JP2005249046A - Ball screw device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide low-noise medical instruments and office supplies by smoothly circulating a rolling element to reduce noise due to passing of the rolling element. <P>SOLUTION: This ball screw device 10 built in the medical instrument or office supplies includes a circulating part 17, both end parts of which are fitted to a set of two circulating holes 20 to internally form a rolling element circulating passage for guiding the rolling element 15 rolling in a load area between both screw grooves 11, 13 from one circulating hole 20 of the circulating holes 20 provided in the side of a nut 14 to the outside of the nut 14, and returning the same from the other circulating hole 20 to the load area. The direction of scooping up the rolling element 15 by the circulating part 17 is a tangential direction of a screw shaft 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ball screw device incorporated in medical equipment or office equipment.

As a conventional ball screw device of this type, for example, the one shown in FIG. 2 is known.
In this ball screw device 1, a nut 6 having a helical thread groove 4 corresponding to the screw groove 2 is screwed onto a screw shaft 3 having a helical thread groove 2 on the outer peripheral surface.
The screw groove 4 of the nut 6 and the screw groove 2 of the screw shaft 3 are opposed to each other to form a spiral load region between them, and a large number of balls 5 as rolling elements are rolled in the load region. It is loaded movably. The nut 6 (or the screw shaft 3) is moved in the axial direction through the rolling of the ball 5 by the rotation of the screw shaft 3 (or the nut 6).

  Further, a part of the side surface of the nut 6 is a flat surface, and a set of two circulation holes 7 communicating between the screw grooves 2 and 4 are formed on the flat surface so as to straddle the screw shaft 3. By fitting both ends of a tube-shaped circulation component 8 having a substantially U-shape into a set of circulation holes 7, the ball 5 revolving along the load region between the screw grooves 2, 4 is placed in one circulation hole 7. A ball circulation path is formed which is scooped up and led out of the nut 6 and returned from the other circulation hole 7 to the load region.

  However, in the above conventional ball screw device, as shown in FIG. 3, the angle 5 of the ball 5 from the both screw grooves 2 and 4 to the circulating component 8 is θ> 0, and both screw grooves 2 and 4 are formed. Since the rolling ball 5 collides with the tongue of the circulating component 8 and is scooped up into the circulating component 8, vibration noise is generated by the collision of the ball 5, the usage environment is relatively quiet, and noise is a concern. If it is built into a medical device (such as a device that moves with a person such as a bed) or an office device, vibration noise may be transmitted to the human body and cause discomfort to the human body.

In addition, motors are the mainstream for driving ball screw devices. For example, stepping motors cause out-of-step (a phenomenon that causes vibrations when the motor cannot rotate) when a sudden change occurs in the drive torque. In addition, the servo motor adjusts the motor responsiveness called the surf gain in a timely manner according to the load conditions to be used, but when a sudden change in the drive torque occurs Since vibration sounds are generated, there is a problem that these vibration sounds are transmitted to the human body as noise and give an unpleasant feeling to humans.
The present invention has been made to eliminate such inconveniences, and by providing a smooth circulation of the rolling elements, the noise associated with the passage of the rolling elements is reduced, thereby providing a low-noise medical device or office device. It is an object to provide a ball screw device that can be made possible.

In order to achieve the above object, the invention according to claim 1 has a screw shaft having a spiral thread groove on the outer peripheral surface and a spiral screw groove corresponding to the screw groove of the screw shaft on the inner peripheral surface. A nut that is screwed onto the screw shaft, a number of rolling elements that are slidably loaded in a load region between the two screw grooves, and a side surface of the nut that rolls the rolling element that rolls in the load region. Each of the circulation holes is formed so as to form a rolling element circulation path that leads to the outside of the nut from one circulation hole of the set of two circulation holes provided in the outside and returns to the load region from the other circulation hole. A ball screw device built in a medical device or office device,
The scooping-up direction of the rolling element by the circulating component is a tangential direction of the screw shaft.
The invention according to claim 2 is characterized in that the ball screw device according to claim 1 is incorporated.
The invention according to claim 3 is characterized in that the ball screw device according to claim 1 is incorporated.

  According to the present invention, since the rolling-up direction of the rolling element by the circulating part is the tangential direction of the screw shaft, the rolling element smoothly circulates without colliding with the tongue part of the circulating part, and noise accompanying the passage of the rolling element is generated. Accordingly, it is possible to provide a low-noise medical device or office device.

