JPH074490A - Movable bearing device of feed screw - Google Patents

Abstract

PURPOSE:To rotate a feed screw at a high speed even though the feed screw has a long size and a small diameter, by holding the feed screw by fitting a rotatable nut to a rolling bearing provided on a bearing bracket slidably installed on a linear guide. CONSTITUTION:When a body to be moved 16 is moved from the left side to the right side of a feed ball screw 2 by a motor 8, the body to be moved 16 moves while adsorbing a bearing bracket 22a with a permanent magnet 36a. When the body to be moved 16 is moved to the right end passing through the middle point of the feed ball screw 2, the bearing bracket 22a adsorbed to the body to be moved 16 theretofore is abutted on a stopper 20, the adsorption with the permanent magnet 36 is cut off, and it is left at the middle point of the feed ball screw 2. At the same time, the body 16 is moved to the right end of the feed ball screw 2 while abutting on a different bearing bracket 22b. When such a body 16 is moved reciprocating, the middle point of the feed ball screw 2 is held securely by the bearing brackets 22a and 22b through a ball nut 32, and a rolling bearing 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving bearing device for a lead screw.

[0002]

2. Description of the Related Art A mechanism in which a moving body is screwed onto a feed screw and the moving body is linearly reciprocated by forward or reverse rotation of the feed screw is generally used in machine tools and factory automation lines. ing.

However, the technique for supporting the intermediate portion of the feed screw has not been developed. This is because it is difficult to support the intermediate portion of the feed screw while avoiding interference with the movable body.

[0004]

Since the intermediate portion of the conventional feed screw is not supported except for the portion supported by the movable body,
When the feed screw rotates at a high speed, a resonance phenomenon between the rotation number and the natural frequency of the feed screw causes a rapid increase in the axial deflection of the intermediate portion of the feed screw, and in some cases causes axial destruction. Such a danger is likely to occur particularly when the body to be moved moves close to the end of the feed screw and the unsupported portion of the feed screw becomes long.

If the shaft diameter of the feed screw is increased, it can withstand a high speed rotation to some extent, but a large increase in cost is unavoidable and the range of use is limited. For this reason, it has been virtually impossible to move the object to be moved over a long distance at high speed.

An object of the present invention is to provide a movable bearing device which can rotate at high speed even with a long and thin feed screw.

[0007]

A feature of the present invention is that a linear guide is arranged in parallel with a feed screw, a bearing bracket is slidably attached to the linear guide, and a rolling bearing arranged in the bearing bracket is provided. Fit the nut rotatably and insert the feed screw into this nut to support the feed screw.
Moreover, the bearing bracket is located at a position separated from the body to be moved by the positioning means.

[0008]

Since the nut is rotatably supported by the rolling bearing, even if the feed screw rotates, the nut simply idles and the bearing bracket does not move. The bearing bracket is located at a position separated from the movable body by the positioning means,
That is, it is placed on the unsupported portion of the feed screw, and the same portion is supported via a nut, and in turn supported by a linear guide. This prevents bending of the intermediate portion of the feed screw due to centrifugal force during high-speed rotation.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the present invention. In the figure, 2 is a feed ball screw, 4 and 6 are fixed bearings that rotatably support both ends of the feed ball screw 2, and 8 is a pulley 10 and 12.
And a motor for rotationally driving the feed ball screw 2 via the toothed belt 14, and 16 is one end 16a of the feed ball screw 2.
Is a movable body to which is screwed. The movable body 16 is slidably supported by a guide member (not shown).

A linear guide 18 parallel to the feed ball screw 2 is disposed above the feed ball screw 2, and both ends of the linear guide 18 are supported by upper ends of fixed bearings 4 and 6. A stopper 20 is arranged in the middle of the linear guide 18, and the linear guides 18 on both sides of the stopper 20 are
The upper ends of the pair of bearing brackets 22a and 22b are shown in FIG.
As shown in (B), the dovetail 24 and the dovetail groove 26 are slidably attached due to the engaging relationship.

A bearing accommodating hole 28 is formed at the lower ends of the bearing brackets 22a and 22b as shown in FIG. 2A, and the outer ring 30 of the rolling bearing 30 is formed on the inner peripheral surface of the bearing accommodating hole 28.
a is fitted. A ball nut 32 is fitted on the inner peripheral surface of the inner ring 30b of the rolling bearing 30, and the feed ball screw 2 is inserted and screwed into a screw hole 34 of the ball nut 32.

As shown in FIGS. 1A and 1B, a pair of permanent magnets 36a and 36b are fixed to the left and right sides of the upper end 16a of the movable body 16. On the other hand, the bearing brackets 22a and 22b are made of a magnetic material such as iron.

The movable bearing device for the feed ball screw 2 is constructed as described above, and when the motor 8 is normally or reversely rotated, the movable body 16 is moved along the feed ball screw 2 in FIGS. 1 (A) and 1 (B). Move left or right. Both ends of the feed ball screw 2 are supported by fixed bearings 4 and 6, and an intermediate portion thereof is supported by a movable body 16.

