US1934601A - Grinding machine - Google Patents

Description

Nov. 7, 1933. F. v. GEIER ErAL 1,934,601

GRINDING MACHINE Filed Dec. l5, 1931 6 Sheets-Sheet l @www 4 www@ Nov. 7, 1933. F. v. GEIER `Er AL 1,934,601

GRINDING MACHINE Filed Dec. l5, 1931 Y 6 Sheets-Sheet 2 lag? NOV-- 7, 1933. l. F v..GE|ER Er AL 1,934,601

GRINDING MACHINE Filed nec. `15, 1931 s sheets-sheet 5 o /J/ K jj? my a3, MMM,

Nov. 7, 1933. F. v, GEH- :R Er AL 1,934,601

GRINDING MACHINE Filed Deo. l5, 1931 6 Sheets-Sheet -4 m (\l LOW is@ NOV- 7, 1933 F. v. GEIE-R ErAl. 1,934,601

GRINDING MACHINE Filed Dec. l5, 1931 6 Sheets-Sheet 5 W l W Nov. 7, 1933. F. v. GEIER Er AL GRINDING MACHINE l5. 1931 6 Sheets-Sheet 6 Filed Dec.

Patented Nov. 7, 1933 GRINDING MACHINE Frederick V. Geier and Frederick S. Haas, Cincinnati, Ohio, assignors, by mesne to The Heald Machine Company,

assignments, Worcester,

Mass., a'corporation of Massachusetts Application December 15, 1931 Serial No. 581,192

11 Claims.

cision machine tools, it

is of utmost importance that the cutting elements or grinding tools be at all times in a free, clean cutting condition. To maintain this condition of the tools, it is necessary to redress the same at definite stated intervals.

However, the normal production of the machine must not be materially interfered with during the truing operation, particularly in high production machines which are in continuous or constant use. It is, therefore, one of the principal objects of the present invention to provide an improved operating cycle for high production grinding machines truing or redressing having coupled therein a remechanism.

Another object of the invention is the provision of improved means for periodically, cyclically redressing the operative face of the grinding wheel during or while the several parts thereof are being brought into an A further object of the operative relationship.

invention is the provision of an improved mechanism which definitely insures the proper relationship of the parts and thereby prevents any interference between the several shiftable units of the machine.

A still further object of the invention is the provision of an interlock between the mechanism that projects the truing tool into, and retracts the truing tool from, the path of movement of the grinding wheel to tion of the truingdtool the other parts of the insure the retracbefore the operation of machine.

Other objects and advantages of the present invention should be readily apparent by reference to the following specication considered in conjunction with the accompanying drawings it is to be understood be made in the exact structural details there shown and described within the scope of the appended claims without departing from or`exceeding the spirit of the invention.

In the drawings:

Figure 1 is a front elevation of a grinding machine embodying the improvements of this invention.

Figure 3 is a plan view of a portion of Figure 1,

certain parts being shown in cross section as particularly seen from line 3-3 thereon.

Figure 4 is a sectional View along the line 4-4 of Figure 3. d

Figure 5 is a sectional view along the line 5-5 of Figure 1.

Figure 6 is a sectional view along the plane adjacent to the plane of Figure 5.

Figure 7 is a sectional view along the line 7-7 of Figure 2.

Figure 8 is a sectional view along the line 8-8 of Figure 7.

Figure 9 is a sectional view along the line 9-9 of Figure 2. Figure 10 is a sectional view along the line 10--10 of Figure 9.

Figure 11 is a sectional View along the line 11-11 of Figure 9.

'Figure 12 is a sectional view of one of the switches shown in Figure 2 and forming a detail of the invention.

Figure 13 is a diagrammatic view illustrating the hydrauilc and electrical circuits involved in this invention.

Figure 14 is a sectional View on line 14-14 of Figure 2.

Figure 15 is a sectional view along the line 15-15 of Figure 3.

Throughout the several views of the drawings similar reference characters are employed to denote the same or similar parts.

For the purpose of illustration and description the invention has been shown in the drawings as applied to an internal grinding machine or hole generator. The machine may comprise a bed 15 having formed on the upper surface thereof, in spaced parallel planes, ways 16 and 17. Supported on the ways 17 for guidance thereby is a wheel head 18 having a prime mover or motor 19 for rotation of a spindle 2O which carries a small diameter or internal grinding wheel 21. The said wheel head 18 is adapted to be reciprocated by an hydraulic medium normally contained in a tank `or sump 22, Fig. 13, and drawn therefrom through a conduit 23 by a pump 24. The medium is discharged from the pump under pressure through a conduit 25 to a reversing valve casing 26. Reciprocable through the valve casing 26 is a valve 27 for directing the medium selectively through either conduit 28 or 29.` As shown in Figure 13, the medium passes from the casing 26 through the conduit 28 to the right hand side of a cylinder 30 for actuating a piston 31 contained therein. The medium is dischargedfrom the cylinder ahead of the piston through the conduit 29 to be directed through conduit 32 to a casing 33 containing a start and stop valve 34, which directs the medium through a conduit 35 to the sump or tank 22.

