JPH08229704A - Center pushing device - Google Patents

Abstract

PURPOSE: To shorten a processing time, prevent the damage of a work and improve a processing accuracy. CONSTITUTION: A piston 6 is provided on the rear end of at center pushing shaft 2 provided advanceably/retreatably in the center hole 1a of a tailstock main body 1 and a variable throttle valve 10 is formed by the center part 7a for the center hole of the rear end surface of an oil chamber 7 installed in the center hole 2a of the center pushing shaft 2 of a hydraulic tailstock having a cylinder 5 behind the cylindrical hole of the tailstock main body and the and surface corner part 11a of a valve rod 12 inserted in the center hole 2a of a center 11 rear end provided on the center pushing shaft movably in the axial direction. A throttle amount is getting bigger gradually as the center 11 is contacted with a work W by the advance of the center pushing shaft and the valve rod is retreated relatively and by squeezing the discharge oil amount from a front chamber 15a and raising the discharge pressure, the throttle amount reaches maximum at the point of time when the center 11 is engaged with a taper hole 4a and stopped and the deformation of a center hole Wa by an inertia force is prevented by the slow down of the advance speed of the center pushing shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulically driven tailstock used for machine tools such as lathes or grinders.

[0002]

2. Description of the Related Art Conventionally, a tailstock is used to prevent a work from being deformed by a cutting force when machining a shaft work which is longer in the axial direction than a diameter in a machine tool such as a lathe. There are automatic type such as hydraulic, pneumatic, electric etc. and manual type using a screw etc., but in both cases, the center attached to the tip of the tailing shaft is pressed against the center hole of the work and cutting force is applied. In the automatic system, the pressing speed and the pressing force are set in advance according to the shape of the work.

[0003]

The pressing speed of the tailstock shaft described in the prior art directly affects the machining time, so the faster it is, the better. However, the center comes into contact with the center hole of the work and the tailstock shaft moves. There is a problem that the center hole may be deformed due to inertial force when stopping, or the work may be deformed to be unusable in an extreme case.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to achieve both the reduction of processing time and the prevention of work deformation and device damage. The present invention is intended to provide a tailing device that can be used.

[0005]

In order to achieve the above object, a tailstock device according to the present invention is provided so as to be axially movable in a first center hole having a cylinder of a tailstock main body, and is provided near the rear end. A tailstock shaft member having a piston that is fitted in the cylinder so as to be movable in the axial direction, and a valve seat for throttling, which is provided in the middle of the second center hole of the tailstock shaft member and has a corner between the rear end surface and the center hole. And an oil chamber formed in the second end of the tailstock shaft member.
A shaft having a valve rod which is inserted into the second center hole after a taper portion which is detachably engaged with the taper hole at the tip of the center hole and whose end face corner portion forms a variable throttle valve corresponding to the valve seat. Direction, a work supporting center, a locking member for preventing protrusion of the center for restricting the forward end position of the center, an oil passage communicating with the oil chamber and the center side chamber of the cylinder, and the oil. And a means for supplying pressure oil to the chamber or a chamber on the side opposite to the center of the cylinder. When stopped, the throttle amount becomes maximum and the speed of the tailstock shaft member becomes slow.

[0006]

When the tailstock shaft moves forward to support the work, the center at the forward end position comes into contact with the center hole of the work and relatively moves backward. This retreat of the center gradually increases the throttle amount of the variable throttle valve as the end surface of the valve rod approaches the valve seat, limiting the flow rate of back oil returned from the cylinder front chamber to the external tank and increasing the exhaust pressure. Gradually reduce the forward speed of the tailstock shaft.

When the tapered portion of the center comes into contact with the tapered hole of the center hole of the tailstock shaft, the end face of the valve rod comes closest to the valve seat, the throttle amount becomes maximum, and the forward speed of the tailstock shaft slows down.
Minimize the influence of inertial force on the center hole when the tailstock is stopped.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are sectional views of a hydraulic tailstock. The tailstock main body 1 is fixed so as to be positionally movable on a guide in the direction of the main axis (Z axis) provided on a bed (not shown),
A center hole 1a and a cylinder 5 are bored in the tailstock body 1 concentrically with the spindle axis, and a piston 6 is inserted in the center hole 1a.
The tailstock shaft 2 integrally having the above is fitted and inserted so as to be able to advance and retreat in the axial direction.

A center hole 2a is formed through the tailstock shaft 2, and a rotary shaft 4 is rotatably supported by a plurality of bearings 3 at a large diameter portion at the tip of the center hole 2a. The rotating shaft 4 also has a center hole penetrating therethrough, and the tip of the center hole is formed in the tapered hole 4a.

An oil chamber 7 in the form of an inner circumferential groove is formed at a position slightly rearward of the center hole 2a of the tailstock shaft 2 and slightly in front of the piston 6, and the center hole 2a of the rear end face of the oil chamber 7 is formed. Is formed on the valve seat 7a for throttling. Rear end face 1 of tailstock body 1
A lid 8 also serving as the rear end surface of the cylinder 5 is fixed to b, and the lid 8 integrally has a protruding shaft portion 8a.
The front end of a is axially movable and airtightly fitted into the center hole 2a of the tailstock shaft 2.

An oil passage 8b penetrates through the lid 8 at the center,
The oil passage 8b communicates with the oil chamber 7 through the center hole 2a, and the rear end opening to the outside communicates with a pressure oil supply device (not shown) through the pipe 9. Further, the tailstock shaft 2 is provided with an oil passage 2b communicating with the oil chamber 7 and the front chamber 5a of the cylinder 5.

