US2769280A - Grinding apparatus, particularly for grinding billets and the like - Google Patents

Description

Nov. 6, 1956 G. E. coMsTocK, 30 2,769,280 GRINDING APPARATUS. PARTICULARLY FOR GRINDING BILLETS AND THE LIKE Filed July 22, 1955 5 Sheets-Sheet l mlTH INVENTOR.

GEQREE E; EUM5TUEK,3R D.

4&4. T/MM ATTURNEY Nov. 6, 1956 G. E. coMsTocK, 3D

GRINDING APPA 2,769,280 RATUS. PARTICULARLY FOR BILLE'I'S AND THE LIKE GRINDING 5 Sheets-Sheet 2 Filed July 22, 1953 INVENTOR. GEIJRGE E; CUM-STUCK, 3R1].

ATTU RNEY Nov. 6, 1956 G. E. COMSTOCK, 30 2,769,280 GRINDING APPARATUS. PARTICULARLY FOR GRINDING BILLE'I'S AND THE LIKE Filed July 22, 1955 5 Sheets-Sheet 3 I I5 7 I59 242 I INVENTOR. GEURGE E. EUM5TUEK,3RD.

} WMU ATTORNEY Nov. 6, 1956 GRINDING 'APP'A E COMSTOCK, 3D

RATUS, PARTICULARLY FOR GRINDING BILLETS AND THE LIKE Filed July 22, 1953 5 Sheets-Sheet 4 IN V EN TOR.

Nov. 6, 1956 G. E. COMSTOCK, so GRINDING APPARATUS. PARTICULARLY FOR GRINDING BILLETS AND THE LIKE 5 Sheets-Sheet 5 Ten/vs Fa ,eMae

Filed July 22, 1953 INVENTOR. 550555 E Cums "raaK, B' d.

United States Patent GRINDING APPARATUS, PARTICULARLY FUR GRINDING BILLETS AND THE LIKE George E. Comstock, 3d, Holden, Mass, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts This invention relates to grinding machines. More particularly, this invention is in improvements in snagging grinders for surfacing steel billets and the like.

Many various and often some heavy manual burdens may be involved in operating snagging grinders according to past practices; on the other hand, various dlifiCLllllGS are encountered and sometimes other or different physical or mental burdens have to be assumed by the operator when the effort is made to devise means to simplify and ease his labors. One of the objects of this invention is to provide a snagging grinder apparatus the operation and control of which by the operator will be dependably simple and will materially and reliably ease or relieve his manual burdens. Another object is to provide a snagging grinder for effecting dependable and widely flexible relative movements between the billet and grinding wheel under manual controls that are easy and simple to operate and are constructed and arranged to provide ease and facility of access. Another object is to provide a snagging grinder in which may be dependably achieved the advantages of substantial elimination of physical exertion on the part of the operator and yet avoid or greatly lessen risk of nervous fatigue in providing for minimum operator attention in certain areas of the snagging operation and thus afford maximum opportunity to control and supervise the grinding action itself. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements 0 parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

in the accompanying drawings in which is shown illustrated one of the various possible embodiments of the mechanical features of this invention and in which similar reference characters refer to similar parts throughout the several views,

Fig. 1 is a side elevation of the snagging grinder, the front being at the left;

Fig. 2 is a horizontal sectional view, taken approximately on the line 2-2 of Fig. 1, showing the snagging grinder in elevation, the front being again at the left;

Pig. 3 is a vertical sectional view, on an enlarged scale, as seen from the front or the left along the line 33 of Fig. 1;

Fig. 4 is a fragmentary sectional view, on an enlarged scale, on the line 44 of Fig. 1, showing a yieldable con nection;

Fig. 5 is a fragmentary horizontal sectional view, on an enlarged scale, as seen along the line 55 of Fig. 1, showing a grinding wheel mounting and drive pulleys;

Fig. 6 is a vertical sectional view, on an enlarged scale, as seen along the line 66 of Fig. 7, through one of the control valves;

Fig. 7 is a hydraulic diagram of the actuating mechanisms and the controls of the machine, showing also certain electrical controls;

Fig. 8 is a simplified diagram of electrical circuit con- Patented Nov.

nections and co-acting electrical controls, certain portions thereof being as a whole indicated schematically; and

Fig. 9 is an illustrative amplifier and relay circuit arrangement showing diagrammatically details of portions shown schematically in Fig. 8, and

Fig. 10 is a vertical sectional view, on an enlarged scale, as seen along the line 1tl1(l of Figure 7, through one of the control valves, showing a preferred form thereof.

As is known, steel billets vary in dimensions and may even vary, throughout any face or surface to be ground, in hardness or resistance to stock removal. To avoid having the operator manually traverse or move the grinding Wheel relative to the billet surface as well as to apply manually the force which determines pressure of grinding contacts, provision is made for utilizing power-actuated mechanisms for effecting these relative movements, pressureapplications, and the like, and a suitable and illustrative apparatus for these purposes is about to be described in an illustrative form in order better to understand certain features of my invention. lllustratively, for effecting relative traverse movement between the work-piece or billet and the grinding wheel, the apparatus traverses or moves the grinding wheel and preferably also the operators station (and hence also the operator) relative to the billet but this arrangement, unless otherwise indicated in the claims, is to be understood as illustrative and not in a limiting sense. Preferably the apparatus, with the operatcrs station, is movably supported by overhead runways, such as ceiling-supported guide rails, thus lessening handling of the billets, which are heavy.

The snagging grinder comprises a pair of parallel overhead l-beams 10 and 11 (Figs. 1 and 2) which serve as a runway or railed support for a movable carriage 12. The carriage 12 is provided with a plurality of pairs of rollers 13, 14, 15 and 16 (Fig. 2) which ride upon the upper surfaces of the outside flanges of the I-beams 1G and 11 and co-act to form a running roller support for ease and guidance of movement of the carriage 12.

A traversing drive mechanism is provided for moving the carriage 12 longitudinally of the I-beams comprising a shaft 17 rotatably supported on the carriage 12. The shaft 17 is provided at its ends with driving wheels 18 and 19 (Fig. 2) which ride upon and drivingly engage the upper surfaces of the inside flanges of the I-beams 10 and 11. A second drive shaft 20 is rotatably supported on the carriage 12 spaced from the shaft 17. The drive shaft 20 is provided at its ends with driving wheels 21 and 22 which similarly ride on and engage surfaces on the inside flanges of the I-beams 10 and 11. In this manner, the weight of the carriage and the load it carries aid in providing driving traction.

A fluid motor 23 supported on the carriage 12 is connected by a link chain 24 with a rotatable shaft 25. The shaft 25 is connected by a link chain 26 with the shaft 17. The shaft 17 is provided with a sprocket 27 which is connected by a link chain 28 with a sprocket 29 on the shaft 20. Rotary motion of the fluid motor 23 may thus be imparted through the link chain driving mechanism syn chronously to rotate the shafts 17 and 20 thereby rotating the driving wheels 1S19 and 21-22 to traverse the carriage 12 longitudinally along the I-beams it and 11.

I provide a suitable means for translating the travel of the carriage 12 along the I-beam rails 3.9 and 11, both directionally and quantitatively, into an electrical quantity, for purposes later described, and this means may take the form of a variable or potentiometer resistance unit actuated according to the direction and extent of carriage movement; it is indicated in the drawings (Figs. 1 and 2), as a whole, by the designation HP, be ing secured to the carriage in any suitable way so that the pinion 43 of its rotary resistance-varying shaft meshes with a rack 44 fixed to I-beam rail 11 and is turned in direction and extent according as the carriage drive effects carriage movement along the rails 10, 11. Its rotary shaft shifts a slide contact along an internal resistance wire helix. In detail and in its co-actions, it is later described.

The carriage 12 may be built up, comprising a pair of plates 39 and 31 (Fig. 2), the end portions of which clamped around a pair of spaced parallel transversely extending tubular frame members 35 and 36. The plate 30 serves as a support for motor drive of the traversing mechanism previously described and also for support ing the outside wheels 13 and 14 and one end of the drive shafts 17 and 20. Similarly the plate 31 serves as a support for the outside wheels 15 and 16 and also for the other ends of the drive shafts 17 and 20. The end portions of plates and 31 surround a portion of the tubular rods 35 and 36 and are provided with clamping plates for securing to the rods 35 and 36 thus forming the main frame of the carriage 12.

A vertical cross plate 37 is provided with spaced enlarged end split sleeve-like portions 38 and 39 (at the left, in Figs. 1 and 2) which surround the tubular rods 35 and 36 respectively at the ends thereof to one side of the I-beam rails, and are clamped thereto. The plate 37 also braces the frame parts 35 and 36 and serves as a rigid support for a pair of spaced parallel vertically arranged tubular frame members 40 and 41, the lower ends of which support an operators control platform 42 that is in line with the grinding wheel later described so that its operation can be easily watched by the operator and controlled from the platform carrying the operator, which, travels longitudinally of the overhead rails and with the carriage 12 as the latter moves relative to the billet. The control platform 42 is provided with easily set manual and automatic controls hereinafter described whereby operating mechanisms of the machine may be readily controlled; the operator, carried on platform 42, simply rides along with the carriage 12 as the latter moves lengthwise of the billet. The shape, dimensions and positioning of the billet may widely vary in practice. The shape, dimensions and positioning of the billet may widely vary in practice.

The horizontal tubular frame rod 36 serves as a pivotal support for a plate 45 (Figs. 2 and 3). The righthand end of the plate 45 (Fig. 3) has an enlarged portion 46 surrounding the tubular rod 36. The plate 45 is provided with two spaced depending bosses 47 and 48 having bearings (not shown) for supporting a rock shaft 49. The rock shaft 49 has secured thereto intermediate of bearing bosses 47, 48 and thus pivotally supports a vertically arranged depending hollow column 50. The column 50 is provided with an enlarged upper portion 51 which is fixedly supported on and pinned to the rock shaft 49. The lower end of the column 50 has fixedly secured a bracket 52 (Fig. 3) which supports a rock shaft 53 in spaced bearings as shown in Figure 3. The rock shaft 53 in turn supports a bracket 54 (Figs. 1 and 3) having an enlarged lower portion 55 which surrounds and forms an elongated bearing (Fig. 1) for a round or cylindrical portion of the frame 56a of a swing frame grinder generally indicated as a whole at 56. The swing frame grinder 56 may be any one of several well known commercial units having a wheel spindle 57 mounted at one end of frame 56:: thereof, the wheel spindle 57 being arranged to support and rotate a grinding wheel 58, which is partially surrounded by a wheel housing or guard 59. The other end of frame 56a of the swing frame grinder is provided with a rock shaft 66 (Fig. 1) which pivotally supports a motor platen 61 having an electric motor 62 fixedly mounted thereon. The motor 62 is provided with a multiple V- groove pulley 63 which is connected by V- belts 64 and 65 to drive the grinding wheel, as by way of V-grooves formed in the periphery of a pair of wheel flanges 66 and 67 between which is clamped the grinding wheel 58 (Fig. 5). Any suitable mechanism may be provided to set the tilt of the motor platen 61 about the axis of shaft so as to tension the V-belts 64 and as desired. Such mechanism may comprise a manuallyrotatable screw threaded through an articulatedly-connected nut carried by the motor platen 61 and having its end rotatably anchored or held in any known or suitable manner in the frame 56a of the swing-frame grinder, substantially as indicated in Figure 1 and as will be well understood by those skilled in the art.

A work-piece such as a billet 70 to be ground is positioned crosswise of and underneath the structure, resting on a work support 71 (Figs. 1 and 2) and when column 50 pivots or swings about the axis of the rock shaft 49, it achieves a reversible cross shift of the swing frame grinder 56 (left to right and reverse, as seen in Figs. 1 and 2) which is at the lower end of column 50, shifting grinding wheel 58 crosswise of work 70. The swing frame grinder 56, reversibly pivoting about the axis of the rock shaft 53 which is at parallel to axis of shaft 49, oscillates the grinding wheel 53 and co-acts to hold it in operative engagement with the work-piece 70 being ground. The billet 70 (Figs. 1 and 2) extends parallel to the line of overhead i-beam rails 10, 11, so that, as carriage 12 moves therealong, the grinding wheel 58 is moved lengthwise of the billet, along with the operator on platform 42.