When the moving body 16 moves from the left end to the right end of the feed ball screw 2 as shown in FIG.
6 moves while the bearing bracket 22a is attracted by the permanent magnet 36a.

When the moving body 16 moves to the right end beyond the intermediate portion of the feed ball screw 2, the moving body 16 is moved until this time.
Bearing bracket 22 attracted and brought by
The a comes into contact with the stopper 20 and cannot proceed any further, the attraction force with the permanent magnet 36a is cut off, and it is left in the intermediate portion of the feed ball screw 2. At the same time, the moving object 1
6 contacts another bearing bracket 22b, and moves to the right end of the feed ball screw 2 while pushing this bearing bracket 22b.

When the movable body 16 reciprocates along the feed ball screw 2 in this manner, either one of the bearing brackets 22a or 22b is always left in the middle of the feed ball screw 2 and the feed ball screw 2 The intermediate portion of the bearing bracket 22 via the ball nut 32 and the rolling bearing 30.
It is supported by a and 22b, and by the linear guide 18.

Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the bearing bracket 22
A sub-feed ball screw 38 arranged in parallel with the feed ball screw 2 is used to position a and 22b apart from the moving body 16. A pair of gears 40, 42 meshing with each other are attached to one end of each of the feed ball screw 2 and the sub feed ball screw 38 protruding outside the fixed bearing 4. The screw pitch of the auxiliary feed ball screw 38 is the same as that of the feed ball screw 2, but the gear ratio of the gears 40 and 42 is 1
It is / 2. The bearing brackets 22a and 22b are screwed to the feed ball screw 2 as in the first embodiment.
The auxiliary feed ball screw 38 is also screwed. The intermediate portion of the auxiliary feed ball screw 38 is supported by a fixed bearing bracket 44 that hangs from the intermediate portion of the linear guide 18. At the lower end portion of the fixed bearing bracket 44, a freely rotatable nut (not shown) is attached with the same configuration as in FIG.

In this movable bearing device, the bearing brackets 22a, 2a are moved at half the moving speed V of the moving body 16.
2b moves in the same direction as the moving body 16. Moved object 16
When the bearing ball 22a reaches the middle portion of the feed ball screw 2, the bearing bracket 22a moves from the left end to the right by ¼ of the length of the feed ball screw 2, and the other bearing brackets 22b move the length of the feed ball screw 2 Move 1/4 from the middle to the right.
When the moving body 16 moves to the right end of the feed ball screw 2, the bearing bracket 22a reaches the middle portion of the feed ball screw 2, and the other bearing brackets 22b move to the feed ball screw 2.
Move to the right end of.

As described above, the unsupported portion of the feed ball screw 2 does not exceed half of the length of the feed ball screw 2 at the longest.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, a pantograph 46 arranged parallel to the feed ball screw 2 is used to position the bearing brackets 22a and 22b apart from the movable body 16. Both ends of the pantograph 46 are supported by the upper ends of the fixed bearings 4 and 6. The upper end of the movable body 16 is connected to the pin at the intersection at the center of the pantograph 46 via a connecting member 50. Three bearing brackets 48a to 48f are provided on both sides of the movable body 16, respectively. These bearing brackets 48a to 48f are connected to a pin at the intersection of the pantograph 46 via a connecting member 52.
The bearing brackets 48a to 48f are arranged at equal intervals on the one side of the movable body 16 with respect to the pantograph 46, but they do not necessarily have to be at equal intervals, and the length of the feed ball screw 2 and the number of rotations are not limited. Accordingly, a suitable number of bearing brackets may be arranged at appropriate intervals. Other configurations are first
It is similar to the embodiment.

In this movable bearing device, when the movable body 16 moves along the feed ball screw 2, the pantograph 4 moves.
One side of 6 is shortened evenly and the other side is stretched evenly. In FIG. 5, the left side is shortened and the right side is extended.
In this state, the bearing bracket 48 on the left side of the movable body 16 is
a-48c are arranged relatively densely, and the bearing bracket 4 on the right side
8d to 49f are arranged relatively sparsely. Bearing bracket 48d
The bearing brackets up to 49f move in the same direction as the moving body 16 at a speed closer to the speed of the moving body 16 as the bearing bracket is closer to the moving body 16, and are moved so as to be separated from the moving body 16 without fail.
Any number of bearing brackets 48d to 49f can be arranged according to the length of the feed ball screw 2, and the unsupported length of the feed ball screw 2 can be made extremely short.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and various modifications can be made. For example, in the first embodiment, the magnet is the movable body 1
However, the bearing brackets 22a and 22b may be arranged. An electromagnet may be used instead of the permanent magnet. In this case, the attraction force between the moving body 16 and the bearing brackets 22a and 22b is canceled by shutting off the power source, and the bearing brackets 22a and 22b are left at the center of the feed ball screw 2. Therefore, it is possible to eliminate the central stopper 20.

