JPS61192911A - Tapping screw and rolling die thereof - 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 <Industrial Application Field> The present invention relates to improvements in a tapping screw and its rolling die. More specifically, the present invention relates to improvements in concrete tapping screws and rolling dies suitable for fixing structural members such as angles and channel members to concrete structures.

<Prior Art> Today, tapping screws are often used in place of anchors and expansion anchors for structures such as concrete.

For example, the double threaded anchor bolt proposed in Japanese Patent Publication No. 53-43625 is an example of this type of tapping screw for concrete. This anchor bolt includes a guide screw and a tapping screw having two different diameters on the outer periphery of a shaft portion having a sharp pointed head.

Guide screws help ensure proper rotation of the anchor bolt relative to the pre-machined pilot hole. The tapping screw has an outer diameter that gradually decreases from the lower part of the neck to the tip, and is provided with a notch of about 90 degrees. This allows for reliable installation using only the spiral screw threads without damaging the wall surface of the pre-drilled hole in the concrete structure. The wood shavings effectively serve to prevent loosening.

<Problem to be solved by the invention> However, when a large amount of concrete shavings (often in powder form) is generated, it gets clogged between the prepared hole and the shaft, which causes tapping. There is also a problem that the torque required for vlfJ increases. Concrete shavings generated at the tip of the screw are an obstacle to tapping. In particular,
36 This tendency is noticeable with tapping screws that do not have a type in which the outer diameter of the tapping screw is gradually reduced, such as the Z5 anchor bolt, and there is a risk of damaging the wall of the pilot hole drilled in the concrete. There is.

The purpose of the first invention of the present application is to perform tapping on a prepared hole drilled in a concrete structure by performing normal tightening only by rotational movement with a tool, and to achieve a reliable tightening and holding effect. Our goal is to provide self-tapping screws. In particular, it is necessary to provide a self-tapping screw that can reliably deal with concrete shavings generated during tapping, reduce the torque required for tapping and tightening, and that can damage the wall surface of a pilot hole drilled in concrete. fru-0 □An object of the second invention of the present application is to provide a die used for manufacturing the above-mentioned novel tapping screw. Furthermore, in order to simplify the manufacturing process, the present invention attempts to provide a die that can completely process the shaft portion of the screw by rolling the screw in two turns.

Means for Solving Problems> Therefore, in order to achieve the above object, the first invention of the present application includes a head for receiving a tightening tool, a shaft extending from the head, and a shaft. A thread is formed on the outer part of the shank, a tapping part is formed at the tip of the shaft part, and a tip tapered part whose diameter decreases toward the tip is formed at the tip of the tapping part. A plurality of shavings receiving grooves extending in the vertical direction are formed in the tapered part, and these receiving grooves reach the tapping part, and the area between these grooves is used as a land, and at least To provide a tapping screw in which a thread for tapping is formed on a land.

Here, the shavings receiving groove is not necessarily limited to one that extends only in the vertical direction, but also includes one that extends in the vertical direction while drawing a spiral curve or a curve.

Further, the thread may be formed in one thread or in plural threads, and the diameter of the thread may be changed.

A second invention of the present application provides a die for rolling the above-mentioned tapping screw. The upper part of this die is provided with a thread forming part, the lower part of the die is provided with a rubbing part forming part, and the thread forming part has a large number of thread forming grooves formed on a flat surface. A plurality of convex portions for forming shavings catching grooves are formed in the thread forming portion, and these convex portions are juxtaposed to protrude from the flat surface of the thread forming portion, and there are The concave portion is a concave portion for forming a land, and an inclined concave portion that gradually projects toward the convex portion is provided below the concave portion for forming a land, and a tapping screw thread for forming a screw thread for tapping is provided below the concave portion for forming a land. A rolling die 3 for a tapping screw is provided in which a forming groove is provided in at least a concave portion of a topping portion forming portion.

<Function> Accordingly, in the tapping screw of the present invention, concrete shavings generated by tapping escape into the shavings receiving groove and are collected there. As a result, there is no possibility that a large amount of shavings will become stuck between the screw thread and the wall surface of the concrete pilot hole. Moreover, since the thread for tapping is divided by a plurality of shavings catching grooves extending in the vertical direction, it is advantageous for gradually scraping away the wall surface of the concrete prepared hole. The thread forming groove of the rolling die forms the shaft of the screw, and the protrusion at the bottom of the die forms the shavings catching groove.
A land is formed by the concave portion, and a tapping screw thread is formed by the tapping screw thread forming groove of the concave portion, respectively, by rolling in the same process.

<Example> The present invention will be explained in detail below based on the figures.

FIG. 1 shows an overall view of an exemplary self-tapping screw, which has a head (3) with a cross recess (2) for receiving a tightening tool and a head (3) extending from the head; It has a shaft portion (4). This shaft portion (4) has a substantially constant diameter, and a thread (7) is formed on its outer periphery. A tapping portion (51) is provided at the tip of the shaft portion (4), and a tip tapered portion (6) whose diameter decreases is formed at the tip.

