US1938760A - Grinding machine - Google Patents

Description

Dec. 12, 1933. FR|T$H| 1,938,760

GRINDING MACHINE Filed Aug. 1'7, 1932 4 Sheets-Sheet l HIH I H 57 Gnome/ 3 Dec. 12, 1933. H. FRITSCHl GRINDING MACHINE Filed Aug. 17, 1932 4 heets-Sheet 2 Dec. 12, 1933.

H. FRITSCHI GRINDING MACHINE Filed Aug. l7, 1932 4 Sheets-Sheet 3 llllllllllllllllHHi m. 12, 1933. v H. mscm 1,938,760

GRINDING MACHINE Filed Aug. 17, 1932 4 Sheets-Sheet 4 WWW Patented Dec. 12, 1933 UNITED STATES PATENT oFFlcE cinnati Grinders Incorporated, Cincinnati,

Ohio, a corporation of Ohio- Application August 17, 1932. Serial No. 629,184i

19 Claims.

This invention relates to improvements in grinding machines and more'especially to improvements in cross feed mechanism for effecting the movement of the grinding wheel carriage.

An object of the invention is the provision of an improved hydraulically operated cross feed mechanism.

Another object of the invention is the provision of a grinding machine including an hydraulically actuated cross feed mechanism that may be employed in the performance of normal traverse grinding operation or for the performance of what is known as plunge cutting operations.

A further object of the invention is the provision of improved cross feed mechanism of the pick feed type and including an improved structure for varying the amount of incremental feed.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification considered in conjunction With the accompanying drawings, forming a part thereof, and, it is to be understood that any modifications may be made in the exact structural details there shown and described within'the scope of the appended claims, without departing from or exceeding the spirit of the invention.

In the drawings: a

Figure l is a front elevational view of a grinding machine embodying the improvements of this invention.

Figure 2 is a fragmentary sectional'view taken on line 2-2 of Figure 1. v

Figure 3 is a fragmentary transverse sectional view through the machine as seen particularly from line 3-3 on Figure 1.

Figure 4 is a view partly in section and partly in elevation as seen from line 4-4 on Figure 3.

Figure 5 is a fragmentary sectional view taken on line 5--5 of Figure 1. I

Figure 6 is a sectional view taken on line 66 of Figure 2.

Figure 7 is a sectional view taken on line '7---'7 of Figure 6.

til

Figure 8 is a diagrammatic view illustrating the hydraulic circuits involved in this invention.

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

A machine embodying this invention may comprise a bed 10 of the usual construction as used with center type grinding machines and having formed ,on its upper surface suitable guideways 11 and 12 receiving guide tongues depending from a work supporting table 13 mounted thereon for movement relative thereto. The table 13 has ad-- justably secured to it, as is usual practice, a self-- contained head stock 14 and a tail stock 15 between which work pieces to be operated upon are disposed.

The table 13 and parts carried thereby may be translated relative to the bed by any suitable or desirable 'means, such for example, as that shown diagrammatically in Figure 8. The means shown in Figure 8 for effecting the movement of the table 13 comprises a cylinder 16 carried by the bed 10 and enclosing a double acting piston 17; Projecting from the piston 17 is a piston rod 18 having its forward end secured to a bracket 19 depending from the table 13 interiorly of the bed. In order to operate the piston 17 there is provided a pump 20 having an inlet side to which is connected a suction pipe 21 terminating in a suitable sump or-tank 22 contain- .ing an hydraulic medium, preferably oil, utilized for the operation of the piston 17. Connected with the discharge side of the pump 20 is a pipe or conduit 23 terminating on its upper end with a valve casing 24, shown structurally in Figure '7. Enclosed within the valve casing 24 is a piston type slidable valve 25 having formed thereon collars 26 and 27 between which is formed a cannelure 28. The cannelure 28 is adapted to connect the discharge from the conduit or line 23 with one or the other of conduits 29 and 30 respectively terminating at the left and right hand ends of the cylinder 16, as seen in Figure 8. The connection of the line 23 with one or the other of the conduits 29 and 30 by the valve 25 automatically connects the remaining line through the valve with one or the other of branch exhaust lines 31 and 32, which are connected by a common return or exhaust line 33 that terminates in the sump 22. c

