JPH038402B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a screw nail and a split mold for die-casting used to manufacture the screw nail.

[Conventional technology]

For example, tapping screw nails are used when fixing various components to non-resilient and fragile materials such as gypsum board and ALC board (hereinafter referred to as gypsum board).

Screw nails that are screwed into gypsum board have a structure where the height of the screw is low and the pitch is short, which will destroy the gypsum board and make it impossible to withstand pulling out. Therefore, screw nails with the optimal structure for gypsum board is required.

As a screw nail for gypsum board as described above, the present applicant proposed in Utility Application No. 59-108423 a tapping screw nail that has excellent pulling resistance for gypsum board.

As shown in FIG. 7, the above-mentioned tapping screw nail has a structure in which a screw 3 is provided on the outer periphery of a shaft 2 having a head 1 at one end, and a drill portion 5 is connected to the other end of the shaft 2. The pitch of No. 3 is larger than the diameter of the shaft 2, and the outer diameter of the screw is set to be more than twice the diameter of the shaft 2.

By the way, if the diameter d of shaft 2 is 3 mmφ, screw pitch P = 4 mm, screw diameter D =
It is formed to 6.5mmφ.

Further, the drill part 5 has a conical tip formed at the tip of the circular shaft, and a concave part 5 in the axial direction of the outer circumferential surface.
The opening edge along the axial direction of the recess becomes the cutting edge, and by pushing and rotating, the cutting edge cuts the plaster board and drills a pilot hole, and the recess 5a is formed into a substantially U-shaped cross section. It becomes a storage space for cutting waste.

The above-mentioned tapping screw uses the drill part 5 at the tip to drill a pilot hole in the gypsum board, and screws the screw 3 into the pilot hole to obtain pull-out strength. In order to obtain strong pull-out strength without loosening for materials with no material, the entire surface of the screw must be in close contact with the gypsum board, and in order to meet this condition, the cross-sectional shape of the screw 3 must be made equal over the entire length. No.

By the way, as general methods for manufacturing screw nails, there are known methods that involve cutting or rolling, and a die-casting method that uses a mold.

First, the cutting method has the advantage of being able to finish the entire length of the screw into a uniform cross-sectional shape, but it is labor intensive, inefficient, and wasteful of materials, making the product extremely expensive. , impractical.

Next, the rolling method requires the production of a die with a complicated shape, and as mentioned above, screw nails in which the diameter of the screw is more than twice the shaft diameter cannot be produced by rolling.

Finally, manufacturing by die casting has the advantage of being able to provide inexpensive products because there is no wastage of materials and mass production is possible, but on the other hand, molding using a mold allows for demolding, so the following As will be described in detail in 2006, the shape of the screw is limited and it is not possible to form a screw with a cross-sectional shape that is uniform in overall length.

[Problem that the invention seeks to solve]

That is, when the molding recess of the mold is made into a completely two-part shape of the screw, at both ends of the screw molding part in each mold, the molding surface of the lower surface at the upper end of the screw and the upper surface at the lower end of the screw. However, the screw engages with the screw in the demolding direction of the mold, making demolding work impossible.

For this reason, in conventional molds, the portion of the screw-forming surface where engagement occurs during demolding is scraped off in a horizontal plane so as to avoid any hindrance to demolding.

When a screw nail is die-cast using such a mold, as shown in FIG. 7, the screw 3 becomes partially thicker at the position where the mold abuts, forming a stepped portion 4. When this screw nail is screwed into a gypsum board, the thick part where the screw enters will scrape off the gypsum board, creating a gap between the screw and the gypsum board, causing looseness and reducing the pull-out strength. be.

This invention was made to solve the above-mentioned problems, and provides a die-cast screw nail for gypsum board with uniform screw thickness over the entire length and excellent pull-out strength, and this screw nail. The purpose is to provide a mold that can be used to die-cast.

[Means for solving problems]

In order to solve the above-mentioned problems, the first invention provides for a first invention to provide two or more parts on the outer circumferential surface of the shaft at opposite positions sandwiching the shaft center.
A triangular inclined plane part that expands toward the screw from the apex located in the center between the screws, and a triangular plane part that slopes upward from the base of this inclined plane part toward the base of the screw. It is molded with a symmetrical arrangement between the screws.

In the second invention, the screw nail forming recess is divided into two on the abutting surface side of the two-split mold, and the abutting surface of both molds is formed with a stepped portion along the outer circumferential radial direction of the screw. An uneven surface is formed with an inclined part that is inclined with respect to the axial direction of the shaft and connects the inner and outer ends of adjacent stepped parts, and the molding surface of the molding recess of the shaft part of both molds is formed on the protruding side of the inclined part. A triangular protrusion is provided at the position.

[Effect]

When the abutted material is injected into the forming recess of the abutting mold, a nail with a screw on the outer peripheral surface of the shaft is formed.

Triangular protrusions are provided on the molding surfaces of the shaft parts of both molds, so these protrusions form triangular flat parts on both outer peripheral surfaces of the shaft part, and the protrusions forming the flat parts are used to remove the molds from both molds. The generation of an engaging portion in the mold direction is eliminated, and a nail with the same cross-sectional shape of the screw over the entire length is produced.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6 of the accompanying drawings.

FIG. 6 shows a screw nail according to the present invention, in which a screw 13 is provided on the outer peripheral surface of a shaft 12 having a head 11 at one end, and a drill portion 14 is connected to the other end of the shaft 12. Note that the conditions and structure of each part of the shaft 12, screw 13, and drill portion 14 are the same as those of the screw nail shown in FIG.