The reversing valve 27 has extending therefrom, a valve stem 36, Fig. 1, coupled with a rock shaft 37 on which is mounted a lever 38 for manual shifting movement of the valve 27. The lever 38 is positioned between and oscillated by the opposed abutting faces of reversing dogs 39 and 40 adjustably mounted in a T-slot 41 formed in the forward face of base plate or carriage 42 for the Wheel head 18. The shifting movement of the piston 31 is transmitted through a piston rod 43 connected with the said base plate 42. The wheel head is thus reciprocated longitudinally of the ways, as above noted, by the hydraulic medium which enters either one side or the other of the cylinder 30 as directed thereto by the valve 27, the latter being controlled by the shifting of said lever 38 upon alternate engagement of the reversing lever with the reversing dogs 39 and 40.

Supported and guided by the ways 16 is a longitudinally movable slide 44 having a dove-tailed guide 45 extending therefrom and received in a similarly shaped guideway 46 formed on the underside of a cross-slide 47 which supports the work head 47. The work head 47 comprises a Work supporting blade 48, Fig. 14, having an angularly inclined top 49 peripherally supporting a work piece 50, said top 49 being inclined downwardly toward a rotatable member 51 (see also Fig. 3), secured to a spindle 52 mounted in suitable anti-friction bearings 53 carried by the cross-slide 47. The rotatable member or regulating wheel 51 is preferably constructed of suitable abrasive or frictional material for engagement with the outer periphery of the work piece 50 and by rotation of said wheel for controlling the rate of rotation of said work piece. The regulating wheel spindle and regulating Wheel are rotated at a slow rate of speed through a worm gear 54 on the spindle 52 which is engaged by a worm 55 on a vertical shaft 56, the latter being journaled in a depending portion (not shown) of the cross-slide 47 interiorly of the bed 15. This driving of the regulating wheel forms, of itself, no particular part of this invention and is fully disclosed in the copending application of Einstein, Booth and Haas, Serial Number 374,556, led June 28, 1929.

The cross-slide 47 also supports, in opposition to the regulating wheel 51, a pressure roller 57 positioned for urging the work piece toward the regulating wheel and downwardly into the supporting trough defined by the Work rest and regulating wheel. The pressure roller is supported by a bracket 58 which is adjustably secured to the cross-slide by bolts 59. This bracket has bearings 60, Fig. 15, for a bushing or sleeve 61 on which is secured a yoke 62 provided with antifriction bearings 63 for a spindle 64 to which the pressure roller 57 is secured. The pressure roller, as shown in Fig. 15, has its axis permanently disposed at an angle to the horizontal or general plane of the machine. The specific mounting of the pressure roller is similar to that fully disclosed in the above entitled copending application Serial No. 374,556.

In the normal operation' of the machine, the regulating wheel 51 is rotated in a counter-clockwise direction, as viewed in Figure 3, with the surface of said wheel which is in contact with the work piece moving downwardly, and as so rotated its outer surface engages the outer surface of the work piece 50 and procures rotation of said Work piece therewith, with the work piece moving in a clockwise direction, with the surface of said work piece which is in contact with the pressure roller moving upwardly. The pressure roller 57,. which is mounted for free rotation on the bearings 63, holds the work piece firmly against the regulating wheel while at the same time the angular disposition of the pressure roller causes it to exert an axial feeding component or thrust on the work piece, thereby urging said work piece against a back or axial thrust plate 66.

The bushing or sleeve 61 is arranged to be rocked for withdrawal of the pressure wheel out of engagement with the work piece and for returning said pressure wheel into engagement with a Work piece and to this end said sleeve is provided with a collar 67, Figs. 3 and 15, having an arm 68 which extends through a cylindrical passage in a cylinder 69, the latter containing a piston 70 diagrammatically shown in Fig. 13. This mechanism is not, of itself, the invention in the present application and will not be described in detail herein; it is sucient to note for the purposes of the present application that the piston 70 during its movement tothe left, Fig. 13, procures rocking movement of the sleeve 6l to space the pressure wheel from the work piece, said wheel being returned into engagement with a work piece upon return of the piston toward the right. The piston 70 is automatically actuated at the proper time in the grinding cycle as will appear hereinafter.

