JPH04176504A - Main spindle clamp device for machine tool - Google Patents

Abstract

PURPOSE:To surely clamp a second main shaft with high rigidity by providing an elastic member in a space for holding a first main shaft and the second main shaft and by providing a pair of clamp rings constituted to clamp the first and the second main shafts by an action of the elastic member. CONSTITUTION:When a milling shaft 1 and a boring shaft 4 are to be clamped, pressure oil from a hydraulic device is cut off, a force of a disc spring 12 acts on inner rings 13B and 14B, and the inner rings 13B and 14B bite into outer rings 13A and 14A so as to carrying out clamping between the milling shaft 1 and the boring shaft 4. This clamp is made to bite by contracting a notch groove 17 of the inner rings 13B and 14B against the outer rings 13A and 14B so as to engage tapered surfaces with each other. Also, as a groove 16 for throwing oil is provided on inner surfaces of the inner rings 13B and 14B, oil on the outer circumferential surface of the boring shaft 4 is thrown as the inner rings 13B and 14B are moved, which enables metal-to-metal contact and clamping without slippery between them.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a main spindle clamping mechanism for a machine tool, and particularly to a clamping device for a dual structure main spindle such as a boring spindle and a milling spindle of a cross-boring milling machine. .

(Prior art) A first main shaft rotatably supported by a main spindle head, and a second main shaft located inside the first main shaft, rotatably supported and movable in the axial direction. Various types of spindle clamping devices are used in spindle clamping mechanisms for machine tools.

For example, in a cross-boring milling machine, when the first spindle is a milling spindle and the second spindle or boring spindle is used, there are two main methods:

(1) Thin shell ring between a milling shaft rotatably supported on the spindle head and a boring shaft located inside the milling shaft, rotatably supported and movable in the axial direction A method in which pressure oil is constantly supplied to (a member similar to the clamp ring shown in Japanese Utility Model Publication No. 62-43684) and the second main shaft is clamped to the first main shaft.

(2) As shown in Utility Model Publication No. 62-43684, this is a clamping method in which the second spindle has a self-pressure oil retention function and clamps the first and second spindles. Specifically, the spindle head is rotatable. Thin walls provided on the first and second main shafts between the milling shaft, which is rotatably supported on the milling shaft, and the boring shaft, which is rotatably supported on the inside of the milling shaft and can move forward and backward in the axial direction. A shell ring, an accumulator that supplies pressure oil to the oil ring, a lubrication unit installed in the accumulator,
This is a method in which a first main shaft and a second main shaft are clamped by an oil supply unit provided at a fixed position separate from the milling shaft.

(Problem to be Solved by the Invention) However, in the spindle clamping mechanism of the machine tool described above, in the case of the method (1) above, pressure oil is always supplied or pressure oil is maintained while the spindle is rotating. Must. Therefore, during cutting, the first spindle rotates at high speed in the static pressure pocket area, which generates a large amount of heat during rotation, and the elongation of the second spindle in the axial direction due to this thermal expansion has a large impact on machining accuracy. It turns out.

Furthermore, in the case of the method (2), leakage of pressure oil during rotation of the main shaft is unavoidable, making it impossible to operate for a long time.

Therefore, conventionally, it was necessary to interrupt cutting, position the second spindle at a constant angle, align the phases of the lubrication unit and the lubrication unit, and perform work to lubricate the thin shell ring. .

Furthermore, if pressure oil leaks, the oil supply pressure of the thin shell ring decreases, making it difficult to securely clamp the main shaft with high rigidity. In addition, the working time required to supply oil to the thin-walled shell ring resulted in a decrease in the operating rate.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a first spindle that is rotatably supported on the spindle head, and a first spindle that is rotatably supported on the inside of the first spindle. Another object of the present invention is to provide a main shaft clamping device for a machine tool that can reliably clamp a second main shaft supported so as to be movable 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 of the first spindle and the second spindle due to thermal expansion.

