JPH0565724B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The anti-removal type cross-recessed screw of the present invention can be tightened using a standardized standard tightening tool (such as a Phillips screwdriver). However, once tightened, the screw head should be locked so that it cannot be removed using the standard tightening tool and can only be removed using a special tightening tool. This invention relates to a non-removable cross recessed screw with a stop groove formed therein.

(Prior Art) Ordinary cross-recessed screws can be freely tightened and removed using a Phillips screwdriver standardized by JIS or ISO standards, which is commercially available and available to anyone. 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.

For this purpose, various types of anti-removal screws have been proposed, one of which is a Phillips screwdriver locking groove provided in the screw head that acts only in the tightening direction with a standard screwdriver, but not in the loosening direction. Some screws are designed so that they cannot be removed, and the screws must be removed using a special screwdriver.

For example, in the device disclosed in Japanese Utility Model Application No. 59-144213, the effective depth of the cross recess is formed deeper than the standard value, and the wall surface located in the loosening direction of the locking groove is at the standard value of the cross recess. The wall surface is tapered to become shallower in the loosening direction with the starting point at the lower position. Thereby, the tip of the standard tightening tool does not reach the bottom side of the cross recess and is not fitted into the wall surface located in the loosening direction of the locking groove, so that removal can be prevented.

In addition, 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 that is 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. Thereby, the side surface of the standard tightening tool does not fit into the wall surface located in the loosening direction of the locking groove, so that removal can be prevented.

(Problem to be Solved by the Invention) In all of these conventional anti-removal type cross recessed screws, when tightening work is performed using a standard tightening tool, the tip of the tool is positioned in the loosening direction of the locking groove. Since the shape does not fit and lock onto the wall surface, the bite is poor, resulting in the following problems.

For example, when a tool is inserted into a cross recess in a normal cross recessed screw, the tool bites into each wall surface located in both the tightening direction and the loosening direction of the locking groove while being fitted and locked. Since it is self-retaining and does not fall off, tightening work can be easily performed with one hand.

However, with the configuration of the conventional anti-removal type cross recessed screw described above, it is not self-retaining and easily falls off, so the screw must be supported with the hand opposite to the hand operating the tightening tool to prevent it from falling off. It won't happen. For this reason, work efficiency is significantly reduced, and work that requires supporting the fastening plate with the other hand, and screws that are sequentially supplied while being held by a screw supply belt, for example,
There were problems such as the fact that it could not be used for fastening work using an automatic screw driver such as the one disclosed in Publication No. 60667.

Therefore, in the present invention, a cross-recessed locking groove is formed to prevent removal so that it has good bite and self-retention when tightened using a standard tightening tool, and cannot be removed using the standard tightening tool. The purpose is to provide cross-recessed screws.

(Means for Solving the Problems) In order to solve the above problems, in the anti-removal type cross recessed screw of the present invention, the cross recesses are formed to an effective depth of a standard value that is compatible with standard tightening tools. The bottom side of the cross recess is provided with walls into which the tip of a standard tightening tool is fitted to lock the locking groove in both the tightening and loosening directions. A biting part is formed at the tip of the tightening tool to self-hold the screw, and among the walls of this biting part, the wall surface located in the tightening direction is continuous to the opening side of the cross recess to transmit the tightening rotational torque. The wall surface located in the loosening direction is continuous with the opening side of the cross recess and the sloped relief surface that becomes shallower along the loosening direction so that the wall surface located in the loosening direction can be detached with a predetermined loosening rotation torque or more. .

(Example) Examples of the present invention will be described above based on the drawings. 1 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 interconnected at the center. A cross recess 4 is carved in communication with the. And the outer diameter dimension M and inner diameter dimension G between each opposing locking groove 3
is the same size as the standard value defined by JIS etc., and the effective depth L from the opening surface of the cross recess 4 is also configured to be the same as the standard value.

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. There is. The wall surface has a biting portion formed on the bottom side of the cross recess 4 by each of the first to fourth wall surfaces 6, 7, 8, and 9 that fit on the front end side of the tightening tool 5, Each of these walls, at least as far as the bottom side is concerned, is formed in the same way as the specifications for a standard cross-recessed screw.

The first wall surface 6 has the same shape as that of a standard cross-recessed screw, and extends from the bottom side to the opening surface of the cross-recessed hole 4 while gradually widening the width while maintaining 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 the opening surface while gradually narrowing its width from an intersection point a provided at a predetermined depth. They intersect at intersection d. The first wall surface 6 and the second wall surface 7 constitute a wall surface that receives the action in the tightening direction of the screw and transmits torque.

