JPH0760516A - Boring device - Google Patents

Abstract

PURPOSE:To reduce required space, prevent deterioration of protruding precision of a cutting tool by thermal effects at the time of high speed rotation of a main spindle, and secure work precision by restricting vibration of the main spindle at the time of high speed rotation in a boring device. CONSTITUTION:A forward end part 33a of a cutting tool holder 33 provided with a cutting tool 34 at a forward end of a main spindle 31 is held to be capable of displacement in the radial direction through a resilient support member 35, a piston 38 provided inside a forward end part of the main spindle 31 to be movable to advance and retract in the radial direction is applied to a side surface which is parallel to a main spindle axis at a back end part 33b of the cutting tool holder 33, and pressure is generated by oil enclosed in an oil chamber 39 connected to a back surface of the piston 38 by a piezo-actuator 36. The back end part 33b of the cutting tool holder 33 is pushed by the piston 38, and the forward end part 33a of the cutting tool holder 33 is radially displaced about the resilient support member 35 as a support point for protruding the cutting tool 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boring machine for boring a workpiece.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional general boring device is rotatably supported by a headstock 1 and has one end fixed with a bolt 5 to the tip of a main shaft 2 which is driven to rotate by a built-in motor 3. A tool 6 provided on a tool holder 4 which is elastically displaceable in the radial direction, and an inclined cam 8 formed at the tip of an operating shaft 9 which is axially movably penetrated by the shaft center of the main shaft 2 and which rotates integrally with the main shaft by a key 10. The tool holder 4 is connected to the tool holder 4 via a pin 7, and the forward movement of the operating shaft 9 causes the tool holder 4 to be radially displaced via the inclined cam 8 and the pin 7 so that the cutting tool 6 is pushed out. There is.

The shaft moving device for the working shaft 9 which rotates integrally with the main shaft 2 has the structure shown in FIG. 4 provided at the rear end of the main shaft 2 in FIG. That is, a support base 1 separate from the headstock 1
The cylindrical body 13 is fixed to the bearing member 12 fixed to 1 by a key 14 in the rotational direction and is provided slidably in the axial direction. The rear end of the operating shaft 9 is axially provided in the front end portion of the cylindrical body 13. The nuts 18 are engaged with each other and are rotatably supported by a bearing 15 so as to be connected to each other, and a nut 18 screwed into a ball screw 16 is fixed to a rear end portion of the cylindrical body 13. The nut 18 is inserted by rotation of the ball screw 16. The cylindrical body 13 is moved forward and backward to move the operating shaft 9 forward and backward.

The ball screw 16 is supported by the bearing member 12 via a bearing 17 and is connected to a servomotor 19 mounted at the rear end of the bearing member 12.

[0005]

In the boring machine of the above-mentioned structure, the ball screw 16 for pushing out the cutting tool 6 is installed on the support base 11 which is separate from the headstock 1, so that the operating shaft 9 There is a deviation of the axial center between the cylinder body 13 and the cylinder body 13. As a result, when the main spindle 2 is rotated at a high speed, the vibration force of the main spindle 2 increases, and there is a problem that the machining accuracy cannot be obtained. Further, due to the displacement of the shaft core, the bearing 15 supporting the rear end of the operating shaft 9 generates a large amount of heat, and the thermal expansion of the operating shaft 9 causes the position of the cutting edge to change, resulting in unstable machining accuracy. There was a problem. Further, since the mechanism for pushing out the cutting tool 6 is linkedly arranged at the rear end of the main shaft 2, there is a problem that the total length is long.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is characterized by a main shaft which is rotatably supported by a headstock and rotationally driven by a motor. A bite holder that is always held in a concentric position with the main shaft via an elastic support member at the tip, and is displaced in the radial direction with the elastic support member as a fulcrum to push out the cutting tool attached to the tip, and a piezo actuator. And a transmission mechanism that converts the operation of the piezo actuator into a radial movement of the main shaft and is capable of contacting the rear end of the bite holder.

