JPS5989814A - Fixed-torque clamping screw - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a tightening screw for fixing equipment, and in particular, to
In order to prevent deformation or damage to the equipment being tightened, appropriate constant tightening is recommended for tightening screws that generate force.
- Use a screw with a constricted part on the screw head and limit the torque by breaking the constricted part when the load torque exceeds a certain value, or use a torque wrench, torque driver, etc. A tool is used to tighten the torque.

The screw provided by the constricted portion has the disadvantage that it breaks after being tightened once and cannot be reused. In addition, the general usage of a torque wrench or torque driver is to set it on a screw when tightening, and then remove it after tightening is completed.For example, when using a torque wrench or torque driver to tighten equipment with a tool, The disadvantage was that it took time to attach and detach these devices to the screws, which significantly reduced work efficiency.Furthermore, torque wrenches and torque drivers had the disadvantage of requiring a large amount of space around the tightening screws. [Object of the Invention] The object of the present invention is to provide a screw that can be used repeatedly when tightening equipment with a screw, and that can be tightened with a constant torque without using tools such as a torque wrench or torque driver. It's about doing.

[Summary of the invention]

In order to achieve the above object, the constant torque tightening screw according to the present invention is composed of a screw head provided with an inclined part, a steel ball in contact with the inclined part, and a compression coil spring that applies preload to the steel ball. It is characterized in that the acting force generated by torque is applied to the steel ball through the inclined portion, and the torque is transmitted when tightening to a predetermined level based on the force relationship between the preload and the acting force of the inclined portion.

[Embodiments of the Invention] Eleven embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

The constant torque tightening screw according to this embodiment, as shown in the side sectional view of FIG. A compression coil spring (hereinafter referred to as spring) 1 and a steel ball 2 with a small diameter hole are inserted into it.

The amount of deflection of the spring 1 changes by inserting a tool such as a wrench into the hole 3d of the screw head 3 and turning the screw 6, so that the force W pushing the steel ball 2 can be adjusted. Also, retaining ring 4
The purpose of this is to prevent the screw body 5 and the screw head 3 from separating. Furthermore, screw M3 is shown in Fig. 2 (A-'A in Fig.
As shown in cross-section), a recess is provided in the inner circumferential wall 3a, and has inclined portions s and b having an inclination of θ at one end, and an arcuate portion 3c whose other end is in contact with the inclined portion 5bK.

When the screw head 3 is turned in the tightening direction of the screw body 5 (clockwise in the case of a right-handed screw), the state shown in FIG. 2 is obtained.

In other words, the tightening applied to the screw head 3 is torque.

The screw body is turned until the corresponding force T becomes greater than the repulsive force of the spring 1. Next, when the constant tightening determined by the screw ring 7 exceeds the torque, the steel ball 2 compresses the spring 1 and becomes the state shown in FIG. 3, and the inner peripheral wall 3 of the screw head 3
a rolls, and the screw head 3 rotates idly 0 The force of the spring 1 pushing the steel ball 2 - 1 The inclination angle of the inclined part 3b is θ, and the point where the steel ball 2 touches the inner peripheral wall 3a from the center of the screw head 3 If the distance to is L, then the torque T just before the screw head 3 starts idling can be roughly determined by the following (1).

T=W-CO8θ・SiNθ・L...(1) Formula (
1) As can be seen from the formula, by adjusting W,
When the screw head 3 is turned in the direction of loosening the screw body 5 (counterclockwise in the case of a right-handed screw), it becomes like the part shown in Fig. 4. That is, the steel ball 2 is placed in the recess 3C of the inner circumferential arm 3a of the screw head 3, and the force applied to the loosening torque rotates the screw body 5 without compressing the spring 1.

Next, FIG. 5 shows a state where the tightening is turned in the direction when the slope portion 3b and the arcuate portion 3C are reversed. In this case, if the screw head 3 is turned in the tightening and loosening direction without idling according to the same principle as in the state shown in FIG.
In the same state as shown in the figure, the screw head 3 rotates idly and the screw body 5 does not rotate.

When loosening, as shown in Fig. 6, the holes in the screw head 3 and the screw body 5 are on the same line! Ie and 5/eK connecting pin 7
When the screw head 3 and the screw body 5 are connected, it can be loosened by K. In the above embodiment, the force of pressing the steel ball into the recess of the screw head by a spring is used. When the torque exceeds the specified value, a part of the screw will come loose (
b) An embodiment has been shown, but the present invention provides +4
However, if the screw head is tightened to a predetermined torque or more, constant torque tightening includes all screws that have a structure that rotates when force is applied. [Effects of the Invention] The present invention According to the above, when tightening a device with a screw, if the torque exceeds a predetermined value, the screw head will slip and the torque transmission to the main body can be cut off. Can be tightened to a constant torque repeatedly without using tools. Furthermore, the tightened screw has the effect that it is impossible to loosen it without inserting a previously prepared piston. Another advantage is that the torque value can be adjusted.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of an embodiment of a constant torque tightening screw according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. - Figure 4 is a cross-sectional view taken along the line A and shows the state in which it is idling; Figure 4 is a cross-sectional view taken along the line A-A in Figure 1 and shows the loosened state; Figure 5 is a cross-sectional view taken along the line A-A in Figure 1, and shows the loosened state.
FIG. 6 is a cross-sectional view showing a tightened state, and FIG. 6 is a cross-sectional view taken along the line AA in FIG. 1, showing a loosened state. Explanation of symbols 1... Compression coil spring, 2...
Steel ball, 3... Screw head, 4... Retaining ring, 5... Screw body, 6... Spring force adjustment screw, 7...・・・
Connecting bins. 1st Prisoner 2 Prisoners 3m ;+-4 figure

Claims (2)

[Claims] (1) A constant torque tightening screw having a screw body with a thread formed thereon and a screw head that is connected to the screw body and supplies rotational force to the screw body. 1. A constant torque tightening screw, characterized in that a constant torque supply means is provided for supplying rotational torque to a screw main body only when the rotational torque is within a predetermined torque. (2) In the constant torque tightening screw according to claim 1, the constant torque supplying means includes a recess provided with a tendency on an inner surface of the screw head that is in contact with the screw head portion, and A constant torque tightening screw characterized by comprising a spherical part #4 that is pressed into the recessed part of the screw head with pressurization from the main body part.