JP2008105110A - Tool clamping mechanism of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new tool clamping mechanism preventing a clamped tool from coming off by a simple configuration. <P>SOLUTION: When a draw bar 3 moves upward and clamps a tool or a pull-stud of a tool holder by its front end, a claw-like member 25 provided in the inside of a guide ring 7 connected with the draw bar 3 is engaged with a groove 26 provided at the outer periphery of a main shaft (as shown Fig.2(a)) so that travel of the draw bar is prevented and the tool or the tool holder does not come off the main shaft. Then, a roller 9 descends to press a ring-like member 28 and separate the claw-like member 25 from the groove 26. The roller 9 descends furthermore and presses the guide ring 7 and the draw bar 3 down to unclamp the tool or the tool holder (as shown Fig.2(b)) so that travel of the draw bar 3 is securely locked to prevent the tool or the tool holder from coming off by the simple configuration. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spindle structure of a machine tool, and relates to a tool clamping mechanism for attaching a tool to the spindle.

  A machine tool mounts a tool or a tool holder in a replaceable manner at the tip of a spindle and performs various types of processing. The spindle structure for attaching the tool or the tool holder to the spindle is such that the draw bar is moved along the axis of the spindle relative to the spindle and the tool or tool holder pull stud is held by the ball chuck or collet, and the tool is moved into the spindle. By pulling in, the spindle taper surface and tool shank taper surface are brought into close contact with each other to clamp the tool. In addition, the draw bar is moved in the reverse direction to release the pull stud from the ball chuck or collet and release the tool or tool holder.

  In recent years, with the improvement in productivity of machine tools, a spindle having a higher cutting ability is required in order to obtain a powerful and high-quality cutting ability. For this reason, there is a case where the pulling force due to the cutting load exceeds the pulling force of the spring that clamps the tool, and it is required to increase the tool holding force of the spindle. Various improvements to the spindle structure have been proposed to ensure tool retention by the spindle.

For example, a mechanism for amplifying a pulling force transmitted to the ball chuck portion by amplifying a force along the axial direction of the draw bar between the draw bar and the ball chuck portion to increase a tool holding force. A method is known (see Patent Document 1).
In addition, three stoppers and pieces are arranged between the step provided on the inner peripheral surface of the main shaft into which the draw bar is inserted and the nut fixed to the rear end of the draw bar, and a collar is provided between the step and the collar. With this spring, the collar is urged in the nut direction at the rear end of the draw bar, and the cylinder rod is moved backward, so that the collar is moved backward by the spring and the piece engaged with the tapered surface of the collar is moved. There is also known an invention in which the draw bar is prevented from moving forward (the direction in which the tool is pulled out) by moving the draw bar in the center direction and being disposed between the stoppers, thereby ensuring tool holding (see Patent Document 2). ).

  Further, the pressure receiving body provided at the rear end of the draw bar is urged rearward by a disc spring to urge the draw bar rearward, and the tool is drawn into the main shaft and held at the tip of the draw bar. A through hole with a partial taper is provided, a lock rod is inserted into the hole with a tapered portion of the position, a spring is arranged between the lock rod and the rear end surface of the draw bar, and the rear end of the lock rod's tip pressure receiving body. A radial hole is provided in the taper portion of the through hole of the pressure receiving body in the radial direction, and a sphere is inserted into the radial hole. When the draw bar is retracted and the tool is held, the sphere is When the sphere is pressed outward by the taper part of the lock rod and the sphere engages with the recess provided in the main shaft to prevent the drawbar from moving, First The lock rod is pressed and the sphere is moved in the center direction by the small diameter portion of the taper portion of the lock rod to unlock the main shaft, the pressure receiving body and the draw bar by the sphere, and then the pressure receiving body is pressed to move the draw bar forward. There is also known an invention that pushes out and releases the clamp of the tool (see Patent Document 3).

