JP2957252B2 - Spindle clamping device for machine tools - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a spindle clamping mechanism for a machine tool, and more particularly to a clamping device for a spindle having a double structure such as a boring shaft and a milling shaft of a horizontal boring milling machine. .

(Prior Art) A first main shaft rotatably supported on a main spindle head and a second main shaft inside the first main shaft rotatably supported and supported so as to be able to advance and retreat in the axial direction. 2. Description of the Related Art In a spindle clamping mechanism of a machine tool, various spindle clamping devices are used.

For example, in a horizontal boring milling machine, when the first spindle is a milling axis and the second spindle is a boring axis,
There are roughly the following two methods.

(1) A thin shell ring between a milling shaft rotatably supported on the spindle head and a boring shaft inside the milling shaft rotatably supported and axially movable back and forth. (Similar to the clamp ring shown in the specification of Japanese Utility Model Publication No. 62-43684), in which pressurized oil is constantly supplied to clamp the second spindle to the first spindle.

(2) As shown in Japanese Utility Model Publication No. Sho 62-43684, a clamp system that has a self-pressurized oil holding function built into the second spindle and clamps the first spindle and the second spindle, specifically, freely rotatable around the spindle head A thin wall provided on a first main shaft and a second main shaft between a milling shaft rotatably supported by the boring shaft and a boring shaft rotatably supported inside the same milling shaft and rotatably supported in an axial direction. A first main shaft and a second main shaft constituted by a shell ring, an accumulator for supplying pressure oil to the oil ring, an oil supply unit provided on the accumulator, and an oil supply unit provided at a fixed position separated from the milling shaft are clamped. It is a method.

(Problems to be Solved by the Invention) However, in the above-described spindle clamping mechanism for a machine tool, in the case of the above-described method (1), the pressurized oil is always supplied or the pressurized oil is held during the rotation of the spindle. Must. Therefore, in the oil chamber during cutting, the first spindle rotates at high speed, and the amount of heat generated during rotation increases, and the axial expansion of the second spindle due to this thermal expansion has a large effect on machining accuracy. Become.

Further, in the case of the method (2), leakage of pressure oil during rotation of the main shaft is inevitable, so that long-time operation cannot be performed.

Therefore, conventionally, cutting had to be interrupted, the second spindle was positioned at a constant angle position, the phases of the lubrication unit and the lubrication unit were matched, and work for lubricating the thin shell ring had to be performed. .

Also, if there is a leak of pressurized oil, the oil supply pressure of the thin shell ring decreases, and it is difficult to reliably clamp the main shaft with high rigidity. Further, the working time for refueling the thin shell ring has reduced the operation rate.

The present invention has been made in view of the above problems, and an object thereof is to provide a first spindle which is rotatably supported on a spindle head and is rotatably supported inside the first spindle. Another object of the present invention is to provide a spindle clamping device for a machine tool capable of securely clamping a second spindle supported so as to be able to advance and retreat in the axial direction with high rigidity.

Another object of the present invention is to provide a spindle clamping device for a machine tool that suppresses displacement caused by thermal expansion of a first spindle and a second spindle.

(Means for Solving the Problems) In order to solve the above-mentioned problems, a spindle clamping device for a machine tool according to the present invention partially forms a space between a first spindle and a second spindle, and An elastic member is provided in a space for holding the second main shaft, and a pair of an inner ring and an outer ring combining a conical tapered surface configured to clamp the first main shaft and the second main shaft by the action of the elastic member. An oil chamber is formed on one side of a pair of clamp rings for releasing the clamp between the first main shaft and the second main shaft, and a contact portion of the spindle head supporting the first main shaft and the second main shaft is provided. A hydraulic device is provided for supplying pressure oil to the oil chamber through a static pressure pocket having an air hole connected to the compressed air supply device.

Further, a space is partially formed between the first main shaft and the second main shaft, an elastic member is provided in the space, and a conical tapered surface that clamps the first main shaft and the second main shaft by the action of the elastic member is assembled. A pair of clamp rings composed of the combined inner ring and outer ring are disposed symmetrically with respect to the elastic member, and an oil chamber is provided on one side of the pair of clamp rings to release the clamp of the first main shaft and the second main shaft. A hydraulic device that supplies pressurized oil to the oil chamber via a static pressure pocket is provided at a contact portion between the first spindle and the spindle head supporting the first spindle.

Further, the pair of clamp rings may be disposed symmetrically with respect to the elastic member. It is preferable to use a spring and a compression coil spring as the elastic member.

