JP2009214154A - Bulging method and bulging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bulging method and a bulging device wherein prevention of leakage of pressured liquid, and high speed and high accuracy of tube expansion molding are attained and thereby the occurrence of variation of products is prevented. <P>SOLUTION: A rod 130 has a guide rod 131 and a hollow rod 132. The sealing part 140 on a side in the direction of forming is pressed toward the left end part of the hollow rod 132 by the liquid pressure of the pressure liquid L supplied between a tube stock 2 and the rod 130. Since the sealing part 40 is elastically deformed caused by being pressed by the pressure liquid L, the sealing part follows up the bulging of the tube stock 2. The hollow rod 132 controls the position of the sealing part 140 by its movement and, in such a case, the moving speed of the hollow rod 132 is controlled so as to be not lower than the bulging speed of the tube stock 2. The sealing part 150 on the opposite side in the direction of forming is fixed to the guide rod 131. The position of the sealing part 150 is not sifted or the shape is not changed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides bulge forming in which a compressive stress in the axial direction is applied to an element pipe disposed between a mold and a rod, and pressure is supplied into the element pipe to form the element pipe into the inner shape of the mold. The present invention relates to a method and a bulge forming apparatus, and more particularly to an improvement in a sealing method for sealing between a raw tube and a rod.

  A bulge forming method is applied to molding containers, processed tubes, and hollow structural parts of automobiles and various machines. In the bulge forming method, the raw pipe is formed into a desired shape by locally expanding and expanding the pipe without reducing the thickness. As a bulge forming tube obtained by this, a flexible tube that allows flexible bending of the bellows-shaped portion having a large number of bulged portions, and a bellows tube that performs heat dissipation using a feature that has a larger surface area than a normal tube There is a bellows tube that uses the shape of the bellows-like portion and has a spring-like elasticity function.

  In the bulge forming method, for example, a bulge forming apparatus 1 shown in FIG. 5 is used (see, for example, Patent Document 1). FIG. 5 is a side sectional view showing a schematic configuration of the bulge forming apparatus 1. In addition, in FIG. 5, the structure of the upper half of the bulge forming apparatus 1 is represented. For simplification of illustration, the position of the right end of the element tube 2 with respect to the mold 10 is the same in all drawings. The bulge forming apparatus 1 includes a mold 10 in which the raw tube 2 is disposed, and a butting mold 20 against which the left end portion of the raw tube 2 is abutted. The mold 10 and the abutment mold 20 are composed of a pair of upper mold and lower mold. The molds 10 and 20 are fixed by fixing means (not shown) for preventing them from being opened.

  The inner surface of the mold 10 has a bellows shape 11 in which a plurality of peak portions 11A and valley portions 11B are alternately formed. The peak portions 11A and the valley portions 11B are formed, for example, periodically and have an axially symmetrical shape. A rod 30 is provided inside the raw tube 2 so as to be movable along the axial direction thereof. A pressure liquid supply channel 31 is formed inside the rod 30, and the pressure liquid L is supplied from the raw tube 2 and the rod 30 through the pressure liquid supply port 31 </ b> A.

  A pair of grooves 32 and 33 are formed on the circumferential surface of the rod 30 with the pressure liquid supply port 31A therebetween. In the grooves 32, 33, a pair of ring-shaped seal portions 40, 50 that seal between the raw tube 2 and the rod 30 are disposed. A pressure liquid recovery channel (not shown) for recovering the pressure liquid L used for molding is formed on the left side of the seal portion 50 on the opposite side of the molding direction in the rod 30. The recovered pressure liquid L is supplied to the pressure liquid supply channel 31 and is reused. A movement mechanism (not shown) for moving the rod 30 to the right in the axial direction (molding direction side) is provided at the right end of the rod 30. On the right side of the mold 10, an element tube pressing mechanism (not shown) that applies compressive stress F to the element tube 2 toward the abutting mold 20 is provided.

