JPH10193202A - Tail stock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To concurrently provide both a center support function and chuck clamp function by a single set. SOLUTION: In a tail stock 5, a static pressure shaft 31 provided with a chuck 38 in the tip end is inserted in a housing 33, static pressure radial bearings 32a, 32b rotatably supporting the static pressure shaft 31 are provided in the housing 33. In the case of center supporting a long workpiece 12 worked between itself and a head stock 3, a handle 41 is operated a rotation preventing key 46 is fitted in a rotation preventing key groove 47 formed in a shoulder part of the static pressure shaft 31, rotation of the static pressure shaft 31 is inhibited, a pre-load adjusting bolt 37 is turned to adjust a pre-load applied to the long-scaled workpiece 12 interposed between centers 11, 39. On the other hand, in the case of clamping a chuck workpiece by the chuck 38 worked, the handle 41 is operated, a rack 44 secured with a pre-load ring 35 is moved to the rear end of an opening part 33a, to be fixed by a stopper 40, the static pressure shaft 31 is made movable in the axial direction in a prescribed range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tailstock used for a machine tool such as a cylindrical grinder or a lathe for machining a long work.

[0002]

2. Description of the Related Art Conventionally, in a machine tool such as a cylindrical grinding machine or a lathe, a tailstock is provided at a position facing a headstock in order to support and process a long work at both ends thereof.

[0003] Center holes are formed in advance at the rotation centers of both end faces of the long work, and the long work is mounted between the center of the headstock and the tailstock, and preload is applied from the center of the tailstock. Work is held by holding a long work.

As described above, when machining a work supported between both centers, the rotational accuracy of the work is substantially determined by the machining accuracy of the center hole and the center formed in the end face of each work. In some cases, it has been difficult to obtain a desired processing accuracy.

In addition, since the work is supported in a small contact area between the center tip and the center hole, it is difficult to obtain sufficient rigidity against the cutting force.

Further, when a long work is supported at the center, since a preload is applied between the centers, there is a possibility that the long work is deformed, which causes a reduction in machining accuracy. .

On the other hand, in order to avoid these problems, a sub-spindle having a chuck attached separately from the tailstock is provided, and the work is selectively used according to the type of the work, such as supporting the work at the center or holding the work with the chuck. Had been

[0008]

However, in the above-mentioned conventional example, when the work is changed from the center support to the chuck holding, it is necessary to remove the tailstock from the bed and re-install the sub spindle.

In addition, since the sub spindle uses a rolling bearing to support the main shaft, it is necessary to separately provide a feed slide in order to apply a preload in the axial direction to the work held by the chuck.

As described above, when the sub-spindle on which the chuck is mounted is provided separately from the tailstock, and the sub-spindle is properly used according to the type of the work, many auxiliary operations are required.

Accordingly, an object of the present invention is to provide a tailstock that can have both a center supporting function and a chuck holding function by one unit.

[0012]

To achieve the above object, a tailstock according to the first aspect of the present invention is provided at a position facing a headstock, and a work to be machined is mounted on the headstock. In a tailstock supporting the center between the two, a chuck capable of gripping the work and the center is provided with a static pressure shaft provided at the shaft end inserted into the housing, and the static pressure shaft is rotatable and slidable. A static pressure bearing for supporting the workpiece is provided inside the housing, a preload mechanism for preloading the static pressure shaft toward the headstock is operably provided from outside the housing, and the workpiece is centered by the center gripped by the chuck. In the case of supporting, the static pressure shaft is preloaded, and when the work is gripped by the chuck, the static pressure shaft is not preloaded.

According to the present invention, when a workpiece is machined by the chuck, the workpiece provided between the headstock and the headstock is gripped by the chuck while the preload mechanism is not operated and the static pressure shaft is not preloaded. When machining a workpiece, the preload mechanism is operated to preload the static pressure shaft, and the work provided between the headstock and the headstock is supported by the center held by the chuck.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a tailstock according to the present invention will be described. The tailstock of the present embodiment is applied to a cylindrical grinding machine. FIG. 1 is a cross-sectional view showing a structure of a tailstock in which a long work is center-supported between a headstock and a tailstock as viewed from the plane. The cylindrical grinding machine 1 comprises a spindle 1 on which a center 11 is mounted.
A headstock 3 that rotatably supports the headstock 3, a tailstock 5 provided at a position facing the headstock 3, and a grinding wheel head to which a grinding wheel 18 that grinds the center-supported work 12 is attached (FIG. (Not shown) is installed on the bed.

