JPH0249843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a clamping device used for clamping a tool to the tool spindle of a machine tool or a work pallet to the spindle of a rotary table. In particular, a pull stud protruding from the rear end of a tool or work pallet (hereinafter referred to as a tool, etc.) is pulled into the hollow part of the spindle by the collector using the pressing force of a disc spring and clamped to the tapered part of the spindle. This invention relates to a main shaft clamping device of the type.

[Conventional technology]

The structure of a conventional spindle clamping device is such that a drawbar is inserted concentrically into a hollow part of a spindle that is rotatably mounted in a housing, and the drawbar is opened and closed by moving axially to the tip region of the drawbar. A collet is attached, and the collet grips a pull stud at the rear end of a tool, etc. The drawbar is always biased backwards with respect to the main shaft by the pressing force of a large number of disc springs fitted in parallel on its outer circumferential surface, so tools etc. held by the collet are pushed into the hollow part of the main shaft. It is configured to be drawn into the main shaft hollow part and firmly held in close contact with the tapered part provided at the entrance area of the main shaft hollow part. When removing tools, etc., actuate the piston of the unclamping means provided at the rear of the housing to push the rear end of the drawbar forward overcoming the pressing force of the disc spring. The restriction is released and the opening is released, the grip of the pull stud is released and the tools etc. are freed.

[Problem that the invention seeks to solve]

In the prior art with the above-mentioned configuration, as shown in FIG. 3, the disc spring 22 that biases the drawbar 11 rearward is directly inserted into the outer periphery of the drawbar 11, so that it is difficult to grasp and release tools, etc. When the drawbar 11 moves linearly at this time, the inner circumferential surface of the disc spring 22 and the outer circumferential surface of the drawbar 11 come into sliding contact. Since the pressing force exerted by the disk spring 22 is strong, reaching, for example, 3 tons, the edge a causes scratches on the outer circumferential surface of the drawbar 11, which tends to gradually increase with each rotation. This increases the frictional resistance between the drawbar and the disc spring, resulting in a reduction in the clamping force against the tool and the like.

In addition, in order to ensure the stroke of the drawbar 11, a predetermined number of disc springs 22 are inserted into the drawbar 11 with the direction of inclination reversed, so that the outer peripheral areas of the disc springs 22 face each other. There are several locations where If the aforementioned scratches on the outer circumferential surface of the drawbar 11 become large and the disc springs 22 start to bite into them, the heights of the disc springs 22 in the radial direction also become uneven. Then, the amount of deflection of the disc spring changes from the initial setting, and the clamping force decreases. Moreover, at the facing portion, as shown in FIG. 4, the outer peripheral edge b of one of the disc springs 22 comes into contact with the side surface of the other disc spring 22 and rubs against each other, causing a phenomenon in which they damage each other. As this progresses further,
This will eventually lead to damage to the disc spring.

[Means for solving problems]

In order to solve the drawbacks of the prior art, the present invention reduces the rubbing action caused by the edges of the disc springs, which causes scratches between the drawbar and the disc spring, and between the disc springs, thereby reducing the gripping force. It is an object of the present invention to provide a main shaft clamping device that does not cause damage to disc springs or disc springs.

The purpose of this is to have a main shaft on which a tool or work pallet is mounted at the tip, and a hollow part that penetrates through the main shaft in the axial direction, which is inserted concentrically with the main shaft, and by reciprocating in the axial direction, the tool or work pallet can be attached to the back of the main shaft. A collet that can freely engage and disengage from a pull stud protruding from an end; a collet that is inserted into a hollow portion of the main shaft concentrically with the main shaft; a front end is attached to a rear part of the collet; and a rear end extends to the rear of the main shaft. The drawbar is provided between the existing drawbar and the inner periphery of a hollow part of the main shaft on the outer periphery of the drawbar, and is configured to generate a pressing force between the main shaft and the drawbar to urge the drawbar backward. A clamping device for a main shaft of a machine tool, comprising a plurality of disposed disc springs and an unclamping means for moving the drawbar forward against the pressing force of the disc springs until the collet is detached from the pull stud. And,
A plurality of the disc springs are stacked in the same direction to form a set of disc springs, and a plurality of sets of disc springs are arranged alternately in opposite directions, and the disc springs are arranged in a manner that allows the disc springs to expand and contract in the same direction. A sliding collar is fitted between the outer periphery of the drawbar and the inner periphery of the hollow part of the main shaft via a sliding collar that is slidable in the axial direction following the sliding collar. This is achieved by a clamping device of the spindle, characterized in that it comprises at least one flange locking the relative movement of the spindle.

