JPH08174307A - Spring pressure thrust mechanism in tail stock - Google Patents

Abstract

PURPOSE: To obtain optimal thrust in a wide range of works without replacing springs, by disposing spring pressure adjusting axis movable in axial direction in which compression springs of different spring contracts are placed in series in central hole of a tail spindle, and compression the compression springs in advance, thereby obtaining desired thrust. CONSTITUTION: In the case of a relatively thin in diameter, light, work W, a spring pressure adjusting screw 11 is adjusted to be in the vicinity of its retreat end so that the work W is supported with a distance being available for a first compression spring 8 protruding from a cylinder 7, and so the work V is supported with a center 7 for starting the machining. Then, in the case of a thick in diameter, heavy, work V, the pressure adjusting screw 11 is tightened until the distance becomes zero. After thus confirming that the first compression spring 8 is now contained within the cylinder 7., the spring pressure adjusting screw 11 is further tightened, so that a second compression spring 9 of higher spring contact is compressed in advance until desired thrust is obtained. Then, the work W is supported with the center 6 and machining is started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring type thrust mechanism for a tailstock used in a machine tool such as a grinding machine.

[0002]

2. Description of the Related Art Conventionally, a tailstock used for a grinder or the like uses a spring force applied to the tailstock shaft in order to slightly move the tailstock shaft in the axial direction in response to axial thermal displacement during machining of a workpiece. Most of the formats obtained by This spring-loaded tailstock is, for example, as shown in FIG. 5, fitted into a tailstock main body 101 so as to be movable in the axial direction and having a center 103 at its tip.
The compression spring 104 is fitted in the central hole 102a of
The tailstock body has a hydraulic cylinder 1 for attaching and detaching the work on the rear end surface.
05 is attached concentrically with the tailstock shaft 102.

A piston rod 1 integrated with the piston
06 is engaged with a hole of a plate 108 fixed to the rear end face of the tailstock shaft 102 so as to be movable in the axial direction by a predetermined amount, and a spring pressure adjusting screw 107 is screwed in a central hole of the piston rod 106 so as to be movable in the axial direction. The amount of bending of the compression spring 104 is adjusted by axially moving the spring pressure adjusting screw to obtain a desired thrust.

[0004]

When the spring-loaded tailstock described in the prior art is used in a machine having a large maximum work supporting weight, a spring having a high spring constant is inevitable in order to obtain a wide thrust in a limited spring chamber. Will be used. Therefore, there is a problem that it is difficult to set a low thrust with a spring having a high spring constant.

For this reason, there is a method of preparing a plurality of springs having different spring constants and exchanging them according to the purpose, but this requires a spring exchanging time and is extremely inefficient, so that productivity of a universal grinder does not pose a problem. The current situation is that it has not been put to practical use except for some models.

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 provide a tailstock capable of obtaining an optimum thrust for a wide range of works without replacing a spring. To provide a spring type thrust mechanism.

[0007]

In order to achieve the above object, a spring pressure type thrust mechanism of a tailstock according to the present invention is a thrust force by a spring pressure of a tailstock shaft which is axially movable and inserted into a tailstock body. A first compression spring having a mechanism in which a bending amount is restricted by being inserted into a cylinder having an inner peripheral flange so that one end projects, and a second compression spring having a higher spring constant than the first compression spring. Is provided in series in the center hole of the tailstock shaft, and an axially movable spring pressure adjusting shaft that obtains a desired thrust by previously compressing the first compression spring and the second compression spring is provided. The thrust constant switches between high and low at the time when the compression spring 1 is stored in the cylinder.

A thrust mechanism by spring pressure of a tailstock shaft that is fitted in the tailstock body so as to be movable in the axial direction, wherein the third compression spring has a spring constant higher than that of the third compression spring, and has a short free length. A four compression spring is provided concentrically and in parallel in the center hole of the tailstock shaft, and the third compression spring and the fourth spring are pre-compressed to obtain a desired thrust. The thrust constant is switched between high and low at a time point when the compression length of the third compression spring becomes equal to the free length of the fourth compression spring.

[0009]

According to claim 1, in the case of a work having a small diameter and light weight,
Within the adjustment range until the first compression spring is housed in the cylinder, the thrust is adjusted by moving the spring pressure adjustment shaft in the axial direction, and in the case of a large and heavy workpiece, the first compression spring is housed in the cylinder. In the adjustment range after the adjustment, the thrust is adjusted by moving the spring pressure adjusting shaft in the axial direction.

According to a second aspect of the present invention, in the case of a work having a small diameter and a light weight, the spring pressure adjusting shaft is moved in the axial direction within the adjustment range until the compression length of the third compression spring becomes equal to the free length of the fourth compression spring. When the workpiece is thick and heavy, the thrust is adjusted by using the axial movement of the spring pressure adjustment shaft within the adjustment range after the compression length of the third compression spring and the free length of the fourth compression spring become equal. Adjust thrust.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment In the tailstock for a grinding machine of FIG. 1, the tailstock shaft 2 is axially arranged in a hole 1a (not shown) formed in a tailstock body 1 (hereinafter referred to as a body) in the spindle axis direction. Only movably inserted. The center hole of the tailstock shaft 2 has a tip end formed in a tapered hole 2a, and a center 6 is detachably fitted in the tapered hole 2a. Further, the center hole of the tailstock shaft is formed with a large diameter hole 2b for the spring chamber at the rear end portion thereof, and the tapered hole 2a and the large diameter hole 2b
Is formed in the inner peripheral flange portion 2c.

