JP2019118942A - Metal spinning tool, method of manufacturing tapered metal pipe, and tapered metal pipe - Google Patents

Abstract

To provide a metal spinning tool, a method of manufacturing tapered metal pipe, and a tapered metal pipe manufactured thereby, which has an excellent production yield, has a reduced processing load, may form a tapered section at an excellent accuracy and an excellent production efficiency.SOLUTION: A metal spinning tool 1 comprises a distal part 3, a first taper part 4, and a second taper part 5. The distal part 3 is used for machining for narrowing the diameter of an end section of a metal pipe 2. The first taper part 4 extends to an end of the distal part 3 at the insertion side A of the metal pipe 2 and expands in diameter toward the insertion side A of the metal pipe 2. The second taper part 5 extends to a side B opposite to the insertion side A of the distal part 3 and expands in diameter toward the side B opposite to the insertion side A. The ratio of the length L of the distal part 3 and the outer diameter D of the metal pipe 2 meets with the following formula (1). L/D≤0.5 (1)SELECTED DRAWING: Figure 2

Description

  BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an aperture drawing tool, a method for producing an aperture metal tube, and an aperture metal tube. More particularly, the present invention relates to a drawing tool for drawing a pull, a method of manufacturing a drawing metal pipe, and a drawing metal pipe.

  One of the metal tubes is a seamless metal tube. The seamless metal pipe is manufactured as follows. First, the raw pipe is subjected to hot working such as Eugene method and Mannesmann method. Next, cold drawing is performed on the raw pipe. Thereby, a seamless metal pipe finished to a predetermined size is manufactured. In the following, seamless metal pipes are simply referred to as "metal pipes".

  The general drawing process is as follows. First, one end of the metal tube to be drawn is heated. "Tube end" means a partial area or the whole area up to 1/3 of the total length in the axial direction of the metal pipe from the pipe end. The heated tube end is pressed down to a shape that is easy to grip. The process of pressing down the end of the tube to make it thinner is called "squeezing process". Also, the end of the tube that has been made thin by the drawing process is referred to as the "mouth drawing part". The drawn metal tube is passed through a die. The outer peripheral surface of the mouth narrowing portion is gripped by the gripper. After gripping the mouth narrowing portion with the gripper, the gripper is moved in the drawing direction to pull out the metal tube from the die. A drawing process is implemented by the above process. After the drawing process, the mouth drawing portion is cut to obtain a product.

  The drawing process in which the outer peripheral surface of the mouth narrowing portion is gripped by the gripper is called grip drawing. In grip drawing, in order to secure the area which a gripper holds, a mouth narrowing part more than predetermined length is needed. Since the mouth constriction part is cut in a later step, if the mouth constriction part is long, the yield is lowered. Therefore, in grip drawing, it is desired to improve the yield.

  Grip drawing for improving the yield is disclosed, for example, in WO 2012/127557.

  Patent Document 1 discloses a device for drawing a grip and a method for drawing. In the case of one step of drawing the mouth, the mouth reduction portion does not have a uniform outer diameter. Therefore, in Patent Document 1, first, a parallel portion and an enlarged diameter portion are formed in the port constriction portion by one port constricting process. After the hole drawing process is performed once, the split mold is moved in the axial direction of the metal pipe by the retainer. After that, the mouth drawing process is performed. Under the present circumstances, the metal mold | die which processes a parallel part processes the enlarged diameter part of an aperture | diaphragm | squeeze part. By repeating this a plurality of times, a ported portion with a uniform outer diameter is formed. As a result, Patent Document 1 describes that the aperture does not become unnecessarily long and the yield is improved.

International Publication No. 2012/127557

  In grip drawing, it is necessary to secure the gripping area of the gripper, so there is a limit to the potential improvement in yield. Therefore, pull drawing is an alternative drawing process to grip drawing. In pull drawing, a pull rod is hooked on the inner circumferential surface of the mouth constriction portion to draw a metal pipe. Since the pull draw only pulls on the pull rod, the length of the draw head of the pull draw is shorter than that of the grip draw. Therefore, the yield can be improved by adopting a pull draw.

  However, when processing the draw-down portion for pulling draw, it is difficult to ensure the dimensional accuracy of the inner peripheral surface of the draw-out portion. If the dimensional accuracy of the inner peripheral surface of the mouth constriction portion is poor, it is difficult for the pull rod to pass through the inner peripheral surface of the mouth constriction portion. In addition, when processing the mouth drawing portion for drawing a pull with a conventional mouth drawing processing tool, the blank may move in the axial direction, and the processing efficiency is not high.

  An object of the present invention is a squeezing tool capable of forming a squeezed portion with high production efficiency with a reduced yield and reduced squeezing load, a method of manufacturing a squeezed metal tube, and a method of manufacturing the same It is providing an apertured metal tube.

The mouth drawing processing tool of the present embodiment is attached to the mouth drawing processing device, and the pipe end of the metal pipe is subjected to the drawing process. The mouth drawing processing tool includes a tip portion, a first tapered portion, and a second tapered portion. The front end portion squeezes the end of the metal pipe. The first tapered portion is connected to the end of the tip end of the metal tube on the insertion side, and the diameter is increased toward the insertion side of the metal tube. The second tapered portion is connected to the end of the tip end opposite to the insertion side of the metal pipe, and the diameter is increased toward the opposite side of the insertion side of the metal pipe. The ratio between the tip length L and the outer diameter D of the metal tube satisfies the equation (1).
L / D ≦ 0.5 (1)

  The method for manufacturing a drawn metal tube of the present embodiment includes a feeding step and a drawn step. In the feeding step, the metal tube is inserted into the mouth drawing processing apparatus including the above-described mouth drawing processing tool, and the pipe end of the metal pipe protrudes to the opposite side to the insertion side of the metal pipe than the tip of the mouth drawing processing tool Send a metal tube. In the squeezing process, the squeezing tool is moved along the diameter direction of the metal pipe, and the tip end squeezes the end of the metal pipe.

