JPH079259B2 - Ball screw soundproofing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ball screw soundproof device for protecting a ball return tube of a ball screw and reducing noise and vibration due to ball rolling.

[Prior Art] As is well known, a ball screw has a spiral groove formed on the inner circumference of a nut and the outer circumference of a shaft inserted into the nut, and a large number of balls are interposed between the spiral grooves. Both ends of the ball rolling portion are communicated with each other through another ball return passage to circulate the ball and relatively rotate the nut and the shaft. Various types of ball returning and circulating means have been conventionally proposed, and in the example shown in FIG.
Ball return tube 2 formed in a U shape from the outer periphery of the
And the ball return tube 2 is fixed to the outer side of the nut 1 with a set screw 4
(Or a tube pressing member that has been pressed). There is also one in which the tube itself is exposed without using the tube pressing member and directly fixed to the nut by caulking. In the example of FIG. 6, two ball return tubes are provided and two ball circulation paths are shown. As still another example, a nut is cut out at a part thereof, and a guide plate made of steel or cast iron having a guide groove for ball returning is attached to this part (for example, the actual Kosho Sho).
No. 47-25419), or the entire outer circumference of the nut including the ball return tube is completely fixed by embedding it with a molding layer of synthetic resin, cast iron, etc., thereby reducing the number of ball circulation component parts, rigidity, or production. In addition, there are those in which the outer shape is formed into an arbitrary shape by using a molding layer (for example, Japanese Patent Publication No. 57-38830).

[Problems to be Solved by the Invention] In the conventional ball screw described above, the ball return tube is partially covered with a metal tube pressing member and fixed, or
Since the ball return tube is exposed and fixed with screws, etc., the sound when the balls collide in the spiral groove or in the tube, and the ball scooping from the spiral groove into the metal tube The sound, vibration, etc. when the ball collides with the part is transmitted to the outside. Such noises and vibrations are easily generated by receiving a moment load due to a mounting error, and particularly when the ball screw speed is increased, a loud noise is generated. In recent years, the use of ball screws has spread, and electronic equipment for office use, medical equipment, or equipment used in a quiet environment such as an automatic drafting machine is a source of unpleasant noise and noise. Even when the ball return path is formed by a guide plate that closes the notch on the nut side instead of the tube, noise and vibration are generated due to the metal contact between the ball and the guide plate.
In addition, because it is a metal (iron) plate, there is no soundproofing or vibration absorption,
Propagate directly from the guide plate to the outside. Even in the case of Japanese Patent Publication No. 57-38830, in which the entire circumference of the nut is fixed with a molding layer of synthetic resin, cast iron, etc., vibration cannot be absorbed and sound cannot be prevented depending on the material of the molding layer. Also, because the nut outer circumference is completely fixed with the molding layer together with the ball return tube, it is difficult to disassemble and repair the tube part and ball rolling part, and the material and thickness of the molding layer can be changed according to the usage conditions of the ball screw. There are various problems such as being unable to do so. If the ball return tube is exposed, there is a risk of hitting or damaging the tube itself.

[Means for Solving the Problems] Therefore, the present invention attaches a tube holding member made of a cushioning material, which is provided on the outer side portion of the ball screw nut, to the outer portion of the ball screw nut, the tube holding member having a groove portion in close contact with the ball return tube. The above problem was solved by wrapping the entire ball return tube. That is, the soundproof device for a ball screw of the present invention has a flat notched surface having a tube insertion hole for ball return on the outer side of the ball screw nut, and the U-shaped ball return tube of the U-shaped ball return tube is formed in the tube insertion hole of the notched surface. A ball circulation path communicating with the spiral groove of the ball screw nut is formed by inserting both ends thereof into and out of the ball screw nut, and has a back surface having substantially the same size as the cutout surface, and the ball return tube is provided on the back surface from the cutout surface. A tube holding member made of cushioning material, in which a groove having a depth slightly smaller than the protruding amount is formed on a substantially diagonal line, is arranged, and the tube holding member is pressed and fixed to the cutout surface with a set screw from the outer surface side of the tube holding member. Then, when the tube pressing member is fixed to the cutout surface, the ball return tube is closely adhered to and surrounded by the groove portion.

[Operation] By doing so, the vibration generated in the ball return tube due to the rolling of the ball can be absorbed by the elasticity of the tube pressing member, and since the ball return tube is isolated from the outside air, the vibration of the ball return tube causes the outside air to vibrate. Can be prevented from being transmitted.

[Embodiment] Next, the present invention will be described with reference to the drawings.

FIG. 1 is a partial perspective view of a ball screw according to an embodiment of the present invention with a shaft portion removed. The ball screw nut 1 is flatly cut out at a part of the outer side thereof, and a ball-returning structure in which a ball is allowed to pass through a tube formed in a U-shape in a substantially diagonal direction on the cutout surface 5. The tube 2 is arranged. Both ends of the ball return tube 2 are inserted into tube insertion holes provided in the cutout surface 5, and the inner hole of the ball return tube communicates with the spiral groove 6 in the ball screw nut 1. Although not shown,
A spiral groove corresponding to the spiral groove 6 of the nut 1 is also formed on the outer peripheral portion of the shaft inserted into the nut 1. Before mounting the tube 2 with the shaft inserted in the nut 1, a large number of balls 7 are packed in the spiral groove and the ball return tube 2 through the tube insertion holes of the cutout surface 5 of the nut 1. , Next, cover the ball with the required number of balls and attach it. By the relative rotational movement of the shaft and the nut 1, the ball 7 is sandwiched between the spiral groove of the shaft and the spiral groove 6 of the nut 1 and rolls along the spiral groove 6, and from one end of the ball rolling portion of the groove. It is picked up into the ball return tube 2 and returns through the tube 2 to the other end of the ball rolling portion of the spiral groove 6 for recirculation. During this ball circulation, the holes 7 intermittently hit the ball return tube 2 and generate a sound. In particular, the tube 2
Noise and vibration are generated at the ball scooping portion 2a at the end of the.
Since this type of tube 2 is usually formed of a thin metal tube, the sound of vibration is transmitted to the surroundings as a resonance sound and a reverberation sound. In the present invention, in order to elastically support and control the ball return tube and to reduce the leakage of the sound generated by the vibration of the ball return tube to the outside, a cushioning material such as a flexible synthetic resin or hard rubber is used. A crescent-shaped tube pressing member 8 which is entirely formed of a sound absorbing material is attached to the cutout surface 5 so as to be in close contact with the tube 2 and to cover the entire tube exposed from the cutout surface 5 with a set screw 4 so as to be detachable. There is.