Preferably, the sliding collar is fitted onto the outer peripheral surface of the drawbar, and the disc spring is fitted onto the outer peripheral surface of the sliding collar. By inserting the sliding collar between the drawbar and the disc spring, direct contact between the drawbar and the disc spring is eliminated.

A plurality of the sliding collars are arranged at predetermined intervals, at least one of which has an annular flange in the center and is provided at a ratio of one to two sets of disc springs, and the flange has an annular flange in the center. , the outer diameter of the central portion of the sliding collar is partially enlarged so as to isolate a set of disc springs whose inner peripheral regions are arranged close to each other and another set of disc springs. is desirable. As a result, almost no sliding movement occurs between the disc spring and the sliding collar.

It is preferable that the disc spring is formed as a flat surface so that an inner peripheral region that contacts the flange of the sliding collar and an outer peripheral region that faces and contacts another set of disc springs are in surface contact with each other. As a result, the contact between the disc springs facing each other, or the contact between the disc spring and the flange becomes surface contact, and even if the heights of the disc springs in the radial direction become uneven during use, the clamping force does not change. It also prevents scratches from occurring due to sharp edges.

Further, it is preferable that the sliding collar has a groove for collecting oil on the inner circumferential surface that contacts the drawbar, so that the drawbar can smoothly reciprocate in the axial direction with respect to the sliding collar, and can prevent tools, etc. Gripping force does not decrease.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on preferred embodiments shown in the drawings. FIG. 1 shows a side sectional view of a spindle clamping device for gripping a tool or workpiece pallet according to the invention. The device comprises a main shaft 2 housed within a hollow housing 1.
The main shaft 2 has bearings 3 in the front and rear regions of its outer peripheral surface.
are fitted and fixed in position by nuts 6 while being held between the collars 4 and 5, respectively.
The outer peripheral surface of this bearing 3 fits into the inner peripheral surface of the housing 1, and the front part is held by a bearing retainer 7. It will be appreciated that this configuration allows the main shaft 2 to rotate freely about the axis within the housing 1. A gear 8 is fixed to the central region of the outer peripheral surface of the main shaft 2 by a key 8', and is configured to be rotationally driven by an appropriate drive means (not shown).

The main shaft 2 has a hollow portion passing through it, and the front portion thereof forms a tapered portion 9 that widens outward. This tapered portion 9 is for receiving the rear portion of a tool 10 or a work pallet 10' (hereinafter collectively referred to as tool 10) having a conical surface that fits therein. A sleeve 12 is inserted concentrically into the hollow portion following the tapered portion 9. sleeve 1
A drawbar 11 is inserted through the hollow portion of 2 and across the rear of the main shaft 2. By fitting the large diameter portion 14 formed at the front of the drawbar 11 into the hollow portion of the sleeve 12, the nut 13 screwed into the rear portion of the drawbar 11 also fits into the hollow portion of the main shaft 2. As a result, the drawbar 11 is held concentrically inside the main shaft 2. The rear end of the sleeve 12 includes an annular wall 15 and is biased forward by a pressing force from a disc spring, which will be described later. Further, forward movement of the sleeve 12 is restricted by a step 16 on the inner circumferential wall of the main shaft 2. The front region of the drawbar 11 has a small diameter, as shown in the broken section in FIG. 1, and a collet 17 is fitted between it and the sleeve 12. This collet 17 is of a known type consisting of a member divided into two parts in the axial direction, and is positioned with its rear end 19 engaged with a groove provided in the drawbar 11.
A compression spring 18 inserted into a hole passing through 1 in the diametrical direction urges the two ends apart from each other with the rear end 19 as a fulcrum. Drawbar 11
When the collet 17 is in the position where it is drawn into the hollow part of the main shaft 2, that is, in the state shown in FIG. The tool 10 is pulled into the spindle 2 by gripping a pull stud 20 provided protruding from the rear of the tool 10 and clamped. At this position, in this embodiment, there is a gap of approximately 6 mm between the tip of the drawbar 11 and the rear end of the pull stud 20. As will be described later, when the unclamping device operates and the drawbar 11 moves forward, the collet 17 protrudes from the tip of the sleeve 12, and the claw 21 is released from the constraints of the inner peripheral surface of the sleeve 12, so the collet 17 It is configured to open using the rear end 19 as a fulcrum by the spring force of the compression spring 18, and to release the grip on the pull stud 20.

