JPS62159853A - Ball screw unit - Google Patents

Abstract

PURPOSE:To reduce the revolution transmission error by directly connecting a ball screw shaft and a nut onto each rotary driving member through a connection part and directly transmitting revolution. CONSTITUTION:The connecting shaft part 22 of a ball screw shaft 1 and a shaft 23 are connected and fixed through a coupling 21. A coupling 36 is inserted and engaged with the connection receiving part 37 of a nut 2. Therefore, the connecting shaft part 22 and the connection receiving part 37 of the nut 2 are manufactured with high precision, and the ball screw shaft 1 and the nut 2 are directly connected free from the center deflection of the shafts 23 and 38 of the driving motors M1 and M2. Therefore, the revolution of the driving motors M1 and M2 is directly transmitted to the ball screw 1 and the nut 2, and each revolution precision of the ball screw 1 and the nut 2 can be kept favorably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ball screw unit 1-, and more particularly to a ball screw unit in which a nut screwed into a ball screw sleeve is improved.

[Prior Art] Conventionally, as this type of ball screw unit, there is one shown in FIG. 4, for example. This is ball screw shaft 1
While screwing together the nut 2 through a large number of balls 3,
The nut 2 is pivotally supported by a pair of bearing members 4 (specifically, 4a and 4b) which also serve as a frame, and a fixing flange 6 is provided protruding from the outer ring 5 of one of the bearing members 4a. A connecting flange 7 is also provided on the negative side of the outer peripheral surface of the connecting flange 7, and a gear 8 for torque transmission is carved on the peripheral surface of this connecting flange 7. In addition, in Fig. 4, reference numeral 9
10 is a holding space that is interposed between a pair of bearing members 4 and holds each bearing member 4 in pressure contact with a predetermined portion of the outer peripheral surface of the nut 2; 10 is a holding space that closes the gap between the ball screw shaft 1 and both ends of the nut 2; It is a dust seal.

According to this type, the nut 1-2 is rotatably supported by the frame, and the ball screw shaft 1 and nut 2 are rotated relative to each other due to the relative rotation between the ball screw shaft 1 and the nuts 1-2. make a reciprocating motion.

Therefore, by using such a conventional ball screw unit, it is possible to construct a moving table device capable of fine movement and rapid movement, as shown in FIG. 5, for example.

This movable table device has a movable table 12 movably disposed on a fixed base 11. The vicinity of both ends of a ball screw shaft 1 is rotatably supported by bearing members 13, 14, and one end of the ball screw shaft 1 is rotatably supported. The part 1a is connected to the shaft part 16a of one of the drive motors 16 via a coupling 15,
The outer ring 5 of the bearing member 4 serving as the frame body is fixed to the movable table 12 side via the fixed 7 flange 6, and the transmission gear 17 is meshed with the gear 8 portion, and the other fixedly installed on the movable table 12. The transmission gear 17 is fixed to the shaft 18a of a drive motor 18.

In such a movable table device, if the rotational directions of the drive motors 16.18 are reversed, the movable table 12 can be fast-forwarded in a predetermined direction, while the drive motors 16.18 can be rotated in the same direction. By making the rotation speed slightly different depending on the direction of rotation, the movable table 12 moves slightly in a predetermined direction.

[Problems to be Solved by the Invention] However, in such a conventional ball screw unit, since the rotation center of the nut 2 and the rotation center of the drive motor 18 are offset, In the process of transmitting the rotational force from the drive motor 18 to the nut 2,
The rotation M degree of the nut 2 varies due to the play in the gear 8, and the rotational movement of the nut 2 tends to become unstable accordingly. For this reason, for example, in a movable table device such as J shown in FIG. 5, it becomes difficult to accurately feed the movable table 12, and fine movement and rapid feed cannot be performed with high precision. This causes problems.

[Means for Solving the Problems 1] The present invention has been made by focusing on the above-mentioned problems, and it is possible to make the feed accuracy extremely high, thereby improving fine movement and rapid feed operations. The present invention provides a ball screw unit that can be used to control viscosity.

That is, the present invention is a ball screw unit in which a nut is screwed onto a ball screw shaft via a ball, and the nut is pivotally supported on a frame, and one end of the ball screw shaft is driven to rotate on one side. A cylindrical extension is formed at one end of the nut to protrude from at least the opposite end of the ball screw shaft, and the end of the extension is connected to the other rotary drive member. An angular contact bearing is interposed between the frame and the nut.

In such technical means, the basic configuration of the ball screw unit may be modified as appropriate, but at least the members that pivotally support the nuts 1 to 1 on the frame should be It is necessary to use angular contactors 1 to bearings to support the cart.

Preferably, this angular contact bearing is of the type that does not have an inner ring and has a ball rolling surface formed directly on the outer peripheral surface of the nut. In addition, the design may be changed as appropriate regarding the length of the extension part extending to one end side of the above-mentioned Nara 1, but at least the part protruding from the end of the ball screw shaft should be connected to other rotary drive members. It is necessary to design the area in such a way that the

[Operation] According to the above-mentioned technical means, since the ball screw shaft and the nut are directly connected to each rotary drive member through the respective connecting portions, the rotation of each rotary drive member is directly connected to the ball screw shaft and the nut. As a result, errors in rotation transmission to the ball screw shaft and nut are almost eliminated.

