WO2011129026A1

WO2011129026A1 - Screw driving hole

Info

Publication number: WO2011129026A1
Application number: PCT/JP2010/066500
Authority: WO
Inventors: 慎悟鳥居; 利昌豊岡
Original assignee: 日東精工株式会社
Priority date: 2010-04-16
Filing date: 2010-09-24
Publication date: 2011-10-20
Also published as: CN102859212A; CN102859212B; JP2011226520A; MY164227A; JP5060582B2

Abstract

Disclosed is a screw driving hole, the shape of which can maintain the appearance of a coated screw when the coated screw is fastened by a driver bit. In a screw having a criss-cross driving hole (2) in which a driver bit (30) is to be engaged, stepped side walls (20) are formed on the surfaces of the head portions of both side walls defining engagement groove (10) extending from the center in the criss-cross direction so that the stepped side walls have a wide gap (L) therebetween. Furthermore, planar engagement side walls (11) having a width similar to that of the criss-cross engagement groove (10) in the normal state are formed on the bottom surface side of the engagement groove (10). The stepped side walls (20) are integrally connected to the planar engagement side walls (11). Thus, the driver bit does not act on the vicinity of the head portion surface of the engagement groove when the driver bit is engaged in the engagement groove to fasten a screw. Accordingly, the head portion surface tends not to deform, and the coating is not peeled or detached, and thus, the appearance of a product assembled by this screw is completely prevented from being spoiled.

Description

Screw hole drive hole

The present invention prevents peeling of a painted part in the vicinity of an engaging groove in which a cross-shaped drive hole is formed, particularly when a screw having a head painted is tightened in a screw part that is fastened to a workpiece with a predetermined screw tightening force. The present invention relates to a screw hole drive hole.

Generally, when a screw having a cross-shaped drive hole on the head is tightened to a workpiece, a cross-shaped driver bit that can be fitted into the cross-shaped drive hole is engaged, and then the driver bit is It is tightened to the work by rotating in the screw tightening direction. Recently, in such a screw, it is important to improve the aesthetics of a product made of a work assembled with the screw by baking a paint on the head of the screw due to the color relationship with the work. Such screw heads are painted by aligning a number of screws with the heads facing up and spraying paint from above the screw heads using a spray gun. For this reason, it is painted in the vicinity of the head surface of the drive hole together with the head surface, but the interior of the drive hole is not painted as it becomes deeper.

However, the screw used in the operation of tightening such a screw to the workpiece is baked on the head 103 having a normal drive hole shape as shown in FIGS. When the tightening force is applied by engaging the driver bit 130, the engaging blade 131 of the driver bit 130 comes into contact with the side wall on the head surface side of the engaging groove 110, and even if the vicinity of the side wall of the engaging groove 110 is slight. When it is deformed by rising or the like, as shown in FIG. 11, the paint applied to the engagement groove of the drive hole is lifted or scraped off, and the paint on the head surface near the engagement groove of the drive hole is peeled off. The appearance of the screw head appearance is impaired. Particularly in recent years, devices such as printers and digital cameras used by general users are required to give a good impression to the user in color, and if such paint peeling occurs, the number of defective products increases. The peeling of the screw head paint is a major problem of product failure.

In order to solve this problem, recently, measures such as improving the adhesion of the paint and improving the shape of the screw head drive hole have been taken, but no solution has been found yet. Under such circumstances, although there is a direct relationship with the screw to be coated, there is a screw having a shape that prevents the plated layer in the cross hole portion from being damaged as disclosed in, for example, Japanese Utility Model Publication No. 7-6512. . This is a shape as shown in FIG. In other words, the tip edge of the corner 206 formed at the intersection of the cross hole 202 is chamfered so as not to hit the valley bottom 231 of the driver bit 230.

Japanese Utility Model Publication No. 7-6512

However, in such a screw having a drive hole, since the space between the base of the blade of the driver bit and the intersection of the drive hole of the screw is wide, the insertion of the driver bit is facilitated and the camout is also reduced. Although it was considered that it is effective for a painted screw because it has the advantage that it does not easily occur, there are still problems such as paint floating due to slight deformation of the head surface during screw tightening and scraping of the paint. This is an effective shape for the one that has a certain level of strength, such as this conventional example, but since the paint is just baked on the surface by spraying the paint, the screwdriver at the time of screw tightening If deformation such as the head surface swells even a little due to the driving force of the bit, this is because it cannot withstand this. For this reason, problems still remain, such as the inability to provide screws that maintain the aesthetics of painting with the current screw drive holes.