Next, a description will be given of means for providing a force for drawing the drawbar 11 into the main shaft 2. A plurality of disk springs 22 are fitted in parallel to the outer peripheral surface of the drawbar 11 in a region between the annular wall 15 of the sleeve 12 and the nut 13. The disc spring 22 exerts a pressing force on the sleeve 12 by tightening the nut 13, and the reaction force is transmitted to the nut 13, causing the drawbar 11 screwed thereto to be pushed rearward (to the right in the figure). It becomes a powerful force.

The disc spring 22 is made up of a predetermined number of sets (for example, 22 sets) each consisting of a plurality of disc springs (4 in the illustrated example) (in this example, a total of 4 x 22 = 88 pieces), and has a total weight of about 3 tons. It is designed to generate a load of . This load can be adjusted by adjusting the tightness of the nut 13, and the position of the nut 13 is fixed by a lock nut 23.

As shown in FIG. 2, the disc springs 22 are arranged so that four disc springs 22 having the same orientation are combined to form one set, and each set is such that the disc springs 22 have opposite orientations adjacent to each other. Arranged. Due to this arrangement, in sets A and B in FIG.
The disc springs 22b and 22c located at the adjacent ends of sets B and C are closest to each other in their inner peripheral regions.

Due to the pressing force of the disc spring 22, the drawbar 1
1, the tool 10 as described above.
The pull stud 20 is firmly held by the collet 17 and pulled into the spindle 2, but in order to release this and remove the tool 10 from the spindle 2,
An unclamping device described below is provided.
The device is installed in a cylinder formed by an outer wall member 25 coaxially fixed to the rear end of the housing 1 by bolts 24 and an inner wall member 26 held between the rear wall of the housing 1. , both wall members 2
A piston 27 passing through the cylinders 5 and 26 is provided to be movable in the axial direction, and the piston 27 is actuated by supplying pressurized medium into the cylinder through a pressure oil supply hole 28 bored in the outer wall member 25. It is configured. When the piston 27 is in the retracted position (the position shown in the figure), the distance between the rear end of the drawbar 11 in the clamp position and the front end of the piston 27 is set to about 5 mm. When the piston 27 moves forward, its front end contacts the rear end of the drawbar 11 and applies a pressing force of about 3.6 tons to move the drawbar 11 forward by about 7 mm. Then, the front end of the drawbar comes into contact with the pull stud 20, advances further by 1 mm, pushes the tool 10 out of the tapered portion 9, and releases the grip on the tool 10. The configuration described above is substantially the same as the prior art device, and other configurations other than those described above, such as gripping the pull stud by a ball collet, may be used.

A configuration unique to the present invention resides in the means for attaching the disc spring 22 to the drawbar 11. Second
As shown in detail in the figure, the disc spring 22 is not directly fitted to the drawbar 11;
It is fitted through a sliding collar 29 that is divided into a plurality of parts in the axial direction. In other words, drawbar 1
A sliding collar 29 is inserted between the outer peripheral surface of the spring 1 and the inner peripheral surface of the disc spring 22. In Fig. 2, the sliding collar 29a installed at the leftmost end
The sleeve 12 is provided with a flange 30a at a portion that contacts the annular wall 15 to prevent the disc spring 22 from directly contacting the sleeve 12. Also, the four disc springs 22 of the A group are attached to this sliding collar 29a.
are fitted so that their inner peripheral surfaces are in contact with each other. The sliding collar 29b next to the sliding collar 29a is formed long enough to fit the two sets of disc springs B and C, and both sets of disc springs 22 are attached to the sliding collar 29.
They are fitted in such a way that they are inclined in opposite directions with a flange 30b provided at the center of the flange 30b interposed therebetween.
Therefore, the disc springs 22b and 22c disposed at the opposing ends of both sets B and C are in contact with each side of the flange 30b without being in direct contact with each other. When the tool is in the clamped state shown in FIG. 1, that is, when the drawbar 11 is retracted into the main shaft 2, a predetermined distance is provided between the sliding collars 29a and 29b. As mentioned above, this spacing is made evenly between each sliding collar 29 so that when the drawbar 11 moves to the left in the illustrated example due to the action of the piston 27 of the unclamping device, the entire stroke can be absorbed. It is distributed.

