JP2916936B2 - Power booster for tool in spindle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power boosting apparatus for a tool in a spindle suitable for securely gripping a tool mounted in a spindle of a machine tool or the like in the spindle. .

[Related Art] Various tools are automatically exchanged and mounted in a spindle of a machine tool or the like according to a purpose of use.

Unless the tool is securely and firmly gripped in the spindle, high-precision and high-efficiency machining cannot be performed. For this reason, various gripping devices for securely clamping a tool in a spindle have been conventionally used.

Conventional gripping devices for tools generally used include:
A structure in which a drawbar connected to a collet removably engaged with a locking portion of a tool is pulled in a locking direction by a spring, and the collet is pressed against the locking portion to grip the tool to grip the tool is widely used. . Further, the disengagement between the collet and the engaging portion is performed by moving the drawbar against the reaction force of the spring by pressing means detachably engaging the rear end of the drawbar. You. In the case of the prior art, a strong spring having a large spring constant must be employed to obtain a large gripping force, and a large capacity of the pressing means is required to move the drawbar against the reaction force of the spring. Is required.

For this reason, there is also a conventional technology in which wedge action is utilized and a wedge force is exerted as the drawbar moves.

[Problem to be Solved by the Invention] As described above, a spring that generates a large gripping force causes the above-described problem,
It becomes large and expensive.
Further, those utilizing the wedge force are superior to those utilizing the spring force, but many of them have relatively complicated structures and are difficult to work. Further, there is a problem that the degree of freedom is low when setting the wedge force to a desired value.

The present invention can exert a strong gripping force, can perform high-precision processing and can easily perform processing,
Another object of the present invention is to provide a gripping device for a tool in a spindle, which has a high degree of freedom in setting a gripping force and can relatively easily set a desired gripping force.

Means for Solving the Problems In order to achieve the above object, the present invention provides a tool in a spindle which detachably engages with a tool mounted in a spindle and mounts and fixes the tool in the spindle. A collet removably engaged with a locking portion of a tool, a drawbar connected to the collet, and a collet surrounding the collet, which is fitted into the spindle and moves with the drawbar. A sleeve movably supporting the locking portion in the direction of locking or releasing with the locking portion, a locking member fixed to the rear end of the drawbar, and a tapered surface fixed to the rear end of the drawbar and inside. A piston member slidably supported in the spindle, and a plurality of locking members slidably supported in a radial direction by a closing member fixed to a rear end of the spindle. A wedge piece formed to generate a wedge force by a contact surface abutting on the tapered surface of the piston member and a locking surface locked by the locking member; and the piston member and the sleeve. A spring interposed between the spring and the urging member in a direction to press the tapered surface of the piston member toward the wedge piece, and detachably engages with a rear end of the drawbar, and presses the drawbar with a reaction force of the spring. And a pressing means for pressing against the pressure.

[Operation] A relatively weak spring mounted in the spindle When the drawbar moves backward by a constant number of springs, the collet is pushed by the sleeve and engaged with the locking portion of the tool. Because the piston member is fixed to the drawbar, the movement of the drawbar causes its tapered surface to contact the wedge piece of the closing member,
And it is pressed by the pressing force of the spring. At the same time the wedge piece is pressed against the tapered surface of the spindle member, the locking surface of the wedge piece is locked by the locking member fixed to the drawbar.
For this reason, the wedge piece is held and a wedge force is generated at the pressure contact portion with the tapered surface of the piston member. This results in a large gripping force. Further, since a plurality of wedge pieces are arranged along the inner periphery of the closing member and the sliding direction thereof is along the radial direction of the closing member, the working can be performed easily and with high precision.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the booster gripping device according to the present embodiment includes a piston member 1, a wedge piece 2, a locking member 3, a closing member 4, and the like. First, the entire tool gripping structure will be described.