An object of the present invention is to obtain a drive hole shape capable of solving such problems and maintaining the aesthetics of a painted screw at the time of screw tightening with a driver bit.

An object of the present invention is to provide a screw part having a cross-shaped drive hole 2 with which a cross-shaped driver bit 30 engages, and the head surface side of both side walls constituting the engaging groove 10 extending in the cross direction from the center. On the other hand, a stepped side wall 20 having a wide gap (L) on the surface side is formed on the bottom surface, and a flat engagement side wall having a width similar to that of a normal cross-shaped engagement groove 10 on the bottom surface side of the engagement groove 10. This is achieved by forming the drive hole 2 having a structure in which the stepped side wall 20 and the planar engagement side wall 11 are integrally connected.

In the above invention, the stepped side wall is a straight flat surface in a part or all of the stepped side wall, or the stepped side wall is a shape in which a part or all of the cross section is formed into a concave or convex curved surface. It may be either.

According to the present invention, the coating of the screw head is performed in such a manner that a number of screws are aligned with the head facing up, and the paint is sprayed and applied from above the screw head with a spray gun. At this time, the paint also enters the drive hole, but the paint is hardly applied as it gets deeper. As a result, the coating thickness is the normal thickness on the head surface side. On the other hand, since the engaging groove is wider on the head surface side than the normal engaging groove, even if the driver bit engages with this engaging groove and drives the screw to tighten, Since the driver bit does not act near the head surface, there is almost no deformation on the head surface, and this screw tightening process peels off the paint or floats the paint, damaging the aesthetics of the product assembled with this screw. There will be nothing. In addition, since the coating of the screw is prevented from being damaged when the screw is tightened, the quality defect of the assembled product is drastically reduced and the disposal of the defective product is also reduced. Furthermore, in the manufacture of such a screw, only the shape of the head forming punch used in the conventional forging is changed, so that there is an advantage that it can be provided at low cost without increasing the manufacturing cost. Moreover, since the stepped side wall is formed with a slight depth from the head surface of the screw, it hardly affects the screw tightening action when the driving force at the time of screw tightening is transmitted from the engagement blade of the driver bit. It is possible to obtain a unique effect such as not occurring.

It is a top view which shows the head of the screw | thread of 1st Example which is embodiment of this invention. It is a principal part cross-sectional front view which shows the stepped side wall of the drive hole which concerns on this invention. It is a principal part expanded sectional view which shows the state which engaged the driver bit with the drive hole. It is an expanded sectional view showing a part of drive hole of the present invention. It is a plane photograph which shows the head after the screw fastening of this invention. It is principal part sectional front view which shows 2nd Example of this invention, and a part of stepped side wall is parallel to the centerline of a screw. It is principal part sectional front view which shows the modification of this invention, (A) shows the outline where the stepped side wall became the concave curved surface shape, (B) is the concave shape from the intermediate part of the stepped side wall below (C) shows a contour having a curved shape with a convex shape from the middle to the stepped side wall. It is principal part sectional front view which shows another modification of this invention, (A) shows the outline where the uppermost part of the stepped side wall became the concave-shaped curved surface shape, (B) is the lowest part of the stepped side wall Indicates a contour having a concave curved surface. It is a head top view of a screw showing a conventional example. It is an expanded sectional view which shows the action state of a driver bit and the drive hole of a prior art example. It is a plane photograph which shows the head after the screw fastening of a prior art example. It is a cross-sectional top view which shows the relationship with the driver bit of another prior art example.

