JPS61157813A - Removing preventive type crossed hole 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 Industrial Application) The present invention is a non-removable type that can be tightened with a standardized standard tightening tool (such as a Phillips screwdriver). Regarding cross recessed screws.

(Prior art) General cross recessed screws are JI screws that are commercially available and available to anyone.
Tightening and removal can be performed freely using a Phillips screwdriver standardized by S or ISO standards.

However, in the case of screws used in places that should not be touched without permission, such as adjustment points or dangerous places, it is required that the screws cannot be easily loosened or removed using the standard tools mentioned above. Ru. In response to this demand, various types of anti-removal screws have been proposed.One of them is a Phillips screwdriver locking groove provided in the screw head, which works only in the tightening direction with a standard screwdriver, but not in the loosening direction. Some screws are designed so that they do not work, and the screws must be removed using a special screwdriver. For example, in the method disclosed in Japanese Utility Model Application Publication No. 59-144213, the effective depth of the cross recess is formed deeper than the standard value, and the loosening direction of the locking groove is off, and the bonding surface is This is a tapered wall surface that gradually becomes shallower in the loosening direction, with the depth of the opening being the starting point.

Therefore, with a standard tightening tool, its tip does not reach the bottom side of the cross recess and does not fit into the wall surface located in the loosening direction of the locking groove, so that removal can be prevented.

Furthermore, in the device disclosed in Japanese Utility Model Application Publication No. 59-144213, the length along the radial direction of the locking groove is formed with a cross recess longer than the standard value, and the locking groove is located in the loosening direction. The wall surface is a tapered wall surface that gradually becomes shallower from the standard value position toward the center toward the loosening direction.

Therefore, with a standard tightening tool, the side surface of the tightening tool does not fit into the wall surface located in the loosening direction of the locking groove, so that removal can be prevented.

(Problems to be Solved by the Invention) However, in all of the above conventional types, when tightening work is performed using a standard tightening tool, the tip of the tool is located in the loosening direction of the locking groove. Since it is not fitted to the wall surface to be used, it has poor bite, and even if you try to attach the cross recess to the tool, it will easily fall off, which poses a problem for work. Also, eliminating this problem requires the use of expensive special tightening tools similar to those used for removal. Therefore, in the present invention,
Good bite even when using standard tightening tools when tightening.
The object of the present invention is to provide a cross-recessed screw that cannot be removed using standard tightening tools.

(Means for Solving Problems) The gist of the present invention is to set the effective depth of the cross recess to a standard value compatible with a standard tightening tool, and to fit the bottom peripheral wall of the cross recess with the tip of the tool. Among the wall surfaces that form the bite portion and are continuous with the bite portion, the wall surface located in the loosening direction of each locking groove,
It has an inclined flank surface that disengages from the tool, so that even a standard tightening tool can be used during tightening work, resulting in good workability. When the tool is rotated in the loosening direction and the torque exceeds a predetermined value, the tool protrudes from the biting portion onto the inclined flank surface to prevent removal.

(Example) Examples of the present invention will be described above based on the drawings. 1st
Figures 3 to 3 are views of the first embodiment, in which the head 2 of the screw 1 is provided with four locking grooves 3 extending radially in the radial direction, and the locking grooves 3 are connected to each other at the center. A cross recess 4 is carved in communication. The outer diameter dimension M and the inner diameter dimension G between the opposing locking grooves 3 are the same as the standard values defined by JIS etc., and the effective depth L from the opening surface of the cross recess 4 is also the same as the standard value. It is configured.

Further, the spaces between the adjacent locking grooves 3 are continuous by a plurality of wall surfaces that act on the received standard tightening tool 5, and the wall surfaces are formed in a tapered shape along the effective depth L.

The wall surfaces include first to fourth wall surfaces 6, 7, 8, 9 that fit on the front end side of the tightening tool 5 on the bottom side of the cross recess 4.
A biting portion is formed by the screws, and each of these wall surfaces, at least as far as the bottom side is concerned, is formed in the same manner as the standard value of a standard cross-recessed screw.

It extends from the bottom side to the opening surface of the cross recess 4 while gradually increasing the width while keeping a constant taper angle.

The second wall surface 7 extends continuously from the bottom side to the opening surface at a constant taper angle, and is provided at a predetermined depth and gradually narrows its width from the intersection a to the opening surface. They intersect at the provided intersection d. The first wall surface 6 and the second wall surface 7 constitute a wall surface that transmits torque in response to the action in the tightening direction of the screw.