The valve 25 is adapted to be reversed at each end of the work table strokefor thereby reversing the movement of the table. For this purpose the table has secured to its forward surface a pair of reversing dogs 11S and 119 adapted to engage with a projection 11'? extending from the rear surface of a reversing lever 116, as is usual practice. This lever 116 is keyed or otherwise secured to a shaft 120 rotatably journaled in a suitable bearing formed in a reversing plate 126 secured to the forward face of the bed 10 and the plate 126 carries and encloses the reversing mechanism including among other elements the reversing valve 25 and the cross feed piston 69 and parts actuated thereby. Interiorly of the plate 126 the shaft 120 has secured to its other end a lever 121 which may be directly connected to the reversing valve stem, not shown in the drawings as this may be of any usual construction. Therefore, engagement of the reversing lever abutment 117 with either of the reversing dogs 118 or 1 19 will effect oscillation of the lever 116 and initiate movement of the reversing valve 25.

In order to complete the movement of the reversing valve 25, and as is usual practice, there is provided a load and fire mechanism. This load and fire mechanism comprises a valve stem 128 which passes through a bore formed centrally through the valve 25 and to the stem 128 may be directly connected, as above described, the free end of the lever 121. The stem 128 is further provided with a collar 129 in which is formed notches 130 and 131 each having the walls inclined to act as cam surfaces. (lo-operating with the cam-like walls of the notches 130 and 131 is a yieldably actuated load and fire mechanism comprising a member 132 having a head whose surfaces are inclined to engage the cam faces of notches 130 and 131. The member 132 has a counterbore therein receiving a spring 133 which abuts on one end with thebase of the counterbore and on the other end with a plug 134 that closes the passage 135 through which the projection on the reversing lever for oscillating same, which in turn oscillates the lever 121 for shifting the valve stem 128. The movement of the valve stem 128 causes the notches 130 and 131 to be moved relative to the member 132 and due to the inclined walls of the notches causes said member 132 to ride up the side of the notch in which it is positioned. By the time the member 132 reaches the top of the ridge between the notches, the lost motion between the valve 25 and the collar 129 or shoulder 136 is taken up and as soon as the member 132 passes said ridge the spring, which was compressed during the upward movement of the member 132, expands or fires the valve stem 128 to the other end of its movement carrying with it the valve 25 and thereby reversing the connection through said valve.

The bed 10 has extending from its rear side an extension 34 on the upper surface of which is formed guideways 35 for a slide or carriage 36. The carriage 36 rotatably supports a spindle 3'7 to the end of which is secured a grinding wheel 38 for operation on the work carried by the head and tail stocks. The grinding wheel 38 is suitably enclosed within a guard 39 that confines the coolant usual with grinding machines.

The carriage 36 is adapted to be actuated relative to the bed extension 34 toward the work to effect a stock-removal therefrom and from the work to permit a replacement of the work. For this purpose the carriage 36 has secured to it or'formed integral therewith and depending interiorly of the bed extension 34 a bracket 40 having keyed or pinned therein a nut 41. The nut 41 is in threaded engagement with a cross feed screw 42 and the nut has extending from it a cylindrical skirt or guard 43 adapted toprotect the threads of the screw from dirt and other foreign substances. The screw 42 is adapted to be both axially shifted and rotatably actuated for effecting the movement of the carriage, the former movement being employed for rapidly adjusting the position to the carriage and grinding wheel and the latter for finely positioning said carriage and for incrementally feeding the work and wheel relative to one another.