As shown in the enlarged view of FIG. 2 and the explanatory view of FIG. 3, a pair of shavings receiving grooves (8) are formed at the tip of the shaft (4). This shavings receiving groove (8) has a tapered tip portion (6
) and ends within the tapping part (5). Then, these reception tlli (8) (the site between 81 is land +9) 191. These lands (91 (
9), a tapping thread fl (I) is wound around the receiving groove (8) in a continuous manner with the thread (7). This tapping thread αα is connected to the tapping part ( The run in 5)" (9) is wound two to three times, and the terminal end (111) of this thread αa ends at the land (9) in the tapered tip part (6).

This land (9) has a second diameter, and its diameter decreases as it moves away from the cutting edge 114 of the receiving groove (8), which will be described later. Along with this, the tapping screw thread (No. 11) also has a second thread.

Here, I would like to mention the diameter of this tapping screw.
The diameter of the land (9) in the tapping part (5) (
a) is slightly larger than the diameter (l) of the shaft portion (4), and the thread diameter of the thread 17 is the same as that of the land (9).
The diameter (&) of the tapping screw thread (1 (
It is slightly larger than or equal to the diameter of l. The diameter of the female thread for tapping (11 is the thread diameter of the thread 1G terminal (111
As it approaches , it decreases and the thread side disappears. In addition, the run at the tapping part (5)" (diameter of 91 (a)
A concrete structure (21
When used against the + pilot hole, the land (9) acts as a guide during tapping and screw tightening, ensuring smooth screw rotation. In addition, the run)'+91 has the second hole, and the entire land (9) does not engage with the pilot hole, so it is possible to prevent an increase in rotational torque or generation of large frictional heat. .

Note that even if the pilot hole of the concrete structure (21) is incomplete, it can be cut by the receiving groove (8) and corrected to a pilot hole of an appropriate diameter. That is, the receiving groove (8)
1 and a drag surface a3, the cutting edge f1 of the cutting surface 021
4i allows the pilot hole to be drilled. However, the names of the cutting surface and the cutting edge α4 are borrowed from the names of trills, and in the present invention, the receiving groove (8) does not necessarily have to exhibit a cutting function.

In addition, in the embodiment, the tip of the tapered portion (6) is sharp,
Although it has an approximately drill shape, the tip does not necessarily have to be sharp, and may have an inverted truncated cone shape without a sharp tip.

Further, the tapping thread 0α is divided by the receiving groove (8), and its end surface protrudes from the cutting edge α of the receiving groove (8). This end surface os is preferably along the vertical plane (B) passing through the axis of the screw, but is not limited to this, and may be at an angle with respect to the vertical plane (G). . By dividing the tapping screw thread (1 (l) by the receiving groove (8), a large number of end faces o... , form a female thread in the pilot hole ■.
Since the thread aα for tapping has a second hole,
During this tapping, only the end face 05 and the relevant thread 101 in the vicinity engage with the wall surface of the pilot hole (■), and the other parts of the relevant thread (10!) do not engage, so the rotational torque required for tapping is reduced. It is possible to reduce the number of screw threads for tapping (the other part with the second hole of 1B is
During tapping, it serves to provide appropriate strength to the end surface αS and its vicinity to support them.

The above tapping screw thread 0α is concrete structure c! 1) Concrete shavings generated by scraping the wall surface of the pilot hole (2) are collected in the receiving groove (8).

This receiving groove (8) is formed from the tip-pa part (6) to the axis of the tapping (5), has a considerable capacity, and can collect a large amount of concrete shavings. If the receiving groove (8) extends vertically in a spiral manner as in the embodiment, the shavings are efficiently discharged through the receiving groove (8). Some of the discharged shavings are
Although it is carried to the outside of the pilot hole (2), a part of it is stuck in the space between the wall surface of the pilot hole (2) and the shaft (4), and serves to increase the reliability of the installation of the tapping screw. Note that this space depends on the difference in diameter between the pilot hole (■) and the shaft (4), but in this example,
As mentioned above, the run in the tapping part (5)'
(The diameter (a) of the portion 91 is the diameter (b) of the shaft portion (4)
), the space is secured by the difference between the two.

4 to 6 show dies for rolling the aforementioned self-tapping screws. However, since FIG. 6 is an enlarged perspective view of the die seen from above to below, it is shown upside down compared to the plan view of FIG. 4.

The upper part of the die is provided with a thread forming part (101), and the lower part of the die is provided with a thread forming part (102).
) is provided.

The thread forming part (101) has a large number of thread forming parts If (104) arranged in parallel at a predetermined lead angle on a flat surface CLO3).

A large number of convex portions (105) for forming shavings catching grooves are arranged in parallel in the tapping portion forming portion (lO2), and a concave portion (lO6) between the convex portions (105) is used for forming a land. In order to form this convex part α05) which becomes a concave part, a bank part (10'7) protruding like a table from the flat surface (103) is formed in advance at the bottom of the die, and this bank part (107) is formed in advance. may be processed by grinding, electrical discharge machining, or the like.

The convex portion (105) and the concave portion (106) extend obliquely at a larger lead angle than the thread forming groove (104). The recess (lO5) has a flat surface (lO5) as shown in FIG.
A substantially parallel concave portion (lO3) extending slightly deeper than
O8) and an inclined recess (110) rising from the bottom of the die toward the top (lO9) of the bank (lO7).