Power means, illustratively hydraulically operated, are provided for tilting the swing frame grinder 56 about its longitudinal axis, to pivot the swing frame grinder about the axis of the rock shaft 49, and to rock the plate 45 about the axis of the tubular rod 36. One of these power means is a hydraulic motor in the form of cylinder 75 (Figs. 1, 3 and 7) having a slidably mounted piston 76 connected to one end of a piston rod 77. The cylinder 75 is pivotally supported by a stud 78 in a rigid bracket 79 depending from the plate 45. The right hand ends of the piston rod 77 (Fig. 1) is pivotally connected by a stud 8i] (Figs. 1 and 3) with an arm 81 which is fixedly secured to on the rock shaft 49. When fluid under pressure is passed through a pipe 82 into cylinder chamber 83, the piston 76 moves toward the right (Fig. 7) to impart a counter-clockwise (Fig. 1) swinging movement to the vertical column 50 and the parts supported thereby, moving grinding wheel 58 toward the right. During this movement fluid within the opposite cylinder chamber 84- is exhausted through a pipe (Fig. 7). When the flow of fluid is reversed and fluid under pressure passes through the pipe 85 into the cylinder chamber 84, clockwise swinging movement is imparted into the column 50 and grinding wheel 58 moves to the left in fig. 1. This mechanism, as later described, is made to function to effect cross-feed of the grinding wheel 58 in relation to its traversing strokes of reversible travel as effected by the movement of the carriage 12.

Another hydraulic motor has a cylinder 96 (Figs. 1 and 3) containing a slidably mounted piston 91 which is connected to a piston rod 92. The cylinder 93* is pivotally supported by a stud 93 on a bracket 94 which is fixedly secured on the column 59. The free end of the piston rod 92 (see Fig. 4) is provided with a transversely extending stud 89 which is connected by a pair of spaced tension springs 94 and 95 with opposed studs 96 carried by a sleeve 97 slidably mounted on the piston rod 92. The piston rod 92, by studs 96, is pivotally connected to the ends of spaced diverging arms 93 and 99. (Fig. 3) the lower divergent ends of which are fixedly secured to the rock shaft 53 which pivotally carries the column 50. When fluid under pressure is passed through a pipe 1% into a chamber 101. of cylinder 90, the piston 91 moves downward toward the left (Figs. 1 and 7) and piston rod 91 swings arms 98 and 99 in a counter-clockwise direction (Fig. 1) about the axis of the rock shaft 53 to impart a counter-clockwise swinging movement to bracket 54 and to the swing frame grinder 56 carried by it, depressing grinding wheel 58. During this movement fluid within opposite cylinder chamber 102 (Fig. 7) exhausts through a pipe 103. If the fluid under pressure is reversed so that it flows into cylinder chamber 102, through the pipe 103, a clockwise swinging movement is imparted to the swing frame grinder 56 about the axis of the rock shaft 53, raising the grinding wheel 58 (Fig. 1). On wheel-depressing movement, piston rod 92 acts through the tension springs 94 and 95 (Fig. 4) which serve to provide a yielding connection so that the grinding wheel 58 may be yieldingly maintained in operative engagement with the work-piece 70 being ground. On wheel-raising movement, the piston rod sleeve 97a (Fig. 4) can transmit lifting force directly from piston rod across stud 89 to the sleeve 97 with which the lever arms 98, 99 are directly connected by studs 96.

I provide another hydraulic motor preferably in the form of a cylinder 105 (Fig. 7) containing a slidably mounted piston 106 to which is connected one end of a piston rod 107. The cylinder 105 is pivotally connected by a stud 108 (Fig. 3) carried by the bracket 54 which supports the swing frame grinder unit 56. The free end of piston rod 107 is connected by a stud 109 with an arm 110 which is fixedly secured to the frame 56a of the swing frame grinder unit 56. When fluid under pressure is passed through a pipe 111 into cylinder chamber 112, the piston 106 and rod 107 move downward toward the left (Figs. 3 and 7) to swing the arm 11b and swing frame 56a in a clockwise direction. During this movement fluid within opposite cylinder chamher 113 exhausts through a pipe 114. If the fluid under pressure is reversed and fluid under pres-sure passes through the pipe 114 into cylinder chamber 113, the arm 110 together with the swing frame grinder unit 56 is rocked in counter-clockwise direction about the longitudinal axis of the swing frame grinder unit 56. This mechanism serves to facilitate tilting the grinding wheel so that grinding may be done by either one corner portion or the other of the grinding wheel 58.

Another hydraulic motor has a cylinder 115 which (Figs. 7 and 3) contains a slidably mounted piston 116 to which is connected one end of a piston rod 117. The cylinder 115 is pivotally supported at one end by a stud 118 carried by a bracket 119 which is fixedly secured on the tubular rod 35 and the carriage 12. The lower or free end of the piston rod 117 is pivotedly connected by a stud 120 with a yoked member 121 (Figs. 3 and 7) which has a bearing hole through which passes the rock shaft 49, forming a universal connection. When fluid under pressure is passed through a pipe 122 into cylinder chamber 123, the piston 116 moves downwardly (Figs. 1 and 7) to cause a downward movement of the piston rod 117 so as to swing the plate 45 and depending column 50 in counter-clockwise direction (Fig. 3) about the axis of the tubular rod 36. This gives the grinding wheel a sweeping-like movement relative to the surface being ground. During this movement fluid within opposite cylinder chamber 124 exhausts through a pipe 125'. If the fluid under pressure is reversed and passes through the pipe 125 into cylinder chamber 124, the piston 116 moves upwardly to cause an upward movement of the piston rod 117 thereby swinging the plate 45 together with column 50 and the swing frame grinder 56 in a clockwise direction, giving wheel 58 a sweep-like movement in reverse direction. This mechanism and motor-drive serves to impart longitudinal reciprocatory strokes to the grinding wheel 58 relative to the work-piece 70 being ground, during its longitudinal traverse movement as carriage 12 moves along its I-beam rails 10, 11. A fluid pressure system is provided for supplying fluid under pressure, such as oil, to the various hydraulic motors that actuate the mechanisms of the machine. A reservoir 130 is provided, conveniently within the vertically arranged pendant column 50. A fluid pump 131 (Fig. 7) driven by an electric motor 132 is mounted on the underside of a plate 133 (Figs. 1 and 2) which is fastened to the right hand ends of the tubular frame or carriage rods 35 and 36 (Figs. 1 and 2). The pump 131 draws fluid from the reservoir through a pipe 134 and forces fluid under pressure through a pipe 135 to the various mechanisms of the machine. An adjustable pressure relief valve 129 is connected to the pipe line 135 to facilitate returning excess fluid under pressure to the reservoir 130.

According to my invention, I am enabled, by certain controls later described in detail, very substantially to relieve the operator of the burden of correlating the various above-described motions and movements of parts and thus permit him, in etfect, to supervise the entire operation; this he may do by manipulating certain of these just-mentioned controls, and desirably also he can initially set manual which are present and which might first be described, and thus aid in understanding other features. The pressure pipe 135 conveys fluid under pressure through a branch pipe 136 to a plurality of manually operated control valves 137, 138, 139 and 140 by which may be controlled, directly, the passage of the fluid under pressure to and the exhaust of fluid from the fluid motor 23, the cylinder 75, the cylinder 90 and the cylinder 105, respectively, but, according to certain features of my invention, 1 provide other controls, later described, with which the manual control valves can coact; the latter are manually actuated, as by operating handles 141, 142, 143 and 144 respectively and may be identical in construction and hence only one of these valves need be illustrated in detail as in Fig. 6. Such illustrative construction will be hereinafter described.

Hydraulic motor 115116 is preferably automatically reciprocating under control of the part which it oscillates. Fluid under pressure from the supply pipe 135 (Fig. 7) also passes to a solenoid actuated control valve 145 for controlling the admission to and exhaust of fluid from the cylinder 115 so as to obtain when desired continuously oscillating or reciprocating sweep-like strokes of movement of the grinding wheel 55 during its traverse movement, as above mentioned. The solenoid valve 145 is a piston type valve having a slidably mounted valve member 146 provided with a plurality of valve pistons 147, 148, 149 and 150 formed integrally therewith. The valve member 146 is normally held in central position by a pair of balanced compression springs 151 and 152 at opposite ends thereof. A pair of solenoids S8 and 8-9 are provided at its opposite ends to shift the valve member 146 in either direction. With the valve positioned as in Fig. 7 oil under pressure from the sup ly pipe 135 into a valve chamber 155 formed between the valve pistons 148 and 149 respectively. When the solenoid S8 is energized, the valve member 146 moves toward the right so that fluid under pressure from the pipe 135 via pipe 126 passes through a valve chamber 155 formed between the valve pistons 148 and 149 and passes out through the pipe 122 into the cylinder chamber 123 to cause a downward movement of the piston 116 so as to rock the plate 45 in a counter-clockwise direction (Fig. 3), thereby imparting a stroke of movement of the grinding wheel 58 to the left in Figure 3. This occurs during stand-still of carriage 12; and wheel 58 thus moves lengthwise of billet 70. During this stroke of movement fluid within the cylinder chamber 124 eX- hausts through the pipe 125 into a valve chamber 156 formed between them and passes out through a pipe 157, through an adjustable needle valve Or throttle valve 158 and through exhaust or return pipe 159 into the reservoir 130.

When the solenoid 8-9 is energized, the valve member 146 moves towards the left (Fig. 7) so that oil from the supply pipe 135 entering the valve chamber 155 may pass through the pipe 125 into the cylinder chamber 124 to cause an upward movement of the piston 116, thereby rocking the plate 45 in reverse (clockwise) direction and thereby reversing the sweep-stroke of grinding wheel 58. During this stroke of movement, fluid from the cylinder chamber 123 exhausts through the pipe 122 into a valve chamber 168 formed between the valve pistons 149 and 150 and passes through a central passage 161 within the valve member 146 into the valve chamber 156 and out through the pipe 157, through the throttle valve 158 and the exhaust pipe 159 back to the reservoir 138. The throttle valve 158 controls the rate of exhaust of fluid from either end of the cylinder 115 and thereby controls the rate of movement of the piston 116; by setting valve 158, the rate of oscillation or reciprocation of the grinding wheel 58 may be suited to the grinding job at hand.

The plate 4-5 which is oscillated by the motor 115116 is provided with an actuating arm 165 (Figs. 3 and 7) which is arranged to engage either the actuating roller 166 of the limit switch LS1 or the actuating roller 167 of the limit switch LS2.

An electric circuit is provided to supply electric current. A manually operable starter switch 171) and a stop switch 171 are provided to stop and start the just described lateral oscillation or reciprocating movement of the grinding wheel 58. The limit switch LS1 is normally closed limit switch and the limit switch LS2 is normally opened. The limit switches LS1 and LS2 are connected through a relay switch 168 with the solenoids S-9 and 8-8 of the control valve 145. When the start switch 178 is closed current passes through the contactor 172 of the relay switch 168 to energize the solenoid S-8 so as to shift the valve member 146 toward the right so that fluid under pressure passes into the cylinder chamber 123 to cause a counter-clockwise (Fig. 3) swinging movement of the plate 45 and movement of the grinding wheel 58 to the right. This stroke of movement of the grinding wheel 58 continues until the arm 165 on carrier plate 45 engages the actuating roller 167 of the limit switch LS2 which closes a circuit thereby energizing the relay switch 168 to open the contactor 172 and to close the contactor 173. Opening the contactor 172 serves to deenergize the solenoid 8-8 allowing the valve member 146 to return to a central position. Closing the contactors 173 serves to allow current to pass through the relay switch 168 so as to energize the solenoid S9 thereby shifting the valve member 146 toward the left so as to admit oil to the cylinder chamber 124 to start a swinging stroke of movement of the plate 45 clockwise and movement of the grinding wheel 58 to the left. Thus a continuous oscillation or reciprocation of the grinding wheel is obtained.

When it is desired to stop the oscillation of the grinding wheel, the stop switch 171 is opened manually to render the circuit inoperative, thereby stopping the oscillation of the plate 45 and the grinding wheel 58.

A start switch 175 and a stop switch 176 are provided for stopping and starting the motor 132 for driving the fluid pump 131. A start switch 177 and a stop switch 178 are provided for controlling the stopping and starting of the wheel driving motor 62.

