JPH0230204Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is characterized in that a cutting tool, such as an end mill, which is attached to the drive rotating spindle of a machine tool via a tool holder, slips out of the tool holder during cutting. This invention relates to a cutting tool coming-out detection device that can be used to detect.

(Conventional technology and its problems) Rotary cutting tools such as end mills are firmly attached to a tool holder that is fitted onto the rotating spindle of the machine tool via an automatic tool changer (ATC), etc., using a chuck mechanism such as a collet chuck. However, during use, ie, during cutting, the tool holder is subjected to a strong force in the direction of pulling out of the tool holder. This acting force in the withdrawal direction often overcomes the tool gripping force of the chuck mechanism and moves the cutting tool in the withdrawal direction with respect to the tool holder.

Conventionally, this is a practical method that can be used to quickly detect when a cutting tool comes out of the tool holder and take appropriate measures, such as automatically interrupting the rotation and feeding of the drive rotating spindle. Since no conventional cutting tool removal detection device had been considered, even if the tool was noticed before the tool fell out of the tool holder, it could lead to fatal defects such as an abnormally deep cutting depth on the workpiece. was.

(Means for Solving the Problems) The present invention provides a cutting tool coming-out detection device that can solve the conventional problems as described above. A tool holder is provided with a chuck portion and a fitting portion on the inner end side of the drive rotating spindle, and an electric contact that abuts the inner end surface of the cutting tool held by the chuck portion; An electrically insulating part is provided for electrically conducting the fitting part through only the electrical contact, and an electrically insulating part of the tool holder is provided between the driving spindle and the workpiece to be cut by the cutting tool. The present invention is characterized in that it includes a power source for causing current to flow through the contact and the cutting tool, and a detection means for detecting a state in which current no longer flows through the current path.

(Example) An example of the present invention will be described below based on the attached illustrative drawings.

Reference numeral 1 denotes a tool holder, which has a chuck portion 2 for holding a cutting tool on the outer end side, and a fitting portion (tapered shank portion) 4 for a rotating spindle 3 for driving a machine tool on the inner end side, and an automatic tool holder. A gripping part 5 that is gripped by a manipulator of the exchanger is provided. The chuck portion 2 is of a conventionally known type, and is composed of a collet 7 and a tightening nut 8 that fit into a tapered hole 6 having a large diameter opening at the outer end of the tool holder 1.

The tool holder 1 includes a fitting part 4 and a gripping part 5.
The upper half 9 has a tapered hole 6, and the lower half 10 has a tapered hole 6. They are connected by a plurality of bolts 14 in the circumferential direction with keys 13 made of electrically insulating material interposed therebetween for torque transmission.

Reference numeral 15 denotes an electrical contact protruding from the upper half 9 into the tapered hole 6 of the lower half 10, which is connected to the inner end surface 16a of a cutting tool held by the chuck 2, such as an end mill 16. come into contact with

Reference numeral 17 is an AC power supply, one of its power supply terminals is connected to a conductor 20 attached to the headstock 19 so as to be in sliding contact with a conductive ring 18 attached to the outer peripheral surface of the driving rotating spindle 3. The other terminal is connected to a work table or the like so as to be electrically connected to the conductive work 21 to be cut by the end mill 16. Reference numeral 22 denotes a detection induction coil, which is held on the headstock 19 in a state where it is loosely fitted to the main spindle 3 at a position closer to the tip of the drive rotating main spindle 3 than the conductive ring 18, and is connected to the control device 23. has been done.

A cutting tool, such as an end mill 16, is previously attached to the tool holder 1 using the chuck portion 2 in a well-known manner before it is set on the drive rotating spindle 3 by a manipulator of an automatic tool changer. At this time, as shown in the figure, the end mill 16 is inserted into the tool holder 1 until the inner end surface 16a of the end mill 16 comes into contact with the electrical contact 15 and is fixed.

The tool holder 1 to which the end mill 16 is attached as described above is taken out from the tool magazine by the manipulator of the automatic tool changer that grips the tool holder 1 via the grip part 5, and is fitted into the drive rotation spindle 3 at the fitting part. Set via 4.
As is well known in the art, by rotating the drive rotary spindle 3 and moving the headstock in a predetermined direction, the work 21 set on the work table can be cut by the end mill 16.