The cross-slide 47 also has mounted thereon a size controlling mechanism o f the type fully clisclosed in the above noted application Serial No. 374,556, and this mechanism comprises a housing 71 having depending therefrom a cylindrical stud 72, Fig. 4, projecting through an opening in the cross-slide 47' whereby said housing may be adjusted relative to the cross-slide 47' and clamped in adjusted position by means of nut and bolt 73 carried by said stud. The housing 71 has longitudinally journaled therein a shaft 74 provided with an arm 75 carrying a diamond point or the like 76 for engagement with the inner surface of the work piece, as shown in Fig. 3. In use this member is adjusted into such position with respect to the surface of the regulating wheel exteriorly engaging the work piece that when the inner surface of the work piece has been ground away a prescribed amount, the point 76 will just ride over the work piece in an arcuate path tangent to the inner generated surface. At the inception of the grinding operation, the shaft 74 carrying the arm and point 76 is rocked in order to position said arm 75 above its center position. A plunger 77 upwardly urged by a spring, not shown, engages an elongated pinion 78 on shaft 74, and the upward shifting of the plunger rocks the shaft 74 to cause the point 76 to swing downwardly against the work piece, interengagement of the point 76 and surface of the work piece preventing said arm from swinging past the center line of the work piece until said work piece has been ground down to correct size.

The shaft 74 is provided with a cam 79 which is effective upon a contact member 80 of a switch mechanism 81 closing the electrical control circuit 82, Fig. 13, for initiating movement of the work supporting unit and cross-slide 47 rearwardly of the grinding position. Closing of switch 81 also initiates a movement of the slide 44 longitudinally of the bed to withdraw the work piece in an axial direction away from the grinding wheel unit until the grinding wheel and work4 piece are in spaced relation. As Ithe slide 44 carrying the work controlling unit is retracted an adjustable dog 83 thereon contacts with the trip arm 84. which through a link 85 transmits -motion to a suitable member for closing a switch 86, diagrammatically shown in Figure 13, for completing an electrical circuit 87 which includes a solenoid 88 for shifting a reversing valve 89 contained in valve casing 90. Fluid .under pressure is directed to the valve 89 from the pressure line 25 through a branch conduit 91 and the valve 89, upon being shifted by the energization of the solenoid 88, directs the pressure through a conduit 92 to the left hand side of the piston 70. The medium ahead of the piston 70 is discharged through branch conduit 93 to the valve casing 90 where it is connected with the discharge conduit 94 for directing the medium to the tank or sump 22. As fully disclosed in the above noted application Serial No. 374,556, this movement of theY piston 70 causes an ejector arm 92', Fig. 1, mounted on the yoke 62 to move downwardly for engagernent with the finished work piece 50 preparatory to ejecting said work piece from the machine. Near the end of the movement of the piston 70 it closes a switch member 95 for completing an electrical circuit 96 through a solenoid 97, energization of which reversely shifts the valve 89 causing a reversal of flow of the hydraulic medium to the cylinder 69, actuating the piston 70 to the right as seen in Figure 13. During the movement of the piston 70 to the right and near the end of its stroke in this direction an electrical switch 98 is closed for completing the electrical circuit 99 through a solenoid 100.

The reverse movement of the piston 70 elevates the ejector arm which was previously engaged with the finished work piece, and as the ejector arm swings upwardly with the finished work piece thereon, an unfinished work piece is suitably released from a magazine and permitted to drop into the grinding throat on to the work rest blade. The shifting of the piston 70 to the left, Figure 13, also withdraws the pressure roller from the work piece so that said work piece may be ejected, and conversely when the piston is subsequently actuated to the right after the new work. piece has been mounted on the work rest blade, effects a return of the pressure roller into engagement with the work piece. The above mechanism is not, of itself, a part of the present invention and is fully described and shown in the above noted application Serial No. 374,556.