To efiect the rapid movement of the carriage 36 the screw has secured to it near its outer end a piston 44 enclosed within a cylinder 45 which has its ends closed as by means of heads 46 and 47. These heads 46 and 4''! have extending through them the screw 42 for forming bearings for said screw. Respectively secured to the heads 46 and 47 are pipes 48 and 49 which convey hydraulic medium to opposite sides of the piston 44 for effecting its movement. These pipes are connected with a suitable source of hydraulic pressure and with the sump, which will take place through a reversing valve similar to the valve 25.

The cylinder 45 and parts associated therewith are secured to an extension 50 projecting rearwardly from a plate or housing 51 secured to the forward face of the bed 10. Enclosed within the housing 51 and journaled in the extension 50 is a gear 52 having a bore centrally thereof in which is formed a plurality of keyways receiving the splined portion 53 of the screw 42. By this construction it will be noted that the screw may be axially shifted without breaking the driving connection between the splined portion 53 and the hub of the gear 52. Meshing with the gear 52 is a pinion 54 formed integral with or secured to a shaft 55 rotatably journaled insuitable antifriction bearings carried by the housing 51 and housing cover plate 56. The shaft 55 has loosely journaled on it'a hand wheel 5'? carrying a slidable handle or plunger 58. The plunger 58 has interiorly thereof a spring 59 tending to yieldably shift a projecting pin or tongue 60 thereof into any oneof a plurality of sockets 61 formed around the ratchet wheel 62. The ratchet 62 is provided exteriorly with ratchet teeth 63 and interiorly with gear'teeth 64. The gear teeth 64 mesh with the teeth of a gear 65 rotatably journaled on a stud 66carried by a plate member 67 keyed or otherwise secured to the shaft 55. The gear 65 in turn meshes with a pinion 68 formed integral with the hand wheel 57 or at least secured to said hand wheel 57 for movement with said hand wheel.

With the parts in the position shown in Figure 3, the rotation of the hand wheel 57, by means of the plunger handle 58, and the interengagement of the pin 60 and ratchet wheel 62, effects a unitary rotation of the parts and the shaft 55 at the same rate. r The rotation of the shaft 55 rotates the pinion 54 and gear 52 which through its connection with the screw 42 effects the rotation thereof and consequent adjustment of the slide. In order to rotate the screw 42 at a very slow rate of speed, as when adjusting the parts to take up for wheel wear, which is in the nature of a fraction of a thousandth of an inch, the plunger handle 58 is withdrawn against the spring 59 to withdraw the pin 60 from its socket 61 whereupon the hand wheel is again rotated, but this time only turns the pinion 63 associated therewith which through the planetary gear 65 and internal gear 64 rotates the plate 67 and very slowly rotates the screw. By this construction the screw is rotated but a fraction of a revolution for each complete revolution of the hand wheel 57 and thereby incrementally adjusts the position of the parts while with the plunger pin 60 in engagement with one of its sockets so that the parts are given a unitary movement, the adjusting screw is given a complete revolution for each rotation of the hand wheel.

In the normal operation of the machine these parts are automatically operated as by means of a pawl mechanism operating on the teeth 63 of the ratchet 62. This pawl mechanism comprises a piston 69 enclosed within a cylinder '70 formed, for example as shown in Figure '7, integral with the valve casing 24. The piston 69 has projecting from its ends reduced nipples 71 and '72 adapted to engage with plugs '73 and 74 carried by the ends of the cylinder '70. The nipples '71 and '72 at all timesspace the end of the piston 69 from the plugs '73 and '74 for at all times maintaining a chamber at the ends of the cylinder in communication with the pressure and exhaust conduits utilized for operating said piston. As shown in Figure 8, the right and left hand ends of the cylinder '70 are respectively connected by means of conduits '75 and '76 with the conduits 29 and 30. The piston 69 is provided on one side with rack teeth '77 meshing with the teeth '78 formed on the lower end of a vertically oscillatable shaft '79. The vertically oscillatable shaft 79 is mounted for movement in the block 79a in which is formed the valve casing 24 and cylinder '70 and projects above the upper surface of saidblock.

