JPS6222748B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal grinding device for grinding internal threads formed on the inner surface of a workpiece. To reliably reproduce the position of a grindstone at the time of interruption.

Generally, in a workpiece having a female thread formed on its inner surface, such as a power piston used in a power steering device of an automobile, a ball screw is formed as the female thread. When grinding this ball screw, the grinding wheel used for this grinding accelerates wear relatively quickly because its diameter is extremely small and it has a special shape that corresponds to the spiral groove of the ball screw. For this reason, when the grinding allowance for a screw increases, it becomes impossible to maintain the sharpness of the grinding wheel in a state that does not adversely affect the grinding accuracy without performing dressing even once during grinding of this allowance. equal. Therefore, in order to prevent the deterioration of grinding accuracy, it is necessary to temporarily interrupt the grinding several times during the thread grinding process and perform dressing. What is important in this case is that when thread grinding is resumed after dressing the grindstone, the grindstone must be returned to the same position as when grinding was interrupted.

The present invention was made in view of these points, and includes a grindstone head installed on a base so as to be movable back and forth.
When the rapid feed cylinder provided on the base advances to the grinding position by rapid feed, the forward end of this grindstone head is regulated by the regulating member provided on the feed screw shaft for grinding cutting, and the cutting feed by the feed screw shaft is controlled by the piston of the fast feed cylinder. In addition, a feed screw member is also provided at the connection part with the grindstone that is connected to the piston rod of the rapid-feeding cylinder, and this is driven by the dressing cutting device. An internal grinding device in which when the grinding wheel head is retreated in rapid traverse to dress the grinding wheel, the desired dressing cutting feed is applied to the grinding wheel head by the dressing cutting applying device, and the interrupted position can be returned only by the operation of the rapid feeding cylinder. is to provide.

An embodiment of the present invention will be described below based on the drawings. 1 to 3, reference numeral 1 indicates a bed, and a headstock 3 is mounted and fixed at a predetermined position on a table portion 2 provided on the upper surface of the bed 1. A main spindle 4 is rotatably and slidably supported on the main spindle 3, and a helical motion imparting device 5 attached to the rear of the main spindle 3 is attached to the main spindle 4.
A helical movement mechanism (not shown) built in provides a helical movement commensurate with the thread pitch of the internal thread Wa, which will be described later. Further, a workpiece holder 7 is fixed to the tip of the main spindle 4 via an adapter 6, and a workpiece W having a female thread Wa with a spiral groove formed on the inner surface of a ball screw or the like is housed in the holder 7. and is stably clamped by a clamp device 8 attached to the holder 7.

Further, a base 9 is fixed to the front side of the headstock 3 on the bed 1, and a grindstone head 10 is mounted on a guide portion 9a on the base 9 so as to be slidable in a direction perpendicular to the axis of the workpiece W. At the same time, this whetstone head 10
As shown in FIG. 2, two concentric grooves 11 and 12 are formed in the front vertical wall 10a of the
The frame 1 is fixed by the fixture 13 engaged with 1 and 12.
4 is attached to the vertical wall 10a so that its angle can be adjusted.Furthermore, a grindstone head 15 is attached to the stand 14 so that its position can be adjusted in the direction of the workpiece W.The grindstone head 15 has a motor 16. A rotating whetstone G with a shaft is attached to the front end of a whetstone head 15. The grindstone G is the workpiece W
The internal thread Wa of the workpiece W is ground by adjusting the angle of the grinding wheel head 15.
It is inclined at a predetermined angle corresponding to the lead angle of Wa.

