JP3246418B2 - Round pick - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a round pick for excavating a workpiece by being attached to various excavating tools.

[0002]

2. Description of the Related Art Conventionally, as this kind of round pick, the one shown in FIG. 2 is generally known. In this round pick, a substantially multi-stage cylindrical head portion 2 whose diameter is reduced toward the front end side is provided at a front end portion of the round pick main body 1, and a head portion 2 is provided at a rear end portion of the round pick main body 1. A cylindrical shaft-shaped shank portion 3 having a smaller diameter than that of the head portion 2 is provided. A tip of the head portion 2 is formed in a truncated cone shape whose diameter is reduced toward the tip side. A tip 4 made of cemented carbide is implanted so as to protrude. However, the round pick configured in this manner is used for the tool body of various excavating tools such as a cylindrical rotary drum of a road surface excavating vehicle, an auger screw of an earth auger, or a drum of a wing or a road header of a shield excavator, Shank part 3 above
Is embedded so that the head portion 2 is protruded, and the tip 4 excavates a road surface or ground with the rotation of the tool body.

[0003]

By the way, in such a round pick which is attached to the tool body of the excavating tool and is used for excavation, the tip 4 or 4 which projects from the tool body and cuts into the road surface or the ground. The excavation load acting on the tip of the head portion 2 around the tip is remarkable. In particular, since the tip 4 is made of cemented carbide, the round pick body 1 is usually made of structural steel such as SCM material. There is a problem that the tip of the head portion 2 is worn by the excavation load, which causes the tip 4 to fall off and shorten its life. However, in this regard,
In the conventional round pick, the progress of abrasion is suppressed by hardening the surface of the head portion 2 by applying a hardened overlay, for example, but the hardened overlay tends to peel off, and a large excavation load is imposed. It was not tolerable for long-term use under working conditions.

The present invention has been made under such a background, and even under a condition where a large excavation load is applied, it is possible to suppress the wear of the head portion, and thereby a round pick which can withstand long-term use is provided. It is intended to provide.

[0005]

Means for Solving the Problems In order to solve the above problems and to achieve such an object, the present invention provides a round pick body having a head portion provided with a tip at a tip end thereof, In a round pick in which a shaft-shaped shank portion is provided at a rear end of the round pick main body, the head portion has a large diameter from the rear end toward the front end.
And a circle connected to this disk via a concave arc surface
A cylindrical part with a smaller diameter than the plate part, and the tip of this cylindrical part
And the frusto-conical part, which gradually decreases in diameter toward
With a conjugated shape, circular said round pick body, perpendicular to the central axis of the round pick body
The head has a joint surface on the rear end side of the cylindrical portion of the head.
In this case, the front end side is formed of tool steel, and the rear end side is formed of structural steel. Therefore, according to the round pick having such a configuration, since the periphery of the tip on the tip side of the round pick main body is formed of tool steel having high hardness, the wear resistance is improved and a large excavation load is applied. However, it is possible to prevent chips from falling off, but it is more economical than, for example, a case where the whole round pick body is formed of tool steel.

Here, in order to form the front and rear ends of the round pick body with different materials in this manner, the round pick body is formed by a tool steel head member forming the front end side of the head portion. And the structural steel shank member forming the shank portion and the rear end side of the head portion may be joined by friction welding. In particular, as described above, the round pick body is provided between the head portions. By dividing the head member into a head member and a shank member made of different materials and joining them together, the joint area can be secured, so that sufficient joining strength can be obtained. Also, the hardness of at least the periphery of the tip of the head portion of the round pick body formed of tool steel is desirably _HRC 50 or more. If the hardness is lower than this, wear resistance when a large excavation load is applied is reduced. There is a possibility that the properties may be insufficient.