The manual control valves 137, 138, 139 and 140, as above noted, are preferably identical in construction. These valves are arranged side by side and fastened together by a plurality of tie rods 186, 181, 182 and 183 (Fig. 6). The valve assembly is fixedly mounted on a vertical plate 184 (Fig. 2) and supported at convenient height at the operators station 42.

Oil supply pipe 136 (Fig. 7) passes oil into a longitudinal passage 185 (Fig. 6) which extends through all four assembled valves. Similarly an exhaust passage 186 extends through all or" the valves 137, 138, 139 and 140 and is connected to an exhaust pipe 187 (Fig. 7) which connects to return pipe 159 to return exhaust fluid to the reservoir 138.

These valves are piston type valves each comprising valve stems 190 (Fig. 6) having valve pistons 191, 192 and 193 formed integrally therewith. A compression spring 194 is provided, normally to hold the valve in a central or neutral position as indicated in Fig. 6. The section of Figure 6 is through valve and shows hand lever 144; like the others, lever 144 is pivotally supported by a stud 195 on a link 196 which is in turn pivotally supported by a stud 197 formed in an upwardly extending lug 198 on the valve 140. Lever 144 is connected by a stud 199 with the upper end of the valve stem 198.

When the hand lever 144 is moved toward the operator on the platform 42 (Figs. 1 and 2), that is, toward the right in Fig. 6, valve stem 190 is depressed so that oil from the passage enters a valve chamber 208 formed between the valve pistons 192 and 193 and passes out through a passage 281, and through a pipe to the motor cylinder, in the case of valve 140, it passes by the pipe 111 into the cylinder chamber 112 of cylinder 105 to cause a downward movement of the piston 1156 thereby to tilt swing frame grinder unit 56 in one direction about its longitudinal axis; exhaust oil from the other cylinder chamber is returned to reservoir 130; and in the ease of cylinder chamber 113 is exhausted through the pipe 114 into a valve chamber 202 formed by the valve pistons 191 and 192 and through a passage 283 and into the longitudinal passage 186 and then by exhaust pipe 187 and return pipe 159 enters the reservoir 130.

Similarly as the hand lever 144 is moved away from the operator, that is, toward the left (Fig. 6) an upward movement is imparted to the valve stem 198 so that oil entering the valve chamber 2% passes through the pipe 114 to tilt the swing frame grinder unit 56 in opposite direction about its longitudinal axis. This valve as above stated serves to position the grinding wheel 58 for grinding by either one or the other of its corners. The valve stem is maintained in an upper or lower position only so long as the operator holds it in either of these positions by means of the manually operable handle 144. Upon release of the handle 144, the released compression of the spring 194 returns the valve stem 198 into the central or neutral position as indicated in Fig. 6.

As for valve 139, when the hand lever 143 is moved toward the operator the valve 139 is shifted so that pressure oil passes through the pipe 188 to cause a downward movement of the piston 91 of cylinder 98 to rock the swing frame grinder unit in a counter-clockwise direction (Fig. 1) about the axis of the stud 53 to depress the grinding wheel 58. When the lever 143 is moved away from the operator, fluid is passed through the pipe 103 to cause an upward movement of the piston 91 so as to rock the swing frame grinder unit 56 in a clockwise direction about the axis of the pivot stud 53 and raise the wheel.

As for valve unit 138, when the hand lever 142 is moved toward the operator, oil is passed through the pipe 82 to cause a movement of the piston 76 toward the right (Fig. 7) to cause a swinging movement of the column 50 about the axis of the rock shaft 49 in a counterclockwise direction. When the lever 142 is moved away from the operator oil is passed through the pipe 85 to cause a swinging movement of the column 58 in a clockwise direction about the axis of the rock shaft 49.

When the lever 141 of valve unit 137 is moved toward the operator, fluid pressure is passed through a pipe 211) to the fluid motor 23 to cause the carriage 12 travel along rails 1011 and to traverse the grinding wheel 58 in one direction relative to the billet '70. During this movement fluid exhausts from the other side of the fluid motor 23 through a pipe 211. Similarly when the lever 141 is moved away from the operator oil is passed through the pipe 211 to the fluid motor 23 to rotate the drive shaft thereof in reverse direction, reversing the carriage travel and thereby imparting a longitudinal traverse movement of the wheel 58 in the reverse direction relative to the billet 70.

By manipulating the hand levers 141, 142, 143, 144 which are conveniently located in front of the operator on the platform, the operator can in substantial measure simulate the operation now laboriously obtained by manually and physically shifting, reciprocating, pulling and pushing, tilting and pressing the handle-bars of known types of swing frame grinding machines. With a workpiece such as a billet 79 suitably positioned, as on the work support 71, the push button 175 is first actuated to start the fluid pump motor 132 and then switch 177 is actuated to start the motor 62 to drive the grinding wheel 58.

The hand lever 141 of valve 137 is then manipulated to traverse the carriage 12 longitudinally of the billet 70, in either direction, to locate the grinding wheel 58 in position above the billet surface to be ground, as in Figures 1 and 2. The push button 170 is then actuated to set into action the reciprocating motor 115-116 to give a continuously reciprocating sweep-like movement of the grinding wheel toward and away the person viewing Fig. l, and hence relatively rapidly (compared to the traverse movement which the carriage 12 gives the wheel 58 lengthwise of the billet 70), through a relatively short reversing stroke, such as for example, 2 or 3 feet.

The operator then manipulates lever 142 of valve 138 to pivotally shift the column 50 (clockwise or counterclockwise in Fig. 1) to locate the wheel 58 at the left edge (in Fig. l) of the top face of billet 70 or at the right edge or even intermediate thereof, thus to locate the line along which the wheel 58 is to move, parallel to its axis, as it is reciprocated by the action of reciprocatlng motor 115-116 and solenoid valve 146.

The lever 143 is then manipulated to actuate piston motor 98-91 to cause the swing frame grinder unit 56 to swing downwardly about the axis of the rock shaft 53 (Fig. l) yieldingly to maintain the grinding wheel 58 in operative engagement with the surface of the workpiece 70 as the grinding wheel 58 oscillates or reciprocates as above noted, longitudinally of the billet 70 (Fig. 2), the strokes being parallel to the line of rails 10, 11. Though cylinder 115 and piston 116 cause a pivoting of the plate 45 about the axis of frame rod 36 (Fig. 3) and also of the column 50, the swing frame grinder unit 56 at the lower end of the latter gives the wheel 58 a straight line motion due to the yielding action of the piston 91 in cylinder 90 and due to the spring connections 94, 95 (Fig. 4). Therefore the grinding wheel 58 reciprocates longitudinally along the top surface of billet 7ft in a substantially rectilinear path, assuming that the billet surface being ground is plane though the grinding wheel 58 follows up and down variations in the plane of the billet surface due to the manner in which it is held or pressed down against the billet surface as herein described and does not move in an arcuate path even though the lower end of column 50 does.

After a longitudinal portion of the work has been ground, the hand lever 142 is actuated to energize piston motor 75-76 to cause a small swinging movement of the column t: about the axis of shaft 49 (Pig. 1) to advance the position of the grinding wheel toward or away from the operator in Fig. l to determine the next line of reciprocation for grinding the next increment of the surface of the work-piece 79. In this manner, the reciprocating grinding wheel 58 may be advanced step by step from one longitudinal top edge of billet 70 to the other; an area may thus be ground in successive increments. That area may be shorter than the length of the billet. In that case, hand lever 141 may be actuated to shift carriage 12 along rails 10, 11 and longitudinally of the billet to bring the grinding wheel 58 into operative relation to a next adjacent area of the billet top face and the above steps of step-by-step feed repeated.

By providing a relatively short reciprocatory stroke, the operator riding on the control station 42 may visibly observe the action of the grinding wheel 58 so that if more or less grinding is desired to remove seams or cracks from the billet this may be done in the localities desired.

If desired, a plurality of spaced work-pieces, such as a number of billets arranged in succession or in line, may be ground. The surface of the first work-piece is ground to the desired extent, after which the carriage 12 may be shifted along rails 10, 11 to bring the grinding wheel 58 into operative relationship with the next work-piece to be ground and the grinding operation may then be repeated, as above described, on the next work-piece.

In a snagging operation of this type, it is sometimes desirable to shift from the usual application of the peripheral face of the grinding wheel against the billet surface to applying thereto and utilizing a corner portion at either side of the peripheral face to perform the grinding operation. In that case, hand lever 144 is suitably manipulated to control the actuation and atrest position of piston motor 1il5106 (Fig. 3) to tilt the swing frame grinder unit 56 about its longitudinal axis to desired extent so that the grinding wheel 58 is in a plane making the desired angle, other than degrees, to the billet surface. Reverse shift, and restoration to normal, are easily effected.

Wide flexibility of operation is thus possible; the above described sequences are illustrative and may be widely varied according to the needs of the grinding job and the judgment of the operator. The operator is relieved of heavy manual burdens and physical exertions, yet I have found it possible still further to facilitate and case his handling of the apparatus and to provide for better grind ing performance on the billets and greatly lessen the areas in which the above type of apparatus require the operator to be constantly on the alert. In this manner, risk of r nerve fatigue can be greatly reduced or eliminated, and

nerve energies can be etter concentrated on the peculiar requirements which varying surface compositions and hardness as well as irre ularities in the surface itself, in these steel billets, impose upon a snagging grinder opera tion. Also, it is possible to simplify sequences of opera tion, all without sacrifice of wide flexibility and adaptability to the grinding requirements.

Referring first to Fig. 7, 1 provide a solenoid actuated piston-type of control valve 210 having connections by pipes 211 and 212 respectively to the oil supply pipe and to the return pipe 159; it also has connections by pipes 213 and 214 to the carriage drive motor 23 whereby it is connected in parallel with hand valve 137. Accordingly motor 23 may be controlled by either valve, each being constructed to be normally closed or off when in at-rest position. Solenoid valve 210 is in construction the same as solenoid valve above described, is so shown in Fig. 7, and need not be further described except to say that its two solenoids are designated S-1 and 5-2. The latter are alternately energized as later described. When solenoid S1 is energized, motor 23 is driven in a direction to move carriage 12 to the left in Fig. 3, being a drive to the left of the operator positioned on the platform 42 (Figs. 1 and 2) at the front of the machine; this carries grinding wheel 58 with it and will be referred to hereinafter as grinding traverse or traverse to the left, meaning the operators left. With the billet 70 positioned parallel to the rails 10, 11 as in Figs. 1 and 2, such drive moves the grinding wheel lengthwise of the billet in one direction. When solenoid 5-2 is energized, motor 23 is reversed and carriage 12 moves to the right in Fig. 3, being a drive to the operators right; this carries grinding wheel 58 with it and will be referred to as grinding traverse or traverse to the right, the operators right. Grinding wheel 58 is thereby moved lengthwise of the billet in reverse direction. The operator on platform 22 partakes of similar movements so that he can always be in the best position to observe and watch the grinding wheel action, a position more or less in front of the billet 70 and grinding wheel 58.

Suitably mounted on the operators platform structure,

as in a panel carried in front of the hand valve assembly 137, 138, 139, 140 (Fig. 2), are two insulated knobs 217 and 218, located preferably in front of hand valve 137 (which hand-controls the carriage or traverse motor 23); each hand knob is shiftable, preferably by reversible rotary shift or motion and, as later described, each coacts with and is a part of a variable or potentiometer resistance unit and by them the operator may set the limits or length of the reversible grinding traverse movements of carriage 12 with its grinding wheel 58, all in relation to the length of the billet 70, for co-action with the variable or potentiometer resistance unit HP (Fig. 7) above briefly described and mounted for drive by carriagecarried pinion 43 from rail-carried rack 44. Hand valve 137 is in at-rest or stand-by position.

Carriage 12, the operator, and grinding wheel 58 can thus partake of repeated leftward and rightward traverse movements to move the grinding wheel 58 from one end of the billet 70 to the other (or from one end of any selected longitudinal area or portion of the top face of H the billet to the other end thereof); the rate of grinding traverse, suited to the character of the work-piece, may be set by needle valve 219 in the return pipe 212 (Fig. 7). Pressure of grinding contact between wheel 58 and the billet 79 is effected and maintained, during these traverse movements, by piston motor 9091 and is yieldably applied through the springs 9495 (Figs. 4 and l).