Next, the third wall surface 8 includes the intersection a and an intersection b provided at a depth approximately equal to the intersection a.
Complete at position. The fourth wall surface 9 extends continuously from the bottom side at a constant taper angle, and gradually narrows its width from the intersection point b until it intersects at the intersection point c provided in the middle of the locking groove 3. and complete.

The intersections a, b, c, and d are adjacent to the second wall surface 7, the third wall surface 8, and the fourth wall surface 9, respectively.
A trapezoidal area surrounded by a trapezoidal area forms a fifth wall surface 10, and the wall surface 10 has an inclination that gradually makes the fit with the standard tightening tool 5 shallower along the opening side of the cross recess and the loosening direction. It constitutes a first flank having a shape.

Further, a sixth wall surface 11 is provided adjacent to the wall surface 10. The wall surface 11 is located at the intersections c and d.
and the intersection e provided on the opening surface of the cross recess 4.
A triangular area surrounded by a triangle having a larger taper angle than the fifth wall 10,
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 cross recessed screw 1 of the first embodiment with the above configuration has first to fourth wall surfaces 6 on the bottom side of the cross recess 4 on which the tip end of a standard tightening tool 5 is fitted and locked. 7, 8, and 9, so that when the tool 5 is inserted into the cross recess 4, the tip side of the tool 5 is connected to each wall surface 6, 7 located in the tightening direction of the locking groove 3 and each wall surface located in the loosening direction. Since it bites into both the wall surfaces 8 and 9 in a fitted and locked state, it is self-retained without falling out like a normal cross-recessed screw.

Therefore, when the tool 5 is rotated in the tightening direction in this state, the first and second tools positioned in the tightening direction are rotated.
Since rotational torque is transmitted to the screw by the respective wall surfaces 6 and 7, tightening work can be performed in the same way as in the case of a normal cross-recessed screw.

In addition, in this anti-removal type cross-recessed screw 1, each wall surface 8, 9 located in the loosening direction is completed halfway to the bottom side of the cross-recess 4, so once tightened, the anti-removal type cross-recessed screw 1 is When the tool 5 is inserted into the cross recess 4 and rotated in the loosening direction in order to remove it, when the torque exceeds a preset value, the tool will be released from the fitting lock of each wall surface 8, 9. It separates and rises above the second flank, that is, the fifth wall surface 10 that is continuous with the locking groove 3, and this fifth wall surface 10
The removal prevention effect is performed by rotating idly along the sixth wall surface 11 side while being guided by.

Therefore, in order to remove the anti-removal cross recessed screw 1 from the fastening member, it must be loosened or removed unless a specially shaped tightening tool that perfectly matches the shape of each locking groove 3 of the cross recess 4 is used. It is not possible.

The depth _L1 of the biting portion is 1/4 to 1/2 of the effective depth L of the cross recess 4, and the angle of inclination of the first flank is 17 to 30 with respect to the axial direction of the screw. It is desirable to set it as a degree.

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, and the fifth wall surface 10 constituting the first flank is extended by that amount. It is.

The locking groove 3 of this cross-recessed screw 12 has the first and second wall surfaces 6 and 7 located in the tightening direction, and the third wall surface 8 of each wall surface located in the loosening direction. The other wall surface 13, which is formed in the same manner as in the embodiment and located in the loosening direction, is the third wall surface 8 which is the starting end.
The protrusion height is gradually reduced from the intersection point b with the groove to the opening side, and the groove is extended in such a manner that it converges to the intersection point e, which is the terminal end, while decreasing the protruding height so that the depth of the groove becomes gradually shallower.

Further, the second wall surface 7, the third wall surface 8 and the fourth wall surface
A fifth wall surface 14 is formed in a trapezoidal area adjacent to the wall surface 13 and surrounded by these intersection points a, b, e, and d,
The wall surface 14 constitutes an inclined relief surface that makes the fit with the standard tightening tool 5 gradually shallower along the opening side of the cross recess and the loosening direction.

Also in the case of the cross recessed screw 12 of this second embodiment,
As in the first embodiment, the bottom side has a biting part formed by each of the first to fourth wall surfaces 6, 7, 8, and 13 on which the tip of the standard tightening tool 5 fits and locks. When the tool 5 is inserted into the cross recess 4, its tip side is fitted and locked to both the wall surfaces 6, 7 located in the tightening direction of the locking groove 3 and the wall surfaces 8, 13 located in the loosening direction. Since it bites in the state, it is self-retained without falling out like a normal cross recessed screw.