[0007]

FIG. 1 shows an embodiment of the present invention. The round pick of the present embodiment also has a round pick body 1 similar to the above-described conventional round pick.
A substantially multi-stage cylindrical head portion 12 whose diameter is reduced toward the front end side is provided at the front end of the round pick main body 11, and the rear end of the round pick main body 11 has a cylindrical shaft shape smaller in diameter than the head portion 12. The shank 13 is provided, and the tip 14 is embedded at the tip of the head 12 so as to protrude. Here, the head 12
Is a large-diameter disk portion 12A from the rear end side to the front end side.
A cylindrical portion 12C having a smaller diameter than the disk portion 12A connected to the disk portion 12A via the concave arc surface portion 12B, and a truncated conical portion 12D whose diameter gradually decreases from the distal end to the distal end side of the cylindrical portion 12C. Has a coaxially integrated shape, and a concave portion 12E having a circular cross section to which the tip 14 is attached is formed on the distal end surface of the truncated cone portion 12D, that is, on the distal end surface of the head portion 12. .

The tip 14 is formed of a hard material such as a cemented carbide, and is provided with a substantially conical cutting edge 14B at the tip of a cylindrical body 14A.
A is attached to the tip of the head section 12 by inserting and brazing A into the recess 12E. On the other hand, the shank portion 13 has an outer diameter that is substantially the same as the distal end surface of the truncated cone portion 12D of the head portion 12, and an annular groove 13A is formed on the outer peripheral surface on the rear end side. The shank portion 13 is formed integrally with the rear end of the head portion 12 such that the central axes of the head portion 12, shank portion 13, and chip 14 are coaxial with each other. It is planted and arranged in.

In the round pick body 11 of the present embodiment having such a shape, the front end of the head portion 12 is formed of tool steel such as carbon tool steel or alloy tool steel, and the rear end of the head 12 is formed from the tool steel. The shank portion 13 is formed of structural steel. That is, in the present embodiment, the round pick main body 11 is constituted by two members 15 and 16 having a joint surface P on the rear end side of the cylindrical portion 12C of the head portion 12, and the front end side head The member 15 is made of tool steel (alloy tool steel) such as SKD11 and the shank member 16 on the rear end side is made of SCM440, SCM435, or SN.
It is made of structural steel such as CM material.

Further, in the present embodiment, the joint surface P between the head member 15 and the shank member 16 is a plane orthogonal to the central axis of the round pick body 11, that is, the head portion 12, the shank portion 13, and the tip. 14
The head member 15 and the shank member 1 are formed as a plane (circular surface) orthogonal to the central axis of
6 are joined to each other by abutting the joining surfaces P and friction-welding. In addition, since the head member 15 is formed of tool steel and the shank member 16 is formed of structural steel as described above,
In this embodiment, the round pick to the bonding surface hardness of the rear end side of the P body 11 in the range of about H _RC 36-40, which from the distal side of the tip 14 near the hardness H _RC
50 or more, would be set to about H _RC 58-62 more specifically.

Therefore, according to the round pick constructed as described above, since the tip side of the round pick main body 11 is formed of high hardness tool steel, the excavation conditions under which a large excavation load acts for a long period of time. In this case, the tip 14 can be reliably held by suppressing wear of the tip of the round pick body 11 due to earth and sand, thereby preventing the tip 14 from dropping off early and extending the life of the round pick. Becomes possible. On the other hand, the rear end side of the shank portion 13 and the head portion 12 with less wear which are not subjected to earth and sand wear and the like are made of structural steel, for example, as compared with the case where the entire round pick body 11 is formed of tool steel. Since it is formed, it is economical and the concave curved surface portion 12B and the annular groove 13A can be formed relatively easily.