The substantially parallel recess (108) has a tapping thread forming groove (i) extending from the thread forming groove (104) at the same leet angle.
ll) is formed. This tapping thread forming groove (Ill) has almost the same size and depth as the thread forming groove (104), but as shown in FIG. 5, it gradually becomes shallower and disappears as it goes downwards of the die. .

The convex portion (105) includes a substantially parallel convex portion (112) that protrudes from the flat surface (103) and extends at approximately the same height, and a bank portion (
An inclined convex part (113) that further rises near 107)
It consists of This inclined convex part (113) and the inclined recessed part (110) cooperate to form a tip tapered part "6",
In particular, the inclined convex portion α13) forms a receiving groove (8) in the tapered tip portion 16). The substantially parallel convex portion (l), 2) is composed of a cutting surface forming surface (114) and a drag surface forming surface (Z15), and is composed of a cutting surface forming surface (11) and a convex portion (106).
) becomes the cutting edge forming line (116).

In addition, since the run)" (9) is taken at the second position, the recess (10a) forming the land is the cutting edge forming: @ (116
) is deepest near the convex portion, and gradually becomes shallower as it approaches the drag surface forming surface (115) of the convex portion.

By rolling the wire with the thus formed die, the detailed threads of the screw (near) and the tapping part (5),
A tip tapered portion (6) is formed at the same time.

<Effects of the Invention> As described above, in the tapping screw that is the first invention of the present application, when tapping a pilot hole drilled in a concrete structure, the concrete shavings generated by tapping become shavings. Since the shavings escape into the receiving groove and are collected there, there is no risk of large amounts of shavings becoming stuck between the screw thread and the wall of the concrete pilot hole.

Therefore, there is no risk of shavings getting stuck between the screw and the pilot hole, the problem of increased torque required for tapping and mf=J is solved, and the female thread can be screwed without damaging the wall of the pilot hole drilled in concrete. can be formed and tightened.

Moreover, since the thread for tapping is divided by the swarf catching groove, a large number of end faces are formed. The end surface of this tapping screw gradually scrapes the wall surface of the concrete pilot hole. Therefore, a female thread can be accurately formed without damaging the wall surface of the pilot hole.

A second invention of the present application provides a die capable of rolling the above novel tapping screw. Moreover, according to the die of the present invention, the processing of the threaded portion, the tapping portion, and the tapered tip portion can be simultaneously performed in one step.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a tapping screw that is an embodiment of the first invention, Figure 2 is an enlarged perspective view of the main parts of the same screw, Figure 3 is an explanatory diagram of the bottom surface of the screw, and Figure 4 is A front view of a rolling die for a tapping screw according to an embodiment of the second invention, FIG. 5 is an enlarged perspective view of a main part of the die, and FIG. (3)...Head, (4)...Shaft, (5)...Tapping part, (6)...Tip tapered part, (7)...
Thread, (8)...Receiving groove, (9)...Land, (
1... Thread thread for tapping, (101)... Thread forming part, (102)... Tapping part forming part, (l
O3)...Flat surface, (104)...Thread forming groove,
(105)... Convex portion, (l O6)... Concave portion, (1
11)...Tapping thread forming groove.

Claims (1)

[Scope of Claims] 1. Comprising a head for receiving a tightening tool and a shaft extending from the head, a thread is formed on the outer periphery of the shaft, and a tapping portion is formed at the tip of the shaft. At the tip of this tapping portion, a tip tapered portion is formed whose following diameter decreases toward the tip side, and a plurality of shavings receiving grooves extending approximately vertically are formed in the tip tapered portion. A tapping screw in which the receiving groove reaches a tapping part, the area between these grooves is a land, and a thread for tapping is formed on at least the land in the tapping part. 2. The tapping screw according to claim 1, wherein the thread formed on the outer periphery of the shaft portion and the thread for tapping formed on the land are continuous. 3. The tapping screw according to claim 1 or 2, wherein a thread for tapping is formed from a land in the tapping portion to a land in the tapered tip portion. 4. The tapping screw according to claim 1, 2, or 3, wherein the tip of the tapered portion is sharp and has a substantially drill shape. 5. The tapping screw according to claim 1, 2, 3, or 4, wherein at least the land on which the tapping thread is formed is double-bored. 6. The upper part of the die is provided with a thread forming part, the lower part of the die is provided with a tapping part forming part, the thread forming part has a large number of thread forming grooves formed on a flat surface, and the tapping part is provided with a thread forming part. A plurality of convex portions for forming shavings receiving grooves are formed in the forming portion, and these convex portions protrude from the flat surface of the thread forming portion and are arranged in parallel, and a concave portion between these convex portions is formed. is a recessed portion for forming a land, and an inclined recessed portion that gradually projects toward the convex portion is provided below the recessed portion for forming a land, and a tapping thread forming groove for forming a threaded thread for tapping is provided. A rolling die for a tapping screw, which is provided in at least a concave portion of a tapping portion forming portion.