JPS6333002Y2 - - 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.

[Conventional technology]

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 traction feeding when the half-split nut is opened in the radial direction and released from the screwed state. It's becoming like that.
In particular, when a ball screw device is used as the feed screw device and a half-nut system is used, a means is required to hold the steel balls rolling on the screw shaft and the threaded groove surface of the nut.

[Problem that the invention attempts to solve]

Generally, in half-nut type feed screw devices, when closing the half-nut and switching to automatic feed,
Half nuts are often closed with the male and female screws misaligned. In particular, if there is a 1/2 pitch misalignment between the male and female screws, the male and female screws will no longer engage, so it is necessary to move one of the male and female screws relatively to the position where they will engage, which will reduce work efficiency. It has the disadvantage of being bad.

In addition, in the case of a half-nut-type ball screw device, when the half-nut is closed, the holder holding the steel ball to the half-nut may become attached to the screw shaft due to the pitch misalignment of the male and female screw grooves. Since it comes into contact with
There was a drawback that the holder was easily damaged.

[Means for solving the problem]

The ball screw device of the present invention includes a screw shaft having a male thread groove, a plurality of steel balls rolling in the thread groove,
In a ball screw device comprising a nut having a female thread groove that is screwed into the male thread groove through the steel ball, at least one pair has a circulation path for the steel balls and is divided in the axial direction. A half-split nut, a retainer fixed to the half-split nut holding a steel ball in a female thread groove, an escape groove provided at the bottom of the male thread groove, and a female thread groove in which the steel ball rolls are separated by at least one pitch. The problem was solved by providing a guide pin fixed to at least one location on the inner surface of the half-split nut at a pitch interval between the two, and a land portion formed with a convex curved surface in the axial direction of the screw shaft.

〔Example〕

In FIG. 1, a ball screw device 1 includes 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, and a female thread groove 5 is formed on the inner surface of the nut 3. and female thread groove 5
A plurality of steel balls 6 are fitted between them. The nut 3 is formed of a pair of half nuts 3a and 3b that are divided into two in the axial direction.

Each half nut 3a, 3b is shown in Fig. 2 and 3.
As shown in the figure, a plurality of steel balls 6 are held in the female thread groove 5 by a holder 7 so as to be rotatable. The holder 7 has an arc-shaped linear part 8 in the center, and the linear part 8 holds six steel balls, and both ends of the holder 7 are screwed into half nuts 3a, 3b by machine screws 9.
It is fixedly installed. A circulation path 10 for circulating the steel balls 6 is formed in each half nut 3a, 3b, and both ends of the circulation path 10 communicate with the female thread groove 5. 3 halved nuts each
a, 3b are formed from a central member 11 having a female thread groove 5 and side members 12 fixedly provided on both sides of the central member 11. Four guide pins 13 are fixed to each half nut 3a, 3b on both sides of the female thread groove 5 in the axial direction in which the steel ball 6 rolls. The guide pin 13 is located at a position close to the dividing surface 14 of the half-split nuts 3a, 3b, and at a position one pitch away from the female thread groove 5 in the axial direction from the female thread groove 5 in which the steel ball 6 rolls.
The guide pin 13 is attached so that its axis is in the centripetal direction of the female thread groove 5.

As shown in Fig. 4, the screw shaft 2 has a male thread groove 4.
A relief groove 15 is formed at the bottom of the groove, and a land portion 16 corresponding to the outer surface of the screw shaft 2 between adjacent male thread grooves 4 is a convex curved surface such that the axial cross-sectional shape of the screw shaft 2 is an arc surface. It is formed. Guide pin 1
The tip 17 of the guide pin 3 has a spherical shape, and when the tip 17 of the guide pin comes into contact with the male thread groove 4 surface and the land, the linear portion 8 of the holder and the linear portion 8
A guide pin 13 is formed so that the steel ball 6 held by the steel ball 6 does not come into contact with the male thread groove 4 surface or the land portion 16. When the male thread groove 4 and the female thread groove 5 are screwed together via the steel ball 6, the linear portion 8 of the holder and the tip 17 of the guide pin fit into the relief groove 15, and the surface of the relief groove 15 It is designed so that it does not come into contact with the

The guide pin 13 is not limited to that described in the above embodiment, but may be of the following type.