Further, an air hole for supplying compressed air may be formed in the static pressure pocket, and a compressed air supply device for intermittently supplying compressed air may be provided.

(Operation) The spindle clamping mechanism of the machine tool of the present invention operates as follows.

The first main shaft is rotatably supported by the spindle head, and the second main shaft is provided inside the first main shaft so as to be rotatably supported, and is provided with a main shaft head having a main shaft head supported so as to be able to advance and retreat in the axial direction. In the clamping mechanism, when the first main shaft and the second main shaft are clamped, the pair of clamp rings press each other by the action of the elastic member, and act so as to clamp the first main shaft and the second main shaft. .

When releasing the clamp between the first main shaft and the second main shaft, pressure oil from a hydraulic device acts on the oil chamber on one side of the pair of clamp rings against the elastic member to release the clamp.

Further, when a pair of clamp rings are disposed symmetrically with respect to the elastic member, pressure oil from a hydraulic device acts on the oil chamber from both directions on the pair of clamp rings, and the first main shaft and the second Release the clamp on the twin spindle.

In addition, pressure oil is supplied to a contact portion between the first spindle and the spindle head supporting the first spindle via a static pressure pocket, and is used to release the pressing force of the clamp ring.

Since the compressed air from the compressed air supply device is intermittently supplied to the oil chamber of the first main shaft through an air hole, heat generation of the first main shaft is eliminated by eliminating static pressure oil in the oil chamber on the milling shaft side. And the displacement due to thermal expansion of the first main spindle and the front second main spindle can be suppressed.

In particular, since a groove for oil drain is formed on the circumference of the contact surface of the clamp ring that comes into contact with the second main spindle, the oil film on the second main spindle can be eliminated, and a reliable clamp without slipping can be achieved. I can do it.

(Example) Hereinafter, an example of a spindle clamping device for a machine tool according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of a spindle clamping device for a machine tool according to the present invention.

The present embodiment relates to a spindle clamping device of a horizontal boring milling machine in which a first spindle is a milling axis and a second spindle is a boring axis. As shown in FIG. Is rotatably supported via a boring shaft 4
Is rotatably supported inside the milling shaft 1,
Further, it is supported so as to be able to advance and retreat in the axial direction by a drive mechanism not shown.

In the spindle clamping device 10, a ring-shaped space 11 is formed between the milling shaft 1 and the boring shaft 4 on the side of the milling shaft 1, and a space 11 for holding the milling shaft 1 and the boring shaft 4.
A spring 12 is provided as an elastic member, and clamp rings 13 are fitted on both sides of the spring 12, respectively.
These clamp rings 13 and 14 are composed of outer rings 13A and 14A and inner rings 13B and 14B, respectively, with different directions of tapered surfaces.
The inner rings 13B, 14B can move in the axial direction, and the outer rings 13A, 1
It is configured to restrict only 4A. The milling shaft 1 and the boring shaft 4 are configured to be clamped by the action of the clamp rings 13 and 14. Since the shape of the pair of upper and lower clamp rings 13 and 14 is the same,
Is shown in more detail in the sectional view of FIG. In FIG. 2, the clamp rings 13 and 14 include an outer ring 13A and an inner ring 13A.
B, and conical tapered surfaces are movably opposed to each other. On the inner surface of the inner ring 13B, a groove 16 for oil drain is spirally engraved on the circumference, and in the axial direction, notch grooves 17 are cut at equal intervals on the circumference toward one end. . The outer ring 13A is constrained by the milling shaft 1 in the space 11, so that only the inner rings 13B and 14B can move in the axial direction. Reference numeral 18 denotes a seal member located on the space 11 side and in contact with the milling shaft 1 and the boring shaft 4 via an O-ring 18a. One side surface of the seal members 18A, 18B is the inner ring 13B, 1
4B, and the other side is in contact with oil chambers 19, 19, respectively. The oil chambers 19, 19 are connected to an oil passage 20 drilled in the milling shaft 1. The oil supply side of the oil passage 20 comes into contact with a hydraulic bush 21 fixed to the spindle head 2 side. A groove is formed in the inner peripheral surface of the hydraulic bush 21 to form a static pressure pocket 22.
A supply port of a hydraulic supply device (not shown) is connected to the static pressure pocket 22 via a joint 23.

In FIG. 1, reference numeral 15 denotes a collar for adjusting the spring force of the spring 12 when the ring 14 is assembled.

Furthermore, an air hole 22a for supplying compressed air is formed in the static pressure pocket 22, and the air hole 22a is connected to a compressed air supply device for intermittently supplying compressed air. It should be noted that the compressed air supply device is not shown in the figure because of a known technique.