  The apertured metal tube of the present embodiment includes a tube end and an outer diameter D. The apertured metal tube is provided with a recess provided along the circumferential direction of the metal tube on the outer peripheral surface of the metal tube in the region from the tube end to 1.0 D along the axial direction of the metal tube.

  The manufacturing method of the squeezing tool and the squeeze metal tube according to the present invention can suppress the yield, reduce the squeezing load, and form the squeezed portion with high production efficiency with high accuracy. Moreover, the apertured metal tube according to the present invention can suppress the yield, and the accuracy of the apertured portion is high.

FIG. 1 is a perspective view showing a mouth drawing process. FIG. 2 is a cross-sectional view of the mouth drawing processing tool of the present embodiment. FIG. 3 is a cross-sectional view showing grip drawing. FIG. 4 is a cross-sectional view showing pull pulling. FIG. 5 is a cross-sectional view showing the manufacture of a general drawn metal tube for draw head drawing. FIG. 6 is a cross-sectional view showing a mouth drawing process by the mouth drawing processing tool of the present embodiment. FIG. 7 is a view showing the relationship between the taper angle of the first tapered portion and the diameter reduction ratio. FIG. 8 is a cross-sectional view of a drawing tool including a straight portion. FIG. 9 is a cross-sectional view of the apertured metal tube.

The mouth drawing processing tool of the present embodiment is attached to the mouth drawing processing device, and the pipe end of the metal pipe is subjected to the drawing process. The mouth drawing processing tool includes a tip portion, a first tapered portion, and a second tapered portion. The front end portion squeezes the end of the metal pipe. The first tapered portion is connected to the end of the tip end of the metal tube on the insertion side, and the diameter is increased toward the insertion side of the metal tube. The second tapered portion is connected to the end of the tip end opposite to the insertion side of the metal pipe, and the diameter is increased toward the opposite side of the insertion side of the metal pipe. The ratio of the length L of the tip to the outer diameter D of the metal tube satisfies the formula (1).
L / D ≦ 0.5 (1)

  In the mouth drawing processing tool of the present embodiment, the tip end first contacts with the metal pipe and is processed. As a result, the area of the end of the tube and the end that hits the tip is reduced (diameter reduction). On the other hand, a first tapered portion and a second tapered portion are provided on both sides of the tip portion. Therefore, while only the front end portion is processing the metal pipe, the area of the pipe end portion facing the first taper portion is expanded toward the insertion side of the metal pipe, and the pipe end portion facing the second taper portion The diameter of the region increases toward the opposite side to the insertion side of the metal tube. As a result, since the pipe end opens like a trumpet, the pipe end does not bend inside the metal pipe. Therefore, according to the mouth drawing processing tool of the present embodiment, the shape of the mouth drawing portion can be formed with high accuracy, and the pull rod can easily pass through the inside of the metal pipe.

  In addition, during the mouth drawing process, the tip end portion is sandwiched between the region facing the first tapered portion of the metal tube and the region facing the second tapered portion of the metal tube. Thereby, the metal pipe is difficult to move in the central axis direction during the drawing process. Therefore, the end of the tube can be drawn down with high accuracy.

  Furthermore, the metal squeeze tube manufactured by the squeeze tool according to the present embodiment is drawn by pull drawing. Therefore, as compared with the grip drawing, the length of the apertured portion is short, and the yield is improved. Further, as described later, even when the hole drawing process is performed a plurality of times, it is not necessary to send the metal pipe in the central axial direction as in general hole drawing, and the production efficiency is high.

  In the above-described aperture drawing tool, the taper angle α of the first tapered portion is preferably 35 degrees or more.

  If the taper angle α is 35 degrees or more, as described later, the first taper portion positively cuts the metal pipe even when the diameter reduction ratio by the aperture drawing is set to 20% or more suitable for actual operation. Do not process. Therefore, it is hard to produce the wrinkles by processing in the field of the tube end opposite to the 1st taper part.

  In the above-described aperture drawing tool, the taper angle β of the second tapered portion is preferably 10 degrees or more.

  If the taper angle β is 10 degrees or more, since the second tapered portion has a sufficient taper angle, the diameter of the region of the tube end facing the second tapered portion tends to increase in a trumpet shape. As a result, insertion of the pull rod is facilitated.

  The above-described mouth drawing processing tool may further include a straight portion connected to the end of the second tapered portion on the opposite side to the insertion side of the metal pipe.

  By including the straight portion on the side opposite to the insertion side of the second tapered portion, the outer diameter of the tube end can be easily drawn to a predetermined dimension or less.

  The method for manufacturing a drawn metal tube of the present embodiment includes a feeding step and a drawn step. In the feeding step, the metal tube is inserted into the mouth drawing processing apparatus including the above-described mouth drawing processing tool, and the pipe end of the metal pipe protrudes to the opposite side to the insertion side of the metal pipe than the tip of the mouth drawing processing tool Send a metal tube. In the squeezing process, the squeezing tool is moved along the diameter direction of the metal pipe, and the tip end squeezes the end of the metal pipe.

  In the method for manufacturing a drawn metal tube of the present embodiment, the above-described drawn tool is used. Therefore, the yield is suppressed, and the apertured portion can be formed with high accuracy. In order to reduce the processing load required for the mouth drawing, the end of the pipe before the mouth drawing may be preheated.

  The above manufacturing method may further include, after the step of drawing the opening, the step of drawing the pipe end of the metal pipe at the same position as the step of drawing the end in the axial direction of the metal pipe. Good.

  In this case, the amount of one hole drawing process is reduced. Therefore, even if it is a metal pipe of a material with low processability, it can be easily drawn.

