JPH11347816A - Work drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize grasping force of a pair of grasp pawls to restrain shake of a work and improve working accuracy. SOLUTION: A work W is supported with a headstock center 2 and a tailstock 4 therebetween, and it is grasped with a drive device 5 to be rotated. A chuck main body 9 is fitted to a drive disc 8, and a pair of swing bodies 12 are swingably in a plane containing the center axis supported with the positions spaced by 180 deg. from the main body 9. Claw holders 20 are connected to the bolts 17 of the respective swing bodies 12, and grasp pawls 23 are fitted to the respective holders 20. The claw holders 20 are guided in the plane meeting at right angles with the center axis through two rods 27, and they are opened/closed interlocking with the swing bodies 12. Springs energizing the grasp pawls 23 in the closing direction are insertedly fitted to the rods 27. An annular shifter 35 is combined with a cylinder 32, and the shifter 35 drives the swing bodies 12 in the opening direction of the grasp pawls 23. A cutout part 47 in which the finger 45 of a work locator goes in and out is provided on a part of the shifter 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work drive device for a machine tool, which grips and rotates a work supported between a pair of centers.

[0002]

2. Description of the Related Art When a relatively long work is processed by a grinder or a lathe, the work is usually supported between a headstock center and a tailstock center by a drive device mounted on the headstock side. The work is gripped and rotated. As a drive device, a floating type chuck in which a pair of gripping claws are incorporated in a floating unit that separates from a chuck body is conventionally known (utility model 2537).
958). In this chuck, a floating unit is supported by a chuck body via a pair of swinging arms, and each arm is urged in a closing direction of a gripping claw by a spring, and is driven by a fluid pressure cylinder in a direction in which the gripping claw is opened. Is done.

[0003]

However, according to the conventional work drive device, since the spring for biasing the gripping claw in the closing direction is provided on the swing arm side, the spring force is applied from the swing arm to the grip claw. Fluctuates due to the frictional resistance of a large number of contact parts up to, the gripping force of each gripping claw tends to be uneven,
In particular, when machining a small-diameter long work, there is a problem that the work is run-out and adversely affects the machining accuracy.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a work drive device capable of equalizing the gripping force of a pair of gripping claws, suppressing the swing of the work, and improving the processing accuracy.

[0005]

In order to solve the above-mentioned problems, a work drive device of the present invention is a device for gripping and rotating a work supported between a pair of centers,
A chuck body that is rotated around one center, a pair of oscillators that are swingably supported in a plane that includes the axis of the center at a position that is symmetrical to the axis of the center of the chuck body, and interlocks with each oscillator Claw holders to be opened and closed, gripping claws attached to each claw holder, a guide member for guiding the claw holder in a plane perpendicular to the axis of the center, and a grip provided between the guide member and the claw holder It comprises a spring member for urging the pawl in the closing direction and means for driving the rocking body in the opening direction of the gripping pawl (Claim 1).

Here, the driving means includes an annular member which engages with each rocking member outside the claw holder and a center axis line for centering the annular member in order to surely open and close the pair of gripping claws with the same amount of movement. A hydraulic cylinder driven in the direction (claim 2). Further, in the configuration in which the claw holder is surrounded by the annular member, a notch portion through which the work locator enters and exits is provided in a part of the annular member so that the work can be measured without hindrance using the end surface of the work on the chuck body side as a reference plane ( Claim 3).

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a work drive device for a grinding machine will be described below with reference to the drawings. As shown in FIG. 1, in this grinding machine, a small-diameter and long work W (for example, an injection nozzle) is supported between a center 2 on a headstock 1 side and a center 4 on a tailstock 3 side. The outer peripheral surface of one end of W is gripped and rotated by the drive device 5 provided on the headstock 1 side, and the stepped cylindrical surface of the work W is ground by the angular whetstone 6 provided on the whetstone stand (not shown). ing. A spindle 7 and a drive disk 8 are supported on the headstock 1 by a spindle motor (not shown) so as to be rotatable around the same axis. A center 2 is inserted into the tip of the spindle 7, and a front face of the drive disk 8 is provided. Is mounted so that the chuck body 9 of the drive device 5 rotates around the center 2.

