JPH0751938A - Thread cutting device for steel pipe - Google Patents

Abstract

PURPOSE:To provide a thread cutting device, by which the efficiency above that of a tool rotating type can be obtained without damaging the characteristics of a pipe rotating type to make the thread cutting efficiency for a seamless steel pipe equal to that of API screw by small modification of an existing thread cutting machine. CONSTITUTION:In a pipe rotation type thread cutting machine, a fixed circular block 1 is arranged on the outer periphery of a pipe, and plural slide bases 2, and tool rests 3,4 are installed on the circumference to enable simultaneous cutting with plural cutters and obtain high efficiency. Further, the quality can be ensured and the capacity (equal to that of the existing API) above that of the pipe rotating type can be obtained without any increase in the number of machines to be installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting device for steel pipes, for example, for thread cutting for connecting oil country tubular goods, particularly for manufacturing special joints having complicated shapes.

[0002]

2. Description of the Related Art Two types of screw cutting machines, a pipe rotating type and a blade rotating type, are mainly used for mass production. In the pipe rotation type, a tool post or turret is usually arranged at the rear and front, and a plurality of tools are attached to this, and numerical control is performed, so that a plurality of delicate movements are possible. Therefore, it is suitable for manufacturing a special joint having a metal-to-metal seal portion.

However, this type has a drawback that productivity is inferior due to a structure requiring extra time for transporting the pipe and a limit on the number of cutting tools that can be used at the same time.

Particularly in the cutting of thin-walled pipes, in order to improve efficiency, if the cutting amount per blade is large,
Due to the deformation of the pipe to be cut, an accurate finished shape cannot be obtained. For this reason, a turret or turret having several knives is used, and by switching these turrets, the cutting amount per blade is reduced. That is, the machining time becomes long because a large number of cutting tools cannot be used at the same time, and when a turret is used, an operation time for selecting a target cutting tool is required.

On the other hand, the rotary knife type compensates for the above-mentioned drawbacks due to its structure, that is, the pipe conveying time is short, and several cutting tools can be installed in the rotating holder, and simultaneous cutting can be performed, so that the pipe rotating Higher productivity can be obtained compared to the mold.

However, since it is necessary to store the blade driving device in a limited space, its operating range and type are naturally limited, and in order to finish a special joint having a complicated shape, another function is shared. It is common for equipment to be used in combination.

[0007]

The problem to be solved by the present invention is to take advantage of the characteristics of the pipe rotating type in the production of screws for connecting oil well pipes, especially special joints having complicated shapes. The invention provides a threading device for a steel pipe, which allows a cutting tool to perform complicated and delicate movements and can achieve high productivity.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to a pipe rotary type threading machine, in which a fixed annular slide block is arranged on the outer circumference of a pipe, and slide bases are arranged at two or more locations on the inner circumference of the block. , A special tool rest is installed on this slide base.

The ring-shaped slide block has a circular or polygonal shape and is used by being fixed, but it may be a movable type for special purposes. The dedicated tool rest on the slide base can feed independently in the direction toward the center of the pipe and the direction of the pipe axis, in the forward and reverse directions.

In FIG. 1, an annular slide block 1
Via the rear chuck R, the drive unit M, the front chuck F, and the centering device C, which have the same structure as the conventional pipe rotation type thread cutting machine, are located at the place where the tool rest was installed. In FIG. 2, the slide base 2 is provided at two or more locations (8 locations in this figure) on the circumference of the annular slide block 1.
Is arranged. Each of the slide bases 2 is installed toward the center of rotation of the pipe. The slide base is provided with a Z-axis tool rest 3 and an X-axis tool rest 4, and a necessary cutting tool is attached to the tool holder 5.

These are driven by servomotors 6 and 7. The servomotor is controlled by a copying device, a numerical control device, or the like. Each stroke is
Z axis 5 when processing pipe sizes 4 1/2 "to 16"
00 mm and X-axis 300 mm are all that is required. Of course, it is necessary to select an appropriate value depending on the type and size of the joint.

[0012]

[Embodiment] Each of eight tool holders shown in FIG. 2 includes a square tool for screw-down machining, a checker for rough screw finishing, a checker for screw finishing, a diamond tool for rough machining of seal parts, and a diamond tool for finishing seal parts. When equipped with a sticker cutting tool, chamfering round piece tool, and inner diameter finishing round piece tool, and controlled by the numerical control device, the cutting time is about half that of the conventional method, and the overall machining efficiency is improved. It is possible to increase by about 1.8 times.

[0013]

By employing the device of the present invention, the following can be realized. Since the blades of the same purpose can be placed on the same circumference, the cutting load per blade can be reduced to less than 1/2, and moreover, it is possible to perform cutting at almost the same time, and to select the target cutting tool. Since the dynamic operation time is unnecessary, the cutting time can be shortened to 1/2 or less of the case of one blade. In the rotary knife type, it is usually necessary to share the processing of the seal portion, which requires precision finishing, with another facility. Therefore, misalignment caused by re-chucking the pipe is 0.15
mm to 0.20 mm or less. According to the present invention, since it can be completed in its own facility without sharing it with another facility,
There is no problem of misalignment and the sealing accuracy of the joint is not impaired. In addition, since it is not necessary to increase the number of facilities, the equipment installation area can be minimized and the number of operators can be prevented from increasing. As described above, it is possible to provide a large productivity with a minimum area and a minimum number of units while ensuring accuracy.

[Brief description of drawings]

FIG. 1 is an overall view of a rotary pipe threading machine of the present invention.

FIG. 2 is an annular slide block and a slide base,
It is a detailed layout drawing of a tool post.

[Explanation of symbols]

 1 Annular slide block 2 Slide base 3,4 Turret 5 Tool holder 6,7 Servo motor

Claims (1)

[Claims] 1. A fixed annular slide block is arranged on the outer circumference of the pipe, slide bases are arranged at two or more locations on the inner circumference of the block, and a dedicated tool rest is installed on the slide base. Pipe rotating type thread cutting device.