US2704913A

US2704913A - Snagging grinder

Info

Publication number: US2704913A
Application number: US312715A
Authority: US
Inventors: Soderlund Carl
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1952-10-02
Filing date: 1952-10-02
Publication date: 1955-03-29
Anticipated expiration: 1972-03-29

Description

March 29, 1955 c. SODERLUND SNAGGING GRINDER 5 Sheets-Sheet 2 Filed Oct. 2, 1952 A m w L S L MW Ill: a

INVENTOR. CARL SUDER'L u vu BY M 'wom.

March 29, 1955 c. SODERLUND 2,

SNAGGING GRINDER Filed Oct. 2, 1952 3 Sheets-Sheet 3 orr 0/1. PUM

Moral? WHEEL MOTO 1m EN TOR. 4 CARI. SUDERLUND United States Patent SNAGGING GRINDER Carl Soderlund, Worcester, Mass., assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Application October 2, 1952, Serial No. 312,715

4 Claims. (Cl. 5147) The invention relates to grinding machines, and more particularly to a snagging grinder for surfaclng steel billets and the like.

One object of the invention is to provide a simple and thoroughly practical snagging grinder. Another object is to provide a snagging grinder which is arranged so that it may be operated and controlled with a minimum of manual exertion. Another object is to provide a snagging grinder in which the grinding wheel may be readily traversed longitudinally, also transversely, and may be rocked laterally through a comparatively short arcuate path for grinding small areas of the work piece. A further object of the invention is to provide a snagging grinder in which the grinding wheel may be traversed longitudinally to position the wheel relative to the work piece being ground and may be oscillated or reciprocated through a shorter stroke to grind a portion of the work piece. A further object is to provide a yieldable pressure control whereby the grinding wheel may be mamtained in grinding engagement at the desired pressure during an oscillating or reciprocating movement of the grinding wheel. Other objects will be in part obvious or in part pointed out hereinafter.

In the accompanying drawings in which is shown one of the various possible embodiments of the mechanical features of this invention:

Fig. 1 is a side elevation of the snagging grinder;

Fig. 2 is a horizontal sectional view, taken approximately on the line 22 of Fig. 1 showing the snagging grinder in elevation;

Fig. 3 is a vertical sectional view, on an enlarged scale, taken approximately on the line 33 of Fig. 1;

Fig. 4 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line 44 of Fig. 1;

Fig. 5 is a fragmentary horizontal sectional view, on

an enlarged scale, taken approximately on the line 5--5 of Fig. 1;

Fig. 6 is a vertical sectional view, on an enlarged scale, taken approximately on the line 6-6 of Fig. 7, through one of the control valves; and

Fig. 7 is a combined electric and hydraulic diagram of the actuating mechanisms and the controls of the machine.

A snagging grinder has been illustrated in the drawings comprising a pair of parallel overhead I-beams 10 and 11 which serve as a support for a longitudinally movable carriage 12. The carriage 12 is provided with a plurality of pairs of

rollers

13, 14, 15 and 16 which ride upon surfaces of the I-beams 10 and 11 and form a roller support for the carriage 12.

A traversing mechanism is provided for moving the carriage 12 longitudinally comprising a shaft 17 rotatably supported on the carriage 12. The shaft 17 is provided with a pair of driving wheels 18 and 19 (Fig. 2) which drivingly engage surfaces on 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 with a pair of

driving wheels

21 and 22 which similarly engage surfaces on the I-beams 10 and 11. 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. It will be readily apparent from the foregoing disclosure that rotary motion of the fluid motor 23 will be imparted through the link chain driving mechanism above de- 2,704,913 Patented Mar. 29, 1955 scribed synchronously to rotate the

shafts

17 and 20 thereby rotating the driving wheels 18-19 and 21-22 to traverse the carriage 12 longitudinally along the I-beams 10 and 11.