At opposing positions on the outer circumferential surface of the shaft 12 sandwiching the axis, the apex is located at the center between the upper and lower screws, and extends in the axial direction toward the screws, sloping downward, and one end of the base is the root of the screws. A triangular inclined plane part 15 that reaches the bottom of the screw, and a triangular plane part 16 that slopes downward from the bottom of the inclined plane part 15 toward the base of the screw.
It is formed in a symmetrical arrangement between the upper and lower screws. Note that on the head 11 side and the terminal end side of the screw 13, only one set of the inclined plane part 15 and the plane part 16 is formed.

Figures 1 to 5 show the main parts of two split molds for producing the above-mentioned screw nail by die-casting. .
The uneven surface is formed by alternately providing inclined portions 24 which are inclined with respect to the axial direction of the step portions 23 and connect the inner and outer ends of adjacent step portions 23 .

Note that the above-mentioned uneven surface is the range of the screw forming part, and since the abutment part between the head 11 and the drill part 14 does not hinder demolding, it is formed by dividing into two straight planes along the axis, and the abutting part of the head 11 and the drill part 14 is 11 is driver engagement groove 2
5 is molded by a head mold 26 that is removed from the mold in the axial direction.

As mentioned above, when both molds 21 and 21 and the abutting surfaces are uneven surfaces, the part from the center to the tip of the step part 23 and the part from the tip to the center of the slope part 24 are the parts of the screw nail. The position of the protruding side of the inclined portion 24 on the shaft molding surface of the molding recess 22 protrudes toward the mating mold side than the central maximum diameter portion, and this portion engages with the shaft 12 in the mold removal direction. A triangular protrusion 27 is provided as shown in FIG. 2, and this protrusion 27 prevents interference between the shaft 12 and the molds 21, 21 during demolding.

As shown in FIG. 1, the protrusion 27 has a triangular surface 27a that forms the inclined plane part 15 of the screw 13, and a triangular surface 27b that forms the plane part 16.
By forming the inclined plane part 15 and the plane part 16 on the outer surface of the shaft 12,
Eliminates interference in the demolding direction.

In this way, by forming the inclined plane part 15 and the plane part 16 into planes extending in the demolding direction using the protrusion 27 on the outer circumferential surface of the shaft 12, the abutting part in the molding part of the screw 13 can be detached as shown in FIG. The screw 13 can be molded to have a uniform thickness over its entire length as shown in FIG. 6 without causing any hindrance to the mold, and a screw nail with excellent durability and extraction strength can be manufactured using a die.

〔effect〕

As described above, according to the present invention, since the configuration is as described above, there are the following effects.

() At opposite positions sandwiching the shaft center on the outer peripheral surface of the shaft,
A triangular inclined plane part that spreads out toward the screw from the apex located in the center between the screws, and a triangular plane part that slopes upward from the base of this plane part toward the base of the screw. Since the screw nails are formed in a symmetrical arrangement between them, when a screw nail is die-cast using a split mold, the flat part provided on the shaft part eliminates the occurrence of an engaging part between the mold and the screw nail when demolding. Therefore, a screw nail having a cross-sectional shape with a uniform thickness over its entire length can be manufactured using a two-piece mold.

() Since the entire length of the screw has a cross section with uniform thickness, there is no gap at the screw entry part when screwing into a non-shrinkable material such as plasterboard.
The pull-out strength is significantly improved.

() The abutment surfaces of the two-split mold are divided into a stepped portion along the outer diameter direction of the screw, and an inclined portion that is inclined with respect to the axial direction of the shaft and connects the inner and outer ends of the adjacent stepped portions. A triangular protrusion was provided on the protruding side of the inclined part on the shaft molding surface of the molding recess, so that the engagement part between the screw nail and the mold in the demolding direction was prevented by the protrusion. By using two split molds, it is possible to die-cast a screw nail with the same thickness as the total length of the screw.

() It became possible to manufacture nails with the same thickness over the entire length of the screw using a mold, and it became possible to provide nails with excellent pull-out strength at a low cost through mass production.

[Brief explanation of drawings]

Fig. 1 is a front view showing the abutting state of the two split molds, Fig. 2 is a longitudinal sectional view showing the separated state of the same, Fig. 3 is a sectional view taken along the arrow - in Fig. 1,
Figure 4 is a cross-sectional view taken along the arrow - in Figure 1, Figure 5 is a perspective view showing the main parts of the mold, Figure 6 is a front view of a screw nail, and Figure 7 is a screw for plasterboard. It is a front view showing a nail. 11... Head, 12... Shaft, 13... Screw, 14... Drill part, 15... Inclined plane part, 1
6... Flat part, 21... Mold, 22... Molding recess, 23... Step part, 24... Inclined part, 27... Protrusion, 27a, 27b... Triangular surface.

Claims (1)

[Scope of Claims] 1. In a nail having screws on the outer circumferential surface of the shaft, at opposite positions on the outer circumferential surface of the shaft across the axis center, there are formed a shape that spreads from the apex located in the center between the screws toward the screw. A screw nail characterized in that a triangular inclined plane part having a shape of 0.1 mm and a triangular plane part inclined upward from the bottom of the inclined plane part toward the base of the screw are formed in a symmetrical arrangement between the screws. . 2 The molding recess of the screw nail is divided into two parts on the abutting surface side of the two-split mold, and the abutting surfaces of both molds are separated from the stepped part along the outer circumferential direction of the screw and the axial direction of the shaft. A triangular shape is formed on the shaft molding surface of the molding recess in both molds at a position on the protruding side of the slope. Split mold for forming screw nails with protrusions.