In the step of feeding the metal tube, the ratio of the distance L1 from the tube end of the metal tube to the end on the insertion side of the second tapered portion of the aperture drawing tool and the outer diameter D of the metal tube is the equation (2) It is preferable to fill.
0.05 ≦ L1 / D (2)

  If L1 / D is less than 0.05, the region facing the second tapered portion of the metal pipe is short, so the region facing the second tapered portion is difficult to expand in a trumpet shape. However, if L1 / D is too large, the yield is lowered because the length of the end of the tube to be subjected to the port drawing process is long. Further, if L1 / D is too large, a high press load is required in order to squeeze a region close to the axial center of the metal pipe instead of the pipe end. Therefore, the upper limit of L1 / D is preferably 0.3.

  The above-described method for manufacturing a drawn metal tube may further include the step of heating the tube end of the metal tube before the step of feeding the metal tube.

  In this case, the drawing process is performed hot. Therefore, the processability of the pipe end portion is improved, and the hole drawing process is easy.

  An apertured metal tube manufactured by the above method for producing an apertured metal tube includes a tube end and an outer diameter D. The apertured metal tube is provided with a recess provided along the circumferential direction of the metal tube on the outer peripheral surface of the metal tube in the region from the tube end to 1.0 D along the axial direction of the metal tube.

  The mouth drawing processing tool of this embodiment is attached to a mouth drawing processing apparatus. A mouth-drawing tool squeezes the end of a metal pipe. The drawn metal tube is used for drawing processing by pull drawing. Based on the above, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings have the same reference characters allotted and description thereof will not be repeated.

[Aperture processing tool]
FIG. 1 is a perspective view showing a mouth drawing process. Referring to FIG. 1, the mouth drawing processing tool 1 is attached to a mouth drawing processing device (not shown). In FIG. 1, the case where eight mouth drawing processing tools 1 are attached to a mouth drawing processing apparatus is shown. The eight mouth drawing processing tools 1 are arranged at equal intervals around the central axis C of the mouth drawing processing apparatus. The tube end of the metal tube 2 is arranged to face the eight orifice drawing tools 8. Eight mouth drawing tools 1 move in the radial direction of the metal tube 2 and depress the tube end. Thereby, a mouth constriction part is formed.

  Here, when the mouth drawing processing tool 1 is attached to the mouth drawing processing device, the side into which the metal pipe 2 is inserted is referred to as "insertion side" (A in FIG. 1). The side where the metal pipe 2 is not inserted in the direction of the central axis C of the mouth drawing processing apparatus is referred to as "the opposite side to the insertion side" (B in FIG. 1).

[Tip]
FIG. 2 is a cross-sectional view of a mouth drawing processing tool. FIG. 2 shows a cross section along the central axis C of the mouth drawing device when the mouth drawing tool is attached to the mouth drawing device. Hereinafter, the “cross-section” means a cross-section along the central axis C of the mouth drawing processing apparatus.

  Referring to FIG. 2, the mouth drawing processing tool 1 includes a tip 3, a first taper 4, and a second taper 5. The tip 3 squeezes the end of the metal tube. When the mouth drawing processing tool 1 is attached to the mouth drawing processing device, the tip 3 is closest to the central axis C of the mouth drawing processing device as compared with other parts. Therefore, at the time of mouth drawing, the tip 3 contacts the metal pipe most quickly.

  The cross-sectional shape of the tip 3 includes a flat area. However, the cross-sectional shape of the tip 3 is not limited to this. The tip 3 may include two R-chamfered regions. One R-chamfered area is provided at the end of the insertion side A of the flat area. Another R-chamfered area is provided at the end of the flat area on the insertion side and the opposite side B. Moreover, the cross-sectional shape of the tip 3 may have a curvature in the entire area. The cross-sectional shape of the tip 3 may be flat over the entire area.

[First taper section]
The first tapered portion 4 is provided integrally with the distal end portion 3. The first tapered portion 4 is connected to the end of the tip portion 3 on the insertion side A of the metal tube. That is, when the mouth drawing processing tool 1 is attached to the mouth drawing processing device, the first tapered portion 4 is positioned closer to the insertion side A of the metal pipe than the distal end portion 3 in the central axis C direction of the mouth drawing processing device. The first tapered portion 4 is expanded in diameter toward the insertion side A of the metal pipe. Here, "diameter expansion" means that the distance from the central axis C of the mouth drawing device becomes long when the mouth drawing tool is attached to the mouth drawing device. That is, the first tapered portion 4 has a taper angle α in a cross sectional view. The taper angle α will be described later.

  The cross-sectional shape of the first taper portion 4 is constant. Therefore, when viewed from the central axis C direction of the mouth drawing processing device, the shape of the first taper portion 4 is an arc centered on the central axis C of the mouth drawing processing device.

[Second taper section]
The second tapered portion 5 is provided integrally with the distal end portion 3. The second tapered portion 5 is connected to the end of the tip portion 3 opposite to the insertion side B of the metal pipe. That is, when the mouth drawing processing tool 1 is attached to the mouth drawing processing device, the second tapered portion 5 is located on the opposite side B to the insertion side of the metal pipe than the tip 3 in the central axis C direction of the mouth drawing processing device Do. In summary, the mouth drawing processing tool 1 includes the first tapered portion 4, the tip end portion 3, and the second tapered portion 5 in order from the insertion side A of the metal pipe. The second tapered portion 5 is expanded in diameter toward the side B opposite to the insertion side of the metal pipe. That is, the second tapered portion 5 has a taper angle β in a cross sectional view. The taper angle β will be described later.

  The cross-sectional shape of the second tapered portion 5 is constant. Therefore, when viewed from the central axis C direction of the mouth drawing processing device, the shape of the second tapered portion 5 is an arc centered on the central axis C of the mouth drawing processing device.

