US2127856A - Grinding machine - Google Patents

Description

1938. H. L. BLOOD 232L856 GRINDING unlit-NE Filed Dec.. 21, .1936 4 shoetmnt 1 223, 1938. H. L. BLOOD GRINDING MACHINE Filed Dec. 21, 1936 4Shge t55hegti-2 m 1 i l M a a E M m p 5 8. 8 7 7 fi M J 2 M Hm a. .m.. w 5 y w 5 aw w 7 fl 9w 6 4. 4 4.

Aug. 23, 1938. H. L. BLOOD GRINDING MACHINE Filed Dec. 21, 1936 4 Sheets-Sheet 3 I, WW

Aug. 23, 1938. H. L. BLOOD GRINDING MACHINE FiledDec. 21, 1936 4 sheets-sheet 4 Q JH fi 9 m m 23 f m 5. 2% 2 m w J H Mai H 1 J 1 m J 1 Patented At 23, 1938 GRINDING MACHINE Harold L. Blood, Worcester,'Mass., assignor to The. Heald Machine Company, Worcester, Mass.', a corporation of Massachusetts Application December 21, 1936, Serial No. 116,879

19 Claims.

The present invention relates to grinding machines and particularly to a machine in which the relative crossfeed movement between the grinding wheel and the workpiece may take place at a 5 rapid rate until the grinding wheel engages the workpiece.

In grinding machines operating upon cylindrical or tapered surfaces the grinding wheel is normally given a crossfeed movement relative to the workpiece to bring the wheel and workpiece into grinding contact and thereafter to procure successively deeper and deeper cuts in the workpiece until the latter reaches the desired finished size. One of the principal objects of the present inven-- tion is to provide for reducing the rated crossfeed movement when the wheel and workpiece come into contact independently'of the unfinished workpiece size.

In internal grinding machines it is essential that the workpiece and the grinding wheel, at the beginning of the grinding operation, be positioned transversely of the machine relative to each other, so that the grinding wheel may enter the workpiece bore when either the grinding 2,; wheel or the workpiece is given an axial movement. After the wheel is positioned within the bore of the workpiece a relative transverse movement brings the grinding wheel and workpiece into grinding contact and for reducing the inoperative time of each grinding operation this transverse movement must take place as rapidly as possible. A further object of the present invention is accordingly to provide in internal grinding machines for a rapid crossfeed movement with a 33 provision for reducing the rate of this movement immediately upon engagement between the wheel and workpiece and independently of the unfinished size of the workpiece- In a copendingapplication filed by Schmidt and Blood, Serial No. 68,291, filed March 11, 1936, is disclosed a structure by which the rate of crossfeed movement may be reduced upon engagement between the wheel and the workpiece, and this structure incorporates a grinding wheel which is a conductor of electricity and forms part of a circuit which is closed upon engagement between the wheel and the workpiece. This arrangement is entirely satisfactory in operation, but there are occasions when such an arrangement is not de- 50 sirable, either by reason of the type of workpiece, the latter not being a conductor, or where the coolant forms such an insulation that asuitable electrical contact between the wheel and the of the present invention is to provide for the response to movement of the wheelhead relative to";

its support with this movement produced by the pressure between the grinding wheel and+ the work. The arrangement is such that a very slight amount of wheelhead movement is necessary for procuring the desired reduction in the rate of transverse movement and it will be understood that the workhead can be alternatively mounted for the movement necessary to obtain this reduction in the transverse movement.

Other and further objects and advantages of the invention will more fully appear from the following'detailed description taken in connection with the accompanying drawings in which- Fig. 1 is a 'front elevation of a machine embodying the invention.

Fig. 2 is a plan view of the machine of Fig. 1.

Fig. 3 is a vertical section substantially along the line'3-3 of Fig. 2.

Fig. 4 is a vertical section substantially along the line 4-4 of Fig. 3, with parts broken away to show the crossfeed mechanism more clearly.