The tailstock 5 has a static pressure shaft 31 inserted into a housing 33, and a chuck 38 is attached to a shaft end of the static pressure shaft 31 on the main shaft side. In a housing 33 through which the static pressure shaft 31 is inserted, a pair of static pressure radial bearings 32a, 3
2b are formed, and the hydrostatic radial bearings 32a, 32
The working fluid is constantly supplied to b, and the bearing function is maintained. The hydrostatic radial bearings 32a and 32b are the hydrostatic shaft 3
1 to ensure a good alignment function and a large load capacity.

An intermediate portion 31a of the hydrostatic shaft 31 having a small diameter is located between the pair of static pressure radial bearings 32a and 32b. The intermediate portion 31a has a preload contacting the step portion 31b. A precompression mechanism for urging the static pressure shaft 31 toward the headstock by integrally forming a ring 35, a precompression spring 34 for urging the precompression ring 35 toward the main shaft 13, and a precompression ring 36 to which the precompression spring 34 is fixed is formed by a housing 33. And it is loosely fitted to the static pressure shaft 31 with a gap.

Behind the preload ring 36, a housing 33 is provided.
A preload adjusting bolt 37, which is screwed through the shaft in the axial direction, is always in contact, and regulates the rear end position of the preload mechanism. By turning the preload adjusting bolt 37 to smoothly move the preload ring 35 in the axial direction, it is possible to adjust the amount of preload applied to the static pressure shaft 31 in proportion to the amount of movement.

A rack 44 to which a preload ring 35 is fixed is slidably provided in an opening 33a formed in the housing 33. On a surface on the opposite side of the rack 44, a handle 41 engraved with a binion to be screwed with the rack 44.
Is provided outside the housing 33, and the handle 41
By rotating the rack 44, the rack 44 can be moved in the axial direction to adjust the position of the front end of the preload mechanism.

As described above, by rotating the handle 41 and moving the rack 44, the preload ring 35 can be brought into contact with or separated from the step portion 31b of the static pressure shaft 31. The operation of the rack 44
Also, rapid movement of the preload ring 35 is suppressed.

Further, a through hole 44 is provided at a rear portion of the rack 44.
a is formed, and a hole 33c is formed in the surface of the housing 33 on which the rack 44 slides. When the handle 41 is rotated to move the rack 44 to the rear end, the through-holes 44 a and the holes 33 c coincide with each other, and the stopper 40 is inserted so that the preload ring 35 is moved to the step 31 of the static pressure shaft 31.
It can be fixed in a state separated from b.

A rotation prevention key 46 is fixed to the front surface of the preload ring 35, while the shoulder 3 of the static pressure shaft 31 is fixed.
A plurality of anti-rotation key grooves 47 into which the anti-rotation key 46 is inserted are formed in 1d. When the work is supported at the center, the rotation of the static pressure shaft 31 is prohibited by inserting the rotation prevention key 46 into the rotation prevention key groove 47.

Further, a magnet 45 is mounted on the front surface of the preload ring 35, and the magnet 45 is attached to the shoulder 31d of the static pressure shaft 31 so that the preload ring 35 is kept in contact with the step 31b. In this way, by temporarily connecting the static pressure shaft 31 and the preload ring 35 with the magnet 45, the static pressure shaft 31 can be easily retracted by operating the handle 41, and the work can be easily attached and detached.

The static pressure shaft 31 and the preload ring 35 may be temporarily connected using a ball catch or the like instead of the magnet 45.

Alternatively, a spline or the like may be provided on the preload ring 35 instead of the rotation prevention key 46 to inhibit the rotation of the static pressure shaft 31.

Further, in the present embodiment, the center 39 gripped by the chuck 38 has a structure in which the center tip portion 39a can freely rotate with respect to the base 39b.
The center tip may be fixed to the base.

Next, the operation of the tailstock having the above structure will be described. First, the long work 12 shown in FIG.
In the case of processing while supporting the center, the tailstock 5 is moved to a position corresponding to the length of the long work 12 and fixed to the bed. Further, a chuck 3 provided at the shaft end of the static pressure shaft 31 is provided.
8 causes the center 39 to be gripped.

Then, the stopper 40 of the rack 44 fixing the preload ring 35 at the separated position is opened, the handle 41 is operated to advance the rack 44 along the opening 33a, and the step portion of the static pressure shaft 31 is moved. The static pressure shaft 31 is preloaded by bringing the preload ring 35 into contact with the preload ring 31b, and the rotation prevention key 46 is fitted into the rotation prevention key groove 47 formed in the shoulder 31d to inhibit the rotation of the static pressure shaft 31. .

Further, by turning the preload adjusting bolt 37, the preload ring 36 is once adjusted to a position where the urging force of the preload spring 34 becomes low, and then the preload applied to the long work 12 sandwiched between the centers 11 and 39 is adjusted. adjust.