The carriage 12 consists of a pair of plates 30 and 31 (Fig. 2). The end portions of the

plates

30 and 31 are clamped around a pair of spaced transversely extending

tubular members

35 and 36. The plate 30 serves as a support for the traversing mechanism previously described and also for supporting

wheels

13 and 14 and one end of the

drive shafts

17 and 20. Similarly the plate 31 serves as a support for the

wheels

15 and 16 and also for the other ends of the

drive shafts

17 and 20. The end portions of

plates

30 and 31 surround a portion of the

tubular rods

35 and 36 and are provided with clamping plates to support the

rods

35 and 36 on the carriage 12.

A cross plate 37 is provided with enlarged

end portions

38 and 39 which surround the

tubular rods

35 and 36 respectively and are clamped thereto. The plate 37 serves as a support for a pair of spaced vertically arranged

tubular members

40 and 41, the lower ends of which support an operators control platform 42 which travels longitudinally with the carriage 12. The control platform 42 is provided with a control apparatus to be hereinafter described whereby the operating mechanisms of the machine may be readily controlled during longitudinal movement of the carriage 12.

The tubular rod 36 serves as a support for a plate 45. The right-hand end of the platen 45 has an enlarged portion 46 surrounding the tubular rod 36. The platen 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 supports a vertically arranged depending hollow column 50. The column 50 is provided with an enlarged upper portion 51 which is fixedly supported on the rock shaft 49. The lower end of the column 51 is provided with a bracket 52 which supports a rock shaft 53. The rock shaft 53 in turn supports a bracket 54 having an enlarged lower portion 55 which surrounds a cylindrical portion formed on a swing frame grinder 56. The swing frame grinder 56 may be any one of the well known commercial units having a wheel spindle 57 mounted at one end thereof. The wheel spindle 57 being arranged to support rotatable grinding wheel 58. The grinding Wheel 58 is partially surrounded by a wheel guard 59. The other end of the swing frame grinder is provided with a rock shaft 60 which 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 which are connected to V-grooves formed in the periphery of a pair of

wheel flanges

66 and 67 supporting the grinding wheel 58. An adjusting screw mechanism 68 is provided to facilitate adjusting the position of the motor platen 61 so as to tension the V-

belts

64 and 65 as desired.

A work piece such as a billet 70 to be ground is mounted on a stationary work support 71. The vertical column 50 is arranged to swing with the rock shaft 49 to cause a transverse movement of the swing frame grinder 56. The swing frame grinder 56 is arranged to swing about the rock shaft 53 so as to maintain the grinding Wheel 58 in operative engagement with the work piece 70 being ground.

A hydraulically operated control mechanism is provided for rocking the swing frame grinder 56 in a plane normal to its longitudinal axis, to rock the swing frame grinder about the axis of the rock shaft 53, to rock the column 50 about the axis of the rock shaft 49, and to rock the platen 45 about the axis of the tubular rod 36. This mechanism may comprise a hydraulic cylinder having a slidably mounted piston 76 connected to one end of a piston rod 77. The cylinder 75 is pivotally connected by a stud 78 with a bracket 79 depending from the platen 45. The right hand end of the piston rod 77 (Fig. l) is connected by a stud S6 with an arm 81 which is fixedly mounted on the rock shaft 49. It will be readily apparent from the foregoing disclosure that when fluid under pressure is passed through a pipe 82 into a cylinder chamber 83, the piston 76 will be caused to move toward the right (Fig. 7) to impart a counterclockwise swinging movement to the vertical column 50 and the parts supported thereby. During this movement fluid within a cylinder chamber 84 is exhausted through a pipe 85. It will be readily apparent that when the flow of fluid is reversed and fluid under pressure passes through the pipe 85 into the cylinder chamber 84 a clockwise swinging movement will be imparted into the column 50.

A hydraulic cylinder 90 contains a slidably mounted piston 91 which is connected to the right hand end of a piston rod 92. The cylinder 90 is pivotally connected by means of a stud 93 with a bracket 94 which is fixedly mounted on the column 50. The lower left hand end of the piston rod 92 is provided with a transversely extending stud 89 which is connected by a pair of spaced tension springs 94 and 95 with a stud 96 carried by a slidably mounted sleeve 97 (Fig. 4). A sleeve 97a surrounds the piston rod 92 and is interposed between the sleeve 97 and the pin 89 to limit the sliding movement of the sleeve 97 relative to the piston rod 92. The sliding sleeve together with the springs 9495 serve to provide a yielding connection between the piston rod 92 and the arms 98-99. The slidably mounted sleeve 97 is slidably supported on the piston rod 92. The sleeve 92 is pivotally connected to a pair of spaced

