JPH0647602A - Main shaft device - Google Patents

Abstract

PURPOSE:To prevent a tool holder from slipping out of a main shaft even in the case when cylinder pressure for clamping the tool holder to the main shaft decreases or comes to zero, as well as suppressing vibration of the main shaft in high speed rotation. CONSTITUTION:A clamp rod 12 which is supported by being inserted in a main shaft 2 is moved forward and backward by means of a cylinder 16 and a piston 17 for clamping or unclamping a tool holder to or from the main shaft 2. The main shaft 2 is rotated by means of a driving motor 6 by keeping the tool holder clamped. Channels 24 and 25 extending radially are formed on the internal circumferential face of the cylinder 16 and on the outer circumferential face of the piston 17 respectively for housing movably locking bodies 26 therein. A static pressure coupling is prepared between the main shaft 2 and a motor shaft 10 for transmitting torque through a pressure fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle device for machine tools.

[0002]

2. Description of the Related Art Conventionally, in a spindle device of a machine tool,
A spindle is rotatably supported by the spindle head, a tool holder is removably mounted in a holding hole at the tip of the spindle, and a clamp rod is movably inserted and supported in the spindle. An overlapping disc spring is provided in the main shaft, and normally the disc spring urges the clamp rod to move in the clamping direction to clamp the tool holder. Also, when the clamp rod is moved against the biasing force of the disc spring,
The tool holder is designed to be unclamped.

However, in recent years, the rotational speed of the main shaft has been increased by improving the bearings and the lubricating means. However, as described above, when the main disc is provided with the overlapping disc spring, which tends to cause an unbalanced state, Due to the unbalanced state of the disc spring, vibration easily occurs when the spindle rotates at high speed. Therefore, there is a problem that the upper limit of the rotation speed of the main shaft is limited to a range where vibration does not occur.

In order to solve such a problem, a cylinder is provided at the base end portion of the main shaft instead of the lap disc spring, and the clamp rod is moved forward and backward by the piston in the cylinder to clamp and clamp the tool holder. It is possible to unclamp.

[0005]

However, in such a structure, when the supply of the pressure fluid to the cylinder is stopped or the pressure of the pressure fluid is reduced, the clamping force necessary for clamping the tool holder is applied to the cylinder. Cannot be secured by. For this reason, the tool holder comes out of the holding hole of the main shaft, and there is a problem that the tool holder comes off during a high-speed rotation, leading to a serious accident.

Further, in the conventional spindle device, the motor shaft of the drive motor is connected to the base end of the spindle via the shaft joint. For this reason, even if the overlapping disc spring is omitted as described above and the occurrence of vibration due to the unbalanced state is suppressed, the vibration during high-speed rotation of the drive motor is transmitted from the motor shaft to the main shaft via the shaft coupling. There is a problem that it is directly transmitted and high rotation accuracy cannot be obtained.

The present invention has been made by paying attention to the problems existing in such a conventional technique, and the purpose thereof is to suppress the vibration of the spindle at high speed rotation,
High rotation accuracy can be ensured, and even if the pressure of the cylinder for clamping the tool holder on the spindle decreases or becomes zero, the tool holder does not disengage from the spindle and the tool holder falls off, which is a serious problem. An object of the present invention is to provide a spindle device that can prevent an accident from occurring.

[0008]

In order to achieve the above object, in the invention described in claim 1, the main spindle is rotatably supported by the main spindle head, and the motor shaft of the drive motor is the base end of the main spindle. In the main spindle device, a tool holder is detachably attached to the holding hole at the tip of the main spindle, and a clamp rod for clamping and unclamping the tool holder is inserted into the main spindle so as to be movable back and forth. A cylinder is provided at the base end of the main shaft, a piston accommodated in the cylinder is provided at the base end of the clamp rod, and the clamp rod moves in the unclamp direction between the cylinder and the piston when the main shaft rotates. An unclamping prevention mechanism for preventing the above is provided, and the main shaft and the motor shaft are connected via a static pressure coupling that transmits a rotational force via a pressure fluid.

According to the second aspect of the invention, a fluid supply passage for branching and supplying the pressure fluid to the cylinder and the static pressure coupling is provided in the main spindle head.

[0010]

In the spindle device configured as described above, when the pressure fluid is supplied into the cylinder with the tool holder mounted in the holding hole of the spindle, the clamp rod is moved in the clamping direction to move the tool. The holder is clamped on the spindle. When the drive motor is rotated in this state, the main shaft is rotationally driven via the static pressure coupling, and the tool holder is rotated at high speed. At this time, for example, the locking body of the unclamping prevention mechanism is positioned between the piston and the cylinder by the centrifugal force.