Illustratively, in commencing a billet-grinding operation, the first traverse stroke of grinding wheel 28 can be along the longitudinal front edge of top face of billet 70, being the edge nearest the operator (left-hand edge in Figs. 1 and 2).

Before describing circuit arrangements and co-actions between the potentiometer resistances above mentioned, it is desirable first to describe other parts and elements inasmuch as they are preferably interrelated with the above grinding traverse and its control. Thus, referring to Fig. 7, for piston motor 75-76, which may be controlled by hand valve 138 at the operators station platform 42, I provide for its actuation independently of hand valve 138 (which may be left in at-rest or stand-by position) to achieve cross-feed shift thereof in controllable increments, timed with the reversible grinding traverse movements of carriage 12 and grinding wheel 58. Preferably, I employ a solenoid actuated piston type of valve 220 having connections by pipes 221 and 222 respectively to the oil pressure supply pipe 135 and to the tank-return pipe 159; in construction valve 220 is the same as solenoid valve 145 above described, it is shown in Fig. 7, and need not in its details be further described. Its solenoids are indicated at S5 and 8-4.

Valve 224 has connections by pipes 225 and 225 to the respective cylinder chambers 227 and 228 of a motor having a cylinder 229 with reciprocable piston 230 and piston rod 231. As is later described, solenoids 8-4 and S5 are alternately energized in timed relation with the successive reversible grinding traverse movements of carriage 12 and grinding wheel 58; during leftward traverse of the latter, solenoid S-5 is and remains energized and solenoid S-4 de-energized, and during rightward traverse solenoid 8-4 is and remains energized and solenoid S5 tie-energized. Accordingly shift of piston 230 occurs concurrently with changeover or shift in energization of the solenoids S4 and S-S, at the ends of grinding traverse movements of the carriage 12.

Piston rod 231 is connected to piston rod 233 of a piston pump having a cylinder 235 and piston 236 and to either side of the latter are cylinder chambers 237 and 238 connected by pipes 241 and 242 and check valves CV1, CV-2, CV-3 and CV-4, arranged as shown in Fig. 7, to the pipes 82 and 85 that lead to the piston motor 7576; these check valves and connections insure that the oil flow in the output of pump 236235 is unidirectional even though the piston 236 thereof partakes of reversible strokes of movement, one stroke in one direction when energization shift-over is from solenoid 8-4 to solenoid S5 and another stroke in reverse direction when shift-over is from solenoid 5-5 to solenoid S-4. In either case, a single stroke of pump 235236 takes place to force a corresponding volume of oil from the pressure side of piston 236 through pipes 241 and 82 into chamber 83 of cross-feed motor -76 and cause a like amount of oil to return from its other chamber 84 via pipes 85 and 242 to the cylinder 235 at the low pressure or suction side of the piston 236. A throttle valve 241) may be set to fix the rate of this oil interchange. Rate may also be set by adjustable throttle valve 243 in the return line 222 of solenoid valve 220. Piston 76 of motor 75-76 is thus shifted downwardly to the right in both Figs. 7 and l, tilting column 58 away from the operators station 42 (to the right in Pig. 1 by a very small angle to shift grinding wheel 58, which as above assumed started its first grinding traverse movement at the front longitudinal edge of the top face of billet 70 (edge nearest the operators station), rearwardly and in a direction away from the operators station (to the right in Figs. 1 and 2) by a suitable increment which is an increment of feed in that thereby the next grinding traverse stroke or movement of the grinding wheel 58 is along a path parallel to but spaced from the path of the preceding traversing stroke. In this manner, crossfeeding may be effected, one step, in the illustrative embodiment, for each grinding traverse of the grinding wheel.

Each step or increment of cross-feed is preferably of the same magnitude; this is assured in the described arrangement in that, for each of the reversing strokes of pump motor piston 230, the pump 235236 delivers the same quantity of oil unidirectionally to the intended cylinder chamber of cross-feed motor 7576. The magnitude of these cross-feed increments may be changed by change of the measuring action of pump 235236, as by change of the length of stroke of its piston 236. This may be achieved by any suitable means interposed between the pump and its driving motor; illustratively, pump stroke may be changed by suitable adjustable stops actingupon the pump piston and piston rod, such as collar stops 246 and 247 threaded onto the adjacent ends of cylinders 231 and 235 whereby, upon turning them, the axial spacing between them is changed and they correspondingly limit the piston stroke length by co-action therewith of a disk-like member 248 carried fixedly by the aligned connected piston rods 231-233. Any other suitable means may be employed to change the volume of oil served to the cross-feed motor 7576.

The range of total cross-feed, that is, the sum of the above cross-feed increments, illustratively one for each grinding traverse of carriage 12 and grinding wheel 58, should be just about equal to the narrower dimension of the billet top face as viewed in Fig. 2; this the operator determines at his station platform 42 and it is variably determinable inasmuch as billet or other work-piece faces to be ground can vary in dimensions. In front of hand valve 138 and adjacent traverse control knobs 217 and 218 above described, I provide another set of two insulated and preferably rotatable knobs 257 and 258 of which as later described coacts with and is a part of a variable or potentiometer resistance device which in turn co-acts with a potentiometer resistance device RP which is actuated or varied in response to the successive cross-feed increments of movement imposed upon the grinding wheel 58; device RP comprises a cylindrical housing (see Fig. 7) Within which is insulatingly carried a helix of resistance wire with a shiftable or slide contact controlled by reversible axial movement of a plunger 251 mechanically connected to translate cross-feed movement of wheel 58 both directionally and quantitatively into an electrical quantity.

Thus, it may be mounted on the carriage 12 adjacent the rock shaft 49 which is actuated by cross-feed motor 75-76 and its plunger 251 connected by link 252 (Fig.

13 7) to a suitable extension 81a of rock-lever arm 81 to which motor piston 76 is connected.

I make provision for selectively determining certain automatic change in the action of the apparatus when the sum total of cross-feed increments, either from the front edge of billet 70 to the back edge or vice versa, has taken place as determined by the settings, at the operators station, of the slide- wire control knobs 257 and 258 and the coaction therewith, as later described, of the variable resistance device RP; that sum total is achieved by step-by-step shifts of the grinding wheel 58, by motor 75. When either edge is reached, 1 may achieve automatic reversal of step-by-step cross feed, or automatic retraction of the grinding wheel from the workpiece coupled with halting of traverse movements of the carriage 12 and cross-feed movements of the grinding wheel 58.

As above noted, the measured output of cross-feed prunp 235-236 (Figure 7) is unidirectional, due to the arrangement of check valves CV-l, CV2, CV3, and CV-4; between the cross-feed pump 235-236 and the cross-feed motor 75, I provide a spring-balanced solenoidcontrolled valve 260; in construction it is the same as solenoid valve 145 earlier above described, and is so shown in Figure 7. It is interposed in pipe lines 241 and 242 and has two solenoids S6 and S-7; when the latter are de-energized, the springs center the piston valves and oil supply to motor 75 from cross-feed pump 235-236 is cut off. When only solenoid S6 is energized, the unidirectional measured output, via pipe 241, of pump 235-236 is connected to motor chamber 83 for stepby-step cross-feed of grinding wheel 58 from the front edge of the billet toward the back edge; when only solenoid 8-7 is energized, the measured output, via pipe 241, of pump 235-236 is connected to motor chamber 84 for step-by-step cross-feed of grinding wheel 58 from the back edge of the billet toward the front edge. In each case, the opposite motor chamber is connected, for exhaust, to the return pipe 242 leading to the measuring pump intake.

Turning now to Fig. 8, conductors L1 and L2 represent any suitable A. C. supply circuit, such as 110 volts at 60 cycles. These may be the same conductors or circuit to which, in Fig. 7, the pump motor 132, wheel motor 62, and control circuit for solenoids S-8 and 8-9 of valve 145 are connected, but these parts are for simplicity not shown in Fig. 8. The resistance wires of the device HP and those associated at the operators station with knobs 217 and 213 are shown respectively at P1, P2, and P3, connected as shown to form a bridge of the Wheatstone type and having power input terminals at v and w where the bridge is connected, through a resistance, to the secondary winding of a transformer T-l whose primary is energized from circuit L1-L2. The slider contact operated by the pinion 43 drive of device HP is shown at x and for convenience may be considered as grounded as shown. Slider contacts actuated or shifted by knobs 217 and 218 are shown respectively at a and b. With this bridge arrangement, there are two outputs, namely, at points or contacts x and a and points x and b. Point a, which is shiftable by the operator at platform 42 by knob 217, represents the limit of leftward grinding traverse of carriage 12 and grinding wheel 58; it is the point at which leftward traverse movement is to be stopped and reversed to rightward traverse and can represent the left-hand (to the operator) end of the top surface of the billet 70. In like manner, point 11 shiftable by knob 218, represents the point of stoppage and reversal of rightward grinding traverse.

Thus, to illustrate, when slide point a on resistance P2 is, for example, at a position of of that bridge input voltage which represents the end of its rightward shift, then there is zero output voltage across bridge output 2: and a if slide contact x is 55% of the bridge supply voltage from the end of rightward traverse as measured by the device HP, resistances P2 and P3 being equal. At other positions of contact x, there is a voltage across a and x (or a to ground) the magnitude of which is linearly proportional the deviation of location of slide contact x from the balance point and that voltage is either in-phase or out-of-phase with the line voltage depending on whether x is to the right or left of balance. Similar voltage conditions will now be seen to exist between or across bridge output points b and x (or b to ground). I now provide, for each of these two bridge outputs, a detectoramp-lifier, schematically indicated in Figure 8 at AD2 and ADS, amplified plate output thereof appearing in relays R-2 and R3 respectively.

In Figure 9, illustrative or preferred circuit arrangements for each of these amplifier-detectors are shown; the circuit there shown acts as follows: point z1 is one input terminal and point z2 is the other. In the two amplifiers AD2 and ADS of Figure 8, they are connected across the bridge outputs a-x and b-x (utilizing groundings as shown and as will be understood). Returning to Figure 9, an A. C. bridge output signal is fed to the grid of the first section of the twin triode vacuum tube VT-l, is amplified, is passed on to the second section thereof for further amplification, and then is passed on to the grid of the first section of a second twin triode VT2. The plate supply to the latter is from the secondary of a transformer T2 energized from the line L1-L2 and is of the same frequency as energizes the bridge.

If that amplified A. C. signal at the grid of tube VT-2 is in phase with the A. C. plate supply, increase in current in the plate circuit results; in that plate circuit is the relay designated in Figure 9 by the legend To Relay and by the broken lines indicating the circuit connections to the relay, this designation and diagrammatic indication being illustrative of the circuit arrangement by which any relay, of which several are specifically described hereinafter, may be controlled, and accordingly the relay armature is actuated into or is held in one position. On the other hand, if the grid signal is 180 out of phase with the A. C. plate supply, the grid is negative when the plate is positive and current flow in the plate circuit and through the relay is decreased or cut off completely, causing change in the position of relay armature.

Accordingly, by appropriate connection of the A. C. plate-voltage supplies, as to polarity, to the corresponding plate circuits of amplifiers AD-2 and AD3 of Figure 8, relays R-2 and R-3 of amplifier AD2 and AD3 can be made to respond according to shifts of slide contact x relative to the two balance points a and 1). Relay R2 remains in one position, open, so long as slide contact x is to the left of balance corresponding to point a; as it moves (by rack 44 and pinion 43) in response to rightward (left-to-right in Figure 3) grinding traverse of carriage 12, it quickly reaches bridge balance corresponding to point a (the operator having set knob 217) and at that balance point or slightly beyond, relay R2 is actuated, closed, and remains so for so long as carriage 12 and contact point x remain to the right of balance point a. Similarly, relay R-3 of amplifier AD3 remains in one position, open, so long as slide contact x is to the right of balance corresponding to point b; as it moves in response to leftward (right-to-left in Figure 3) grinding traverse, it quickly reaches bridge balance at point b (previously set by knob 218 to fix the limit of rightward grinding wheel traverse) and at or slightly beyond this balance point, relay R-3 is actuated, closed, and remains so far so long as carriage 12 and contact point x remain to the left of bridge balance corresponding to point b. So long as carriage 12 and wheel 58 move between the selected travel limits corresponding to the two balance points a and [1 set by knobs 217 and 218, both relays R-2 and R3 are closed; as the lefthand balance or limit point a is reached or slightly passed, relay R-2 opens, leaving relay R-3 closed and as the right-hand balance 15 or limit point b is reached or slightly passed, relay R-3 opens, leaving relay R-2 closed.