[0007]

With the above construction, the radial momentum of the main shaft increases in proportion to the applied voltage of the piezo actuator, and the rear end of the tool holder is pushed by the transmission mechanism to use the elastic support member as a fulcrum to support the tool holder. Displace the tip of the tool in the radial direction and push out the cutting tool. When the voltage applied to the piezo actuator is turned off, the bite holder is returned to the position concentric with the main shaft by the elastic restoring force of the elastic support member.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 30 is a headstock, 31 is the headstock 3
It is a main shaft rotatably supported at 0. Reference numeral 32 denotes a built-in motor arranged at the rear end of the main shaft 31, which drives the main shaft 31 to rotate.

A bite holder 33 has a cutting tool 34 attached to a shaft portion 33a at the tip thereof and has a rear end portion 33b having a side surface parallel to the axis of the spindle. The bite holder 33 is always held by the elastic support member 35 fixed to the tip of the main shaft 31 at a position concentric with the main shaft 31, and is displaceable in the radial direction with the portion A excluding the slit 35a as a fulcrum. Has been. The elastic support member 35 is a donut collar-shaped member made of metal and provided with slits 35a from both sides in the diametrical direction.

A cylinder member 45 and a piezo actuator 36 are arranged in series in the axial direction in the main shaft 31 of the rear end portion 33b of the bite holder 33.
Reference numeral 5 denotes a piston 38 that is in contact with a side surface of the rear end portion 33b of the bite holder 33 that is parallel to the main axis, and that is movable forward and backward in the radial direction, and oil that is filled with oil and communicates with the rear surface of the piston 38. And chamber 39. A piston 3 for generating pressure on the oil enclosed in the oil chamber 39 is provided at the front end of the piezo actuator 36.
7 is provided. The diameter of the piston 37 is larger than the diameter of the piston 38, so that the piston 38 can obtain a larger stroke than the piston 37. The pistons 37, 38 and the oil chamber 39 constitute a transmission mechanism that converts the operation of the piezo actuator 36 into a radial movement of the main shaft. As another example, the transmission mechanism may be a lever having a dogleg shape pivoting around an axis orthogonal to the main shaft rotation axis.

The wiring for applying a voltage to the piezo actuator 36 arranged at the tip of the main shaft 31 passes through a hole penetrating the shaft center of the main shaft 31, and a slip ring 40 is provided at the rear end of the main shaft 31. It is electrically connected to external wiring. Reference numeral 41 represents an encoder.

FIG. 2 shows another embodiment of the present invention. In the other embodiment, a piezo actuator 36 and a piston 37 that moves back and forth by the piezo actuator 36 are arranged outside the main shaft 31, and an oil whose one end is formed in the cylinder member 45 at the shaft center of the main shaft 31. An oil passage 42 that communicates with the chamber 39 is provided, and the other end of this oil passage 42 communicates with a mechanical seal 44 provided at the rear end of the main shaft 31, and the piezoelectric actuator 3 is connected via this mechanical seal 44.
This is a structure in which the front surface of the piston 37 of FIG. Since this does not have the slip ring 40 of FIG. 1, there is no risk of electric leakage.

In the configuration of FIG. 1 described above, when no pressure is generated in the oil enclosed in the oil chamber 39, the bite holder 33 held by the elastic supporting member 35 is caused by the spring action of the elastic supporting member 35. It is located concentrically with the main shaft 31.

A voltage is applied to the piezo actuator 36 to project the cutting tool 34. As a result, the piston 37 at the front end of the piezo actuator 36 moves forward and the oil chamber 3
Pressure is generated in the oil enclosed in 9.