On the base 9 facing the lower surface of the whetstone head 10, a whetstone head rapid feed cylinder 17 is arranged along the movement direction of the whetstone head 10. The rapid feed cylinder 17 includes a cylinder tube 18, support blocks 19 and 20 that horizontally fix and hold both ends of the cylinder tube 18 on the base 9, and a piston 2 that is slidably inserted into the cylinder tube 18.
1, and a piston rod 22 that is integrated with the piston 21 and extends rearwardly through the support block 20, and communicates with the head side of the cylinder tube 18. A nut member 23 that also serves as a cylinder cover is fixed to the opening, and a fast-forwarding cylinder 1 defined by a piston 21 is fixed.
A pressure fluid source P is connected to the left and right chambers 7 via a switching control valve 24. Further, a feed screw shaft 25 for grinding and cutting that is aligned with the axis of the rapid feed cylinder 17 is arranged on the support block 19 side, and one end of this feed screw shaft 25 is connected to the protruding side shaft of the nut member 23. A threaded portion 25a which is rotatably and slidably fitted and supported in the core and extends integrally with the fitting end thereof is screwed into the nut member 23, and further, the threaded portion 25a is fitted into the nut member 23. A shaft portion 25b integrally extended at the tip is relatively rotatably connected to a regulating member 26 that is slidably inserted into the head side chamber of the rapid-feeding cylinder 17, and when the piston 21 moves forward in rapid-feeding, it comes into contact with the regulating member 26 to prevent the piston 2 from moving forward.
1, that is, the forward end of the grindstone head 10 is regulated. The other end of the feed screw shaft 25 is connected to an intermittent notch feeding device 27 provided on the front surface of the bed 1.

The intermittent notch feeding device 27 intermittently rotates the feed screw shaft 25 to provide the grinding wheel head 10 with a cutting feed for grinding. As shown in FIG. 1, the bed 1 has a base body 28 attached to the front surface, and a pinion 29 is rotatably supported on the upper part of the base body 28 by a bearing 30, and the feed screw is attached to the axis of the pinion 29. The other end of the shaft 25 is inserted and supported so as to be relatively rotatable and slidable in the axial direction, and a feed screw shaft whose axis is perpendicular to the axis of the pinion 29 is provided on the side of the base body 28. A rotating cylinder 31 is attached, and a piston rod 33 integral with a piston 32 of the cylinder 31 extends in the tangential direction of the pinion 29, and a rack 34 that meshes with the pinion 29 is formed on the piston rod 33. Further, a regulating member 36 for regulating the retreating end of the piston 32 is screwed onto the head side cap 35 of the cylinder 31 so that its position can be adjusted.
A scale dial 37 is attached to the. Further, a rotary plate 38 is fixed concentrically to the front end surface of the pinion 29, and the position of the rotary plate 38 can be adjusted in the rotational direction with respect to a reference disk 39 splined to the other end of the feed screw shaft 25. The reference disk 39 is combined and integrated by a fixing screw 40, and a scale dial 41 is integrally attached to the reference disk 39. Further, a support member 42 whose axis is oriented in the tangential direction of the rotation plate 38 is fitted onto the upper end of the base body 28, and a rotation plate 38 that passes through the support member 42 in the axial direction.
The rotation regulating member 43 of the cylinder 31 is screwed together so that its position can be adjusted, and the protrusion 38a protruding from the periphery of the rotary plate 38 is brought into contact with the inwardly protruding end of the regulating member 43. The forward end (total cutting feed amount) is regulated. 44 is a scale dial attached to the regulating member 43.

Furthermore, as shown in FIG.
The front and rear chambers 31a, 31 are divided by the piston 32 of
A switching control valve 4 is provided in the flow path between B and the pressure fluid source P.
5 is connected, and this switching control valve 45 and cylinder 3
A pilot pressure operated switching valve 46 and a check valve 47 are connected to the flow path between the rear chamber 31b and the switching valve 46, and a switching control valve 47 is connected between the switching valve 46 and the pressure fluid source P. A valve 48 for metered fluid supply is also connected. This valve 48 includes a piston 50 slidably fitted in a valve chamber 49 formed in its main body 48a, and each time the piston 50 moves based on the switching operation of the switching valve 46, the piston 50 A certain amount of fluid filled in the left or right chamber is transferred to the cylinder 31.
It is designed to be supplied to the rear chamber 31b.