By the way, the front end of the round pick body 11 is made of a tool steel member and the rear end side is made of a structural steel member, and the two members are joined to form the round pick body 11. In the case of forming, for example, it is conceivable that the entire head portion 12 is formed of tool steel and the entire shank portion 13 is formed of structural steel. However, in such a configuration,
The head 12 having a small diameter where the joining surface of the two members having different materials is small
And the shank portion 13 is located at a connecting portion, which is not preferable because sufficient joining strength may not be obtained. Therefore, in the present embodiment, the head member 1 made of tool steel is partially extended to the middle of the cylindrical portion 12C at the tip of the head portion 12.
5 and the shank 13 on the rear end side
Up to the shank member 16, that is, both members 15, 1
The joint surface P of No. 6 is located on the cylindrical portion 12C of the head portion 12, so that the joint area (the area of the joint surface P) between the two members 15, 16 is secured, and sufficient joint strength is obtained.

In joining the head member 15 and the shank member 16 as described above, a method of joining the two by, for example, brazing is also conceivable, but such joining means is insufficient in strength. May be
Further, in this embodiment, since the brazing is also used when attaching the chip 14 to the tip of the head portion 12, both members 1
There is also a possibility that the joining accuracy of 5 and 16 may be adversely affected. On the other hand, in the present embodiment, when the head member 15 and the shank member 16 are joined, the members 15 and 16 are friction-welded to each other. It is possible to prevent a situation in which the joining accuracy is affected by brazing.

Further, in this embodiment, the tip side of the round pick body 11 is made of a tool steel head member 15 as described above.
The round pick body 1
(1) The hardness of the tip 14 around the tip 14 is set to _HRC 50 or more. If the hardness around the tip 14 is smaller than _HRC 50, the soil around the tip 14 may be worn when a large excavation load is applied. This is because there is a possibility that the above-mentioned conditions cannot be sufficiently suppressed. For this reason, as the tool steel forming the periphery of the tip 14 at the tip of the round pick main body 11, it is desirable to select a steel having a hardness of _HRC 50 or more as in the present embodiment, and specifically, _HRC 6
It is desirable to use a SKD11 material which is about 0.

[0015]

As described above, according to the present invention,
Although relatively inexpensive, it is possible to provide a round pick that can suppress sediment wear and the like on the head portion under conditions where a large excavation load acts, and can reliably hold chips for a long period of time to prevent the chips from falling off. , It is possible to extend its life.

[Brief description of the drawings]

FIG. 1 is a partially broken side view showing one embodiment of the present invention.

FIG. 2 is a partially cutaway side view showing a conventional round pick.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Round pick body 12 Head part 12C Column part of head part 13 Shank part 14 Tip 15 Head member 16 Shank member P Joining surface of head member 15 and shank member 16

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Takagi 1528 Nakashinda, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture Mitsubishi Materials Corporation Gifu Works (56) References JP-A-10-184259 (JP, A) JP-A-5-280273 (JP, A) JP-A-8-93377 (JP, A) JP-A-9-209678 (JP, A) JP-A-10-220154 (JP, A) −72992 (JP, U) Hira 3-46588 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) E21B 10/56

Claims (3)

(57) [Claims] 1. A together with the head portion which chip is protruded from the distal end of the round pick main body is provided, in round pick shank portion shaft-like is provided at the rear end of the round pick body, the head Is the part on the rear end side
Toward the tip end, a large-diameter disc and a concave
A column with a smaller diameter than the disk connected through the arc
The diameter gradually decreases from the tip of the cylindrical part toward the tip
If the truncated cone is coaxially integrated
In both cases, the round pick body is
The joint surface, which is a circular surface perpendicular to the center axis of the
It is composed of two members at the rear end side of the cylinder of the head.
Made are optionally round pick Among distal end side, characterized in that the rear end while being formed by tool steel is formed by structural steel. 2. The round pick body includes a tool steel head member forming a front end side of the head portion, and a structural steel shank member forming the rear end side of the head portion and the shank portion. The round pick according to claim 1, characterized in that the round picks are joined by friction welding. 3. The round pick according to claim 1, wherein the hardness of at least the periphery of the tip of the head portion of the round pick main body is _HRC 50 or more.