The number of guide pins 13 is one pair of half nuts 3a,
At least one is sufficient for 3b, and it is preferable to provide a plurality of them in consideration of stability or safety against processing errors or assembly errors. Also, guide pin 1
3 is not limited to the position one pitch away from the female thread groove in which the steel ball 6 rolls,
The positions may be separated by an integral multiple of the pitch interval of the female thread groove. Furthermore, the fixed position of the guide pin 13 is not limited to a position close to the dividing surface 14 of the half-split nut, but may be a position away from the dividing surface within a range that does not affect the operation of the present invention, or a position close to the dividing surface 14 of the halved nut. Nut 3a,
It may be attached to the axial side surface of 3b. Furthermore, the tip 17 of the guide pin 13 is not spherical;
It may have a shape similar to the thread of a nut, and may have a shape that increases the length of contact when it comes into contact with the six surfaces of the male thread groove of the screw shaft.

[Effect]

As mentioned above, in the ball screw device of the present invention, the nut 3 is formed of a pair of half-split nuts 3a, 3b, so each half-split nut 3a, 3b can be moved in the radial direction to open and close. .
When the half nuts 3a, 3b are closed, the male thread groove 4 and the female thread groove 5 are screwed together via the steel ball 6, and the steel ball 6 connects the circulation path 10 formed in the half nut 3a, 3b. Circulation enables automatic feeding. When the half nuts 3a, 3b are opened and a relative displacement in the axial direction is manually applied between the half nuts 3a, 3b and the screw shaft 2, then the half nuts 3a, 3b are closed. Half-split nuts 3
Even if the pitch of the threaded groove is misaligned between a, 3b and the screw shaft 2, the tip 17 of the guide pin will first come into contact with the female thread groove 4 surface or the land portion 16 of the screw shaft, and then the guide pin will The tip portion 17 is guided to the relief groove 15 while sliding on the contact surface, and the pitch deviation is corrected.

[Effect of idea]

When the ball screw device of the present invention closes a half-split nut divided in the axial direction and switches to automatic feeding, even if there is pitch misalignment between the male and female screws, the guide pin corrects the pitch misalignment. Even if there is a 1/2 pitch misalignment, the male and female screw grooves can be well engaged by forming the land part formed into a convex curved surface and the tip part of the guide pin into a spherical shape. This also improves workability. In addition, when closing the half-split nut, even if the male and female thread grooves are misaligned, the tip of the guide pin will not come into contact with the male thread groove surface or the land and the holder will be damaged. It has the effect of not having any problems.

[Brief explanation of the drawing]

The drawings show an embodiment of the ball screw device of the present invention, and FIG. 1 is a front view of the ball screw device partially shown in cross section, and FIG. 2 is an arrow taken along line A-A in FIG. 1. 3 is a side view showing a partial cross section along the line B-B in FIG. 2, and FIG. 4 is an enlarged cross-section of the main part taken along the line C-C in FIG. 3. It is a diagram. 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...
...Steel ball, 7...Holder, 10...Circulation path, 13...
...Guide pin, 15...Escape, 16...Land section.

Claims (1)

[Scope of utility model registration request] A ball screw device comprising a screw shaft having a male thread groove, a plurality of steel balls rolling in the male thread groove, and a nut having a female thread groove that is screwed into the male thread groove via the steel balls. at least one pair of half-split nuts each having a ball circulation path and formed by being divided in the axial direction of the nut; and the steel ball is held in the female thread groove and fixed to the half-split nut. an escape groove provided at the bottom of the male threaded groove, and a relief groove provided at the bottom of the female threaded groove in the axial direction from the female threaded groove in which the steel ball rolls.
a guide pin fixed to at least one location on the inner surface of the half-split nut at a pitch interval or more apart, and a land portion formed with a convex curved surface in the axial direction of the screw shaft; A ball screw device that is characterized by correcting bit misalignment when screwing into a groove.