JPH03117530A - Tool clamp mechanism of automatic tool replacing device - Google Patents

Abstract

PURPOSE:To enable a tool replacement even during the rotation of a main shaft and to shorten the replacing time, by energizing the cylindrical clamp piston outer-fitted slidably to a collet by a spring to the clamp side and operating it to the unclamp side by a hydraulic cylinder. CONSTITUTION:When a pressure oil is fed to a cylinder 25 for unclamping through a pressure oil feeding pass 30 and a piston 27 for unclamping is moved to the left part against a spring 29, the piston 27 makes a clamp piston 22 to contract a conical spring 23 with its pushing to unclamping side via a thrust bearing 28 and a tool T is unclamped with a collet 21 being opened. Simultaneously a tool connecting fitting 44 to which a wire 45 is retracted is fitted to a tool holding part 35 with the retreat of a work lever 37, the tool T is stored and held, the succeeding tool T1 is extruded, a flange part 47 is stopped at the position where the collet 21 is abutted on the abuttment position 21a and the tool is replaced. When the pressure oil of the hydraulic cylinder 25 is eliminated, a clamp piston 22 and the piston 27 for unclamping are returned to a clamping state with the actions of the conical spring 23 and coil spring 29, the collet 21 is closed and a tool T1 is clamped.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tool clamping mechanism of an automatic tool changer in an NC machine tool such as a machining center.

BACKGROUND OF THE INVENTION Conventional automatic tool changers in NC machine tools exchange tools between a tool magazine that stores a large number of tools (installed in a tool holder) and the main shaft of a knee machine tool. ing. When exchanging tools, the next tool transferred from the tool pot of the tool magazine to the tool exchange arm is held in the exchange head, and the exchange head moves to the spindle side positioned at the tool exchange position, where the tool is transferred to the tool exchange arm. The most common structure is one in which the previous tool is exchanged by moving the exchange arm back and forth and rotating.

However, the above-mentioned conventional automatic tool changer requires a tool changer arm, its auxiliary equipment, and a relatively large space to install them, and has the problem of being large, complicated, and expensive.

In addition, with conventional devices, it takes time and effort to position and align the spindle and tool exchange arm to the exchange position, which limits the shortening of tool exchange time, and requires repeated positioning at high speed. The problem was a decrease in positioning accuracy.

Furthermore, in the case of small-diameter tools with short machining times, the proportion of tool change time, which is non-machining time, increases significantly, which is a major obstacle to increasing work efficiency.

On the other hand, in view of the problems of the conventional device described above, the present inventors
A plurality of tools are accommodated in the hollow hole of the spindle consisting of a hollow shaft so as to be movable in the axial direction, and these tools are replaced with a chuck that clamps the tools provided at the front end opening of the spindle, thereby eliminating wasted tool exchange. We first proposed an automatic tool changer that could eliminate as much movement as possible, reduce non-machining time to a large extent, and be simple and inexpensive to manufacture.
3-93867 and Japanese Patent Application No. 63-228092).

Problems to be Solved by the Invention However, the tool clamp mechanism shown in the automatic tool changer related to the above patent application is one that opens and closes the collet in conjunction with the rotational movement of the main shaft after it has stopped once. , it was not possible to change the tool while the spindle was rotating.

The present invention was made to solve these problems, and in the above-mentioned automatic tool changer, the collet can be opened and closed to change the tool regardless of whether the main shaft is rotating or stopped. It is an object of the present invention to provide a tool clamp mechanism that can further reduce tool exchange time.

Means for Solving the Problems In order to achieve the above object, in the present invention, the chuck for clamping the tool includes a collet fixed to the front opening of the main shaft, and a collet slidably fitted onto the collet. The clamp piston comprises a cylindrical clamp piston, a spring means for biasing the clamp piston toward the clamp side, and an unclamping hydraulic cylinder that operates the clamp piston toward the unclamp side against the spring means. It is characterized by the presence of

The unclamping hydraulic cylinder can be provided on the fixed part, that is, the spindle head, or on the rotating part, that is, the spindle head.

Operation With the above configuration, the collet opens and the tool can be replaced by simply supplying pressure oil to the unclamping hydraulic cylinder, not only when the main shaft is stopped but also when it is rotating.

Example Embodiments of the present invention will be described below based on the drawings.

The drawing shows an automatic tool changer with a tool clamping mechanism according to the invention.