Completion of the electrical circuit 99 to effect the energization of the solenoid 100 procures shifting of a reversing valve 101 contained in a valve casing 102. This valve casing is connected tofthepump 24 by a branch pressure conduit 103 for conveying the hydraulic medium under pressure thereto, and is connected by a conduit 104 to one end of a cylinder 105 containing the piston 106. This piston 106 is connected by the piston rod 107 and a bracket, not shown, with the slide 44 for effecting a longitudinal movement of said slide relative to the bed 15. The medium in the cylinder 105 ahead of the piston 106 is expelled through branch conduit 108 to the valve casing 102 where it is directed by the valve 101 to a return conduit 109. As the slide 44 moves to the right to position the work piece in operative position relative to the grinding wheel, an adjustable dog 110 on said slide engages the lever 84 and, through the link 85 connected thereto, shifts the valve 101 to a neutral position, in which fluid is locked in both endsl of the cylinder 105,r thereby stopping the movement of said slide when the grinding wheel is in operative position relative to the work piece.

At the end of the movement of the slide 44 to the right, it engages and closes a switch 111 for completing an electrical circuit 112 through a solenoid 113, the latter operating to shift a reversing valve 116 contained within a casing 117. This casing 117 is connected by way of a conduit 118 with the pressure conduit 25 for conveying thereto the hydraulic medium under pressure. This hydraulic medium is connected through the valve 116, and branch conduit 119 with one end of a cylinder 120 containing a piston 121. The piston 121 expels the hydraulic medium ahead of it through a conduit 122 to the valve casing 117 where it is connected by conduit 123 with the exhaust conduit 94.

The piston 121 operates an arm 124, Fig. 6, for oscillating a shaft 125 journaled in the work head slide 44. Secured to the shaft 125 is a cam 126, Fig. 5, for oscillation with the shaft 125 and contacting with a roller 127 rotatably secured to an ear or lug 128 depending from a nut 129 threaded to a shaft 130. The shaft or screw 130 is carried by the cross-slide 47 for the work head so that any movement imparted to the nut 129 andV screw 130 will correspondingly shift the As was noted above, this shifting of the crossslide 47' effects a radial feeding movement between the work piece and grinding wheel, causing a continuous change in the size of the work piece. When the bore of the work piece is enlarged to the desired size, the diamond point 76 swings by the center of the work piece, thereby oscillating the cam member 79 and closing the switch 81. The closing of the switch 81 completes an electrical circuit 131 through a solenoid 132, and energization of the solenoid 132, upon closing of the switch 81, procures a reverse movement of the valve 116 and a retraction of the work and grinding wheel in a lateral direction by shifting the slide 47 rearwardly.

At the same time the closing of the switch 81 completes an electrical circuit 133 through a solenoid 134 for reversely shifting the valve 101 which controls the longitudinal movement of the work head, thus procuring a movement of the slide 44 with the work head thereon to the left. When the work head approaches its retracted limit of movement. it effects the closing of the switch 86, as above pointed out, to procure repetition of the cycle above described.

From the foregoing, it will be noted that a machine is here provided for automatically, expeditiously, grinding the internal bore of wgrk pieces to a predetermined size and form.

The wheel head slide 42 has formed on the rearward side thereof a T-shaped slot 135 whereby a dog 136 is adjustably secured to the slide 42. This dog 136 effects the stopping of the reciprocatory movement of the grinding wheel head at the left hand end of movement (Fig. 1') when it is desired to effect a re-truing or redressing of the operative face of the grinding wheel. This stopping of the wheel head is effected through an electrical switch 137 structurally illustrated in Figure 12 of the drawings. The switch itself to the rear face of the bed 15. It will be noted that the dog 136 is so formed and positioned as to engage the switch for closing same when the Wheel head is in its extreme left hand position, as seen in Fig. 1.

The work head slide 44 is also provided with a T-slot 138 in which the adjustable dogs 139 and 140 are mounted. The former of these dogs is adapted to engage a roller 141 carried by a plunger 142, Fig. 11, projecting upwardly from a housing or casing 143, and the dog 140 is adapted to engage the plunger 144 of a switch 145 secured to the rear face of the bed l5. By reference to Figure 2, it will be noted that the relationship of the dogs 139 and 140 is such that the dog 139 is about to pass olf of the roller 141 before the dog 140 engages the switch 145. The purpose of this construction will be described in detail later.

The mechanism operated by the plunger 142 is substantially a counting mechanism so that after a pre-determined number of pieces have been ground, the wheel is automatically trued. To this end, the plunger 142 is provided intermediate its ends with a notch 146, Fig. 11, in which is disposed an enlarged portion 147 of a lever 148. The lever 148 is secured to a shaft 149 rotatably journaled in the' housing 143. One end of the lever 148 is adapted to engage an adjustable stop 150 which determines the extent of projection of the roller` 141 beyond the housing 143. The other end of the lever contacts with a spring pressed plunger 151 whereby the plunger is held resiliently in elevated position.