Further, instead of the magnet, a detachable engaging means may be provided between the movable body 16 and the bearing brackets 22a and 22b. Such engaging means may be a combination of elastically deformable hooks and protrusions, and one of them is arranged on the movable body 16 and the other is arranged on the bearing brackets 22a and 22b.

Further, in the second embodiment, the auxiliary feed ball screw 38 is used.
The driving means for driving the gears at half the feed pitch is the gear 40,
In addition to 42, although it is a separate system from the motor 8, it may be a drive means that rotates at a constant rate of the number of rotations of the motor 8.

In each of the embodiments, bearing brackets are provided on both sides of the moving body 16, but the moving body 16 is moved at a high speed only at a specific position of the feed ball screw 2 and is moved at a low speed at other positions. In this case, it is not always necessary to dispose the bearing brackets on both sides of the movable body 16, and it is possible to dispose the bearing brackets on only one side.

Further, although the feed ball screw 2 and the ball nut 32 are used in the above-mentioned embodiment, the moving bearing device of the present invention can be constructed by a combination of a normal feed screw and a nut.

The positioning means for locating the bearing bracket at a position separated from the body to be moved 16 is not limited to those shown in the above-mentioned respective embodiments, and various methods such as a method of connecting the body to be moved 16 with the bearing bracket by a spring. Can be adopted.

[0028]

As described above, according to the present invention, the linear guide is arranged in parallel with the feed screw, the bearing bracket is slidably mounted on the linear guide, and the nut is rotated on the rolling bearing arranged on the bearing bracket. The nut is freely fitted, and the feed screw is inserted into this nut to support the feed screw, and the bearing bracket is positioned by the positioning means at a position separated from the moving body. The unsupported part of the feed screw can be supported by the linear guide through the nut and the bearing bracket without causing any trouble to the guide, thus preventing the bending of the middle part of the feed screw during high speed rotation of the feed screw. The long and thin feed screw makes it possible to move the moving body at a high speed over a long distance.

[Brief description of drawings]

1A and 1B are side views of a mobile bearing device according to a first embodiment of the present invention.

FIG. 2A is a vertical sectional view of a bearing bracket, and FIG. 2B is a sectional view of a linear guide.

FIG. 3 is a side view of the movable bearing device according to the second embodiment of the present invention.

FIG. 4 is a left side view of FIG.

FIG. 5 is a side view of a movable bearing device according to a third embodiment of the invention.

[Explanation of symbols]

 2 Feed ball screw 4,6 Fixed bearing 8 Motor 16 Moving body 18 Linear guide 20 Stopper 22a, 22b Bearing bracket 28 Bearing housing hole 30 Rolling bearing 32 Ball nut 34 Screw hole 36 Permanent magnet 38 Sub feed ball screw 40, 42 Gear 44 fixed bearing bracket 46 pantograph 48a-48f bearing bracket 50, 52 connecting member

Claims (6)

[Claims] 1. A feed screw which is screwed with a moving body to feed the moving body, a linear guide arranged in parallel with the feeding screw, and slidably supported by the linear guide and rolling. A bearing bracket having a bearing, a nut rotatably fitted to the inner circumference of the rolling bearing, and screwed to the outer circumference of the feed screw, and the bearing bracket positioned at a position separated from the movable body. A moving bearing device for a feed screw, comprising: positioning means. 2. A stopper for preventing passage of the bearing bracket is arranged at an intermediate portion of the linear guide, and a pair of the bearing brackets is arranged on both sides of the stopper.
The movable body is disposed between the pair of bearing brackets, and a magnet for attracting the movable body and the bearing bracket to each other is disposed at a position where the movable body and the bearing bracket face each other. A mobile bearing device for the described lead screw. 3. The movable bearing device for a feed screw according to claim 2, wherein instead of the magnet, an engaging means that can be easily separated is provided at a portion where the movable body and the bearing bracket face each other. . 4. A sub-feed screw is arranged in parallel with the feed screw, drive means for driving the sub-feed screw at a feed pitch half the feed pitch of the feed screw is arranged, and the bearing bracket is provided with the above-mentioned bearing bracket. A pair is arranged on both sides of the moving body,
The movable bearing device for a feed screw according to claim 1, wherein the bearing bracket is screwed to the auxiliary feed screw. 5. A pantograph is disposed parallel to the feed screw, and the movable body is connected to an intermediate portion of the pantograph, and at least one bearing bracket spaced from the movable body is connected to the pantograph. Claim 1
A mobile bearing device for the described lead screw. 6. The movable bearing device for a feed screw according to claim 5, wherein the same number of bearing brackets are arranged on both sides of the movable body, and the bearing brackets are connected to the pantograph at predetermined intervals. .