In FIG. 3, a dress cutting feed applying device 51 is provided at the connecting portion of the rapid feed cylinder 17 to the piston rod 22 and the grindstone head 10. The dressing cut feed applying device 51 includes a feed screw member 52 rotatably attached to the outward protrusion of the piston rod 22 of the rapid feed cylinder 17 with axial movement regulated. The coupling member 53 is screwed into the screw hole 53a of the coupling member 53 fixed to the lower surface of the grindstone head 10, and the coupling member 53 is screwed into the screw hole 53a by the bearing members 54 and 55.
is supported for relative rotation and relative sliding in the axial direction, and a gear 5 is further provided at one end of the feed screw member 52.
6 is installed. The pinion 57 that meshes with the gear 56 is rotatably attached to a support member 58 fixed to the rear of the whetstone 10, as shown in FIGS. 3 and 6. A support body 59 is fixed, and a cylinder 60 for dressing cutting, whose axis is oriented in the tangential direction of the pinion 57, is attached to this support body 59, and a piston rod 62 integral with a piston 61 of this cylinder 60 is attached.
extends in the tangential direction of the pinion 57, and the piston rod 62 is provided with the pinion 57.
7, and by moving the piston 61 forward, the pinion 5
7. The feed screw member 52 is rotated via the gear 56 to feed the grindstone head 10 a dress cut in the backward direction. Further, a regulating member 65 for regulating the retreating end of the piston 61 is screwed onto the head side cap 64 of the cylinder 60 so that its position can be adjusted.

In FIG. 6, a switching control valve 66 is connected to a flow path between the front and rear chambers 60a, 60b divided by the piston 61 of the cylinder 60 and the pressure fluid source P. A flow rate control valve 67 is provided in the flow path between the front chamber 60a of the cylinder 60, and a flow rate control valve 67 is provided between the switching control valve 66 and the rear chamber 60a of the cylinder 60.
A pilot pressure operated switching valve 68 and a check valve 69 are connected to the flow path between the switching valve 68 and the pressure fluid source P, and a switching control valve 70 is connected between the switching valve 68 and the pressure fluid source P. Valve 7 for fluid supply
1 is also connected. The valve 71 includes a piston 73 that is slidably fitted in a valve chamber 72 formed in a main body 71a, and each time the piston 73 moves based on the switching operation of the switching valve 68, the valve chamber 72 is moved. A certain amount of fluid filled in the left or right chamber of the cylinder 60 is supplied to the rear chamber 60b of the cylinder 60.

In FIG. 1, reference numeral 74 is a dressing device for dressing the grinding wheel G. This dressing device 74 has a base 75 installed at a predetermined position on the bed 1 facing the grinding wheel G, and a front end surface of the base 75. It is composed of a general roll dresser 78 attached to a rotating shaft 77 of a fixed tool stand 76, and a drive motor 79 installed on the base 75 to rotate the dresser 78, and presses the grindstone G against the dresser 78 to drive the wheel stand 10. By making a notch in the area, dressing can be performed using a plunge cut method.

Next, the operation of the apparatus of the present invention configured as described above will be explained.

First, when the workpiece W is clamped to the workpiece holder 7 by the clamping device 8, the switching control valve 24 is switched to the position, whereby the piston 21 is moved by the pressure fluid supplied from the pressure fluid source P to the cylinder 17. is advanced to the left in FIG. 3, and along with this, the grindstone head 10 is rapidly advanced toward the workpiece W from the backward end position (original position) shown by the imaginary line in FIG. Then, the piston 21 is connected to the feed screw shaft 2.
When the forward end of the grindstone head 10 comes into contact with the regulating member 26 of No. 5 and is regulated, the switching control valves 45 and 47 are switched to their positions. As a result, the switching valve 46 is switched to the position by the pilot pressure,
The pressure fluid supplied from the pressure fluid source P is supplied to the valve 4.
8 into the right chamber of the valve chamber 49 and moves the piston 50 to the left, and a certain amount of fluid filled in the left chamber is introduced into the rear chamber 31b of the cylinder 31 to move the piston 32.
move forward by a predetermined amount. As the piston 32 moves forward, the rotating plate 38 and the reference disk 37 are rotated clockwise in FIG. 5 via the rack 34 and pinion 29. As a result, the feed screw shaft 2
5 is rotated in the same direction and moved to the right by a minute amount in FIG. The table 10 is moved backward and a predetermined grinding depth is applied to the workpiece W.