The polarities of the A. C. plate supplies of the two detector-amplifiers AD2 and AD3 may be interrelated as indicated in Figures 8 and 9; the transformer T-2 (in Figure 8) has a secondary winding with a mid-point 1-6 and connected so that one half, via terminal z4, supplies A. C. plate voltage to the plate-relay circuit of one amplifier and the other half, via terminal z5, supplies it to the other in opposed phase, that is, 180 out of phase.

Consideringfirst traverse control of grinding wheel 58 and carriage 12, let it first be assumed that they are located at an intermediate point in the traverse stroke lengthwise of the top face of billet 70 and that they are travelling to the right (in Figure 3); this location and movement are electrically translated in the circuit arrangement of Figure 8, in the multiple A. C. Wheatstone bridge comprising the carriage-controlled slide contact x on resistance wire P1 of the device HP (Figure 7) and the operator-set, by knobs 217 and 218 at the travelling station 42, slide contacts a and b of resistance wires P2 and P3 which fix the travel limit points at which respective bridge-balancings can occur. The detector-amplifiers AD2 and AD3 respond accordingly, as do their respective output-responsive relays R-2 and R-3 which are both closed; they connect thereto by circuits 261 262 and 263264, respectively; both relays R-2 and R4: are closed at their respective contacts which are in circuit respectively with relays R-12 and R-13 and with the respective contacts 12a and 12b of relay R-12 and contacts 13a and 13b of relay R13, all as shown in Figure 8. As is also shown in Figure 8, contacts 13a of relay R-13 and contact 12a of relay R-12 are normally closed, that is, when their respective relay windings are de-energized, and contacts 13b of relay R-13 and contact 1217 of relay R-12 are normally open. Under the above conditions, with both relays R-2 and R-3 closed and only one of relays R-12 and R-13 is closed, namely relay R-13, the other relay R12 being open. Relay R12 is open-circuited, even though relay R2 is 'closed, at open contact 12b and at contact 13a which is held open by relay R13.

Relay R-13 has another contact, namely contact 130 which is normally open, but is closed upon energization of relay R13. This contact 130 is in circuit with solenoid winding S2 of valve 210 (Figure 7) and solenoid winding S--5 of valve 220 (Figure 7), the two windings being conveniently connected in parallel as shown (Figure 8) for conjoint control by the relay contact 13c. With these solenoids energized, valve 210 is held in position to drive traverse motor M in a direction to effect carriage and grinding wheel traverse movement from left to right (as seen by the operator on station 42) and valve 220 is held in position to hold pump-motor piston 230 at one end of its previous stroke, thus holding grinding wheel 58 in the position corresponding to the previous cross-feed setting thereof by motor 75.

As carriage l2 and wheel 58 continue rightward traverse, shifting contact point x on resistance wire P1, they reach and slightly pass beyond the right-hand travellimit'and bridge-balancing point as determined by setting of contact b, whereupon relay R-3 is tie-energized and opens, relay R-2 remaining closed. Accordingly, relay R-lS is de-energized at the now-open contacts of relay R-3, opening contact 130 to de-energize value solenoids 5-2 and 5-5. However, when relay R-13 de-energizes, contact 13a closes to permit current flow from line L1, closed contact 13a, closed contacts of relay R2 (still energized), relay winding R-12, to line L2, thus energizing relay R12 which closes its normally open contact 1212 to maintain its energization and which opens its normally closed contact 12a to interrupt the circuit of open contacts of relay R-3. The energization of relay R12 closes its relay contact 120 in circuit with solenoid winding Sl of valve 210 (Figure 7) and solenoid winding S4 of valve 220, the two windings being conveniently connected in parallel as shown (Figure 8) for conjoint control by the relay contact lZc. Solenoid Sl shifts the piston valves of valve 210 to reverse the drive of carriage traverse motor M to start a grinding wheel traverse strokeleftward; at the same time, solenoid S4 shifts the piston valves of valve 220 to give the piston motor 230-231 a single stroke so that the measuring pump 235-236 supplies an additional measured quantity of oil to chamber 83 of feed-stroke motor 75 and thus set the grinding wheel to a corresponding incremental advance position which it holds during the leftward traverse stroke. During these actions the reversing valve 260 remains unmoved, as will later be seen; that is, its solenoid S6 remains energized to hold the piston valves so that measuring pump 235236 will supply, at the end of each grinding wheel traverse stroke, a measured quantity of oil to chamber 83 until the back edge of the billet 76 is reached.

Since the reversal of grinding wheel traverse takes place slightly beyond the balance point, in the above illustration, slightly to the right of balance point determined by the slide contact b, reverse shift of slide contact x on resistance wire P1 means a leftward passing of the carriage 12 and grinding wheel 58 from a point slightly to the right of balance point b, through the balance point b, and thence on leftward to and slightly beyond the other limit or balance point a. As slide contact x passes leftward through the balance point b upon commencement of leftward grinding wheel traverse, relay R3 closes (relay R-Z being closed), but since relay R-13 is de-energized and relay R-12 is energized, circuit conditions remain the same, that is, relay contact 12c remains closed to maintain valve solenoids S1 and S4 energized and the circuit of relay R-13, even though relay R-3 closes its contact, remains held open at contact 12a of energized relay R12. Accordingly, carriage 12 and grinding wheel 58 reach the other travel limit as electrical-1y translated by the relation of slide contact x to left balance point a, then relay R2 is deenergized and opens, relay R-S remaining closed. When relay R2 opens, relay R-12 is de-energized at the nowopen contacts of relay R-2, opening contacts to deenergize valve solenoids S1 and S4; but upon deenergization, relay R-lZ closes its contact 12a to permit current to flow from line L1, closed contact 12a, closed contacts of relay R-3 (still energized), relay winding R13, to line L2, thus energizing relay R43 which closes its normally open contact 13b to maintain its energization and which opens its normally closed contact 13a to interrupt the circuit of open contacts of relay R2. The energization of relay R-13 also closes its relay contacts to energize valve solenoid windings S2 and SS of which the former etfects reversal of the carriage motor M to start a rightward traverse stroke of travel of carriage 12, the operator, and grinding wheel 58 and of which solenoid SS, by shifting valve 220, efiects a stroke of movement of piston motor 230231 to cause the measuring pump 235236, through cross-feed motor 75, to set the grinding wheel 58 one increment of crossfeed nearer to the back edge of the billet 70, for the ensuing rightward traverse of the wheel 58.

These sequences repeat themselves, as will now be clear. As cross-feed by motor 75 progresses step-bystep, the slide contact y, shown in Figure 8, of the device RP that is actuated step-by-step by the cross-feed motor 75 (see Figure 7 is shifted in relation to its associated resistance wire P4 (see Figure 7) and in relation to the positions of slide contacts c and d as set manually by the operators hand knobs 257 and 258, along their respective resistance wires P6 and P7.

Resistance wires P4, P6 and P7 are connected as shown in Figure 8 to form a Wheatstone type of bridge, with detector amplifiers and relay arrangements very much tht same as those above-described in connection with the resistance wires P1, P2 and P3, having power input terminals at v1 and w-1 at which the bridge is connected, through a resistance, to another secondary winding of the above-described transformer T-1. The output across y and c and the output across y and d of this bridge arrangement are connected respectively to the inputs of detector amplifiers AD6 and AD7 (again utilizing groundings as shown and as will now be readily understood), these amplifiers being the same as or similar to the amplifiers AD2 and AD3 above-described, each comprising suitable circuit arrangements and tubes such as shown in Figure 9 and also earlier above-described. The A. C. plate supplies of amplifiers AD6 and AD7 are provided by the respective halves of the secondary winding of a transformer T-3, like the transformer T-2, the secondary Winding being provided with a mid-point which may be grounded as shown and the end terminals of which are connected, as eariler-above described, so that one half of the winding supplies A. C. plate voltage to the plate-relay circuit of one amplifier and the other half supplies it to the plate-relay circuit of the other amplifier in opposed phase, as will now be clearly understood. The plate output circuit of amplifier AD6 is connected by conductors 265-266 to relay R-6 and the output of amplifier AD7 is connected by conductors 267-268 to relay R-7.

While the abovedescribed progressive or step-by-step cross-feed of grinding wheel 58 is taking place in the direction from the front edge of the billet 70 toward the rear edge, solenoid 8-6 of valve 260 is energized and solenoid S7 is de-energized, because both relays R-6 and R-7 are closed so long as the grinding wheel 58, in its step-by-step cross-feed and as electrically translated, in the Wheatstone bridge, by the location of slide contact y of the resistance wire P4 (of the device RP of Figure 7), is between the front edge and the back edge of the billet 70 and hence between the balance points and d. Relays R-6 and R-7 control relays R-16 and R-17 respectively, and during the just described condition of the parts, relays R-6 and R7 being closed, relay R-17 is energized and relay R-16 is de-energized; relay R-16 is de-energized because, though the contact of relay R-6 is closed, its circuit is held open at contact 170 of relay R17. Relay R-17 has another contact 17b which it holds closed to maintain its own circuit, the parallel contact 16a of relay R-16 being open. Relay R17 has another contact 170 which is in circuit with solenoid winding 8-6 to maintain the latter energized, its companion solenoid S7, of this valve 260, being de-energized in that its circuit is held open at contact 16c of de-energized relay R16.

As the step-by-step cross-feed progresses and reaches the rear edge of billet 70, slide contact y on resistance P4 reaches and slightly passes beyond the bridge-balancing point as determined by the setting of slide contact d, by hand-control 258, whereupon relay R-7 is de-energized and opens, relay R-6 remaining closed. Accordingly, relay R-17 is de-energized at the now-open contacts of relay R-7, opening contact 170 to de-energize solenoid S6, permitting the piston valves of valve 260 to seek a center position. When relay R-17 de-energizes, it also opens its contact at 17!) and closes at contact 17a to permit current flow from line L1, closed contact 17a, closed contacts of relay R-6 (still energized), relay winding R-16, to line L2, thus energizing relay R-16 which closes its own normally-open contact 16b to maintain its energization and which opens its normally-closed contact 16a to interrupt the circuit of open contacts of relay R-7. Relay R-16 also closes its normally-open contact 160 which is in circuit with the other solenoid S7 of valve 260 (Figure 7) so that solenoid S7 energizes and shifts the piston valves of valve 260 to reverse the connections of the unidirectional output of pump 235-236 to the chambers of motor 75 whereby subsequent strokes of the pump supply oil unidirectionally to chamber 84 of 18 motor 75, thus causing the cross-feed increments of grinding wheel 58 to take place in reverse direction, namely from the rear edge of billet it) toward the front edge.

The slides y having reversed the direction of crossfeed increments after having gone slightly beyond balance point a, the subsequent shift of slide contact y partakes of step-by-step shifts in reverse direction, passing balance point d in reverse direction and thus energizing relay R7, relay R6 bein already closed, and both relays remain closed until the other balance point 0 is reached and slightly bypassed. Though relay R-7 closes as just described, relay R-17 remains de-energized because its contact 17b is a normally-open contact and the energizing circuit of relay R-17 is held open at the nowopen contact of energized relay R-16.

Successive reversing traverse movements of the carriage 12, with the operator on platform 42, and of the grinding wheel 58 continue as before, under the control of relays R-2 and R-3, with a cross-feed increment, through motor 75, given to the grinding wheel 58 at the end of each traverse stroke, as before, but now with the cross-feed increments progressing from the back edge of the billet toward the front edge, since only solenoid S7 of valve 260 is energized and the measured quantities of oil from pump 235-236 are supplied to chamber 84 of motor 75, until the sum total of the cross-feed increments brings the grinding wheel close to the front edge of the billet 70, being the left-hand edge as seen in Figures 1 and 2.

When that happens, being translated by shift of slide contact y along the resistance wire P4, of the device RP of Figure 7, the balance point c is reached and at that point or slightly beyond relay R-6 is de-energized and opens, relay R-7 remaining closed. When relay R-6 opens, relay R-16 is de-energized at the now-open contacts of relay R6, opening contacts 160 to de-energize valve solenoid S7 of valve 260; but upon de-energization relay R-16 closes its contact 16a to permit current to flow from line L1, closed contact 16a, closed contacts of relay R-7 (still energized), relay winding R-17, to line L2, thus energizing relay R-17 which closes its normallyopen contact 17b to maintain its energization and which opens its normally closed contact 17a to interrupt the circuit of open contacts of relay R-6. The energization of relay R-17 closes its contact 17c to energize solenoid 8-6 of valve 260, thus to reverse the direction of crossfeed increments so that they take place from the front edge of the billet toward the rear edge.