  Furthermore, a through hole extending in the radial direction is provided in a nut provided at the rear end of the draw bar, a lock pin biased by a spring is provided in the through hole, and the draw bar is pulled rearward by a disc spring, and the tool When the clamp pin protrudes from the outer periphery of the nut and engages with the end of the main shaft to prevent the nut and drawbar from moving forward, ensuring tool retention, and unclamping the tool , By advancing a pressing rod having a tapered surface that engages with a tapered surface provided on the lock pin, the lock pin is retracted into the nut, and the nut and draw bar are moved forward in the main shaft to hold the tool. An invention to be solved is also known (see Patent Document 4).

JP 2000-296404 A JP 2001-150211 A JP-A-8-1415 Japanese Patent Laid-Open No. 10-138019

  When the tool is clamped and held by the pulling force of the spring, the tool may be pulled out by the pulling force due to the cutting load. This problem remains even if the pulling force amplification mechanism described in Patent Document 1 is used. The inventions described in Patent Documents 2 to 4 that lock the movement of the draw bar after clamping the tool have a complicated structure.

  Accordingly, an object of the present invention is to provide a new structure capable of preventing a clamped tool from falling off with a simple mechanism.

  According to the present invention, a tool or a tool holder is held by a gripping mechanism for gripping a tool at the tip of a spindle or a pull stud of a tool holder by sliding a draw bar in the spindle shaft rearward along the axial direction of the spindle by a repulsive force of a spring. A clamping mechanism of a machine tool that clamps and unclamps a tool or a tool holder by sliding the draw bar forward along the axial direction of the main shaft against the repulsive force of the spring, A guide ring connected to the rear end and surrounding the main shaft, a claw-shaped member provided in the guide ring and biased inward by an elastic member, and provided on the outer periphery of the main shaft. A recess in which the claw-like member engages with the biasing force of the elastic member when the tool or the tool holder is clamped, and the main shaft behind the guide ring When the tool or the tool holder is unclamped, the guide ring is pushed by a member that moves forward, and the claw-like member is released from the recess against the force of the elastic member. The tool or tool holder is prevented from falling off the main shaft by restricting sliding of the draw bar in the direction of unclamping the tool or tool holder.

  The present invention has a simple structure in which a claw-like member, a concave portion that engages with the claw-like member, a member that releases the claw-like member from the concave portion, and the like are simply added to the conventional main shaft structure, and the tool or the tool holder is reliably The tool or the tool holder can be reliably prevented from falling off the main shaft.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows the structure of a ball chuck type tool clamping mechanism according to an embodiment of the present invention. FIG. 2 is an explanatory view of the state of the operation of the rear end of the draw bar in the embodiment, FIG. 2 (a) is a state when the tool or the tool holder is clamped, and FIG. 2 (b) is the tool or the tool holder. The state when unclamping is shown.
A draw bar 3 is disposed in a through hole provided along the axis of the main shaft 1. A ball 4 is disposed at the tip of the draw bar 3 in the circumferential direction, and a ball chuck portion is formed for gripping a pull stud 11 attached to a tool shank 10 of a tool or a tool holder. A draw bar guide 5 is attached to the rear end of the draw bar 3, and a rod 6 that passes through the main shaft 1 in the radial direction and slides in the axial direction is attached to the draw bar guide 5. A guide ring 7 that slides in the axial direction on the outer periphery of 1 is fixed. The draw bar 3, the draw bar guide 5, the rod 6, and the guide ring 7 are fixed to and integrated with each other, and the rod 6 is guided by an oblong hole provided in the main shaft axis direction (not shown). The draw bar guide 5 and the guide ring 7 slide in the axial direction.

  A spring 2 as an elastic member is disposed between the stepped portion 1 a on the inner peripheral surface of the main shaft 1 and the drawbar guide 5 so as to surround the drawbar 3 with the same axis as the drawbar 3, and the drawbar 3 is moved by the repulsive force of the spring 2. The pull stud 11 is drawn into the through hole of the main shaft 1.

