JPS58120439A - Spindle stock equipped with motor built-in - Google Patents

Abstract

PURPOSE:To obviate the thermal conduction to the front of a spindle stock and improve the working accuracy by cantilever-supporting a stator from behind a motor, in case of a motor buit in a spindle stock. CONSTITUTION:A spindle 10 integrally formed with a rotor 22 is supported by a front bearing box 18a and a rear bearing box 18b through bearings 14 and 16. A stator frame 24B integrally formed with a stator 24 is cantilever-supported from behind a spindle stock frame 32. A ventilating hole 28 is formed on the stator frame 24a, and the cooling air is introduced as indicated by an arrow from an air introducing hole 34 formed on the spindle frame body 32. Thus, the conduction of the heat generated on the stator 24 toward the front of the spindle is reduced, and the stator 24 itself is cooled by the air introduced-in.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a headstock for a machine tool, and more particularly to a headstock with a built-in motor, in which a motor rotor is attached to a single-rotation spindle supported by a bearing, and a circular stator is provided surrounding the rotor. The headstock Vcl with a built-in motor has an improved structure to avoid thermal deformation of the headstock due to the heat generated by the motor.
A headstock with a built-in motor is often used as a compact headstock, which eliminates the need for auxiliary machinery for a rotation transmission mechanism by directly attaching a rotational drive motor, especially an AC motor, to the main shaft of a machine. In this type of headstock with a built-in motor, the heat generated from the rotary drive motor causes thermal deformation of the main spindle, bearing sleeve, and various mechanical parts of the headstock. A gripping chuck is attached to grip the workpiece, resulting in a decrease in machining accuracy during machining. Therefore, various improvements have been proposed to avoid the occurrence of such thermal deformation caused by heat generation in the motor, and in the case of AC motors, it is believed that the stator, which has an excitation winding, is a major cause of heat generation. Therefore, a structural design that avoids the heat generated by the stator from being transferred to the various mechanical parts is required. In this case, if heat transfer occurs particularly in the front part of the spindle where tools and workpieces are attached or held, it will also cause thermal deformation of these tools or workpieces, resulting in deterioration of machining accuracy. A structure is required to prevent the transfer of motor-generated heat to the motor.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a headstock with a built-in motor that prevents heat transfer from the motor stator to the front part of the main shaft in a headstock with a built-in AC motor.

According to the present invention, in a Tanabata built-in headstock in which a rotor is attached to a bearing-supported main shaft and a stator is provided surrounding the rotor, the front part of the main shaft is equipped with tools or a workpiece gripping chuck. and a rear part of the main shaft opposite to this in the axial direction, the stator is arranged isolated from the front part, and the stator is held cantilevered by a main shaft frame provided in the rear part. It is something to do. Hereinafter, the present invention will be explained in detail based on the accompanying drawings.

The figure is a sectional view showing an embodiment of a headstock with a built-in motor (AC motor) according to the present invention. A tapered hole 12m is provided to which a ring tool or a chuck for gripping a workpiece is attached, and the rear part 12b is formed as a part to which a rotation detector for controlling the rotation of the main shaft 100 is attached. Front part 12, rear part 1
2b is supported by bearings 14, 14 and 16; in the illustrated example, the bearing 14 is formed of a roller bearing for supporting a radial load, and the bearing 16 is formed of a thrust bearing for supporting a thrust load. These bearings 14.16 are housed in a bearing box 188.18b and are further covered with a cover 20m long.
, 20b prevent dust from entering into the bearing 14. The bearing boxes 18m and 18b have a structure in which they are integrally formed with a headstock frame 32 or are mounted and fixed concentrically, and the headstock is attached to a machine tool base or the like via this headstock frame 32. It will be done. A rotor 22 of a rotational drive AC motor is fixedly fixed in the axial direction and circumferential direction approximately at the center of the main shaft 10 by suitable fixing means such as a wedge.

Further, a Σ-yonis data 24 is disposed on the outside of the rotor 22, concentrically with the rotor 22 and surrounding the rotor 22 with a small gap interposed therebetween. This stator 24 has a cover 26a on the front part, and the stator 24. The stator frame 24aK is integrally formed with the stator frame 24aK, and is attached to the rear surface of the spindle frame 32 in a cantilevered manner. Stator frame 241
After proper centering of the rotor 22 and stator 24, the rotor 22 and the headstock frame 32 are fixedly fixed by appropriate fixing means 36 such as bolts.

That is, according to the present invention, the stator 24 of the rotational drive AC motor is attached to the surface of the frame 32 at the rear part of the headstock by the stator frame 2411, and the stator 24 is attached to the surface of the frame body 32 at the rear part of the headstock, and the stator 24 is attached to the surface of the frame body 32 at the rear part of the headstock. 10 taper holes 1
The structure is such that the heat generated by the stator 24 is not directly transferred to tools or the like mounted on the stator 2a by thermal conduction. Incidentally, a ventilation hole 28 is formed in the stator 24 and the stator frame 24M, and an appropriate number of air introduction holes 34 are provided at the rear end of the spindle frame 32, so that air can be introduced through the air introduction hole 34. The cooling air flow is transferred to the spindle frame body 3.
The air is introduced into the ventilation hole 28 via the air @ 30 between the stator 2 and the stator 24, and is discharged to the outside by the cooling fan 40 from the duct 42 via the through hole 38 formed on the rear surface of the frame 32. By providing a cooling mechanism, the system stator 24 is also cooled by heat absorption. Therefore stator 2
4, the stator 24 itself receives a cooling effect due to this heat-absorbing cooling, and the heat transmitted to the various S components of the headstock by thermal conduction also leaves a shadow 1 on the front part 12 of the main shaft 10. Since the structure is such that the heat deformation does not occur, the deterioration in machining accuracy due to the thermal deformation mentioned above can be avoided.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of a headstock with a built-in motor according to the present invention. lO...main shaft, 12...front part, 12b...rear part, 14.16...bearing, 22...rotor, 24...
...Stator, 2421...Stator frame, 32...
Main spindle frame, 36...fixing means. Patent applicant Fujitsu Fanuc Ltd. Patent application agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Kyosuke Tsuchinakayama Patent attorney Akira Yamaguchi

Claims (1)

[Claims] 1. In a headstock with a built-in motor in which a rotor is attached to a main shaft supported by a bearing and a stator is provided surrounding this rotor, the front part of the main shaft where tools or workpiece gripping chucks are attached, and the front part of the main shaft in the axial direction A headstock with a built-in motor, in which the stator is arranged to be isolated from the front part of the opposite rear part of the main shaft, and the stator is held cantilevered by a frame provided in the rear part.