At a position 180 ° away from the chuck body 9, support pieces 11 project forward, and each support piece 11 is provided with a symmetrical rocking body 12 by a pin 13 oscillating in a plane including the axis of the center 2. It is movably supported. Each of the pair of swinging members 12 includes a rearward arm 14 and an outward arm 15, and a stopper 16 that engages with the inner peripheral surface of the chuck body 9 when the main shaft 7 rotates is attached to the tip of the rearward arm 14 so as to be position-adjustable. Have been. A bolt 17 is screwed onto the front surface of each rocking body 12, and a floating unit 18 of the drive device 5 is installed between the two bolts 17.

As shown in FIG. 2, the floating unit 18 is provided with a pair of symmetric claw holders 20. These holders 20 are connected to the bolts 17 by long holes 21 in the center, and coil springs 22 (see FIG. 1)
As a result, it is lightly pressed against the head of the bolt 17, and is opened and closed around the work W in conjunction with the rocking body 12. A gripping claw 23 is exchangeably attached to each claw holder 20 by a bolt 24, and a V-shaped gripping surface 25 for gripping the workpiece W is formed on a relative surface between the gripping claws 23.

Two guide rods 27 serving as guide members for guiding the pair of claw holders 20 in a plane orthogonal to the axis of the center 2 are provided on both sides of the floating unit 18.
Is provided. These rods 27 are attached to the claw holder 20.
Are slidably inserted at both ends, and collars 28 for retaining are fixed to both ends. Collar 28 and claw holder 20
A coil spring 29 as a spring member is fitted into the guide rod 27, and the gripping claw 23 is constantly urged in the closing direction by the spring force.

On the other hand, as shown in FIG. 1, near the headstock 1, a hydraulic cylinder 3 is placed on a table 31 of a grinding machine.
2 are installed. The piston rod 33 of the fluid pressure cylinder 32 is disposed parallel to the axis of the center 2, and a shifter 35 is connected to a front end thereof via a bracket 34. The shifter 35 is provided outside the pawl holder 20 for the oscillator 12.
As shown in FIG. 3, by driving the shifter 35 by the fluid pressure cylinder 32 rearward in the axial direction of the center 2 as shown in FIG.
To move the claw holder 20 in the opening direction,
3 is configured to be dissociated from the work W.

An adjusting bolt 36 is attached to the outward arm 15 of the rocking body 12 for changing the engagement position between the rocking body 12 and the shifter 35 to adjust the opening amount of the claw holder 20. . A plurality of protrusions 37 for restricting rotation of the bracket 34 are provided on the front end surface of the fluid pressure cylinder 32. Dog 3 on bracket 34
The fluid pressure cylinder 32 is provided with a limit switch 39 for checking whether the gripping claw 23 is open or closed according to the position of the dog 38. A dog 40 is fixed to the driving disk 8, and a proximity switch 41 that detects the dog 40 and outputs a signal for stopping the spindle 7 at a fixed position is mounted on the headstock 1.

As shown in FIGS. 4 and 5, the grinding machine according to this embodiment includes a work locator 43 for measuring the work W on the side of the chuck body 9 on the headstock 1 side as a reference position, and a tailstock. A sizing device 44 for measuring the outer diameter position of the work W is provided on the table 3 side. The work locator 43 for measuring the reference position is provided with a contact 46 at the tip of the finger 45 for contacting the rear end face of the work W. A cutout 47 into which the finger 45 of the locator 43 enters and exits when the main shaft 7 is stopped at a fixed position is provided in a part of the shifter 35.

In the work drive device 5 having the above-described structure, when the work W is to be attached or detached, first, the shifter 35 is retracted by the fluid pressure cylinder 32 as shown in FIG.
The swinging body 12 is swung to open the claw holder 20 against the spring force of the coil spring 29, and the gripping claw 23 is disengaged from the work W. Next, as shown in FIGS. 1 and 2, the center 4 of the tailstock 3 is retracted, the processed work W is removed, and the unprocessed work is supported between the centers 2 and 4. 32, the shifter 35 is moved forward and separated from the oscillating body 12, and the claw holder 20 is moved by the spring force of the coil spring 29.
Is closed, and the workpiece W is gripped by the gripping claws 23. In this case, the pair of rockers 12 are rocked at equal angles by the annular shifter 35, so that the two claw holders 20 can be reliably opened and closed with the same amount of movement.

