JPS6315082B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a center support device for supporting one end of a workpiece in a lathe in which the headstock moves along with the main spindle in its axial direction.

Conventionally, in the above type of NC lathe, the center that supports the other end of the workpiece with one end fixed to the main spindle is slidably supported in the axial direction on a center stand fixed on the bed of the lathe, and is supported by an air cylinder or the like. Thrust force was applied to the workpiece using a weight or the like. In these devices, the center must support the workpiece at the center and slide within the center stand in conjunction with the movement of the spindle and the workpiece, so the thrust force that the center has to support the workpiece is quite large.
Due to its structure, its thrust cannot be reduced. For that reason,
When processing extremely thin long products, problems such as bending of the workpiece due to the thrust of the center occurred. Further, when the center moves while being pushed by the workpiece, the center is always subjected to sliding resistance, rotational resistance, and inertial resistance of the center support system, so that rapid forwarding of the workpiece is not possible. That is, as shown in FIG. 1, when processing a round bar workpiece 1 to obtain a product having a thick body 2 at the center and thin parts 3 at both ends, as shown in FIG. After processing the thin part 3 on the right side in step 4,
The workpiece 1 is slid inside the guide bush 6 and rapidly forwarded to the right along with the center 5 to reach the state shown in Fig. 3.
It is desirable to start a new cutting with the cutting tool 7, but if you rapidly feed the workpiece 1 while pressing the center 5 with its thin part 3, there is a risk of the thin part 3 breaking or bending, so do not use the normal cutting feed. Otherwise, it cannot be played. For this reason, the conventional equipment also had the disadvantage of requiring a long processing time.

The present invention aims to solve the above-mentioned drawbacks of the conventional device, and it is possible to always support the workpiece at the center with the optimum thrust suitable for the workpiece, and also to enable rapid forwarding while keeping the thrust constant, reducing the machining time. It is an object of the present invention to provide a center support device that can be shortened.

A center support device according to the present invention includes a center that can centrally support the other end of a workpiece whose one end is supported by a spindle, a center stand that supports the center so as to be movable in the axial direction, and a center stand that supports the center in the axial direction of the spindle. a guide bar that is movably supported by the guide bar; a first clamp device that fixes the center stand to the guide bar;
a connection bar arranged parallel to the spindle axis and extending from the headstock to the center stock; means for fixing the connection bar to either the headstock or the center stock; and means for fixing the connection bar to either the headstock or the center stock; and a second clamp device fixed to the other side of the clamp device.

Hereinafter, the present invention will be explained in more detail using embodiments of the present invention shown in FIGS. 4 to 6.

FIG. 4 is a longitudinal cross-sectional view of a main part of a moving headstock type NC lathe equipped with the center support device 10 of the present invention. In the figure, the headstock 12 (only one part is shown) that rotatably holds the spindle 11 is attached to the bed 13.
It is held in a part (not shown) of the main shaft so as to be slidable in the axial direction of the main shaft, and is moved by a ball screw (not shown). A guide bush 14 is disposed on the same axis in front of the main shaft 11, and the guide bush 14 is fitted into a guide bush support 15.
is fixed to the bed 13. The guide bush 14 slidably supports the workpiece 1 supported on the main shaft 11. A tool rest 16 is further provided on the bed 13 so as to be slidable in a direction perpendicular to the main shaft. Although not shown, a turret is provided on the tool rest 16, and a tool attached to the turret is provided near the right side of the guide bush 14 to machine the workpiece 1. Since these are known structures, detailed explanations will be omitted.

The center support device 10 has a center stand 21 equipped with a center 20 that supports the edge of the workpiece 1. The center stand 21 is connected to the center 2 as shown in detail in FIG.
The center quill 22 is supported within the center quill 22, and the center 20 is held movably in the axial direction. The rear part of the center quill 22 and the inner surface of the center stand 20 constitute a hydraulic cylinder 23, and the center quill 22 reciprocates due to the hydraulic force. A compression coil spring 24 is disposed between the center quill 22 and the center 20 and pushes the center 20 in a direction to protrude from the quill 22. Therefore, the center 20 is normally at the most protruding position from the quill 22, as shown in FIG. 5, and can be retracted into the quill by pushing the center 20 to the right.

Referring again to FIG. 4, the center stand 21 is slidably held by two guide bars 25, 26. These guide bars 25 and 26 are connected to the bed 1.
It is fixed to a frame 27 fixed to 3,
It is parallel to the axial direction of the main shaft 11, and therefore parallel to the axes of the center 20 and the center quill 22.
Thus, the center stand 21 is connected to the main shaft 11 and the center 2.
It is movable in the direction of the zero axis. Guide bar 26
A connecting bar 28 parallel to the axis of the main shaft is further disposed below the axis so as to be movable in the axial direction. The left end of the connecting bar 28 is fixed to a bracket 29 fixed to the headstock 12 using a nut 30.
The connecting bar 28 therefore moves together with the headstock 12. On the other hand, the right end of the connecting bar 28 extends to the center stand 21 and is slidably held by the center stand 21. The center stand 21 further includes a first clamp device 31 for fixing the center stand 21 to the guide bar 26, and a connecting bar 28 for fixing the center stand 21 to the guide bar 26.
It supports a second clamp device 32 that is fixed to.

