JPH0224009A - Spindle for machine tool - Google Patents

Abstract

PURPOSE:To increase the stiffness of a bonding part, to prevent the vibration of a tool holder by high speed rotation and the runout of a tool axial line and to obtain a high machining accuracy by forming so that the tapered hole of a main shaft and the main shaft end face are simultaneously closely fitted to a tool holder. CONSTITUTION:A tool holder 8 has a fitting base 9 fitting a tool 7, the flange part 10 having an annular groove 10a for inserting an offtake arm, a taper shaft part 11 and clamp shaft part 12. The pull-in bar 42 to whose tip a collet 43 is fixed is inserted into the hollow hole 41 of a main shaft 13, the collet 4 is spread when pushed out, the tip of the clamp shaft part 12 can be inserted, and when pulled, the tip part is shrinked by the inner wall of the follow hole 41 and the clamp shaft part 12 is interposed. The flange face 10 is closely fitted to an end face 13a simultaneously with the holder 8 being pulled into the tapered hole 14 of the main shaft 13 and the taper shaft 11 being closely fitted to the tapered hole 14 and the bonding stiffness of the tool holder 8 and main shaft 13 is formed higher.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a spindle for a machine tool.

[Prior art]

In machine tools, such as machining centers, the tapered end of a tool holder is inserted into a tapered hole formed at the tip of a rotatably supported main shaft of a spindle, and a tapered part of the main shaft and a tapered part of the tool holder are inserted. A bonded state was formed by the close contact.

In conventional machine tool spindles like this, the taper is connected only at one part, so the rigidity of the connected part is low.
When the rotation speed of the spindle increases, vibrations occur in the tool holder and runout of the axis of the tool occurs, resulting in a problem that machining accuracy cannot be obtained in precision machining.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned conventional problems and provide a spindle for a machine tool that has high coupling rigidity with a tool holder.

[Means for Achieving the Object] The present invention solves the above problem by providing a spindle for a machine tool which is formed so that the taper hole of the main spindle and the end surface of the main spindle are simultaneously in close contact with the tool holder when the tool holder is fixed to the main spindle. Achieved by

[Function] According to the present invention, when the tool holder is attached to the main spindle and the tool holder is fixed, the taper part of the tool holder comes into close contact with the taper hole of the main spindle, and at the same time, the plunge part of the tool holder comes into close contact with the end face of the main spindle. do.

〔Example〕

The details of the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 shows an example of a cartridge spindle having a spindle casing l that is detachable from the main body of a machine tool.

This figure shows a motor-built-in type spindle in which a motor 2 is housed in a spindle casing 1.

A motor housing 3 is assembled into the spindle casing 1. The motor housing 3 is prevented from rotation and axial movement by the pin 4. Motor 2 has a stator 5 and a rotor 6.

The tool holder 8 for fixing the tool R7 includes a mounting base 9 for mounting the tool Ji7, a flange portion 10 having an annular groove 10a for inserting a take-out arm, a tapered shaft portion 11 extending from the flange portion, and a tapered shaft portion 11. The clamp shaft portion 12 is formed at the tip of the clamp shaft portion 12 .

The main shaft 13 has a tapered shaft portion 11 of the tool holder 8 at its tip.
A tapered hole 14 is formed in which the holder is mounted.

A collar 15 is formed on the outer periphery of the tip of the main shaft 13, and the first bearing 16 is inserted into the outer peripheral surface of the main shaft 13 so as to come into contact with the collar 15.

The first bearing 16 has two angular ball bearings 1
3, and an inner collar 18 inserted between the angular ball bearings 13 so as to come into contact with the inner race, and an outer collar 19 that is installed so as to come into contact with the outer race. The first bearing 16 is fixed in position to a presser collar 20 that is inserted into the main shaft 13 and fixed by shrink fitting. A set screw 21 is used when removing the retainer collar 20.

The first bearing 16 is fitted into the spindle casing 1,
It is positioned and fixed to the spindle casing l by the presser cover 22. The presser cover 22 is fixed to the spindle casing 1 with bolts 23.

A rotor mounting portion 24 formed as a tapered outer circumferential surface is formed in the middle portion of the main shaft 13, and the rotor 6 of the motor 2 is inserted into this rotor mounting portion 24.

An intermediate collar 25 and a second bearing 26 are sequentially attached to the main shaft 13 adjacent to the rotor 6, and are fixed in a pressed state by a pressing collar 27. The retainer collar 27 is fixed to 13 by shrink fitting. When removing the retainer collar 27, use the second screw.