10 is a main shaft head, and 11 is a main shaft, which is formed by a hollow shaft having a hollow hole 12 penetrating over the entire length. The main shaft 11 is rotatably supported by the main spindle head 10 via bearings 13 and 14, and a rotor 16 of a spindle motor 15 built into the main spindle head 10 is externally fitted and fixed, and is integrated with the spindle motor 15. has been done. spindle motor 1
The stator 17 of No. 5 is fixed to the spindle head 10.

A tool T is provided in the front end opening 11a of the main shaft 11 as described later.
A chuck 20 for clamping is provided. A tapered guide portion 18 is formed inside the front end opening 11a to guide the tool T accommodated in the hollow hole 12 to the chuck 20.

The chuck 20 includes a collet 21 fitted into the front end opening 11a, a cylindrical clamp piston 22 fitted around the collet 21 in a slidable manner, and a clamp piston 22 fitted around the outer periphery of the collet 21. The collet 21 is provided with a disc spring 23 that biases toward the clamp side (rightward in the drawing), and the collet 21 is always closed by the clamp piston 22. Further, the clamp piston 22 is able to slide smoothly in the axial direction by a stroke bearing 24 interposed between the outer circumferential surface of the clamp piston 22 and the inner circumferential surface of the front end opening 11a.

Reference numeral 25 denotes an unclamping hydraulic cylinder, which is fixed to the main shaft front cover 26 with bolts.

Reference numeral 27 denotes an unclamping piston, which is formed into a cylindrical body that fits into the front end opening 11a of the main shaft 1, and has a front wall 27a.
A thrust bearing 28 is interposed between the clamp piston 22 and the front end surface of the clamp piston 22. The unclamping piston 27 is fitted into the cylinder 25 so as to be slidable in the axial direction, and is biased toward the front side of the main shaft 1 (toward the right in the drawing) by a coil spring 29 built into the cylinder 25. The cylinder 25 is pushed toward the unclamping side (leftward in the drawing) against the coil spring 29 by pressure oil supplied through a pressure oil supply path 30 provided in the cylinder 25.

Reference numeral 31 denotes a tool holder that accommodates and holds a plurality of tools T, and constitutes the main body of an automatic tool changer that exchanges the tools T by reciprocating the housed tools T individually in the axial direction and replacing them with the chuck 20. There is. The tool holder 31 is removably inserted into the hollow hole 12 of the spindle 11 with a slight gap, and the flange portion 31a connected to the rear end is fixed to the rear cover 32 of the spindle head 10 with bolts 33. and is fixedly supported.

The tool holder 31 has a plurality of guide holes 3 extending parallel to the axis.
A tool holding portion 35 is formed at the front end opening portion of each guide hole 34, and a locking step portion 36 for a pullback spring 39, which will be described later, is provided at the intermediate portion.

Reference numeral 37 denotes an operating rod that is slidably inserted into each guide hole 34, and a collar portion 38 and a locking step portion 36 of the guide hole 34 are connected to each other at the rear end.
It is urged toward the rear standby position by a pullback spring 39 interposed between the two.

40 is a cylinder device for extruding tools, which is fixed to the rear cover 32. The cylinder device 40 has a plurality of actuating rods 3
7, and when each air cylinder 41 is operated, its piston rod 42
The pressing piece 43 attached to the tip of the actuating rod 37 collides with the flange 38 of the actuating rod 37, and moves the actuating rod 37 into the guide hole 3 against the pullback spring 39.
4 toward the tool holding portion 35 side.

Reference numeral 44 denotes a tool connecting fitting, which is connected to the front end of each operating rod 37 via a flexible connecting wire 45.
A tool T is rotatably held via a bearing 46 . The connecting wire 45 is a known wire used as a transmission means in various mechanical devices.

When the operating rod 37 is in the retracted position, the connecting wire 45 is drawn into the guide hole 34, the tool connecting fitting 44 is fitted into the tool holding part 35, and the tool T is housed and held in a predetermined position. Ru. On the other hand, when the operating rod 37 is in the forward position, the tool T is pushed out individually via the connecting wire 45, and the tool T is guided by the guide portion 18 and inserted into the collet 21 in the unclamped state. The tool T stops at a fixed position where the positioning flange 47 provided at the base end of the tool T abuts against the abutting part 21a of the collet 21, protruding from the front end of the collet 21 by a predetermined length. In this state, the collet 21 closes and clamps the tool T.