In this manner the entire area of the top face of billet 70 may be gone over as many times as may be desired; during each treatment or grinding operation upon the billet face, the carriage 12 and grinding wheel 58 partake of reversing traverse movements each at appropriate speed or rate of movement to give the grinding Wheel appropriate time to do its cutting for each increment of cross-feed, one increment for each traverse movement. With the arrangement just described, direction of crossfeed is reversed for successive grinding operations performed. At any time and during any traverse movement, the operator may efifect tilting of the grinding wheel, to bring either corner into concentrated grinding action, by manually actuating the handle 144 of hand-valve 140, in order to actuate and control the hydraulic motor (Figure 7) which, as is better shown in Figure 3, tilts the swing frame part 56a about its axis to give the desired angularity of the plane of the grinding wheel 58 to the plane of the top face of the billet 70. Pressure of contact of the grinding wheel 58 with the working-piece or billet 70 is under the control of hydraulic motor 90, which applies the grinding pressure through the springs 94-95 above described and shown in Figures 4, 3 and 1; motor 99 is also manually controllable, as earlier described, by lever 143 of hand-valve 139, at the operators station at platform 42, and in this manner the operator can set motor 90 for an entire grinding treatment or grinding operation and during any stage of the latter can, by the same hand-valve, alter or vary the grinding pressure and, according to the condition of the surface being ground, he can cause grinding to take place at more or ess grinding pressure at one point or area than at another. Standing on and travelling with the platform or station and thus partaking of the traverse movements of the grinding wheel 58, the operator can, in this manner, supervise and alter the grinding action of the grinding wheel as his judgment with respect to the conditions of the surface being ground dictates.

Desirably, however, I arrange or provide for controls for automatically halting the apparatus at the completion of the sum total of increments of cross-feed from one edge of the face of the Work or billet to the other. This arrangement of controls I may, and preferably do, provide in a manner so as to be selective at will relative to the continuous or repetitive operating arrangement above described, so that either may be made effective by the operator. But in so providing selectivity, it is to be understood that except as stated in the claims herein, I am not to be limited to such selectivity in that either arrangement may be employed independently of the other, though, as. will be presently seen, there are many ad vantages to be gained, by practical and relatively simple interrelationship as are about to be described, in making provision for dependable and facile selection of either, in the same installation or equipment.

I have above described how piston-and-cylinder hydraulic motor 90 may be operated and controlled, by the station-located hand-operated valve 139143, to bring the grinding wheel 58, by pivoting bracket 54 which carries the swing frame 56, about the axis of shaft 53 (Figures 1 and 3) that is carried at the lower end of column 5%), toward and into contact with the work-piece or billet 7% or away from and out of contact with the work-piece as well as to control the pressure of grinding contact between the grinding wheel 58 and the workpiece. Now, 'I provide a solenoid-and-spring controlled valve 270 of the piston type for also controlling motor 9i). As shown in Figure 7, the solenoid-controlled valve 270 may be constructed, being of the piston-valve type, substantially as indicated in Figure 7; it has a solenoid 8-3 operating at one end of the valve item Zhl'against a spring 282 so that, when the solenoid is de-energized, the valve stem 231 and its piston valves are in one position (down) under the action of the spring 282 and, when solenoid S3 is energized, it overcomes the effect of the spring and valve stem 281 and its piston valves are in the other operating or control position (up), the latter being illustratedin Figure 7. As shown in Figure 8, in which an illustrative circuit arrangement is shown, sol noid S3 is controlled by the'multiple Wheatstone bridge that includes resistances P4, P6 and P7, and by the coaction of bridge-responsive relays R-6 and R-7 with relays R46 and R-17, which, through a relay R67,

determine the energization and de-energization of solenoid S-3. v

Thus, solenoid 8-3 maybe bridged across line wires L1 and L2 in a circuit from line L1, conductor Z84, solenoid winding S41, normally-closed contacts 67a of re lay R-67, and conductor 285 to line L2; it thus remains normally energized with the valve parts 279 positioned as in Figure 7. Conductor 285' is preferably connected V to main line L2 on the live side of switch SW-2 and of relay contacts 67b, and the other side of relay winding R-67 is connected by conductor 287 to the blade of a single-pole double-throw switch SW-3 which may be of any suitable construction and which is located in the panel at the operators station 42, alongside of switch SW2 for example. One pole of switch SW-S'is connected by wire 288 intermediate of solenoid winding S6 and relay switch or contacts 17c of relay R17 so that, when switch SWS is thrown to the right, relay R-67 is connected in parallel with solenoid winding S6 and is energized or de-energized concurrently therewith; the other pole of switch SW-3 is connected by wire 289 intermediate of solenoid S7 and relay switch or contacts 16c of relay R-lfi so that, when switch SW-3 is thrown to the left, relay Rol is connected in parallel with solenoid winding S-7 and is energized or de-energized concurrently therewith. When switch SW-3 is in neutral or middle position, relay R67 is open-circuited, solenoid S3 stays energized, and both switches 67a and 67b stay closed.

Accordingly, let it be again assumed that the operator has set balance points 0 and d, via hand knobs 257 and 258, so as to start a grinding operation, with carriage and grinding wheel traverse and grinding wheel crossfeed as above described, beginning at the front edge (nearest the operator and his platform 42) of the billet 70, and that he desires to have this operation halted at the back edge, that is, when the sum total of the crossfeed increments, via motor 75 and its controls, brings the traversing grinding wheel to just about the back edge of the billet. In that case, upon completion of the handsettings of balance points c and d, the operator actuatcs switch SW-3 to the left in Figure 8, thus connecting relay R-67 in parallel with solenoid 5-7 of the cross-feedreversing valve 260. Since incremental or step-by-step cross-feed is in the direction from the front edge of billet toward the rear edge, solenoid s-s of valve Ztitl is energized and solenoid 8-7 is de-energized and with relay R67 in parallel with the latter, it too is de-energized, leaving solenoid S3 energized at contacts 675:; this condition continues until the back edge of the billet and the back balance pointd are reached, the latter via the shift of point y on resistance wire P4 of the device RP, when, as above described, the multiple bridge P4, P6 and P7 and its related relays cause solenoid S6 to be de-enerstep-by-step cross-feed; at contact 67a, relay opens the circuit to solenoid S3 which deencrgizes and lets spring 282 shift (Figure 7) piston valves of valve 279 to supply oil to the chamber 1.32 of motor which then partakes of afull upward. stroke (Figures 7 and l} to tilt the swing frame 56 clockwise (Figure l)..abcnt pivot shaft 53, raising grinding wheel 53 completely from the Work and holding it there, subject to other controls by the operator.

direction from the back edge of the work toward the front edge, was will now be clear. When the front edge is reached, it is solenoid 8-6 that becomes energized and with it also relay R-67, thus to de-energize solenoid S3 of valve 270 to effect raising of the grinding wheel and at its switch contacts 67b to open-circuit the solenoids of valves 210 and 220 to halt other movements.

If switch SW3 is left open at the commencement of grinding, the apparatus will, as above described, traverse carriage 12 and grinding wheel 58 back and forth lengthwise of the billet 70 with accompanying step-by-step cross-feed the direction of which is automatically reversed when the sum total of feed increments brings the grinding wheel to either the front edge or the back edge of the work piece. During any stage of such repetitive grinding operations, switch SW3 may be closed in one direction or the other, according to the direction of cross-feed, if the operator wishes automatic halting and grindingwheel withdrawal to take place at the edge toward which cross-feed progresses the grinding wheel step-by-step; if progression is toward the back edge, switch SW3 is thrown toward the left and if progression of cross-feed is toward the front edge switch SW3 is actuated toward the right in Figure 7. In each case relay R-67 is connected in parallel with that solenoid, either S6 or 8-7, that stands de-energized during cross-feed progression. On the other hand, switch SW3 may be used to halt the operation and retract the grinding wheel, during any crossfeed progression of the grinding wheel, by its actuation reversely from the above to connect relay R-67 to that solenoid, either S6 or -7, that stands energized during cross-feed progression, in which case wheel retraction immediately takes place because solenoid S3 is thereby energized and carriage and wheel traverse halted and also cross-feed in that relay switch 67b is immediately opened.

For preferred coaction with valve 270, band valve 1391 i3 of the manual valve assembly at the operators station or platform 42 is preferably constructed as shown in Figure 10, that is, instead of being spring centered as by the spring 194 as in Figure 6, it is provided with a yieldable latch or detent to hold its spool or pistons 191, 192, 193 and the valve stem 190 and the operating handle 143 in any of three positions, that is, piston valves down, pistons centered, and pistons up. Thus, I may provide, at the lower end of valve stem 190, a piston 271 having three axially spaced notches 272, 273, 274 which may be peripheral grooves as indicated in Figure 10 and with which coacts a yieldably mounted detent 275 in the form of a ball at the inner end of a round hole or channel 276 extending radially through the wall of the valve casing; the ball 275 is pressed radially inward by a spring 277 so that it takes into any one of the notches or peripheral grooves 272, 273, 274 and releasably or yieldingly holds the valve item 190 and its piston valves in any one of the correspondingly selected positions above noted. The channel 276 is closed and the compression of spring 277 is determined by a screw 278. In Figure 10, the valve is shown with its valve stem 190 and piston valves in center position, that being the cut-off position of the valves.

Recurring to Figure 7 and valve 270, when in up position (as shown) as a result of energization of solenoid S3, fluid under pressure supplied bypipe 135 is cut off from flow to and through pipe 291 which leads, through a check-valve CV-18, and branch pipe 292, to to the wheel-retracting side or chamber 102 of motor 90 and to which branch pipe 292 is connected, through a check valve (IV-12 and a throttle TV-13, in parallel with check valve CV12, the outer pipe 103 from hand valve 139-143; these check valves, as indicated in Figure 7, facilitate supply of oil under pressure to the lifting side, chamber 102, of motor 90 independently under the respective controls of valve 270 and hand valve 139.

With solenoid S3 energized, and when the valve 270 is in up position, therefore, the operator may at any time, as grinding wheel traverse and cross-feed thereof take place, manipulate hand lever 143 of station valve 139 to lower the piston stem 190 with its piston valves from the mid-position shown in Figure 10 to cross-connect the port of passage 203 (to which oil supply pipe 136 is connected) and the port of pipe 103 and supply oil, through check valve CV12 and branch pipe 292 to the motor chamber 102 to relieve or lessen grinding Wheel pressure or to retract the grinding wheel upwardly from the billet 70. In such case, as the motor piston 91 moves upward, oil from upper chamber 101 of motor can freely escape via branch pipe 293, check valve CV-16 and pipe whose port in valve 139 is crossconnected by the piston valves to the port of pipe 187, which leads to return pipe 159 for discharge into tank or reservoir 130. In parallel with check valve CV-16 is a throttle valve TV-14.

Likewise, the operator may at any time, through hand lever 143, raise the valve stem 190 from the mid-position shown in Figure 10 and thereby cross-connect the port of oil-supply passage 203 (Figure 10) and port 201 of pipe 100 to supply oil to the upper motor chamber 101 of motor 90, through adjustable throttle valve TV-14 (which is in parallel with the check valve CV-16) and through branch pipe 293, thus to make effective grinding wheel pressure on the work-piece or to lower the grinding wheel to the work; in such case, as the motor piston 91 moves downward, oil from the lower motor chamber 102 can escape via branch pipe 292, throttle valve TV13, and pipe 103 whose port in valve 139 is cross-connected by the piston valves to the port of pipe 187 which leads to return pipe 159 for discharge into reservoir 130.

Aside from the ports for pipes and 291, valve 270 (Figure 7) has two other ports. One of them is connected by pipe 295 to the return pipe 159 which leads to the reservoir 130. The other has connected to it a pipe 296 in which is a check valve CV-17 and which is connected by pipe 297 and branch pipe 293 to upper motor chamber and by pipe 298, which has a throttle valve TV15 therein, to the return pipe 159.