Therefore, even if the pressure of the cylinder is reduced or becomes zero due to a stop of the pressure fluid supply device or a leak in the pressure fluid piping system, the tool holder can be disengaged from the spindle. Moreover, it is possible to prevent the possibility of a serious accident due to the tool holder falling off.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spindle device embodying the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 2, the main spindle head 1 is formed in a hollow cylindrical shape, and a cylindrical main spindle 2 is rotatably supported in the interior thereof through a plurality of bearings 3. A tapered holding hole 4 is formed at the tip of the main shaft 2, and a tool holder 5 is detachably attached to the holding hole 4. The drive motor 6 is mounted on the spindle head 1 and is composed of a motor casing 7, a stator 8, a rotor 9 and a motor shaft 10.
The static pressure coupling 11 is provided between the opposed ends of the motor shaft 10 and the main shaft 2, and the rotation of the motor shaft 10 is transmitted to the main shaft 2 via the static pressure coupling 11.

The clamp rod 12 is inserted and supported in the main shaft 2 so as to be movable back and forth, and a pull stud type clamp mechanism 13 is provided between the tip of the clamp rod 12 and the tool holder 5. The clamp mechanism 13 has a plurality of clamp balls 14 housed in the support holes of the clamp rod 12 and a pull stud 15 provided at the base end of the tool holder 5 so as to engage with the clamp balls 14. There is.

With the clamp ball 14 of the clamp mechanism 13 engaged with the pull stud 15, the clamp rod 12 is pulled upward in the drawing in the clamping direction, so that the tool holder 5 is inserted into the holding hole 4 of the spindle 2. It is clamped in the installed state. Further, when the clamp rod 12 is moved downward in the drawing in the unclamping direction, the clamp ball 14 is separated from the pull stud 15, and the tool holder 5 is released from the clamped state.

As shown in FIGS. 1 to 5, the clamp cylinder 16 is integrally formed at the base end of the main shaft 2 and has an upper surface opened. The clamp piston 17 is formed integrally with the base end of the clamp rod 12 so as to be housed in the cylinder 16, and a guide hole 18 is formed at the center thereof. The guide rod 19 is provided so as to project from the lower end of the motor shaft 10 and is fitted in the guide hole 18 of the clamp rod 12 so as to be relatively movable.

As shown in FIGS. 1 to 3, the fluid supply path 20.
Is formed so as to penetrate through the centers of the motor shaft 10 and the guide rod 19. The branch supply path 21 is the clamp rod 12
And is connected to the fluid supply passage 20. The fluid supply port 22 is attached to the upper portion of the motor casing 7, and one end thereof is connected to the fluid supply passage 20 of the motor shaft 10. When a pressure fluid such as air or oil is supplied from the pressure fluid supply device (not shown) to the fluid supply passage 20 through the fluid supply port 22, the pressure fluid passes through the branch supply passage 21 and is used as a clamping cylinder. 1
6 is introduced into the pressure chamber 23. As a result, the clamp piston 17 is pushed up and the clamp rod 12
Is urged to move in the clamping direction.

As shown in FIGS. 1 and 4, a pair of vertical grooves 2
Reference numerals 4 are formed at equal intervals on the inner peripheral surface of the clamping cylinder 16, extend parallel to the axial direction, and have a slanted bottom surface. The pair of lateral grooves 25 are formed obliquely at equal intervals on the outer peripheral surface of the clamping piston 17, and the outer ends thereof are connected to the vertical grooves 24. The locking body 26 formed of a pair of spheres is housed in the grooves 24 and 25 so as to be movable in the radial direction, and when the main shaft 2 is rotated at a high speed by the drive motor 6, the locking body 26 is formed. Is displaced radially outward along. The both grooves 24, 25 and the locking body 26 constitute an unclamping prevention mechanism.

A pair of stop screws 27 are adjustably screwed to the clamp rod 12, and the tips of the stop screws 27 project into the vertical groove 24 so that the piston 17 is moved to the cylinder 1.
It has been stopped against 6. Then, as described above, when the locking body 26 is moved to the outer ends of the grooves 24, 25 with the rotation of the main shaft 2, the tip of the stop screw 27 has a predetermined gap that is adjusted and set. It corresponds to the proximity of 26. Therefore, the pressure fluid supply device may stop, or a leak may occur in the pressure fluid piping system,
Even when the internal pressure of the cylinder 16 drops or becomes zero, the engagement of the locking body 26 and the stop screw 27 restricts the movement of the clamp rod 12 in the unclamping direction.

