JPH0882182A - Ground boring bit - Google Patents

Abstract

PURPOSE: To prevent a chip from coming off a chip fitting round hole during the use thereof. CONSTITUTION: A head 2 is provided to the front end of a shank 1, a plurality of chip fitting round holes 3 are bored in the head 2 in either direction parallel with the ground boring direction or inclined direction, and in a ground boring bit in which force-fit of a chip 5 equipped with a columnar drum 4 into each of the chip fitting round holes 3 is made, a plurality of projected threads 6 extended in the direction of force-fit are formed on the circumference of the drum 4 of the chip 5. The projected threads 6 are cut in the circumferential thickness of each of the chip fitting round holes 3 by force-fit of the chip 5. By the constitution, the area of contact of the circumference of the drum 4 of the chip 5 with the internal circumference of each of the chip fitting round holes 3 is enlarged, and frictional resistance against the slippage of the chip 5 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground boring bit, and more particularly, to a bit which is less likely to come off the tip, the working time for the tip press-fitting can be shortened, and the machining cost of the tip can be reduced.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional technique of a bit for boring ground.
As shown in, the head 102 is provided at the tip of the shank 101 as in the present invention, and the head 102 is oriented parallel to the ground drilling direction.
Head 1 in at least one of the inclined directions
There are some cases in which a plurality of round holes 103 for inserting chips are opened in 02, and a chip 105 having a cylindrical body portion 104 is press-fitted into the round holes for inserting chips 103.

In this prior art, the body portion 1 of the chip 105 is
The peripheral surface of 04 is a simple cylindrical surface with no irregularities. The chips 105 are press-fitted into the chip-fitting round holes 103 by manual driving with a hammer. In this conventional technique, when the chip 105 is press-fitted into the chip fitting round hole 103, there is little room for the chip fitting round hole 103 to expand in the radial direction or the barrel portion 104 of the chip 105 to contract in the radial direction. Therefore, the chip 105 is inserted into the round hole 1 for inserting the chip.
In order to press-fit smoothly into 03 and prevent the tip 105 from coming off during use, the tolerance of each dimension of the hole diameter of the tip fitting round hole 103 and the outer diameter of the body portion 104 of the tip 105 is originally set to 0. It is necessary to set it in the order of 0.01 mm.

However, in the usual milling and cutting,
Since the accuracy of the order of 0.1 mm can only be obtained, the round hole 103 for inserting the chip is actually processed by the ordinary drilling with a coarse accuracy of the order of 0.1 mm, and the chip 10
No. 5 is processed by centerless processing with high accuracy on the order of 0.001 mm. Then, when the chips 105 are press-fitted, a plurality of types of chips 105 having different outer diameters of the body 104 on the order of 0.001 mm are prepared, and an assembling operator inserts the chips 105 into the chip fitting round holes 103, respectively.
Then, the work is proceeded while deciding the excess or deficiency of the pressure input by feeling, and selecting the chips 105 that respectively match the round holes 103 for inserting the chips.

[0005]

The above-mentioned conventional techniques have the following problems. Since the peripheral surface of the body portion 104 of the chip 105 is simply a columnar surface without irregularities, the contact area between the peripheral surface of the body portion 104 of the chip 105 and the inner peripheral surface of the chip fitting round hole 103 is relatively small, Tip 1 for round hole 103 for tip insertion
The sliding friction resistance of 05 is small. Therefore, during the ground boring operation, the tip 105 may be loosened by receiving a reaction force from the ground, and the tip 105 may come off from the tip fitting round hole 103.

In the process of press-fitting the chips 105, each chip fitting round hole 1 is selected from among a plurality of types of chips 105 having different diameters.
Since it is necessary for an operator to assemble a chip 105 that conforms to No. 03, the working time is long and the manufacturing efficiency is low.

[0007] From among a plurality of types of chips 105, one that fits each round hole 103 for inserting chips is selected and used, so that the yield is poor and it is necessary to perform highly accurate centerless processing for processing the chips 105. The processing cost of the chip 105 is high.

An object of the present invention is to provide a ground boring bit which does not easily come off from the chip, can shorten the work time for press-fitting the chip, and can reduce the machining cost of the chip.

[0009]

According to the present invention, as shown in FIG. 1, a head 2 is provided at the tip of a shank 1, and at least one of a direction parallel to the ground drilling direction and an inclined direction. In a bit for ground drilling, in which a plurality of chip insertion round holes 3 are opened in the head 2 and a chip 5 having a cylindrical body 4 is press-fitted into the chip insertion round holes 3,
It is characterized by the following.

That is, a plurality of ridges 6 which are long in the press-fitting direction are formed on the peripheral surface of the body portion 4 of the chip 5, and the ridges 6 are bited into the peripheral wall portion 7 of the chip fitting round hole 3 by press-fitting the chip 5. It is characterized by having been done.