(Means for Solving the Problems) In order to solve the above problems, the main spindle clamping device for a machine tool of the present invention partially forms a space between the first spindle and the second spindle, and An elastic member is provided in the space to hold the two main shafts, and a pair of clamp rings are provided that clamp the first and second main shafts by the action of the elastic member, and the clamps of the first and second main shafts are released. In order to do this, an oil chamber is formed on one side of the pair of wedges, and a hydraulic device is installed at the contact area between the first spindle and the spindle head that supports the first spindle to supply pressurized oil to the oil chamber via a static pressure pocket. It is.

The pair of clamp rings consists of an inner ring and an outer ring, which are made by combining conical tapered surfaces.The inner ring has grooves for draining oil on the circumference, and grooves for shrinkage are evenly spaced on the inner ring. A slit groove may also be formed.

Furthermore, the pair of clamp rings may be arranged symmetrically with respect to the elastic member. It is preferable to use a flat spring or a compression coil spring as the elastic member.

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

(Function) The spindle clamping mechanism of the machine tool of the present invention functions as follows.

The first spindle is rotatably supported by a spindle head, and the second spindle is rotatably supported inside the first spindle, and the spindle head is supported so that it can move forward and backward in the axial direction. In the spindle clamping mechanism, when the first spindle and the second spindle are clamped, the pair of clamp rings press against each other due to the action of the elastic member and act to clamp the first spindle and the second spindle. do.

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

Furthermore, when a pair of clamp rings is arranged symmetrically with respect to the elastic member, pressure oil from the hydraulic system acts on the oil chamber from both directions on the pair of clamp rings, causing the first main shaft and the first main shaft to Release the clamp on the two main shafts.

Note that pressure oil is supplied to the contact portion between the first main shaft and the spindle head that supports the first main shaft through 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 static pressure pocket of the first spindle through the air hole, by eliminating the static pressure oil in the static pressure pocket on the milling shaft side, It is possible to prevent the main shaft from generating heat and suppress displacement of the first main shaft and the front second main shaft due to thermal expansion.

In particular, a groove for removing oil is formed on the circumference of the contact surface of the clamp ring that comes into contact with the second spindle, making it possible to eliminate the oil film on the second spindle, ensuring reliable lamp operation without slipping. I can do it.

(Example) Hereinafter, an example of the spindle clamp device for a machine tool of 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.

This embodiment relates to a spindle clamping device for a cross-boring milling machine in which the first spindle is a milling spindle and the second spindle is a boring spindle.As shown in FIG. The boring shaft 4 is rotatably supported via the
It is rotatably supported inside the milling shaft 1, and is supported so as to be movable in the axial direction by a drive mechanism (not shown).

In the spindle clamping device 10, a ring-shaped space 11 is formed on the milling shaft 1 side between the milling shaft 1 and the boring shaft 4, and an elastic member is used in the space 11 to clamp the milling shaft 1 and the boring shaft 4. A counter spring 12 is provided, and clamp rings 13 are fitted onto both sides of the counter spring 12, respectively. The clamp rings 13 and 14 each consist of outer rings 13A, 14A and inner rings 13B, 14B, with tapered surfaces facing different directions, and an inner ring 13B.

14B is movable in the axial direction, and outer ring 13A.

It is configured such that only 14A is restrained. The milling shaft 1 and the boring shaft 4 are configured to be clamped by the action of clamp rings 13 and 14. Since the shapes of this pair of upper and lower clamp rings 13 and 14 are the same, the clamp ring 13 is shown in more detail in the sectional view of FIG. 2, taking the clamp ring 13 as an example. In FIG. 2, the clamp ring 13.14 consists of a combination of an outer ring 13A1 and an inner ring 13B1, the conical tapered surfaces of which are movably opposed to each other. On the inner surface of the inner ring 13B, oil draining grooves 16 are spirally carved on the circumference, and in the axial direction, notch grooves 17 are cut out at equal intervals on the circumference toward one side end. .