  Between the guide ring 7 and the main shaft 1 is disposed a claw-like member 25 that is rotatably supported by a fulcrum 24 fixed to the guide ring 7. On the outer periphery of the main shaft 1, there is provided a recess in which the claw portion of the claw-like component 25 can be embedded. In this embodiment, this recess is formed by a groove 26. The claw-like member 25 is urged by an elastic body 27 in a direction to be buried in the groove 26. Further, an inclined surface that is lowered toward the center of the draw bar 3 is formed at the upper end portion of the claw-shaped member 25, and a member having an inclined surface that engages with the inclined surface is formed in a ring shape. 1 is provided with a link-like member 28 which is inserted into 1.

3 and 4 are schematic views of a tool changer in a machine tool to which a spindle equipped with the tool clamping mechanism of this embodiment is applied. Since this tool changer is already known (see JP 2006-123116 A and JP 2005-28460 A), an outline is shown. FIG. 3 is a side view with the cover and cam member removed, and FIG. 4 is a side view with the cover and cam member attached.
A turret 13 holding a plurality of tools (tool holders) is rotatably supported on a support 12 by a turret fulcrum 14 and is urged counterclockwise in FIG. 3 by a spring (not shown). The main shaft 15 is coupled to the main shaft head 16 and can be moved in the vertical direction by a guide. The spindle head 16 includes a first cam 18 and a second cam 19 for swinging the turret 13.

  When the tool change command is received, the spindle head 16 rises from the position shown in FIG. As the spindle head 16 rises, the swing roller 13a moves along the cam surfaces of the first cam 18 and the second cam 19 provided on the side surface of the spindle head 16, and the turret 13 is moved from the spindle 15 to the tool or A swing operation for pulling out the tool holder is performed, and the grip 21 is inserted into a groove provided in the tool shank 10. Further, when the spindle 15 (spindle head 16) rises, the arm 8 rotatably supported by the arm fulcrum 17 on the top of the spindle head 16 is pushed out to the third cam 20, and rotates counterclockwise in FIG. The roller 9 coupled to the tip of the arm pushes down the guide ring 7 above the main shaft 15. Thereby, the ball chuck portion of the draw bar 3 releases the grip of the tool or the tool holder, and at the same time, the tool or the tool holder held by the grip 21 is pulled out from the spindle shaft 1 as the spindle 15 rises. The main shaft 15 rises to a position where the turret gear 22 provided on the outer peripheral portion of the turret 13 and the main shaft gear 23 provided at the lower end of the main shaft 15 are engaged with each other, and the turret 13 is rotated by the rotation of the main shaft 15 to perform a tool indexing operation. That is, without using a dedicated power source, a series of tool changing operations including a tool clamping / unclamping operation is realized by the vertical movement of the spindle head 16 and the rotation of the spindle.

Next, with reference to FIG. 2, a description will be given of the clamping and locking of the tool and the unlocking and unclamping operation of the tool in the present embodiment.
FIG. 1 and FIG. 2 (a) show a state where the pull stud 11 of the tool or tool holder is gripped by the ball chuck portion. The draw bar guide 5 and the draw bar 3 are pulled rearward (upward in FIGS. 1 and 2) by the repulsive force of the spring 2 disposed between the step portion 1a provided on the main shaft and the draw bar guide 5, and the ball chuck portion The pull stud 11 is clamped by the ball 4. At this time, as shown in FIG. 2A, the claw-like member 25 is buried in the groove 26 provided in the main shaft 1, and the sliding of the guide ring 7 in the direction of releasing the tool or the tool holder is restricted. . As a result, sliding of the draw bar 3 coupled to the guide ring 7 in the direction of releasing the tool or tool holder is restricted, and the draw bar 3 moves even if there is a cutting load exceeding the pulling force by the spring 2. Without holding the state where the pull stud 11 is clamped by the ball chuck portion, the tool or the tool holder is prevented from falling off.

