JPH0621601Y2 - Machine tool spindle structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a spindle structure of a machine tool.

(Prior Art) In a machine tool for rotating a processing tool, a main shaft is rotatably held by a bearing member via a bearing, and the processing tool is attached to the tip end of the main shaft (for example, the actual machine).
59-105334 gazette) (Problems to be solved by the invention) By the way, in this type of machine tool, due to thermal expansion due to heat generation during use, the main shaft moves to the tip side, that is, the tool mounting tool. This may cause a problem that it is displaced toward the side and adversely affects the processing accuracy.

Explaining this point in detail, although the displacement of the main shaft in the axial direction is regulated through the bearing, the position regulation of the bearing itself sets the outer race so as not to move in the axial direction with respect to the bearing member. It is done by. Then, when the outer race thermally expands, there is no problem if it is displaced to the rear side, that is, the side opposite to the tip side, but when it is displaced toward the tip side, the main shaft is also displaced to the tip side with this, It had a bad influence on the above-mentioned processing accuracy.

Therefore, an object of the present invention is to provide a spindle structure for a machine tool that prevents the spindle from being displaced toward the tip end side, which is the work tool mounting side, due to thermal expansion due to heat generation.

(Means and Actions for Solving Problems) In order to achieve the above object, the present invention has the following configuration. That is, in a spindle structure of a machine tool in which a spindle is rotatably held by a bearing member via a bearing, and a work tool is attached to a tip end portion of the spindle, in the bearing member, an axial front side of an outer race of the bearing A front stopper that abuts from the side to restrict the forward movement of the outer race is fixed, and when the bearing member comes into contact with the outer race of the bearing from the rear side and receives a large rearward external force from the outer race. A variable stopper that allows the rearward displacement of the outer race is provided, and the variable stopper includes a mounting hole formed in a radial direction of the bearing member, and a slidable fit in the mounting hole and the outer race. A stopper piece having a tapered surface that abuts against the rear end, an adjusting screw screwed into the mounting hole, and the stopper piece And a spring housed in the mounting hole so as to be interposed between the adjusting screw and the adjusting screw.

With such a configuration, the variable stopper normally functions as an ordinary stopper that comes into contact with the outer race from the rear side in the axial direction to regulate the displacement in this direction. When the heat is generated by the addition of heat, the outer race is escaped rearward by the amount of the heat expansion to prevent the main shaft from displacing to the tip side.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a bearing member, and a main shaft 6 is rotatably held by the bearing member 1 via bearings 2, 3, 4, and 5. A tool holder 7 is detachably attached to the tip portion (left end portion in the figure) of the main shaft 6,
An appropriate processing tool (not shown) can be attached to the tool holder 7. The bearings 2, 3, 4, and 5 are arranged axially in series with each other, and in the embodiment, the bearing 2 closest to the tip is of a roller type. Further, the bearing 3 behind the bearing 2 is of a ball type in which the outer race 3A and the inner race 3B cannot be displaced relative to each other in the axial direction, so that the axial length change due to thermal expansion is likely to be large. It is supposed to be. Furthermore, the two bearings 4 and 5 behind the bearing 3 are of the angular type.

Of the bearings 2 to 5, the bearings 2 and 3 are used to regulate the main shaft 6 so as not to be displaced in the axial direction. That is, the ring-shaped front stopper 8 is fixed to the front end surface of the bearing member 1 by the bolts 9, while the variable stopper 10 is provided on the bearing member 1 behind the bearing member 3 and the front stopper 8 and the variable stopper 10 are variable. With the stopper 10, the outer races 2A, 3A of the bearings 2, 3 are sandwiched without rattling in the axial direction. Also,
A spacer 11 which also serves as an oil drainer is arranged in front of the inner race 2B of the bearing 2, a spacer 12 is arranged between the inner races 2B and 3B, and a spacer 13 is arranged behind the inner race 3B of the bearing 3. Each of these elements 11, 2B, 12, 3B, 13 includes a step portion 6a formed at the front end portion of the main shaft 6 and a nut 1 screwed to the main shaft 6.
It is sandwiched between 4 and.

The variable stoppers 10 act on the outer race 3A of the bearing 3, and are provided on the main shaft 6 at intervals in the circumferential direction. In the embodiment, the variable stopper 10 is provided with the bearing member 1 as shown in FIG.
Mounting hole 2 that is formed in the main shaft 6 and penetrates in the radial direction of the main shaft 6.
1, a stopper piece 22 slidably fitted in the mounting hole 21, a spring 23 for urging the contact piece 22 toward the main shaft 6 side, and a spring 23 screwed into the mounting hole 21. And an adjusting screw 24 for adjusting the biasing force of 23.