  In the bulge forming apparatus 1, while applying compressive stress F from the right end portion to the left side in the axial direction (opposite side in the forming direction), the pressure fluid is applied to the raw tube 2 whose left end portion is abutted against the abutting mold 20. The pressurized liquid L is supplied between the raw tube 2 and the rod 30 from the supply port 31A. The pressure liquid L is set to a high pressure so that the base tube 2 can be deformed according to the peak portion 11 </ b> A of the bellows shape 11 of the mold 10, and the seal portions 40 and 50 are disposed between the base tube 2 and the rod 30. Is sealed. In such a state, each time the rod 30 is moved to the right in the axial direction and the pressure liquid L is supplied to a position corresponding to the peak portion 11A of the mold 10, the base tube 2 is moved to the peak portion by the high pressure liquid L. It bulges according to the shape of 11A. In this way, the base tube 2 is formed into a shape corresponding to the bellows shape 11 of the mold 10 by forming the crest 2A and the trough 2B one by one in order from the right side.

  However, in the pipe expansion molding by the bulge molding apparatus 1, the pressure liquid L is set to a high pressure for the expansion of the raw tube, so that the pressure liquid supply port 31 </ b> A of the mold 10 is formed after the first peak 2 </ b> A is molded. Whenever it moves between the mountain parts 11A and 11A, the following problems have arisen in the sealing performance by the seal parts 40 and 50.

  In pipe expansion molding, for example, as shown in FIG. 6 (A), a peak 2A is formed on the raw tube 2, and then the next peak (third peak) is formed as shown in FIG. 6 (B). When the rod 30 is moved in the direction of the arrow in the state in which the high pressure of the pressure liquid L is maintained as described above, the seal portion 40 on the molding direction side is the third portion in which the distance from the rod 30 in the mold 10 is large. Pass through the mountain 11A. At this time, since the raw tube 2 bulges according to the shape of the third peak portion 11A, the pressing force from the mold 10 is not easily applied to the sealing portion 40 on the molding direction side. As a result, the sealing performance by the first seal portion 40 is lowered, and there is a possibility that the pressurized liquid L leaks from the right outside. For this reason, in order to maintain the high pressure of the pressurized liquid L, it is necessary to increase the hydraulic pressure, and time loss occurs.

  On the other hand, when the seal part 50 on the opposite side in the molding direction passes through the first peak part 2A formed in the raw tube 2 as shown in FIG. 6B, the seal part 50 and the peak part 2A Since a large gap is formed between them, the pressure liquid L may leak out from there to the left side. For this reason, in order to maintain the high pressure of the pressurized liquid L, it is necessary to increase the hydraulic pressure, and time loss occurs. The above-described problem of airtightness due to the seal portions 40 and 50 occurs every time the pressurized liquid supply port 31A moves between the ridge portions 11A and 11A of the mold 10 after the first ridge portion 2A is formed.

  In addition, about the problem of the airtightness by the seal | sticker part 40 by the side of a shaping | molding direction, according to the position of the seal | sticker parts 40 and 50 with respect to the bellows shape 11 of the metal mold | die 10, the hydraulic pressure setting of the hydraulic fluid L is between high pressure and low pressure. Possible measures to switch.

  For example, after forming the first peak 2A as shown in FIG. 7A, the rod 30 is moved to the right in the axial direction (arrow in the figure) for forming the next peak as shown in FIG. 7B. Before moving in the direction), the pressure liquid L is set to a low pressure so that the raw tube 2 cannot be deformed. Subsequently, the pressure liquid supply port 31A arrives in the vicinity of the second peak portion 11A, and the seal portion 40 on the molding direction side arrives at the valley portion 11B adjacent to the right of the second peak portion 11A. Therefore, the seal portion 40 is held there. Next, as shown in FIG. 7C, the movement of the rod 30 is stopped, and the pressure liquid L is set to a high pressure, whereby the second peak portion 2 </ b> A is formed on the raw tube 2.

  Subsequently, as shown in FIG. 7 (D), the same operation as in FIG. 7 (B) is performed, the pressure of the pressure liquid L is lowered, and the pressure liquid supply port 31A is placed near the third peak portion 11A. Then, the seal portion 40 on the molding direction side is made to arrive at the valley portion 11B adjacent to the right side of the third peak portion 11A, thereby holding the seal portion 40 there. By switching between the high pressure and the low pressure of the hydraulic pressure setting of the pressure liquid L every time the peak portion 2A is molded and the pressure liquid supply port 31A is moved between the peak portions 11A and 11A, the molding direction side is changed. The problem of airtightness due to the seal part 40 is eliminated.

