JPH0574747U - Spindle conductive device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a main shaft conductive device that is easy to maintain. A current carrying member, a holding unit for holding the current carrying member rotatably, and a biasing unit for the current carrying member, and the current carrying member is arranged in point contact with the rotation axis of the main shaft.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a conductive device for a spindle of a machine tool using a ceramic bearing.

[0002]

[Prior Art]

 FIG. 3 is a sectional view of the spindle head 1 of the machine tool. A spindle 2 is rotatably supported on the spindle head 1 by ceramic bearings 3 and 4. Reference numeral 5 is a draw bar arranged inside the main shaft 2, and has a collet 6 and a spring 7 for opening the collet 6 at one end, and a nut 8 at the other end. Reference numeral 9 is a spring for urging the draw bar 5. During processing, the drawbar 5 is pulled upward by the spring 9 in the drawing, and the collet 6 arranged at the tip is restricted by the hole 12 of the spindle 2 while the outer periphery of the collet 6 is held by the flange 11 of the tool 10. The tapered portion 13 of 10 is engaged with the tapered portion 14 of the main shaft 2. Reference numeral 15 is an air cylinder for removing the tool 10 from the spindle 2. That is, when the tool 10 is removed, compressed air is supplied from the port 16 to move the piston 17 downward, and the draw bar 5 is moved downward against the spring 9. Then, when the collet 6 is disengaged from the hole 12, the collet 6 is opened by the spring 7, the inner diameter of the collet 6 becomes larger than that of the flange portion 11, and the tool 10 can be detached from the spindle 2. Further, compressed air is supplied from the port 18 at the time of processing so that the piston 17 and the draw bar 5 are separated from each other. Reference numeral 19 denotes a copper contactor, one end of which is fixed to the spindle head 1 and the other end of which is in contact with the outer circumference of the spindle 2. Then, the static electricity generated in the ceramic bearings 3 and 4 is caused to flow through the contact 19 to the unillustrated ground of the spindle head 1, and the tool 10 and the machining that affect the life of the cutting edge of the tool 10 or the quality of the processed product. Prevents discharge phenomenon between products. Further, instead of providing the contactor 19, some of the plurality of balls forming the ceramic bearings 3 and 4 are made of steel balls to allow static electricity of the spindle 2 to flow to the earth of the spindle head 1. is there.

[0003]

[Problems to be solved by the device]

 However, in the case where the above-mentioned contactor 19 is used, not only the contact portion is abraded due to friction to reduce the reliability of conductivity, but also maintenance such as replacement of the nut 8 is troublesome. Also, in the case where the ball is a steel ball, the contact point moves, so that the surface of the steel ball is roughened and the reliability of the conduction is lowered, and the rotation resistance is increased. Also, maintenance was troublesome. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a highly reliable and easy-maintenance spindle conductive device.

[0004]

[Means for Solving the Problems]

 The above-mentioned problems are achieved by making the electromotive force, the holding means for rotatably holding the electromotive force, and the biasing means of the electromotive force, and bringing the electromotive force into point contact with the rotation axis of the main shaft.

[0005]

[Action]

 Since the conduction electrons make point contact with the rotation axis of the main shaft, the contact point does not move. Therefore, the roughness of the contact point due to conduction is reduced. Also, by reducing the applied pressure, wear due to friction is reduced.

[0006]

【Example】

 Hereinafter, a first embodiment of the present invention will be described with reference to FIG. The same parts as those in FIG. 3 are designated by the same reference numerals. Reference numeral 20 denotes a conduction electron, which is a steel ball. The point at which the conduction electrons 20 contact the drawbar 5 is the rotation axis of the drawbar 5, that is, the rotation axis of the main shaft 2. Reference numeral 21 is a seat for receiving the conduction electrons 20, which has conductivity, and has a recess 22 on the surface. The receiving seat 21 is fitted in the hole 24 of the piston 23 and is movable in the vertical direction. Reference numeral 25 is a spring having conductivity, which biases the conduction electron 20 toward the main shaft 2. It should be noted that the force with which the spring 25 urges the conducting electrons 20 may be a minimum force that allows the conducting electrons 20 to maintain contact with the drawbar 5. Reference numeral 26 is an earth wire, which connects the piston 23 and the cylinder 15. With the above configuration, static electricity generated in the ceramic bearings 3 and 4 flows to the spindle head 1. It should be noted that when the main shaft 2 rotates, the conduction member 20 rotates substantially integrally with the main shaft 2. Although the end surface of the draw bar 5 is a flat surface in this embodiment, a recess similar to the receiving seat 21 may be provided.

FIG. 2 shows a second embodiment of the present invention in which the drawbar 5 side is also provided with a conducting member 20, a receiving seat 21, and a spring 25. In addition, in the above two embodiments, the conduction electron 20 has a spherical shape, but it may have a shape capable of making point contact with the rotation axis of the main shaft 2, for example, a conical shape.

[0008]

[Effect of the device]

 As described above, according to the present invention, the conduction can be rotated even by making point contact with the rotation axis of the main shaft, so that wear due to friction is reduced and reliability can be improved. And, there is an effect that maintenance becomes easy.

[Brief description of drawings]

FIG. 1 is a diagram of a first embodiment of the present invention.

FIG. 2 is a diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 2 Spindle 5 Drawbar 20 Conductor 23 Piston 25 Spring

Claims (2)

[Scope of utility model registration request] 1. A current carrying member, a holding unit for holding the current carrying member rotatably, and a biasing unit for the current carrying member, wherein the current carrying member is arranged in point contact with the rotation axis of the main shaft. The main shaft conductive device. 2. The conductive device for a main shaft according to claim 1, wherein the means for holding the conduction is a drawbar pressurizing device.