A heart-shaped cam member 80 is secured to or formed integral with the member '79 above the block and is adapted to engage a roller 81 rotatably carried by the under surface of a lever 82.

The lever 82 is pivoted at 83 to the upper surface of the block 79a and extends forwardly through an opening 84 formed in the housing cover plate 56, as well as through an opening 85 formed in the adjacent side of a substantially cylindrical housing 86. The free end 8'7 of the lever 82 is disposed interiorly of the housing 86 and is adapted when oscillated to contact with the end of a plunger 88 for shifting same. This plunger 88, see Figure 4, is provided with an enlarged portion 89 at its rear end followed by a reduced portion 90 to which is connected a head 91. The head 91 is provided with a longitudinal slot 92 in which is disposed a pawl 93 having its rear end pivoted as at 94. The free end of the pawl 93 is provided with a nose or point 95 which is adapted to engage behind the ratchet teeth 63. The pawl 93 is further provided with a socket 96 in which is a spring 97 abutting on opposite ends with the base of the socket 96 and with the base of the notch 92.

The plunger 88 and parts carried thereby are received in a sleeve 98 axially adjustable relative to the housing 86. The sleeve is provided with a bore 99 of a diameter equal tothe enlarged end portion 89 of the plunger and provides a guide for the movement of the plunger 88. Surrounding the reduced portion 90 of the plunger is a spring 100 which abuts on one end with the shoulder formed'by the enlarged portion 89 of the plunger and on the other end with a radial flange 100a forming the base of the bore 99 and the base of a counterbore on the other side thereof. The spring 100 yieldably urges the plunger 88 to the left, as seen in Figure 4, and thereby maintains contact between the end of the plunger head 91 and the radial flange 100a forming the base of a counterbore in the sleevein which said head is disposed.

For each axial reciprocation of the plunger 88 the pawl 93 is adapted to engage one or more of the ratchet teeth 63. For the purpose of 'determining the amount or number of ratchet teeth to be engaged. for each reciprocation of the plunger 88, the sleeve 98 is axially adjustable and adapted to be held in its adjusted positions. For this purpose the upper surface of the sleeve at one end thereof is provided with rack teeth 101 adapted to engage with the teeth on rack pinion 102 keyed or otherwise secured to a shaft 103 for movement therewith. The under surface of the sleeve is provided with notches 104 co-operating with the spring pressed detent 105. This detent is counterbored to receive the spring 106 which abuts on opposite ends with the base of the counterbore and a plug 107 which closes the passage 108 in which the spring is disposed. The sleeve 98 is formed at the end of the counterbore in which the plunger head 91 is disposed with a bevelled or cammed face 109 co-operating with the inclined or cammed surface 110 formed on the pawl 93 adjacent its nose 95 for actuating the pawl in a direction against the yielding resistance of the spring 96.

From the foregoing it will be noted that the lever 82 has a definite path of oscillation imparted thereto by the cam 80 and that the free end of the plunger enlarged portion 89 is variably spaced relative to the path of oscillation of the free end 87 of the lever 82. From this it will be seen that the plunger 88 is shifted relative to its sleeve 98 variable amounts depending upon the axial position thereof relative to the housing 86 for thereby variably effecting incremental feeding movements of the grinding wheel and its car- 'riage toward the work.

In order to rotate the shaft 103 and thereby the pinion for shifting the sleeve 98, the shaft 103 is journaled in the housing 86 projecting beyond said housing toward the operator. The projecting end of the shaft 103 has secured to it a lever 111 carrying a locking pawl 112 adapted to enter suitable notches 113 formed on a plate carried by the housing 86. The pawl 112 is yieldably urged toward its locking plate by means of a spring 114 which surrounds the stem of the pawl. The pawl stem has screwed to its free end a knob 115 whereby the pawl is actuated against the resistance of the spring 114 for releasing the lock to permit further adjustment of the handle 111.