The outer ring 13A is restrained by the milling shaft 1 within the space 11, and only the inner rings 13B and 14B are configured to be movable in the axial direction. Reference numeral 18 is 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 of the seal members 18A and 18B is in contact with the inner rings 13B and 14B, respectively, and the other side are in contact with the static pressure pockets 19, 19, respectively. Static pressure pocket 19.19 is an oil passage 20 drilled in the milling shaft 1.
is connected. 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 carved on the inner circumferential surface of the hydraulic bushing 21 to form a static pressure pocket 22. The static pressure pocket 22 has a joint 2
3, a supply port of a hydraulic pressure supply device (not shown) is connected.

In FIG. 1, reference numeral 15 is 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 that supplies compressed air intermittently. In addition,
The compressed air supply device is not shown because it is a known technique.

The spindle clamping mechanism of the machine tool of this embodiment operates as follows.

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

When clamping the milling shaft 1 and the boring shaft 4, as shown in FIG. 3, the pressure oil from the hydraulic system is turned off and the force of the spring 12 is applied to the inner ring 13B.

14B, the inner rings 13B and 14B bite into the outer rings 13A and 14A, and the milling shaft 1 and the boring shaft 4
Perform a clamp between the This clamp has outer ring 1
The notch grooves 17 of the inner rings 13B and 14B contract relative to the inner rings 3A and 14A, allowing the tapered surfaces to fit and bite into each other.

Also, grooves 1 for draining oil on the inner surfaces of the inner rings 13B and 14B.
6, so the inner ring 13B.

When 14B moves, the oil on the outer peripheral surface of the boring shaft 4 is drained, so that metal contact can be made and both can be clamped without slipping. Therefore, since the milling shaft 1 and the boring shaft 4 can be integrated via the clamp ring 13, they can sufficiently withstand high rigidity.

When unclamping milling shaft 1 and boring shaft 4,
Pressure oil from the hydraulic system is supplied to the joint 23 as shown in FIG.
, Hydraulic pressure is supplied to the static pressure pocket 19 through the static pressure pocket 22 of the hydraulic bush 21, and an external force that resists the force of the flat spring 12 is applied to the inner rings 13B and 14B from the seal member in contact with the O ring 18a. . As shown in FIG. 4, the inner ring 1 is
3B and 14B each move inward against the force of the bell spring 12. Then, the inner rings 13B and 14B are separated from the outer ring 13A and 114A, the force to tighten the milling shaft 1 and the boring shaft 4 is lost, and the clamp is released.

Note that when the milling shaft 1 rotates during clamping, if oil is present in the static pressure pocket 22, the hydraulic bushing 21
Heat generation occurs due to shearing of the oil between the two. 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 pocket 22 on the side of the milling shaft 1 is
By eliminating the hydrostatic oil in the milling shaft 2, the heat generation of the milling shaft 1 can be kept low, and as a result, the thermal expansion of the entire spindle system can be kept low.

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 clamped. A counter spring 12 is provided in the storage space 11, and the counter spring 1
A clamp ring 13 is provided only on one side of 2.

The action of the clamp ring 13 clamps the milling shaft 1 and the boring shaft 4. With this configuration, the number of parts can be reduced compared to the previous embodiment.

However, since the taper direction of the clamp ring 13 is sloped downward to the right, it can sufficiently withstand cutting force from the left side of the drawing as in drilling. Note that the other functions and effects of this embodiment are the same as those of the above-described embodiment, and therefore their explanation 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 in the first embodiment will be described using the same reference numerals.

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

Reference numeral 30 denotes a spindle clamping mechanism, and this spindle clamping mechanism 30 forms a ring-shaped space 11 on the milling spindle 1 side between the milling spindle 1 and the boring spindle 4, and a ring-shaped space 11 is formed between the milling spindle 1 and the boring spindle 4. A flat spring] 2 is inserted into the shaped spacer 31.

