JPH0133632B2 - - Google Patents

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 particularly to a pawl shape that takes wear resistance into consideration.

(Prior Art) Fig. 1 is a diagram showing a conventional earth auger drill head with claws 1A and 1B attached to the head shaft 2.
Two screw plates 3A and 3B are welded to the bottom edge of each screw plate 3A and 3B.
At least two pawls 1A and 1B (two in the illustrated example) are arranged and welded in the inner and outer directions. these nails 1
A, 1B are as shown in FIGS. 2 and 3,
Cemented carbide is welded or brazed onto the tip 1a and the outer surface 1b, which are prismatic and sharp, and the tip 1a has an inclined surface 1c formed on the upper surface so as to gradually become narrower. There is.

In such a conventional structure, as shown in FIG. 3, the tip of the outer claw 1A protrudes outward from the rotation locus 4 of the outer surface 1b as the drill rotates. As the head is used, the outer part of the tip 1a wears out in a triangular shape as shown by the shaded area 5, and every 2 to 3 months the head is transported from the site to the factory to remove the old nail 1A. The screw plates 3A and 3B have to be melt-cut and new claws 1A are welded to the screw plates 3A and 3B. This requires replacement frequently and is expensive as it uses a lot of cemented carbide. The problem is that it is uneconomical.

Therefore, as shown in FIG.
We have already developed and proposed shapes of A and 6B in which both the inner and outer surfaces or the outer surface form an arc shape along the rotation locus 4 shown in FIG. No. 2813). 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.

(Problems to be Solved by the Invention) However, in the case of a claw with this structure, in which the inner and outer surfaces are simply formed in an arc shape, it is difficult to see the bottom surface of the excavated hole in the actually installed state, that is, as shown in FIG. When welded to the lower end of the screw plate 3A (3B) so as to be inclined with respect to 7,
As shown in FIG. 7, when viewed from the front of the claw, the inner side 6c of the tip 6b of the claw is h larger than the outer side 6d.
It will be in a state where it has risen by the height shown by , and therefore,
The tip of the claw dug into the bottom of the excavation hole from the outside, and although it was not as bad as the conventional claw, it still caused the phenomenon that the tip of the claw wore out from the outside. In addition, when the claw 6 is attached to the screw plate, as shown in FIG.
protrudes outward from the bottom, and the upper outer part of the claw tip 6a tends to wear out easily.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned points, and the present invention has been made in view of the above-mentioned points. The outside surface of the nail is arcuate along the entire length along the rotation locus as the drill rotates, is a vertical surface, and is twisted so that the tip of the claw is horizontal.

(Example) As shown in the example diagram of FIG. 8, the claw of the present invention is manufactured, for example, by forging (in addition to forging, the claw of the present invention can also be manufactured by casting).
The material having a rectangular cross section is not simply bent into an arc shape along the side surface 7A of the excavated hole, but is twisted so that the inner side 8b of the tip 8a of the sharply formed claw 8 is slightly lowered. As shown in FIG. 9, the claw is attached to the screw plate 3A (3B)
When attached by welding to the lower end of the claw 8, the tip 8a of the claw 8 is horizontal.

With such a structure, the tip 8a of the claw 8 can be completely wedged into the bottom surface 7 of the excavated hole, preventing wear from concentrating on the outside of the tip 8a, and further improving the installation process. In this state, both the outer surface 8c and the inner surface 8d are vertical surfaces over the entire length, so the entire outer surface contacts the wall surface 7A of the excavation hole. It is also possible to prevent the phenomenon of wear. According to experiments, compared to traditional nails,
It was possible to maintain a lifespan of 10 to 20 times longer.

FIG. 10 shows another embodiment of the present invention, in which the distal end 9A is twisted from the middle part of the claw 9 so that the distal end 9a becomes horizontal in the attached state. In addition, the attachment end side of the claw may be twisted, or three or more discontinuous surfaces may be formed on the upper and lower surfaces of the claw so that the entire structure is twisted. Further, as shown in FIG. 11, a reinforcing plate 10 is welded to the back side of the screw plate 3A (3B), and the reinforcing plate 10 and the screw plate 3A (3B) are connected together.
It is also possible to weld the claws 11 thereto. Furthermore, as a means for attaching the claws to the screw plate 3A (3B), bolting can be used in addition to welding and brazing.

(Effects of the Present Invention) According to the present invention, the shape of the claw is formed such that in the attached state, the outer surface of the claw forms an arc shape along the rotation locus accompanying the rotation of the drill. Prevents uneven wear on the front and back of the
In addition, since the outer surface of the claw is vertical, it is possible to prevent uneven wear in the vertical direction of the claw, and since the tip of the claw is formed horizontally, it is also possible to prevent uneven wear on the tip of the claw. This makes it possible to extend the life of the nail far more than that of conventional nails, significantly reduce the frequency of replacement, and eliminate waste of materials, making it possible to realize an economical nail. In addition, when a claw formed in the shape of the present invention is used in the head at the lower end of the drill, it becomes possible to excavate rock, which was difficult to do in the past.
It has been confirmed that rock excavation can be performed with twice the efficiency.

[Brief explanation of drawings]

Fig. 1 is a front view showing the head with a conventional claw attached, Fig. 2 is a perspective view showing the outer claw, Fig. 3 is a partial plan sectional view of Fig. 1, and Fig. 4 is a conventional claw. 5 is a perspective view showing the claw previously developed by the present inventor, and FIGS. 6 and 7 are side views of the claw in the attached state and illustrating the respective problems. A front view, FIGS. 8A, B, and C are a side view, a plan view, and a front view showing an embodiment of the claw of the present invention, respectively, and FIG. 9 is a front view showing the claw of the embodiment in an installed state. 10 is a perspective view showing another embodiment of the invention, and FIG. 11 is a side view showing still another embodiment of the invention. 2... Head shaft, 3A, 3B... Screw plate, 4... Rotation locus, 5... Worn part, 8, 9,
11... Claw, 8a, 9a... Tip, 10... Reinforcement plate.

Claims (1)

[Claims] 1. Regarding the claws attached to the head of the earth auger drill, the shape of the claws shall be such that, when the claws are installed, the outer surface of the claws has an arc shape along the entire length along the rotation locus accompanying the rotation of the drill, and has a vertical surface. A claw for a drill head of an earth auger characterized by being formed in a twisted shape so that the tip of the claw is horizontal.