With this illustrative and preferred interrelationship of parts, numerous advantages may be achieved. When valve stem and its piston valves, of hand valve 139 (Figure 10), is up, a position in which it is releasably held by detent 275 engaging in piston recess 274, oil moves in pipe 100 through throttle valve TV-14 both to the wheelpressure-applying side (chamber 101) of motor 90, via branch pipe 293, and to the return pipe 159, via pipe 297 and pipe 298 and the throttle valve TJ-15. By appropriate relative adjustments of throttle valves TV-14 and TV15, the rate of oy-passing of oil therethrough and to the return pipe 159 may be determined and thereby the effective pressure of oil supplied to motor chamber 101 may be set. For example, throttle valve TV-14 may be set, with valve TV-IS open, so that, say, 3 to 5% of the oil delivered by pipe 100 passes through valve TV-14; then by adjustment of valve TV15 in the direction from full open to closed, the operating pressure of the oil supplied to down-drive motor-chamber 101 may be varied or set within the range from zero to full oil-supply-line pressure. in this manner, the pressure at which motor 90, through arm 99 and bracket carrier 54 (Figure l), pivots swing frame 56 counter-clockwise and presses the grinding wheel 58 down against the top face of billet 70, acting through the springs 94 95, may be set, and with hand lever 143 moved counter-clockwise into position, in Figure 10, so that detent 275 engages in plunger recess 274 to hold valve stem 190 and its valves in up position, the selected grinding pressure is maintained throughout the operation, that is, throughout grinding wheel traverse and step-by-step feed.

When the solenoid S3 of valve 270 is de-energized, as for example at the end of cross-feed to the back edge or to the front edge of the billet 70 as in illustrations given above, the valve pistons of valve 270 move down, by spring 282, and the port of oil-supply pipe 135 and the port of pipe 291 are cross-connected so that full linepressure of oil flows, via pipe 291, check valve CV-18, and branch pipe 292, into lower chamber 102 of motor 90 and the latter promptly retracts the grinding wheel 58 upwardly, by swinging arms 99, bracket 54 and swing i V pipes 293 and iii-"3,

23 7 frame 56 clockwise in'Figure l; the down position of valve pistons in valve 27% cross-connects the ports of pipes 295 and 2% so that oil can freely discharge from upper motor chamber 101 via branch pipe 293, pipe 297, pipe 2% and check valve CV47, through the abovementioned cross-connected ports, and by pipe 295 to the return pipe 159 that leads to reservoir 13% thus insuring quick lifting of grinding wheel 53 off of the work-piece. This occurs regardless of the position of hand valve 139143 (Figure 10); if the latter happens to be up to supply oil to the upper motor chamber 1% for wheelto-work pressure via pipe 1-96 and restricting throttle valve TV-lldand branch pipe 293, that oil supply is bypassed from chamber 161 via pipe 297, pipe 2% and check valve CV17, cross-connected ports in valve 27% of pipes 296 and 25 5, and by the latter to the oil return pipe 159 to reservoir I130. If hand valve 13143 happens to be down to supply oil to lower chamber 102 via pipe 193, check valve CV42 and branch pipe 292, with oil discharging from upper chamber 101 via pipe 2%, check valve CV-JLd and pipe Tide, the down position of valve 279 simply parallels oil supply, from pipe 135 and through pipe 291 and check valve CV48, to lower motor chamber 192 and the exhaust circuit from upper chamber ml is parallelled via pipe 2&7, pipe 296 and check valve CV47 and pipe 2% to the reservoir return pipe 159.

Throttle valve TVll3 serves as a flow restriction to prevent loss of pressure when solenoid 3-3 is de-energized and the piston valves of valve 27% are in down position, in that it prevents substantial by-passing of high pressure oil supply to the lower motor chamber Hi2 via pipes 291 and 2%, and in that respect valve TV-13 coacts, by its restricted'flow, in a manner not to completely shunt the check valve CV-llZ with which it is in parallel;

thus the desired rapidity of lifting the grinding wheel 58 off of the work-piece when solenoid 5-3 is de-energized is not interfered with. On the other hand a rapid raising of the grinding wheel 53 off of the work-piece may be effected by the hand valve 13-l43 when the latter is moved to its down position to supply oil to the'lower motor chamber Hi2 via pipes 193 and 292, for in the latter case the restricting valve TV13 is bypassed by the check valve CV-iZ, and at the exhaust end or chamber 191 of motor 93, oil may freely discharge via check valve CV46 shunting or bypassing the restricting valve Ti/-14.

From the foregoing, the practice of my invention and theoperation and control of the apparatus will be clear; it will be noted however that, in describing the operation of the apparatus under the control of the multiple Wheatstone bridges and associated relays, l have not made mention of the motor ftlS-lft6 and its valve 3l45 that is controlled by the solenoids 5% and 8-9, by which, under the control of the limit switches LS1 and LS2 (Figure 7) and their coacting movable actuator res, as earlier above described, this motor and its valve and controls effect a reciprocating sweep-stroke back and forth of the grinding wheel during its left and right traverse movements. Such reciprocating sweep strokes, which are shorter than the length of the billet and 'are therefore shorter than the traverse movement of carriage 12 and grinding Wheel 5%, may or may not be made to function, as the operator may desire; he may simply actuate tie off switch 171 (Figure 7) and such sweep-stroking during grinding wheel traverse movement does not take place ator may make such sweep-stroking of the grinding Wheel effective during the full automatic operation of the apparatus under the control of the multiple Wheatstone bridges and relays, etc. The rate of oscillation or reciprocation to effect these sweep strokes may be determined,

as earlier described, by setting of the throttle valve 158; the length of the sweep stroke may be determined by the provision of any suitable means for relatively adjusting the spacing between the limit switches LSZi and LS2 relative to the reciprocating switch actuator 165, and in Figure 7 the double-headed arrows alongside the limit switches LS1 and LS2 are intended to represent any suitable means for so adjustably positioning the two limit switches. In this manner the length of the reciprocating or sweep stroke may be adjusted through wide limits; for manual operation of the apparatus as under the control of the hand valves 137138-139i4il, the stroke may be relatively long as earlier above indicated, but for full automatic operation of the apparatus, it is preferred that the sweep stroke be relatively short such as for example on the order of six inches or ten inches, that length of sweep-stroking being adequate to get the advantages and effects of simulating the left-to-right and right-to-left grinding wheel movements which it is customary to employ with known types of swing frame grinders where the operator must manually, as by a pair of handle bars, convey to the grinding wheel all necessary movements as well as grinding pressures and their variations.

When the apparatus is operated under the control of the multiple Wheatstone bridge and relay arrangement, the operator, by setting the knobs 217 and 218 as above described, determines the leftward and rightward (Figure 3) limits of the grinding wheel traverse movements so that, as it is now clear, traverse movement of the grinding wheel in one direction is reversed to partake of traverse movement in opposite direction when the grinding wheel reaches the left or right (to the operator) end of the billet 76} so that the grinding wheel does not run off either edge or end; if the above described reciprocating or sweep-stroking action of the grinding wheel is also employed, the operator, in setting the traverse-limiting balance points a and b by knobs 217 and 218, takes into account the length of the sweep stroke so that traverse reversals take place at respective limit points within which is included the length of the sweep stroke of the grinding wheel in order that the latter does not run ed the end of the billet, or, the operator may, by actuating the off switch 171, halt the sweep-stroking of the grinding wheel as the ends of its strokes, as traverse continues, approach one or the other end of the billet whereupon traverse continues up to the billet end without the reciprocating action of the grinding wheel.

Though, in the description of various of the actions and controls, reference is frequently made in the above to the billet or to the top surface thereof, that is to be understood or interpreted as illustrative also of the operation and control of the apparatus where, as earlier above indicated, several work-pieces or billets are grouped together or aligned with each other, as on the Work support 71, relative to the range of travel provided by the overhead rails 1t)-11, and in such case a number of work-pieces may be subjected to the grinding operations just asthough they were a single work-piece, or

they may be subjected to the grinding operation one by one, with the range of travel provided by the overhead rails Iii-11 permitting shift of-the apparatus, when the operation on one billet is completed, to the next workpiece, the various controls for limiting or setting ranges of traverse, cross-feed, and the like permitting the operator readily and quickly, at his moving station or platform 42, to set or suit the limits electrically to Whatever particular circumstance is to be met, as by setting the handcontrols 217, 218, 257 and 253. It will thus be seen that there is available wide flexibility of operation under simple controls conveniently located with respect to the travelling operator.

To facilitate making these electrical settings there is provided, at the'operators station platform and on the 25 panel in which are mounted the various limit controls or knobs 217, 218, 257 and 258, a visual signal in the form of a gaseous discharge type of small lamp or bulb, such as a miniature neon bulb, one for each of these controls, and in Figure 8 they are indicated respectively at 217'N, 218N, 257N and 258N, each having a usual series resistor in circuit therewith; they are respectively bridged across relay contacts as shown in Figure 8 so that each becomes luminous only when the relay contacts which each shunts are open and when the amplifierrelay, RZ, R3, R6 or R7, as the case may be, is closed; these neon bulbs operate on very small current values, and the shunt which each forms about the relay contacts is of such high resistance that control of relays by the contacts is not aflected. These visual signal bulbs make it easy for the operator to initially set the respective bridge balance points, to the actual physical limits of traverse or sum total cross-feed, or the like; all the operator need do is hand-control the physical location of the grinding wheel to the desired travel limit in one direction or another, and then actuate the corresponding control knob to such point that the corresponding neon lamp or signal changes; in that manner the operator locates the travel limit balance points a and b relative to the bridge resistances P2 and P3 and the crossfeed limit balance points and d relative to the bridge resistances P6 and P7 respectively.

The slide wire resistances P2, P3, P6 and P7 of the several bridges, with their respective slide contacts, are as above noted located on or at the control panel in front of the operator on his platform or station 42, so that their respective hand-controls or knobs 217, 218, 257 and 258 are readily accessible to and in front of the operator; each is preferably constructed to form a compact unit, like the unit HP of Figure 7 in which there is an internal helix of resistance wire with a slide contact that responds to the rotary movement of the control shaft driven by the pinion 43 (for the device HP), excepting that the shaft of each device at the control panel is rotated manually, by the respective hand knobs above described, each device being provided in any suitable manner with any suitable gear-ratio of drive between the knob or its shaft and the internal rotatable slide contact.

It will thus be seen that there has been provided in this invention an apparatus in which the several objects above noted together with many thoroughly practical advantages are successfully achieved. The operator is relieved of the physical burdens of manually actuating or traversing the grinding wheel relative to the billet and of applying grinding pressure manually, and in the flexible controls I have provided, the operator can also be very materially freed of the risk of nervous fatigue for, with the bridge balance or travel limits once set at the outset, the entire work-piece surface can be ground with depend ability under simply the operators visual supervision while at any point in such a continuous grinding operation the operator can easily, by control switches or by the manual or hand-valves, all handily located in front of him, effect such changes in grinding action as any particular spot or area on the work-piece may require, followed by equal ease and convenience of shifting the apparatus back to full automatic control and operation.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.

Iclaim:

1. In grinding apparatus, in combination, means forming a support for a long work piece such as a billet, overhead guide rails extend-ing lengthwise of the support, a carriage adapted to travel therealong with reversible motor means therefor and a variable resistance deviceresponsive to oarira-ge travel to measure the latter, said carriage having an operators station depending therefrom and in front of the Work-piece support and having movably depending therefrom, to the rear of said support, a frame for movement toward and away from the operators station with reversible drive means for so moving it and with a variable resistance device responsive to its movement to measure the latter, said frame supporting a sub-assembly comprising a driven grinding wheel overlying said work-support and movable relative thereto, variable resistance means at said operators station with two manual controls therefor and having circuit-connections to said first variable resistance and forming therewith a multiple electrical bridge having two balance points settable by said two manual controls with means responsive to electrical change in relation to either of said points according to the direction of carriage travel and resultant change thereby in said first resistance device for effect-ing reversal of said carriage-driving motor means whereby said carriage with the grinding wheel and operators station travels along said overhead rails lengthwise of the work-piece in reversing grind-ing traverses relative to the workpiece that are of a length as determined by the setting of said two manual controls, means adapted to operate in timed relation to said reversing grinding traverses for actuating said frame-moving reversible drive means unidirectionally in successive relatively small increments to thereby give the grinding wheel step-by-step feed in direction from one longitudinal edge of the work-piece to the other, a second variable resistance means at said operators station with two hand controls therefor and having circuit-connections to said second variable resistance device and forming therewith a multiple electrical bridge having two balance points settable by said hand controls, control means operating in response to electrical changes in the second bridge relative to either of said points according to the direction of said step-by-step grinding wheel feed movement and resultant resistance change in said second resistance device, means for effecting reversal of said frame-moving drive means to reverse the direction of step-by-step grinding wheel feed, means operable for retracting said grinding wheel from the work piece, and manually operable means at said operators station for selectively associating said two last-mentioned means with said control means.