Further, a pair of inner and outer clamp rings 13 and 14 are fitted on both sides of the spring 12, and seal members 18A and 18B are fitted on both ends thereof, respectively. This seal member 18A is in contact with a ring-shaped spacer 32 fitted to the boring shaft 4 via an O-ring 18a. One side of the seal member 18A is in contact with the outer ring 14A,
The other sides are in contact with static pressure pockets 19, respectively. The sealing member 18B is a ring-shaped lid 33 fitted onto the boring shaft 4.
The O-ring 18a is in contact with the extending portion 33a extending through the O-ring 18a. The ring-shaped lid 33 is fixed to the front end of the milling shaft 1 with bolts 34. Seal member 1
One side of 8B has outer ring 13 similar to seal member 18A.
A, and the other side is in contact with the static pressure pocket 19, respectively.

The shape of this pair of inner and outer clamp rings 13 and 14 is the same as the clamp ring 13A shown in the first embodiment.

Although it has the same shape as 13B (see Fig. 2), the direction of the tapered surface is different, and the inner rings 13B and 14B are restrained by the milling shaft 1 within the space 11, and only the outer rings 13A and 14A move in the axial direction. It is configured so that it can be done. The hydrostatic pockets 19,19 are each connected to an oil channel 2o drilled in the milling shaft 1. The oil supply side of the oil passage 20 is capable of coming into contact with a hydraulic bush 21 fixed to the spindle head 2 side. A ring-shaped groove is carved into the inner circumferential surface of the pressure 7' bush 21 to form a static pressure pocket 22.

The static pressure pocket 22 is connected to a hydraulic pressure supply device (not shown) via a joint 23. Therefore, when pressure oil from the hydraulic supply device is supplied to the static pressure pocket 22, the seal members 18A, 18B compress the bell spring 12 via the outer ring 13.14, and release the clamp of the clamp ring 13.14. .

The spindle clamping mechanism of the machine tool of this embodiment operates as follows.

When clamping the milling shaft 1 and the boring shaft 4, the supply of hydraulic pressure from the hydraulic system is cut off and the hydraulic force in the hydrostatic pocket 19, 19 is released. As a result, the outer rings 13A, 1
Since it is configured so that only 4A can move in the axial direction,
Due to the force of the spring 12, the fixed side inner rings 13B, 1
Outer rings 13A and 14A bite into 4B to clamp between milling shaft 1 and boring shaft 4. With this clamp, the inner ring 1 is
The notch grooves 17 of 3B and 14B contract and the tapered surfaces dig into each other. When the inner ring 13B, 114B moves, the outer peripheral surface of the boring shaft 4 is oil-drained by the oil-draining groove 16 on the inner surface of the inner ring 13B, 14]3, so that metal contact is possible, and the milling shaft 1 and the boring The shaft 4 never slips.

When unclamping the milling shaft 1 and the boring shaft 4, pressurized oil from the hydraulic system is applied to the joint 23 as shown in FIG.
, via the hydrostatic pocket 22 of the hydraulic bushing 21 to the hydrostatic pocket 19.19. As a result, the seal springs 1 are attached to the outer rings 13A and 14A by the seal members 18.18.
An external force that resists the force 2 acts, resulting in unclamping.

In other words, the outer rings 1:3A and 14A move inwardly against the force of the spring 12 due to the hydraulic force of the static pressure pockets 19, 19, and the clamp rings 13, 14 lose their tightening force, and the milling shaft 1 and release the clamp on 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 moving the boring shaft, 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 the resistance of the ring is eliminated and the milling shaft and boring shaft can be clamped with a clamp ring.

Components that are the same as those in the second embodiment will be described using the same reference numerals.

In the figure, the main 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 on the milling shaft 1 and the boring shaft 4. A counter spring 12 is inserted into the.

A clamp ring 13 is provided only on one side of the spring 12, and the clamp ring 13 is configured to clamp the milling shaft 1 and the boring shaft 4.

Reference numeral 18 denotes an O-ring 18a attached to a ring-shaped spacer 32 located on the side of the space 11 and fitted onto the milling shaft 1 and the boring shaft 4.
This is a sealing member that comes into contact with the One side of the seal member 18 is in contact with the outer ring 13A, and the other side is in contact with the static pressure pocket 19.
are in contact with each other. The effect of the fourth embodiment is the same as that of the third embodiment.
This is similar to the embodiment.