Fig. 5 is an end view of the wheelhead and associated mechanism with parts broken away.

Fig. 6 is a fluid pressure diagram.

Fig. 7 is a. wiring diagram.

Like reference characters refer'to like parts in the different figures.

Referring first to Fig. 1, the machine has the usual reciprocatory table I provided in an internal grinding machine; either the grinding wheel or the workpiece to be ground is carried on the table, the reciprocations of the latter operating in either case to produce a relative translatory movement' between the wheel and the workpiece. In the construction shown the table supports and carries a workhead 2 and the wheelhead 3 is mounted on a bridge 4, Fig. 3, which spans the guideways 5 provided by the base 6 of the machine for the movements of the table. The grinding wheel 1 is carried on a spindle 8 journalled'in the wheelhead and is suitably rotated at a high rate of speed by any well known mechanism, which in the present instance consists of a motor, not shown, in the base of the machine connected by a belt, to a pulley 9 on the spindle.

The workpiece (1, Figs. 1 and 3, is mounted in a suitable work-supporting structure which may be in the form of a chuck III carried on a spindle II journalled in the work-head. The chuck is preferably driven at a relatively slow rate of speed from a motor I2 connected to the spindle I I by a belt I3. The clutch mechanism I4, of any well known construction, provides for stopping the rotation of the chuck without interfering with the operation of the motor I2, and this mechanism is under the control of a handle I5 easily accessible to the operator of the machine. The reciprocations of the table I to cause the desired relative traverse between the rotating grinding wheel and the work-supporting structure are imparted in any well known manner, as by the use of fluid pressure controlling and reversing mechanism, one type of which is described in the Blood and Burns Patent .No. 2,011,705, dated August 20, 1935. It is suflicient to note for the purpose of the present application that reversal of the table is procured at each end of the normal working stroke by spaced reversing dogs I5 and I! which are carried by blocks I8 and I3 adjustably mounted on the front of the table I and adapted alternately to engage and move a reversing lever 20. The reversing lever is connected by suitable mechanism to a reversing valve 2I, Fig. 6. The reversing lever 20, during the grinding operation, when the grinding wheel is in the bore of the workpiece, is so located as to be engaged alternately by the reversing dogs.

Referring now to Fig. 6, the pump 22, driven by a motor 23, directs fluid under pressure from a tank 24 through a pipe 25 to the casing 26 in which the reversing valve 2I is positioned. The casing 25 has an inlet port 21 to which the pipe 25 is connected and also has spaced outlet ports 23 and 23 connected by pipes 30 and 3I respectively to the left and right hand ends of a cylinder 32 mounted in the base of the machine. A piston 33 slidable in the cylinder has a piston rod 34 connected to a depending lug 35 on the table I. The reversing valve alternately directs fluid under pressure to the outlet ports 23 and 23 and at the same time connects the opposite outlet port to an exhaust port 35 suitably connected to the tank.

Referring now to Fig. 3, the crossfeed movement between the workpiece and the grinding wheel is obtained by transverse movement of the wheelhead 3 on the bridge 4. Movement of the cross slide 31, Fig. 3, on which the wheel-head is mounted, is eflected by rotation of the crossfeed screw 35, which is held against endwise movement by anti-friction bearings 33 on the rearward end thereof. The crossfeed screw engages an internally threaded portion of the cross slide for effecting the transverse movement thereof. 0n the forward end of the cross feed screw 35 is mounted a gear M which meshes with a, pinion 42 secured against turning movement on a shaft 43 journalled in a housing 44 for the cross feed mechanism. Also secured to the shaft 43 in spaced relation to the gear 42 is a ratchet wheel 45 engageable by spaced oppositely directed pawls 45 and 41, Fig. 4, carried by an annular member 43 secured against turning movement on a sleeve 43 journalled on the shaft 43. The sleeve 49 has an integral pinion 50 engageable by a rack 5 I horiaontally slidable in the casing 44, said rack being held in engagement with the pinion by a bearing 52. The rack 5I is shifted bya fluid pressure mechanism hereinafter described in detail, and

procures through the pawl and ratchet arrangement a rotation of the shaft 43, and accordingly a rotation of the crossfeed screw. Manual rotation of the crossfeed screw is by a hand wheel 43' on the end of the shaft 63.