Similar to the first bearing 16, the second bearing 26 includes two angular ball bearings 29, an inner collar 30 that is mounted between the angular ball bearings 29 so as to abut against the inner race, and an outer race. It has an outer collar 31 that is attached so as to be in contact with it.

The outer peripheral portion of the second bearing 26 is fitted into the inner race 33 of the third bearing 32 . The outer race 34 of the third bearing 32 is fitted into the spindle casing l, and is fixed to the spindle casing l by a presser cover 35 while in contact with the motor housing 3. A rear casing 36 is fixed to the spindle casing 1 via a holding cover 35.

A cylinder 37 is attached to the rear casing 36.

A spindle 38 is slidably guided in the cylinder 37, and a piston chamber 39 within the cylinder 37 is closed by a cover 40.

A hollow hole 41 is formed in the main shaft I3, and a retraction bar 42
is inserted. A collet 43 is fixed to the tip of the retraction bar 42 by a bolt 44 as is well known. colette 4
3 is pushed out to the left in FIG. 1 and its tip expands, allowing the bulge at the tip of the clamp shaft 12 of the tool holder 8 to be inserted. When the collet 43 is pulled to the right in FIG. 1, the tip of the collet is squeezed by the inner wall of the hollow hole 41 of the main shaft 13, and the bulge of the clamp shaft 12 is clamped in such a way that it cannot be pulled out. .

When the spindle 38 moves to the left in the figure, the retraction bar 42 is pushed by the piston rod 45 and moves to the left in the figure, and when the piston retreats to the right, it is pushed to the right in the figure by the disc spring 46. , the collet 43 is the tool holder 8
A sleeve 55 is screwed onto the retraction bar 42 in order to hold down the disc spring 46 that clamps and holds the clamp shaft 12 of the clamp shaft 12 .

The piston chamber 39 of the cylinder 37 is connected by channels 47 and 48 to a fluid pressure source for supplying and discharging liquid, for example compressed air. A dog 50 is fixed to the outer rod 49 of the piston 38 by a set screw 51, and a limit switch (not shown) is attached to a bracket 52.
Detects the movement of the piston.

A cooling jacket 5 is provided on the outer periphery of the tip of the spindle casing 1.
3 are fixed by bolts 4. As shown in FIG. 2, the cooling jacket 53 has a first bushing 56 and a second bushing ≦
7. The third bushier 58 is inserted and fixed at predetermined angular intervals.

Both the first bushing 56 and the second bushing 57 have narrow tips 56a, 57a that project radially into the spindle flange 1 and the outer collar 19, respectively.

The third bush 58 has a thin tip 58a extending in the radial direction so as to come into contact with the outer peripheral surface of the outer collar 19.

3 to 5, the outer collar 19 has a first through hole 5 into which the tip 56a of the first bush 56 is inserted.
9 and a second bushing into which the tip 57a of the second bushing 57 is inserted.
The through holes 60 are formed at predetermined angular intervals, for example, at 30° angular intervals.

The first through hole 59 and the second through hole 60 are connected to the outer collar 19.
are formed at positions offset from each other in opposite directions with respect to the center plane.

Guide paths 61a extend radially at predetermined angular intervals, for example, 90 degrees, from the first through hole 59, and guide channels 61b extend radially at predetermined angular intervals, for example, 90 degrees from the second through hole 60. is formed as a blind hole that is open on the outer peripheral surface of the outer collar 19 and closed on the inner peripheral surface side.

The first through hole 59 is used for hair ring lubrication on the upper side of the two angular bearings 17, that is, on the right side in the figure, and the guide path 61a is used for cooling the upper side of the two angular bearings 17, that is, on the right side in the figure. used for purposes.

The second through hole 60 is used for lubrication of the angular roller bearing 17 on the lower side, that is, on the left side in the figure, and the guide path 61b is used for cooling the angular roller bearing 17 on the lower side, that is, on the left side in the figure. used as. Therefore, the first bush 56 inserted into the first through hole 59 is used for the upper bearing, and the second bush 57 inserted into the second through hole 60 is used for the lower bearing.

The first bushing 56 and the second bushing 57 have tip portions 56
Flow channels 62 and 63 formed as closed blind holes are provided at the tips of the holes 62 and 63, respectively, and a nozzle opening 64 that opens diagonally toward the tips is formed laterally from the channels 62 and 63. (Figure 1).

