JPS58151915A - Production of pipe having both upset ends - Google Patents

Abstract

PURPOSE:To produce a pipe having both upset ends of a large diameter and a large thickness easily, by using a punching device for producing pipes and by changing some members of the material and a working method. CONSTITUTION:A bottomed blank pipe is put on a mandrel 3 of which the preceding end has a small diameter and the body has a large diameter, and while the blank pipe is passed through a die, the same is rolled until the outside diameter of the blank pipe P1 is reduced to the desired outside diameter UD in the upset part. Further, the blank pipe is passed through a die 4 of small diameter and is worked until the body of the pipe attains the required thickness t1. The reducing operation is stopped in this stage to form the upset part U1 of the outside diameter UD of a prescribed length in the succeeding end part of the pipe. The mandrel 3 is retreated together with the material and a backing plate 5 having a reducing hole 5 of a slightly larger diameter through which the large diameter part of the mandrel 3 passes in place of the die 4 is installed in front of the die. The top end P1 of the blank pipe P2 is brought into contact with the plate 5 and the mandrel 3 is advanced to punch through the bottom of the top end of the pipe; at the same time, the thick walled part M1 of the pipe P2 is pushed outward by the tapered part 3c and large diameter part 3a of the mandrel 3, whereby an upset part U2 is formed on the outside circumference of the top end part P1 of the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a double-end upset tube, and more particularly, to a method for manufacturing a double-end upset tube by a punching method, the so-called Erhard-Butschbench tube manufacturing method.

In general, connections between pipes are often made by welding, but special connection methods are required, such as in the case of oil country tubular goods.
In such cases, a coupler connection is used. In this case, in order to compensate for the decrease in strength of the threaded portion, the pipe end portion, which is the threaded portion, is usually made into an upset shape in advance. In the case of small-diameter or medium-diameter thin-walled pipes such as oil country tubular goods (outer diameter: maximum 400111111 wall thickness: maximum 3 oIl), upset processing is relatively easy, and efficient abscenters have been put into practical use. However, on the other hand, large-diameter thick-walled pipes (outer diameter: 25o~
80 mm, wall thickness = 15 to 150 iua), there are few uses that require screw connections up to A, and it is rare to perform upset processing on such large-diameter, thick-walled pipes. In order to obtain an upset tube, instead of hot upsetting forging as in the case of small diameter tubes, the outer surface of the central portion, leaving both ends of the tube, was machine cut, which took a considerable amount of time. As exploration for manganese nodules in the deep seabed progresses and methods for collecting slurry are studied, large-diameter, thick-walled pipes with screw connections similar to oil country tubular goods are needed. In this case, conventionally known upsetters cannot be used, and mechanical cutting is not efficient, so a new manufacturing method is strongly desired.
was.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for economically and efficiently manufacturing a large-diameter, thick-walled double-ended upset tube. In the punching process of the so-called Erno-Luto-Butschbench pipe manufacturing method, a specially shaped mandrel with a small diameter tip is used, and the punching of the outer diameter of the raw pipe with an eave is stopped midway to attach the eave. A first outer upset part is formed at the front and rear ends of the opening of the raw pipe, and then the bottom part of the raw pipe with eave is pierced by punching out the mandrel using a contact plate instead of a die, and at the same time, a first outer upset part is formed on the bottom side. Next, the present invention will be explained in detail with reference to the drawings. In general, the punching pipe manufacturing method, the so-called Erno route
In the Pushi-Yubenchi pipe manufacturing method, as shown in Fig. 1, first, a steel ingot M is heated (a) and then charged into an inverted cone-shaped pot 1, and a mandrel 2 is pressed from above to form a vertical press perforation (so-called Erhardt drilling) to obtain a press-shaped eave-equipped raw pipe P+ (b) o Next, the raw pipe P+ is pressed against a horizontal pressing mandrel 3.
The 0 punching method, in which the material is charged into the tube and passed through a tandem die 4' and rolled to a predetermined outer diameter and wall thickness, is the tandem die method, in which multiple dies are set at regular intervals and punched out with one push. However, the single-die method, in which one die is punched in one punch and multiple dice are punched in multiple punches, is also possible.In this punching process, the outer diameter OD determined by the final passing die and the outer diameter of the mandrel 3 are determined. A finished pipe P2 with a garden having an inner diameter ID determined by the above and a length determined by the weight of the steel ingot used is obtained (d). After this, the finished pipe P
Cut both ends of 2, and after heat treatment, remove the inner and outer surfaces! .

The product is processed by grinding or turning.