It will be noted from Figure 8 that the same valve 25 that is utilized for effecting the reverse coupling of the hydraulic medium with the cylinder 16 is utilized for effecting the reverse operation of the piston 69. From this it will be seen that for each reversal of the table movement the piston 69 is operated for effecting an incremental feed of the grinding wheel toward the work. The reverse shifting of the valve 25 is effected by the means described above through the operation of the reversing dogs 118 and 119 acting on the lever 116. The above described structure is utilized during normal traverse grinding, that is, when the work table is translated to traverse the work across the grinding wheel when it is desired that the table tarry slightly before reversal. When, however, it is desired to perform a plunge cutting operation, that is, with substantially no table traverse except a slight axial movement between the work and wheel to break up grinding linesQit is desired that a substantially instantaneous reverse of the table be had and within an extremely short table stroke. For this reason, and as shown in Figure '7, the lever 121 is pivoted at 122 to one end of a link 123 which has its other end pivoted 125. This lever 125 is in turn pivoted at its upper 'at 124 to a point intermediate a depending lever end to the interior'of the reverse" plate or housing 126 and has its lower end pivoted at 127 to the stem of the reversing valvef25.

Due to the particular lever and linkage arrangement, namely the lever 121, link 123 and lever 125, the valve stem 128 has imparted to it considerably more movement than the lever 121. By this construction the valve 25 may be operated from its reverse positions with a very short movement of the lever 121 and consequently the lever 116. In other words, with this construction the table 13 may be reciprocated through an extremely short stroke and therefore at a comparatively rapid rate for breaking up grinding lines on the work, as when performing plunge cutting operations. By this construction also and since the reversing valve 25 effects the incremental infeed of the grinding wheel for each reversal of the valve the grinding wheel is fed into the work, thereby expeditiously performing plunge cutting operations on work pieces within a minimum of time and without the use of special mechanism as was the case with grinding machines of the past that were adapted to per- =form both traverse grinding and plunge cutting operations on the same machine.

What is claimed is:

1. In a cross feed mechanism for use with grinding machines the combination with a bed, of

a grinding wheel carriage mounted thereon for movement relativethereto, an adjusting screw operatively connected with the carriage, and a ratchet and pawl mechanism for incrementally rotating the screw and thereby incrementally feeding the carriage relative to the bed including a reciprocable plunger having secured thereto the pawl, a sleeve enclosing the plunger, a spring yieldably shifting the plunger in one direction relative to the sleeve, means associated with the plunger and sleeve for limiting the movement of the plunger under influence of the spring, and hydraulically actuated means for shifting the plunger against the resistance of the spring.

2. In a cross feed mechanism for use with grinding machines the combination with a bed, of a grinding wheel carriage mounted thereon for movement relative thereto, an adjusting screw operatively connected with the carriage, and a ratchet and pawl mechanism for incrementally rotating the screw and thereby incrementally feeding the carriage relative to the bed including a reciprocable plunger having secured thereto the pawl, a sleeve enclosing the plunger, a spring yieldably shifting the plunger in one direction relative to the sleeve, means associated with the plunger and sleeve for limiting the movement of the plunger under influence of the spring, an oscillatable lever adapted to have its free end engaging with the plunger to shift same against the resistance of the spring, and hydraulic means for effecting the oscillation of the lever.

3. In a cross feed mechanism for use with grinding machines the combination with a bed, of a grinding wheel carriage mounted thereon for 'movement relative thereto, an adjusting screw operatively connected with the carriage, and a ratchet and pawl mechanism for incrementally rotating the screw and thereby incrementally feeding the carriage relative to the bed including a reciprocable plunger having secured thereto the pawl, a sleeve enclosing the plunger, a spring yieldably shifting the plunger in one direction relative to the sleeve, means associated with the plunger and sleeve for limiting the movement of the plunger under influence of the spring, an oscillatable lever adapted to have its free end engaging with the plunger to shift same against the resistance of the spring, an oscillatable shaft, a cam on said shaft, an operative coupling be-- tween the cam and lever whereby oscillations of the cam effect oscillations of the lever, and an hydraulically actuated piston for oscillating the shaft.