  However, in the hydraulic pressure setting of the hydraulic fluid L, it is necessary to repeatedly switch between high pressure and low pressure for expanding the raw tube 2, so it takes time to switch the hydraulic pressure, and high speed pipe expansion is performed. Difficult to do. Moreover, since the pressurized liquid L cannot always be kept at a high pressure, the shape freezing property of the base tube 2 to the mold 10 is lowered, and as a result, the accuracy of the tube expansion molding is lowered, and the product variation may increase. There is. In particular, when a bellows shape having a large number of peak portions 2A is formed on the raw tube 2, the problem is serious.

Japanese Patent Laid-Open No. 2001-321841

  Therefore, according to the present invention, it is possible not only to prevent the leakage of the pressurized liquid, but also to perform high-speed and high-accuracy tube expansion molding, thereby preventing the occurrence of product variations. An object is to provide a bulge forming method and a bulge forming apparatus.

  In the bulge forming method of the present invention, a raw pipe is disposed inside a mold having an inner surface shape in which a plurality of crests and troughs are alternately formed, and is fixed to the mold and has a pressure liquid supply port. A rod composed of a guide rod and a hollow rod arranged so as to be movable around the guide rod is provided inside the raw pipe, and a pair of seal portions for sealing between the raw pipe and the rod are supplied with pressurized liquid. Provided with an opening in between, one seal part is arranged so that the guide rod guides along the axial direction of the raw tube, and the other seal part is fixed to the guide rod, and the axial direction of the raw pipe is The compressive stress is applied to the inner tube of the die by moving the hollow rod in the axial direction while supplying the pressurized fluid into the elementary tube from the pressurized fluid supply port. One seal part is molded into a hollow rod with hydraulic pressure Thereby enabling follow the bulging of the blank tube by presses and elastically deforms toward the end of the countercurrent opposite, the position of one of the seal portion, and characterized by controlling the movement of the hollow rod.

  In the bulge forming method of the present invention, compressive stress in the axial direction is applied to the raw pipe, and the pressure liquid is supplied from the pressurized liquid supply port of the guide rod to the region in the raw pipe sealed by the pair of seal portions. Since the hollow rod is moved in the axial direction, each time the pressurized liquid is supplied to a position corresponding to the peak portion of the mold, the base tube bulges out according to the shape of the peak portion by the pressurized liquid. In this way, in the raw tube, the crest and trough are formed one by one in order from the opposite side of the hollow rod in the moving direction (opposite side of the forming direction), and expanded to a shape corresponding to the inner shape of the mold. Is done.

  Here, in the bulge forming method of the present invention, the pair of seal portions for sealing between the raw tube and the rod can be in close contact with the raw tube as follows. The seal part on one side (in the molding direction) is pressed toward the end opposite to the molding direction of the hollow rod by the hydraulic pressure supplied between the raw tube and the rod. The seal portion can follow the bulging of the raw tube by elastically deforming when pressed by the pressure liquid. Therefore, by appropriately setting the shape and elastic characteristics of the one seal part, the hydraulic pressure of the pressurized liquid, etc., at least a part of the one seal part can always be in close contact with the raw tube.

  In addition, since the position of one seal is controlled by the movement of the hollow rod, the movement speed of the hollow rod can be controlled to be equal to or higher than the bulging speed of the raw tube, so that one seal portion can be controlled. It can always be moved to the starting position of the bulge of the raw tube and to the molding direction side. Thereby, since one seal part is pressed by the edge part by the side of the shaping | molding direction of a hollow rod by the hydraulic pressure of the above pressurized liquids, the amount of elastic deformation becomes large. Therefore, it becomes easy to follow the bulging of the raw pipe of one seal part, and the adhesion to at least a part of the raw pipe of one seal part is further enhanced. As a result, even when the pressure liquid is always set to a high pressure during the molding of the raw tube, the leakage of the pressure liquid to the outside on the molding direction side can be prevented.

