JPH0480262B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a ball screw device used in a table moving mechanism of a measuring device, etc., and in particular, a ball screw device in which a pair of half-split nuts are screwed onto a screw shaft through balls. This relates to a ball screw device that has been fitted with a ball screw device.

[Prior Art] A mechanism has been known for a long time in general measuring equipment, etc., in which the feed can be switched between automatic and manual by using a half-split nut in the feed screw device when the ball screw is not in use. . In other words, this type of feed screw device performs automatic feeding when the half-split nut is closed and screwed onto the screw shaft, and can perform manual feeding when the half-split nut is opened radially and released from the screwed state. It's becoming like that.

Additionally, in general, in a table moving mechanism using a ball screw device, for example, when attempting to start automatic feeding of the table from an arbitrary position, a means is required to quickly move the table to that arbitrary position. By adding a conversion mechanism to the ball screw device,
Devices that can rapidly move to a desired position have also been used.

[Problems to be Solved by the Invention] When using a half-split nut method in a conventional ball screw device, when the half-split nut is opened in the radial direction and released from the screwed state, the screw shaft and the nut face each other. Since the balls rolling on the threaded groove surface would fall off, a means to hold the balls against the nut was required. However, it was difficult to realize such a holding means for preventing balls from falling off.

In addition, when adding a conversion mechanism to a conventional ball screw device, even if you use rapid traverse to move the table to a desired position, it lacks speed and workability is poor, and it is difficult to use a speed change mechanism. There were drawbacks such as the equipment being expensive.

[Means for Solving the Problems] In order to solve the problems of conventional ball screw devices, the present invention provides a screw shaft having a male thread groove, a plurality of balls that roll on the male thread grooves, and a screw shaft that rotates through the balls. A ball screw device comprising a nut having a female thread groove that is screwed into a screw shaft, and a pair of half-split nuts formed by dividing the nut in the axial direction;
A ball circulation member that communicates with both ends of the female thread groove in which the balls roll and has a plurality of independent circulation paths for circulating the balls, and a halved nut that holds the balls in the female thread groove of each half nut. The structure includes a ball holder having a plurality of arc-shaped linear parts fixedly attached to the ball holder, and an relief groove formed at the bottom of the female screw groove.

[Function] In the ball screw device of the present invention, since the nut is formed of a pair of half nuts, each half nut can be opened and closed by moving in the radial direction. When the half nut is closed, the male thread groove and the female thread groove are screwed together through the balls, and when the half nut is moved radially from the screw shaft and opened, the balls are held by the linear part of the ball holder. It is designed to prevent it from falling off the half-split nut.

By adopting the half-split nut system to prevent the balls from falling off, it became possible to quickly move the table manually without adding an expensive conversion mechanism.

[Example] In FIG. 1, 1 is a ball screw device, and the ball screw device 1 has a screw shaft 2 and a nut 3.
A male thread groove 4 is formed on the outer peripheral surface of the screw shaft 2. The nut 3 is formed of a pair of half-split nuts 3a and 3b that are divided into two in the axial direction of the nut 3.

A female thread groove 5 is formed on the inner peripheral surface of each half nut 3a, 3b, and a plurality of balls 6 are formed between the male thread groove 4 of the screw shaft 2 and the female thread groove 5 of the half nut 3a, 3b. It is designed so that it can be rolled. Reference numeral 7 denotes a ball circulation member provided on each half nut 3a, 3b, and the ball circulation member 7 has a plurality of circulation passages 8 formed on its outer peripheral surface so that the balls 6 can circulate therein.

As shown in FIG. 2, each half-split nut 3a, 3b has a ball holder 9 attached to the split surface side.
The ball holder 9 has two linear parts 10, each of which has an arc shape as shown in FIG. It is designed to be held by a nut 3a. A recess 11 is provided in the center of the half-split nut 3a,
A ball circulation member 7 having an arcuate surface is fitted into this recess 11, and the ball circulation member 7 is attached to the half-split nut 3a by a ball circulation member support portion 13 provided on the ball holder 9.
is supported by The circulation path 8 provided in the ball circulation member 7 is connected to the ball circulation member support part 1 in the ball support 9.
Ball guide portion 14 formed between 3 and the linear portion 10
It communicates with the female screw groove 5 of the half-split nut through a passageway, and is formed so that the balls 6 can circulate smoothly.

As shown in FIG. 4, the screw shaft 2 has an escape groove 12 formed at the bottom of the male thread groove 4 of the screw shaft. The escape groove 12 is formed so that the linear portion 10 of the ball holder 9 does not abut when the half nuts 3a, 3b holding the balls 6 are screwed onto the screw shaft 2. The cross-sectional shape of the linear portion 10 is not limited to a rectangular shape, but may be circular or any other shape as long as the ball 6 can be held in the female screw groove 5 of the half-split nut.

The ball circulation member is not limited to the embodiment, and a return tube, which is a well-known ball circulation means in a conventional ball screw device, may be used.

[Effects of the Invention] The ball screw device of the present invention includes a screw shaft having a male thread groove, a plurality of balls rolling in the male thread groove,
A nut with a female thread groove that is screwed onto a screw shaft through the ball, and a pair of half-split nuts formed by dividing the nut in the axial direction, and the ball rolls. A ball circulation member that communicates with both ends of the female thread groove and independently provides a plurality of circulation paths for circulating the balls, and a plurality of arc-shaped linear parts that hold the balls in the female thread groove of each half nut. A ball holder consisting of a ball guide part and a ball circulation member support part forming a part of the circulation path, and an escape groove formed at the bottom of the female thread groove make it easy to thread the screw shaft. The ball does not fall off even when the mating half-split nut is opened/closed/detached in the radial direction, has a simple structure, is inexpensive, and can be used as a fast-forwarding means for moving mechanisms such as positioning devices for measuring instruments. The effect of this can be obtained.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the ball screw device of the present invention, in which FIG. 1 is a front view of the main part partially shown in cross section, and FIG. A plan view of the halved nut seen in the direction of the arrow on line A,
Figure 3 is a sectional view taken along line B-B in Figure 2;
The figure is an enlarged cross-sectional view of the main part to explain the screwed state, and FIG. 5 is an enlarged cross-sectional view of the main part to explain the state when the screwed state is released. Explanation of symbols, 1...Ball screw device, 2...Screw shaft, 3...Nut, 3a, 3b...Half nut, 4...Male thread groove, 5...Female thread groove, 6...
...Ball, 7...Ball circulation member, 8...Circulation path, 9...
Ball holder, 10... linear part, 12... escape groove.

Claims (1)

[Claims] 1. In a ball screw device comprising a screw shaft having a male thread groove, a plurality of balls rolling in the male thread groove, and a nut having a female thread groove that is screwed into the screw shaft via the balls, the nut is A pair of half-split nuts formed by being divided in the axial direction are connected to both ends of the female thread groove in which the balls roll, and a plurality of circulation paths for circulating the balls are provided, respectively. a ball circulation member, a ball holder having a plurality of arc-shaped linear portions that hold the balls in the female thread groove of each half nut and are fixed to the half nut; and a bottom of the female thread groove. A ball screw device characterized by having an escape groove formed in the.