4. In a cross feed mechanism for grinding machines the combination with a bed, a grinding wheel carriage mounted thereon for movement relative thereto, of a screw operatively associated with the carriage, a ratchet and pawl mechanism for effecting incremental rotation of the screw including a reciprocable plunger to which is pivotally secured the pawl, yieldable means for shifting the plunger in one direction, power means for shifting the plunger in the other. direction, and means for variably positioning the plunger relative to the power shifting means whereby to vary the stroke of the plunger and consequent feeding of the screw per reciprocation of the plunger, comprising a sleeve enclosing the plunger, a housing supporting the sleeve, co-opcrating means on the sleeve and plunger for limiting the movement of the plunger under the influence of the yielding means, and means shifting the sleeve relative to its housing.

5. In a cross feed mechanism for grinding machines the combination with a bed and a grinding wheel carriage mounted thereon for movement relative thereto, of a screw operatively associated with the carriage, a ratchet and pawl mechanism for effecting incremental rotation of the screw including a reciprocable plunger to which is pivotally secured the pawl, yieldable means for shifting the plunger in one direction, power means for shifting the plunger in the other direction, and means for variably positioning the plunger relative to the power shifting means whereby to vary the stroke of the plunger and consequent feeding of the screw per reciprocation of the plunger, comprising a sleeve enclosing the plunger, a housing supporting the sleeve, co-operating means on 120 the sleeve and plunger for limiting the movement of the plunger under the influence of the yielding means, said sleeve having a rack secured thereto, a pinion engaging the rack, and a spring detent for holding the sleeve in its relative posi- 125 tions relative to the housing.

6. In a cross feed mechanism for use with grinding machines and the likethe combination with a ratchet and pawl mechanism for effecting said cross feed, of a'reciprocable plunger, a head 130 on said plunger to which the pawl is pivotally secured, a sleeve enclosing the plunger and having a radialflange intermediate its ends, yielding means for shifting the plunger relative to the sleeve and engaging the plunger head with the 135 radial flange, the sleeve having a cam face formed at one end thereof co-operating with a cam on the pawl for disengaging the pawl from the ratchet when in its normal retracted position under influence of the spring, and power means 140 for shifting the plunger relative to the sleeve to disengage the pawl cam and sleeve cam and effect "engagement between the pawl and ratchet teeth.

means for shifting the plunger relative to the sleeve and engaging the plunger head with the radial flange, the sleeve having a cam face formed at one end thereof co-operating with a cam on the pawl for disengaging the pawl from the ratchet when in its normal retracted position under influence of the spring, power means for shifting the plunger relative to the sleeve to disengage the pawl cam and sleeve cam and effect engagement between the pawl and ratchet teeth, a housing enclosing the sleeve, means for shifting the sleeve relative to the housing to thereby vary the effect of the power operating means and vary the amount of rotation of the ratchet per stroke of the plunger, and means for locking the sleeve in its adjusted position relative to the housing.

8. In a grinding machine of the class described the combination of a bed, a work supporting table mounted thereon for translation relative thereto, a grinding wheel carriage mounted on the bed for incremental movement toward the work supporting table, hydraulic means for effecting a reverse translation of the table, a ratchet and pawl mechanism for effecting the incremental feed of the grinding wheel carriage and including a reciprocable plunger carrying the pawl, 'a reversely oscillatable cam for effecting the shifting of the plunger on each oscillation thereof, an hydraulically actuated piston for oscillating the cam, and a reversing valve operable by the table at each end of its translatory stroke for reversing the movement of the table and effecting the oscillation of the cam.