[L / D]
The ratio between the length L of the tip and the outer diameter D of the metal tube satisfies the following formula (1). Here, the length L means a length along the central axis C direction of the mouth drawing processing device when the mouth drawing processing tool 1 is attached to the mouth drawing processing device. The outer diameter D of the metal tube means the outer diameter of the metal tube before the drawing process.
L / D ≦ 0.5 (1)

  If L / D is larger than 0.5, the length of the orifice portion is long, and the yield is not suppressed. In addition, if L / D is larger than 0.5, the length of the constriction part is unnecessarily long for pull drawing. On the other hand, if L / D is 0.5 or less, the length of the apertured portion is short, and the yield is suppressed. Further, as described above, in the pull drawing, it is sufficient if there is a length of the apertured portion on the inner circumferential surface of the metal pipe that is sufficient to hook the pull rod. Even if L / D is 0.5 or less, the length of the throttling portion for hooking the pull rod is sufficient.

  The lower limit of L / D is not particularly limited. This is because, even if L / D is small, it is possible to hook the pull rod by increasing the amount of drawing. That is, the amount of aperture reduction processing may be appropriately set in accordance with the value of L / D. Therefore, the lower limit of L / D should be greater than zero. However, in consideration of actual operation, L / D is preferably 0.02 or more.

[Control of yield]
FIG. 3 is a cross-sectional view showing grip drawing. Referring to FIG. 3, in the grip drawing, the gripper 10 holds the mouth narrowing portion 6. The gripper 10 is moved in the drawing direction indicated by the arrow. The metal pipe 2 is processed to a predetermined outer diameter by the die 8. In such a grip drawing, in order to secure the gripping area of the gripper 10, the length L2 of the mouth narrowing part needs to be a predetermined length or more. Therefore, the length of the aperture 6 is long. The mouth reduction part is cut and discarded after drawing processing. Therefore, if the length of the orifice portion 6 is long, the yield is lowered. Further, in order to be gripped by the gripper 10, the outer peripheral surface of the aperture stop 6 needs to be flat in a cross sectional view.

  FIG. 4 is a cross-sectional view showing pull pulling. Referring to FIG. 4, in pull pulling, the pull rod 7 is hooked on the inner circumferential surface of the mouth narrowing portion 6. The pull rod 7 is moved in a drawing direction indicated by an arrow to process the metal pipe 2 to a predetermined outer diameter. In pull drawing, it is only necessary to hook the pull rod 7 on the inner peripheral surface of the mouth drawing portion 6, and it is not necessary to grip the outer circumference of the mouth drawing portion 6 as in grip drawing. Therefore, the length L2 of the mouth constriction portion 6 is short as compared with the grip drawing. Therefore, the yield is suppressed.

  In the mouth drawing processing tool of the present embodiment, L / D is 0.5 or less. If L / D is 0.5 or less, grip drawing can not be performed because the length of the mouth narrowing portion is short. Moreover, the mouth-drawing processing tool of this embodiment is equipped with a tip part and two taper parts provided at both ends of the tip part. When the end portion of the tube is subjected to an end-drawing by such an end-drawing tool, the end portion does not become flat, and grip drawing can not be performed. That is, the metal drawing metal tube manufactured by the metal drawing tool of the present embodiment is processed by pull drawing. Therefore, according to the mouth drawing processing tool of the present embodiment, the yield can be suppressed. In addition, a "bore narrowing metal pipe" means a metal tube containing a port narrowing part.

[Machining accuracy]
FIG. 5 is a cross-sectional view showing the manufacture of a general drawn metal tube for draw head drawing. Referring to FIG. 5, a general tool 13 includes a tapered portion 11 and a flat portion 12. In the case of producing a drawn metal tube for draw draw, generally, the pressure is gradually reduced from the pipe end 9 of the metal tube 2 to form the drawn portion. Specifically, first, the tube end 9 of the metal tube is pressed down by the tool 13. Next, the tool 13 is separated from the metal tube 2, and the metal tube 2 is sent in the direction from the tapered portion 11 to the flat portion 12 of the tool 13. Thereafter, the tube end is machined again with a tool. Repeat this. At this time, the tapered portion 11 of the tool performs the drawing of the end of the tube. The reason is as follows.

  During mouth drawing, the part being processed receives a force F1 from the tool in the direction opposite to the feed direction of the metal tube. Therefore, the metal pipe 2 tries to move in the direction opposite to the feeding direction. If it processes by the taper part 11, this movement of a metal pipe can be suppressed. This is because the frictional force F2 is generated between the tapered portion 11 and the metal pipe 2 in contact with the tapered portion. The friction force F2 balances with the force F1 received by the metal pipe 2, whereby the metal pipe can be made to stand still and can be drawn.

  However, in such a general tool, the pipe end 9 bends and protrudes inside the metal pipe because the tapered portion performs the hole drawing process. The amount of protrusion of the tube end 9 into the metal tube depends on the material strength, the amount of processing, etc., so it is difficult to control the amount of protrusion of the tube end 9 into the metal tube. In pull drawing, a pull rod passes inside the metal pipe. If the tube end 9 projects inside the metal tube, the pull rod may not pass through the inside of the metal tube. On the other hand, according to the mouth drawing processing tool of this embodiment, the protrusion to the inside of the metal pipe of a pipe end can be suppressed.