The shaft 149 has secured thereto for oscillation therewith an arm 152, Fig. 10, to which is pivotally mounted a paWl 153 adapted to engage and interlock with ratchet teeth on a ratchet 154 loosely journaled on the shaft 149. The ratchet 154 has integral therewith a sleeve 155 (see Fig. 9) which passes through a bearing lug 156 integral with the casing or housing 143. A friction shoe 157 yieldably mounted in a suitable bore formed in the housing 143 or its cover plate 158 yieldably engages the sleeve 155 to prevent undesired reverse rotation thereof. Secured to either the sleeve or the ratchet and here shown as pinned to the ratchet is a cam plate 159 having lugs or projections 160, Fig. 10, extending from its periphery.l While there is but a single lug shown in the drawings, it is to be understood that additional lugs may be formed as desired. The lugs or lugs 160 are adapted to engage and depress a spring loaded plunger 161 for closing a switch 162 and completing an electrical circuit.

The switch 162, as shown diagrammatically in Figure 13, completes an electrical circuit 163 which includes a wire 164 extending from one contact of the switch 162 to one terminal of a solenoid 165 adapted to oscillate a lever 166, Fig. 10, pivoted at 167 within the housing 143. The lever 166, is connected with a comparatively long valve 168 which is contained within a casing 169 and directs the hydraulic medium from a branch pressure line 170, Fig. 13, to a conduit 171 which terminates in cylinder 172. The cylinder 172 contains a piston 173 from which projects a piston rod 174, and said cylinder is formed integral with, or may be secured to, a bracket 175, which is in turn mounted on the cross-slide 47 for the work head 47, as shown in Fig. 14. The piston rod 174 carries at its forward end a diamond or truing tool holder 176 for supporting the diamond or truing tool '177. The hydraulic medium ahead of the piston 173 is-cxpelled from the cylinder 172 through a conduit 178 to the valve casing 169 where it is connected with a conduit 179 which: directs the fluid to the sump or tank 22. The valve 168 also controls the huid exhausting from the cylinder 120 which controls the longitudinal movement of the Work head. As shown, the exhaust conduit from the cylinder 105 which actuates the work head is connected with a valve chamber 181 formed behind the piston cylinder 172 and said chamber is connected by a conduit 180 to said valve cylinder 169. Within the valve chamber 181 is a piston valve 182 which is integrally connected with and shifted by the piston 173. Extending from the valve chamber 181 is a conduit 183 which connects with the exhaust conduit 123 leading to conduit 94. This valve arrangement provides a safety feature to prevent advance of the work head into operative relation to the grinding wheel, if for any reason the truing tool is not retracted from its advanced operative position. With the truing tool in advance position, the flow of uid from the conduit 180 is prevented by the valve 182 which closes the port for said conduit into the chamber 181, and when the main control valve 168 is in the normal position shown in which position the work head is allowed to advance at the normal rapid rate, ow oi' fluid through the chamber 181 is not possible so that the work head is not allowed to move until the truing tool is fully retracted.

The valve 168 when shifted connects the exhaust from the cylinder 105 with a branch exhaust conduit 184 which is provided with a choke valve 185 of the needle type whereby the rate of movement of the work head and truing tool longitudinally of the machine is controlled and reduced during the actual truing operation. The branch conduit 184 connects with the exhaust conduit 179 which terminates in the tank or sump 22.

As shown structurally in Figure 10, the lever 166 has formed on its upper end a cam face 186 which is utilized for vertically shifting the plunger 187 upon shifting movement of said valve 168 to close a switch 188. The closing of this switch 188 connects the wires 189 and 190, the latter 'of which terminates in one contact 191 of the switch 137. The second contact 192 of this switch completes an electrical circuit which includes a solenoid 193 which is arranged for oscillating a lever 194, Fig. 8. The lever 194 is connected to the start and stop valve 34 for shifting said valve to cut oilthe flow of the hydraulic medium through the exhaust conduits 32 and 35 and stopping further reciprocation of the wheel head. From this it will be seen that after the plunger 142 has been depressed a predetermined number of times, the wheel head is stopped and the truing tool projected into the line of movement of the grinding wheel. Simultaneously the rate of speed of movement of the truing tool and work head are reduced to the desired speed for properly truing the active face of the grinding wheel. The work head continues in a direction to operatively associate the wheel and work at this reduced speed during the truing operation and as soon as the diamond has traversed the entire face of the grinding wheel, the second dog 140 on the Work head slide engages the plunger 144 of the electrical switch 145 for bridging the contacts 196 and 197 thereof. The contact 197 has extending therefrom a wire 198 which is connected to a solenoid 199 for reversely shifting the lever 166 and returning the valve 168 to the position indicated in Figure 13.

