JPS6340544Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a lock bit consisting of a button bit having a plurality of button-shaped inserts made of a hard material such as cemented carbide.

In general, various types of rock drills are in use, which are the driving parts when drilling into rock using a bit, but all rock drills have the functions of both striking force and rotational force. ing. Among them, the most historical and common type is the rifle bar type.

This has the function of applying rotational force to the rod as the piston of the rock drill moves forward and strikes the shank end of the drilling rod, and then the piston retreats.

In other words, the back-and-forth movement of the piston that generates the impact force also generates rotational force.
Therefore, regarding the blade of the bit attached to the tip of the drilling rod, after the blade penetrates into the rock mass due to the impact force of the rock drill and fractures the rock directly under the blade, the repulsion causes it to separate from the rock surface. In principle, no torque acts on the bit's blade because rotation is applied at the moment the bit is rotated.

However, recent high-efficiency rock drills such as hydraulic rock drills have a different rotation mechanism than the aforementioned rifle bar type rock drill, and they also have a so-called feed force that presses the bit against the rock, and a The rotational force that rotates it has also been significantly increased.

The mechanisms for applying the above-mentioned impact force and rotational force are completely independent; strictly speaking, even when the bit blade is penetrating into the rock mass due to the impact force, the rotational force is acting.

Furthermore, since the feed force is also strong, torque acts on the cutting edge of the bit in order to suppress the repulsion from the rock caused by the impact force and give rotation without the cutting edge of the bit separating sufficiently from the rock surface. .

Therefore, not only impact force but also bending stress due to rotational force acts on the implanted blades, which has the disadvantage that accidents such as breakage of the button-shaped implanted blades may occur.

Figures 1 to 2 are a cross-sectional view and a plan view showing the conventional button bit described above, in which the outermost button-shaped implanted blade b is attached to the head part a of the bit and extends outward with respect to the longitudinal axis c of the bit. It is planted at an angle. This is because the outermost button-shaped implant blade is arranged to determine the outer diameter of the hole to be drilled, and the load applied to the button-shaped implant blade b is not only the load P (y) parallel to the vertical axis c. , P(x) from the lateral direction also acts, so it is inclined to withstand it, and it is well known that this angle of inclination is generally 30 to 35 degrees. On the other hand, the outermost button-shaped implant blade b is the second
As shown, it is inclined outwardly with respect to the longitudinal axis c, but both radial directions are implanted in a diametric direction d passing through the central axis c of the bit.

In such an arrangement of the button-shaped blades b, the direction of the load applied from the rock to the button-shaped blades b due to impact force is substantially the same in the axial direction of the button-shaped blades, and is a compressive force.

Cemented carbide, which is commonly used for the above-mentioned button-shaped inserts, is weak against tensile force but strong against compressive force. Therefore, it is generally desirable to use it in a compression area, and the current arrangement of button-shaped blades is sufficient if only the impact force from the rock drill is considered.

However, as mentioned above, in recent high-efficiency rock drilling machines, rotational torque is also acting on the button-shaped implanted blade, and it can be seen that bending stress is generated accordingly. However, the breakage position of the button-shaped implanted blade is concentrated near the surface of the bit base metal, and since the part embedded in the base metal can be regarded as a rigid body, the above-mentioned breakage position is exactly the location where the bending stress is maximum. It also agrees with Therefore, not only the impact force but also the bending stress caused by the rotational force acts on the button-shaped implanted blades, resulting in problems such as the possibility of breakage of the button-shaped implanted blades.

The present invention was devised to solve the above-mentioned conventional problems, and provides a locking bit that reduces the possibility of breakage of the button-shaped insert blade and has sufficient durability under any usage conditions.

This invention provides a lock bit in which a button-shaped blade made of cemented carbide is implanted, and a bit holder of the outermost button-shaped blade arranged to determine the outer diameter of a hole to be drilled by the bit. The bit is characterized in that the direction in which the bit is implanted is inclined outward with respect to the longitudinal axis of the bit and in the same direction as the direction of rotation of the bit.

Embodiments according to the present invention are shown in Figures 3 to 4 below.
This will be explained in detail based on the figures.

FIG. 3 is a plan view of the head portion of a lock bit showing an embodiment of the present invention. The head portion a of the lock bit is adapted to rotate in the direction of the arrow. The outermost button-shaped implant blade b planted in the head part a is inclined outward with respect to the longitudinal axis c of the bit and in the same direction as the direction of rotation of the lock bit. As a result, the button-shaped implant blade b receives a compressive force P(y) from the impact of the bit.
The resultant force of this and the bending stress P(x) received from the rotation of the bit is made approximately coincident with the axial direction of the button-shaped insert. Therefore, since the resultant force that coincides with the axial direction acts on the button-shaped implant b, bending stress due to the rotational force applied to the implant blade b can be avoided. Fourth
The figure is a plan view of a lock bit showing a modification of the present invention. The outermost button-shaped implant blade b implanted in the head portion a has the same arrangement as in the above embodiment. In addition, button-shaped implanted blades other than the outermost button-shaped implanted blade e
is inclined in the same direction as the rotation direction. In this embodiment configured as described above, the button-shaped implanted blade e is also inclined in the same direction as the rotation direction, so that the button-shaped implanted blade is even more durable and has greater wear resistance. .

As described above, in the present invention, the button-shaped implant blade installed in the lock bit is inclined outward with respect to the vertical axis, and is also tilted in the same direction as the rotation direction of the lock bit. It is possible to avoid bending stress due to rotational force applied to the shaft. Furthermore, since the button-shaped insert blade is made of cemented carbide, it is possible to obtain a long-life bit.

[Brief explanation of the drawing]

1 and 2 are a sectional view and a plan view of a lock bit showing a conventional embodiment, FIG. 3 is a plan view of a lock bit showing an embodiment according to the present invention, and FIG. 4 is another embodiment according to the present invention. FIG. a...Head part, b...Button-shaped implant, c...
Bit vertical axis.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a lock bit having a button-shaped implant made of cemented carbide, the outermost button is arranged to determine the outer diameter of the hole to be drilled by the bit. A lock bit characterized in that the direction in which the implanted blade is inserted into the bit holder is inclined outward with respect to the longitudinal axis of the bit and in the same direction as the direction of rotation of the bit. (2) Utility model registration claim No. (1) characterized in that the button-shaped implanted blades other than the outermost button-shaped implanted blades are installed in the bit holder with an inclination in the same direction as the rotating direction of the bit. Lock bits as described in section.