The spindle 5 is pivotally supported by a headstock 6 via bearings 7, 8 and the like, and is rotationally driven by a drive mechanism (not shown). A tool 10 provided with a pull stud 9 on the rear end side is mounted on the front end side (left end in the figure) of the spindle 5. A sleeve 12 is fitted into the inner hole 11 of the spindle 5, and a tapered portion 13 whose diameter increases toward the distal end is formed at the distal end of the sleeve 12. sleeve
The collet 14 is accommodated in the inside 12, and the locking portion 15 of the collet 14 is locked to the locking portion 16 of the pull stud 9. In addition, a tapered portion 17 is formed on the outer periphery of the collet 14 near the tapered portion 13 of the sleeve 12 so as to increase its diameter toward the distal end. The locking portion 15 of the collet 14 is the locking portion 16 of the pull stud 9.
The outer periphery of the collet 14 is
To prevent the collet 14 from opening outward.

A drawbar 18 is connected to the collet 14. The drawbar 18 is guided by a guide hole of the sleeve 12 fitted into the inner hole 11 of the spindle 5, extends toward the rear portion, and
Are arranged along the axis of.

The piston member 1 is fixed to the rear end side of the drawbar 18, and the contact member 3 is screwed and fixed. The contact member 3 has a locking portion (step) 19 protruding from the outer periphery of the drawbar 18.
Is formed.

Inside the piston member 1 is formed a tapered surface 20 whose diameter increases toward the rear side of the spindle 5. The closing member 4 is fixed to a rear end portion of the spindle 5, and has a tapered portion 21 having a diameter smaller than a tapered surface 20 of the spindle member 1 at a front end side of the closing member 4. Further, a through hole 22 is formed through which the locking member 3 can be inserted when the drawbar 18 moves rearward.

 Next, the wedge piece 2 will be described.

FIG. 2 is an enlarged sectional view taken along the line II-II of FIG. 1 with the spindle member 1 removed. In addition, since FIG. 1 is a sectional view taken along the line II of FIG. 2, only one wedge piece 2 is displayed in FIG.

The wedge piece is formed of a pin-like body slidably supported in a guide hole formed in the tapered portion 21 of the closing member 4 along its radial direction. In this embodiment, as shown in FIG. 3
Are arranged at equal intervals in the circumferential direction. An arc-shaped abutting portion 23 is formed on the head of the piston member 1 to abut against the tapered surface 20 of the piston member 1 and a locking surface 24 inclined along the axial direction thereof.
Is formed. As shown in FIG. 3, a spring 25 having one end fixed to the closing member 4 engages the other end of the wedge piece 2 and presses the wedge piece 2 outward. Needless to say, the spring 25 prevents the wedge piece 2 from protruding from the locking member 4.

A relatively weak spring constant spring 26 is interposed between the sleeve 12 and the piston member 1 in the inner hole 11 of the spindle 5.

At the rear end of the spindle 5 is a cylinder body of the pressing means 27
28 is fixed. The cylinder body 28 communicates with a working medium source (not shown) and slidably supports the piston 29. Piston 29
The rod 30 is disposed so as to face the rear end portion of the drawbar 18, and acts to contact the drawbar 18 and move the drawbar 18 forward when releasing the locking of the collet 14.

 Next, the operation of the present embodiment will be described.

When the pressing means 27 is operated and the tool 10 is inserted into the spindle with the locking portion 15 of the collet 14 opened, the operation of the pressing means 27 is stopped. By pressing force of spindle 5,
The draw bar 18 moves rearward through the piston member 1, and the engaging portion 15 of the collet 14 is engaged with the engaging portion of the pull stud 9 of the tool 10.
The tool 10 is engaged, and the tool 10 is gripped. In this state, as shown in FIG. 3, the tapered surface 20 of the piston member 1 comes into contact with the arcuate contact portion 18 of the wedge piece 2 and lowers the wedge piece 2 against the reaction force of the spring 25. At this position, the locking surface 24 of the wedge piece 2
19 comes into contact with the locking surface 24, and the wedge piece 2 is fixed. Therefore,
A large wedge force is generated between the arc-shaped contact portion 18 of the wedge piece 2 and the tapered surface 20 and between the locking surface 24 of the member 2 and the contact surface of the member 3 to generate a large wedge force. And a force is generated that firmly holds the drawbar 18 in place. Therefore, the collet 14 clamps the tool 10 with a large gripping force. The force generated between the tapered surface 20 of the piston member 1 and the arcuate contact portion 18 of the wedge piece 2 is a force acting along the axial direction of the drawbar 18, that is, several times to several tens of the pressing force by the spring 26. Since the force is doubled, a large gripping force can be exerted by an extremely small axial force.

