JPH0337814B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to an improvement in a method for manufacturing an expansion anchor.

<Prior art> Expansion anchors are inserted from the tip side into a mounting hole made in concrete, rock, etc., and can be pulled out by expanding the expansion part 3' provided at the tip of the anchor body 1'. The structure is generally composed of an anchor body 1' and a head (not shown), and the anchor body 1' has a cylindrical shape with a hollow hole 5' tapered at the tip. , and a plurality of expansion pieces 3 are provided at the expansion part 3' at the tip.
1'...31'. The head is attached to the rear end (the fourth
Expanding pieces 31'...3 are press-fitted from the left side of the drawing.
It is a rod-shaped item that serves to spread out 1'.

In order to increase the pull-out strength of the expansion anchor, the outer wall of the expansion part 3' has circumferential strips 4' for biting into and locking into the other side such as concrete.
4' is provided.

Conventionally, the method for manufacturing the anchor body 1' of this expansion anchor is to cut a metal wire, create an approximate outline by cutting, rolling, etc., and then drill the center hole 5' one after another with a plurality of drills. It was made to have a tapered shape.

Then, after rolling the circumferential strips 4'...4' for locking, the vertical grooves 2'...2' for forming the expansion pieces 31'...31' are cut with a cross cutter or the like. Was. (See Figure 4) However, forming a tapered shape by cutting with a drill takes a long time, and there is a limit to increasing productivity. It is difficult to press the head into the anchor body 1' and expand the expansion pieces 31'...3.
The problem was that a large amount of force was required to push it 1' apart.

Therefore, as a solution to these problems, a method has been proposed, for example, in Japanese Patent Application Laid-Open No. 57-47011.

In this method, a hollow hole is forged in the center of a round bar, and the outer periphery of the tip is formed into a round shape with a larger diameter and thicker wall toward the tip, and then this round rod-shaped outer periphery is press-fitted inward. By restoring the outer periphery, the tip side of the hollow hole is formed into a tapered shape with a smaller diameter toward the tip, and then a circumferential groove is formed on the outer periphery, and a vertical groove is formed by cutting with a cutter or the like. The expansion part of the expansion anchor is formed by forming the expansion part of the expansion anchor.

However, in this method, the vertical grooves are created by cutting with a cutter etc. in the final step.
Since cutting is performed after forging, the process is divided and cannot be continuously formed, which poses the problem of not being able to reduce manufacturing costs.

On the other hand, in order to form the vertical grooves by forging using a punch with protrusions instead of cutting, the inner periphery of the expanded portion is formed into a tapered shape with a smaller diameter toward the tip, and the wall thickness increases toward the tip. Therefore, when inserting a punch into the hollow hole of the expansion anchor from the tip side, a large load is applied to the tip of the protrusion of the punch, causing the tip of the protrusion to chip or break. It is said to be difficult to continuously form the open anchor through forging.

<Problems to be Solved by the Invention> The present invention has been proposed in view of the above-mentioned circumstances, and its purpose is to form the vertical groove in the expansion part by forging, and to solve the entire process of the expansion anchor. The objective is to make it possible to continuously form the material by forging.

<Means for Solving the Problems> The present invention solves the above problems by providing a method for manufacturing an expansion anchor having the following features.

The method for manufacturing the expansion anchor of the present invention involves forging the hollow hole 5 and forming the outer periphery on the distal end side so that the diameter and thickness become larger and thicker toward the distal end. A punch 6 is press-fitted and a plurality of vertical grooves 2...2 are forged.

This punch 6 includes a shaft portion inserted along the inner circumferential surface of the hollow hole portion 5, and a plurality of protrusions 61...6 protruding in the radial direction along the axial direction from the outer circumferential wall of the shaft portion.
1, and each of these protrusions 61...61 has an inclined part having a diameter larger than the diameter of the hollow hole part 5 and having a protruding height lower toward the tip.

After forming the vertical grooves 2...2, the outer periphery of the distal end, which is formed to have a larger diameter toward the distal end, is pressed radially inward to narrow the outer periphery of the distal end. Form the shape into a tapered shape.

<Function> In the present invention, after the outer periphery of the tip side is formed so that the diameter becomes larger and the wall thickness becomes larger toward the tip, and before forming the tip shape of the hollow hole portion into a tapered shape, the hollow hole portion is , forge and form multiple vertical grooves using a punch.

At that time, the punch has a shaft portion inserted along the inner circumferential surface of the hollow hole portion, and a plurality of protrusions that protrude in the radial direction along the axial direction from the outer peripheral wall of the shaft portion. In addition, each of these protrusions has a diameter larger than the diameter of the hollow hole, and has an inclined part whose protrusion height decreases toward the tip.

By forming a plurality of vertical grooves in this manner, the entire inclined portion of the protrusion of the punch can sequentially press the inner circumferential surface of the hole to form the vertical grooves.

Therefore, the load applied to the punch ridge when the punch is press-fitted from the tip end side can be borne by the entire inclined portion of the ridge, and the ridge can be easily press-fitted and formed without destroying the ridge. Moreover, it is possible to form a tapered vertical groove along the outer periphery shape, the diameter of which increases toward the tip end, so that the thin wall formed between the outer periphery and the protrusion of the punch can be evenly distributed, as shown in Figure 2b. can do.