At the time the start and stop valve 34 was shifted by the lever 194 the latter,`which has formed on its upper surface the cam portions 200 and 201 Fig. 8, actuates a pair of switch plungers for opening the switch 202 and closing the switch 203, Fig. 7. The switch 202 is contained in the lead 190 which is in the circuit prevously completed by the closing of switch 188. When the valve 34 is shifted through the energization of solenoid 193, the switch 202 is opened to deenergize said solenoid to permit reverse shifting of the valve 34 when desired. The switch 203 is employed for completing the electrical circuit which energizes, as above described, the solenoid 199 as well as a solenoid 204, which latter reversely shifts the valve 34 to set the wheel head in motion. The energization of the solenoid 199 returns the valve 168 to original position for retraction of the dressing tool and restoration of the normal rate of travel of the work head.

It is now evident that there has been provided a grinding machine operating in a cyclic manner in which the grinding wheel is periodically trued without materially interfering' with the continuous production of the machine. Furthermore, it will be noted that no interference can be had between the diamond or truing mechanism and the rest of the parts due to a jam in certain of the mechanism after the said wheel has been trued, since a failure of the truing tool to be retracted upon shifting of the main valve 168 involves a stopping of the movement of the work head toward operative position. This stopping of the work head will attract the operators attention so that he may retract the truing tool.

In the operation of the machine, with the work table approaching the grinding wheel from the inoperative position of Fig. 1, the dog 110 shifts the reversing lever and brings said table to rest in operative position. yIn this position, the table closes a switch 111 to procure a cross-feed movement of the cross-slide for the grinding operation by energization of solenoid 113 which shifts the valve 116, thereby directing uid under pressure to the cylinder 120.

Grinding continues as a result of the crossfeed movement and with the grinding wheel reciprocating over the surface of the workpiece until the work piece reaches the finished size as determined by a gauge, which operates to close the switch 81. Closing of this switch energizes the solenoids 132 and 134 for a lateral and axial retraction of the work piece from the grinding wheel, the axial retraction involving movement of the slide 44 to the left. As the slide 44 ap,- proaches the* left hand end of movement, the dog 83 operates to close the switch 86, thereby energizing the solenoid 88 for ejection of the work piece from within the work supporting member. Movement of the ejector procures reversal of its own movement by closing the switch 95 and at the end of movement of the ejector, the latter operates to close the switch 98, thereby energizing the solenoid 100 for reversing the movement of the slide 44 to return the work head to operative position relative to the grinding wheel.

The work head, at each approach to the grinding Wheel, depresses, through/the dog 139, the plunger 142 which actuates the counting mechanism so that after a predetermined number of work pieces have been ground, the switch 162 is closed to procure shifting of the main control valve 168 which latter projects the truing tool into a position for engagement with the grinding wheel. Movement or the valve 168 also closes the switch 188 for partially completing a circuit through the electromagnet 193 which actuates the start and stop valve 34 for the wheel head. As said wheel head reaches the left hand end of its movement, Fig. 1, the circuit through the electromagnet 193 is closed by engagement of the dog 136 with the switch member 13'7, thereby completing the circut through the electromagnet 193 -to procure shifting of the valve 34 and thus to bring the wheel head to rest during the time that the truing tool is advancing past said wheel.

The shifting movement of the valve 168 in response to energization of the solenoid 165 also directs the exhaust from the cylinder which actuates the work head past the needle valve 185, thereby reducing the speed of the work head to carry the truing tool at a slow rate of speed past the grinding wheel.

The shifting of the valve 34 by the solenoid 193 also opens the switch 202 to deenergize the solenoid 193 to permit shifting of the valve 34 in the opposite direction at a later time, and also closes the switch 203 which is in series with the switch 145 actuated by the work head. Closing of both of said switches 145 and 203 provides for energization of the solenoid 204 which is in the circuit controlled by those switches. As the work head continues to advance toward the grinding wheel and after the truing tool has been carried past said grinding wheel, the switch 145 is closed by the dog 140 on the work head, thereby energizing the solenoid 204 to return the valve 34 to original position to permit further reciprocation of the wheel head. Closing of switch 145 also returns the control valve 168 to original position by energization of the solenoid 199 which is in` series with the solenoid 204. The return movement of said valve 168 procures retraction of the dressing tool and also permits the work head to be advanced at the normal rate of speed toward the grinding wheel. The grinding operation then continues, as above described, until the counting mechanism under the control of the dog 139 again closes the switch 162 to procure another dressing operation.