The center 11 is provided with a taper portion corresponding to the taper hole 4a, and the rear end is fitted in the center hole of the tailstock shaft 2 so as to be axially movable so that the end portion reaches the oil chamber 7. The valve stem 12 is fixed concentrically, and the variable throttle valve 10 is formed by the end face corner 12a of the valve stem 12 and the valve seat of the oil chamber 7. In the variable throttle valve 10, when the center 11 contacts the center hole Wa of the work W as the tailstock shaft 2 moves forward, the center 11 retracts in the relative direction, and the taper portion 11a abuts the taper hole 4a of the rotary shaft 4. When the advance of the tailstock shaft 2 is blocked, the end surface 12a of the valve rod 12 comes closest to the valve seat 7a, and the flow rate between the oil passages 2b and 8b is narrowed down to the minimum.

An annular stopper 13 is fixed to the tip end surface 2c of the tailstock shaft 2, and an engaging flange portion 11b integrally provided on the outer periphery of the cylindrical portion of the center 11 abuts the inside of the stopper 13. The center 11 is prevented from moving forward to prevent the center 11 from popping out. The tailstock body 1 is provided with a rear chamber 5b of the cylinder 5 and an oil passage 1c opening to the outside.
The pipe 14 communicates with a pressure oil supply device (not shown).

Next, the operation of this embodiment will be described. FIG. 1 shows a state in which the tailstock shaft is being moved forward or backward, and FIG. 2 is a view that also serves as an operation view showing a state in which a work is supported.
Now, the pressure oil, which is set to a constant pressure by the regulator by the pressure oil supply device (not shown), is supplied to the oil passage 1c by the pipe 14 through the electromagnetic switching valve (not shown) and is sent to the rear chamber of the cylinder 5 so that the tailstock is pressed. The shaft 2 moves forward and the center 11 supports the work W to perform the cutting process.

After the cutting process is completed, the electromagnetic switching valve (not shown) is switched, and the pressure oil supplied to the oil passage 8b by the pipe 9 passes through the center hole 2a, the oil chamber 7, and the oil passage 2b, and the front chamber 5a of the cylinder 5 is reached. The tailstock shaft 2 starts to retreat. At this time, due to the action of the pressure oil supplied to the oil chamber 7, the valve rod 1
2. The center 11 moves forward relative to the tailstock shaft 2, the variable throttle 10 is opened as the end face corner 12a of the valve rod 12 moves away from the valve seat 7a, and the backward speed of the tailstock shaft 3 is gradually increased. . Then, the collar portion 11b of the center 11 is attached to the stopper 13
When the center 11 abuts and the relative advance is blocked, the center 11 separates from the center hole Wa of the work W and rapidly retreats.

Next, after the work W is replaced, an unillustrated electromagnetic switching valve is switched, pressure oil is sent from the pipe 14 to the rear chamber of the cylinder 5 through the oil passage 1c, and the tailstock shaft 2 moves forward. , The center 11 comes into contact with the center hole Wa of the work W to start the relative retreat. As the tailstock shaft 2 moves forward, the valve rod 12 retracts together with the center 11, and as the end face 12a of the valve rod approaches the valve seat 7a, the throttle amount by the variable throttle valve 10 gradually increases, and the front chamber 5a of the cylinder 5a.
The amount of oil returned from is limited, the back pressure is increased, and the forward speed of the tailstock shaft 2 is reduced.

The taper portion 11a of the tailstock center 11
When is engaged with the taper hole 4a of the rotary shaft 4, the maximum throttle amount is obtained, the forward speed of the tailstock shaft becomes the lowest speed, and the forward movement of the tailstock shaft 7 is stopped. Then, the center hole Wa is pressed by the force of the pressure oil supplied to the rear chamber 5b of the cylinder 5 to support the work W, and the cutting process is restarted.

[0018]

Since the present invention is configured as described above, it has the following effects. The rear end surface of the oil chamber provided in the center hole of the tailstock shaft is formed into a valve seat for throttling, and a valve rod protruding into the oil chamber at the rear end of the center is provided on the tailstock shaft so as to advance and retract in the axial direction. By the variable throttle valve consisting of the end face and the valve seat,
The throttle amount is maximized immediately before supporting the work, and the advance speed of the tailstock shaft is slowed down.Therefore, excessive force is not applied to the work and its center hole. It is possible to significantly speed up,
The processing time can be shortened and the quality of the work can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a tailstock device according to an embodiment of the present invention, showing the middle of movement of a tailstock shaft.

FIG. 2 is a sectional view of the tailing device, showing a state of supporting a work.

[Explanation of symbols]

 1 tailstock main body 1a center hole (first center hole) 1c, 2b, 8b oil passage 2 tailstock shaft 2a second center hole 4 rotary shaft 4a taper hole 5 cylinder 6 piston 7 oil chamber 7a valve seat 10 variable throttle valve 11 center 12 valve rod 12a end face corner of valve rod W work Wa center hole

Claims (1)

[Claims] 1. A first having a cylinder of a tailstock main body afterward
A tailstock shaft member having a piston movably in the center hole axially movably fitted in the cylinder near the rear end, and a tailstock shaft member provided in the middle of the second center hole of the tailstock shaft member. The oil chamber is formed at a corner of the end face and the central hole in the valve seat for throttle, and the taper portion is detachably engaged with the tapered hole at the tip of the second central hole of the tailstock shaft member. An axially advancing / retreating work support center having a valve rod that is inserted into the second center hole and has a corner portion of the end face corresponding to the valve seat to form a variable throttle valve, and a forward end position of the center is regulated. A locking member for preventing popping out, an oil passage communicating with the oil chamber and the center-side chamber of the cylinder, and means for supplying pressure oil to the oil chamber or the chamber on the opposite side of the cylinder. When the tailstock shaft moves forward, the center comes into contact with the workpiece and moves back relatively Tailstock and wherein the speed of the tailstock shaft member becomes slow so the amount and aperture stop engages the over path hole and best.