As shown in FIGS. 1 to 5, the concave portion 28 of the static pressure coupling 11 is formed on the end face of the clamp piston 17 at the base end of the main shaft 2 and extends in the radial direction at a position orthogonal to the vertical groove 24. It is extended. The convex portion 29 is attached to the lower end of the motor shaft 10 by a nut 30 so as to extend in the radial direction, and is fitted in the concave portion 28 with a predetermined gap. The hydrostatic bearing 31 has a concave portion 28 and a convex portion 29 facing each other.
A branch supply passage 32 is formed in the convex portion 29 so as to communicate with the static pressure bearing 31. Then, the pressure fluid is supplied from the fluid supply path 20 to the hydrostatic bearing 31 via the branch supply path 32, and the hydrostatic bearing 3
From the motor shaft 10 to the main shaft 2 through one layer of pressure fluid
The rotational force is transmitted to.

A pair of substantially half-moon-shaped pressed portions 34 are formed on the end surface of the piston 17 on both sides of a recess 33 formed on the end surface of the clamping piston 17 for fitting the convex portion 29. . The unclamping cylinder 35 is formed inside the spindle head 1 by the partition 36 so as to be located outside the clamping cylinder 16. The unclamping piston 37 is movably accommodated in the unclamping cylinder 35, and a pair of pressing pieces 38 is provided at the upper end of the unclamping piston 37 so as to be engaged with the pressed portion 34 of the clamping piston 17.

The first supply port 39 is formed in the spindle head 1 and the partition 36 and communicates with the lower pressure chamber 40 in the unclamping cylinder 35. Then, when the pressure fluid is supplied from the first supply port 39 to the lower pressure chamber 40, the unclamping piston 37 is normally pushed up and the pressing piece 38 is held at a position separated from the pressed portion 34. ing. The second supply port 41 is formed in the motor casing 7 and communicates with the upper pressure chamber 42 in the unclamping cylinder 35. Then, when the main shaft 2 is stopped, pressure fluid is supplied from the second supply port 41 to the upper pressure chamber 42, so that the unclamping piston 37 is pushed down. As a result, the pressing piece 38 engages with the pressed portion 34, and the clamp rod 12 is moved in the unclamping direction.

As shown in FIGS. 2 and 3, a pair of detected bodies 43 made of magnets are attached to the outer periphery of the lower end of the motor shaft 10 at equal intervals. The magnetic sensor 44 is disposed in the motor casing 7 and corresponds to the detected body 43 in proximity. Then, when the drive motor 6 is stopped, based on the detection of the detected body 43 by the magnetic sensor 44, the pressed portion 34 on the clamping piston 17 corresponds to the pressing piece 38, and the main shaft 2 moves. The rotation is set to stop.

Next, the operation of the spindle device constructed as described above will be described. Now, when the pressure fluid is supplied from the supply device (not shown) to the fluid supply path 20 through the fluid supply port body 22 with the tool holder 5 mounted in the holding hole 4 of the main shaft 2, the pressure fluid is branched into the branch supply path. It is introduced into the pressure chamber 23 of the clamping cylinder 16 via 21. Thereby, the clamp piston 17 is pushed up,
The clamp rod 12 is moved upward in the clamp direction,
The tool holder 5 is clamped on the spindle 2 by the clamp mechanism 13. The pressure fluid in the fluid supply passage 20 is also introduced into the static pressure bearing 31 of the static pressure coupling 11 via the branch supply passage 32. In addition, the pressure fluid is supplied to the lower pressure chamber 40 of the unclamping cylinder 35, and the pressing piece 38 of the unclamping piston 37 has the pressing piece 38.
4 is moved in the direction away from 4.

When the drive motor 6 is rotated in this state, the spindle 2 is rotationally driven via the static pressure bearing 31 of the static pressure coupling 11, and the tool holder 5 is rotated at high speed. At this time, the locking body 26 is displaced radially outward between the clamping piston 17 and the cylinder 16 along the grooves 24 and 25 by the centrifugal force, and a predetermined gap is provided at the tip of the stop screw 27. And respond in close proximity. Therefore, even if the internal pressure of the cylinder 16 decreases or becomes zero due to the pressure fluid supply device stopping or the pressure fluid piping system leaking, the locking body 26 and the stop screw 27 are stopped. With the engagement with, the movement of the clamp rod 12 in the unclamping direction is restricted. Therefore, the tool holder 5 does not come off from the holding hole 4 of the spindle 2, and the tool holder 5
It is possible to prevent the possibility of a serious accident due to the loss of the car.

When the tool holder 5 is replaced after the predetermined processing is performed by the rotation of the tool holder 5, the rotation of the drive motor 6 is stopped and the fluid supply passage 2 is
The supply of pressurized fluid to 0 is stopped. At this time, based on the detection of the detected body 43 by the magnetic sensor 44, the rotation of the spindle 2 is stopped at the position where the pressed portion 34 on the clamping piston 17 corresponds to the pressing piece 38. Then, in this state, the unclamping cylinder 35 is fed from the second supply port 41.
The pressure fluid is supplied to the upper pressure chamber 42 of the unclamping piston 37 and the unclamping piston 37 is pushed down. As a result, the pressing piece 38 engages with the pressed portion 34, and the clamp rod 12
Is moved downward in the unclamping direction, and the tool holder 5 is released from the clamped state by the clamp mechanism 13.

