JP2003515021A - Threaded joint and male thread - Google Patents

Abstract

(57) [Summary] The present invention relates to a male screw member, a screw joint, and a male screw member for impact excavation. The threaded joint has at least one generally cylindrical outer thread (14) and one generally cylindrical inner thread (15). The outer thread (14) has a plug portion (12) that forms an integral part of the first drill string member (10A, 10B). Each of the screws has a screw end (21 to 24) connected to a screw portion of a perfect shape. Each screw (14, 15) has an end region with a minimum radius (R) in longitudinal section. The generally cylindrical outer thread (14) has a first axial length (L1), the generally cylindrical inner thread (15) has a second axial length (L2), By making the axial length (L1) shorter than the second axial length (L2), both end regions (23, 24) of the cylindrical inner peripheral screw (15) become cylindrical outer peripheral screws (14). ).

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a threaded joint for impact excavation and a male threaded member described in the preamble of each independent claim.

Conventional Technology Conventionally, for example, Swedish Patent Publication 469,602 and US Pat.
32 and 502, male and female screws are used for a screw type joint for fastening two members of a rock drill for impact excavation. To manufacture this male screw, a steel material is formed into a shape having a large diameter portion. Both ends of the large-diameter portion are connected to a small-diameter clearance surface or clearance groove into which at least a part of the thread cutting tool is inserted, and usually to a frustum-shaped free end. The large diameter portion is provided with screws in the usual way. Depending on the shape of the clearance groove and the free end surface, the screw inlet and outlet have sharp edges. Corresponding to this, a sharp edge is also formed on the threaded portion of the female screw. When using the joint, the sharp edges of the male and female threads will damage each other. The life of a joint is usually determined by a male screw.

OBJECTS OF THE INVENTION One of the objects of the present invention is to provide a long-lived screw joint of the type described above. Another object of the present invention is to provide a threaded joint of the above type which has a long life of the male screw.

The object of the invention is achieved by a threaded joint with the features defined in the claims. Embodiments of the present invention will be described below with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION The threaded joint 10 of the present invention desirably comprises two drill tubes or drill rods 10A, 10B, each drill rod 10A, 10B comprising:
A plug portion (spigot) protruding at one end, that is, a male screw portion 12, and a sleeve portion or a female screw portion 13 at the other end are provided. The plug part is a roughly cylindrical outer peripheral screw 1
4 and the sleeve is provided with a generally cylindrical inner peripheral thread 15. Screws 14, 15
Each preferably has a single inlet and a single outlet. In the state in which the screw type joint for impact excavation including the two drill rods 10A and 10B shown in FIG. It is included. In most cases, it is necessary to engage the screws by pressing the rods together while rotating them. Once the screws are engaged,
Further rotation of the rods abuts the free end surface 16 of the rod against the bottom 18 of the female threaded portion and / or the abutment surface 17 against the inner shoulder 19 surrounding the inner end of the plug portion 12. The screws 14 and 15 are designed so that the male screw and the female screw are abutted with each other only on a part of the side surface as in the conventional case. Do not make contact between curved parts or between the screw thread and the screw bottom. US Pat. No. 4,968,068
(Incorporated as part of this specification) shows a threaded joint in which the present invention can be utilized. The female threaded portion 13 forms part of the drill rod. Further, this drill rod has a through flow passage 2 through which a fluid, usually air or water, flows.
It has 0.

The external thread, that is, a substantially cylindrical outer peripheral thread 14, has at least one outer threaded end 21 and at least one inner threaded end 22 that are continuous from the thread of the complete shape. The female thread, or the generally cylindrical inner peripheral thread 15, has at least one outer threaded end 23 and at least one inner threaded end 24 that are continuous from the threaded portion of the complete shape. Each of the screw ends 21 to 24 has a sharp edge, because the clearances provided before the thread cutting, that is, the conical clearances 31 and 32 of the plug portion 12 and the cylindrical clearances 33 and 34 of the sleeve 13 are provided. Is. As shown in FIG. 3, this edge defines the minimum radius R of the screw in the longitudinal section.

The male screw 14 and the female screw 15 are related to each other in length and position so that both ends or both end regions 23, 24 of the female screw 15 do not come into contact with the male screw 14 when tightened. There is. Here, “does not contact” means that both ends 23, 23 are spaced from the male screw in a state where the joint is tightened. This state is secured as follows. The male screw 14 has a first axial length L1 between the screw ends 21 and 23, and the female screw 15 has a second axial length L2 between the screw ends 23 and 24.
Is. The length L1 is shorter than the length L2. In other words, the frustum-shaped clearance 31
, 32 is shorter than the distance between the cylindrical clearances 33, 34. With the joint tightened, the distance L3 between the free end surface 16 of the plug portion 12 and the inner thread end or end region 24 of the female screw 15 is It is shorter than the distance L4 from the partial region 21. The same is true for the outer ends of the joints. That is, with the joint tightened, the distance L5 between the shoulder portion 19 of the plug portion 12 and the outer thread end portion or the end region 23 of the female screw 15 is set.
Is the distance L between the shoulder portion 19 of the plug portion and the inner screw end or end region 22 of the male screw.
Shorter than 6.