A fluid pressure cylinder 3 for hydraulic or pneumatic pressure is fixed to the rear end surface 1b of the main body 1 concentrically with the tailstock shaft 2.
An outer peripheral groove 4b formed at the tip of a piston rod 4 integral with the piston 4a is engaged with a hole concentric with the tailstock shaft 2 of a plate 5 fixed to the rear end face 2d of the tailstock shaft 2 so as to be axially movable. The tailstock shaft 2 is free to move in the axial direction irrespective of the position of the piston rod 4 by the difference in the width between the plate 5 and the outer peripheral groove 4b. The work piece W is attached and detached by axially moving the tailstock shaft 2 by switching the fluid pressure to the fluid pressure cylinder 3.

A first compression spring 8 is inserted into the large-diameter hole 2a of the tailstock 2, and the first compression spring 8 has a large-diameter hole 2b.
The first compression spring 8 is set so as to protrude from the cylinder 7 by a distance L in free length, which is fitted in the cylinder 7 having an inner peripheral flange 7a that is inserted so as to be movable in the axial direction.

Further, a second compression spring 9 having a higher spring constant than the first compression spring 8 is fitted in the large diameter hole 2b so as to come into contact with the rear end face of the flange portion of the cylinder 7, and the second compression spring 9 The rear end face is in contact with the tip of the spring pressure adjusting shaft 11 which is screwed into the central hole of the piston rod 4 so as to be axially movable.

Therefore, in the process of sequentially tightening the spring pressure adjusting shaft 11 from the retracted end position, the cylinder 7 is moved to the tailstock shaft 2.
It is a spring constant obtained by combining the first compression spring 8 and the second compression spring 9 in series until the first compression spring 8 is housed in the cylinder by coming into contact with the end face of the inner peripheral flange portion 2c of the center hole, and more. When the spring pressure adjusting screw 11 is tightened, the second compression spring 9
It is the spring constant of a single unit.

To explain this in more detail, the spring constant of the first compression spring 8 is K ₁ , and the spring constant of the first compression spring 9 is K.
₂ , provided that K ₁ > K ₂ and L ₁ > 0, the combined spring constant K ₃ can be obtained by the following equation.

K ₃ = (K ₁ · K ₂ ) / (K ₁ + K ₂ ) Therefore, K ₃ becomes a value lower than K ₂ . When L ₁ = 0, the spring constant becomes K ₁ as described above. FIG. 2 is a graph showing the relationship between the deflection and the load.

Next, the first operation of the embodiment will be described. When the work W has a relatively small diameter and is light, the spring pressure adjusting screw 11 is provided so that the work W can be supported in the state where the distance L ₁ exists.
The workpiece W by the center 6
Supporting and starting processing.

When the workpiece W has a large diameter and is heavy, first the spring pressure adjusting screw 11 is used until the distance L ₁ becomes zero.
After confirming that the first compression spring 8 is housed in the cylinder 7, the spring pressure adjusting screw 11 is further tightened and the second compression spring 9 is preliminarily until a desired thrust (load) is obtained. After being compressed, the center W supports the work W to start processing.

As a result, in the case of a work having a small diameter and light weight, it is easy to set a low thrust due to the low spring constant K ₃ by the series combination of the first compression spring 8 and the compression spring 9, and in the case of a thick and heavy work. , It is easy to set a high load due to the high spring constant K ₂ of the second compression spring 9.

Embodiment 2 The difference between the first embodiment and the second embodiment is only the combination of the springs fitted in the large diameter portion 2b of the center hole of the tailstock shaft 2, and the other is the same and the same. The same reference numerals are omitted for the parts, and the description will be omitted or simply performed.

In the tailstock for a grinding machine shown in FIG. 3, a small diameter third compression spring 18 (hereinafter referred to as a small diameter spring) and a large diameter fourth compression spring are provided in the large diameter portion 2b of the central hole of the tailstock shaft 2. 19 (hereinafter referred to as a large-diameter spring) are provided concentrically and in parallel, and the large-diameter spring 19 is set to have a free length shorter than the small-diameter spring 18 by L.

Therefore, both ends of the small diameter spring 18 are in contact with the tip end surface of the spring pressure adjusting shaft 11 and the end surface of the inner peripheral flange portion 2c of the tailstock shaft 2 at the retracted end position. Has a gap of distance L ₂ . Therefore, when the spring pressure adjusting shaft 11 is successively tightened from the retracted end position, the spring constant of the small diameter spring is initially set, but when tightened for a distance L or more, the large diameter spring 19 and the small diameter spring 17 are arranged in parallel. It is the combined spring constant.

