JPH074420A - Screw - Google Patents

Abstract

PURPOSE:To provide a screw which can prevent from being loosened or causing bachlash without using parts such as washers and the like. CONSTITUTION:A groove 12 is formed at the apex section of the ridge 11a of a bolt 10, however, no groove 12 is formed at the ridge 11b for several turns from the tip end 10a of the bolt 10, and the thickness of the ridge 11b shall be a standard value as determined in response to the pitch and the diameter of a bolt screw. In this case, the thickness of the ridge 11a for the portion having the groove 12 is set larger than the aforesaid standard value. The width of the screw groove 14 of a nut 13 shall be a standard value as mentioned above, and the thickness of the ridge 11a is made larger than the width of the screw groove 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw used in a combination of a male screw and a female screw.

[0002]

2. Description of the Related Art In a fastening mechanism and a feed mechanism using screws,
Various measures have been taken in order to prevent loosening and rattling of a screw due to a dimensional difference between a thread ridge of a male screw and a thread groove of a female screw. FIG. 5 shows an example of preventing loosening of the fastening mechanism by screws, in which a flat washer 3 and a spring washer 4 are interposed between the bolt 1 and the nut 2 and the pair of plates P. When stronger locking is required, a so-called double nut system in which the nut 2 is tightened and then a lock nut (not shown) is further tightened may be employed. FIG. 6 shows an example of a feed screw mechanism of a machine tool. In this example, the nut body 7 and the adjusting nut 8 are screwed onto the feed screw 6 that drives the driving body 5 such as a table, and the nut body 7 is fixed to the driving body 5, while the adjusting nut 8 and the nut body 7 Is tightened in the axial direction with the adjusting bolt 9 to remove the backlash.

[0003]

In the above-mentioned mechanism, since the flat washer 2, the spring washer 3, and the extra parts such as the adjusting nut 8 and the adjusting bolt 9 are used,
Workability when attaching and detaching screws is reduced. In addition, an increase in weight due to the addition of washers cannot be ignored depending on the number of screws used.

An object of the present invention is to provide a screw which can prevent loosening and rattling without adding a washer or other parts.

[0005]

In the present invention, the thickness of the thread 11a is made larger than the width of the thread groove 14 screwed with the thread 11a. The groove 12 extending along the thread 11a was formed on the top of the thread 11a.

[0006]

When the thread 11a and the thread groove 14 are screwed together, the groove 12 formed at the top of the thread 11a contracts,
Both sides of the thread 11a are pressed against the thread groove 14 by the restoring force.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for making the present invention easy to understand. It is not limited to.

[0008]

Embodiments of the present invention will be described below with reference to FIGS. The same parts as those in FIGS. 5 and 6 described above are designated by the same reference numerals and the description thereof will be omitted. FIG. 1 shows a first embodiment of the present invention. In this example, bolt 10
A groove 12 extending along the thread 11a is formed on the top of the thread 11a. The groove 12 is not formed in the screw thread 11b several turns from the tip 10a of the bolt 10, and the thickness of the thread 11b in this range (the thickness on the axial cross section; the same applies hereinafter) is the pitch of the screw or The value is set according to a standard defined according to the diameter, for example, the Japanese Industrial Standard. on the other hand,
The thickness of the thread 11a in the portion having the groove 12 is set to be larger than the above-mentioned standard. The width of the thread groove 14 of the nut 13 (referred to as the width in the axial direction cross section; the same applies hereinafter) is in accordance with the above-described standard, whereby the thickness of the screw thread 11a becomes larger than the width of the thread groove 14.

In this embodiment, the bolt 10 and the nut 13 are
When the and are screwed together, the groove 12 of the screw thread 11a formed thicker than the width of the screw groove 14 contracts, and both sides of the screw thread 11a are brought into pressure contact with the screw groove 14 due to the restoring force generated accordingly. This prevents loosening of the screws. Bolt 1
Since the thread 11b conforming to the standard is provided on the tip 10a side of No. 0, the bolt 10 can be easily inserted into the nut 13 at the start of fastening.