The present invention forms upset-shaped parts at both ends of the tube by partially modifying the tool and processing method in the punching process using the Erno Tsuta Pussy Pliers tube manufacturing method. To explain, the mandrel 3 used in the punching process according to the method of the present invention is as follows:
As shown in FIG. 2, the outer diameter od of the large diameter portion 3a has a large diameter portion 3a of the main body, a small diameter portion 3b at the tip, and a tapered portion 3C connecting the large diameter portion 3a and the small diameter portion 3b! Since this substantially determines the inner diameter ID of the finished pipe P2, it can be selected as appropriate depending on the desired outer diameter OD and wall thickness of the finished pipe P2.
The outer diameter o of the small diameter portion 3b formed at the tip of the O mandrel 3
The shapes of dz and the tapered portion 3C are selected so that a second outer upset portion having a desired shape can be formed at the distal end portion Pf of the tube, as described later.

The shape of the tapered portion 3c is designed to facilitate the middle expansion process described later and to obtain a desired upset shape. As shown in FIG. 3(a), as shown in FIG.
After that, the raw pipe P1 is rolled until the outer diameter of the raw pipe P1 becomes approximately the desired outer diameter UD of the upset part.The raw pipe P1 is then further passed through a die 4 having a smaller diameter, as shown in FIG. 3(b). , the tube body is processed until the desired wall thickness t1 is obtained. At this time, the stroke of the punching operation is the second raw pipe P
2 so as to leave a predetermined length of the punched-out portion at the rear end Pr of 2. In other words, if you stop the punching operation midway,
A first outer upset portion U having an outer diameter UD at a predetermined length at the front and rear ends.
1 (intermediate step 2).

After forming the first outer upset portion Ul at the front and rear ends Pr,
Once the mandrel 3 is moved back together with the material, the die 4
Instead, a touch plate 5 is installed in front. This plate 5 has a punched hole 5a having a diameter slightly larger than the diameter t through which the large diameter portion 3a of the mandrel 3 can pass. The mandrel can also be provided with suitable guide means for positioning the outer surface of the blank tube P2 so that the mandrel 3, and therefore the blank tube P2, abuts against the contact plate 5 in a centered state.

Thus, by bringing the tip Pf of the raw pipe P2 into contact with the contact plate 5 and moving the mandrel 3 forward, the bottom of the pipe tip is strongly pierced, and the raw pipe Pf is pushed through the tapered portion 3C and large diameter portion 3a of the mandrel 3. The thick part M1 of P2 is pushed out to the outside in an expanded state, and a second outer upset part U is formed on the outer periphery of the pipe tip part Pf.
Form into z'. In this case, it is important to design the shape of the mandrel 3 in advance so that the outer diameter of the upset part U2 is the same as the outer diameter of the first outer upset part. The finished pipe P3 having an upset part is subjected to heat treatment, etc., as well as ordinary pipes manufactured by the Erhardt pipe manufacturing method, and then internally and externally milled to finally adjust dimensions and remove surface defects. Receive input. Thereafter, threading is applied to the upset part.As mentioned above, in the present invention, in the punching process, some punching is omitted to ensure the outer diameter of the upset part. The forging ratio of the material will be different in the direction.

However, this variation in forging ratio is removed in the heat treatment process described above, so there is no problem. Further, it is more preferable that the forging ratio of the above-mentioned part where the punching is omitted is at least the necessary minimum forging cost.

In the above example, all the pressing plate processes were performed using the same mandrel, but the shape of the mandrel was
Other conventional mandrels can also be used in the preceding processing steps, as they are only required for the processing of the outer upset portion and the steps immediately preceding it. However, there is a disadvantage that the mandrel must be changed.

As is clear from the above, according to the present invention,
In practice, existing equipment can be used as is, with only some parts and processing methods changed. A thick-walled double-ended upset tube can be easily manufactured. Therefore, the present invention can economically and efficiently produce a large-diameter, thick-walled double-end upset tube.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the general process of the punching pipe manufacturing method, Figure 2
The figure is a front view showing the mandrel used in the present invention, and FIG. 3 is an explanatory diagram showing the manufacturing process of the double-end upset tube according to the present invention.

Claims (1)

[Claims] (1) A die with a diameter smaller than the outer diameter of the core pipe is placed over a mandrel whose tip part has a small diameter and a main body has a large diameter. The inside of the die having holes is punched out halfway to form a thick-walled first outer upset part at the open diameter end of the gardened raw pipe, and then the gardened tip of the gardened raw pipe is inserted into the mandrel body part. With the mandrel in contact with a backing plate that has a punched hole with a diameter slightly larger than the diameter of the mandrel, move the mandrel forward until the large diameter part passes through the punched hole in the backing plate to break through the bottom of the base pipe. Method 0 for manufacturing a double-end upset tube characterized by forming a thick second outer upset portion at the tip of the tube by