JPS6347034A - Cutting tool clamper in spindle for machine tool - Google Patents

Abstract

PURPOSE:To eliminate any hindrance of vibration or the like caused by a lot of belleville springs used in pile, by energizing a drawbar for a pull-stud to a spindle by a belleville spring group, while using a coil spring for collet sleeve operation use. CONSTITUTION:When a cutting tool is removed from a spindle 8, a hydraulic cylinder 18 is operated, and a drawbar 7 is pushed to the front against spring force of a belleville spring group 16. In consequence, a tip member 11 presses a pull-stud 9 of the cutting tool, whereby the rear end 11b presses a collet 12, releasing a shank 4 from a taper hole 5. Next, a hydraulic cylinder 19 is operated, a collet sleeve operating rod 14 is pulled against spring force of a coil spring 17. In consequence, the pull-stud 9 is released from holding of the collet. This device is able to reduce length of the spindle 18 when using the coil spring 17, so that any hindrance of vibration or the like at high-speed rotation is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cutting tool clamping device for a main shaft of a machine tool, such as a machining center or a horizontal refmilling machine.

[Prior Art] When a cutting tool has a pull stud and is of a tapered shank type, the gripping action and pulling action of the pull stud when the cutting tool is mounted on the main shaft of a machine tool is performed by the spring force of a disc spring group. During installation, the shank is inserted into the tapered hole at the tip of the spindle, and the pull stud is gripped and pulled by the collet by the spring force of the disc spring group.
As a result, the taper shank is securely attached to the tapered hole at the tip of the spindle, and the cutting tool is securely attached to the spindle.

In addition, when removing the cutting tool from the main shaft, in order to push out the pull stud, that is, the taper shank, by the tension rod, and release the grip of the pull stud by the collet, the disc spring group is activated by other actuating means, such as a hydraulic cylinder. etc., it is compressed.

[Problems to be Solved by the Invention] When attaching and detaching a tapered shank type cutting tool having a pull stud from the main shaft of a machine tool, the pull stud is gripped by a collet and pulled by a tension rod to remove the cutting tool. A certain amount of travel of the pull rod and collet sleeve is required to seat the pull stud and then push the pull stud out of the grip of the collet and remove the cutting tool.

However, since there is a limit to the amount of deformation of a single disc spring, a large number of disc springs must be stacked and used in order to ensure a displacement greater than the predetermined amount. In order to accommodate the large number of disc springs, the length of the main shaft becomes correspondingly long.

When a main shaft using a large number of laminated disc springs is rotated at high speed, the long row of disc springs causes a so-called pure jump phenomenon, and the inner peripheral surface of the disc spring guide part and the outer peripheral edge of the disc spring The plate moved around in the gap between the two, causing the main axis to become significantly unbalanced and causing vibration.

Furthermore, a long main shaft length also increases the bearing span, leading to a reduction in critical rotation speed and causing vibration at high speed rotation.

[Means for solving the problem] A tension rod for pulling the pull stud, which has a collet for grasping the pull stud at the tip, is inserted into the main shaft on which the cutting tool of the taper shank with a pull stud is attached, and the tension rod is attached to the main shaft by a disc spring group. On the other hand, it is biased toward the rear end of the main shaft. Furthermore, a collet sleeve operating rod having a collet sleeve at its tip is inserted through the tension rod, and independently of the tension rod, a coil spring biases the main shaft toward the tip of the main shaft, so that the tension rod and the operation The rods are each provided with a hydraulic cylinder that drives the rods in a direction that opposes the spring force of the respective biasing springs.

[Function] When removing the cutting tool from the main shaft, both hydraulic cylinders are activated in sequence to compress their respective springs, and the advance of the tension rod causes the taper shank to be pushed out of the tapered hole and the collet sleeve to subsequently retreat. That is, the pull stud is released from the tension rod by expanding the collet. The cutting tool is thus removed from the spindle.

Conversely, when attaching a cutting tool to the spindle, following the previous removal operation, insert the tapered shank of the cutting tool into the tapered hole of the spindle, reverse-actuate both hydraulic cylinders one after another, and release the springs of their respective springs. The force causes the collet sleeve to move forward, that is, the pull stud is gripped by the collet, and the taper hole l\ of the taper shank is pulled in and secured by the pull rod retreat. The cutting tool is thus mounted on the spindle.

[Implementation example] Embodiments of the invention will be described with reference to the drawings.

The main shaft 3 is rotatably supported by a main shaft sleeve 1 and has a winding transmission applied to its rear end from a motor 3. The main shaft 3 has a tapered hole 5 in which a tapered shank 4 of a cutting tool is attached to the tip of the main shaft 3.
A through hole 6 is formed from the bottom of the tapered hole 5 toward the rear end.
is drilled.

A tension rod 7 is inserted into the through hole 6 so as to be freely forward and backward.

The fixing nail 8 attached at the middle step of the through hole 6 also has a center hole into which the tension rod 7 is inserted.

A collet chuck for gripping the pull stud 9 of the taper shank 4 of the cutting tool is attached to the tip of the tension rod 7.
An intermediate collar 10, which fits into the through hole 6, is fixed in the middle.

The collet chuck includes a front flange 11a and a rear flange 11 of the tip member 11 of the tension rod 7. It is composed of a collet 12 whose base portion is attached between the collet b and the collet 1 so as to be slightly movable, and a sleeve 13 fitted around the collet 12.

Tapered portions 12a2 and 13a are formed on the outer periphery of the base of the collet 12 and the inner periphery of the collet sleeve, respectively, to expand the collet 12 by acting together with the retraction of the collet sleeve.