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a ball screw device 10 according to an embodiment of the first aspect of the present invention has a screw shaft 12 having a helical thread groove 11 on an outer peripheral surface and a screw groove 11 on an inner peripheral surface. A nut 14 having a corresponding spiral thread groove 13 is fitted, and the thread groove 13 of the nut 14 and the thread groove 11 of the screw shaft 12 face each other to form a spiral load region therebetween. doing.
A large number of balls 15 as rolling elements are loaded in the load region so as to be able to roll, and the nut 14 (or screw shaft 12) rolls the ball 15 by rotation of the screw shaft 12 (or nut 14). It moves in the axial direction.

A flat surface is formed on a part of the side surface of the nut 14, and a substantially U-shaped tube is formed on the flat surface by, for example, joining members divided into two along the axial direction to each other at the divided surface. A circular circulation component 17 is attached.
The circulation component 17 includes a main body 17a and a pair of leg portions 19 provided on the lower surface side of the main body 17a and extending in a direction substantially perpendicular to the axial direction of the screw shaft 12. The pair of leg portions 19 includes The screw shafts 12 are spaced apart from each other in the axial direction of the screw shaft 12 and are spaced apart from each other in the radial direction of the screw shaft 12. These leg portions 19 communicate with the load region between the screw grooves 11 and 13 and are fitted into a set of two circulation holes 20 drilled in the flat surface of the nut 14.

Further, the interior of each leg 19 of the circulating component 17 is a ball scooping (or ball return) passage 21 of the screw shaft 12, and the interior of the main body 17 a is a ball passage 22 connecting the ball scooping passages 21. Yes.
The ball scooping passage 21 and the ball passage 22 cause the ball 15 that rolls in the load region between the screw grooves 11 and 13 to move from one circulation hole 20 of the pair of circulation holes 20 to each other. A ball circulation path that is scooped up and guided to the outside of the nut 14 and returned from the other circulation hole 20 to the load region is formed in the circulation component 17.

  Here, in this embodiment, the scooping direction of the ball 15 by the circulating component 17, that is, the axis of the ball scooping passage 21 is the tangential direction of the screw shaft 12, and the scooping angle θ of the ball 15 is 0 °. Thereby, the ball 15 circulates without colliding with the tongue portion of the circulating component 17, and noise accompanying the passage of the ball 15 can be reduced.

As described above, in this embodiment, since the ball 15 smoothly circulates without colliding with the tongue portion of the circulation component 17, it is possible to reduce noise accompanying the passage of the ball 15. Even when a stepping motor or a servo motor is used as a drive source, it is possible to provide a low-noise medical device or office device.
The configuration of the screw shaft, nut, rolling element, circulation hole, rolling element circulation path, circulation component, etc. of the ball screw device of the present invention is not limited to the above embodiment, and does not depart from the gist of the present invention. The range can be changed as appropriate.

It is explanatory drawing for demonstrating the ball screw apparatus which is an example of embodiment of this invention. It is sectional drawing for demonstrating the conventional ball screw apparatus. It is explanatory drawing for demonstrating the scooping-up direction of the ball | bowl of the conventional ball screw apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ball screw apparatus 11 Screw groove 12 Screw shaft 13 Screw groove 14 Nut 15 Ball 17 Circulation component 20 Circulation hole 21 Ball scooping path

Claims (3)

A screw shaft having a spiral thread groove on the outer peripheral surface, a nut having a spiral thread groove corresponding to the screw groove of the screw shaft on the inner peripheral surface and screwed onto the screw shaft, and the both screws A large number of rolling elements loaded in a load area between the grooves so as to be able to roll, and the rolling elements that roll in the load area are arranged in one of a pair of circulation holes provided on the side surface of the nut. A circulating part having both ends fitted to each circulation hole so as to internally form a rolling element circulation path that leads from the circulation hole to the outside of the nut and returns to the load region from the other circulation hole; Or in a ball screw device built in office equipment,
The ball screw device characterized in that the rolling-up direction of the rolling element by the circulating component is a tangential direction of the screw shaft.   A medical device comprising the ball screw device according to claim 1.   An office machine comprising the ball screw device according to claim 1 incorporated therein.

Images