arms

98 and 99, the lower ends of which are fixedly mounted on the rock shaft 53. It will be readily apparent that when the fluid under pressure is passed through a. pipe 100 into a cylinder chamber 101, the piston 91 will move toward the left (Fig. 7) so as to rock the

arms

98 and 99 in a counterclockwise direction (Fig. 1) about the axis of the rock shaft 53 to impart a counter-clockwise swinging movement to the swing frame grinder 56. During this movement fluid within a cylinder chamber 102 may exhaust through a pipe 103. Similarly if the fluid under pressure is reversed so that it flows through the pipe 103, a clockwise swinging movement will be imparted to the swing frame grinder 56 about the axis of the rock shaft 53. It will be readily apparent from the foregoing disclosure that the tension springs 94 and 95 serve to provide a yielding connection so that the grinding wheel 58 may be yieldingly maintained in operative engage ment with the work piece 70 being ground.

A hydraulic cylinder 105 contains a slidably mounted piston 106 which is connected to one end of a piston rod 107. The cylinder 105 is pivotally connected by a stud 108 carried by the bracket 54 which supports the swing frame grinder unit 56. The right hand end of the piston rod 107 is connected by a stud 109 with an arm 110 which is fixedly mounted on the swing frame grinder unit 56. When fluid under pressure is passed through a pipe 111 into a cylinder chamber 112, the piston 106 will be moved toward the left (Fig. 7) to rock the arm 110 in a clockwise direction. During this movement fluid within a cylinder chamber 113 may exhaust through a pipe 114. Similarly if the fluid under pressure is reversed and fluid under pressure passes through the pipe 114, the arm 110 together with the swing frame grinder unit 56 will be rocked in a counter-clockwise direction about the lonigtudinal axis of the swing frame grinder unit 56. This mechanism serves to facilitate swinging the grinding wheel so that grinding may be done by either (Susie corner portion or the other of the grinding wheel A hydraulic cylinder 115 contains a slidably mounted piston 116 which is connected to the upper end of a piston rod 117. The cylinder 115 is pivotally connected by a stud 118 with a bracket 119 which is fixedly mounted on the tubular rod 35 and the carriage 12. The lower end of the piston rod 117 is connected by a stud 120 with a yoked member 121 which is rotatably supported on the rock shaft 49. When fluid under pressure is passed through a pipe 122 into a cylinder chamber 123, the piston 116 will be moved downwardly (Fig. 7) to cause a downward movement of the piston rod 117 so as to rock the platen 45 in a counter-clockwise direction about the axis of the tubular rod 36. During this movement fluid within a cylinder chamber 124 may exhaust through a pipe 125. Similarly if fluid under pressure is reversed and fluid under pressure is passed through the pipe 125, the piston 116 will be moved upwardly to cause an upward movement of the piston rod 117 thereby swinging the platen 45 together with column 50 and the swing frame grinder 56 in a clockwise direction. This mechanism just described serves to impart a longitudinal reciprocatory stroke to the grinding Wheel 58 relative to the work piece 70 being ground.

A fluid pressure system is provided for supplying flLlld under pressure to the various actuating mechanisms of the machine. In order to provide a self-contained-unit, a fluid reservoir is provided within the vertically arranged column 50. A fluid pump 131 driven by an electric motor 132 is mounted on the under side of a plate 133 which is fastened to the right hand ends of the tubular rods 35 and 36 (Figs. 1 and 2). The pump 131 draws fluid from the reservoir 130 through a pipe 134 and forces fluid under pressure through a pipe 135 to the various mechanisms of the machine. A variable pressure relief valve 136 is connected to the pipe line 135 to facilitate returning excess fluid under pressure through the reservoir 130. The fluid pressure pipe 135 conveys fluid under pressure through a pipe 135a to a plurality of

control valves

137, 138, 139 and 140 which are arranged to control 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. The

control valves

137, 138, 139 and 140 are manually actuated valves controlled by operating

handles

141, 142, 143 and 144 respectively. The

valves

137, 138, 139 and 140 are identical in construction consequently only one of these valves has been illustrated in detail in Fig. 6. This valve will be hereinafter described.