The pawl and ratchet arrangement is fully described in the Guild Patent No. 1,971,138, dated August 21, 1934. It is sufllcient to note for the purpose of the present application that this double pawl arrangement permits, during the return of the cross slide to original position, in readiness for a subsequent grinding operation, a compensation for the reduction in size of the grinding wheel as a result of wear, and the dressing operation performed thereon during the preceding grinding operation. With reference again to Figs. 3 and 4, it will be noted that both of the pawls are normally held in operative engagement with the ratchet by a spring 53, and that the pawl 41 is operative during the crossfeed movement and the pawl 46 is operative during the retraction of the crossfeed movement, the latter involving a counterclockwise rotation of the member 43. The pawl 46 is rendered inoperative during a part of the movement of the annular member 48 in the counterclockwise direction so that the cross slide is retracted a slightly shorter distance than it is moved forward during the crossfeed movement.

To effect this compensatory movement the shaft 43 has journalled thereon an arm 54 having a gear segment on the outer end thereof. The gear segment engages with a pinion 55 on a shaft 51 journalled in the front wall of the housing 44 and the outer end of the shaft 51 has a knurled knob 58 by which said shaft is turned for shifting the position of the arm 54. Integral with the arm 54 is a cam 53 in a position for engagement with a pin 50 on the pawl 45 just before the termination of the crossfeed movement. Thus, during the first part of the retraction of the crossfeed movement the pawl 46 is inoperative and rotation of the annular member 48 procures no corresponding movement of the ratchet wheel until the pawl 45 is released by the cam 59. During the remainder of the counterclockwise movement of the member 43 the retraction of the crossfeed movement takes place.

Referring now to Figs. 4 and 6, the rack 5I is carried on the end of a. piston rod 5I extendin from a piston 52 slidable in a horizontally positioned cylinder 63 mounted on the front of the bridge. Fluid under pressure is directed alternately to opposite ends of the cylinder for procuring the crossfeed movement and the retraction thereof. pressure from the pipe 25 passes through a pipe 54 to the inlet port 55 of a reversing valve casing 55 for a reversing valve 61 for the crossfeed mechanism. An outlet port 68 in the casing 55 is connected by a conduit 69 to the left hand end of the cylinder 63 and a second outlet port III is connected by a conduit II and suitable valve mecha-- nisms hereinafter described, to the right hand end of the cylinder 63. An exhaust port I2 for the reversing valve casing is suitably connected to the tank 24 and provides for exhaust of fluid from the cylinder. 7

The structure above described is similar to structure already disclosed and claimed in prior patents and pending applications and is not, of itself, the present invention. The latter involves, in connection with the above or similar grinding machine elements, the attainment of the objects and novel features above outlined. In accordance As shown in Fig. 6, fluid under Ill with the present invention the movement of the wheelhead resulting from engagement between the grinding wheel and workpiece during the 'crossfeed movement, is used to procure a change in the grinding operation. This change, in the structure described for one embodiment of the invention, is a reduction in the rate of crossfeed movement, although it will be apparent that other changes in the grinding operation may be controlled or procured by similar mechanism.

With reference now to Figs. 5 and 6, the wheel-- head 3 is supported for rocking movement on the cross-slide 31 by means of flat springs I3 attached at their opposite ends, as by bolts I4, to a slide 15 secured in the cross-slide. The springs 13 are centrally connected by suitable bolts 16 to the wheelhead and the springs are shaped to provide for a small amount of oscillatory movement of the wheelhead on the slide I5, the wheelhead rocking about lugs 11 on the slide 15 in line with the bolts I6.

