JPS59201720A - Working for tapered screw - Google Patents

Abstract

PURPOSE:To carry-out thread cut perfectly to an Lc point from a pipe body even if a pipe edge is curved or centering error exists by carrying-out centering for an article to be worked at the Lc point. CONSTITUTION:Centering is performed by a fixed chuck not shown in the figure and a positioning chuck 3. Though positioning of the positioning chuck 3 is carried-out by a cylinder 4 and a motor 5, the position in the axial direction of the positioning chuck 3 is accorded with the Lc point of a steel pipe 1. Thus, centering of the Lc point is carried-out, and then a floating chuck 2 is fixed, and the positioning chuck 3 is released, and the thread cutting work is carried-out.

Description

[Detailed description of the invention] The present invention relates to a method for processing a tapered thread.

Generally, long lengths such as oil country tubular goods are connected by coupling with a taper channel cut at the end of the pipe, but the screws □ are required to be airtight, so high dimensional accuracy is also required.

By the way, as shown in Fig. 1, a tapered thread is divided into a completely threaded part Lct without a black skin and an incomplete thread part Lut with a black skin remaining, and the pipe end is cut at the upper p end Lu of the thread.
The length T and cl of the complete thread portion relative to the length at i (Lct+Lut) are determined for each thread size. The position corresponding to the boundary between the fully threaded portion and the incompletely threaded portion according to this standard is called the Lc point. Therefore, in actual thread cutting, L is determined for each thread dimension.
No black skin is allowed to remain at the c point, and a complete thread must be formed.

Conventionally, in this type of thread cutting, although the Lc point varies depending on the thread size, the variation is not large, so processing is performed by centering at a fixed position that corresponds to the average value. was.

However, there was a bend at the end of the tube, and due to poor centering at 75, a black crust remained on the Lc point, making it impossible to form a complete thread.

The present invention was invented in view of this situation, and even if the tube end has a bend or centering failure,
The present invention provides a method for processing a tapered thread in which the length from the tube end to the Lc point is completely threaded.

The tapered thread processing method according to the present invention is characterized in that thread processing is performed by centering the workpiece using an Lc bond.

Next, embodiments of the present invention will be described based on the drawings. Second
The figure is an explanatory view of a rotary tool type thread cutting device that implements a method according to an embodiment of the present invention.

In Figure 2, (1) is a steel pipe, (2) is a floating chuck, (3) is a positioning chuck,
It is configured to be movable in the axial direction. (4) is a cylinder that moves the positioning chuck (3) up and down; (5)
is a motor that moves the positioning chuck in the tube axis direction.

Centering is performed using a fixed chuck and a positioning chuck (3) (not shown). At this time, the positioning chuck (3) is positioned by the cylinder (4) and the motor (5), and the position of the positioning chuck (3) in the tube axis direction is made to coincide with the Lc point of the steel tube (1). In this way, center alignment is performed at the Lc point, and then the floating chuck (2)
, release the positioning chuck (3), and begin thread cutting.

The results of thread cutting after centering the steel pipe () at the Lc point in this manner are shown in FIG. 3 together with the results of the conventional method. In this figure, the vertical axis shows the outer diameter, 0% shows the reference nominal outer diameter, the horizontal axis shows the pipe end, and the human area is centered using the conventional method. The region B shows the region where the test was passed when processing was performed using the above-mentioned method. As is clear from this figure, the method according to the above-mentioned embodiment has a wider acceptance range, and therefore allows highly accurate machining even if there are tube end cracks and centering defects.

In addition, although the above-mentioned embodiment showed an example of a tool rotation type device, it goes without saying that the present invention is similarly applied to a tube rotation type device.

As is clear from the above explanation, the method according to the present invention
The positioning chuck is configured to be movable independently in the axial direction, and the chuck performs centering at the Le point of the workpiece. Within a certain range, sufficient machining accuracy can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional diagram of a tapered thread, FIG. 2 is an explanatory diagram of a thread cutting device to which a method according to an embodiment of the present invention is applied,
FIG. 6 is a characteristic diagram of the results of the above example. (1)...Steel pipe, (2)...Floating chuck, (3)...Positioning chuck, (4)...
・Cylinder, (5)...Motor. Agent Patent Attorney Sanro Kimura Figure 1 Figure 2 Figure 14 1972-201720 (3) Figure 3 % τ Nakitotsu

Claims (1)

[Claims] The positioning chuck is configured to be movable independently in the axial direction of the workpiece, and the positioning chuck is configured to be movable independently in the axial direction of the workpiece.
A method of processing a tapered screw, which is characterized by centering at a point and then cutting the thread.