Fluid under pressure from the pipe 135 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 an automatically controlled oscillating or reciprocatory movement of the grinding wheel 58. The solenoid valve 145 is a piston type valve having a slidably mounted valve member 146 having a plurality of

valve pistons

147, 148, 149 and 150 formed integrally therewith. The Valve member 146 is normally held in a central position by a pair of balanced compression springs 151 and 152. A pair of solenoids S2 and S1 are provided to shift the valve member 146 in either direction. As positioned in Fig. 7 fluid under pressure from the pipe 135 passes into a valve chamber 155 formed between the

valve pistons

148 and 149 respectively. When the solenoid S2 is energized, the valve member 146 moves toward the right so that fluid under pressure from the pipe 135 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 15 in a counter-clockwise direction, thereby imparting a swinging movement of the grinding wheel 58 also in a counter-clockwise direction. During this movement fluid within the cylinder chamber 124 may exhaust through the pipe 125 into a valve chamber 156 formed between them and passes out through a pipe 157, through a throttle valve 158 and through an exhaust pipe 159 into the reservoir 130.

Similarly when the solenoid S1 is energized, the valve member 146 moves towards the left (Fig. 7) so that fluid under pressure from the 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 platen 45 together with the grinding wheel 58 in a clockwise direction.

' During this movement fluid within the cylinder chamber 123 exhausts through the pipe 122 into a valve chamber 160 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 into the reservoir 130. It will be readily apparent that 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 and thereby controls the rate of oscillation or reciprocation of the grinding wheel 58.

It is desirable that the reciprocating movement of the grinding wheel continue automatically through a predetermined stroke. The platen 45 is provided with an actuating arm 165 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 170 and a stop switch 171 is provided to stop and start the lateral oscillation or reciprocating movement of the grinding wheel 58. The limit switch LS1 is a normally closed limit switch and the limit switch LS2 is normally opened. The limit switches LS1 and LS2 are connected through a relay switch 174 with the solenoids S1 and S2 of the control valve 145. When the start switch 170 is closed current passes through the contactor 172 of the relay switch 17 4 to energize the solenoid S2 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 counterclockwise swinging movement of the platen 45 and the grinding wheel 58. This counter-clockwise movement of the grinding wheel 58 continues until the arm 165 engages the actuating roller 167 of the limit switch LS2 which serves to make a circuit thereby energizing the relay switch 174 to open the contactor 172 and to close the contactor 173. Opening the contactor 172 serves to deenergize the solenoid S2 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 174 so as to energize the solenoid S1 thereby shifting the valve member 146 toward the left so as to admit fluid under pressure to the cylinder chamber 124 to start a swinging movement of the platen 45 and the grinding wheel 58 in a clockwise direction. It will be readily apparent from the foregoing disclosure that 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 174 is opened manually to render the circuit inoperative thereby stopping the oscillation of the platen 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

control valves

137, 138, 139 and 140 are identical in construction. These valves are arranged side by side and fastened together by a plurality of

tie rods

180, 181, 182 and 183. The valve assembly is fixedly mounted on a vertical plate 184 supported at the operators station 42.

Fluid under pressure from the pipe 135a passes through a longitudinal passage 185 which extends through all four of the valves. Similarly an exhaust passage 186 extends through all of the

valves

137, 138, 139 and 140 and is connected to an exhaust pipe 187 to return exhausting fluid to the fluid reservoir 130.

As above stated the

valves

137, 138, 139 and 140 are identical in construction consequently only the valve 140 has been illustrated and will be described in detail. These valves are piston type valves comprising valve stems 190 having valve pistons 191, 192 and 193 formed integrally therewith. A compression spring 194 is provided, nor mally to hold the valve in a central or neutral position as indicated in Fig. 6. The control 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. The control lever 144 is connected by a stud 199 with the upper end of the valve stem 190.