  When the tool is changed, the spindle head 16 is raised, the roller 9 coupled to the arm 8 is advanced, and the ring-shaped member 28 is pushed downward as shown in FIG. The surface is inserted into the inclined surface of the claw-like member 25 to push the claw-like member 25 in the direction of the outer diameter of the draw bar 3 against the force of the elastic body 27. The claw portion of the claw-like member 25 that has been spread out is disengaged from the groove of the main shaft 1 so that the draw bar 3 (guide ring 7, rod 6, draw bar guide 5) can be moved relative to the main shaft 1. The claw-like member 25 is expanded and contacts the inner peripheral surface of the guide ring 7 (see FIG. 2B). Further, when the roller 9 advances, the guide ring 7 is pushed down through the ring-shaped member 28 in FIG. As a result, the draw bar 3 is pushed down to the position where the tool is released with respect to the main shaft 1 through the rod 6 and the draw bar guide 5, and the diameter of the through hole provided in the main shaft 1 is increased to the tip of the draw bar 3. The chuck portion is opened by the balls 4 arranged in the circumferential direction, and the ball chuck portion performs a tool releasing operation. At this time, as described above, the turret 13 swings and the grip 21 is inserted into the groove provided in the tool shank 10. Further, the spindle head 16 rises and the tool or tool holder held by the grip 21 is pulled out from the spindle shaft 1. Then, the turret gear 22 provided on the turret 13 and the main shaft gear 23 provided on the main shaft 15 mesh with each other, the turret 13 is rotated by the rotation of the main shaft 15 and the tool indexing operation is performed. 16 is lowered, the pull stud 11 of the tool is inserted from the tip of the main shaft, and the roller 9 is relatively retracted, whereby the draw bar 3 (guide ring 7, rod 6, draw bar guide 5) is shown by the repulsive force of the spring 2. 1 and 2, the pull stud 11 is moved upward, and the ball chuck portion holds the pull stud 11 by the reduced diameter portion in the main shaft 1. Then, the claw-like member 25 is urged by the elastic body 27 to be fitted and buried in the groove 26 of the main shaft 1, and the draw bar 3 (guide ring 7, rod 6, draw bar guide 5) moves relative to the main shaft 1. Prevent and lock. Thereby, the tool is reliably held by the draw bar 3.

  In the above-described embodiment, the pull stud 11 of the tool or the tool holder is gripped and clamped by the ball chuck portion that uses a ball, but the tool or the pro stud of the tool holder is gripped using a collet, and the tool is It may be retracted into the main shaft.

It is explanatory drawing explaining the structure of the ball chuck type tool clamp mechanism which is one Embodiment of this invention. It is a state explanatory view of the operation of the drawbar rear end in the embodiment. It is a schematic diagram of the tool change apparatus in the machine tool which applies a main axis | shaft provided with the tool clamp mechanism of the embodiment, and is the side view which removed the cover and the cam member. It is a schematic diagram of the tool change apparatus in the machine tool which applies a main axis | shaft provided with the tool clamp mechanism of the embodiment, and is the side view which attached the cover and the cam member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main shaft shaft 2 Spring 3 Draw bar 4 Ball 5 Draw bar guide 6 Rod 7 Guide ring 8 Arm 9 Roller 10 Tool shank 11 Pull stud 12 Support 13 Turret 14 Turret fulcrum 15 Main shaft 16 Main shaft head 25 Claw-shaped member 26 Groove 27 Elastic body 28 Ring Shaped member

Claims (1)

The draw bar in the spindle shaft is slid rearward along the axial direction of the spindle by the repulsive force of the spring, and the tool or the tool holder is clamped by the gripping mechanism that grips the tool at the tip of the spindle or the pull stud of the tool holder, In a clamping mechanism of a machine tool that unclamps a tool or a tool holder by sliding the draw bar forward along the axial direction of the main shaft against the repulsive force of a spring,
A guide ring connected to the rear end of the draw bar and surrounding the spindle shaft;
A claw-like member provided inside the guide ring and biased inward by an elastic member;
A recess provided on the outer periphery of the main shaft, and engaged with the claw-like member by the biasing force of the elastic member when the tool or the tool holder is clamped;
It is arranged behind the guide ring so as to surround the spindle shaft, and when the tool or the tool holder is unclamped, it is pushed by a member that moves the guide ring forward and resists the force of the elastic member. And a member that is released from the recess,
A tool clamping mechanism of a machine tool, characterized by restricting sliding of the draw bar in a direction to unclamp the tool or tool holder.

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