time, a pair of contacts LED of this relay, shown in line 7, will be closed around the push button to maintain the relay energized. The machine will now be conditioned for the commencement of an automatic truing cycle, the closed contacts LED being effective to connect a line 199 with the now energized line198.

To start an automatic truing cycle, the Truing Start push button 19 in line 9 is depressed, thereby energizing the clutch coil 200 of the counter 23 (Fig. 1), the coil being maintained energized by the contacts 7CR (line 10) of a relay 7CR (line 24) which is energized by closure of contacts COB. The contacts COB are provided on the counter and remain closed so long as the clutch coil 200 is energized.

As heretofore mentioned, the counter controls the number of passes of the diamond across the face of the grinding wheel. The counter per se forms no part of the present invention and may be any type of device which is capable of being preset to count a predetermined number of electrical impulses and to provide a suitable signal when the count is completed. One form of counter which is especially suitable for the present purpose and which is commercially available is the reset type of counter manufactured by the Eagle Signal Corporation 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 201 (line 11) is energized and dcenergized, the mechanism of the counter will be advanced one step until the desired count has been effected, whereupon the contacts COB (line 24) will open upon the deenergization of coil 201, thereby deenergizing relay 7CR and dropping out the clutch coil 200 to terminate the counting operation and reset the counter for the next operation.

Assuming now that the carriage 30 is in its home position with the limit switch 2LS operated by dog 67, the contacts 2LS in line 23 will thereby be held closed and relay 60R will be energized upon closure of contacts 7CR in line 23. Hence, the normally open contacts 6CR in the line 12 will be closed, and the count coil 201 will be energized so as to condition the counter to count the first pass of the diamond across the wheels. At the same time, the normally open contacts of 6CR in line 13 and 15 will also be closed, thereby causing relay 3CR to be energized through the normally closed contacts 2TR (line 15) of timer relay 2TR and limit switch contacts 3L5 (line 13). It will be noted that relay 3CR will be locked in around the contacts of relay 6CR in lines 13 and 15 by the contacts 3CR in lines 14 and 16. The .contacts 3CR in line 26 will thus be closed, thereby energizing solenoid SSOL which will shift the spool 132 (Fig. 2) of pilot valve 129 to the left and operate the reversing valve 128 to cause the carriage to move away from home position and coolant to flow over the diamond.

As the carriage moves out of home position at the feed rate determined by the setting of the rate valve 155, the limit switch ZLS will be released thereby deenergizing relay 6CR (line 23) and the count coil 201 to enter the first count in the counter. At the same time, the contacts 2L8 in line 25 will be closed, thereby energizing relay 8CR and causing the contacts of this relay in line 32 to close. As the carriage moves to the left, as viewed in Fig. 6, the rise on cam 73 will operate limit switch SLS after the doamond has finished truing the wheel 12. This will cause the contacts of this limit switch in line 32 to close, thereby energizing SSOL and operating the rapid traverse valve 165 (Fig. 2) to bypass the rate valve and cause rapid traverse of the carriage. Rapid movement of the carriage will continue until the roll of limit switch 5LS leaves the high portion of the cam as the diamond approaches the wheel. The limit switch will thereupon be released and SSOL deenergizcd to reintroduce the rate valve into the circuit and reduce the rate of travel of the carriage to a normal feed rate.

When the reversing dog 68 strikes the contact roll 72 of limit switch 3LS, the contacts of this limit switch in line 22 will be closed, thereby energizing relay 5CR. This will cause the normally open contacts of this relay in line 11 to close, thereby again energizing the count coil 201 and preparing the counter for the next count. Also, the contacts 3LS in line 13 will open, thereby deenergizing 3CR. This will open the contacts 3CR in lines 16 and 26 so as to drop out timer relay 3TR and deenergize solenoid 3SOL. When relay 3TR is dropped out, solenoid 6SOL will be energized by the instantaneous closing of contacts 3TR-2 of the relay in line 33 and the timed opening of the delay contacts 3TR-3 also in this line. The solenoid 6SOL will thereby be maintained energized from the time relay 3TR is deenergized until the delay contacts 3TR-3 time open. The valve spool 93 (Fig. 5) will thereby be operated to move the piston and advance the diamond by the amount determined by the setting of the selector knob.

