JPH02146944A - Ball screw through servomotor - Google Patents

Abstract

PURPOSE:To reduce conduction of heat, generated in a motor, to a ball nut by providing a nut housing hole part, which can receive a main unit part of the ball nut having a maximum size, while mounting the ball nut to a cylindrical shaft through an interposing member. CONSTITUTION:A motor shaft 10 is formed in a hollow cylindrical shape, and its one end part 12 forms a nut housing hole part 16 which can receive the main unit part 22A of a ball nut 20A of maximum size. This hole part 16 is set in its hole bore a little larger than the outside diameter of the main unit part 22A of the ball nut 20A, providing an air gap for increasing resistance of heat conduction from the shaft 10 to the ball nut 20A. Further interposing members 26A, 26B are used corresponding to individual ball nuts 20A, 20B. Accordingly, the ball nut 20B of smaller size can be fixed to one end part 12 of the shaft 10. In this way, the quantity of heat, generated in the inside of a motor and conducted to the ball nuts 20A, 20B, can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a ball screw shaft/ball nut mechanism that is a driving force transmission mechanism of a machine tool, etc., in which the ball screw shaft is inserted and the ball nut is fixed. The present invention relates to a servo motor having a shaft.

[Conventional technology]

Conventionally, when directly connecting a ball screw shaft/ball nut mechanism to a motor shaft, a method has been adopted in which the ball screw shaft is inserted through the motor shaft and the ball nut is fixed to the motor shaft.

In this case, conventionally, the ball nut was directly fixed to the motor shaft using a threaded part or the like.

[Problem to be solved by the invention]

However, in order to directly fix a ball nut to a motor shaft, the shaft shape must be designed to match the dimensions and form of the ball nut, and the motor housing etc. must also be designed accordingly. The problem is that it must be designed to do so. Furthermore, when the ball nut is directly attached to the motor shaft, there is a problem in that the heat generated inside the motor is directly conducted to the ball nut and further to the ball screw shaft, resulting in deterioration of feeding accuracy due to thermal expansion.

Therefore, in order to solve these problems, the present invention makes it possible to fix ball nuts of various sizes to a fixed motor shaft, and to reduce the conduction of heat inside the motor to the ball nuts. The purpose of the present invention is to provide a ball screw penetrating servo motor that has the following characteristics.

[Means to solve the problem]

In view of the above object, the present invention provides a servo motor having a cylindrical shaft into which a ball screw shaft can be inserted through the center of the shaft, in which one end of the cylindrical shaft is
Among a series of ball screw shafts and ball nuts having various sizes, the shaft has a nut accommodating hole of a size that can accommodate the main body of the ball nut having the largest size, and the shaft has the nut accommodating hole. The one end portion includes a first engaging portion provided corresponding to each of the ball nuts of various sizes and capable of fastening the corresponding ball nuts; A ball screw penetrating servo motor is provided, in which a ball nut is attached to a cylindrical shaft via intervening members each having a second engaging portion.

[For production]

One end of the shaft is provided with a nut housing hole that can accommodate the main body of the ball nut with the largest size among the ball screw shafts and ball nuts that are planned to be used, and therefore can accommodate any of the ball nuts that are planned to be used. can. Furthermore,
Due to the use of intervening members corresponding to individual ball nuts, it is possible to fix smaller ball nuts to one end of the shaft. In addition, there is a gap between the surrounding wall of the nut receiving hole and the main body of each ball nut, and by using an appropriate intervening member, the amount of heat generated inside the motor transferred to the ball nut can be reduced. can be reduced.

〔Example〕

The present invention will be described in more detail below based on embodiments shown in the accompanying drawings. Identical parts in FIG. 1 and FIG. 2 are given the same reference numerals. It is assumed that the ball screw shaft 18A and the ball nut 2OA shown in FIG. 1 are of the maximum size planned to be used in this design. The motor shaft 10 is formed into a hollow cylindrical shape with a through hole 14 provided in the center over its entire length. This one end portion 12 is formed with a nut accommodating hole portion 16 having a hole diameter large enough to accommodate the main body portion 22A of the largest size ball nut 20A. Furthermore, the hole diameter of this hole portion 16 is the same as that of the shaft 10.
In order to increase the heat conduction resistance from the ball nut 20A to the ball nut 20A, the outer diameter is set to be somewhat larger than the outer diameter of the main body 22A of the ball nut 2OA, and a gap is provided.

A ball screw shaft 1 is included in the motor shaft 10 having the above structure.
Insert ball nut 2OA and ball nut 20A.
A is fixed to one end 12 of the shirt 10 via its flange 24A. In this case, a small ball screw shaft 18B and a ball nut 20B as shown in FIG. 2 are inserted into the shaft 10, and the ball nut 20B is inserted into the end 12 of the shaft that is the same as the end 12 of the shaft shown in FIG. In order to make the flange portion 24B threadable, an intervening member is required.