The spindle clamping mechanism of the machine tool according to the present embodiment operates as follows.

As shown in FIG. 1, the milling shaft 1 is rotatable on a spindle head 2 via a bearing 3, and the boring shaft 4 is inside the milling shaft 1 and is rotatable with the milling shaft 1 and is not shown. It can be moved back and forth in the axial direction by the drive mechanism.

When clamping one milling shaft and boring shaft 4,
As shown in FIG. 3, the pressure oil from the hydraulic device is turned off, and the force of the spring 12 acts on the inner rings 13B, 14B, and the outer rings 13A, 1B.
The inner rings 13B and 14B bite into 4A, and clamp between the milling shaft 1 and the boring shaft 4 is performed. In this clamp, the cutout grooves 17 of the inner rings 13B and 14B are contracted with respect to the outer rings 13A and 14A, so that the tapered surfaces can be fitted and bitten.

In addition, since the grooves 16 for oil drainage on the inner surfaces of the inner rings 13B and 14B are provided, the oil on the outer peripheral surface of the boring shaft 4 is oiled when the inner rings 13B and 14B move, so that metal contact is made. Both can be clamped without slipping. Therefore, the clamp ring between the milling shaft 1 and the boring shaft 4
Since it can be integrated through the 13, it can withstand high rigidity sufficiently.

When the milling shaft 1 and the boring shaft 4 are unclamped, the pressure oil from the hydraulic device is connected to the joint as shown in FIG.
23. Supply hydraulic pressure to the oil chamber 19 through the static pressure pocket 22 of the hydraulic bush 21 and apply an external force against the force of the spring 12 to the inner rings 13B and 14B from the sealing member contacting via the O-ring 18a. . As shown in FIG. 4, the inner rings 13B and 14B are moved inward by the force of the oil pressure in the oil chamber 19 against the force of the springs 12. Then, the inner rings 13B and 14B are separated from the outer rings 13A and 14A, and the milling shaft 1 and the boring shaft 4 have no tightening force, and the clamp is released.

When the milling shaft 1 rotates during clamping,
When oil exists in the static pressure pocket 22, heat is generated between the static pressure pocket 22 and the hydraulic bush 21 by shearing of the oil. For this reason, during operation, compressed air is intermittently supplied to the static pressure pocket 22 through the air hole 22a, and the static pressure oil in the static pressure pocket 22 on the milling shaft 1 side is eliminated, so that the milling shaft 1 Heat generation can be reduced, and as a result, thermal expansion of the entire spindle system can be reduced.

FIG. 5 is a sectional view showing a second embodiment of the spindle clamping device according to the present invention.

As shown in FIG. 5, in the spindle clamping device 30, a cylindrical space 11 is formed on the milling shaft 1 side between the milling shaft 1 and the boring shaft 4, and the milling shaft 1 and the boring shaft 4 are held therebetween. For this reason, a counter spring 12 is provided in the space 11, and a clamp ring 13 is provided only on one side of the counter spring 12. The operation of the clamp ring 13 clamps the milling shaft 1 and the boring shaft 4. With this configuration, the number of components can be reduced as compared with the previous embodiment.

However, since the direction of the taper of the clamp ring 13 is inclined downward to the right, it can sufficiently withstand the cutting force from the left side of the drawing as in drilling. Note that other operations and effects of this embodiment are the same as those of the above-described embodiment, and thus description thereof will be omitted.

FIG. 6 is a sectional view showing a third embodiment of the present invention.
Since this embodiment is a modification of the first embodiment, the same components as those of the first embodiment will be described using the same reference numerals.

In this embodiment, when the boring shaft is moved, the boring shaft may not be accurately positioned due to the resistance of the O-ring of the sealing member.
This is an example in which a milling shaft and a boring shaft can be clamped via a clamp ring.

Reference numeral 30 denotes a spindle clamping mechanism. The spindle clamping mechanism 30 forms a ring-shaped space 11 between the milling shaft 1 and the boring shaft 4 on the side of the milling shaft 1, and a ring fitted to the boring shaft 4. The Sara spring 12 is fitted in the spacer 31 having a shape.

Further, a pair of inner and outer clamp rings 13 and 14 are respectively fitted on both sides of the flat spring 12, and seal members 18A and 18B are respectively fitted on both ends thereof. The seal member 18A is provided with a ring-shaped spacer 32 fitted to the boring shaft 4.
, Via an O-ring 18a. One side surface of the seal member 18A is in contact with the outer ring 14A, and the other side is in contact with the oil chamber 19, respectively. The sealing member 18B has an O-ring 18a on an extension 33a extending to a ring-shaped lid 33 fitted to the boring shaft 4.
Are in contact with each other. The ring-shaped lid 33 is fixed to the front end of the milling shaft 1 by bolts 34. One side of the seal member 18B is in contact with the outer ring 13A similarly to the seal member 18A, and the other side is in contact with the oil chamber 19, respectively.