To release the gripping of the tool 10 by the collet 14, the pressing means 27 is operated, the rod 30 is brought into contact with the rear end of the drawbar 18, and the drawbar 18 is moved to the above against the reaction force of the spring 26, The tapered portion 17 of the collet 14 advances to a position where it coincides with the tapered surface 13 of the sleeve 12, the collet 14 is opened outward, the lock with the locking portion 16 is released, and the tool 10 can be pulled out. Hereinafter, insertion and removal of the tool 10 are performed by repeating the same operation as described above.

As shown in FIG. 2, a wedge force is generated for each of the wedge pieces 2, and the wedge forces are compared based on the shape of the tapered surface 20 of the piston member 1, the head shape of the wedge piece 2, the spring force of the spring 26, and the like. Is easily calculated.

On the other hand, the processing of the tapered surface of the piston member 1 and the processing of the pin-shaped wedge piece 2 and the guide hole of the locking member 4 supporting the wedge piece 2 are relatively easily and accurately performed by ordinary machining. Since it can be performed, a boosted gripping device having a desired gripping force can be formed with high precision and easily at low cost.

In the present embodiment, the shapes of the piston member 1, the wedge piece 2 and the like are shown in the figure, and the number of the wedge pieces 2 is six.
It is not limited to them.

According to the present invention, the following remarkable effects are obtained.

1) A relatively simple piston member, wedge piece, etc.
A large wedge force can be generated, and a large tool gripping force can be generated.

2) Even if the pressing force of the spring that presses the piston member in the axial direction is small, a large gripping force can be obtained, so that the spring may have a low spring constant and the pressing means may have a small capacity. Therefore, it is small and inexpensive.

3) The overall length of the spindle can be shortened because the overall length of the spring and the like is reduced and the pressing means is also reduced in size. Therefore, it is possible to process and support the spindle with higher precision.

4) By appropriately setting the shape of the tapered surface of the piston member, the shape and the number of wedge pieces, a booster gripping device having a desired gripping force can be formed.

5) Since each component of the booster gripping device can be processed relatively easily and with high precision, a booster gripping device having reliability and stability can be manufactured.

[Brief description of the drawings]

1 is an axial sectional view of one embodiment of the present invention, FIG. 2 is an enlarged axial sectional view taken along line II-II of FIG. 1, and FIG. 3 is an enlarged axial sectional view for explaining the operation of the embodiment. is there. 1 ... piston member, 2 ... wedge piece, 3 ... locking member, 4
... closing member, 5 ... spindle, 6 ... headstock, 7, 8
… Bearing, 9… Pull stud, 10… Tool, 11… Inner bore, 12… Sleeve, 13, 17, 21… Taper, 14… Collet, 15, 16, 19… Locking Department, 18 ... Drawbar, 20 ...
Taper surface, 22 ... Through hole, 23 ... Arc-shaped contact portion, 24 ... Locking surface, 25 ... Spring, 26 ... Spring, 27 ... Pressing means, 28 ... Cylinder body, 29 ... Piston , 30 ... rod.

Claims (1)

(57) [Claims] 1. A tool gripping device in a spindle which detachably engages a tool mounted in a spindle and mounts and fixes the tool in the spindle, detachably engages with a locking portion of the tool. A collet, a drawbar connected to the collet, and a supporter which is fitted in the spindle so as to surround the collet and is movably supported in a direction to lock or release the collet with the locking portion as the drawbar moves. A sleeve member, a locking member fixed to the rear end side of the drawbar, a piston member fixed to the rear end side of the drawbar, forming a tapered surface therein and slidably supported in the spindle. A plurality of locking members slidably supported along a radial direction by a closing member fixed to a rear end of the spindle, and abutting on the tapered surface of the piston member. A wedge piece formed to generate a wedge force by a contact surface and a locking surface for locking to the locking member; and a taper surface of the piston member interposed between the piston member and the sleeve, the wedge being formed by the wedge. It is characterized in that a spring is provided which urges in the direction of pressing to the piece side, and pressing means which is detachably engaged with the rear end of the drawbar and presses the drawbar against the reaction force of the spring. A tool for gripping the tool in the spindle.