In the event that the dressing tool is not properly retracted, the work head is brought to rest since the exhaust of fluid from the work advancing cylinder, which is now directed through the valve chamber 181 by the control valve 168, is blocked by the valve 182 connected to the dressing tool actuated piston. When the dressing tool is retracted properly, the fluid exhausting from the cylinder 105 which controls the work head, passes through the valve chamber 181 without restriction.

What is claimed is:

1. An internal grinding machine including a bed, a grinding wheel rotatably mounted thereon for reciprocation relative thereto, means for effecting a continuous reciprocation of said grinding wheel, a work support mechanism mounted on the bed for movement in a direction axially of the wheel to present a work piece in operative relation to the zone of reciprocations of the wheel or to retract the work piece with respect to the wheel, means to effect rapid retracting movement of the work support with respect to the wheel, means for slowly advancing the work in the direction of the wheel, a truing device carrled by and movable with the work support, means for projecting the truing device into a position to engage the wheel during movement of the work support in the direction to present a work piece to the grinding wheel, and means for automatically discontinuing reciprocation of the grinding Wheel prior to engagement of the truing tool therewith.

2. An internal grinding machine including a bed, a grinding wheel rotatably mounted thereon for reciprocation relative thereto, means for eifecting a continuous reciprocation of said grinding wheel, a work support mechanism mounted on the bed for movement in a .direction axially of thewheel to present a work piece in operative relation to the zone of reciprocations ofthe Wheel or to retract the work piece with respect to the wheel, means to eifect rapid retracting movement of the work support with respect to the wheel, means for slowly advancing the work in the direction of the wheel, a truing device carried by and movable with the work support, means for projecting the truing device into a position to engage the wheel during movement of the work support in the direction to present a work piece to the grinding wheel, and means for automatically discontinuing reciprocation of the grinding wheel and maintaining same in proximate relation to the work support prior to the engagement of the truing device therewith.

3. An internal grinding machine including a bed, a grinding wheel rotatably mounted thereon for reciprocation relative thereto, means for effecting a continuous reciprocation of said grinding wheel, a work support mechanism mounted on the bed for movement in a direction axially of the wheel to present a work piece in operative relation to the zone of reciprocations of the Wheel or to retract the work piece with respect to the wheel, means to effect rapd retracting movement of the work support with respect to the wheel, means for slowly advancing the work in the direction of the wheel, a truing device carried by and movable with the work support, means for projecting the truing device into a position to engage the wheel during movement of the work support in the direction to present a work piece to the grinding wheel, means for automatically discontinuing reciprocation of the grinding wheel prior to engagement of the truing tool therewith, and means for automatically moving the truing device out of the path of reciprocations of the grinding wheel after traverse of the truing tool thereover.

4. An internal grinding machine including a bed, a grinding wheel rotatably mounted thereon for reciprocation relative thereto, means for eifecting a continuous reciprocation of said grinding wheel, a work support mechanism mounted n the bed for movement in a direction axially of the wheel to present a work piece in operative relation to the zone of reciprocations of the Wheel or to retract the work piece with respect to the wheel, means to effect rapid retracting movement of the work support with respect to the wheel, means for slowly advancing the work in the direction of the Wheel, a truing device carried by and movable with the work support, means for projecting the gage the wheel during movement of the work support :In the direction to present a Work piece to the grinding wheel, means for automatically discontinuing reciprocation of the grinding Wheel prior to engagement of the truing tool therewith, means for automatically moving the truing device out of the path of reciprocations of the grinding wheel after traverse of the truing tool thereover,

truing device into a position to enand means for initiating reciprocating stroke of the grinding wheel in a retracted direction as respects the direction of advance of the work support.

5. An internal grinding machine including a bed, a grinding wheel rotatably mounted thereon for reciprocation relative thereto, means for effecting a continuous reciprocation of said grinding wheel, a work support mechanism mounted on the bed for movement in a direction axially of the wheel to present a work piece in operative relation to the zone of reciprocations of the wheel or to retract the work piece with respect to the wheel, means to effect rapid retracting movement of the work support with respect to the wheel, means for slowly advancing the work in the direction of the wheel, a truing device carried by and movable with the work support, means for projecting the truing device into a position to engage the wheel during movement of the work support in the direction to present a work piece to the grinding wheel, means for automatically discontinuing reciprocation of the grinding wheel prior to engagement of the truing tool therewith, means for automatically moving the truing device out of the path of reciprocations of the grinding wheel after traverse of the truing tool thereover, means for initiating reciprocating stroke of the grinding wheel in a retracted direction as respects the direction of advance of the work support, and means for automatically effecting a relative radial feeding movement of work support and grinding wheel subsequent to completion of the truing operation.