FIG. 1 shows a state in which the tool T is clamped, and when the main shaft 11 rotates, the tool T clamped by the collet 21 rotates together with the main shaft 11, and cutting is performed.

Next, in order to open the collet 21 and replace the tool T, as shown in FIG. The unclamping piston 27 pushes the clamp piston 22 toward the unclamping side (leftward in the drawing) through the thrust bearing 28 and compresses the disc spring 23. This movement of the clamp piston 22 opens the collet 21 and unclamps the tool T. At the same time, the tool extrusion cylinder device 40 of the automatic tool changer opens the collet 21 and unclamps the tool T.
operates as described above, and after pulling the unclamped tool T into the retracted position, the next tool T is pushed out and inserted into the collet 21, and the tool is replaced.

Thereafter, when the pressure oil supplied to the unclamping hydraulic cylinder 25 is removed, the clamp piston 22 and the unclamping piston 27 return to the clamped state shown in FIG. 1 by the action of the disc spring 23 and the coil spring 29. The collet 21 closes and the replaced tool T is scrubbed.

The tool exchange operation described above is not related to the rotational movement of the main spindle 11, so it can be performed at any time not only when the main spindle 11 is stopped, but also while the main spindle 11 is rotating.

FIG. 3 shows another embodiment.

In the previous embodiment, the unclamping hydraulic cylinder 2
In this embodiment, the unclamping hydraulic cylinder 25 is attached to the main shaft 11.
The clamp piston 22 is built into the front end opening 11a of the main shaft 11, and the clamp piston 22 is directly actuated by the pressure oil supplied through the pressure oil supply path 50 provided in the main shaft 11, so the structure is very simple. Note that pressure oil is supplied to the pressure oil supply path 50 via a rotary hydraulic joint 51 attached to the rear side of the spindle head 10.

Furthermore, in this embodiment, the piston rod 42 of the tool extrusion cylinder device 40 and the operating rod 37 are integrated into one rod 52, which has the advantage of simplifying the structure and shortening the overall length. be.

Therefore, in this embodiment as well, the tool can be replaced regardless of whether the main spindle 11 is stopped or rotated, similar to the apparatus of the previous embodiment.

As described in detail, according to the tool clamping mechanism of the present invention, a tool exchange operation is performed in which a plurality of tools housed in the hollow hole of the main spindle are replaced by replacing them with a chuck provided at the front end opening of the main spindle. However, since this can be done at any time not only while the main spindle is stopped, but also while the main spindle is rotating, it is possible to significantly shorten the tool exchange time and, in turn, reduce the machining time.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view of an automatic tool changing bag and stand equipped with a tool clamping mechanism according to the present invention, Fig. 2 is an enlarged longitudinal sectional view of the same essential parts showing an unclamped state, and Fig. 3 is another embodiment. FIG. 10 Spindle head 11... Main shaft 12... Hollow hole 11a... Front end opening 20... Chuck 21... Collet 22... Clamp piston 23... Belleville spring 25... For unclamping Piston 27... Unclamping piston 28... Thrust bearing 29... Coil spring 31... Tool holder 3
4... Guide hole 35... Tool holding part 37
...3 operating rods...return spring 40.
... Cylinder device for pushing out tools 41 ... Air cylinder 42 ... Piston rod Fig. 0

Claims (3)

[Claims] (1) The main shaft is formed as a hollow shaft, and a chuck for clamping tools is provided at the front end opening of the hollow hole of the main shaft, and a plurality of tools are accommodated in the hollow hole so as to be individually movable in the axial direction. Further, in the automatic tool changer, a tool moving means for individually reciprocating the tools in the axial direction is provided at a rear part of the main spindle, and the tool is replaced by the chuck by the tool moving means. a collet fixed to the front opening of the main shaft, a cylindrical clamp piston slidably fitted onto the collet, a spring means for biasing the clamp piston toward the clamp, and the clamp. A tool clamping mechanism for an automatic tool changer, comprising an unclamping hydraulic cylinder that operates a piston toward the unclamping side against the spring means. (2) The tool clamping mechanism for an automatic tool changer according to claim (1), wherein the unclamping hydraulic cylinder is provided at a fixed portion, that is, a spindle head. (3) Claim (1), wherein the unclamping hydraulic cylinder is provided on a rotating part, that is, the main shaft, and pressure oil is supplied through a rotary hydraulic joint attached to the rear side of the main shaft. Tool clamping mechanism of the automatic tool changer described.