Flange part 24A of large size ball nut 2OA
The center position P1 of the hole for inserting a screw component provided in the flange part 24 of the small ball nut 20B.
Center position IP3 of the hole for inserting screw parts provided in B
are, of course, at different radial dimensional positions relative to one end 12 of motor shaft 10. Therefore, it is necessary to prepare the intervening member 26A or 26B depending on the size of the ball nut 2OA or 20B. These intervening members 26A, 2
6B is provided with a tapped hole at the radial dimension position P2, which is provided in the tip surface of the one end 12 of the motor shaft lO, and which engages with other threaded parts, and each of the intervening members 26A,
26B is provided with a screw component insertion hole corresponding to the same radial dimension position P2. In addition, each flange portion 24A,
A screw hole is provided in each intervening member 26A, 26B corresponding to each radial position Pi, P3 of 24B.

If the intervening member is configured as described above, first, a threaded part is used at the radial dimension position P2, and the intervening member 26A (26
B) is fastened and fixed to one end 12, and then the radial dimension position P
Use other screw parts for L (P3) to attach ball screw 2O.
The flange portion 24A (24B) of A (20B) can be fastened and fixed to the intervening member 26A (26B). For example, the radial position Pi of the intervening member 26A shown in FIG.
A threaded hole corresponding to P2 and a threaded component insertion hole corresponding to the other radial dimension position P2 are respectively the first engaging part and the second engaging part described in the claims column. be. Furthermore, even if the above-mentioned radial dimensional positions P1 and P2 (P3 and P2) are approximately the same, by appropriately shifting the positions of the actual tapped holes and insertion holes in the circumferential direction, it is possible to Different types of holes do not interfere.

The inner diameter dimensions of the center holes 30A and 30B of the intervening members 26A and 26B are such that the heat generated inside the motor is absorbed by the ball nut 20A.

20B to prevent conduction to the main body 2 of each ball nut.
It is desirable to design the outer diameter to be somewhat larger than the outer diameter of 2A and 22B. However, a ball nut 2OA (20B) is attached to the motor shaft 1 at an appropriate position in the circumferential direction.
0 and the body part 2 of the ball nut to hold it concentrically with
It is necessary to provide a centering protrusion that contacts 2A (22B). With this configuration, the intervening member 2
6A, end face 28A of 26B.

Since only the ball nuts 28B are in contact with the ball nuts 2OA and 20B, the heat generated inside the motor is transferred to the shaft 10.
The amount of heat conducted to the ball nut via the ball nut can be reduced. Furthermore, although the motor shaft IO is made of a material with relatively high thermal conductivity such as ordinary carbon steel, the intervening member 26A
, 26B are made of a material with low thermal conductivity such as ceramics, the amount of heat transferred to the ball nut can be further reduced. Also, compared to the conventional method, the number of parts called intervening members has increased, but these are small parts.
Compared to preparing only the same type of motor shaft and housing, this results in a significant cost reduction.

[Effects of the Invention] As is clear from the above description, according to the present invention, ball nuts of various sizes can be fixed to the motor shaft without changing the motor shaft or housing, and costs can be reduced. At the same time, it is possible to reduce the amount of heat generated in the motor transferred to the ball nut.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of one end of the shaft of the servo motor according to the present invention, with a large ball screw shaft and ball nut attached, and Fig. 2 is a longitudinal sectional view of a small ball screw shaft and balls. FIG. 3 is a longitudinal cross-sectional view of one end of the shaft of the servo motor according to the present invention with a nut attached. DESCRIPTION OF SYMBOLS 10... Motor shaft, 12... One end of shaft, 16... Nut accommodation hole, 18A, 18B... Ball screw shaft, 20A,
20B...ball nut, 26A, 26B...intervening member, Pi, P3...position of the first engaging portion for attaching the ball nut to the intervening member. P2...Position of the second engaging part for attaching the intervening member to one end of the shaft.

Claims (1)

[Claims] 1. In a servo motor having a cylindrical shaft through which a ball screw shaft can be inserted through the center of the shaft,
One end of the cylindrical shaft has a nut receiving hole having a size capable of accommodating the main body of the ball nut having the largest size among a series of ball screw shafts and ball nuts having various sizes, and the nut At one end of the shaft having a housing hole, a first engaging portion is provided corresponding to each of the ball nuts of various sizes and capable of fastening the corresponding ball nuts; A ball screw penetrating servo motor characterized in that a ball nut is attached to a cylindrical shaft via intervening members each having a second engaging portion that can be fastened to one end.