  FIG. 6 is a cross-sectional view showing a mouth drawing process by the mouth drawing processing tool of the present embodiment. Referring to FIG. 6, in the mouth drawing processing tool 1 of the present embodiment, the tip 3 first contacts with the metal pipe 2 and is processed. Although it demonstrates by the below-mentioned manufacturing method, the pipe end 9 of the metal pipe 2 protrudes in the insertion side and opposite side B of the metal pipe rather than the front-end | tip part 3. As shown in FIG. Thus, the tip 3 processes a portion remote from the tube end 9. The area P3 that is in contact with the tip 3 is reduced (diameter reduction). On the other hand, both sides of the region in contact with the tip portion 3, that is, the region P1 facing the first taper portion 4 and the region P2 facing the second taper portion 5 are processed while processing the metal pipe 2 only at the tip portion 3 , Not restricted by the mouth drawing processing tool 1. Therefore, the diameter of the region P1 facing the first tapered portion 4 is increased toward the insertion side A of the metal tube, and the region P2 facing the second tapered portion 5 is expanded toward the opposite side B of the metal tube inserted side Diameter. Thus, the pipe end 9 does not protrude into the metal pipe because the pipe end 9 opens in a trumpet shape. In other words, the inner diameter D1 of the tube end 9 is larger than the inner diameter D2 of the area P3 to be processed at the tip end after the hole drawing processing by the port drawing processing tool 1 of the present embodiment. As described above, according to the mouth drawing processing tool 1 of the present embodiment, the shape of the mouth drawing portion can be formed with high accuracy, and the pull rod can easily pass through the inside of the metal pipe.

  In addition, during the squeezing process, the area P1 facing the first tapered portion 4 of the metal pipe expands toward the insertion side A of the metal pipe, and the area P2 facing the second tapered portion 5 of the metal pipe is the metal pipe The diameter increases toward the insertion side and the opposite side B of Therefore, the distal end portion 3 is sandwiched by a region P1 facing the first tapered portion of the metal pipe and a region P2 facing the second tapered portion of the metal pipe. Thus, the distal end portion 3 receives the force F3 from the region P1 facing the first taper portion, and the force F4 in the opposite direction to the force F3 received from the region P2 facing the second taper portion from the region facing the first taper portion Receive Since these two forces are balanced, it is difficult for the metal tube 2 to move in the central axis C direction during the drawing process. Therefore, the end of the tube can be drawn down with high accuracy.

  In addition, in the mouth drawing processing tool of the present embodiment, since L / D is 0.5 or less, the area in which the mouth drawing processing tool contacts the metal pipe is smaller than that of a general tool. Therefore, the press load applied to the mouth drawing processing tool may be small compared to a general tool. Moreover, according to the mouth drawing processing tool of this embodiment, it is not necessary to send the metal pipe in the central axis direction during the mouth drawing processing. As described above, the diameter of the region P1 facing the first tapered portion 4 increases in a trumpet shape toward the insertion side A. The pull rod can be hooked on the enlarged region P1. Therefore, even in the case of producing a drawn metal tube for drawing a draw, it is not necessary to send the metal tube in the direction of the central axis C as in general drawing, and the production efficiency is high.

[Taper angle α]
Referring to FIG. 2, the taper angle α of the first tapered portion is preferably 35 degrees or more, and more preferably 50 degrees or more. Here, the taper angle α means the angle between the surface of the first taper portion 4 and the central axis C of the aperture drawing device in cross section when the aperture drawing tool is attached to the aperture drawing device. . The same applies to the taper angle β of the second tapered portion described later.

  The present inventors investigated the effect of the taper angle α of the first tapered portion on the aperture drawing process by FEM (Finite Element Method). The various characteristics of the metal pipe supposing the mouth drawing process were made the same as the test steel pipe 2 of the Example mentioned later.

  FIG. 7 is a view showing the relationship between the taper angle of the first tapered portion and the diameter reduction ratio. Referring to FIG. 7, the vertical axis represents the taper angle α [°] of the first tapered portion, and the horizontal axis represents the outer diameter reduction ratio [%]. In order to carry out pull drawing, it is necessary to hook the pull rod 7 on the inner peripheral surface of the mouth narrowing portion 6 (see FIG. 4). Therefore, it is preferable that the outer diameter of the tube end be reduced by about 20 to 30% by the port drawing process. It can be seen from FIG. 7 that there is a correlation between the taper angle of the first tapered portion and the diameter reduction ratio. The diameter reduction ratio of 20% means that the taper angle of the first taper portion is about 35 degrees, and the diameter reduction ratio of 30% means that the taper angle of the first taper portion is about 50. Degrees. Therefore, the taper angle α of the first tapered portion is preferably 35 degrees or more, and more preferably 50 degrees or more. Also, this is due to the following reasons.

  As described above with reference to FIG. 6, when the tip end portion 3 squeezes the pipe end, the region P1 of the metal pipe 2 facing the first tapered portion 4 expands toward the insertion side A of the metal pipe. Diameter. That is, a region P <b> 1 facing the first tapered portion 4 of the metal pipe 2 approaches the first tapered portion 4. If the taper angle α of the first tapered portion is less than 35 degrees, the region P1 opposed to the first tapered portion easily contacts the first tapered portion 4. In other words, if the taper angle α of the first tapered portion is less than 35 degrees, the first tapered portion 4 processes the pipe end. At this time, slight wrinkles may occur in the region P1 opposed to the first tapered portion.

  The drawn metal tube is drawn in a later step. In the drawing process, the metal tube is passed through a die having an outer diameter smaller than the outer diameter of the metal tube to reduce the outer diameter. Therefore, if a metal pipe having a weir in the region P1 facing the first tapered portion 4 is subjected to a drawing process, the weir may extend over the entire central axis C direction of the drawn metal pipe. If the taper angle α of the first tapered portion is 35 degrees or more, the first tapered portion 4 does not easily come in contact with the metal pipe at the time of hole reduction processing. Even if the first tapered portion 4 contacts the metal pipe, the metal pipe is not positively processed if the taper angle α is 35 degrees or more. Therefore, wrinkles are less likely to occur in the region P1 facing the first tapered portion 4. As a result, even if drawing processing is performed, extension of the folds to the metal pipe is suppressed.