The timer relay 3TR has a second pair of delay con tacts shown in line 20 which will time closed when the relay is deenergized. When these contacts close, relay 4CR will be energized, the contacts SCR in line 19 and 8CR in line 13 being closed at this time. Relay 4CR will be locked in around the SCR and 3TR contacts by the contacts 4CR in line 21. Energization of relay 4CR will reenergize relay 3TR by closing contacts 4CR in line 17.

After the contacts 3TR in line 20 have timed closed to energize relay 4CR, the contacts 4CR in line 30 will close and energize solenoid 4SOL to move the slide away from the reversal position and toward the home position with flow of coolant to the diamond. As the slide leaves the reversal point, the dog 68 will release limit switch 3L8, thereby opening the contacts 3LS in line 22 to deenergize relay SCR and complete the second count. At the same time, the contacts 3LS in line 13 will close to energize timer relay 2TR.

After the wheel 11 has been trued (Fig. 6), the cam 73 will operate limit switch L8 to cause rapid traverse of the diamond to the second wheel 12.- The wheel 12 will then be trued at a normal feed rate after which limit switch 2LS will be operated by the dog 67. This will open the contacts 2LS in line 25 and close thecontacts 2LS in line 23, thereby deenergizing relay 8CR and energizing relay 6CR to energize co'il 201 and condition the counter for the third count. When relay 8CR is deenergized, relays ZTR, 3TR and 4CR will drop out, thereby permitting contacts 2TR in line 15 to time closed and contact 3TR-3 in line 33 to time open. Since the contacts 3TR-2 are now closed, the solenoid 6SOL will be energized to provide diamond advance. As soon as the contacts 2TR (line 15) time closed, the relay 3CR will be energized since the contacts 6CR in lines 13 and 15 are now closed. The relay 3TR will now be energized to deenergize solenoid 6SOL and to open its contacts in line 20. When the relay 3CR is energized, its contacts in line 26 will be closed, thereby energizing solenoid 3SOL to move the slide away from home position for the next pass and turning on the coolant.

It will be noted that if the counter counts out in the home position of the carriage, the contacts COB will open to deenergize relays 7CR and 6CR. This will occur, however, after relay 3CR is energized to lock itself in aro'und the contacts of relay 6CR. Therefore, the carriage will move away from home position and continue to the reversal position. At this position relay 30R will drop out but the contacts 7CR in line 18 will be closed so that timer relay STR will not drop out to thereby energize solenoid 6SOL so that no advance of the diamond will take place. Hence, the last pass from the reversal point to the home position will be a dead pass. Since the first step of the counter takes place in the home position at the beginning of the truing operation, an odd count set up on the counter will cause the last pass to be a dead one while an even count, i.e., when the counter counts out with the slide in the reversal position will cause the last pass to be a cut pass. Thus, the operator can select at will either type of operation by setting up on the counter either an odd or an even count.

When the carriage arrives in home position after the counter has counted out, the relay 6CR will not be energized due to the open contacts 7CR in line 23, and relay 3CR will not be energized. Therefore, the carriage will stop in home position, and the truing cycle will be concluded.

A manual truing operation may be performed by manipulation of the Auto-Manual selector knob 108 (Fig. 5) which operates limit switch 4LS. In this case, the contacts 4LS in line 13' (Fig. 7) will be open, thereby deenergizing the automatic truing control circuit. With a manual setting of the knob 108, the carriage may be moved away from home by moving the switch 202 (line 28) to the Out position. This will cause solenoid 3SOL to be energized since the contacts 4LS in line 28 are now closed. If it is desired to move the carriage to'ward home position, the selector switch 202 is turned to the In position whereby solenoid 4SOL will be energized. Rapid traverse of the cross slide may be selected in manual operation by depression of the puth button switch 203 (line 31) which energizes solenoid SSOL, thereby bypassing "the rate valve and permitting the hydraulic motor 125 (Fig. 2) to run at full speed.

