JPS60227054A - Ball screw device - Google Patents

Abstract

PURPOSE:To effectively use a ball screw device for quick-feed means of a moving mechanism by providing the ball screw device with a pair of half nuts, ball retaining means having linear retaining portion, a ball circulating member, and a relief groove formed on the bottom of a valley of a screw groove. CONSTITUTION:A ball screw device 1 comprising a screw shaft 2, a nut 3 and a screw groove 4 is provided with a pair of half nuts 3a, 3b formed by axially dividing the nut 3, ball retaining means 9 having a plurality of retaining portions 10 for retaining balls 6 in screw grooves of the half nuts, a ball circulating member 7 with a plurality of circulation paths for the balls 6. In this arrangement, when the half nuts engaged with the screw shaft are radially opened and closed, and attached and detached, the balls are kept from slipping off. Therefore, the bal screw device can be effectively used for quick-feed means of a moving mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ball screw device used in a table moving mechanism of a measuring device, and more particularly to a ball screw device in which a pair of half-split nuts are screwed onto a screw shaft via balls. Related to equipment.

BACKGROUND ART In general measuring devices, a mechanism that uses a half-split nut in a feed screw device to switch the feed between automatic and manual has been known for a long time. 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 in the radial direction and released from the screwed state. It looks like this.

When a ball screw device is used as the feed screw device and a half nut system is used, the balls fall out of the screw groove when the half nut is opened in the radial direction and released from the screwed state. Therefore, although it is necessary to prevent the balls from falling off in the half-nut system of ball screw electrical manufacturing, it is difficult to find a means for holding the balls.

Furthermore, if the conventional ball screw snow making system is not a half-split nut system, for example, when it is desired to automatically feed the table from an arbitrary position, it is necessary to move the table to that arbitrary position. In such cases, even when a speed-changed automatic rapid-forwarding means is used, there is a drawback that workability is poor, so the appearance of a practical half-nut type ball screw device has been long awaited.

The present invention was developed to solve the above-mentioned drawbacks, and includes a screw shaft having a thread groove, a plurality of balls that roll in the thread groove, and a nut that is screwed onto the screw shaft through the balls. A ball screw device consisting of a pair of half-split nuts formed by being divided in the axial direction, and a ball holder having a plurality of linear holding parts for holding balls in threaded grooves of the half-split nuts. By having a ball circulation member with multiple ball circulation paths and a relief hole formed at the bottom of the thread of the screw shaft, it is possible to open and close the half-split nut screwed onto the screw shaft in the radial direction. To provide a ball screw device which does not cause balls to fall off even when attached and detached, has a simple structure, and is useful as a fast-forwarding means of a moving mechanism.

Embodiments of the ball screw device of the present invention will be described below with reference to the drawings.

In FIG. 1, ``■'' is a ball screw device, and the ball screw device 1 has a screw shaft 2 and a nut 3, and a screw groove 4 is formed on the outer peripheral surface of the screw shaft 2. The nut 3 is a pair of halves that are twisted in half on the axial surface of the nut 3) 3a
, 3b are formed. A threaded groove 5 is provided on the inner peripheral surface of each half-split nuts) 3a, 3b, and a plurality of balls are provided between the threaded groove 4 of the screw shaft 2 and the threaded groove 5 of the half-split nuts) 3a, 3b. 6, allowing for transfer.

Reference numeral 7 denotes a ball circulation member provided in each of the half-split oaks 3a and 3b, and the ball circulation member 7 has a plurality of circulation paths 8 formed on its outer circumferential surface so that the balls 6 can be circulated therein.

Each half-split oak) 3a and 3b has a ball holder 9 added to the split surface side, as shown in FIG. The ball holder 9 has two linear holding parts lO, and the linear holding part 10 is arc-shaped as shown in FIG.
The ball 6 rolling on the surface is held by the half-split oak 3a. The half-split nut 3a has a recess 11 in the center.
A ball circulation member 7 having an arcuate surface is fitted into this recess 11, and the ball circulation member 7 is fixed to the half-split oak 3a by a ball holder 9. A circulation path 8 provided in the ball circulation member 7 is connected to a threaded groove 6 of the half-split nut, and is formed so that the balls 6 can be circulated through the cylinder.

As shown in FIG. 4, the screw @2 has an escape groove 12 formed at the bottom of the thread groove 4 of the screw shaft. Escape groove 1
2 is formed so that when the ball 6 is held (half-split oak) 3a, 3b is screwed onto the screw shaft 2, the hook-shaped holding part 10 of the ball holder 9 does not touch the rod. The cross-sectional shape of the linear holding 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 threaded groove 5 of the halved nut.

In the ball screw device configured as described above, since the nut 3 is formed of a pair of half-split nuts 3a and 3b,
Each half-split oak) 3a, 3b can be opened and closed by moving them in the radial direction. Halved nuts 3a, 3b
When it is screwed into the screw shaft 2, it becomes a trap as shown in Fig. 4, and when it is moved radially from the screw shaft 2 and opened, it becomes a trap as shown in Fig. 5, and the ball 6 is in the ball holding part. linear holding part 1
It is held at 0 (half-split oak) to prevent it from falling off from 3a and 3b. In addition, it is half-split for screw shaft 2)
When the screw shaft is rotated with 3a and 3b closed and screwed together, the balls 6 roll on the 4.5 sides of each screw groove of the screw shaft 2 and the half-split nuts 3a and 3b, and the balls 6 roll into the ball circulation member 7. It is configured to circulate within a provided circulation path 8.

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

As mentioned above, the ball screw device of the present invention includes a screw shaft having a threaded groove, a plurality of balls that roll in the threaded groove, and a nut that is screwed onto the screw shaft through the balls. , a pair of half-split nuts formed by being divided in the axial direction, and q4) a ball holder having a plurality of 'linear holding parts for holding balls in threaded grooves of the half-split nuts; By having a ball circulation member with multiple circulation paths and a relief groove formed at the bottom of the thread groove of the screw shaft, it is possible to open/close/remove the half-split nut screwed onto the screw shaft in the radial direction. The ball does not fall off even when the ball is moved, the structure is simple, the cost is low, and it can be effectively used as a fast-forwarding means for a moving mechanism such as a positioning device of a measuring machine.

[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 half-split nut taken along line A in the direction of the arrow; FIG. 3 is a sectional view taken along line B-B in FIG. 2; FIG. FIG. 2 is an enlarged cross-sectional view of a main part for explaining when the screwed state is released. Explanation of symbols ■... Ball screw device 2... Screw shaft 3... Nuts 3a, 3b...
Half nut 4.5... Thread groove 6...
... Ball 7 ... Ball circulation member 8 ... Circulation path 9 ... Ball holder 10 ... Linear holding part 12 ...・Let's run away. Patent applicant NSK Ltd. Figure 2

Claims (1)

[Claims] (1) In a ball screw device consisting of a screw shaft having a threaded groove, a plurality of balls that roll in the threaded groove, and a nut that is threadedly engaged with the door-to-door shaft via the balls, the nut is screwed into the shaft. A ball holder having a pair of half-split nuts formed by being divided in the direction, a plurality of linear holding parts for holding the balls in threaded grooves of the half-split nuts, and a circulation path for the balls. A ball screw device comprising: a plurality of ball circulation members; and an escape groove formed at the bottom of the thread groove of the screw shaft.