At the time of assembly, the nozzle opening 64 of the first punch 56 and the nozzle opening 64 of the second bush 57 are assembled so as to face oppositely to each other. That is, the nozzle port 64 of the first bush 56
is arranged so that it faces the upper bearing 17, and the nozzle port 64 of the second bush 57 faces the lower bearing 17.

The guide path 61a of the outer collar 19 has a nozzle opening 65 that opens laterally from the inner peripheral end and diagonally toward the upper bearing 17 toward the center of the outer collar, that is, toward the inside.
a, and the guide path 61b has a nozzle opening 65 that opens diagonally inward on the lower bearing side opposite to the nozzle opening 65a.
It has b. The openings of the guide paths 61a and 61b on the outer circumferential surface of the outer collar 19 communicate with each other through an arcuate groove 66 formed on the outer circumferential surface of the outer collar 19. The nozzle port 64 is formed to spray oil and air near the contact position between the ball of the adjacent bearing and the inner race, and the nozzles 65a and 65b are formed to spray cooling gas or air near the contact position between the ball of the adjacent hair ring and the inner race. For example, it is formed to blow compressed air.

When the first bushing 56 is assembled, the flow path 62 is connected to an oil/air supply path 68 formed in the spindle casing 1 via a connection path 67 formed in the jacket 53, as shown in FIG.

A groove 66 on the outer periphery of the outer collar 19 is connected to a cooling gas supply passage 69 formed in the spindle casing 1.

During assembly, the outer collar 19 is prevented from rotating by inserting the tip of the anti-rotation pin 70 into the outer peripheral surface.

The third bushing 58 has a through hole 7 concentrically formed at the tip 58a.
1 is formed and a temperature sensor, for example a thermistor, is inserted. The third bush 58 connects the cap 72 to the cooling jacket 53.
It is fixed and held by fixing it with a bolt or the like.

The second bearing 26, like the first bearing 16, is oil-air cooled and gas-cooled (for example, air cooled).

In the case of the first bearing 16, the bushing was attached to the outer collar, whereas the outer collar 31 of the second bearing 26
Now, flow path 73 corresponding to Bush's flow ll562.63
is formed directly. A nozzle lower 4 is similarly formed in the flow path 73.

Guide path 7 corresponding to guide paths 61a and 61b in the case of the first bearing
5 is formed on the outer collar 31.

Cooling gas, such as compressed air, is supplied to the guide path 75 through a cooling gas supply path 76 formed in the inner race 33 of the third bearing 32, and the flow path 73 is supplied through an oil-air supply path 77 formed in the inner race 33. Oil air is supplied.

When the tool holder 8 is drawn into the tapered hole 14 of the main shaft 13 and the tapered shaft 11 comes into close contact with the tapered hole 14,
At the same time, the surface of the flange portion 10 of the tool holder 8
It comes into close contact with the end surface 13a of.

Since the surface of the tapered shaft 11 and the surface of the flange portion 10 are in close contact with the main shaft 13 at the same time, the rigidity of the connection between the tool holder 8 and the main shaft 13 is formed by both contact parts.

The main spindle cannot avoid heating due to motor heat etc. during machining, but the first bearing 16 is fixed in position, and the elongation due to thermal expansion of the main spindle 13 occurs between the inner race 33 and outer race 34 of the third bearing 32. Absorbed.

It is difficult to bring two surfaces into close contact with the workpiece at the same time, such as the taper surface and flange surface of a tool holder, in terms of machining accuracy. It is now possible to clamp the tool holder to the spindle on both the plunge surface and the plunge surface.

〔effect〕

The present invention makes it possible to clamp the tool holder closely to the main shaft at the taper shaft and flange surface,
A more rigid connection can now be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a spindle of a machine tool according to the present invention;
Figure 2 is a sectional view taken along line H-■ in Figure 1, Figure 3 is a side view of the outer collar of the first bearing, and Figure 4 is a cross-sectional view taken along line ■-■ in Figure 3.
The sectional view, FIG. 5, is a sectional view taken along the line V-V in FIG. 3. 7...Tool 8...Tool holder 11...
・Tapered shaft 13...Main shaft 13a...End face
14...Tapered hole (1 other person)

Claims (1)

[Scope of Claims] In a spindle for a machine tool in which a spindle having a tapered hole at the tip of which a tool holder is mounted is rotatably supported by a bearing, when the tool holder is fixed to the spindle, the tapered hole of the spindle and the end face of the spindle are simultaneously connected. A spindle for a machine tool, characterized in that it is formed so as to be able to come in close contact with a tool holder.