The manual control provided by the Auto-Manual selector knob 108 is useful in setting up a job and preparing the machine for a fully automatic truing operation. With the knob 108 set to Manual position, the diamond may be backed away from the grinding wheels by manipulation of the hand wheel 53. The selector switch 202 (Fig. 7) is then turned to the Out position to move the carriage away from home position. The rate valve 155 (Fig. 2) is now adjusted to provide the desired feed rate of the carriage for truing of the wheels. After the diamond has cleared the second wheel, the carriage is 10 stopped by turning switch 202 to the Stop position, and the dog 68 is then adjusted to a point where it just oper ates the roll 72 of limit switch 3L8. The switch 202is now turned to the In position to return the carriage-to home position. The carriage is stopped in home position truing pass. The Auto-Manual selector knob'108 is no'w turned to the Auto position, and the truing mechanism is now ready for an automatic cycle which may be initiated by depressing the Turing Start push button shown in line 9 of Fig. 7. I g t Having thus described the invention in connection with one possible form or embodiment thereof and having used, therefore, certain specific terms and language therein, it is to be understood that the present disclosure is illustrative rather than restrictive and that changes and modifications may be resorted to without departing from the spirit of the invention or the scope of the claims which follow.

I claim:

1. In a grinding machine having a base, a grinding wheel supported on said base, and a source of power for driving said wheel, the combination of a carriage mounted on said base for movement thereon in a direction parallel to the axis of rotation of said wheel, a slide supported on said carriage for movement at right angles to the direction of movement of said carriage, a wheel truing unit supported on said slide for movement toward the peripheral face of said grinding wheel, means for automatically traversing said carriage back and forth on said base between a home position and a reversal position, means for advancing the truing bar by a predetermined amount each time the carriage arrives at the home position and the reversal position, means for counting a predetermined number of passes of the truing bar across the peripheral face of said wheel, and means controlled by said counting means for preventing the automatic ad vance of the truing bar in the next reversal position of the carriage when said counting means has counted out in the preceding home position thereof.

2. In a grinding machine having a base, a grinding wheel supported on said base and a source of power for driving said wheel, the combination of a carriage mounted on said base for movement thereon in a direction parallel to the axis of said wheel, 'a wheel truing unit mounted on said carriage, a hydraulic motor for driving said carriage, a reversing valve for controlling the operation of said motor, and means controlled by said reversing valve for causing coolant to be delivered to the grinding wheel during each, traversal of the truing unit across the face of said wheel.

3. The grinding machine of claim 2 wherein said lastnamed means includes a coolant control valve, and means operatively connected with said reversing valve for operating said coolant control valve.

4. In a grinding machine having a base, a grinding wheel supported on said base and a source of power for driving said wheel, the combination o'f a carriage mounted on said base for movement thereon in a direction parallel to the axis of rotation of said wheel, a wheel truing unit on said carriage, means for automatically traversing said carriage and said unit back and forth on said base between a home positio'n and a reversal position, said traversing means including a hydraulic motor for moving the carriage, a reversing valve for controlling the operation of said motor, and means moving with said carriage for initiating the reversal of said valve when the carriage moves into its home position and into its reversal position, and means controlled by said reversing valve for 11 causing coolant to be delivered to the grinding wheel during each traversal of the truing unit across the face of said wheel.

5. The grinding machine of claim 4 wherein said lastnamed means includes a coolant control valve, and means for causing said co'olant control valve to be operated to deliver coolant to the grinding wheel upon each reversal of said reversing valve.

6. In a grinding machine having a base, a grinding wheel supported on said base and a source of power for driving said wheel, the combination of a carriage mounted on said base for movement thereof in a direction parallel to the axis of rotation of said wheel, a slide supported on said carriage for movement at right angles to the direction of movement of said carriage, a wheel truing unit supported on said slide for movement toward the peripheral face of said grinding wheel, means for automatically traversing said carriage back and forth on said base between a home position and a reversal position, and means for advancing the truing unit by a predetermined amount each time the carriage arrives at the home position and at the reversal position, said advancing means including a solenoid, an energizing circuit for said solenoid, and a timer relay having a pair of instantaneous contacts and a pair of time delay contacts connected in series with said solenoid across said energizing circuit for first energizing said solenoid and then dcenergizing said solenoid after a suitable time delay.

7. The grinding machine of claim 6 including means for counting a predetermined number of passes of the truing unit across the peripheral face of said grinding wheel, and means controlled by said counting means for preventing the energization of said solenoid in a reversal position of said carriage after said counting means has counted out in a preceding home position thereo'f.

References Cited in the file of this patent UNITED STATES PATENTS 1,976,123 Haas Oct. 9, 1934 1,976,124 Haas Oct. 9, 1934 2,522,485 Silven Sept. 12, 1950 2,759,304 Silven et al. Aug. 21, 1956

Images