Further, the nut 1- is pivotally supported on the frame via the angular contactor 1-bearing, and the inner and outer peripheral surfaces of the nut are provided with a ball rolling surface between the ball screw shaft and the bearing. Since the ball rolling surfaces of are manufactured coaxially, the coaxiality between the ball screw shaft and the nuts 1 to 1 is given as having good viscosity.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the accompanying drawings.

In the embodiment shown in FIG. 1, the ball screw unit is
A ball screw shaft 1, a nut 2 screwed onto the ball screw shaft 1 through a large number of balls 3, and a nut h2
and a frame body 4 which is pivotally supported via an angular contact bearing 45.

In this embodiment, the ball screw shaft 1 has a threaded portion A in all parts except its both ends, and one end of the ball screw shaft 1 has a threaded portion A as a connecting portion with one drive motor M1 (see FIG. 2), for example. A connecting shaft portion 22 is formed to be inserted and locked into a coupling 21 for use.

The nut 2 also includes a nut main body 30 and an extension 35 integrally formed on one end side of the nut main body 30.
It is made up of. The nut main body 30 has an appropriate ball rolling surface 31 recessed on its inner peripheral surface so that the balls 3
The ball rolling surface 32, which is a component of the angular contact bearing 45, is recessed on both sides of the outer peripheral surface. Furthermore, the extension portion 35 of the nut 2 is formed in a cylindrical shape,
When the non-extension side end of the nut main body 30 is located at the end of the threaded portion A of the ball screw shaft 1, it is arranged to protrude from one end of the ball screw shaft 1, and the inner periphery of the extension 35. A connection receiving part 37 for inserting and locking a connection coupling 36, for example, is formed at the end of the surface as a connection part with the other drive motor M2 (see FIG. 2). The shaft 38 of the drive motor M2 is connected and fixed to the shaft.

Further, the frame body 4 has a diameter on one end side of the extension portion 35.
It consists of a cylindrical outer tube 40 set corresponding to the outer diameter of the outer tube 40, and a fixed flange 41 for attachment is formed on one side of the outer tube 40 to protrude outward. Further, an angular contact bearing 45 is interposed between the inner circumferential surface of the outer cylinder 40 and the nut main body 30,
This bearing 45 includes a ball raceway surface 32 formed on the outer circumferential surface of the nut main body 30, and a ball raceway surface 32 formed on the outer peripheral surface of the nut body 30.
The outer ring 47 is attached to the inner peripheral surface of the outer 1i40 and holds the balls 46 so as to be able to roll along with the ball rolling surface 32. In FIG. 1, reference numeral 42 denotes a holding plate that is freely attached to the opening on one end of the outer cylinder 40 and presses down the nut 2 and bearing 45 that are incorporated into the outer cylinder 40, and 43 is the ball screw shaft 1. This is a dust seal interposed between the nut main body 30 and the non-extension side end.

Therefore, when manufacturing the ball screw unit according to this embodiment, the ball screw shaft 1, the necks 1 to 2, the outer cylinder 40 as the frame 4, and the angular contact 1-bearing 4
The nut 2 is screwed onto the ball screw shaft 1 via a large number of balls 3, and the frame body 4 is fitted with the
The knot 2 may be inserted through the bearing 45. In this case, the method for manufacturing the nut 2 is as follows: After supporting both sides of the cylindrical nut manufacturing material with centering members, one side cylindrical part of the nut manufacturing material (the nut 2
(equivalent to the extension part 35) The outer peripheral surface is ground to form a processing reference surface, and then the inner peripheral surface of the end of the extension part 35 is ground l1lN using the processing reference surface as a reference to form the connection receiving part 37. Furthermore, with reference to the processing reference plane, a ball rolling surface 31 is ground on the inner circumferential surface of the other cylindrical portion of the nut manufacturing material (corresponding to the nut 2 neck/main body portion 30), and at the same time,
A procedure is adopted in which the ball rolling surface 32 of the angular contact bearing 45 is ground on its outer peripheral surface. By adopting such a manufacturing procedure, the axis of the connecting shaft portion 37 formed at the end of the extension portion 35 of the nut 2 and the inner circumferential surface of the nut body portion 30 of this nut 2 can be The axes of the ball rolling surface 31 and the ball rolling surface 32 formed on the outer circumferential surface of the nut main body 30 can be aligned accurately.

In order to explain the operation of such a ball screw unit, a moving table device in which a ball screw unit is incorporated will be taken as an example. As shown in FIG.
A movable table 12 is movably disposed on the movable table 12 via a guide mechanism (not shown).One drive motor M1 is fixedly installed on the movable table 12, and the fixed base 1
The other drive motor M2 is fixedly installed on top of the ball screw shaft 1, and the frame body 4 is fixedly installed on the fixing base 11 side, and the connecting shaft part 22 of the ball screw shaft 1 and the shaft 23 of the drive motor M1 are cupped. A coupling 36 is inserted and locked into the connection receiving portion 37 of the nut 2, and the ends of shirts 1 to 38 of the other drive motor M2 are connected and fixed to this coupling 36. It was designed to do so.