When the control lever 144 is moved toward the operator, that is, toward the right (Fig. 6), the valve stem 190 is depressed so that fluid under pressure from the passage 185 enters a valve chamber 200 formed between the valve pistons 192 and 193 and passes out through a passage 201, through the pipe 111 into the cylinder chamber 112 to cause a downward movement of the piston 106 thereby rocking the swing frame grinder unit 56 in a clockwise direction about its longitudinal axis. During this movement fluid Within the 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 203, through the longitudinal passage 186 and through the exhaust pipe 187 into the reservoir 130.

Similarly as the control lever 144 is moved away from the operator, that is, toward the left (Fig. 6) an upward movement is imparted to the valve stem 190 so that fluid under pressure entering the valve chamber 200 passes through the pipe 114 to rock the swing frame grinder unit 56 in a counter-clockwise direction about its longitudinal axis. This valve as above stated serves to position the grinding wheel 58 for grinding adjacent to either one corner or the other corner thereof. It will be readily apparent from the foregoing disclosure that the valve stem 190 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 190 into the central or neutral position as indicated in Fig. 6.

When the control lever 143 is moved toward the operator the valve 139 is shifted so that fluid under pressure passes through the pipe to cause a downward movement of the piston 91 to rock the swing frame grinder unit in a counterclockwise direction about the axis of the stud 53. When the control lever 143 is moved away from the operator, fluid under pressure 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.

Similarly when the control lever 142 is moved toward the operator fluid under pressure 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 counter-clockwise direction. When the control lever 142 is moved away from the operator fluid under pressure is passed through the pipe 85 to cause a swinging movement of the column 50 in a clockwise direction about the axis of the rock shaft 49.

When the control lever 141 is moved toward the operator fluid pressure is passed through a pipe 210 to the fluid motor 23 to cause the carriage 12 to traverse in one direction. During this movement fluid exhausts from the other side of the fluid motor 23 through a pipe 211. Similarly when the control lever 141 is moved away from the operator fluid under pressure is passed through the pipe 211 to the fluid motor 23 to rotate the drive shaft thereof in the reverse direction thereby imparting a lon gitudinal traverse movement of the carriage 12 in the reverse direction.

The operation of the improved snagging grinder will be readily apparent from the foregoing disclosure the controls for the machine are arranged so that the operation thereof may assimilate the operation now obtained manually through manually operated swing frame grinding machines. A work piece such as a billet 70 is positioned on the work support 71. The push button 175 is actuated to start the fluid pump motor 132. The switch 177 is actuated to start the wheel driving motor 62 to rotate the grinding wheel 58.

In a snagging operation of this type it is sometimes desirable to use the peripheral face of the wheel and other times it may be desirable to utilize a corner portion at either side of the peripheral face to perform the grinding operation. A control lever 144 is provided to control the admission of fluid under pressure to the cylinder so as to rock the swing frame grinder unit 56 about its longitudinal axis so that the grinding wheel may be positioned so that the entire peripheral face may be used or either corner portion thereof, as desired.

The control lever 141 is then manipulated to traverse the carriage 12 longitudinally in either direction to position the grinding wheel 58 in position adjacent to the portion of the billet surface to be ground. The push button 170 is then actuated to start an oscillating or reciprocating movement of the grinding wheel through a relatively short stroke, such as for example, 3 feet.

The control lever 142 is manipulated to cause a swinging movement of the column 50 to facilitate a transverse movement of the grinding wheel to position it relative to the surface to be ground.