9. In a grinding machine of the class described the combination of a bed, a work supporting table mounted thereon for translation relative thereto, a grinding wheel carriage mounted on the bed for incremental movement toward the work supporting table, hydraulic means for effecting a reverse translation of the table, a ratchet and pawl mechanism for effecting the incremental feed of the grinding wheel carriage and including a reciprocable plunger carrying the pawl, a reversely oscillatable cam for effecting the shifting of the plunger on each oscillation thereof, an hydraulically actuated piston for oscillating the cam, a

reversing valve operable by the table at each end of its translatory stroke for reversing the movement of the table and effecting the oscillation of the cam, and yielding means for retracting the plunger.

10. In a grinding machine of the class described the combination of a bed, a work supporting table mounted thereon for translation relative thereto, a grinding wheel carriage mounted on the bed for incremental movement toward the work supporting table, hydraulic means for effecting a reverse translation of the table, a ratchet and pawl mechanism for effecting the incremental feed of the grinding wheel carriage and including a reciprocable plunger carrying the pawl, an hydraulically actuated piston for shifting the plunger, a reversing valve operable by the table at each end of its translatory stroke for reversing the movement of the table and the operation of the plunger in one direction, yielding means for retracting the plunger, and cam means for disengaging the ratchet and pawl when the plunger is in a retracted position.

11. In a mechanism of the class described the combination with a bed, of a work supporting table mounted thereon for translation relative thereto, a grinding wheel carriage mounted on the bed for movement toward the work supporting table, hydraulic means for effecting the translation of the table and feed of the grinding wheel carriage, a reversing valve for reversing the direction of movement of the table at each end of its stroke in a given direction, a reversing lever operable by the table for effecting the reversing of the reverse valve and means between the reversing lever and reversing valve whereby the movement impartcdto the reversing lever is amplified for shifting the valve and whereby the amount of table movement per reversal is reduced to a minimum.

12. In a mechanism of the class described the combination with a bed, of a work supporting table mounted thereon for translation relative thereto, a grinding wheel carriage mounted on the bed for movement toward the work supporting table, hydraulic means for effecting the translation of the table and feed of the grinding wheel carriage, a reversing valve for reversing the direction of movement of the table at each end of its stroke in a given direction, a reversing lever operable by the table for effecting the reversing of the reverse valve, means between the reversing lever and reversing valve whereby the movement imparted to the reversing lever is amplified for shifting the valve and whereby the amount of table movement per reversal is reduced to a minimum, and connections between the hydraulic cross feed mechanism and the table translating 1';

mechanism whereby the grinding wheel carriage is incrementally fed for each reversal of table translation.

13. In a mechanism of the class described the combination with a bed, of a work supporting '1 table mounted thereon for translation relative thereto, a grinding wheel carriage mounted on the bed for movement toward the work supporting table, hydraulic means for effecting the translation of the table and feed of the grinding wheel carriage, a reversing valve for reversing the direction of movement of the table at each end of its stroke in a given direction, a reversing lever operable by the table for efiecting the reversing of the reverse valve, means between the reversing lever and reversing valve whereby the movement imparted to the reversing lever is amplified for shifting the valve and whereby the amount of table movement per reversal is reduced to a minimum, connections between the hydraulic cross feed mechanism and the table translating mechanism whereby the grinding wheel carirage is incrementally fed for each reversal of table translation, and a common pressure source for actuating the table translating mechanism and grinding wheel carriage feeding mechanism. 7

14. In a grinding machine of the class described the combination with a bed, a work supporting table mounted thereon for translation relative thereto, and a grinding wheel carriage mounted on the bed for movement toward the work supporting table, of cross feed mechanism for effecting the incremental movement of the carriage toward the table including a ratchet and pawl mechanism, a plunger to which the pawl is pivotally secured, a reversely oscillatable cam, and a vpivotally mounted lever having contact with the cam intermediate its ends and whereby the said lever is oscillated about its pivotal mounting, said lever having its free end in line with the plunger for engagement therewith and effecting a movement thereof upon oscillation of the lever.