Therefore, when the tool 5 is rotated in the tightening direction in this state, the first and second tools positioned in the tightening direction are rotated.
Since rotational torque is transmitted to the screw by the respective wall surfaces 6 and 7, tightening work can be performed in the same way as in the case of a normal cross-recessed screw.

Also, for each of the wall surfaces 8 and 13 located in the loosening direction, one wall surface 8 is completed halfway to the bottom side of the cross recess 4, and the groove depth of the other wall surface 13 gradually becomes shallower toward the opening side. The protrusion height is reduced as shown in the figure, so once tightened, the cross recessed screw 1
When the tool 5 is inserted into the cross recess 4 and rotated in the loosening direction in order to remove the It separates from the locking groove 3 and rises above the flank surface, that is, the fifth wall surface 14 adjacent to the locking groove 3, and rotates idly along the fifth wall surface 14 to perform a removal prevention action.

Therefore, in order to remove the anti-removal cross-recessed screw 12 from the fastening member, it must be loosened or removed unless a special-shaped tightening tool that perfectly matches the shape of each locking groove 3 of the cross-recess 4 is used. It is not possible.

Incidentally, since the fifth wall surface 14 in this second embodiment is not directly continuous with the locking groove 3, a larger rotational torque is required to push the tool out than in the first embodiment. The inclination angle etc. may be increased by that amount.

(Effects of the Invention) As is clear from the above embodiments, the anti-removal cross recessed screw of the present invention can be expected to have the following effects that solve the problems of the prior art.

This anti-removal type cross-recessed screw has a locking groove on the bottom side of the cross-recess formed at the effective depth of the standard value that is compatible with standard tightening tools. The tip of the inserted standard tightening tool is fitted into the biting part of each wall surface provided in such a manner that the screw is self-retained.
When tightening, it can be easily tightened with one-handed rotation, just like with standard cross-recessed screws.

In addition, unlike the prior art non-removable cross recessed screw, it is particularly useful for operations that require the fastening plate to be supported with the other hand, or for screws that are sequentially supplied while being held in place by a screw supply belt. It can also be used for fastening work using an automatic screw driver such as that disclosed in Japanese Utility Model Application Publication No. 4-60667.

In addition, the wall surface located in the tightening direction of the locking groove is continuous to the opening side of the cross recess, forming a transmission habit of tightening rotational torque, so it can be rotated in the tightening direction using a standard tightening tool. In addition, the wall surface located in the loosening direction can be tightened as well as the cross-recessed screw. By making it continuous with the sloped flank that becomes shallower, when a standard tightening tool is rotated in the direction of loosening, the tip of the tightening tool will become stuck when the torque exceeds a specified level. Since it protrudes from the slanted relief surface, it can be prevented from being removed using standard tools, and when loosening or removing it, a special dedicated tool with the same shape as the locking groove is used.

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention; FIG. 1 is a front view of the first embodiment, FIG. 2 is a sectional view taken along the line - - in FIG. 1, and FIG.
4 is a front view of the second embodiment, FIG. 5 is a sectional view taken along the - line in FIG. 4, and FIG. 6 is a sectional view taken along the - line in FIG. [Explanation of symbols], 1, 12... Removal prevention cross recessed screw, 2... Head, 3... Locking groove, 4... Cross recess, 5... Tightening tool (standard), 6 ...First
Wall surface, 7...Second wall surface, 8...Third wall surface, 9,1
3...Fourth wall surface, 10,14...Fifth wall surface (first
flank surface), 11...6th wall surface (second flank surface),
a, b, c, d, e...intersection.

Claims (1)

[Claims] 1. A screw in which a cross recess is formed in the head of the screw with four locking grooves extending radially in the radial direction for inserting a tightening tool, and the cross recess is compatible with a standard tightening tool. The tip of a standard tightening tool is fitted into the bottom side of this cross recess to provide a depth that is the effective depth of the standard value. Wall surfaces are provided, and each of these wall surfaces forms a toothed portion that self-retains a screw at the tip of a standard tightening tool, and among the wall surfaces of this toothed portion, the wall surface located in the tightening direction has a cross shape. The walls are continuous to the opening side of the hole to form a transmission wall for the tightening rotational torque, and the wall surface located in the loosening direction is formed along the opening side of the cross recess and the loosening direction so that the wall surface located in the loosening direction is detached by a predetermined loosening rotation torque or more. A removable cross-recessed screw that is characterized by a continuous sloped flank that gradually becomes shallower.