  In addition, since the other seal portion (on the opposite side in the molding direction) is fixed to the guide rod, the position of the seal portion is not slipped or changed in shape, and is positioned on the flat portion of the raw tube. Can do. Therefore, by appropriately setting the shape and elastic characteristics of the other seal portion, the seal portion can always be in close contact with the flat portion of the raw tube. As a result, even when the pressure liquid is always set to a high pressure during the molding of the raw tube, the leakage of the pressure liquid to the outside opposite to the molding direction can be prevented.

  As described above, according to the bulge forming method of the present invention, even if the pressure liquid is always set to a high pressure when forming the raw tube, leakage of the pressure liquid to the outside can be prevented. Therefore, it is not necessary to switch between the high pressure and the low pressure, so that the blank tube can be formed at a high pressure and at a high speed. In addition, since the pressurized liquid can be kept at a high pressure at all times, the shape freezing property of the raw pipe to the mold is improved, and as a result, the accuracy of the tube expansion molding is improved and the occurrence of product variations can be prevented. it can.

  In addition, since the hollow rod that moves during the forming of the raw tube receives the hydraulic pressure only from the end opposite to the molding direction via one seal part, the entire outer peripheral surface of the rod receives the hydraulic pressure compared to the conventional case. The hydraulic pressure received by the hollow rod is reduced. Thereby, since the force required for position control of the hollow rod can be reduced, the moving mechanism of the hollow rod can be reduced in size. Furthermore, since the pressure liquid supply port is formed in the guide rod fixed to the mold, the pressure liquid supply path to the pressure liquid supply port can be formed in the guide rod. Therefore, the pressure liquid supply path can be easily configured as compared with the conventional case in which the pressure liquid supply path is formed in the rod that moves when the raw tube is formed. From the above, the cost can be reduced.

  Various configurations can be used in the bulge forming method of the present invention. For example, the guide rod is composed of a large-diameter portion and a small-diameter portion that is formed integrally with the large-diameter portion and has a smaller diameter than the large-diameter portion, and the large-diameter portion fixes the other seal portion, The part can guide one seal part in the axial direction of the raw tube, dispose the hollow rod so as to be movable around the small diameter part, and form the pressurized liquid supply port in the large diameter part. In this aspect, since the pressure liquid supply port is formed in the large diameter portion of the guide rod, one seal portion at the start of forming the raw tube can be abutted against the end portion of the large diameter portion on the small diameter portion side. Therefore, it is possible to easily position the initial position of one of the seal portions when starting the blank tube forming.

  The bulge forming method of the present invention can be applied to a bulge forming apparatus. That is, the bulge forming apparatus of the present invention has an inner surface shape in which a plurality of crests and troughs are alternately formed, a mold in which a raw pipe is disposed, and a rod provided in the raw pipe And a pair of seal portions for sealing between the raw tube and the rod, and the rod is fixed to the mold and has a pressure liquid supply port. It is composed of a guide rod and a hollow rod arranged so as to be movable around the guide rod, and one seal portion is arranged so as to be guided by the guide rod along the axial direction of the raw tube, and the other seal The tube is fixed to the guide rod, compressive stress in the axial direction is applied to the raw pipe, and the hollow rod is moved in the axial direction while supplying the pressurized liquid into the raw pipe from the pressurized liquid supply port. To the inner shape of the mold When forming the blank tube, one of the seals is pressed against the end of the hollow rod opposite to the molding direction with the pressure of the hydraulic fluid and elastically deformed to follow the expansion of the blank tube. In addition, the position of one seal portion is controlled by the movement of the hollow rod. The bulge forming apparatus of the present invention can obtain the same actions and effects as the above bulge forming method.

  The bulge forming apparatus of the present invention can use various configurations. For example, the guide rod is composed of a large-diameter portion and a small-diameter portion that is formed integrally with the large-diameter portion and has a smaller diameter than the large-diameter portion. The large-diameter portion fixes the other seal portion, and the small-diameter portion Can be configured such that one seal portion is guided in the axial direction of the raw tube, the hollow rod is disposed so as to be movable around the diameter portion, and the pressurized liquid supply port is formed in the large diameter portion. In this aspect, the same actions and effects as in the aspect of the bulge forming method can be obtained.