Next, the third wall surface 8 is completed at the intersection point a and the intersection point A provided at approximately the same depth. The fourth wall groove 9 extends continuously from the bottom side at a constant taper angle, and gradually narrows its width from the intersection point to the intersection point C provided in the middle of the locking groove 3. Cross and complete.

Then, the second wall surface 7, the third wall surface 8 and the fourth wall surface 9
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The wall surface 10 constitutes a first relief surface having an inclined shape that makes the fit with the standard tightening tool 5 gradually shallower along the opening side of the cross recess and the loosening direction.

Further, a sixth wall surface 11 is provided adjacent to the wall surface 10. The wall surface 11 is a triangular area surrounded by the intersections c and d and the intersection e provided at the opening surface of the cross recess 4, and is formed to have a larger taper angle than the fifth wall surface 10. In addition, the locking groove 3 is continuous with an arcuate curve, thereby forming a second flank surface that cooperates with the first flank surface. Note that the screw shaft portion and the like are similar to those of a conventional cross-recessed screw, so illustration and description thereof will be omitted.

The anti-removal type cross-recessed screw 1 of the first embodiment with the above configuration has the screws provided by the first to fourth wall surfaces 6, 7, 8, and 9 into which the standard tightening tool 5 is fitted on the bottom side of the cross-recess 4. Since it has a retaining part, the screw does not fall out during tightening, and can be handled in the same way as a normal cross-recessed screw.

Then, when the tool 5 is rotated in the tightening direction, rotational torque is transmitted to the screw by the first and second wall surfaces 6 and 7, so that tightening can be performed. Further, when the tool 5 is rotated in the loosening direction, when the torque exceeds a preset value, the tool is guided to the second flank surface continuous to the locking groove 3, that is, the 59th surface 10. In this way, it approaches the sixth wall surface ill from the third wall surface 8 and the fourth wall surface 9 and separates from it.

Therefore, it cannot be loosened or removed unless a specially shaped tightening tool that fits the cross recess 4 is used.

The depth Ll of the biting portion is 1/4 to 1/2 of the effective depth L of the cross recess 4, and the inclination angle of the first flank is 17 to 30 degrees with respect to the axial direction of the screw. It is desirable to do so.

Next, FIGS. 4 to 6 show a second embodiment of the present invention, in which the same parts as in the first embodiment are given the same reference numerals for easy understanding. In the cross recessed screw 12 of this embodiment, the sixth wall surface 11 constituting the second flank is omitted,
The fifth wall surface 10 constituting the first flank is extended by that amount. That is, the second
These intersection points a and b are adjacent to the wall surface 7, the third wall surface 8, and the fourth wall surface 13 whose terminal end is extended to the intersection point e.

A fifth wall surface 14 is formed in a trapezoidal area surrounded by C, and the wall surface 14 is inclined so that the fitting with the standard tightening tool 5 becomes gradually shallower along the opening side of the cross recess and the loosening direction. This constitutes a shaped flank.

Therefore, since this fifth wall surface 14 is not directly continuous with the locking groove 3, a larger rotational torque is required to make the tool protrude than that of the first embodiment, but the inclination angle etc. All you have to do is make it bigger.

(Effects of the Invention) As is clear from the above embodiments, the anti-removal type cross recessed screw of the present invention allows good tightening work even with standard tightening tools without impairing the biting during tightening. In addition, it provides a novel effect that cannot be obtained with conventional tightening tools, in that it cannot be loosened or removed using standard tightening tools.

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention; FIG. 1 is a front view of the first embodiment, and FIG.
3 is a sectional view taken along line I-1, FIG. 4 is a front view of the second embodiment, FIG. 5 is a sectional view taken along line ■-V in FIG. It is a sectional view taken along the line ■-■. [Explanation of symbols] 1.12... Screw 2... Head 3... Locking groove 4... Cross recess 5... Tightening tool (standard) 6-11, 13, 14 ...Wall surfaces a, b, c, d, e...intersection points Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. In a screw with a cross recess formed in the screw head with four locking grooves extending radially in the radial direction, the cross recess has an effective depth of a standard value that is compatible with standard tightening tools. The bottom circumferential wall of the cross recess forms a biting part that fits with the tip of a standard tightening tool, and a part of the wall that extends from the biting part to the opening side to loosen each of the locking grooves. A removable cross-recessed screw characterized in that a wall surface located in the direction forms an inclined relief surface that becomes shallower gradually along the opening side of the cross-recess and the loosening direction.