Explaining this in more detail, the large diameter spring 1
The spring constant of 9 is K ₄ , the spring constant of the small diameter spring 18 is K ₅ ,
However, when K ₄ > K ₅ and L ₂ > 0, the spring constant of the small diameter spring 18 is K ₅ as described above. Further, the combined spring constant K ₆ when L ₂ = 0 can be obtained by the following equation. K ₆ = K ₄ + K ₅ , therefore K ₆ is higher than K ₅ . FIG. 4 is a graph showing the relationship between the deflection and the load.

Next, the operation of the second embodiment will be described. When the work W has a small diameter and is light, the spring pressure adjusting screw 1 is provided so that the work W can be supported in the state where the distance L2 exists.
1 is adjusted to a position near the retracted end, and the center W supports the work W to start machining.

When the workpiece W has a large diameter and is heavy, the spring pressure adjusting shaft 11 is tightened until the distance L2 is exceeded, and it is confirmed that the large-diameter spring 9 starts to be compressed. The large-diameter spring 19 and the small-diameter spring 18 are compressed until the adjustment shaft 11 is tightened and a desired thrust (load) is obtained, and the center W supports the workpiece W to start machining. still,
The fourth compression spring 19 may have a small diameter and the third compression spring may have a large diameter, so that the outside has a long spring with a low spring constant and the inside has a short spring with a high spring constant.

In the first and second embodiments, an example in which the thrust constant is switched between high and low by combining two springs has been described, but it is also possible to combine three or more springs. In the first example, a plurality of first compression springs having different spring constants are fitted into a plurality of cylinders having different lengths, and the plurality of cylinders are fitted in the large diameter hole 2a in series or in parallel. , The thrust constant is low / medium / high or the minimum / low / medium / low at the time when a plurality of first compression springs having different spring constants are sequentially housed in the cylinder.
It is also possible to switch to a plurality of higher stages.

In the second embodiment, the small diameter spring 1 is used.
8 and a large-diameter spring 19 are concentrically provided with a medium-sized spring having a different free length and a different spring constant, or a first medium-sized spring and a second medium-sized spring.
As the spring pressure adjusting shaft 11 is tightened, first the spring constant of the small diameter spring 18 alone, then the parallel constant spring constant of the small diameter spring 18 and the medium diameter spring or the first medium diameter spring, and finally the parallelization of all springs. It is also possible to switch the thrust constant as three or more steps as the combined spring constant, and by doing so, a combined spring constant closer to the ideal can be obtained.

[0029]

Since the present invention is configured as described above, it has the following effects. Claim 1 and Claim 2
Both as a thrusting mechanism of the tailstock shaft incorporating multiple springs,
Since it is possible to switch between heavy work and light work depending on the axial position of the spring pressure adjustment shaft, it is possible to set the optimum thrust of the tailstock shaft for all works without replacing the spring. .

[Brief description of drawings]

FIG. 1 is a cross-sectional top view of a tailstock having a first spring pressure type thrust mechanism according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between deflection and load of two compression springs combined in series with the tailstock of FIG.

FIG. 3 is a top cross-sectional view of a tailstock having a spring pressure type thrust mechanism according to a second embodiment of the present invention.

FIG. 4 is a graph showing the relationship between deflection and load of two compression springs of the tailstock of FIG. 3 combined in parallel.

FIG. 5 is a cross-sectional top view of a tailstock having a conventional spring pressure type thrust mechanism.

[Explanation of symbols]

 1 Tailstock main body 2 Tailstock shaft 3 Fluid pressure cylinder 6 Center 7 Cylinder 8 1st compression spring 9 2nd compression spring 11 Spring pressure adjustment shaft 18 3rd compression spring (small diameter spring) 19 4th compression spring (large diameter spring) )

Claims (2)

[Claims] 1. A thrust mechanism by spring pressure of a tailstock shaft that is fitted in a tailstock body so as to be movable in an axial direction, and has one end protruding into a cylinder having an inner peripheral flange portion. A first compression spring whose deflection amount is restricted and a second compression spring having a higher spring constant than the first compression spring are provided in series in the center hole of the tailstock shaft, and the first compression spring and the second compression spring are provided. Is provided with an axially movable spring pressure adjusting shaft that obtains a desired thrust by compressing and in advance, and the thrust constant switches between high and low at the time when the first compression spring is housed in the cylinder as a boundary. Spring-loaded thrust mechanism for tailstock. 2. A thrust mechanism by spring pressure of a tailstock shaft that is inserted into a tailstock body so as to be movable in the axial direction, the third compression spring having a spring constant higher than that of the third compression spring and having a free length. A short fourth compression spring is provided concentrically and in parallel in the center hole of the tailstock shaft, and the third compression spring and the fourth spring are pre-compressed to obtain a desired thrust. A spring-loaded thrust mechanism for a tailstock, wherein a thrust constant is switched between high and low at a time point when a compression length of a third compression spring becomes equal to a free length of a fourth compression spring, which is provided with an axis.