The tension rod 7 has a tubular shape with a hollow center, and the cholera 1 to the sleeve operating rod 14 are inserted therethrough. There is a radial protrusion 15 at the tip of the collet sleeve operating rod 14, which
It protrudes from a radial slot in the pull rod 7 and is connected to the rear part of the collet sleeve 13.

Between the rear surface of the fixed nail 8 and the front surface of the intermediate collar 10, a disc spring group 16 is fitted in a stacked state onto the tension bar 7, and between the front surface of the fixed nail 8 and the rear end of the collet sleeve 13, a coil spring 1 is fitted.
7 are wound around the tension rod 7 and housed in the respective through holes 6.

At the rear of the main shaft 3, there is a hydraulic cylinder 18 for operating the tension bar for pushing the tension bar 7 forward against the spring force of the disc spring group 16, and a hydraulic cylinder 18 for operating the tension bar 14 for pushing the tension bar 7 forward against the spring force of the disc spring group 16. A hydraulic cylinder 19 for operating the collet sleeve is provided for pulling the collet sleeve backward against the spring force.

The front end surface of the piston rod of the hydraulic cylinder 18 faces the rear end surface of the tension rod 7, and the piston rod of the hydraulic cylinder I9 is inserted into a center hole drilled in the piston rod of the hydraulic cylinder 18, and is a collet sleeve operating rod. 15 with some axial play.

The operation and function of the cutting tool clamping device on the main shaft of the machine tool mentioned above will be described.

First, when removing the cutting tool from the main shaft 8 from the state where the cutting tool is attached to the main shaft 3 (the state shown in the figure), the hydraulic cylinder 18 is activated and the piston rod is moved forward. After moving forward with some play, the rear end surface of the tension rod 7 is pressed forward against the spring force of the disc spring group 16. As a result, the tip member 11 of the tension rod protrudes, and its tip surface presses the rear end surface of the pull stud 9 of the taper shank 4 of the cutting tool, and then the collar portion 11b presses the base of the collet 12, and the shank 4 The tightening of the main shaft 3 to the tapered hole 5 is released.

Next, the hydraulic cylinder 19 is operated to retract its piston rod. After retracting some play, the piston rod pulls the collet sleeve operating rod 14 backward against the spring force of the coil spring 17. As a result, the collet sleeve 13 is moved back, and the collet 12 is brought into an open state due to the joint action of the tapered portion 12a of the collet 12 and the tapered portion 13a of the collet sleeve 13, and the pull stud 9 is
The grip of cholera 1-12 is released.

In this way, the cutting tool is removed from the spindle 3.

This operation/effect is the same as the preparation stage when installing a cutting tool for the first time.

Next, in the above spindle state, the cutting tool is moved to the spindle 3.
When installing the cutting tool on the taper shank 4 of the cutting tool, first
into the tapered hole 5 of the main shaft 3.

Next, when the hydraulic cylinder 19 is activated and its piston rod is advanced to release the coil spring 17 of the collet sleeve operating rod 14, the collet sleeve 13 moves forward due to the spring force of the coil spring 17 and presses the tip of the collet 12. , the collet 12 is closed and grips the pull stud 9.

Then, operate the hydraulic cylinder 18 and screw the screws 1 to 1.
When the disc spring group 16 is released by retracting the pull rod, the tension rod 7 is moved back by the spring force of the disc spring group 16, and the tapered shank 4 of the cutting tool is firmly fixed in the tapered hole 5.

At this time, the connection is made between the tip surface of the piston rod of the hydraulic cylinder 18 in the retracted position and the rear end surface of the tension rod 7 in the retracted position, and between the piston rod of the hydraulic cylinder 19 in the forward position and the collet sleeve operating rod 14 in the forward position. There is some play in this.

For this purpose, when the main shaft 3 is driven to rotate, both non-rotating piston supports and rotating tension rod 7 and collet sleeve operating rod 14 are used.
There will be no contact failure between the two.

[Effect] In this invention, the amount of displacement of the tension bar for pulling the pull stud for pulling and tightening the taper shaft of the cutting tool into the taper hole of the spindle is small, and the pulling force is large, so the disc spring is used. However, even if the displacement of the collet sleeve to close the collet chuck for gripping the pull stud is large, the force for doing so does not need to be large, so there is no need to force the use of a disc spring group. Considering this, we decided to use coil springs for the springs for operating the collet sleeve instead of conventionally using disc springs for all springs, and configured the cutting tool clamping device accordingly. The use of multiple springs is no longer needed.

As a result, several of the drawbacks of stacking multiple disc springs as described above are eliminated.

[Brief explanation of the drawing]

The drawing is a sectional view of the main shaft of a machine tool to which a cutting tool clamping device according to an embodiment of the present invention is applied. 1: Main shaft sleeve 2: Motor 3: Main shaft 4: Tapered shank 5: Tapered hole 6: Through hole 7: Tension rod 8: Fixed nail 9 nibble stud 10: Intermediate flange 11: Tip member lLa5 front flange 11b: rear flange 12: Collet 13: Collet sleeve
12a, 13a: Tapered part 14: Collet sleeve operating rod 15: Projecting part 16: Disc spring group 17: Coil spring 18. 19: Hydraulic cylinder

Claims (1)

[Claims] On the main shaft to which a cutting tool with a taper shank with a pull stud is mounted; the pull stud traction tension rod, which is inserted through the main shaft and has a collet for grasping the pull stud at its tip, is attached to the main shaft toward the rear end of the main shaft by a group of disc springs. Forced;
A collet sleeve operating rod, which is inserted through the tension rod and has a collet sleeve at its tip, is biased toward the tip of the main shaft by a coil spring independently of the tension rod; A cutting tool clamping device in which each operating rod is provided with a device for displacing and driving the rod in a direction that resists the spring force of each biasing spring.