These disc springs 22 have an inner circumferential region 31 of the disc spring 22, that is, a region close to the center thereof, in contact with the flange 30 of the sliding collar 29, and conversely, a facing contact fitted into another adjacent sliding collar 29. It is arranged so as to contact the disc spring 22 at its outer peripheral region 32, that is, an area close to the circumference of the disc spring 22.
These contacting portions 31 and 32 are formed to be flat surfaces, and are thus configured to be able to make surface contact with the other member. Furthermore, the inner circumferential surface 33 of the disc spring 22 that contacts the outer circumferential surface of the sliding collar 29 is processed so that its cross section forms an arc, so that even if a relative slip occurs between the sliding collar 29 and the disc spring 22, the disc spring 22 will not move. The edge of 22 protects the sliding collar 29 from damage. This configuration prevents damage to the drawbar due to undesired contact between the disc springs and damage to the drawbar due to sliding of the disc springs, as in the prior art described above.

Further, the sliding collar 29 is provided with an annular oil reservoir 34 on its inner peripheral surface that contacts the drawbar 11, and this is filled with a lubricant such as grease, so that the relative movement between the two members is smooth. It will be held in

FIG. 5 is a side sectional view of another embodiment, in which only one sliding collar 29 is fitted around the outer periphery of the drawbar 11, and a disc spring 22 is fitted around the outer periphery of the sliding collar 29. . An annular flange 30 is located at the center of the outer circumference of the sliding collar 29.
It is formed in places. An appropriate number of oil reservoirs 34 are provided on the inner circumferential surface of the sliding collar 29, as in the previous embodiment.
is provided to facilitate relative movement with the drawbar. In the case of this embodiment, sliding contact occurs between the disc spring 22 and the sliding collar 29, but the amount of sliding is half of that without the sliding collar 29, and there are no scratches on the outer peripheral surface of the sliding collar 29. Hard to occur. Even if a scratch occurs on the outer peripheral surface of the sliding collar 29, the drawbar 11 will not be scratched.
Only the sliding collar 29 needs to be replaced if necessary.

FIG. 6 is a side sectional view of yet another embodiment, in which a sliding collar 29 is fitted into the inner peripheral surface of the hollow part of the main shaft 2, and a disc spring 22 is fitted to the inner periphery of the sliding collar 29. It is. Slip color 2
One numeral 9 is provided for each of two sets of disc springs whose outer peripheral regions face each other. An annular flange 30 is formed on the inner circumferential surface of each sliding collar 29, and separates pairs of disk springs 22 from opposing pairs in the outer circumferential region. The inner periphery of the disc spring 22 is loosely fitted into the drawbar 11. Further, an oil reservoir 34 is formed on the outer periphery of the sliding collar 29 to facilitate relative movement between the sliding collar 29 and the inner circumferential surface of the hollow portion of the main shaft 2. Even with such a configuration, the same operation and effect as the embodiment shown in FIG. 1 can be obtained. Of course, in Figures 5 and 6, the disc springs, the disc spring and the flange, the disc spring and the sleeve 12,
As for the contact portion between the disc spring and the nut 13, it is desirable that the disc spring be formed into a flat surface.

〔Effect of the invention〕

As detailed above, according to the present invention, the disc spring for applying clamping force to the drawbar is fitted to the drawbar via the sliding collar, thereby preventing damage to the drawbar surface due to the sharp edges of the disc spring. be done. In addition, the contact parts between the disc springs and the contact parts between the disc springs and other members are formed on flat surfaces to enable surface contact at these parts, so even if the heights of the disc springs are uneven in the radial direction, Even if this happens, the clamping force remains the same, and damage to disc springs and the like is eliminated, extending the life of the parts. Due to these synergistic effects,
The conventional problem of a decrease in clamping force due to an increase in the number of clamping operations has been resolved, and a main shaft clamping device that can maintain stable clamping force for many years has been obtained.