Referring again to Fig. 5, the cross-slide 31 has mounted thereon forwardly of the wheelhead, a housing I6 on which is mounted, for rocking movement, a lever I9. The support for this lever preferably comprises one or more fiat springs 80 connected at one end to the housing 18 and at the opposite end to one end of the lever I9. The lever I9 is connected between its ends thereof to the wheelhead 3 by similar fiat springs Rocking movement of the wheelhead 3 in the direction of the arrow 82, resulting from engagement between the grinding wheel and the workpiece will procure a clockwise swinging movement of the lever H by which the change in the grinding operation is effected. The swinging movement of the wheelhead is limited by an adjustable bolt 83 on the housing l6.

The lower end of the lever I9 has an electrical contact 94 (shown in Fig. 7 as attached directly to the wheelhead) and this contact engages with a stationary contact 85 on the housing "I8 when the grinding wheel engages the workpiece. Reierring now to the wiring diagram of Fig. 7, a source of power is represented by the transformer 06. One side of the secondary winding 81 of the transformer'is connected by a lead 88 to the contact 04 on the lever I9 (on the wheelhead, Fig. 6).

The other'side of the secondary winding 81 is connected by a lead 89 to a contact 90 of a switch 9|, the other contact 92 of the switch being connected by a lead 83 to one'term-inal of a solenoid 94. The other terminal of the solenoid is connected by a lead 95 to the contact 85. The armature 96 of the solenoid 94 is connected by a link 31 to the lever I9 and energization of the solenoid by engagement between contacts 84 and 85 thus urges the armature to the left to hold the contacts in engagement and to hold the wheelhead against the adjustable bolt 83.

Integral with the armature 96 of the solenoid 34 is a valve 98 in a casing 99 forming an integral part of the housing I8 and this valve is shifted to the left when the solenoid is energized for materially reducing the rate of crossfeed movement. With reference to Fig. 6, the casing 99 has a part I00 connected by a conduit IM to the conduit II and a second port I02 connected by a conduit I03 to the right hand end of the cylinder 63. A reduced portion I04 of the valve normally provides fluid connection between the ports I00 and I02 so that the crossfeed movement occurs at a maximum rate determined by a main throttle valve I05 in the conduit 'II. solenoid 94 is energized, the fluid connection When the through the valve 98 is cut off and fluid then enters the cylinder 63 at a reduced rate-through a valve. I 06.

Again referring to Fig. 6, the valve I06 is. positioned in a casing I0'I in a block I08 mounted on the front of the bridge directly above the cylinder 63, as shown in Fig. 4. The conduit. II is connected toa channel I09 in the block I08 which intersects spaced bores in which a rough feed valve H0 and a fine feed valve III are respectively positioned. The casing I0I has a port II2 communicating with the end of the valve I I0 and a spaced port I I3 communicating with the valve III. With the valve I06 in the normal position, which is the position at the beginning of the grinding operation, a reduced portion II4 of the valve I06 provides a connection between the port H2 and a channel I I5 in the'casing I01, block I08 and cylinder 63, this channel communicating with the right hand end of the cylinder 63. The channel I I5 is represented in part, in Fig. 6, by a conduit I I5, for the sake of clarity. Thus when the fluid connection. through the valve 98 is cut ofi, as above-stated, the crossfeed movement occurs at a relatively slow rate, as determined by the setting of the rough feed valve I I0.

Subsequentto the shifting of the valve 98, and during the grinding operation, the valve I06 is shifted to the right, for reducing the rate of crossfeed movement still more. When this occurs the connection from the port 2 to the channel H5 is cut ofi and a reduced portion IIG of the valve I06 provides a connection between the port I I3 and a branch channel I I1 communieating with the channel II5. During the remainder of the grinding operation the crossfeed movement occurs at an extremely slow rate determined by the setting of the fine feed valve III. The shifting of the valve I06 is procured by a cam H8, Fig. 4, on the member 48, this cam, during the grinding operation, engaging with a roller II9 on the end of a plunger I20 in line with the valve I06. Movement of the plunger to the left beyond the position of Fig. 4 is limited by a cap. HI and the valve I06 is held against the plunger by a coil spring I22 .in a recess I23 at the right hand end of the valve.