The shape of the pair of inner and outer clamp rings 13 and 14 is the first
It has the same shape as the clamp rings 13A, 13B shown in the embodiment (see FIG. 2), except that the direction of the tapered surface is different, and the inner rings 13B, 14B are restrained by the milling shaft 1 in the space 11, and Only the rings 13A and 14A are configured to be movable in the axial direction. The oil chambers 19, 19 are respectively connected to oil passages 20 drilled in the milling shaft 1. The oil supply side of the oil passage 20 can be brought into contact with a hydraulic bush 21 fixed to the spindle head 2 side. A ring-shaped groove is carved on the inner peripheral surface of the hydraulic bush 21 to form a static pressure pocket 22. Static pressure pocket 22
Is connected via a joint 23 to a hydraulic supply device not shown. Therefore, when the pressure oil from the hydraulic pressure supply device is supplied to the static pressure pocket 22, the seal members 18A and 18B compress the flat spring 12 via the outer rings 13 and 14, and release the clamp of the clamp rings 13 and 14. . The spindle clamping mechanism of the machine tool according to the present embodiment operates as follows.

When clamping milling shaft 1 and boring shaft 4,
The supply of hydraulic pressure to the hydraulic system is cut off, and the hydraulic pressure in the oil chambers 19 and 19 is released. As a result, only the outer rings 13A and 14A can be moved in the axial direction, so that the outer rings 13A and
4A bites in and clamps between milling shaft 1 and boring shaft 4. With this clamp, the cutout grooves 17 of the inner rings 13B, 14B contract with the outer rings 13A, 14A, so that the tapered surfaces bite each other. When the inner rings 13B, 14B contract, the outer peripheral surface of the boring shaft 4 is oiled when the inner rings 13B, 14B are contracted by the oil draining grooves 16 on the inner surfaces of the inner rings 13B, 14B. The shaft 4 does not slip.

When the milling shaft 1 and the boring shaft 4 are unclamped, the hydraulic oil from the hydraulic device is connected to the joint 2 as shown in FIG.
3, the oil chambers 19, 1 through the static pressure pockets 22 of the hydraulic bush 21
Supply 9 As a result, an external force is applied to the outer rings 13A and 14A by the seal members 18 and 18 against the force of the spring 12, so that the outer rings 13A and 14A are unclamped.

That is, the outer ring 13 is
A and 14A move inward respectively against the force of the counter spring 12, and the clamping rings 13 and 14 lose their clamping force, releasing the clamping of the milling shaft 1 and the boring shaft 4.

 FIG. 7 is a sectional view showing a fourth embodiment of the present invention.

This embodiment is a modification of the second embodiment. When the boring shaft is moved, the boring shaft cannot be accurately positioned due to the resistance of the O-ring of the sealing member. This is an example in which the resistance is eliminated and the milling shaft and the boring shaft can be clamped by the clamp ring.

The same parts as those in the second embodiment will be described using the same reference numerals.

In the figure, a spindle clamping mechanism 40 forms a cylindrical space 11 on the milling shaft 1 side between the milling shaft 1 and the boring shaft 4, and a ring-shaped spacer 31 fitted to the milling shaft 1 and the boring shaft 4. Sarah spring 12 is inserted into.

A clamp ring 13 is provided only on one side of the flat spring 12, and the operation of the clamp ring 13 clamps one milling shaft and the boring shaft 4. Sign
Reference numeral 18 denotes a seal member which is in contact with a ring-shaped spacer 32 fitted on the milling shaft 1 and the boring shaft 4 via the O-ring 18a. One side of the seal member 18 is an outer ring
The other side is in contact with the oil chamber 19, respectively. 4th
The operation of this embodiment is the same as that of the third embodiment.

8 and 9 are diagrams showing the cutting performance when the spindle clamping device according to the present invention is used, FIG. 8 is a diagram showing the milling capability, and FIG. 9 is a diagram showing the cutting capability of the end mill. . In the figure, the vertical axis is the cutting amount (cc), and the horizontal axis is L / D
(Where L is the length of the boring shaft with reference to the milling shaft end, and D is the diameter of the boring shaft). In the case of milling, when the L / D is 3-4, the one that adopts the spindle clamping device according to the present invention shows about twice the cutting ability of the one that adopts the conventional clamping device, and the cutting ability of the end mill is The performance was about four times that of the above, and good results were obtained in each case.