In such a movable table device, the movable table 1
2, when finely moving the motors M and M2,
It is only necessary to make the directions of rotation of the two parts the same, and to make the number of revolutions slightly different. At this time, ball screw shaft 1
and the nut 2 rotate in accordance with the rotational motion of each of the drive motors M and M2, but since there is a slight difference in rotation between them, the ball screw shaft 1 is moved in a predetermined direction by an amount corresponding to the difference. This will result in a slight movement.

On the other hand, if the movable table 12 is to be moved rapidly, the rotational directions of the drive motors M1 and M2 may be reversed, and the number of rotations of each drive motor may be set to a certain high value. At this time, since the ball screw shaft 1 and the nut 2 are mutually reversed by the respective drive motors M and M2, the ball screw shaft 1 is rotated by the number of rotations of each drive motor relative to the nut 2. It will rotate at high speed,
Along with this, the movable table 12 is rapidly moved.

Next, the performance of the ball screw unit according to this example will be evaluated.

First of all, since the connecting shaft portion 22 of the ball screw shaft 1 and the connecting receiving portion 31 of the nut 2 are manufactured with high precision, the ball screw shaft 1 and the nut 2 are connected to the shafts 23 and 38 of the respective drive motors M1 and M2. It is directly connected to the center without any misalignment. Therefore, the rotation of each drive motor M, M2 is directly transmitted to the ball screw shaft 1 and nut 2,
The rotation accuracy of the ball screw shaft 1 and the nut 2 is maintained at a good level.

Second, ball rolling surfaces 31.32h<32h are formed coaxially with high accuracy on the inner peripheral surface and outer peripheral surface of the nut main body 30,
Since the ball screw shaft 1 and the nut 2 are screwed together through the balls 3, and the nut 2 is supported by the frame 4 through the angular contact bearing 45, the ball screw shaft 1 and the nut 2 are reliably coaxial. Placed. therefore,
The rotation centers of the ball screw shaft 1 and the nut 2 and the rotation centers of the drive motors M1 and M2 coincide with each other, and the rotation of the drive motors M1 and M2 is transmitted to the ball screw @1 and the nut 2. In this way, a situation in which the ball screw shaft 1 and the nut 2 move based on misalignment is reliably avoided.

As a result, 111 of the ball screw shaft 1 and the neck 1-2
The rotational movement becomes accurate, and the movable table 12
The three works to be sent will be set to high precision.

In configuring the movable table device, the movable table device is not limited to that shown in FIG. 2. For example, as shown in FIG. is fixedly installed on the fixed base 11 side, and the oak]・2
The other drive motor M2 connected to the movable table 12
The frame body 4 is fixedly installed on the side, and the frame body 4 is mounted on a movable table 12.
It may be fixedly provided on the side.

[Effects of the Invention] As explained above, according to the ball screw unit according to the present invention, the rotational drive member can be directly connected to the ball screw shaft and the nut screwed to the ball screw shaft, and the ball screw Since the coaxiality between the shaft and the nut is maintained, it is possible to almost eliminate rotational transmission errors and imaging based on misalignment during the process of transmitting rotational force from each rotational drive member to the ball screw shaft and nut. Therefore, the relative rotational movement of the ball screw shaft and the nut can be made more accurate. Therefore, when a moving mechanism is constructed using this ball screw unit 1-, the member to be moved can be finely moved or rapidly moved with high precision.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of an embodiment of a ball screw unit according to the present invention, FIG. 2 is an explanatory diagram showing an example of a movable table device using the ball screw unit according to the embodiment, and FIG. The figure is an explanatory diagram of a modification of the moving table device shown in Figure 2, Figure 4 is an explanatory cross-sectional view showing an example of a conventional ball screw unit, and Figure 5 is a movement using the conventional ball screw unit. It is an explanatory view showing an example of a table device. [Explanation of symbols] (M, M2)... Drive motor (rotary drive member) (1)
... Ball screw shaft (2) ... Nut (3) ... Ball (4) ... Frame (22) ... Connection shaft (connection part) (35) ... Extension part ( 31)...Connection receiving part (connection part) (45)...Angular contact bearing patent applicant Hiroyo Teramachi Patent attorney Katsuo Naruse (2 others) Akira Te'' and Tadashi Neichi Written in 1986 December 11th

Claims (1)

[Claims] In a ball screw unit in which a nut is screwed onto a ball screw shaft via a ball, and the nut is pivotally supported on a frame, one end of the ball screw shaft is formed as a connecting portion with one rotational drive member. One end of the nut is formed with at least a cylindrical extension projecting from the opposite end of the ball screw shaft, and the end of the extension is formed as a connection part with the other rotational drive member, and the frame A ball screw unit characterized by having an angular contact bearing interposed between the body and the nut.