[Brief explanation of drawings]

FIG. 1 is a side sectional view schematically showing the device of the present invention;
FIG. 2 is an enlarged side sectional view showing the fitting state of the disc spring, FIG. 3 is an enlarged side sectional view showing the fitting state of the disc spring in the conventional device, and FIG. FIG. 5 is an enlarged side sectional view showing the state of contact between the disc springs, FIG. 5 is a side sectional view showing the fitted state of the disc springs of another embodiment, and FIG. 6 is a side sectional view showing the fitted state of the disc springs of yet another embodiment. FIG. 3 is a side sectional view showing the installed state. 1...Housing, 2...Main shaft, 9...Tapered part, 10...Tool, 10'...Work pallet,
11... Drawbar, 12... Sleeve, 17...
... Collet, 20 ... Pull stud, 22 ... Belleville spring, 27 ... Piston, 29 ... Sliding collar, 30 ... Flange, 31 ... Inner peripheral area, 32
...Outer area, 34...Oil pool.

Claims (1)

[Claims] 1. A main shaft on which a tool or a workpiece pallet is attached at the tip, and a hollow part penetrating the main shaft in the axial direction, which is inserted concentrically with the main shaft, and reciprocates in the axial direction to carry the tool or workpiece. A collet that can freely engage and disengage from a pull stud protruding from the rear end of the work pallet;
is inserted into the hollow part of the main shaft concentrically with the main shaft, and the front end is attached to the rear part of the collet,
A drawbar whose rear end extends to the rear of the main shaft is provided between the outer periphery of the drawbar and the inner periphery of the hollow part of the main shaft, and a pressing force is generated between the main shaft and the drawbar to generate the a plurality of disc springs arranged to bias the drawbar backward;
and unclamping means for moving the drawbar forward against the pressing force of the disc spring until the collet is detached from the pull stud, wherein the disc spring is identical to the drawbar. A plurality of sets of disc springs are formed by stacking a plurality of disc springs in the direction of , and the sets of disc springs are arranged alternately in opposite directions. The sliding collar is fitted between the outer periphery of the drawbar and the inner periphery of the hollow part of the main shaft via at least one sliding collar that is slidable in the axial direction of the disc spring relative to the sliding collar. 1. A clamping device for a spindle, characterized in that it comprises at least one flange for locking movement. 2. The main shaft clamping device according to claim 1, wherein the sliding collar is fitted onto the outer peripheral surface of the drawbar, and the disc spring is fitted onto the outer peripheral surface of the sliding collar. 3 A plurality of the sliding collars are arranged at predetermined intervals, and at least one of them has the flange in the center, and the flange is a set of disc springs whose inner peripheral regions are arranged close to each other. 3. The main shaft clamping device according to claim 2, wherein the main shaft clamping device projects annularly from the outer circumferential surface of the sliding collar so as to separate the main shaft clamping device from the other adjacent disc spring sets. 4. The disc spring is formed as a flat surface so that an inner circumferential region that contacts the flange of the sliding collar and an outer circumferential region that faces and contacts another set of disc springs can be brought into surface contact. The main shaft clamping device described in section. 5. Any one of claims 2 to 4, wherein the sliding collar is formed with a groove for an oil reservoir on the inner circumferential surface that contacts the drawbar.
The main shaft clamping device described in section. 6. Only one sliding collar is fitted on the outer peripheral surface of the drawbar, and the flange of the sliding collar is connected to a set of disc springs whose inner peripheral regions are arranged close to each other and another disc adjacent thereto. 3. The main shaft clamping device according to claim 2, wherein the main shaft clamping device protrudes in an annular shape from the center of the outer peripheral surface of the sliding collar so as to isolate the spring set. 7. The main shaft clamping device according to claim 1, wherein the sliding collar is fitted into the inner circumferential surface of the hollow part of the main shaft, and the disc spring is fitted into the inner circumferential surface of the sliding collar.