Thereafter, the spindle 4 is given a helical motion by the operation of the helical motion imparting device 5, and is driven forward to the right in FIG. 2, and is thread-grounded by the grindstone G that rotationally drives the female thread Wa on the inner surface of the workpiece W. When the main shaft 4 is located at the forward end of the traverse and the grindstone G is separated from the threaded end of the internal thread Wa, the switching control valve 4
7 is switched to the position, and as a result, the switching valve 46 is switched to the position by the pilot pressure, and the pressure fluid from the pressure fluid source P flows into the left chamber of the valve chamber 49 of the valve 48, and the piston 50
is moved to the right, and a certain amount of fluid filled in the right chamber of the valve chamber 49 is supplied to the rear chamber 31b of the cylinder 31 through the switching valve 46. As a result, as described above, the feed screw shaft 25 moves to the right and the regulating member 26,
The grindstone head 10 is moved back by a predetermined grinding depth via the piston 21 and piston rod 22. Thereafter, the main spindle 4 is traversed backward while being spirally moved by the spiral motion imparting device 5, and the workpiece W is moved back again.
The internal thread Wa will be ground.

In this way, when the grinding cycle as described above is repeated and the grinding wheel G wears out, the grinding process is temporarily interrupted, the switching control valve 24 is switched to the position, the piston 21 is moved backward, and the grinding wheel head 10 is quickly moved back to the original position. let Thereafter, the switching control valves 66 and 70 in FIG. 6 are switched to the position, whereby the switching valve 68 is switched to the position by the pilot pressure, and at the same time, the pressure fluid source P is switched to the position.
Pressure fluid supplied from the valve chamber 72 of the valve 71
A certain amount of fluid filled in the left chamber is introduced into the rear chamber 60b of the cylinder 60, and the piston 61 is moved forward by a predetermined amount. As the piston 61 moves forward, the feed screw member 52 is rotated clockwise in FIG. 6 via the rack 63, pinion 57 and gear 56.
Along with this, the grindstone head 10 is moved back by the dressing cut amount necessary for grindstone correction by the screw lead of the feed screw member 52, and the grindstone G is cut into the dresser 78. As a result, the grinding wheel G is rotated by the dresser 78.
Dressed in a plunge cut style.

When this dressing operation is completed, the switching control valve 24 is switched to the position again, and the grindstone head 10 is rapidly advanced by the cylinder 17. When the piston 21 comes into contact with the regulating member 26 that is moved together with the feed screw shaft 25, the forward end position of the grindstone head 10 relative to the base 9 is at the feed screw shaft 25.
The grinding wheel G is regulated by the regulating member 26 which moves backward in the same way as when grinding is interrupted, so the grindstone head 10 is located at a position that is retreated by the amount of dress cutting from the position when grinding is interrupted, and the grinding wheel G is thereby moved back to the position when grinding is interrupted. will be accurately reproduced.

From this state, the above-described grinding cycle operation is repeated again, and the piston 32 of the intermittent notch feeder 27 is intermittently and gradually advanced based on the traverse operation accompanied by the spiral movement of the main shaft 4, so that the protrusion 38a of the rotating plate 38 is regulated. When it comes into contact with the member 43, the grindstone head 10
The grinding depth is completed. Thereafter, after the grinding wheel G has been dressed as described above, the grinding wheel head 10 is rapidly advanced, and the workpiece W is spark-out grounded by the traverse operation with zero grinding depth, and the thread grinding process is completed.

When the grinding process is thus completed, the switching control valve 45 is switched to the position, and fluid from the pressure fluid source P is introduced into the front chamber 31a of the cylinder 31, and the piston 32 is moved so that its retreating end is connected to the regulating member 3.
With this backward movement, the feed screw shaft 25 is moved through the rack 34 and the pinion 29.
is rotated in the opposite direction to the cutting feed direction and moved forward (in the direction of arrow A in FIG. 3) by the lead of the threaded portion 25a, and at the same time, the regulating member 26 is also moved forward to return to its original position (cutting start position), Waits to start cutting for the next thread grinding.