  However, the taper angle α of the first tapered portion in the present embodiment is not limited to 35 degrees or more. Even if the taper angle α is less than 35 degrees, wrinkles may not occur in the region P1 facing the first tapered portion 4 of the metal tube 2 depending on the material of the metal tube, the amount of hole drawing, etc. .

  The radial height of the metal pipe of the first tapered portion 4 is not particularly limited. The radial height of the metal pipe of the first taper portion 4 may be a height that can be formed such that the pull rod is hooked in the region P1 opposed to the first taper portion. Moreover, the length in the central axis C direction of the first taper portion 4 is not particularly limited. However, preferably, the length in the central axis C direction of the first tapered portion 4 is the same as the sum of the lengths in the central axis C direction of the tip 3 and the second tapered portion 5.

  Needless to say, the upper limit of the taper angle α of the first tapered portion is 90 degrees. In addition, the taper angle α may not be constant in the entire first taper portion 4. This is because a chamfer R is usually provided at the end of the first tapered portion 4. In this case, the taper angle α means the maximum taper angle of the first taper portion 4.

[Taper angle β]
The taper angle β of the second tapered portion is preferably 10 degrees or more. As described above, when the tip end portion 3 squeezes the pipe end portion, the diameter of the region P2 opposite to the second tapered portion 5 of the metal pipe 2 increases toward the side B opposite to the insertion side of the metal pipe. This prevents the tube end 9 from protruding inside the metal tube and facilitates the insertion of the pull rod.

  If the taper angle β of the second tapered portion is less than 10 degrees, the diameter P of the region P2 opposed to the second tapered portion is difficult to expand toward the side B opposite to the insertion side of the metal pipe because the taper angle β is small. Therefore, the pull rod may be difficult to insert. If the taper angle β is 10 degrees or more, since the second taper portion 5 has a sufficient taper angle, the diameter of the region P2 opposed to the second taper portion tends to increase in a trumpet shape. As a result, insertion of the pull rod is facilitated.

  However, the taper angle β of the second tapered portion in the present embodiment is not limited to 10 degrees or more. Even if the taper angle β is less than 10 degrees, the diameter of the region P2 opposed to the second tapered portion increases toward the side B opposite to the insertion side of the metal tube, depending on the material of the metal tube, the amount of hole reduction processing, etc. It is because there are cases.

  The radial height of the metal pipe of the second tapered portion 5 is not particularly limited. The radial height of the metal pipe of the second tapered portion 5 may be a height at which the diameter of the region P2 opposed to the second tapered portion can be increased.

  Needless to say, the upper limit of the taper angle β of the second tapered portion is 90 degrees. Further, the taper angle β may not be constant in the entire second taper portion 5. This is because a chamfer R is usually provided at the end of the second tapered portion 5. In this case, the taper angle β means the maximum taper angle of the second taper portion 5.

  FIG. 8 is a cross-sectional view of a drawing tool including a straight portion. Referring to FIG. 8, the mouth drawing processing tool 1 may include a straight portion 15. The straight portion 15 is connected to the end of the second tapered portion 5 on the side B opposite to the insertion side of the metal pipe. When the mouth drawing processing tool includes the straight portion, the outer diameter of the tube end 9 is reliably drawn down to a predetermined dimension or less. Therefore, it is possible to stably form the outer diameter of the tip of the mouth narrowing portion to be equal to or less than the inner diameter of the drawing die, and when drawing with drawing after drawing, the outer diameter of the pipe end becomes smaller than the inner diameter of the die, and the pipe end dies It can control that it becomes impossible to pass.

  Then, the manufacturing method of the apertured metal tube of this embodiment is demonstrated. The manufacturing method of the metal tube for drawing and drawing of the present embodiment uses a drawing apparatus equipped with the above-described drawing tool. The method for manufacturing a drawn metal tube of the present embodiment includes a feeding step and a drawn step.

[Feed process]
Referring to FIG. 1, in the feeding step, the metal pipe 2 is inserted into a not-shown port drawing device. Specifically, the metal pipe is placed on a conveyor, and the central axis of the metal pipe 2 is aligned with the central axis C of the drafting device. Thereafter, the metal tube is fed along the central axis C of the drafting device. The tube end faces the mouth drawing processing tool 1.

  Referring to FIG. 6, the metal pipe 2 is fed until the pipe end 9 projects to the side B opposite to the insertion side of the metal pipe from the tip 3 of the aperture drawing tool 1. Thereby, the front end portion 3 processes an area of a predetermined distance from the pipe end 9. As a result, as described above, the area P1 facing the first tapered portion 4 of the metal pipe 2 is expanded toward the insertion side A of the metal pipe, and the area P2 facing the second tapered portion 5 is the metal pipe The diameter increases toward the insertion side and the opposite side B.

The pipe end 9 of the metal pipe may project to the side B opposite to the insertion side B more than the tip 3 and the amount of the metal pipe to be fed is not particularly limited. However, preferably, the ratio L1 / D of the distance L1 from the pipe end 9 to the end of the insertion side A of the second tapered portion 5 to the outer diameter D of the metal pipe in the central axis direction of the mouth drawing processing apparatus is It is preferable to satisfy Formula (2) of
0.05 ≦ L1 / D (2)

  If L1 / D is less than 0.05 based on the embodiment described later, the region P2 facing the second tapered portion 5 of the metal pipe is short, so the region P2 facing the second tapered portion expands in a trumpet shape It is hard to make a diameter. If L1 / D is too large, the yield will be reduced because the length of the end of the tube to be subjected to port drawing is long. Further, if L1 / D is too large, a high press load is required in order to squeeze a region close to the axial center of the metal pipe instead of the pipe end. Therefore, the upper limit of L1 / D is preferably 0.3.

[Mouth drawing process]
Referring to FIG. 1, in the mouth drawing process, the mouth drawing tool 1 attached to the mouth drawing apparatus is moved along the diameter direction of the metal pipe. Thereby, the tip 3 squeezes the tube end. The mouth drawing device is, for example, a swaging device, a push pointer device, or a pressing device. In the case of drawing a metal tube having an outer diameter of 100 mm or more, a press is particularly preferable. The mouth drawing processing apparatus includes a pressure device such as a hydraulic cylinder. The pressurizing device brings the mouth drawing tool 1 closer to and away from the metal pipe along the diameter direction of the metal pipe. Thereby, the pipe end of the metal pipe is drawn by the drawing tool 1 to produce a drawn metal pipe. In addition, in the case of the port drawing process, the buffer plate 14 may be provided on the pipe end of the metal pipe opposite to the pipe end to be subjected to the port drawing process.

  According to the manufacturing method of the present embodiment, the yield is suppressed because the above-described aperture drawing processing tool is used. In addition, since the tube end of the one subjected to port drawing is difficult to protrude into the inside of the metal pipe, it is easy to insert the pull rod in the drawing process in the later step. In addition, after the feeding process, since the metal-drawn metal tube is manufactured in one hole drawing process, the production efficiency is high as compared with the conventional manufacturing method.

  The amount of drawing the tube end is not particularly limited. However, if the amount to be drawn is too large, there is a high possibility that wrinkles will occur in the area P1 to be machined by the first taper part, and therefore the material etc. of the metal pipe is considered to the extent that wrinkles do not occur. It is preferable to set the amount of drawing.

  The number of the mouth drawing processing tools 1 attached to the mouth drawing processing device is not particularly limited. The number of the mouth drawing processing tools 1 attached to the mouth drawing processing device may be two or more. Preferably, the plurality of mouth drawing processing tools 1 are arranged at equal intervals around the central axis C of the mouth drawing processing device.

  The mouth drawing of the tube end may be performed multiple times. By performing the mouth drawing process a plurality of times, the processing amount in one mouth drawing process can be reduced. Therefore, even if it is a material with low processability, it can be drawn. In this case, the second hole drawing process is performed after the above-described first hole drawing process. The second drawing process is similar to the first drawing process. However, the processing amount in the second drawing process may be different from the processing amount in the first drawing process.

  In addition, the metal pipe does not move along the central axis direction from the first hole drawing process to the second hole drawing process. That is, in the second hole drawing process, the tip end 3 of the metal pipe at the same position as the first drawing process in the central axis C direction is drawn. In the manufacturing method of the present embodiment, the above-described aperture drawing processing tool is used. Therefore, it is not necessary to squeeze the metal tube while feeding it in the central axis direction as in a general tool. However, the metal pipe 2 may be rotated around the central axis C in the second hole drawing process.

  In addition, there may be an opening reduction process three or more times. The third and subsequent mouth drawing processes are the same as the first and second times.

[Heating process]
The method for manufacturing a drawn metal tube of the present embodiment may include the step of heating the tube end of the metal tube before the step of feeding the metal tube. In the heating step, the tube end of the metal tube is heated. Although the method of heating is not particularly limited, it is usually performed by an induction heater, gas heating or the like. The metal pipe is, for example, a steel pipe. The heating temperature is, for example, 1100 degrees. As a result, since the hole drawing process is performed hot, the processability of the pipe end can be enhanced, the press load can be reduced, and the metal pipe of the difficult-to-process material can be subjected to the drawing process. Furthermore, it is possible to increase the amount of processing once.

[Aperture metal tube]
FIG. 9 is a cross-sectional view of the apertured metal tube. Referring to FIG. 9, when the above-described aperture drawing processing is completed, an apertured metal pipe 21 is obtained. The apertured metal tube comprises a tube end 9 and an outer diameter D. As described above, since the drawn metal tube of the present embodiment is subjected to pull drawing, the axial length L2 of the drawn portion is short. Specifically, the axial length L2 of the port reduction portion is equal to or less than the distance from the tube end 9 to the outer diameter D (L2 ≦ 1.0 D).

  The pipe end 9 opens in a trumpet shape by the above-described port drawing process. Seen from the tube end 9 along the axial direction of the metal tube, the bored metal tube includes a tube end 9, a reduced diameter portion 16, a bottom portion 17, an enlarged diameter portion 18, and a body portion 19. That is, the recessed part 20 is provided in the outer peripheral surface of a metal pipe. Further, as shown in FIG. 1, the hole reduction processing tool 1 is disposed along the circumferential direction of the metal pipe, and performs hole reduction processing on the entire circumferential direction of the end portion of the pipe. Therefore, the recess 20 is provided along the circumferential direction of the metal pipe. In other words, the cross section of the mouth constriction part is constant over the circumferential direction. In addition, the cross-sectional shape is not fixed strictly in accordance with the processing accuracy. Therefore, the constant cross-section referred to here means that the recess 20 is provided as shown in FIG. 9 in any cross-section of the apertured metal pipe.

  The minimum outer diameter of the recess 20, that is, the ratio D3 / D of the outer diameter D3 of the bottom 17 to the outer diameter D of the metal tube depends on the diameter reduction ratio of the hole drawing process. The upper limit of D3 / D is preferably 0.9 or less. If D3 / D is larger than 0.9, the amount of drawing by drawing is small, and it becomes difficult for the pull rod to be hooked during pull drawing. The lower limit of D3 / D is preferably 0.6 or more. If D3 / D is less than 0.6, the drawing amount is large, and the drawing rod is excessively drawn even though the pull rod is hooked. Also, if D3 / D is too small, when the pull rod is inserted from the end of the tube opposite to the drawn end, the rod will not pass easily. More preferably, the lower limit of D3 / D is 0.65 or more. More preferably, the lower limit of D3 / D is 0.7 or more.

  The pipe end portions of two types of metal pipes were subjected to a drawing process using the drawing process tool of the present embodiment.

[Test conditions]
In the present example, a drawing reduction process was performed on a test steel pipe 1 having the composition shown in Table 1 below and a test steel pipe 2 having the composition shown in Table 2 below. Referring to FIG. 6, in the step of feeding the metal pipe, the hole drawing was carried out by variously changing the distance L1 from the pipe end of the metal pipe to the end on the insertion side of the second tapered portion of the drawing tool.

  Subsequently, the drawing process conditions of the test steel pipe 1 will be described. The dimensions of the metal pipe and the drawing method were as shown in Table 3. Specifically, first, the tube end of the metal tube was heated to about 1100 degrees. Next, eight mouth drawing processing tools were attached to the press at equal intervals. The mouth drawing process was performed six times. The outer diameter of the orifice in Table 3 indicates nominal dimensions. In the six drawing processes, the processing amount in each drawing process was the same.

  The drawing conditions of the test steel pipe 2 will be described. Table 4 shows the dimensions of the metal tube and the drawing method. Specifically, first, the tube end of the metal tube was heated to about 700 degrees. Next, eight mouth drawing processing tools were attached to the press at equal intervals. The mouth drawing process was performed six times. The outer diameter of the orifice in Table 4 indicates nominal dimensions. In the six drawing processes, the processing amount in each drawing process was the same.

  In the drawing of the test steel pipe 1 and the test steel pipe 2, the dimensions of the drawing tool were the same. Table 5 shows the dimensions of the mouth drawing processing tool.

[Test results]
The test results of the test steel pipe 1 are shown in Table 6. The test results of the test steel pipe 2 are shown in Table 7. "G" in Table 6 and Table 7 means that mouth drawing was able to be implemented.

  Referring to Table 6, in the test steel pipe 1, when L1 / D is 0.11 or more, the length of the hole narrowing portion is sufficient, and the pull rod can be hooked on the inner circumferential surface of the hole narrowing portion .

  With reference to Table 7, in the test steel pipe 2, if L1 / D is 0.05 or more, the length of the hole narrowing portion is sufficient, and the pull rod can be hooked on the inner circumferential surface of the hole narrowing portion The On the other hand, if L1 / D is less than 0.05, in the step of feeding the metal tube, the amount of protrusion of the tube end to the side opposite to the insertion side is smaller than the tip of the hole drawing processing tool. Since it is thought that there is little carrying out actual operation in such a range, L1 / D did not test about less than 0.05.

  If L1 / D is too small, the area near the end of the pipe will be pressed down, and it will be difficult to open the pipe end like a trumpet due to the pressure reduction, but under the conditions where the diameter reduction ratio is smaller When the processing is carried out, there is a possibility that the hole drawing processing can be carried out even if L1 / D is 0.05.

  The embodiment of the present invention has been described above. However, the embodiments described above are merely examples for implementing the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented without departing from the scope of the invention.

1: Opening drawing tool 2: Metal pipe 3: Tip part 4: 1st taper part 5: 2nd taper part 6: 2nd opening part 7: Pull rod 8: Die 9: Tube end 14: Buffer plate

Claims (9)

A tool attached to a mouth drawing processing apparatus for drawing a pipe end of a metal pipe,
A tip end for drawing the end of the metal pipe;
A first tapered portion connected to an end of the tip end on the insertion side of the metal pipe and having a diameter increased toward the insertion side of the metal pipe;
And a second tapered portion connected to the end of the tip opposite to the insertion side of the metal pipe and having a diameter increased toward the opposite side of the insertion side of the metal pipe,
The aperture-drawing tool in which the ratio between the length L of the tip and the outer diameter D of the metal tube satisfies the formula (1).
L / D ≦ 0.5 (1) It is a mouth drawing processing tool according to claim 1,
The tapering tool according to claim 1, wherein a taper angle α of the first tapered portion is 35 degrees or more. It is a mouth narrowing processing tool according to claim 1 or claim 2, wherein
The taper angle β of the second tapered portion is 10 degrees or more. It is a mouth drawing processing tool according to any one of claims 1 to 3, and further,
A hole drawing processing tool, comprising: a straight portion connected to an end of the second tapered portion opposite to the insertion side of the metal pipe. A metal pipe is inserted into a mouth drawing processing apparatus including the mouth drawing processing tool according to any one of claims 1 to 4, and a pipe end of the metal pipe is the metal pipe rather than a tip end of the mouth drawing processing tool. Feeding the metal tube until it protrudes to the side opposite to the insertion side of
And moving the metal drawing tool along the diameter direction of the metal pipe, and drawing the metal tube at the tip end of the metal pipe. The method for producing a drawn metal tube according to claim 5, further comprising:
After the step of drawing, the step of drawing the tube end of the metal pipe at the same position as the step of drawing the tip in the axial direction of the metal pipe; Production method. A method of manufacturing a drawn metal tube according to claim 5, wherein
In the step of feeding the metal tube, the ratio of the distance L1 from the tube end of the metal tube to the end on the insertion side of the second tapered portion of the aperture drawing tool and the outer diameter D of the metal tube is Method of manufacturing a drawn metal tube, which satisfies).
0.05 ≦ L1 / D (2) A method for producing a metal tube for drawing an aperture according to any one of claims 5 to 7, further comprising:
A method of manufacturing a drawn metal tube, comprising the step of heating the tube end of the metal tube prior to the step of feeding the metal tube. An apertured metal tube comprising a tube end and an outer diameter D, wherein
An apertured metal pipe, comprising a recess provided along the circumferential direction of the metal pipe on the outer peripheral surface of the metal pipe in the region from the pipe end to 1.0 D along the axial direction of the metal pipe.

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