Due to the hydraulic pressure generated in the oil chamber 39, the piston 38, which is in contact with the side surface of the rear end portion 33b of the bite holder 33 parallel to the spindle axis, is advanced to push the rear end portion 33b of the bite holder 33. . By pushing the rear end 33b of the bite holder 33, the tip 33a of the bite holder 33 is displaced in the radial direction with the elastic support member 35 as a fulcrum, and the blade 34
Stick out.

The amount of protrusion of the cutting tool 34 is controlled by adjusting the voltage applied to the piezo actuator 36. That is, as the voltage applied to the piezo actuator 36 increases, the forward displacement amount of the piston 37 increases, and accordingly, the forward movement amount of the piston 38 that pushes the rear end portion 33b of the bite holder 33 increases. As a result, the amount of radial displacement of the tip portion 33a of the bite holder 33 increases, and the protruding position of the cutting tool 34 increases in proportion to the voltage applied to the piezo actuator 36. Therefore, the voltage applied to the piezo actuator 36 is adjusted and set according to the hole machining diameter to control the appropriate protruding position of the cutting tool 34.

When the voltage applied to the piezo actuator 36 is cut off, the volume of the oil chamber 39 increases and the pressure of the oil in the oil chamber 39 drops. The elastic restoring force of the elastic supporting member 35 causes the bite holder. The piston 38 pushing the rear end portion 33b of 33 is pushed back in the backward direction, the piston 37 is moved backward, and the bite holder 33 is returned to the position concentric with the main shaft 31.

In another embodiment shown in FIG. 2, the forward movement of the piston 37 by the piezo actuator 36 arranged outside the main shaft 31 causes the pipe 43 and the shaft center of the main shaft 31 communicating with the pipe 43 via the mechanical seal 44. The oil in the oil passage 42 is moved to generate a pressure in the oil enclosed in the oil chamber 39, and the blade 34 is pushed out in the same manner as described above. In this case, it becomes easy to arrange the electric wiring to the piezo actuator 36 arranged outside the spindle 31.

[0019]

As described above, according to the present invention, the tip end of the bite holder provided with a cutting tool at the tip of the spindle is held by an elastic support member so as to be displaceable in the radial direction, and the spindle is provided by a piezo actuator and a transmission mechanism. Of the cutting tool, the rear end of the cutting tool holder is pushed, and the tip of the cutting tool holder is displaced in the radial direction with the elastic supporting member as a fulcrum, so that the cutting tool is pushed out. Therefore, unlike the conventional case, the servomotor, the ball screw, the actuating shaft and the rotating shaft bearing for generating heat which are required in the rear of the main spindle are not required, so that it is possible to save space and prevent the accuracy of the protrusion of the cutting tool from being lowered due to the thermal displacement of the main spindle at high speed. Further, since there is no misalignment of the shaft core, the vibration of the main shaft is small even when the main shaft is rotated at high speed, and the machining accuracy is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of the device of the present invention.

FIG. 2 is a sectional view showing another embodiment of the device of the present invention.

FIG. 3 is a sectional view of a front half of a spindle of a conventional device.

FIG. 4 is a sectional view of the latter half of the main shaft of a conventional device.

[Explanation of symbols]

 30 Headstock 31 Main spindle 32 Built-in motor 33 Tool holder 34 Cutting tool 35 Elastic support member 36 Piezo actuator 37 Piston 38 Piston 39 Oil chamber

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuhiro Nagasawa 1-1, Asahi-cho, Kariya city, Aichi prefecture Toyota Koki Co., Ltd.

Claims (1)

[Claims] 1. A main shaft that is rotatably supported by a headstock and is rotationally driven by a motor, and an elastic supporting member at the tip of the main shaft, which is always held in a concentric position with the main shaft, and the elastic supporting member is a fulcrum. And the tool holder that displaces in the radial direction and pushes out the cutting tool attached to the tip, the piezo actuator, and converts the operation of this piezo actuator into the radial movement of the main spindle, and applies it to the rear end of the tool holder. A boring device having a transmission mechanism capable of contacting.