In the operation of the machine, the workpiece is loaded ;while the table is inthe position shown, and the workpiece and grinding wheel are'then brought into operative position by shifting a lever I24 on the front of the machine, this lever being suitably connected to the table reversing valve 2|. As' the table approaches its operative position, with the grinding wheel located inthe bore of theworkpiece, the valve 61 is suitably shifted from the position shown-into its opposite position for directing fluid through the valve 98 to the crossfeed cylinder 63. The valve 61 may be automatically shifted, as for example in response to the table movement.

The crossfeed movement, being procured by.

rate of crossfeed movement by cutting off the flow of fluid through the valve 98.

The grinding operation then continues at the rate determined by the rough feed valve I I0 and subsequently at a rate determined by the fine feed valve Hi, until the workpiece reaches a predetermined size. The grinding operation may be under the control of any suitable mechanism, as for example, the mechanism disclosed in the above cited Blood and Burns Patent No.-2,011,705,

In any event the grinding operation is termi-' "resiliency of springs 13, and the valve 98 is thus restored to'the position of this figure for exhaust of the fluid from the cylinder 63 through this valve.

From the foregoing it will be apparent that the present invention provides a mechanism by which a change in the grinding operation is effected upon engagement between the grinding wheel and the workpiece. By the arrangement shown the change involves a reduction in the rate of crossfeed movement procured by a movement of the wheelhead relative to the machine. By this arrangement the wheel may be moved laterally of the workpiece at a maximum rate until it comes in contact with the workpiece.

I claim,

1. In a grinding machine, a spindle having a wheel thereon, a member in which said spindle is journalled, a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means for supporting one of said members for movement relative to the supporting structure upon engagement between the wheel and the workpiece, and means responsive to said movement relative to the supporting structure for procuring a change in the machine operation.

2. In a grinding machine, a spindle having a wheel thereon, a member in which said spindle is journalled, a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means for supporting one of said members for movement relative to the supporting structure upon engagement between the wheel and the workpiece, and means responsive to said movement relative to the supporting structure for procuring a change in the rate of relative movement between the members.

3. In a grinding machine, a spindle having a wheel thereon, a member in which said spindle is journalled, -a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means for supporting one of said members for movement relative to the supporting structure upon engagement between the wheel and the workpiece, and means responsive to said movement relative to the supporting structure for procuring a reduction in the rate of relative movement between the members.

4. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means for supporting one of said members for movement relative to the supporting structure upon engagement between the wheel and the workpiece, and means responporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means for supporting one of said members for movement relative to the supporting structure in response to engagement between the wheel and the workpiece, and means responsive to said movement relative to the supporting structure for procuring a reduction in the rate of relative movement between the members, said last means also providing for locking the movable member against further movement relative to the supporting structure during the remainder of the grinding operation.

6. In a grinding machine, a spindle having a wheel thereon, a member in which said spindle is journalled, a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means for supporting one of said members for movement relative to the supporting structure therefor upon engagement between the wheel and the workpiece during the said relative movement, and hydraulically actuated means movable in response to said movement relative to the supporting structure for procuring a change in the machine operation. I

7. In a grinding machine, a spindle having a wheel thereon, a member in which said spindle is journalled, a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means for supporting one of said members for movement relative to the supporting structure therefor upon engagement between the wheel and workpiece during said relative movement, a valve means for reducing the rate of relative movement between the members, and electrically actuated means energized in response to movement of the movable member relative to the supporting structure for shifting said valve.

8. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein,

means for procuring a relative movement between said members, means for supporting one oi said members for movement relative to the supporting structure therefor upon engagement between the wheel and workpiece during said relative movement, hydraulically actuated means for procuring a change in the machine operation, and means responsive to the movement of the movable member relative to the supporting structure for locking the movable member against further movement relative to the supporting structure, and for actuating said hydraulically actuated means. v

9. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means for supporting one of said members-for movement relative to the supporting structure therefor upon engagement between the wheel and workpiece during said relative movement, hydraulically actuated means for procuring a change in the machine operation, and electrically actuated means. responsive to said movement of one of said members relative to the tive to the supporting structure and for, ener-- gizing said hydraulically actuated means.

10. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein, a cross slide on which one of said members'is mounted for a crossfeed movement between said 10 members, means for supporting one of said members for a slight rocking movement relative to the supporting structure when the grinding wheel engages the workpiece in the work-supporting member, and means responsive to said rocking 15 movement for changing the rate of crossfeed movement.

11. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein,

20 a cross slide on which one of said members is mounted for a crossfeed movement between said members, means for supporting one of said members for a slight rocking movement relative to the supporting structure when the grinding wheel 25 engages the workpiece in the work-supporting member, fluid pressure actuated means for moving the cross slide, a valve for controlling the fluid pressure actuated means and electrically actuated means responsive to said rocking move- 30 ment for shifting said valve.

12. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein, a cross slide on which one of said members is mounted for a crossfeed movement between said members, means for supporting one of said members for a slight rocking movement. relative to the supporting structure when the grinding wheel engages the workpiece in the work-supporting member, means responsive to said rocking movement for changing the rate of crossfeed movement and for locking the member against further rock- .ing movement during the remainder of the grinding operation.

13. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a work-piece mounted therein,'a cross slide on which one of said members is mounted for a crossfeed movement between said members, means for supporting one of said members for a slight rocking movement relative to the supporting structure when the grinding wheel engages the workpiece in the work-supporting member, fluid pressure actuated means for moving the cross slide, a valve for controlling the fluid pressure actuated means, and electrically actuated means responsive to the rocking movement for locking the member against further rocking movement during the remainder of the grinding operation and for shifting said valve.

14. In a grinding machine, a wheel supporting member havinga wheel thereon, a work-supporting member, means for procuring a feeding moveg ment between said members, means for supporting one of said members for a rocking movement in the machine operation.

15. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member, means for procuring a feeding movement between said members, means for supporting one of said members for a rocking movement relative to the supporting structure when the grinding wheel engages a workpiece in the work-supporting member, and means responsive to said rocking movement for procuring a change in the rate of feeding movement.

16, In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member, means for procuring a feeding movement between said members, means for supporting one of said members for a rocking movement relative to the supporting structure when the grinding wheel engages a workpiece in the worksupporting member, means responsive to said rocking movement for procuring a change in the machine operation and for locking the rockable member against rocking movement in response to said rocking movement.

17. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting members, means for procuring a feeding movement between said members, means for supporting one of said members for a rocking movement relative to the supporting structure when the grinding wheel engages a workpiece in the worksupporting member, means responsive to said 'rocklng movement for procuring a change in the supporting member, hydraulically actuated means for procuring a relative movement between said members, means for supporting one of said members for a rocking movement relative to the supporting structure when the grinding wheel en-.

gages a workpiece in the work-supporting member, a valve for controlling said hydraulically actuated means and electrically actuated means responsive to the rocking movement for shifting said valve.

19. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member, hydraulically actuated means for procuring a relative movement between said'members, means for supporting one of said members for a rocking movement relative to the supporting structure when the grinding wheel engages a workpiece in the work-supporting member, a valve for controlling said hydraulically actuated means, and means responsive to the rocking movement for locking the rockable member against further rocking movement and for shifting said valve.

, HAROLD IL. BLOOD.

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