Fig. 8 and Fig. 9 are diagrams showing the cutting capacity when using the spindle clamping device according to the present invention, Fig. 8 is a diagram showing the milling cutting capacity, and Fig. 9 is a diagram showing the cutting capacity of the end mill. . In the figure, the vertical axis is cutting amount (cc), and the horizontal axis is L/D.
(However, L indicates the length of the boring shaft based on the end of the milling shaft, and D indicates the diameter of the boring shaft.) In the case of milling, when L/D is 3 to 4, the machine using the spindle clamping device according to the present invention has a cutting capacity that is approximately twice that of the conventional clamping device, and in the case of the cutting capacity of an end mill, The performance was about 4 times higher, and good results were obtained in both cases.

(Effects 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 that clamp the first spindle and the second spindle by the action of a counter spring, and a pressurized oil chamber in the oil chamber on the clamp ring side. Equipped with a hydraulic system that supplies the pressure, the first spindle and the second spindle, which is rotatably supported inside the first spindle and can move back and forth in the axial direction, are reliably clamped with high rigidity. , can be unclamped. Compared to conventional hydraulic clamping systems, the clamping device of the present invention uses a mechanical or ramp system, so it is less prone to troubles caused by pressure oil, such as reduced clamping force due to heat-generating hydraulic leaks and increased running costs associated with the operation of the hydraulic system. Problems such as this can be solved. In addition, if a groove for draining oil is formed on the circumference of the contact surface of the clamp ring that contacts the second spindle, the first spindle and the second spindle can be reliably clamped with high rigidity without slipping. can.

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

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a first embodiment of a main spindle clamping device for a machine tool according to the present invention, FIG. 2 is a cross-sectional view showing a pair of inner and outer clamp rings, and FIG. Fig. 4 is a partial sectional view showing the clamped state of the main shaft; Fig. 4 is a partial sectional view showing the unclamped state of the first main shaft and the second main shaft;
The figure 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, 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 according to the embodiment of the present invention with that of a conventional example, and FIG. 9 is a diagram showing the cutting ability of an end mill using the apparatus of the present invention. 1... Milling shaft, 2... Spindle head, 4... Boring shaft, 12... Flat spring, 13.14... Clamp ring, 13A, 14A... Outer ring, 13B, 14B
...Inner ring, 16...Groove for draining oil, 17...
Notch groove, 19... Static pressure pocket, 22... Static pressure pocket, 22a: Air hole. Applicant's agent: Yu Sato / 3A 2. Country of origin 5. Figure deletion amount #B

Claims (1)

[Claims] 1. A first main shaft that is rotatably supported on the main spindle head, and a second main shaft that is rotatably supported inside the first main shaft and is supported so as to be movable in the axial direction. In the spindle clamping mechanism for 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 action of the elastic member allows the first spindle to A pair of clamp rings are provided for clamping the second main shaft, an oil chamber is formed on one side of the pair of clamp rings for releasing the clamp between the first main shaft and the second main shaft, and an oil chamber is provided on one side of the pair of clamp rings to release the clamp between the first main shaft and the second main shaft. A spindle clamping device for a machine tool, characterized in that a contact portion of a spindle head that supports a first spindle is provided with a hydraulic device that supplies pressurized oil to the oil chamber through a static pressure pocket. 2. A pair of clamp rings is composed of an inner ring and an outer ring, which are made by combining conical tapered surfaces, and the inner ring has grooves for draining oil on the circumference, and is evenly spaced for reduction. 2. The spindle clamping device for a machine tool according to claim 1, wherein the slit groove is cut out. 3. The spindle clamping device for a machine tool according to claim 1, wherein an air hole for supplying compressed air is formed in the static pressure pocket and a compressed air supply device is provided. 4. The spindle clamping device for a machine tool according to claim 1, wherein the pair of clamp rings are arranged symmetrically with respect to the elastic member. 5. The spindle clamping device for a machine tool according to claim 1, wherein the elastic member is a flat spring. 6. The spindle clamping device for a machine tool according to claim 1, wherein the elastic member is a compression coil spring.