Then, after confirming the fixed position stop state of the spindle 7 based on the signal of the proximity switch 41, the position of the reference end face of the work W is measured. At the time of this locating, as shown in FIGS. 4 and 5, first, the finger 45 of the work locator 43 enters the inside of the shifter 35 from the notch 47 by moving the grindstone base in the X-axis. The contact 46 is brought into contact with the rear end face of the workpiece W by the axial movement. In this state, the position of the reference end face of the work W is measured, and the locate data is transferred to an NC device (not shown).
After that, the table 31 and the grindstone table are moved in the opposite direction, and the work locator 43 is returned to a position where the finger 45 and the contact 46 do not interfere with the shifter 35 as shown in FIG. In this way, even when the reference end surface of the work W is behind the gripping position and inside the shifter 35, the locating work of the work W can be performed without any trouble.

At the time of machining the work W, first, the NC device checks and compares the locate data and the stored data to relatively position the table 31 and the grindstone table. Then, the NC device is integrated with the driving disk 8 by the spindle motor. The chuck body 9 is rotated, and the power of the motor is transmitted to the work W via the oscillating body 12, the bolt 17, the claw holder 20, and the gripping claw 23, and the work W is rotated, and the stepped cylindrical surface is rotated by an angular grindstone. Grind with 6. At this time, since the claw holder 20 is urged in the closing direction by the spring force of the coil spring 29 directly acting on the claw holder 20, the grasping force of the two grasping claws 23 is equalized, and the swing of the work W is suppressed. In particular, when machining a small-diameter long workpiece, it can be ground with high precision.

The present invention is not limited to the above-described embodiment, and may be applied to a lathe work drive device by appropriately changing the shape and configuration of each part without departing from the gist of the present invention. It is also possible.

[0018]

As described above, according to the first aspect of the present invention, the pair of claw holders are urged in the closing direction by the spring force of the spring member directly acting on the pair of claw holders. An excellent effect of equalizing the gripping force, suppressing the runout of the work, and improving the processing accuracy is achieved.

According to the second aspect of the present invention, since the driving means of the claw holder is constituted by the fluid pressure cylinder and the annular member, the pair of swinging members are swung at an equal angle by the annular member, and the two gripping claws are moved. There is an effect that the opening and closing can be reliably performed with the same moving amount.

According to the third aspect of the present invention, since the notch portion through which the work locator enters and exits is provided in a part of the annular member, even when the reference end surface of the work is behind the gripping position and inside the annular member, There is an effect that the work locating work can be performed without any trouble.

[Brief description of the drawings]

FIG. 1 is a sectional view of a grinding machine showing one embodiment of the present invention.

FIG. 2 is a front view showing a work drive device of the grinding machine.

FIG. 3 is a sectional view showing the operation of the work drive device.

FIG. 4 is a sectional view showing a work locating step of the grinding machine.

FIG. 5 is a front view of the work drive device during locating.

[Explanation of symbols]

1. headstock, 2. center, 3. tailstock, 4. center, 5. work drive device, 6. grinding wheel, 7.
Spindle, 8 drive disk, 9 chuck body, 12
Oscillator, 18 floating unit, 20 claw holder, 23 gripping claw, 27 guide rod, 29
..Coil springs, 32.Fluid pressure cylinders, 35
··· Shifter, 43 ·· Work locator, 47 ·· Notch, W ··· Work.

Claims (3)

[Claims] An apparatus for gripping and rotating a work supported between a pair of centers, comprising: a chuck body rotated around one center; and a center located at a position symmetrical to an axis of the center of the chuck body. A pair of oscillating members supported so as to be able to oscillate in a plane including the axis of, a claw holder which is opened and closed in conjunction with each oscillating member, a gripping claw attached to each claw holder, and a center of the claw holder. A guide member for guiding in a plane perpendicular to the axis, a spring member provided between the guide member and the claw holder for urging the gripper in the closing direction, and means for driving the rocking body in the opening direction of the gripper; Work drive device consisting of 2. The work drive according to claim 1, wherein said driving means includes an annular member engaged with the pair of swinging members outside the claw holder, and a fluid pressure cylinder driving the annular member in a center axis direction. apparatus. 3. The work drive device according to claim 2, wherein a cutout portion through which a work locator enters and exits is provided in a part of the annular member.