[0011]

In the present invention, as illustrated in FIG. 1 (C), the convex strip 6 bites into the peripheral wall portion 7 of the chip fitting round hole 3 when the chip 5 is press-fitted. 5
Even if each dimensional accuracy is rough, the chip 5 can be smoothly press-fitted into the chip fitting round hole 3, and the chip 5 can be prevented from coming off during use. Therefore, it becomes possible to set the tolerance of each dimension of the chip fitting round hole 3 and the chip 5 with a rough accuracy of the order of 0.1 mm, and the processing of the chip 5 does not require highly accurate centerless processing. Further, it is not necessary to prepare a plurality of types of chips 5 having different diameters,
No need to select.

[0012]

According to the present invention, the following effects are achieved. Since the ridge 6 formed on the peripheral surface of the chip 5 bites into the peripheral wall portion 7 of the chip insertion round hole 3, the peripheral surface of the body portion 4 of the chip 5 and the inner peripheral surface of the chip insertion circular hole 3 come into contact with each other. The area is increased, and the sliding frictional resistance with respect to the chip fitting round hole 3 is increased. Therefore, during the ground boring operation, the tip 5 is unlikely to be loosened even if it receives a reaction force from the ground, and the tip 5 is less likely to come off the tip fitting round hole 3.

In the step of press-fitting the tip 5, it is not necessary to select the tip 5 suitable for the round hole 3 for inserting the tip, so that the working time is shortened and the manufacturing efficiency is high.

Since a single type of chip 5 can be used, the yield is good and the processing accuracy of the chip 5 may be low, so that the processing cost of the chip 5 can be reduced.

[0015]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a ground drilling bit according to an embodiment of the present invention. As shown in FIG. 1A, a head 2 is provided at the tip of a shank 1 in the ground boring bit. A plurality of chip fitting round holes 3 are formed in the head 2 in a direction parallel to the ground drilling direction and in a tilted direction, and a cylindrical body 4 is provided in the chip fitting round hole 3. The tip 5 is press-fitted.

A female screw portion 8 is internally provided in the shank 1. The female screw portion 8 is for connecting the ground drilling bit to the ground drilling rod. The integrated shank 1 and head 2 are forged products of alloy steel, and the chip insertion round hole 3 is formed by milling.

A spherical head portion 9 is formed at the tip end of the body portion 4 of the tip 5, and a taper 10 is formed at the base end portion. The tip 5 is made of cemented carbide obtained by sintering a powdery mixture of tungsten carbide and cobalt. The chip 5 is press-fitted into the chip fitting round hole 3 by manual driving with a hammer.

In this embodiment, in order to prevent the chip 5 from coming off easily, shorten the working time of the chip press-fitting, and reduce the processing cost of the chip 5, a long ridge in the press-fitting direction is formed on the peripheral surface of the body portion 4 of the chip 5. A plurality of 6 are formed, and the projections 6 are made to bite into the peripheral wall portion 7 of the chip fitting round hole 3 by press fitting the chips 5.

According to this structure, even if the dimensional accuracy of the chip fitting round hole 3 and the chip 5 is rough, the chip 5 can be smoothly press-fitted into the chip fitting round hole 3 and the chip 5 is in use. Can be prevented from coming off. Therefore, the tolerance of each dimension of the chip insertion round hole 3 and the chip 5 is 0.1 mm.
It is possible to set with a coarse accuracy of the order of magnitude,
High precision centerless machining is not required for machining the chip 5. Further, it is not necessary to prepare a plurality of types of chips 5 having different diameters, and it is not necessary to select the chips 5. Further, in order to form the ridges 6 on the chip 5, it is only necessary to form the ridges on the molded product of the powdery mixture before sintering, so that the chip 5 can be easily manufactured.

[Brief description of drawings]

1A and 1B are views for explaining a ground boring bit according to an embodiment of the present invention, FIG. 1A is a vertical cross-sectional view, FIG. 1B is an enlarged vertical cross-sectional view of a main portion, and FIG. FIG. 3 is a sectional view taken along line CC of FIG.

2A and 2B are views for explaining a ground drilling bit according to a conventional technique. FIG. 2A is a vertical cross-sectional view, FIG. 2B is an enlarged vertical cross-sectional view of a main part, and FIG. It is the CC sectional view taken on the line of (B).

[Explanation of symbols]

1 ... Shank, 2 ... Head, 3 ... Round hole for inserting chips, 4 ...
Body part, 5 ... Chip, 6 ... Ridges, 7 ... Peripheral part.

Claims (1)

[Claims] 1. A head (2) is provided at the tip of the shank (1),
A plurality of chip insertion round holes (3) are formed in the head (2) in at least one of the parallel direction and the inclined direction with respect to the ground drilling direction, and the chip insertion round holes (3) are formed. In a bit for ground drilling in which a tip (5) having a cylindrical body (4) is press-fitted, a long ridge (6) is formed on the peripheral surface of the body (4) of the tip (5) in the press-fitting direction.
A plurality of ridges (6) were formed, and the ridge (6) was made to bite into the peripheral wall portion (7) of the chip fitting round hole (3) by press fitting the chip (5),
A bit for ground drilling, which is characterized by that.