  According to the bulge forming method or the bulge forming apparatus of the present invention, even if the pressure liquid is always set to a high pressure when forming the raw pipe, it is possible to prevent leakage of the pressure liquid to the outside. Therefore, it becomes unnecessary to switch between high pressure and low pressure, so that the raw tube can be formed at high pressure and at high speed. In addition, since the pressurized liquid can be kept at a high pressure at all times, the shape freezing property of the raw pipe to the mold is improved, and as a result, the accuracy of the tube expansion molding is improved and the occurrence of product variations can be prevented. The effect that it can do is acquired.

(A) First embodiment
(1) Configuration of Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing a schematic configuration of a bulge forming apparatus 100 according to the first embodiment of the present invention. In the first embodiment, the same components as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted.

  A rod 130 is provided inside the raw tube 2 along the axial direction thereof. The rod 130 includes a guide rod 131 that is fixed to the raw tube 2 and a hollow rod 132 that is movably disposed around the guide rod 131. The guide rod 131 has a large diameter portion 131A and a small diameter portion 131B having a smaller diameter than the large diameter portion 131A. The left end portion of the large diameter portion 131 </ b> A is fixed to the abutting die 20. The small diameter portion 131B is integrally formed with the right end portion of the large diameter portion 131A and extends to the right in the axial direction. The hollow rod 132 is disposed between the raw tube 2 and the small diameter part 131B, and can slide in contact with the small diameter part 131B.

  A pressure liquid supply flow path 133 is formed inside the rod 130 and the abutting mold 20, and the pressure liquid L is supplied from the raw tube 2 and the rod 130 through the pressure liquid supply port 133 </ b> A therefrom. The pressurized fluid supply port 133A is formed on the surface of the small diameter portion 131B. In the first embodiment, it is not necessary to recover the pressure liquid L as described below at the time of tube expansion molding, and therefore it is not necessary to provide a pressure liquid recovery flow path. A groove 134 is formed on the circumferential surface of the large-diameter portion 131B.

  Between the raw tube 2 and the rod 130, a seal part 140 (one seal part) and a seal part 150 (the other seal part) are arranged to seal them. The seal portion 140 has a ring shape and is arranged so as to be slidable on the circumferential surface of the small diameter portion 131B. The seal parts 140 and 150 have elasticity. In the first embodiment, since the moving direction of the hollow rod 132 at the time of forming the raw tube 2 is the right side, the seal part 140 is a seal part on the molding direction side, and the seal part 150 is a seal part on the opposite side in the molding direction.

  The seal portion 140 is elastically deformed by being pressed toward the left end portion of the hollow rod 132 by the hydraulic pressure of the pressurized liquid L supplied between the raw tube 2 and the rod 130, and the position of the seal portion 140 is the hollow rod. Controlled by movement of 132. Such a seal portion 140 is compressed in the axial direction and expanded in the vertical direction by the pressure liquid L, so that it can follow the expansion of the raw tube 2. In this case, since the seal portion 140 is disposed at the left end portion of the hollow rod 132 that is the start position of the bulge of the raw tube 2, it is easy to follow the bulge of the raw tube 2 of the seal portion 140. . In this case, by appropriately setting the shape and elastic characteristics of the seal part 140, the hydraulic pressure of the pressurized liquid L, the moving speed of the hollow rod 132, etc., at least a part of the seal part 140 is always in close contact with the raw tube 2. be able to. The initial position of the seal portion 140 is set to the position of the valley portion 11B between the first peak portion 11A and the second peak portion 11A in the mold 10 by the left end portion of the hollow rod 132, for example. . The seal portion 140 may be fixed to the left end portion of the hollow rod by adhesion or the like.

  The seal portion 150 has a ring shape and is fixed to the groove 134. In this case, by appropriately setting the shape and elastic characteristics of the seal portion 150, the seal portion 150 can always adhere to the flat portion at the left end portion of the raw tube 2.

(2) Operation of Embodiment Next, a bulge forming method by the bulge forming apparatus 100 will be described mainly with reference to FIG.