15. In a grinding machine of the class de-- scribed the combination with a bed, a work supthe plunger.

porting table mountedthereon for translation relative thereto, and a grinding wheel carriage carried by the bed for movement toward the work supporting table, of a cross feed mechanism for effecting the movement/0f the carriage including a ratchet and pawl, a plunger pivotally carrying the pawl, a reversely oscillatable cam, a lever pivotally mounted at one end and engaging the plunger at the other end and contacting with the cam intermediate its ends, and means for effecting the reverse oscillations of the cam for oscillating the lever in one direction and correspondingly reciprocating the plunger.

16. In a grinding machine of the class described the combination with a bed, a work supporting table mounted thereon for translation relative thereto, and a grinding wheel carriage carried by the bed for movement toward the work supporting table, of a cross feed mechanism for efiecting the movement of the carriage including a ratchet and pawl, a plunger pivotally carrying the pawl, a reversely oscillatable cam, a lever pivotally mounted at one end and engaging the plunger at the other end and contacting with the cam intermediate its ends, means for efiecting the reverse oscillations of the cam for oscillating the lever in one direction and correspondingly reciprocating the plunger, and yielding means for shifting the plunger in the opposite direction and returning the lever to its normal position.

17. In a grinding machine of the class described the combination with a bed, a work supporting table mounted thereon for translation relative thereto, and a grinding wheel carriage carried by the bed for movement toward the work supporting table, of a cross feed mechanism for effecting the movement of the carriage including a ratchet and pawl, a plunger pivotally-carrying the pawl, a reversely oscillatable cam, a lever pivotally mounted at one end and engaging the plunger at the other end and contacting with the cam intermediate its ends, means for effecting the reverse oscillations of the cam for oscillating the lever in one direction and correspondingly reciprocating the plunger, yielding means for shifting the plunger in the opposite direction and returning the lever to its normal position, and means for varying the position of the plunger with respect to the lever, thereby providing lost motion between the plungerand lever so that equal oscillations of the cam and lever efiect variable length of reciprocations of 18. Ina grinding machine of the class described the combination with a bed, a work supporting table mounted thereon for translation relative thereto, and a grinding wheel carriage carried by the bed for movement toward the work supporting table, of a cross feed mechanism for effecting the movement of the carriage including a ratchet and pawl, a plunger pivotally carrying the pawl, a reversely oscillatable cam, a lever pivotally mounted at one end and engaging the plunger at the other end and contacting with the cam intermediate its ends, means for effecting the reverse oscillations of the cam for oscillating the lever in one direction and correspondingly reciprocating the plunger, yielding means for shifting the plunger in the opposite direction and returning the lever-to its normal position, means for varying the position of the plunger with respect to the lever, thereby providing lost motion between the plunger and lever so that equal oscillations of the cam and lever effect variable length of reciprocations of the plunger, and hydraulic actuable means for effecting the reverse oscillations of the cam.

19. In a grinding machine of the class described the combination with a bed, a work supporting table mounted thereon for translation relative thereto, and a grinding wheel carriage carried by the bed for movement toward thework supporting table, of a cross feed mechanism for effecting the movement of the carriage including a ratchet and pawl, a plunger pivotally carrying the pawl, a reversely oscillatable cam, a lever pivotally mounted at one'end' and engaging the plunger at the other end and contacting with the cam intermediate its ends, means for effecting the reverse oscillations .of the cam for oscillating ,3 the lever in one direction and correspondingly reciprocating the plunger, yielding means for shifting the plunger in the opposite direction and returning the lever toits normal position, means for varying the position of the plunger with re- 5. spect to the lever, thereby providing lost motion betweenthe plunger and lever so that equal oscillations of the cam and lever effect variable length of reciprocations of the plunger, hydraulic actuable means for effecting the reverse oscillationsof the cam, hydraulic means for translating the work supporting table, a connection between the work supporting table translating means'and the cam oscillating means whereby the said hydraulic means are simultaneously actuated, and a reversing valve operable by the table for simultaneously reversing the operation of the hydraulic means.

HANS FRITSCHI.

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