Then, by pressing the outer periphery of the distal end, which has a larger diameter toward the distal end, in the radial direction and narrowing the outer periphery of the distal end, the shape of the distal end of the hollow hole in the expanded portion is formed into a tapered shape. The expansion anchor can be manufactured only by a forging process without a cutting process.

This allows continuous processing and allows for low-cost manufacturing.

<Example> FIG. 1 is a process diagram showing an example of the manufacturing method of the present invention, and FIG. 2 is a half-sectional view of an anchor body manufactured by the manufacturing method of the present invention shown in FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the dimensions, shapes, materials, relative positions, etc. of the components described in this example are not intended to limit the scope of this invention to only those, unless otherwise specified. , is merely an illustrative example.

As shown in Fig. 2, the anchor body 1 has a hollow cylindrical shape with an expanded portion 3 at the tip (right side in the figure), and the expanded portion 3 has vertical grooves 2...2 cut at 90° intervals. It is composed of four expansion pieces 31...31.

The vertical grooves 2...2 have protrusions 61 as shown in FIG.
...It is forged with a punch 6 having a diameter of 61,
The expansion pieces 31...31 are thin and connected, but of course they may be completely cut.

A tapered hollow hole portion 5 with a tapered tip portion 51 is provided in the center, and an expanded portion 3
On the outer wall of the building, circumferential strips 4...4 are processed using well-known construction methods such as rolling.

Next, the manufacturing method will be explained based on FIG.

Cut the metal wire A into appropriate dimensions. (Fig. 1a) The cut metal wire A is forged and holes 52, 5 are formed.
3 and the expanded pieces 31...31 in the expanded state are made.
(FIG. 1b) The wall 54 remaining between the holes 52 and 53 is punched out to form a hollow hole portion 5. (FIG. 1c) A punch 6 is press-fitted from the tip side of the hollow hole 5 to form the vertical grooves 2...2.

The expansion pieces 31...31 are closed using a closing means such as a die. (Fig. 1 d) Create the circumferential strips 4...4 of the outer wall of the expanded portion 3 using an appropriate construction method such as cutting or rolling. (Fig. 1e) It is appropriate to manufacture the above steps with a parts former, but it goes without saying that other manufacturing machines may also be used.

Note that the shape of the anchor body other than the expanded portion is not particularly limited to the shape of the present invention, and may be appropriately set depending on the purpose of use.

<Effects of the Invention> As described above in the embodiments, in the present invention, before forming the tip of the hollow hole into a tapered shape, a plurality of vertical grooves are formed in the hollow hole using a punch.

At that time, the punch has a shaft portion inserted along the inner circumferential surface of the hollow hole portion, and a plurality of protrusions that protrude in the radial direction along the axial direction from the outer peripheral wall of the shaft portion. In addition, each of these protrusions should have a diameter larger than the diameter of the hollow hole and a sloping part whose protrusion height decreases toward the tip.

By forming a plurality of vertical grooves in this manner, the entire inclined portion of the protrusion of the punch can sequentially press the inner circumferential surface of the hole to form the vertical grooves.

Therefore, the load applied to the punch ridge when the punch is press-fitted from the tip end side can be borne by the entire inclined portion of the ridge, and the ridge can be easily press-fitted and formed without destroying the ridge. Moreover, it is possible to form a tapered longitudinal groove along the outer periphery shape, the diameter of which increases toward the tip end, making it possible to equalize the thickness formed between the outer periphery and the protrusion of the punch. It can be expanded.

Then, by narrowing the outer periphery on the tip side, the tip of the hollow hole in the expansion part is formed into a tapered shape, making it possible to manufacture the expansion anchor only by a forging process without a cutting process. can.

This allows continuous processing and allows for low-cost manufacturing.

As described above, the manufacturing method of the present invention provides an innovative method for manufacturing an expansion anchor.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an example of the method for manufacturing an anchor body according to the present invention, FIG. 2 is a half-sectional view of the anchor body manufactured by the manufacturing method shown in FIG. 1, and FIG. 3 is a longitudinal groove. FIG. 3 is a perspective view of a processing punch. FIG. 4 is a half-sectional view of an anchor body manufactured by a conventional manufacturing method. 1... Anchor main body, 3... Expanded part, 5... Hollow hole part.

Claims (1)

[Claims] 1. A hollow hole 5 is formed in the axial center, and the hollow hole 5 is formed in a tapered shape with the diameter decreasing toward the tip, and a plurality of vertical holes are formed along the axial direction from the tip surface. In the method of manufacturing an expansion anchor by forming the expansion part 3 by forming the grooves 2...2, the hollow hole part 5 is forged, and the outer periphery on the tip side is made to have a larger diameter and a thicker wall toward the tip. After forming the hollow hole 5, a punch is press-fitted into the tip side of the hollow hole 5 to forge a plurality of vertical grooves 2...2, and this punch is inserted along the inner circumferential surface of the hollow hole 5. It has a shaft portion and a plurality of protrusions that protrude in the radial direction along the axial direction from the outer peripheral wall of the shaft portion,
These protrusions have an inclined part whose diameter is larger than the inner diameter of the hollow hole part 5 and whose protrusion height becomes lower toward the tip, and then the outer periphery of the tip side, which has a larger diameter toward the tip, is moved radially inward. A method of manufacturing an expansion anchor, characterized in that the tip shape of the hollow hole portion 5 in the expansion portion 3 is formed into a tapered shape by compressing the outer periphery of the tip side by pressing.