  As shown in FIG. 2, the pair of seal portions 140 and 150 are applied while the left end portion of the element tube 2 is abutted against the abutting mold 20 and compressive stress F is applied from the right end portion of the element tube 2 to the left in the axial direction. The pressurized liquid L is supplied into the raw tube 2 from the pressurized liquid supply port 133A to the region sealed by the above. By moving the hollow rod 132 to the right in the axial direction (in the direction of the arrow in the figure) in this state, each time the pressurized liquid L is supplied to the position corresponding to the peak portion 11A of the mold 10, the base tube 2 is pressurized. L bulges out according to the shape of the peak 11A. In this way, the peak 2A and the valley 2B are formed in the raw tube 2 one by one in order from the opposite side of the movement direction of the hollow rod 132 (the opposite side of the molding direction). The tube is formed into a shape corresponding to the bellows shape 11.

  In such tube expansion molding, the sealing portion 140 on the molding direction side is pressed toward the left end portion of the hollow rod 132 by the hydraulic pressure of the pressurized liquid L supplied between the raw tube 2 and the rod 130. Therefore, the seal portion 140 on the molding direction side can follow the swelling of the raw tube 2 by being elastically deformed by pressing with the pressure liquid L. Therefore, by appropriately setting the shape and elastic characteristics of the sealing portion 140 on the molding direction side, the hydraulic pressure of the pressure liquid L, etc., at least a part of the sealing portion 140 on the molding direction side is always in close contact with the raw tube 2. be able to.

  Further, since the hollow rod 132 controls the position of the seal portion 140 on the molding direction side by its movement, the movement speed of the hollow rod 132 can be controlled to be equal to or higher than the bulging speed of the raw tube 2. Thus, the sealing portion 140 on the molding direction side can always be moved to the starting position of the expansion of the raw tube 2 and to the molding direction side. As a result, the sealing portion 140 on the molding direction side is pressed at the left end portion of the hollow rod 132 by the hydraulic pressure of the pressure fluid L as described above, and thus the amount of elastic deformation increases. Therefore, it becomes easy to follow the bulging of the raw tube 2 of the sealing portion 140 on the molding direction side, and the adhesion to at least a part of the raw tube 2 of the sealing portion 140 on the molding direction side is further enhanced. As a result, even when the pressure liquid L is always set to a high pressure when the raw tube 2 is formed, leakage of the pressure liquid L to the outside on the molding direction side can be prevented.

  On the other hand, since the seal portion 150 on the opposite side in the molding direction is fixed to the guide rod 131, the position of the seal portion 150 does not slip or change in shape, and is positioned at the flat portion of the raw tube 2. be able to. Therefore, by appropriately setting the shape and elastic characteristics of the seal portion 150 on the opposite side in the molding direction, the seal portion 150 can always be in close contact with the flat portion of the raw tube 2. As a result, even when the pressure liquid L is always set to a high pressure when the raw tube 2 is formed, leakage of the pressure liquid L to the outside on the side opposite to the forming direction can be prevented.

  As described above, in the first embodiment, even when the pressure liquid L is always set to a high pressure when the raw tube 2 is formed, leakage of the pressure liquid L to the outside can be prevented. Since it is not necessary to make up or switch the hydraulic pressure between a high pressure and a low pressure, the raw tube 2 can be molded at a high pressure and at a high speed. In addition, since the pressurized liquid L can be maintained at a high pressure at all times, the shape freezing property of the raw tube 2 to the mold 10 is improved, and as a result, the accuracy of the tube expansion molding is improved and the occurrence of product variations is prevented. can do.

  Further, since the hollow rod 132 that moves when the raw tube 2 is molded receives the hydraulic pressure only from the left end portion via the sealing portion 140 on the molding direction side, the entire outer peripheral surface of the rod receives the hydraulic pressure as compared with the conventional case. The hydraulic pressure received by the hollow rod 132 is reduced. Thereby, since the force required for position control of the hollow rod 132 can be reduced, the moving mechanism of the hollow rod 132 can be downsized. Further, since the pressurized fluid supply port 133A is formed in the guide rod 131 fixed to the abutting die 20, the pressurized fluid supply path 133 to the pressurized fluid supply port 133A is formed in the guide rod 131. