JP2020199516A - Method for manufacturing pipe member with closed end - Google Patents

Abstract

To manufacture a pipe member of which closed part is reliably sealed, of which closed part is sufficiently thickened and of which end is closed, in short time.SOLUTION: A method for manufacturing a pipe member with a closed end manufactures a pipe member with a closed end by using a molding device with a heating device, a die and a punch for a metal pipe to be a raw material in a longitudinal direction, and includes the steps of: heating an end of the metal pipe using the heating device; drawing and molding an open end in a heated region of the metal pipe using the die; pressing the metal pipe using the punch; and sealing the open end of the metal pipe.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing a pipe member having a closed end.

For example, hollow pipe members have been conventionally used for automobile parts such as piston rods and stabilizers. These tube members are usually manufactured by closing the ends of metal tubes.

Patent Document 1 includes a cylinder and a molding spatula in contact with the cylinder, and by rotating the cylinder or the molding spatula, the end of the cylinder is closed outward while the squeezed portion is exposed, and then the squeezing is performed. A method of closing the end of a cylindrical body that melts the portion is disclosed.

Patent Document 2 describes a die having a linearly extended pipe fitting hole and a large-diameter hole having a diameter larger than that of the pipe fitting hole formed near one end of the pipe fitting hole, and a die that can be fitted into the large-diameter hole. This is a processing method that uses a large-diameter cylindrical punch and a small-diameter cylindrical punch that can slide inside the large-diameter punch and fit into the pipe fitting hole. One end of the pipe is specified in the large-diameter hole. Insert it into the pipe fitting hole so that it protrudes by the length, integrate the large diameter punch with the small diameter punch, fit it into the large diameter hole, crush the upper end of the pipe protruding into the large diameter hole, and then crush only the small diameter punch. A processing method of moving the pipe to fit it into the pipe fitting hole and closing one end of the pipe is disclosed.

In Non-Patent Document 1, the raw pipe is processed by a swaging processing device, the processed portion is heated by a heating device, and the pipe is compressed in the axial direction after heating by using a hydraulic press or a crank press. A processing method for closing the end portion is disclosed.

Japanese Unexamined Patent Publication No. 61-119334 Japanese Unexamined Patent Publication No. 61-189838

Masanobu Nakamura "Pipe Processing Method" Nikkan Kogyo Shimbun, 1982

An important point in the method for manufacturing a pipe member having a closed end is that the closed portion is surely sealed and that the closed portion is sufficiently thickened. When applied to the manufacture of automobile parts and the like, it is important from the viewpoint of cost that the pipe member can be manufactured in a short time.

The present inventors have earnestly studied a method for manufacturing a pipe member having a closed end to solve the above-mentioned problems, and have made the present invention. The summary is as follows.

(1) A method for manufacturing a pipe member in which at least one end is closed, using a molding device provided with a heating device, a die, and a punch in the longitudinal direction of a metal pipe as a material. A step of heating the end portion of the metal tube, forming the heated region of the metal tube by mouth drawing with the die, pushing the metal tube with the punch, and sealing the end portion of the metal tube is provided. A method for manufacturing a pipe member whose end is closed.

(2) The above-mentioned (1), wherein the heated metal tube is moved in the longitudinal direction relative to the heating device after the completion of the heating and before the mouth drawing molding. A method for manufacturing a pipe member whose end is closed.

(3) A method for manufacturing a pipe member in which the end of (1) or (2) is closed, wherein the metal pipe is a steel pipe.

(4) The method for manufacturing a pipe member in which the end of any one of (1) to (3) is closed, wherein the molding apparatus further includes a mold for holding the metal pipe.

(5) The method for manufacturing a tube member in which the end of any one of (1) to (4) is closed, wherein the heating means is high-frequency induction heating, energization heating, or gas burner heating. ..

(6) The end of any one of (1) to (5) is characterized in that the surface of the punch in contact with the metal tube has a concave shape in which the central portion is recessed on the opposite side to the metal tube. A method for manufacturing a closed pipe member.

(7) The end portion according to any one of (1) to (6) above, which satisfies the condition that the time from the end of the heating to the start of the mouth drawing molding is 0.1 s or more and 32 s or less. A method for manufacturing a pipe member in which is closed.

を満たすことを特徴とする前記（１）〜（７）のいずれかの端部が閉塞された管部材の製造方法。 (8) The thickness of the metal tube is t ₀ (mm), the outer diameter is d ₀ (mm), the outer diameter after sealing is d ₂ (mm), and the length of the planned thickening portion is L ₂ (mm). When, the heating range L ₀ (mm) is

A method for manufacturing a pipe member in which the end of any one of (1) to (7) is closed.

を満たすことを特徴とする前記（１）〜（８）のいずれかの端部が閉塞された管部材の製造方法。 (9) The plate thickness of the metal pipe is t ₀ (mm), the outer diameter is d ₀ (mm), the length of the region where the metal pipe is heated in the longitudinal direction is L ₀ (mm), and the pipe after sealing. When the outer diameter of the closed end of the member is d ₂ (mm) and the length of the planned thickening part is L ₂ (mm)
The pushing amount _St (mm) of the punch is

A method for manufacturing a pipe member in which the end of any one of (1) to (8) is closed.

(10) The end according to any one of (1) to (9) above, characterized in that the time from the start of the mouth drawing molding to the completion of detachment of the manufactured pipe member from the die is 10 s or less. A method for manufacturing a pipe member whose portion is closed.

According to the present invention, it is possible to manufacture a pipe member having a closed end portion in which the closed portion is surely sealed and the closed portion is sufficiently thickened in a short time.

It is a figure explaining the outline of the end part of the pipe member whose end part was closed. It is a figure which shows the outline of the molding apparatus used in the manufacturing method of this invention. It is a figure explaining the preferable heating range in the manufacturing method of this invention.

Hereinafter, an example of an embodiment of a method for manufacturing a pipe member having a closed end portion of the present invention will be described.

The method for manufacturing a pipe member of the present invention is to manufacture a pipe member by closing at least one end of a metal pipe as a material. At the end, as shown in FIG. 1, the hollow portion 12 of the metal tube 11 is sealed, and the thickened portion 13 is formed by increasing the thickness of the tube from the portion where the diameter of the hollow portion becomes smaller to the tip portion. The metal pipe as a material is not particularly limited, but the present invention is suitable for manufacturing a pipe member using a steel pipe.

In the manufacturing method of the present invention, as outlined in FIG. 2, a molding device in which a heating device 21, a die 22, and a punch 23 are coaxially provided in the longitudinal direction of the metal tube 11 as a material is used. As a result, it is possible to manufacture a tube member having a closed end as a series of steps without moving the metal tube after heating or drawing the mouth. Further, a mold 24 for holding the metal tube 11 may be provided to fix the metal tube 11.

The manufacturing process will be described.

First, the end of the metal tube is heated with a heating device. As the heating device, for example, an IH coil can be used for high frequency induction heating. In addition, energization heating, gas burner heating, and the like can be used. This heating is for facilitating the mouth drawing in the next step, and the conditions are not particularly limited, but it is a guideline to heat up to the austenite region where the deformation resistance is lowered.

If the length of the heated region at the end of the metal pipe in the longitudinal direction (hereinafter referred to as the "heating range") is too small, only the vicinity of the tip of the metal pipe will be thickened, and the entire planned thickening portion (see FIG. 1). Does not increase the wall thickness, and the processing power increases. If the heating range is too large, the thick range will be thickened, and as a result, the thickening and sealing will not be sufficient.

As a result of various experiments conducted by the present inventors, the thickness of the metal tube before molding is increased by t ₀ (mm), the outer diameter is increased by d ₀ (mm), and the outer diameter after sealing is increased by d ₂ (mm). When the length of the planned meat portion is L ₂ (mm), the heating range L ₀ (mm) is preferably set to the following range (FIG. 3). The seal will be described later.

After heating, the IH coil is removed from the vicinity of the heating part. For example, if an IH coil in which half of the coils are connected by a copper wire is used, the IH coil can be released in the plane direction perpendicular to the longitudinal direction of the metal tube, and the heated region can be formed by the die 22.

Alternatively, the metal tube may be moved in the longitudinal direction relative to the IH coil. For example, in FIG. 2, the IH coil (heating device 21) may be moved downward, or the metal tube 11 may be moved upward. If the energization of the IH coil is stopped before the movement, the metal tube will not be heated after the movement.

Next, the heated region of the metal tube is drawn by mouth with a die 22. The metal tube and the die 22 are relatively moved so that the heating region of the metal tube enters the inside of the die 22. As a result, the metal tube is drawn by mouth along the internal shape of the die 22. In the method for manufacturing a tube member of the present invention, since the metal tube is heated and then molded immediately, the metal tube is molded in a state where the deformation resistance of the metal tube is sufficiently low.

When the metal tube is heated, the heat generated near the outer surface becomes the largest, and a certain amount of time is required to conduct the heat in the plate thickness direction. Therefore, it is preferable to start the processing 0.1 s or more after the end of heating. Further, if the metal pipe is cooled by air cooling (cooling) until the start of processing, the deformation resistance of the metal pipe increases, which makes processing difficult. Therefore, the time until the start of processing is preferably 32 s or less.

Since the temperature of the unheated region of the metal tube is low, that is, it is hard, even if the die is simply pushed into the metal tube, it does not buckle.

The die 22 may be heated to cool the mold 24. Further, the shape of the inside of the die may be a one-step taper shape as shown in FIG. 1 or a shape having a multi-step taper.

Next, the metal tube formed by mouth drawing is pushed in with a punch to seal the end portion of the metal tube, and the tube member is completed.

If the punch pushing amount is too small, sufficient wall thickness cannot be obtained. Further, if the pushing amount is too large, the processing force becomes too large. Therefore, it is preferable to set the pushing amount within an appropriate range.

As a result of various experiments conducted by the present inventors, the plate thickness of the metal tube is t ₀ (mm), the outer diameter is d ₀ (mm), the heating range is L ₀ (mm), and the outer diameter after sealing is d. _{When 2} (mm) and the length of the planned thickening portion are L ₂ (mm), it is preferable that the pushing amount _St (mm) is in the following range.

The surface of the punch may have a flat shape or a concave shape that is recessed on the opposite side of the metal tube into which the central portion of the punch is pushed.

The pipe member whose punch has been pushed in is separated from the die. At that time, if the contact time between the pipe being processed and the die is long after the start of processing, the temperature of the die rises, and wear and damage are likely to occur, which is not preferable. Therefore, it is preferable that the time from the start of processing to the completion of processing and the completion of detachment of the manufactured pipe member from the die is 10 s or less.

Through the above series of steps, it is possible to manufacture a pipe member whose end is closed in about a few seconds.

For convenience, the description has been made using a configuration in which the metal pipes are arranged so that the vertical direction is the longitudinal direction, the heating device is arranged below, and the dice and punch are arranged above, but the orientation of the arrangement is limited to this. Needless to say, it is not. For example, it is clear that the same effect can be obtained by turning it upside down or turning it sideways.

Further, the method for manufacturing a pipe member having a closed end portion of the present invention is not limited to the method of closing one end, but a method for manufacturing a hollow member having both ends closed by the same method. Needless to say, it can also be applied to.

11 Metal tube 12 Hollow part 13 Thickening part 21 Heating device 22 Die 23 Punch 24 Mold

Claims (10)

A method for manufacturing a pipe member in which at least one end is closed.
Using a molding device equipped with a heating device, a die, and a punch in the longitudinal direction of the metal tube used as the material.
The end of the metal tube is heated by the heating device,
The heated region of the metal tube is mouth-drawn with the die and molded.
A method for manufacturing a pipe member having a closed end, comprising a step of pushing the metal pipe with the punch and sealing the end of the metal pipe. The end according to claim 1, wherein the heated metal tube is moved in the longitudinal direction relative to the heating device after the completion of the heating and before the mouth drawing molding. A method for manufacturing a pipe member in which is closed. The method for manufacturing a pipe member whose end is closed according to claim 1 or 2, wherein the metal pipe is a steel pipe. The method for manufacturing a tube member whose end is closed according to any one of claims 1 to 3, wherein the molding apparatus further includes a mold for holding the metal tube. The method for manufacturing a tube member whose end is closed according to any one of claims 1 to 4, wherein the heating means is high-frequency induction heating, energization heating, or gas burner heating. The end portion according to any one of claims 1 to 5, wherein the surface of the punch in contact with the metal tube has a concave shape in which the central portion is recessed on the opposite side to the metal tube. A method for manufacturing a pipe member. The end according to any one of claims 1 to 6, wherein the time from the end of the heating to the start of the mouth drawing molding is 0.1 s or more and 32 s or less is satisfied. A method for manufacturing a pipe member. When the plate thickness of the metal tube is t ₀ (mm), the outer diameter is d ₀ (mm), the outer diameter after sealing is d ₂ (mm), and the length of the planned thickening portion is L ₂ (mm). , Heating range L ₀ (mm),

The method for manufacturing a pipe member having a closed end according to any one of claims 1 to 7, wherein the method is satisfied. The plate thickness of the metal pipe is t ₀ (mm), the outer diameter is d ₀ (mm), the length of the region where the metal pipe is heated in the longitudinal direction is L ₀ (mm), and the pipe member is closed after sealing. When the outer diameter of the edge is d ₂ (mm) and the length of the planned thickening part is L ₂ (mm)
The pushing amount _St (mm) of the punch is

The method for manufacturing a pipe member whose end is closed according to any one of claims 1 to 8, wherein the method for manufacturing a pipe member is characterized by satisfying. The end according to any one of claims 1 to 9, wherein the time from the start of the mouth drawing molding until the manufactured pipe member is completely detached from the die is 10 s or less. A method for manufacturing a closed pipe member.

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