2. In grind-ing apparatus, in combination, means forming a support for a long work-piece such as a billet, overhead guide rails extending lengthwise of the support, a carriage adapted to travel therealong with reversible motor means therefor and a variable resistance device responsive to carriage travel to measure the 'latter, said carriage having an operators station depending therefrom :and in front of the work-piece support and having movably depending therefrom, to the rear of said support, a frame for movement toward and away from the operators stat-ion with reversible drive means for so moving it. and with a variable resistance device responsive to its movement to measure the latter, said frame supporting a sub-assembly comprising a driven grinding wheel overlying said work-support and movable relative thereto, variable resistance means at said operators station with two manual controls therefor and having circuit-connections to said first variable resistance and forming therewith a multiple electrical bridge having two balance points settable by said two manual controls with means responsive to electrical change in relation to either of said points according to the direction of carriage travel and resultant change thereby in said first resistance device for effecting reversai of said carriage-driving motor means whereby said carriage with the grinding Wheel and operators station travels along said overhead rails lengthwise of the work-piece in reversing grinding traverses relative to the workpiece that are of a length as determined by the setting of said two manual controls,

27 means adapted to operate in timed relation to said reversing grinding traverses for actuating said frame-moving reversible drive means unidirectionally in successive relatively small increments to thereby give the grinding wheel step-by-step feed in direction from one longitudinal edge of the work-piece to the other, a second variable resistance means at said operators station with two hand controls therefor and having circuit-connections to said second variable resistance device and forming therewith a multiple electrical bridge having two balance points settable by said hand controls with means operating in response to electrical changes in the second bridge relative to either of said points according to the direction of said step-by-step grinding wheel feed movement and resultant resistance change in said second resistance de vice for effecting reversal of said frame-moving drive means whereby feed movement reversal may be effected at the front and rear work-piece edges, means operable for retracting said grinding wheel from the Work piece, and manual means at said operators station selectively operable for controlling said wheel-retracting means and operable to place the latter under the control of said last-mentioned bridge-unbalance responsive means.

3. In grinding apparatus, in combination, means form- 7 ing a support for a long work-piece such as a billet, overhead guide rails extend-ing lengthwise of the support, a carriage adapted to travel therealong with reversible motor means therefor and a variable resistance device responsive to carriage travel to measure the latter, said carriage having an operators station depending therefrom and in front of the workpiece support having mov-ably depending therefrom, to the rear of said support, a frame for movement toward and away from the operators station with reversible drive means for so moving it and with a variable resistance device responsive to its movement to measure the latter, said frame supporting a sub-assembly comprising a driven grinding wheel overlying said work-support and movable re-lative thereto, variable resistance means at said operators station with two manual controls therefor and having circuit-connections to said first variable resistance and forming therewith a multiple electrical bridge having two balance points settable by said two manual controls with means responsive to electrical change in relation to either of said points according to the direction of carriage travel and resultant change thereby in said first resistance device for effecting reversal of said carriage-driving motor means whereby said carriage with the grinding wheel and operators station travels along said overhead rails lengthwise of the workpiece in reversing grinding traverses relative to the workpiece that are of a length as determined by the setting of said two manual controls, means adapted to operate in timed relation to said reversing grinding traverses foractu atin-g said frame-moving reversible drive means unidirectiona-lly in successive relatively small increments to thereby give the grindin wheel step by-step feed in direction from one longitudinal edge of the work-piece to the other, a second variable resistance means at said opera- :tors station with two hand controls therefor andihav ing circuit-connections to said second variable resistance device and forming therewith a multiple electrical bridge having two balance points settab'le by said hand'con- 'trols, control means operating in response to electrical head guide rails extending lengthwise of the support, a carriage adapted to travel therealong with reversible motor means therefor and a variable resistance device responsive to carriage travel to measure the latter, said carriage having an operators station depending therefrom and in front of the work-piece support and having movably depending therefrom to the rear of said support, a frame for movement toward and away from the operators station with reversible drive means for so moving it and with a variable resistance device responsive to its movement to measure the latter, said frame supporting a sub-assembly comprising a driven grinding wheel overlying said work-support and movable relative thereto, variable resistance means at said operators station with two manual controls therefor and having circuitconnections to said first variable resistance and forming therewith a multiple electrical bridge having two balance points settable by said two manual controls with means responsive to electrical change in relation to either of said points according to the direction of carriage travel and resultant change thereby in said first resistance device for effecting reversal of said carriage-driving motor means whereby said carriage with the grinding wheel and operators station travels along said overhead rails lengthwise of the work-piece in reversing grinding traverses relative to the workpiece that are of a length as determined by the setting of said two manual controls, means adapted to operate in timed relation to said reversing grinding traverses for actuating said frame-moving reversible drive means unidirectionally in successive relatively small increments to thereby give the rinding wheel step-by-step feed in direction from one longitudinal edge of the work-piece to the other, a second variable resistance means at said operators station with two hand controls therefor and having circuit-connections to said second variable resistance device and forming therewith a multiple electrical bridge having two balance points settable by said hand controls, control means operating in response to electrical changes in the second bridge relative to either of said points according to the direction of said step-by-step grinding wheel feed movement and resultant resistance change in said second resistance device, means operable for retracting said grinding wheel from the Work piece, and means responsive to actuation of said control means for actuating said wheel-retracting means.

5. In grinding apparatus, in combination, means forming a support for a long work-piece such as a billet, overhead guide rails extending lengthwise of the support, a carriage adapted to travel therealong with reversible motor means therefor and a variable resistance device responsive to carriage travel to measure the latter, said carriage having an operators station depending therefrom and in front of the work-piece support and having movably depending therefrom, to the rear of saidsupport, a frame for movement toward and away from the opeators station with reversible drive means for so moving it, said frame pivotally supporting a sub-assembly comprising a driven grinding wheel overiyingtsaid worksupport and movable toward or away from the latter in response to pivoting movement of the sub assembly relative to said frame, a reversible hydraulic motor operating upon said pivoted sub-assembly and operative thereon in one direction to press the grinding wheel against a work-piece on said work-support and in opposite direction to retract the wheel therefrom, variable resistance means at said operators staion with two manual controls therefor and having circuit-connections to said first variable resistance and forming therewith a multiple electrical bridge having two balance points settable by said two manualcontrols with means responsive to electrical change in relation to either of said points according to the direction of carriage travel and resultant change thereby in said first resistance device for effecting reversal of said carriage-driving motor means whereby said carriage with the grinding wheel and operators station travels along said overhead rails lengthwise of the work-piece in reversing grinding traverses relative to the workpiece that are of a length as determined by the setting of said two manual controls, means adapted to operate in timed relation to said reversing grinding traverses for actuating said frame-moving reversible drive means unidirectionally in successive relatively small increments to thereby give the grinding wheel step-by-step feed in direction from one longitudinal edge of the work-piece to the other, means including a manual control at said operators station for controlling said reversible hydraulic motor, and means including a manual control at said operators station for controlling said reversible drive means for said frame.

6. A grinding apparatus as claimed in claim 5 in which said control means for said reversible hydraulic motor comprises also means responsive to a selectable number of step-bystep wheel-feed increments of movement of said depending frame for actuating it to pivot said subassembly in wheel-retracting direction with means at the operators station for selecting said number.

7. in grinding apparatus, in combination, means forming a support for a long work-piece such as a billet, overhead guide rails extending lengthwise of the support, a carriage adapted to travel therealong with reversible motor means therefor and a variable resistance device responsive to carriage travel to measure the latter, said carriage having an operators station depending therefrom and in front of the work-piece supporting having movably depending therefrom, to the rear of said support, a frame for movement toward and away from the operators station with reversible drive means for so moving it, said frame pivotally supporting a sub-assembly comprising a driven grinding wheel overlying said worksupport and movable toward or away from the latter in response to pivoting movement of the sub-assembly relative to said frame, a reversible hydraulic motor operating upon said pivoted sub-assembly and operative thereon in one direction to press the grinding wheel against a workpiece on said work-support and in opposite direction to retract the wheel therefrom, variable resistance means at said operators station with two manual controls therefor and having circuit-connections to said first variable resistance and forming therewith a multiple electrical bridge having two balance points settable by said two manual controls with means responsive to electrical change in relation to either of said points according to the direction of carriage travel and resultant change thereby in said first resistance device for effecting reversal of said carriage-driving motor means whereby said carriage with the grinding wheel and operators station travels along said overhead rails lengthwise of the workpiece in reversing grinding traverses relative to the workpiece that are of a length as determined by the setting of said two manual controls, control means responsive to a selectable number of grinding-traverse movements of said carriage, and means responsive to said control means for actuating said reversible hydraulic motor to pivot said sub-assembly in wheel-retracting direction.

8. In grinding apparatus, 7 in combination, means forming a support for a long work-piece such as a billet, overhead guide rails extending lengthwise of the support, a carriage adapted to travel therealong with reversible motor means therefor, said carriage having an operators said overhead guide rails in reversing movements to reversibly traverse said sub-assembly lengthwise of the work support and the grinding wheel lengthwise of the work piece on the support, means adapted to operate in timed relation to said reversing grinding traverses for actuating said frame-moving reversible drive means unidirectionally in successive relatively small increments to thereby give the grinding wheel step-by-step feed in direction from one longitudinal edge of the work-piece to the other, a variable resistance means at said operators station with two hand controls therefor and having circuit-connections to said variable resistance device and forming therewith a multiple electrical bridge having two balance points settable by said hand controls, control means operating in response to electrical changes in the bridge relative to either of said points according to the direction of said step-by-step grinding wheel feed movement and resultant resistance change in said second resistance device, and means responsive to actuation of said control means for reversing said step-by-step framemoving drive means.

9. In grinding apparatus, in combination, means forming a support for a long work-piece such as a billet, overhead guide rails extending lengthwise of the support, a carriage adapted to travel therealong with reversible motor means therefor, said carriage having an operators station depending therefrom and in front of the work-piece support and having movably depending therefrom, to the rear of said support, a frame for movement toward and away from the operators station with reversible drive means for so moving it and with a variable resistance device responsive to its movement to measure the latter, said frame supporting a sub-assembly comprising a driven grinding wheel overlying said worksupport and movable relative thereto, means for controlling said carriage drive motor means to drive said carriage along said overhead guide rails in reversing movements to reversibly traverse said sub-assembly lengthwise of the work support and the grinding wheel lengthwise of the work piece on the support, means adapted to operate in timed relation to said reversing grinding traverses for actuating said frame-moving reversible drive means unidirectionally in successive relatively small increments to thereby give the grinding wheel step-by-step feed in direction from one longitudinal edge of the work-piece to the other, a variable resistance means at said operators station with two hand controls therefor and having circuit-connections to said variable resistance device and forming therewith a multiple electrical bridge having two balance points settable by said hand controls, control means operating in response to electrical changes in the bridge relative to either of said points according to the direction of said step-by-step grinding wheel feed movement and resultant resistance change in said second resistance device, means for effecting retracting movement of said grinding wheel from the work piece, and means responsive to actuation of said control means for eifecting actuation of said last-mentioned means.

10. A grinding apparatus as claimed in claim 9 in which there are provided means for halting said stepby-step frame-moving means, and means responsive to actuation of said control means for effecting actuation of said last-mentioned means, and means at said operators station for controlling said carriage drive motor means.

11. In grinding apparatus, in combination, means forming a support for a long work-piece such as a billet, an operators station substantially in front of said support whereby the longitudinal front edge of the work piece on said support is substantially opposite said operators station, a carriage having guide rails for guiding it for movement lengthwise of said support and having controllably reversible means for driving it, said carriage having movable carrier means supporting a sub-

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