Hereinafter, the best mode of the present invention will be described with reference to FIGS. In FIGS. 1 and 2 showing the first embodiment, reference numeral 1 denotes a screw comprising a head 3 having a cross-shaped drive hole 2 and a leg 4 formed integrally with the head 3. 4 is formed with a thread 5 along its outer periphery. The screw thread 5 is screwed into a pilot hole (not shown) of a workpiece (not shown) by transmitting a driving force from a driver bit 30 to a driving hole 2 formed at the center of the head 3. It is configured. This drive hole 2 is basically JIS standard and its dimensions are set from No. 0 to No. 4 depending on the size of the screw 1 (nominal dimension), and the number of the drive hole 2 is determined by this number. .

The drive hole 2 has an engaging groove 10 extending in the cross direction from the center. The engaging groove 10 is formed with a stepped side wall 20 having a wide side wall interval (L) on the head surface side. Yes. As shown in FIG. 2, the stepped side wall 20 has a chamfered portion 21 having an inclined shape of about 45 ° at the uppermost portion, and a first portion parallel to the engaging side wall 11 defined in the JIS standard at the lower portion. The wall surface 22 is formed at the bottom with second wall surfaces 23 inclined at substantially the same angle as the chamfered portion 21. The stepped side wall 20 sandwiches the bottom surface 12 of the engagement groove 10 that reaches the deepest portion located at the center of the drive hole 2, and is a normal, that is, cross-shaped engagement groove 10 defined in the JIS standard. The stepped side wall 20 extends from the head surface side to the depth direction of the engaging groove 10 and extends to the planar engaging side wall 11 having the same width as that of the engaging side wall 11. Only a slight depth is formed. Specifically, the depth of the stepped side wall 20 is preferably 10% or less with respect to the nominal size of the screw 1, and the larger the nominal size of the screw 1, the smaller the ratio to the nominal size of the screw 1. It is desirable to do.

As shown in FIG. 3, the engagement groove 10 constituting the drive hole 2 formed in this way is formed on the head surface side with respect to the distance between the intersection of the extension surface of the engagement wall surface 11 and the head surface. The side wall interval (L) is wide, specifically, the interval is wider than the thickness of the engagement blade 31 of the driver bit 30 engaged therewith. By doing so, the engagement side wall 11 contacts the engagement blade 31 of the driver bit 30, but the stepped side wall 20 does not contact the engagement blade 31 when the driver bit 30 is screwed. It has become.

Further, as shown in FIG. 4, the head surface including the drive hole 2 formed in the shape of the engagement groove having the stepped side wall 20 is coated in accordance with a product (not shown) assembled by the screw 1. The paint (A) having a color is applied by a predetermined thickness set in advance, and the paint (A) hardly adheres to the drive hole 2 as the drive hole 2 becomes deeper. This is caused by spraying and painting with a large number of screws 1 with the head 3 facing up, and the coating thickness on the side wall of the drive hole 2 on which the driver bit 30 acts is as described above. The engagement side wall 11 has a configuration that is less than the set thickness and is hardly painted.

In such a configuration, when the driver bit 30 is engaged with the drive hole 2 of the screw 1 and screwed and driven, the engagement blade 31 of the driver bit 30 is engaged with the engagement side wall of the engagement groove 10 as shown in FIG. 11 starts to tighten. At this time, the engagement blade 31 is not in contact with the stepped side wall 20 of the engagement groove 10. In this state, the screw tightening force acts on the engagement side wall 11 and the screw 1 is tightened to the work. When the screw tightening torque reaches a preset torque, the screw tightening operation is finished.

At the end of the screw tightening operation, the engaging groove 10 is slightly deformed, but the amount of deformation is absorbed by the stepped side wall 20 and, as shown in FIG. It will not occur. On the other hand, the coating is applied in the vicinity of the head surface of the drive hole 2, but the interior of the drive hole 2 is hard to be painted, so that the engagement blade 31 of the driver bit 30 acts. The side wall 11 is only slightly painted. Therefore, the coating is prevented from rising to the surface of the head or peeling off.

