JP2006062042A - Spindle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a technical issue of vibration caused from a disc spring at high-speed rotation. <P>SOLUTION: In this spindle device 1, a draw bar 5 is drawn and moved backward by a tool clamp mechanism 6 provided on a spindle 3 to clamp a tool holder T in the spindle 3 through a clamp member engaged with the tip of a clamp rod, and the draw bar 5 is pushed out and moved forward by a tool clamp mechanism 8 provided on a spindle head 2 to unclamp the tool holder T from the spindle 8. The tool clamp mechanism 6 is so constructed that a pressure fluid is supplied to a cylinder chamber 9a formed by a cylinder 9 provided in the spindle 3 and a piston 5a, whereby the draw bar 5 is pulled and moved backward by the fluid pressure to hold the tool clamp state, and a spring member 10 for applying energizing force to hold the tool clamp state even if the fluid pressure in the cylinder chamber 9a drops to the piston 5a of the draw bar 5 is provided in the cylinder chamber 9a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a spindle device in a machine tool.

FIG. 3 is a sectional view of a spindle device of a conventional machine tool. FIG. 3 shows, for example, a spindle device 90 of a machining center that is one of machine tools, and has a tool mounting hole 68 in which a tool holder T can be attached and detached at the tip of a main shaft 61, and a tool inserted into the tool mounting hole 68. A draw bar 65 for clamping and unclamping the holder T with respect to the main shaft 61 is inserted into the main shaft 61 so as to be movable forward and backward. At the time of tool clamping, the draw bar 65 is pulled and retracted by the tool clamping mechanism 62 using the elastic force of the disc spring 96 provided on the spindle 61, and the tool holder T is moved through the collet 64 engaged with the tip of the draw bar 65. Clamp to 61. When the tool is unclamped, the draw bar 65 is pushed out by the action of the unclamp cylinder 92 and advanced to unclamp the tool holder T from the main shaft 61. A large number of disc springs 96 are used in the spindle 61 in the tool clamp mechanism 62 of the conventional spindle device 90. The disc spring 96 urges the draw bar 65 backward to strongly clamp (fix) the tool holder T to the main shaft 61 (see, for example, Patent Document 1).
JP 2002-80099 (paragraph numbers 0072 to 0073, FIG. 8)

  However, in such a machining center, for example, when the spindle is rotated at a high speed to perform precision machining, an unbalance occurs due to the behavior of the disc spring, and this has become a neck technology that causes vibration and interferes with precision machining. .

  Therefore, the present invention was devised to solve these problems, and eliminates the neck technology in which a disc spring was a vibration source in high-speed rotation of a headstock of a machining center that performs precision machining. This is the issue.

According to the first aspect of the present invention, the spindle head is rotatably supported by the spindle head, and has a tool mounting hole in which the tool holder can be attached and detached at the tip of the spindle, and the tool holder inserted into the tool mounting hole is attached to the spindle. A draw bar for clamping and unclamping is inserted into the main shaft so as to be able to move forward and backward, and the draw bar is pulled and retracted by a tool clamp mechanism provided on the main shaft, and the tool holder is moved to the main shaft through a clamp member that engages the tip of the draw bar. In the spindle device that clamps and unclamps the tool holder from the spindle by pushing and advancing the draw bar by a tool unclamping mechanism provided on the spindle head.
The tool clamping mechanism supplies a pressure fluid to a cylinder chamber formed by a cylinder provided in the main shaft and a piston provided integrally with the draw bar, and the draw bar is pulled and retracted by the fluid pressure, so that the tool clamp state is maintained. A spring member is provided in the cylinder chamber for applying an urging force to the piston of the draw bar so that the tool clamp state can be maintained even if the fluid pressure in the cylinder chamber decreases.
According to a second aspect of the present invention, the spring member is a coil spring inserted through a draw bar.

According to the first aspect of the present invention, the conventional disc spring is abolished and a tool clamping mechanism using the fluid pressure of the cylinder is adopted, and the disc spring is provided in the cylinder chamber in case the fluid pressure drops due to a power failure or the like. By installing a weaker spring member, the unbalance due to the behavior of the conventional disc spring can be eliminated, and the tool clamp state can be reliably maintained with a simple configuration that only houses the spring member in the cylinder chamber, and the tool comes off. I am trying not to.
According to the invention which concerns on Claim 2, a tool clamp state can be reliably hold | maintained using a simple spring.

  According to the first and second aspects of the present invention, the conventional disc spring is abolished and a tool clamping mechanism using a clamping cylinder and a simple spring member is used, so that the disc spring serves as a vibration source. It is possible to eliminate the imbalance due to the behavior of the disc spring during high-speed rotation, and to securely hold the tool clamp state with a simple configuration.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a spindle device of a machining center which is a machine tool of the present invention. As shown in FIG. 1, a spindle 3 is rotatably supported by a spindle head 2 of the spindle device 1, and a tool mounting hole 4 is provided at the tip of the spindle 3 to which a tool holder T can be attached and detached. A draw bar 5 for clamping and unclamping the inserted tool holder T with respect to the main shaft 3 is inserted into the main shaft 3 so as to be able to advance and retreat, and the draw bar 5 is pulled and retracted by a tool clamp mechanism 6 provided on the main shaft 3. The tool holder T is clamped to the main shaft 3 via a collet 7 as a clamping member that engages with the tip of the draw bar 5, and the draw bar 5 is pushed forward by the tool unclamp mechanism 8 provided on the main shaft head 2 to advance the tool holder T. Is unclamped from the main shaft 3.