(Effect of the Invention) As described above, the spindle clamping device for a machine tool according to the present invention includes a pair of clamp rings for clamping the first spindle and the second spindle by the action of a spring, and pressure oil in the oil chamber on the clamp ring side. Since it is equipped with a hydraulic device that supplies the first spindle, it is rotatably supported inside the first spindle and the first spindle,
In addition, the second main shaft supported to be able to advance and retreat in the axial direction can be reliably clamped and unclamped with high rigidity. Compared to the conventional hydraulic clamping system, the clamping device of the present invention is a mechanical clamping system, so troubles due to pressure oil, ie, decrease in clamping force due to heat generation hydraulic leak, increase in running cost due to operation of the hydraulic device And other problems can be solved. In addition, if a groove for oil drain is formed on the contact surface of the clamp ring that contacts the second main shaft, the first main shaft and the second main shaft can be reliably clamped with high rigidity without slipping. it can.

Furthermore, through the air hole in the static pressure pocket of the first spindle,
By intermittently supplying the compressed air, the displacement due to the thermal expansion of the first main shaft and the second main shaft can be further suppressed.

[Brief description of the drawings]

1 is a sectional view showing a first embodiment of a spindle clamping device for a machine tool according to the present invention, FIG. 2 is a sectional view showing a section of a pair of inner and outer clamp rings, and FIG. 3 is a first spindle and a second spindle. FIG. 4 is a partial sectional view showing a clamped state of the main spindle, FIG. 4 is a partial sectional view showing an unclamped state of the first spindle and the second spindle, and FIG.
FIG. 6 is a sectional view showing a second embodiment of a spindle clamping device for a machine tool, FIG. 6 is a sectional view showing a third embodiment of the same, and FIG. 7 is a sectional view showing a fourth embodiment of the present invention. FIG. 8 is a diagram comparing the milling ability of the apparatus of the embodiment of the present invention with that of the conventional example, and FIG. 9 is a view showing the cutting ability of the end mill by the apparatus of the present invention. [Explanation of reference numerals] 1 ... milling shaft, 2 ... spindle head, 4 ... boring shaft, 12
…… Sarabane, 13,14 …… Clamp ring, 13A, 14A ……
Outer ring, 13B, 14B ... Inner ring, 16 ... Oil drain groove, 17 ... Notch groove, 19 ... Oil chamber, 22 ... Static pressure pocket,
22a: Air vent.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23B 19/02 B23B 39/02

Claims (4)

(57) [Claims] A first main shaft rotatably supported by the main spindle head; and a second main shaft inside the first main shaft rotatably supported and supported so as to be able to advance and retreat in the axial direction. In the spindle clamping mechanism of a machine tool, a space is partially formed between the first spindle and the second spindle, an elastic member is provided in the space, and the first spindle and the second spindle are formed by the action of the elastic member. A pair of clamp rings consisting of an inner ring and an outer ring in which conical tapered surfaces for clamping the main shaft are combined are provided, and one of the pair of clamp rings is used to release the clamp of the first main shaft and the second main shaft. An oil chamber is formed on the side, and a contact portion between the first spindle and the spindle head supporting the first spindle is formed in the oil chamber through a static pressure pocket having an air hole connected to a compressed air supply device. Hydraulic device for supplying pressurized oil is provided A spindle clamping device for a machine tool, comprising: A first main shaft rotatably supported by the main shaft head; and a second main shaft inside the first main shaft rotatably supported and rotatably supported in the axial direction. In the spindle clamping mechanism of a machine tool, a space is partially formed between the first spindle and the second spindle, an elastic member is provided in the space, and the first spindle and the second spindle are formed by the action of the elastic member. A pair of clamp rings composed of an inner ring and an outer ring in which conical tapered surfaces for clamping the main shaft are combined are disposed symmetrically with respect to the elastic member, and the first main shaft and the second main shaft are clamped. An oil chamber is formed on one side of the pair of clamp rings in order to release the pressure oil, and a pressure oil is applied to the oil chamber via a static pressure pocket at a contact portion between the first spindle and the spindle head supporting the first spindle. Characterized by having a hydraulic device for supplying Spindle clamping device for machine tools. 3. The spindle clamping device for a machine tool according to claim 2, wherein the elastic member is a flat spring. 4. The spindle clamping device for a machine tool according to claim 2, wherein the elastic member is a compression coil spring.