In addition, the head 3 of the screw 1 having the shape of the drive hole of the present invention and the head of the screw having the conventional drive hole are each coated, and the presence or absence of paint peeling after these are fastened to the workpiece is measured according to the following measurement conditions. And visually inspected. The measurement conditions were as follows: the screw tightening torque was 0.20 N · m, the rotation speed was 1000 rpm, the nominal diameter of the tapping screw was M1.7, the leg length was 3.5 mm, the workpiece thickness was 1.2 mm, and the pilot hole diameter was 1. As a result of a 55 mm cold-rolled steel plate (SPCC steel plate) and screw tightening operation under these conditions, in the screw 1 having the drive hole 2 of the present invention, paint peeling occurred in 30 screw tightening samples. Although the number of the screws was zero, in the conventional screw having the driving hole, the number of the samples that were peeled out of the thirty screw tightening samples was thirteen. Thereby, it was revealed that the present invention is superior.

Further, FIG. 6 shows a second embodiment in which the shape of the stepped side wall 20 of the engagement groove 10 constituting the drive hole 2 of the first embodiment is changed. This is the shape of the chamfered portion 21 and the second wall surface 23. Is the same as that of the first embodiment, but the drive hole 2 in FIG. 6 is changed to a first wall surface 22 constituting the stepped side wall 20 of the engagement groove 10 in the first embodiment, and this surface is used as the axis of the screw. The parallel first wall surface 22 is used.

7 and 8 show a modified example of the stepped side wall 20 of the engagement groove according to the present invention, and FIG. 7 (a) shows a chamfer constituting the stepped side wall 20 of the engagement groove 10 in the second embodiment. The portion 21 to the second wall surface 23 are formed into one concave curved surface shape with an arbitrary radius (R1). FIG. 7 (b) shows the stepped side wall 20 of the engagement groove 10 in the second embodiment. The first wall surface 22 and the second wall surface 23 to be formed into one concave curved surface shape with an arbitrary radius (R2), and FIG. 7 (c) is a stepped side wall of the engaging groove 10 in the second embodiment. The chamfered portion 21 and the first wall surface 22 constituting 20 are formed into one convex curved surface shape with an arbitrary radius (R3).

Further, FIG. 8 (a) shows a chamfered portion 21 constituting the stepped side wall 20 of the engagement groove 10 in the second embodiment having a concave curved surface with an arbitrary radius (R4). The second wall surface 23 constituting the stepped side wall 20 of the engagement groove 10 in the second embodiment is a concave curved surface with an arbitrary radius (R5).

In addition, in these 2nd Example and modification, although the wall of the stepped side wall 20 which comprises the engagement groove | channel 10 is changed into linear form, a concave shape, or a convex curved surface shape suitably, in these Examples and modification examples, In addition to the shape shown, the concave shape can be changed to a convex curved shape, and the interval (L) between the stepped side walls 30 reaching the head surface of the screw 1 is defined in the JIS standard. The shape is not particularly limited as long as it is wider than the width of the head surface of the groove 10.

The present invention is particularly suitable for the screw 1 in which the surface of the head is coated. However, the present invention is not limited to this, and the head 2 of the screw 1 having a normal cross-hole shape that is not painted. Even when used as the drive hole 2 formed in the above, by adopting this shape, it is suitable to prevent slight deformation of the head surface after screwing to the workpiece.

DESCRIPTION OF SYMBOLS 1 Screw 2 Drive hole 3 Head 4 Leg 5 Screw thread 10 Engagement groove 11 Engagement side wall 12 Bottom surface 20 Stepped side wall 21 Chamfered part 22 1st wall surface 23 2nd wall surface 30 Driver bit 31 Engagement blade A Paint

Claims

In the screw part having the cross-shaped drive hole (2) with which the cross-shaped driver bit (30) is engaged, the head surface side of both side walls constituting the engaging groove (10) extending in the cross direction from the center The stepped side wall (20) having a wide gap (L) on the surface side is formed on the bottom surface of the engagement groove, while the flat engagement sidewall has the same width as that of a normal cross-shaped engagement groove on the bottom surface side of the engagement groove. A screw hole drive hole characterized in that a drive hole having a configuration in which (11) is formed and the stepped side wall and the planar engagement side wall are integrally connected is formed.
2. The screw hole drive hole according to claim 1, wherein the stepped side wall is a straight flat surface in a part or all of the stepped side wall.
2. The screw hole drive hole according to claim 1, wherein the stepped side wall has a shape in which a part or all of the cross section thereof is formed into a curved shape.