In addition, when the grindstone G is replaced with a new one due to the end of its life, the dressing cutting feed applying device 5
1, the switching control valve 66 is switched to the position, fluid from the pressure fluid source P is introduced into the front chamber 60a of the cylinder 60, and the piston 61 moves to the regulating member 6.
5, thereby rotating the feed screw member 52 in the opposite direction to the dressing cutting direction and returning the grindstone head 10 to the dressing cutting starting point.

As described above, in the present invention, when the grindstone head installed on the base so as to be movable back and forth is advanced to the grinding position in rapid traverse by the rapid traverse cylinder provided on the base, the forward end of the whetstone head is connected to the feed screw shaft for grinding cutting. The cutting feed can be controlled by a regulating part provided in the feed screw shaft, and the cutting feed is applied to the grindstone head via the piston of the rapid-feeding cylinder to enable internal grinding of the workpiece. A feed screw member is also provided at the joint with the table, so that when the grindstone head is retreated in rapid traverse to dress the grindstone, the feed screw member is driven by the dressing cut feed applying device to apply the desired dress cut feed to the grindstone head. Because of this configuration, the grinding wheel is dressed during the internal grinding process.
By simply operating the rapid-feed cylinder to return the grinding wheel head to the grinding position, the position of the grinding wheel at the time of interruption of grinding can be reliably reproduced, and internal grinding of the workpiece can be continued without being affected by dressing. In addition to this, it is also possible to make the grinding device more compact since the dressing cutting feed applying device is provided at the joint between the rapid feed cylinder and the grindstone head.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an internal grinding device according to the present invention, Fig. 2 is an enlarged view showing the positional relationship of the headstock and grindstone head seen from the arrow in Fig. 1, and Fig. 3 is a plan view of the internal grinding device of the present invention. 4 is an enlarged cross-sectional view of the line in FIG. 1, FIG. 5 is a cross-sectional view of the line in FIG. 4, and FIG. 6 is a cross-sectional view of the line in FIG. 3.
FIG. DESCRIPTION OF SYMBOLS 1... Bed, 3... Headstock, 4... Main spindle, 5... Spiral motion imparting device, 9... Base, 10... Grinding head, 15
... Grinding wheel head, 17... Rapid feed cylinder, 21... Piston, 22... Piston rod, 23... Nut member, 25... Feed screw shaft, 25a... Threaded portion, 26...
Regulation member, 27... Intermittent notch feeding device, 51... Dress notch feeding device, 52... Feed screw member,
53...Coupling member, 56...Gear, 57...Pinion,
60...Cylinder, G...Whetstone, W...Workpiece, Wa...
Female thread.

Claims (1)

[Claims] 1. A headstock installed on a bed and rotatably holding a workpiece; and a grindstone head located on the bed at the front of the headstock and slidably guided in a direction perpendicular to the axis of the workpiece. a grindstone head having a grindstone installed on the grindstone for grinding the inner surface of the workpiece; a dressing device installed on the bed on the backward side of the grindstone corresponding to the grindstone; A rapid-feeding cylinder is disposed on the bed in line with the moving direction of the table and moves the grinding wheel head back and forth between the grinding position and the dressing position; a feed screw shaft having one end inserted into the interior of the rapid feed cylinder; a regulating member that is supported on the tip of the feed screw shaft to restrict axial movement and allow relative rotation, and that restricts the forward end of the piston; an intermittent notch feeder that rotates the feed screw shaft to change the forward end position of the piston by the regulating member to perform a cutting operation; and the grindstone, which is held rotatably at the outwardly projecting end of the piston rod of the rapid traverse cylinder. An internal grinding device comprising: a feed screw member screwed onto a stand; and a dressing cut imparting device that rotates the feed screw member and applies a dress cut to the grindstone head when the grindstone head is fast-forwarded and retreated.