Further, in the spindle device of this embodiment,
As a means for moving the clamp rod 12 in the clamp direction, a clamp cylinder 16 and a piston 17 are provided without using a lap disc spring. Therefore, when the main shaft 2 rotates at high speed, there is no possibility that vibration will occur due to the unbalanced state of the disc spring. Further, in the spindle device of this embodiment, the rotational force is transmitted from the motor shaft 10 of the drive motor 6 to the spindle 2 via the static pressure bearing 31 of the static pressure coupling 11. for that reason,
Vibration of the drive motor 6 during high-speed rotation is not directly transmitted from the motor shaft 10 to the main shaft 2, and a high rotation accuracy can be obtained in combination with the above vibration suppression effect.

In addition, in the spindle device of this embodiment, one fluid supply passage 20 is provided at the center of the motor shaft 10 and the guide rod 19, and the pressure fluid supplied to the fluid supply passage 20 is a branch supply passage. It is adapted to be introduced into the clamp cylinder 16 and the static pressure bearing 31 through 21 and 32. Therefore, the structure for supplying the pressurized fluid to the cylinder 16 and the hydrostatic bearing 31 can be simplified.

The present invention is not limited to the configuration of the above-described embodiment, but can be modified and embodied as follows without departing from the spirit of the present invention. (1) The clamp cylinder 16 is formed separately from the main shaft 2 and is fixed to the base end of the main shaft 2. (2) The clamp piston 17 is not formed integrally with the clamp rod 12 but is formed separately and is fixed to the base end of the clamp rod 12. (3) Contrary to the above embodiment, the concave portion 28 of the static pressure coupling 11 is provided on the motor shaft 10 side, and the convex portion 29 is provided on the main shaft 2 side. (4) As the clamp mechanism 13 of the tool holder 5, a collet chuck type is used instead of the pull stud type of the above-mentioned embodiment. (5) The present invention is embodied in a horizontal (horizontal) spindle device in addition to the vertical (vertical) spindle device of the above embodiment.

[0030]

Since the present invention is configured as described above, it has the following excellent effects.

According to the first aspect of the present invention, it is possible to suppress the vibration of the spindle during high-speed rotation to ensure high rotation accuracy, and to reduce the pressure of the cylinder for clamping the tool holder on the spindle. Even if it reaches zero,
Since the tool holder does not come off from the spindle, it is possible to prevent the tool holder from coming off and causing a serious accident.

According to the second aspect of the invention, the structure for supplying the pressure fluid to the cylinder and the hydrostatic bearing can be simplified.

[Brief description of drawings]

FIG. 1 is a partial sectional view taken along the line AA of FIG. 3, showing an embodiment of a spindle device embodying the present invention.

FIG. 2 is a vertical cross-sectional view showing the entire spindle device.

FIG. 3 is a partial sectional view showing a part of the spindle device in an enlarged manner.

FIG. 4 is a partial cross-sectional view taken along the line BB of FIG.

FIG. 5 is a perspective view showing exploded main components such as a cylinder and a piston.

[Explanation of symbols]

1 ... Spindle head, 2 ... Spindle, 4 ... Holding hole, 5 ... Tool holder, 6 ... Drive motor, 10 ... Motor shaft, 11 ... Static pressure coupling, 12 ... Clamp rod, 13 ... Clamp mechanism, 16 ... Clamp Cylinder, 17 ... Clamping piston, 20 ... Fluid supply path, 21 ... Branch supply path, 24 ... Vertical groove, 25 ... Horizontal groove, 26 ... Locking body, 27 ... Stop screw,
28 ... concave part, 29 ... convex part, 31 ... hydrostatic bearing, 32 ... branch supply path.

Claims (2)

[Claims] 1. A spindle head is rotatably supported by a spindle head, a motor shaft of a drive motor is connected to a base end of the spindle, and a tool holder is detachably mounted in a holding hole at the tip of the spindle. In a main spindle device in which a clamp rod for clamping and unclamping a tool holder is inserted so as to be able to move forward and backward, a cylinder is provided at the base end of the main spindle and is housed in the cylinder at the base end of the clamp rod. Is provided, and an unclamping prevention mechanism is provided between the cylinder and the piston to prevent the clamp rod from moving in the unclamping direction when the spindle rotates, and the spindle and the motor shaft are connected via a pressure fluid. A spindle device characterized by being coupled via a hydrostatic coupling for transmitting a rotational force. 2. The spindle device according to claim 1, wherein a fluid supply passage for branching and supplying a pressure fluid to the cylinder and the static pressure coupling is provided in the spindle head.