The control lever 143 is then manipulated to pass fluid under pressure to the cylinder chamber 101 to cause the swing frame grinder unit 56 to swing about the axis of the rock shaft 53 yieldingly to maintain the grinding wheel 58 in operative engagement with the surface of the work piece 70 as the grinding wheel 58 oscillates or reciprocates longitudinally. While cylinder and piston 116 cause an oscillation 'of the platen 45, the column 50, the swing frame grinder unit 56, due to the yielding action of the piston 91, the grinding wheel 58 will be caused to reciprocate longitudinally in a substantially rectilinear path instead of an arcuate path. After a portion of the work has been ground, the control lever 142 is actuated to cause a swinging movement of the column 50 to position the grinding wheel transversely for grinding other portions on the surface of the work piece 70. After the portion of the work piece 70 has been ground to the desired extent, the control lever 141 may be actuated to traverse carriage 12 longitudinally to bring the grinding wheel 58 in operative relation with a different-portion of the Work piece to be ground. 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 billets may be ground. The first work piece is ground to the. desired extent, after which the carriage 12 may be traversed longitudinally to position 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 workpiece.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved.v As many possible embodiments may be made of the above invention and as many changes might be made in the embodiments above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A snagging grinder having a pair of spaced parallel guideways, a longitudinally movable carriage thereon, a platen pivotally mounted on said carriage arranged to swing about an axis normal to said ways, a vertically arranged column pivotally supported on said platen, a swing frame pivotally supported 'on the lower end of the said column, a motor driven grinding wheel on said frame, means including a fluid motor on said carriage operatively connected to traverse said carriage longitudinally in either direction to facilitate positioning the grinding wheel relative to the work piece being ground, and a fluid motor operatively connected between the carriage and platen to facilitate rocking said platen and column so as to impart a reciprocating movement to said grinding wheel.'

2. A snagging grinder having a pair of spaced parallel guideways, a longitudinally movable carriage, a vertically arranged depending column pivotally mounted thereon, said column being arranged to swing about an axis parallel to and an axis parallel to said ways, a swing frame pivotally mounted at the lower end of said column, a motor driven grinding wheel on said frame, means including a fluid motor on said carriage operatively connected to traverse the carriage longitudinally in either direction, means including a fluid motor operatively connected to swing said column about an axis parallel to said ways so as to impart a transverse movement to said swing frame, means including a fluid motor operatively connected to swing said swing frame relative to said column so as to maintain the grinding wheel in operative engagement with the work piece being ground at the desired pressure, and means including a fluid motor operatively connected to oscillate said column and swing frame about an axis normal to said ways in a direction parallel to the longitudinal movement of said carriage so as to impart a longitudinal reciprocatory movement to the grindling wheel in a direction parallel to the guideways.

3. A snagging grinder having a pair of spaced parallel guideways, a longitudinally movable carriage thereon, a platen pivotally mounted on the carriage arranged to swing about an axis normal to said ways, a vertically arranged column pivotally supported on said platen, said column being arranged to swing about an axis parallel to said ways, a swing frame pivotally supported at the lower end of said column, said frame being arranged to swing about an axis parallel to said ways, a motor driven grinding wheel on said frame, means including a fluid motor on said carriage to traverse said carriage longitudinaly in either direction to facilitate positioning the grinding wheel relative to the work piece to be ground, and an independent fluid motor operatively connected between the carriage and the platen to facilitate rocking said platen and the column so as to impart a longitudinal reciprocatory movement to said grinding wheel relative to the work piece to be ground.

4. Avsnagging grinder having a pair of spaced parallel guideways, a longitudinally movable carriage thereon, means including a fluid motor on said carriage operatively connected to traverse said carriage longitudinally in either direction, a platen pivotally mounted on said carriage arranged to swing about an axis normal to said guideways, a vertically arranged depending column pivotally supported on the underside of the said platen and arranged to swing about an axis parallel to said guideways, means including a fluid motor operatively connected between said platen and column to facilitate swinging said column transversely, a bracket pivotally supported on the lower end of said column and arranged to swing about an axis parallel to said guideways, a swing frame rotatably supported on said bracket, said frame being arranged to be rotatably adjusted about its longitudinal axis, a motor driven grinding wheel on said frame, a fluid motor operatively connected to rotate said frame about its longitudinal axis to facilitate positioning the operative face of the grinding wheel, and means including a fluid motor operatively connected between the carriage and platen to impart an oscillating movement to said platen so as to cause a reciprocating movement of the grinding wheel relative to the work being ground.

References Cited in the file of this patent UNITED STATES PATENTS 1,256,072 Stevenson Feb. 12, 1918 1,488,711 Rohlfing Apr. 1, 1924 2,308,842 Wilson Jan. 19, 1943 2,627,704 Whitehouse Feb. 10, 1953 FOREIGN PATENTS 612,690 France Aug. 4, 1926 719,575 France Nov. 23, 1931