As shown in detail in FIG. 6, the center stand 21 is a center stand main body 2 that holds the center and center quill.
1A, a first block 21B that supports the center stand main body 21A, and a second block 21C fixed to the first block 21B. A bearing is provided at the rear) to slidably support the guide bars 25, 26 and the connecting bar 28. The first clamp device 31 has a clamp cylinder 33 fixed to the second block 21C and a clamp piece 34 held at the tip of its piston rod, and the second clamp device 32 also has a clamp cylinder 35 fixed to the second block 21C and a clamp piece 34 held at the tip of its piston rod. It has a clamp piece 36 held at the tip of the piston rod. Each clamp cylinder of the first and second clamp devices
Controlled by an NC control panel (not shown).

Next, the cutting operation by the lathe having the above structure will be explained.

During normal cutting without center support processing, the clamp piece 3 of the first clamp device 31 is
4 moves forward and clamps the guide bar 26, and the center stand 21 is fixed to the guide bar 26 and stopped. On the other hand, the clamping piece 36 of the second clamp device 32 is separated from the connecting bar 28, so that the connecting bar 28 can freely slide relative to the center base 21. Thus, the spindle 11 is the workpiece 1
is held and rotated forward (moves to the right in Figure 4) to perform cutting. At this time, the connecting bar 28 also moves to the right in Figure 4 in conjunction with the advancement of the main shaft 11, but the connecting bar 28 moves to the right in Figure 4. Since the bar 28 is slidable relative to the center stand 21, there is no problem.

Next, to support the workpiece at the center, as described above, the center stand 21 is fixed to the guide bar 26 by the first clamp device 31, and the center table 21 is fixed to the guide bar 26 by the second clamp device 32.
is in the released state and the center quill 22 is in the retracted state, and the workpiece 1 is advanced by the main shaft 11. When the tip of the workpiece 1 (the right end in FIG. 4) reaches a predetermined position relative to the center stand 21, the headstock 12 stops moving forward. Here, the above-mentioned predetermined position is a position where the center quill 22 can advance several mm after the tip of the center 20 contacts and supports the workpiece 1 when the center quill 22 is advanced from the center stand 21 by hydraulic pressure. It is. After stopping the headstock 12, the center quill 22 is hydraulically advanced to support the workpiece 1 at the center 20. Therefore, the workpiece 1 is supported by the center 20 which receives thrust from the compression coil spring 24. After that, the second clamping device 32 is operated to clamp the connecting bar 28 with the clamp piece 36, and the center stand 28 is clamped.
1 to the connecting bar 28, and the first clamping device 31 is released so that the center stand 21 can freely slide relative to the guide bars 25, 26. With this, the center support operation is completed. Thereafter, with the workpiece 1 supported by the spindle 11 and the center 20, the headstock 12 moves forward and cutting is performed. At this time, the center stock 21 is connected to the headstock 12 via a connecting bar 28 and moves in conjunction with the headstock 12, so the thrust force of the center 20 against the workpiece is always constant regardless of the moving speed of the headstock 12. It is. Further, since the center 20 is not pushed into the center stand 21 as the workpiece moves, there is no problem even if the thrust force applied to the center 20 is small.

As described above, the thrust force of the center 20 is determined by the compression coil spring 24. Therefore, by replacing this coil spring, any desired center thrust force can be obtained and the force remains unchanged throughout the center support. Alternatively, an arbitrary center thrust may be obtained by changing the protruding length of the workpiece (material feeding length) without replacing the coil spring 24.

In the above embodiment, the connecting bar 28 is always fixed to the headstock 12, and fixed to the center block 21 by the second clamp device 32, or slidably released, but instead of this, Headstock 1
2, and the connecting bar 28 may be fixed to the center stand 21 at all times.

As described above, in the present invention, since the headstock and the center stock move in conjunction with each other, the thrust force of the center on the workpiece can be set to a small value appropriate for the workpiece, and moreover, the headstock and the center stock move in conjunction with each other. It does not change even when moving. Therefore, the workpiece is not bent by the thrust of the center, and rapid feeding is possible without any problem, which has the advantage of significantly improving cutting efficiency.

[Brief explanation of the drawing]

Figure 1 is a side view showing an example of the workpiece, Figure 2 is
FIG. 3 is a schematic side view showing the processing procedure for the workpiece shown in FIG. 1, and FIG.
A vertical cross-sectional view of the main parts of the NC lathe, Figure 5 shows the center stand 2
A partial cross-sectional side view of the main part of 1, Fig. 6 is A of Fig. 4.
-A cross-sectional view. 1... Workpiece, 10... Center support device, 11
...Spindle, 12 ... Headstock, 13 ... Bed, 1
4...Guide button, 20...Center, 21...
... Center stand, 22 ... Center quill, 24 ... Coil spring, 25, 26 ... Guide bar, 28 ...
Connection bar, 31... First clamp device, 32...
Second clamp device.

Claims (1)

[Claims] 1. In a lathe of a type in which the headstock moves in the direction of the spindle axis, a center that can centrally support the other end of a workpiece whose one end is supported by the spindle, a center stand that supports the center movably in the axial direction, and a guide bar that supports the center stand movably in the direction of the spindle axis; a first clamp device that fixes the center stand to the guide bar; and a connecting bar that is arranged parallel to the spindle axis and extends from the head spindle to the center stand. A main spindle comprising: a means for fixing the connecting bar to either one of the headstock or the center stand; and a second clamp device for fixing the connecting bar to the other of the headstock or the center stand. Center support device for moving table lathes.