In the stopper piece 22 of the variable stopper 10, the front end side and the rear end side in the axial direction of the main shaft 6 are tapered surfaces 22 respectively.
a and 22b, and the rear end surface of the outer race 3A of the bearing 3 is also formed as a tapered surface 3a corresponding to the tapered surface 22a. Further, in the bearing member 1, a step portion 1a having a height substantially equal to the thickness of the outer race 3A is formed behind the stopper piece 22, and the axial front end surface side of the main shaft 6 in the step portion 1a is the taper. The taper surface 1b corresponds to 22b.

In the above-described configuration, the main shaft 6 performs processing on the work by being rotated by a drive source (not shown) with the processing tool attached to the attachment head 7. At this time, the outer races 2A, 3A of the bearings 2, 3
Is held by the front stopper 8 and the variable stopper 22 without rattling in the axial direction.
The axial displacement is restricted with respect to (see FIG. 2).

Here, when the heat generation causes thermal expansion of the bearings 2 and 3 that regulate the axial displacement of the main shaft 6, the outer races 2A and 3 of the bearings 2 and 3 are thermally expanded.
The axial length of A becomes long. At this time, the lengthened outer races 2A, 3A due to this thermal expansion are absorbed by the stopper piece 22 of the variable stopper 10 retracting in the mounting hole 21 as shown in FIG. That is, each outer race 2 of the bearings 2 and 3
Due to the thermal expansion, A and 3A escape to the rear side by this thermal expansion amount without forcibly pressing and displacing the stopper 8 forward. This prevents the spindle 6 from displacing to the tip side.

It should be noted that, as in the embodiment, the step portion 1 is provided to the rear of the stopper piece 22.
If a is formed, the stepped portion 1a receives a large rearward external force from the outer race 3B side and prevents the stopper 22 from being subjected to an excessive bending force in the radial direction of the mounting hole 21. And this mounting hole 2
The rattling between 1 and the stopper piece 22 can be effectively absorbed. Further, the adjusting screw 24 allows the stopper piece 2
2 escape into the mounting hole 21 and outer race 3A
The relationship with the magnitude of the external force from the rear to can be set appropriately.

(Effect of the Invention) As is apparent from the above description, the present invention is configured to prevent the spindle from displacing to the tip side, which is the mounting side of the processing tool, when the bearing thermally expands due to heat generation. Therefore, it is possible to eliminate the thermal influence and always maintain sufficient processing accuracy.

In addition, the variable stopper receives the force when the outer race of the bearing is displaced rearward by the spring as the radial force of the main shaft using the tapered surface of the stopper piece, so an extremely large external force due to thermal expansion acts. Unless it is done, it is possible to prevent the outer race from being displaced rearward. This means that the outer race can be firmly clamped in the axial direction of the main shaft by the front stopper and the variable stopper, and as a result, there is no problem in terms of the supporting rigidity of the main shaft in the axial direction.

Further, since the spring force can be adjusted by the adjusting screw, it is possible to always solve the problem due to thermal expansion while ensuring the supporting rigidity in the axial direction.

Of course, since the variable stopper does not particularly limit the radial support structure of the main shaft, it is possible to sufficiently secure the radial support rigidity.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention. 2 and 3 are enlarged cross-sectional views of the main part of FIG. 1, FIG. 2 shows the time at low temperature, and FIG. 3 shows the time at high temperature. 1: Bearing member 3: Bearing 3A: Outer race 6: Spindle 7: Mounting head (for processing tool) 10: Variable stopper 8: Front stopper 21: Mounting hole 22: Stopper piece 23: Spring 24: Adjustment screw

Claims (1)

[Scope of utility model registration request] 1. A spindle structure of a machine tool, wherein a spindle is rotatably held by a bearing member via a bearing, and a processing tool is attached to a tip end portion of the spindle, wherein the bearing member has an outer race. A front stopper is fixed which abuts from the front side in the axial direction to restrict the forward movement of the outer race, contacts the outer race of the bearing from the rear side with the bearing member, and receives a large rearward force from the outer race. A variable stopper that allows the outer race to be displaced rearward is provided, and the variable stopper is slidably inserted into a mounting hole formed in the radial direction of the bearing member and the mounting hole. A stopper piece having a tapered surface that abuts on the rear end of the outer race, an adjusting screw screwed into the mounting hole, and the stopper. Wherein a spring housed in the mounting hole, and a main shaft structure of the machine tool, characterized in that so as to be interposed between the adjusting screw and.