FIG. 2 shows a second embodiment of the present invention. In this example, at the top of the thread 16a of the nut 15,
A groove 17 extending along the thread 16a is formed.
The groove 17 is not formed in the screw thread 16b around the inlet 15a of the nut 15 and several times around, and the thickness of the screw thread 16b in this range is a value according to the standard of the screw. On the other hand, the thickness of the thread 16a in the portion having the groove 17 is set to be larger than the above-mentioned standard. The thread groove 19 of the bolt 18 is made standard, whereby the thickness of the thread 16a is larger than the width of the thread groove 19.

In this embodiment, the bolt 18 and the nut 15
When and are screwed together, the groove 17 of the screw thread 16a formed thicker than the width of the screw groove 19 contracts, and the restoring force generated thereby causes the opposite sides of the screw thread 16a and the screw groove 19 to come into pressure contact with each other. . This prevents loosening of the screws. Since the standard thread 16b is provided on the inlet 15a side of the nut 15, the bolt 18 can be easily inserted into the nut 15 at the start of fastening.

FIG. 3 shows a third embodiment of the present invention. In this example, a groove 22 extending along the thread 22 is formed at the top of the thread 21 of the feed screw 20 that drives the stage S of a machine tool or the like. The thickness of the thread 21 is set larger than the standard of the screw, and the width of the thread groove 24 of the nut 23 screwed with the feed screw 20 is the same as the standard of the above-mentioned screw.

Also in this example, when the screw thread 21 and the screw groove 24 are screwed together, the groove 22 of the screw thread 21 contracts, and the restoring force resulting from this contracts both sides of the screw thread 21 against the screw groove 24.
Therefore, the backlash between the feed screw 20 and the nut 23 is removed, and the feed accuracy of the stage S is improved.
Incidentally, as in the second embodiment, the thread groove 25 of the feed screw 20 is formed.
May be formed in accordance with the standard, the thread 26 of the nut 23 may be formed larger than the standard, and a groove may be formed at the top thereof.

FIG. 4 shows a table positioning mechanism using the screw of the present invention. In this positioning mechanism, one bolt 32 is screwed into each nut 31 arranged on each side of the rectangular fixed table 30, and the tip of each bolt 32 is positioned at a desired position on the fixed table 30. The position of the movable table 33 is fixed by abutting against the end surface of the movable table 33. In the above mechanism, the thread of the bolt 32 or the nut 31 is formed thicker than the width of the opposite thread groove, and a groove extending along the thread is formed at the top of this thread. As a result, the bolt 32 and the nut 31 are securely prevented from loosening, so that it is not necessary to overlap the nut 31 with a lock nut to prevent the loosening. Therefore, when changing the position of the movable table 33, only the bolt 32 needs to be operated, and the work efficiency is greatly improved.

[0015]

As described above, according to the present invention, parts such as washers are used because both sides of the screw thread are pressed against the screw groove by the restoring force caused by the displacement of the groove formed on the top of the screw thread. Without loosening or rattling of the screw, it is possible to significantly improve the work efficiency when the screw is attached or detached. Since the washers and the like can be omitted, it is effective in reducing the weight when a large number of screws are used. In the conventional method of fastening using washers, when the screws are loosened beyond the range where the washers have the function of preventing loosening, there is no force for restraining the looseness and the screws fall off easily. According to the above, since the force for preventing loosening always acts regardless of the positional relationship between the nut and the bolt, even if loosening occurs in the bolt or the tightening force of the bolt is weak,
The screw retains its current position and prevents the bolt from falling off.

[Brief description of drawings]

FIG. 1 is an axial sectional view of a screw according to a first embodiment of the present invention.

FIG. 2 is an axial sectional view of a screw according to a second embodiment of the present invention.

FIG. 3 is an axial sectional view of a screw according to a third embodiment of the present invention.

4A and 4B are views showing a positioning mechanism to which the screw of the present invention is applied, in which FIG. 4A is a plan view and FIG. 4B is a side view from the IV direction in FIG. 4A.

FIG. 5 is a view showing an example of conventional loosening prevention in a fastening mechanism using screws.

FIG. 6 is a view showing an example of conventional rattling prevention in a feeding mechanism using screws.

[Explanation of symbols]

 11a, 16a, 21 Threads on which grooves are formed 12, 17, 22 Grooves formed on top of threads 14, 19, 24 Thread grooves

Claims (1)

[Claims] 1. The thickness of the thread is set to be larger than the width of the thread groove screwed with the thread, and a groove extending along the thread is formed at the top of the thread. screw.