  As shown in FIG. 1, the tool clamping mechanism 6 supplies pressure fluid by a pump to a cylinder chamber 9a formed by a cylinder 9 provided in the main shaft 3 and a piston 5a provided integrally with the draw bar 5. The draw bar 5 is retracted (pulled to the left) by the fluid pressure, and the tool clamp state is maintained. In the cylinder chamber 9a, a coil spring 10 is provided as a spring member that applies an urging force that can maintain the tool clamped state to the piston 5a of the draw bar 5 even if the fluid pressure in the cylinder chamber 9a decreases. Inside the draw bar 5, a fluid supply path 5 b that communicates from the rear end of the draw bar 5 to the cylinder chamber 9 a is formed.

  In operation, when a pressure fluid is supplied from the hydraulic device (not shown) to the cylinder chamber 9a via the supply path 5b, the draw bar 5 is pulled backward (leftward in the figure) by this fluid pressure and moves backward. As a result, the stepped portion on the inner surface of the collet 7 engaged with the concave portion 5c at the tip end of the draw bar 5 rides on the convex portion 5d at the tip end of the draw bar 5, and the collet 7 is forcibly opened by this stepping, and the tool holder T is depressed. The convex part of the outer peripheral surface of the collet 7 abuts, and the tool holder T is clamped to the main shaft 3.

In the present embodiment, a two-face restraint type holder (for example, HSK) is used for the tool holder T, the rigidity of the connection between the tool holder T and the main shaft 3 is increased, and the repeatability at the time of clamping / unclamping is improved. Furthermore, the tip of the main shaft 3 expands due to centrifugal force during high-speed rotation, and the shank portion of the tool holder T bites and prevents it from becoming detached.
In this state, the spindle is rotated by a spindle motor (not shown), and machining is performed with the tool of the tool holder T at the tip.

  The tool unclamping mechanism 8 is composed of an unclamping cylinder 11 disposed on the spindle head 2. A draw bar extruding portion 12a is formed on the piston member 12 in the unclamping cylinder 11, and a flange member 13 protruding from the opening of the main shaft 3 is fixed to the rear end of the piston 5a of the draw bar 5 in opposition thereto.

  When the machining is completed and the tool holder T is unclamped for tool replacement, as shown in FIG. 2, the pressure fluid is supplied to the rear cylinder chamber 11 a of the unclamping cylinder 11, and the draw bar pushing portion of the piston member 12. 12a pushes the flange member 13 of the draw bar 5 and moves the draw bar 5 forward. At this time, the supply of pressure fluid to the cylinder chamber 9a in the main shaft 3 is stopped, and the fluid in the cylinder chamber 9a is pushed out by the piston 9a and extracted through the pressure fluid supply passage 5b. Then, the convex portion 5d at the tip of the draw bar 5 passes through the collet 7, and the inner surface of the collet 7 engages with the concave portion 5c at the tip of the draw bar 5 to be contracted and restored to the axial center side. As a result, the tightening of the tool holder T with respect to the tool mounting hole 4 is released, and the tool holder T is unclamped. The tool holder T can be extracted from the spindle 3 by a tool gripping means (not shown).

  A coil spring 10 is provided in the cylinder chamber 9a in the main shaft 3 so as to be concentrically inserted into the draw bar 5 with the piston 5a. The coil spring 10 urges the piston 5a of the draw bar 5 with a clamping force enough to hold the draw bar 5 at the clamp position even if the hydraulic pressure in the cylinder chamber 9a is reduced due to a power failure or the like from the tool clamp state of FIG. It has become. Since the clamping force of the tool holder T is normally generated by the fluid pressure in the cylinder chamber 9a, the clamping force by the coil spring 10 does not require a large elastic force like a conventional disc spring. Even if the mass of this coil spring 10 and the conventional disc spring is compared, it is about 1/20, and there is almost no influence of the vibration by the behavior of the coil spring 10, and the balance problem can be kept small.

The present invention can be variously modified and changed within the scope of the technical idea.
The pressure fluid is not limited to oil pressure, and may be water pressure or air pressure.
The structure of the clamp part may be replaced with another form such as a pull stud type.
The spring member is not limited to a coil spring but may be a leaf spring or the like. Any spring force may be used as long as the clamp holding force is applied when the pressure in the cylinder chamber drops.

It is sectional drawing of the spindle apparatus of this invention, and a tool clamp state is shown. The tool unclamped state of the spindle device shown in FIG. 1 is shown. It is sectional drawing of the conventional main axis | shaft apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spindle device 2 Spindle head 3 Spindle 4 Tool mounting hole 5 Draw bar 5a Piston 5b Supply path 6 Tool clamp mechanism 7 Collet as clamp member 8 Tool unclamp mechanism 9 Cylinder 9a Cylinder chamber 10 Coil spring (spring member)
T Tool holder

Claims (2)

A draw bar for supporting the spindle rotatably on the spindle head and having a tool mounting hole in which the tool holder can be attached and detached at the tip of the spindle, and clamping and unclamping the tool holder inserted into the tool mounting hole with respect to the spindle Is inserted into the main shaft so as to be able to move forward and backward, and the draw bar is pulled and retracted by a tool clamp mechanism provided on the main shaft, and the tool holder is clamped to the main shaft via a clamp member engaged with the tip of the clamp rod, In the spindle apparatus in which the draw bar is pushed forward by the provided tool unclamping mechanism and the tool holder is unclamped from the spindle,
The tool clamping mechanism supplies a pressure fluid to a cylinder chamber formed by a cylinder provided in the main shaft and a piston provided integrally with the draw bar, and the draw bar is pulled and retracted by the fluid pressure, so that the tool clamp state is maintained. Hold and
A main shaft device characterized in that a spring member is provided in the cylinder chamber for applying an urging force that can maintain the tool clamped state to the piston of the draw bar even if the fluid pressure in the cylinder chamber decreases.   The spindle device according to claim 1, wherein the spring member is a coil spring inserted through a draw bar.

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