JPS62189293A - Pawl for head of drill - 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 (Field of Industrial Application) The present invention relates to a pawl attached to the head of an earth auger drill, and more specifically, the present invention relates to a pawl that is attached to the head of an earth auger drill, and more specifically, a pawl that is designed in consideration of wear resistance and ease of manufacture. Concerning shape.

(Prior art) Figure 6 shows the earthener P with the conventional claws LA and IB attached.
To i do 11 le, -, ): There is a difference, hera 1 - tun 1
Two screw plates 3A and 3B are welded to 1 (casing) 2, and one or more pawls LA and IB (two in the illustrated example) are arranged in the inner and outer directions at the lower ends of these screw plates 3A and 3B, respectively. and then welded. These nails LA, IB
has a prismatic shape, as shown in FIGS. 7 and 8,
Cemented carbide is overlaid or brazed on the sharply formed tip 1a and the outer surface 1b, and the tip 1a has an inclined surface 1c formed on its upper surface so as to gradually become narrower.

In such a conventional structure, as shown in FIG.
Since the tip of the outer claw IA protrudes outward from the rotation locus 4 of the outer surface 1b as the drill rotates, as shown in FIG. As shown in the shaded area 5, it wears out in a triangular shape.
Every 2 to 3 months, the head must be carried from the field to the factory, the old pawl IA must be cut off from the screw plates 3A and 3B, and the new pawl IA must be welded to the screw plates 3A and 3B. There are problems in that they need to be replaced frequently and are uneconomical because they are expensive and use a lot of cemented carbide.

Therefore, the present inventor has proposed Utility Application No. 59-2813, Utility Application No.
As proposed in No. 9-25178 and Utility Model Application No. 59-:10077, the shape of the claws 6A and 6B can be changed to an arc shape along the rotation locus 4 shown in FIG. We have already developed something that is shaped like this.

With this shape, as the usage period passes, the claw 6A will wear from the outer surface 6a, and the degree of wear of the tip 6b, which plays the role of biting during hole drilling, will decrease, reducing the wear. Experiments have shown that when this structure is adopted, the lifespan can be extended by about four times compared to conventional methods.

However, if these claws are made to have a simple square or rectangular cross-sectional shape when cut in the transverse direction, it is difficult to form them without casting, and if by forging, a complex mold with a composite shape is required. It cannot be molded without it.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned points, and it is possible to reduce the wear of the tip over the period of use, reduce the frequency of replacement, and make it easier and cheaper. The purpose of the present invention is to provide a manufacturable drill head claw.

(Means for Solving the Problems) In the present invention, the shape of the claw is formed into an arcuate shape along the rotation locus accompanying the rotation of the drill on the outer surface of the claw, and a twisted shape, and the shape is short. The cross-sectional shape cut in the hand direction is
It is characterized by being formed in a tapered shape that becomes narrower toward the bottom.

(Function) If the claw is shaped like this, die cutting can be easily performed when forging is used, and the claw can be manufactured by forging using a mold having a simple shape.

(Example) Figures 1 and 2 show an embodiment of the claw of the present invention. As shown in the figures, the cross-sectional shape of the claw when cut in the transverse direction is tapered so that the width becomes narrower toward the bottom. It is formed into a shape. Further, as shown in FIG. 3, the overall shape of the claw 8 in this embodiment is not only curved in an arc along the side surface 7A of the excavated hole, but also has a sharp tip. It has a twisted shape so that the inner side 8b of 8a is slightly lowered.

As mentioned above, if the claw 8 is shaped so that its bottom is narrow, then as shown in FIG.
The claw material 8A is formed by forging, in which the material is set between a lower die 10 having a diameter 0a and an upper die 9 having a recess 9a corresponding to the shape of the claw material 8A, and is compressed or struck with a hammer. Thereafter, the upper mold 9 can be removed together with the material 8A from the lower mold 1O, and the burr 8e can be taken out by hanging it on a hook (not shown) and pulling it out from the recess 9a of the upper mold 9. The extracted material 8A is
The peripheral burr 8e is removed and cemented carbide is welded to necessary parts such as the tip 8a and the upper corner of the outer surface 8 to produce a product.

Further, in this embodiment, since the pawl 8 has a twisted shape, the pawl can be inserted into the screw plate 3 as shown in FIG.
When attached to the lower end of A (3B) by welding, the tip 8a of the claw 8 can be made horizontal, so that the tip 8a of the claw 8 is completely flat against the bottom surface 7 of the excavated hole. The screw plate 3A (
3B), the outer surface 8C of the claw 8 is vertical over its entire length, as shown in FIG.
If a claw with a rectangular cross section is simply curved into an arc, when it is attached to the screw plate 3A (3B), that is, when the tip is tilted downward, the outer surface of the claw will be
Since the upper part of the tip of the claw protrudes outward), the entire outer surface comes into contact with the wall surface 7A of the excavation hole, so there is a phenomenon in which the outer upper part of the tip 8a wears out, as if it were simply curved into an arc. It is also possible to prevent the occurrence of According to experiments, the structure of this embodiment has been shown to maintain a lifespan 10 to 20 times longer than that of conventional claws.

When carrying out the present invention, there are various twisting structures. For example, it is possible to form three or more discontinuous surfaces on the upper and lower surfaces of the nail so that the entire nail is twisted.

(Effects of the Invention) According to the present invention, the wear of the tip over the period of use is reduced, there is no wastage of material, an economical claw can be realized, and the frequency of replacement of the claw can be reduced. , it is possible to provide nails that are extremely useful to the user.

Furthermore, unlike casting, the claw of the present invention does not require a large-scale heating device or heating time for materials, and can be manufactured easily and inexpensively by forging using a simple die.

[Brief explanation of drawings]

Figures 1 (A), (B), and (C) are a side view, a plan view, and a front view showing one embodiment of the claw of the present invention, respectively, and Figure 2 (
A), (B), and (C) are E-E in Figure 1 (B), respectively.
, F-F, GG sectional views, FIG. 3 is a front view showing the claw of this embodiment in the installed state, FIG. 4 is a sectional view showing the molding method of this embodiment, and FIG. FIG. 6 is a front view showing the head with the conventional claw attached, FIG. 7 is a perspective view showing the outer claw, and FIG. 8 is a view similar to the one shown in FIG. 6. FIG. 9 is a plan view illustrating the problems of the conventional claw. 2...Head shaft, 3A, 3B-...Screw plate, 4
... Rotation trajectory, 8... Claw

Claims (1)

[Claims] In the claw attached to the head of the earth auger drill, the shape of the claw is such that the outer surface of the claw has an arc shape along the rotation locus accompanying the rotation of the drill, and is twisted in the transverse direction. A claw for a drill head, characterized in that the cut cross-sectional shape is tapered so that the width becomes narrower toward the bottom.