When the spindle 13 is driven on the headstock 3 side to rotate the long work 12, the tail end 5a has a structure in which the center tip 39a can freely rotate with respect to the base 39b. Long work 12 and center tip 39a
And rotate together. In the case where the center tip is fixed to the base, the long work comes into sliding contact between the center hole formed in the end face and the center.

Thus, when the long work 12 rotates,
Grinding is performed by the grinding wheel 18 provided on the grinding wheel headstock moving in the traverse direction while cutting into the long workpiece 12.

Next, a case of processing a chuck work will be described. FIG. 2 is a cross-sectional view showing the structure of the tailstock that grips the chuck work as viewed from the plane. In advance, spindle 1
3 is equipped with a chuck 15 instead of the center 11,
The center 39 is removed from the chuck 38 of the tailstock 5.

Then, the tailstock 5 is moved to a position corresponding to the length of the work and fixed to the bed. Also, handle 4
1 is operated to move the rack 44 to which the preload ring 35 is fixed to the rear end of the opening 33a and fix it with the stopper 40. Thus, the preload mechanism is completely separated from the static pressure shaft 31. As a result, the static pressure shaft 31 is freely movable in the axial direction within a predetermined range.

Then, the chuck 15 on the headstock 3 side and the chuck 38 on the tailstock 5 grip the end face of each chuck work 19, and drive the spindle 13 to drive both chucks 15, 3.
The chuck work 19 gripped by 8 is rotated. The axial position of the hydrostatic shaft 31 provided with the chuck 38 is freely determined by the main shaft 13 and rotates with the rotation of the main shaft 15.

The chuck work 19 held by the two chucks 15 and 38 rotates, and the grinding wheel 18 moves the chuck work 1.
Grinding is performed by moving in the traverse direction while cutting into 9.

As described above, in the tailstock of the present embodiment,
A hydrostatic radial bearing 3 that allows the hydrostatic shaft 31 to move in the axial direction while ensuring a good centering function and a large load capacity.
2a and 32b, the chuck work 1
When machining the long work 12, the chuck work 19 is gripped by the chuck 38 without rotating the static pressure shaft 31 without preloading, and when the long work 12 is machined, the static pressure shaft 31 is processed.
Since the long work 12 is supported by the center 39 gripped by the chuck 38 because the
The table can have both the center support function and the chuck holding function.

In this embodiment, the tailstock is applied to a cylindrical grinding machine, but the same effect can be obtained by applying the tailstock to a lathe.

In the present embodiment, a preload spring is used as the preload mechanism, but an air cylinder or the like may be used instead of the preload spring.

[0038]

According to the tailstock according to the first aspect of the present invention, when machining a chuck work, the tailstock is provided between the headstock and the static pressure shaft in a state in which the static pressure shaft is not preloaded without operating the preload mechanism. When a long work is processed while holding the held work with the chuck, the preload mechanism is operated to preload the static pressure shaft, and the work provided between the headstock and the center is held by the chuck. Therefore, a single unit can have both the center support function and the chuck holding function.

Therefore, it is not necessary to separately provide a feed slide as in the prior art, and when changing the method of supporting the work, many auxiliary operations such as re-installing the tailstock or the sub-spindle on the bed can be omitted. it can.

As described above, by employing the hydrostatic bearing, it is possible to move the hydrostatic shaft in the axial direction while securing a good centering function and a large load capacity, and to apply a preload to the hydrostatic shaft. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a tailstock in which a long work is center-supported between a headstock and a tailstock as viewed from a plane.

FIG. 2 is a cross-sectional view illustrating a structure of a tailstock that grips a chuck work as viewed from a plane.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical grinder 3 Headstock 5 Tailstock 11, 39 Center 15, 38 Chuck 32a, 32b Static pressure radial bearing 34 Preload spring 35, 36 Preload ring 37 Preload adjustment bolt 41 Handle 44 Rack 46 Rotation prevention key 47 Rotation prevention key groove

Claims (1)

[Claims] 1. A tailstock provided at a position facing a headstock and supporting a work to be processed at a center between the headstock and a chuck capable of gripping the work and the center is provided at a shaft end. A static pressure shaft is provided inside the housing, a static pressure bearing for rotatably and slidably supporting the static pressure shaft is provided inside the housing, and a preload for preloading the static pressure shaft toward the headstock side. A mechanism is operably provided from outside of the housing. When the work is center-supported by the center gripped by the chuck, the static pressure shaft is preloaded, while when the work is gripped by the chuck, the static pressure is set. A tailstock characterized by not preloading the shaft.