There are frustum-shaped guide surfaces 25, 26 at the outer and inner ends of the plug portion 12, which are axially co-operating with the respective frustum-shaped guide surfaces 27, 28 on each side of the female thread 15. Works. The virtual frustum apex of the frustum-shaped guide surface faces the direction F of impact. The length L1 of the male screw 14 is 50 to 80% of the length L of the ship member. The screw end regions 21 and 22 on both sides of the male screw 14 are respectively distances L4 and L from both ends 16 and 19 of the plug portion.
It is provided in 6.

Although a frustum-shaped screw is shown in the above embodiments, the present invention can be applied to all impact rock drill screws, for example, rope screws. The female thread portion or the male thread portion may be provided on the rock drill bit instead of being provided on the drill rod or the drill tube. FIG. 4 shows an example in which the screw joint of the present invention is applied to a rock drilling bit 10C for impact rock drilling equipped with a hard metal button. In the figure, the same reference numerals as above are used.

The principles of the present invention can be applied to a threaded joint that fastens a plug adapter and a drill rod, or to a threaded joint that fastens between two drill rods with a loose extension sleeve. You can also From another point of view, the present invention can be freely modified within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a threaded joint according to the present invention fastening two drill members of the same shape.

[Fig. 2]   FIG. 2 is a perspective view of the male screw member of the present invention.

[Figure 3]   FIG. 3 is a sectional perspective view of the female screw member of the present invention.

FIG. 4 is a cross-sectional view of a threaded joint of the present invention fastening a rock drill bit and a drill.

Claims (6)

[Claims] 1. A threaded joint for impact drilling, comprising at least one generally cylindrical outer peripheral screw (14) and one generally cylindrical inner peripheral screw (15),
The outer peripheral screw (14) is located on the plug portion (12) and is located on the first drill string member (
10A, 10B, 10C) and each of the screws has a threaded end (21-24) that is continuous with the threaded portion of the complete shape.
, 15) has an end region having a minimum radius (R) in a longitudinal cross section, wherein in the screw joint, the substantially cylindrical outer peripheral screw (14) has a first axial length (L1). However, the substantially cylindrical inner peripheral screw (15) has a second axial length (L2), and the first axial length (L1) is the second axial length (L2). ), Both end regions (23, 24) of the inner peripheral screw (15) are made smaller than the outer peripheral screw (14).
A screw type joint characterized by not contacting with. 2. A shoulder (19) at the inner end of the plug portion (12) has an abutment surface facing the free end of the plug portion (12) and the inner peripheral screw (15). A threaded joint according to claim 1, wherein a sleeve formed with a second drill string member is continuous with the second drill string member, the sleeve having an inner abutment surface (18). 3. The free end surface (16) of the plug portion (12) and the inner peripheral screw (1).
The distance (L3) from the inner end region (24) of 5) is the distance (L4) between the free end face (16) of the plug portion (12) and the outer end region (21) of the outer peripheral screw (14). The distance (L5) between the inner end (19) of the plug portion (12) and the outer end region (23) of the inner peripheral thread is shorter than the inner end of the plug portion and the outer peripheral thread. Threaded joint according to claim 1, which is shorter than the distance (L6) from the inner end region (22). 4. The outer and inner ends of the plug portion (12) operate in cooperation with the frustum-shaped guide surfaces (27, 28) at both axial ends of the inner peripheral screw (15). Threaded joint according to claim 4, characterized in that there is a frustum-shaped guide surface (25, 26). 5. A male screw member constituting a part of a screw joint for impact excavation, comprising at least one substantially cylindrical outer peripheral screw (14), said outer peripheral screw (14) being a plug portion ( 12) the first drill string member (10A, 1
0B) which is an integral part of the screw (14), the screw (14) has a threaded end (21, 22) which is continuous with the thread of the complete shape, and the screw (14) has a minimum radius in the longitudinal section. There is an end region of (R) and the plug portion (12) has a length (L),
In the male screw member, the length (L1) of the generally cylindrical outer peripheral screw (14) is the length (L) of the plug portion.
50% to 80% of the inside of the plug portion (12), the end regions (21, 22) of the outer peripheral screw (14) being spaced from the end portions (16, 19) of the plug portion. Male screw member, characterized in that the shoulder (19) at the end has an abutment surface facing towards the free end of the plug portion (12). 6. The male screw member according to claim 5, wherein the outer and inner ends of the plug portion (12) have frustum-shaped guide surfaces (25, 26).