When the end mill 16 is in the state of cutting operation, the high frequency current supplied from the AC power source 17 flows between the drive rotating main shaft 3 and the workpiece 21.
It flows through the upper half 9 of the tool holder 1, the electrical contacts 15 and the end mill 16. Therefore, an induced current is induced in the induction coil 22.

If the end mill 16 overcomes the tool gripping force of the chuck part 2 and is pulled out during cutting,
The inner end surface 16a of the end mill 16 is separated from the electrical contact 15, and high frequency current no longer flows between the drive rotating main shaft 3 and the workpiece 21 via the electrical contact 15. Therefore, no induced current is induced in the induction coil 22. Of course, as long as the headstock 19 and the work table are electrically connected via the machine tool body, a high-frequency current will flow between the drive rotating spindle 3 and the workpiece 21 via the machine tool body. , since the current path at this time is away from the induction coil 22, the induction coil 22 does not react.

As shown above, the end mill 16 is attached to the tool holder 1.
When the robot moves in the direction of leaving the induction coil 22, no induced current is induced in the induction coil 22, so the control device 23 detects a change in the detection signal induced in the induction coil 22, and the induced current is no longer induced in the induction coil 22. The control device 23
For example, a command to stop driving the rotary spindle 3 and a command to stop feeding the headstock can be transmitted from the machine to automatically stop the cutting action.

In the embodiment, the end mill 16 is used as an example of a cutting tool, but any cutting tool that may come off during cutting can be used. Further, one of the power terminals is directly connected to the drive rotating spindle 3 via the conductive ring 18 and the conductor 20, but since the headstock 19 and the drive rotating spindle 3 are electrically conductive, One of the power terminals may be connected to the headstock 19.

When configuring the workpiece 21 to be electrically insulated from the worktable so that the headstock 19 and the workpiece 21 are not electrically connected through the machine tool body, a DC power source is used instead of the AC power source 17. It is also possible to use a power source and detect the position of the end mill 16 based on whether a direct current is flowing through a circuit including the power source, the tool holder 1, and the end mill 16.

(Operations and Effects of the Invention) According to the cutting tool coming out detection device of the present invention which can be implemented and used as in the above embodiment, the cutting tool held in the cutting tool gripping chuck part comes out of the tool holder during cutting operation. When the tool holder moves in the direction, current no longer flows through the electrical contacts of the tool holder and the cutting tool, and this state can be detected by the detection means, so the cutting tool is moved by using the detection signal of the detection means. It is possible to quickly detect the movement of the object.

Therefore, if the cutting tool withdrawal detection signal is used to automatically stop the cutting action as explained in the embodiment, it will be possible to avoid abnormally deep cutting of the workpiece due to the cutting tool withdrawal. It is possible to prevent fatal defects from occurring. Moreover, according to the configuration of the present invention, the structure including the tool holder is simple and can be implemented at relatively low cost.

[Brief explanation of the drawing]

The figure is a longitudinal sectional side view showing an embodiment of the present invention in use. DESCRIPTION OF SYMBOLS 1... Tool holder, 2... Cutting tool gripping chuck part, 3... Rotating main shaft for driving, 4... Fitting part, 5... Gripping part, 9... Upper half of tool holder,
10... lower half of tool holder, 11, 12... electrical insulating material, 13... key made of electrical insulating material, 15...
Electrical contact, 16... End mill, 17... AC power supply, 18... Conductive ring, 19... Headstock, 20
... Conductive electron, 21 ... Conductive work, 22 ... Induction coil, 23 ... Control device.

Claims (1)

[Scope of utility model registration request] A tool holder is provided with a chuck portion for gripping a cutting tool on the outer end side and a fitting portion for a driving rotating spindle on the inner end side, and an electric current is provided that contacts the inner end surface of the cutting tool gripped by the chuck portion. A contact point and an electrically insulating part for electrically conducting the cutting tool and the fitting part through only the electrical contact point are provided, and the workpiece to be cut by the driving spindle and the cutting tool is provided. A cutting tool comprising: a power supply for passing a current through the electrical contacts of the tool holder and the cutting tool; and a detection means for detecting a state in which current no longer flows through the current path. Breakout detection device.