6. A grinding machine of the nature described including a bed, a grinding wheel spindle rotatably mounted on the bed, means for effecting rotation of the grinding wheel, means for eifecting an interruptable rcontinuous reciprocation thereof in pre-determined zone of movement, a work support mounted on the bed and movable axially in a direction toward and from the grinding wheel to present a work piece in overlying opposed relation to the grinding wheel or to retract the work piece with respect thereto, means for effecting a relatively slow movement of the work support in the direction of approach i to the grinding wheel, a truing device, means for temporarily projecting the truing device into a position to engage the operative surface of the grinding wheel prior to movement of the work and grinding wheel into their opposed relation, means for retracting the truing device from the plane of the operative surface ofthe grinding wheel prior to grinding engagement between a work piece on the work support and said grinding Wheel, means for feeding the work support and grinding wheel in a direction one toward the other to eifect stock removal from a work piece carried by the Work support, means for automatically Adetermining the extent oi said feeding movement, means for rapidly retracting the work support in an axial direction as respects the grinding wheel at the termination o1 the prescribed feeding movement, and means effective during reciprocated movement of the work support for checking reciprocation of the grinding wheel at the proximate portion of its stroke in the direction of the work support. l

7. In a grinding machine of the class described the combination of a bed, a grinding wheel rotatably mounted thereon for reciprocation relative thereto, a work head shiftable from a point remote from the grinding wheel to a point in If operative association therewith, a truing tool carried by the work head, means for shifting the Work head at normal rapid speed and slow truing speed, means for projecting the truing tool into the path of reciprocation of the grinding wheel, means for stopping the reciprocatory movement of the wheel and changing the rate of movement of the work head during the truing operation, and means for insuring the retraction of the truing tool after the truing operation before movement of the work head at its rapid rate is resumed.

8. In a grinding machine of the class described the combination of a bed, a grinding wheel rotatably mounted thereon for reciprocation relative thereto, a work head shiftable from a point remote from the grinding Wheel to a point in operative association therewith, a truing tool carried by the work head, means for shifting the work head at normal rapid speed and slow truing speed, means for projecting the truing tool into the path of reciprocation of the grinding wheel, means for stopping the reciprocatory movement of the wheel and changing the rate of movement of the work head during the truing operation, and means for holding the work head against movement after the truing operation is complete prior to the retraction of the tool from the path of movement of the grinding wheel.

9. In a grinding machine of the class described the combination of a bed, a grinding wheel rotatably mounted thereon, means for reciprocating the wheel through a given zone, a work head mounted on the bed and shiftable from a work loading position remote from the grinding wheel to a position in operative association therewith, means for actuating the grinding wheel and work head relative to one another to operatively associate same, means for shifting said parts relative to one another at a slow truing rate of speed, means for simultaneousl5T stopping the movement of oneof the parts and projecting the truing tool into the plane of reciprocation of the active face of the grinding wheel, and means holding the parts against movement until the retraction of the truing tool from the plane of the surface of the grinding wheel.

10. In a grinding machine of the class described the combination of a bed, a pair of slides mounted thereon and shiftable relative thereto toward and from one another, a rotatable grinding Wheel mounted on one of the slides, a truing tool mounted on the other slide and having a position of the plane of movement of the active face of the grinding wheel and a position remote therefrom, means for shifting one ofthe slides at a rapid rate to operatively associate the truing tool and grinding wheel, means for slowly shifting said slide during the truing operation, means for projecting the truing tool from its remote position to a position in the planeof movement of the wheel, and means for holding the slides against normal movement after the truing operation and until the truing tool is retracted to its remote position.

1l. In a grinding machine of the class described the combination of a bed, a pair of slides mounted thereon and movable relative thereto 103 toward and from one another, a rotatable grinding Wheel on one of the slides, a truing tool mounted on the other slide, means for projecting the truing tool from a position remote from the plane of movement of the grinding wheel to a 195 point in said plane of movement, hydraulic mean: for shifting the slides at a rapid rate to operatively associate the tool and wheel, hy draulic means for shifting the slides at a slow rate during the truing operation, a valve con- 11b trolling the hydraulic means and stopping one of the slides during the truing operation, and additional hydraulic control means for holding the slides against movement after the truing operation until after 'the retraction of the truing tool.

FREDERICK V. GEIER. FREDERICK S. HAAS.

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