As shown in FIGS. 2 to 4, the tube pressing member 8 has a bottom surface of a size that exactly matches the notch surface 5 of the outer portion of the nut 1.
The outer surface 8b has a curved surface having the same curvature as the outer portion of the nut 1, and a counterbore 9 is provided for mounting the member 8 on the notched surface 5 of the nut 1. On the bottom surface 8a of the tube pressing member 8, there is provided a groove portion 10 having a U-shaped cross section, which is in close contact with the ball return tube 2 exposed on the nut notch surface 5 and which is sufficient to wrap the tube. Are formed substantially diagonally. In this case, the depth of the groove portion 10 of the tube pressing member is formed to be slightly smaller than the protruding amount of the tube 2 from the cutout surface 5 of the nut 1. When the notched surface 5 of the nut 1 is closed with the half-moon shaped tube pressing member 8 and tightened with the setscrew 4, the ball return tube 2 is brought into close contact with the bottom of the groove portion 10 of the bottom surface 8a so that the tube 2 is elastic. The tube 2 is securely fixed by pressing the tube 2 against the inside of the tube 2, and at the same time, the sound and vibration transmitted from the tube 2 to the outside are generated by the member 8
The vibration absorption principle by the elasticity of works to absorb and reduce noise and vibration.

FIG. 5 (a) shows a sound amplitude waveform of a conventional ball screw in which a ball return tube is pressed by an iron guide plate.
FIG. 5 (b) is a diagram showing the amplitude waveform of the sound produced by the ball screw using the hard rubber tube pressing member of the present invention, and FIG. ) Is an example of an experimental example showing that there is no acoustic problem. Both were detected by a microphone at a position 40 cm away from the ball screw. 5KH _Z if: the sound frequency with the case of the above 50KH _Z Fuhaba is understood that the direction of the present invention is reduced to about 1/2. According to various experiments, the soundproof effect varies depending on the operating conditions (rotational speed, axial load, etc.) of the ball screw even if the material of the cushioning material of the tube pressing member is the same. Therefore, it is necessary to select and use a material having the best effect for various operating conditions.However, in the present invention, since the tube pressing member has a structure that is fixed to the nut by snapping,
It is possible to easily change to another cushioning material according to the conditions at that time.

[Effects of the Invention] As described above, according to the present invention, by covering the ball return tube exposed from the nut with the tube holding member which is entirely formed of the elastic cushioning soundproof material, the sound generated during the operation of the ball screw, There is an effect that vibration can be reduced, and damage or the like due to the ball return tube accidentally colliding with another member can be prevented. A groove for pressing the ball return tube is formed smaller than the tube in the tube pressing member, and the tube is strongly pressed and fixed by the compressive deformation of the groove. Yes, the tube will not slip or loosen to the removal side during use or handling. Since the tube holding member can be attached to and detached from the nut by the set screw, it does not hinder the disassembly and repair of the ball screw, and it is possible to select and use a member made of an appropriate material each time according to the operating conditions. Bring about the effect of.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a ball screw according to an embodiment of the present invention with a shaft body removed, FIG. 2 is an enlarged bottom view of a tube pressing member applied to the present invention, and FIG. 2 is a sectional view taken along line III-III in FIG. 2, and FIG. 4 is IV in FIG.
5A and 5B are sectional views taken along line -IV, showing the sound amplitude generated by the ball screw in comparison between the conventional structure and the present invention, and FIG. 6 shows the conventional ball. It is a perspective view which cut a part as an example of a screw structure. 1 ... Nut, 2 ... Ball return tube, 3,8 ... Tube pressing member, 5 ... Notched surface, 6 ... Spiral groove, 7 ... Ball, 9 ... Counterbore hole, 10 ... Groove section.

Claims (2)

[Claims] 1. A flat notched surface having a tube insertion hole for ball return is formed on the outer side of a ball screw nut.
Both ends of a U-shaped ball return tube are removably inserted into the tube insertion holes of the cutout surface to form a ball circulation path communicating with the spiral groove of the ball screw nut, and a back surface having substantially the same size as the cutout surface. And a cushioning tube holding member made of a cushioning material, which has a groove portion having a depth slightly smaller than the amount by which the ball return tube projects from the cutout surface, is formed on the back surface of the tube holding member. Characterized in that the tube pressing member is pressed and fixed to the cutout surface with a set screw, and when the tube pressing member is fixed to the cutout surface, the ball return tube is closely adhered to and surrounded by the groove portion. Soundproofing device for screws. 2. The tube holding member made of cushioning material is formed of a hard rubber material such as nitrile rubber and is detachably attached to the notched surface of the ball screw nut. Soundproofing device for the described ball screw.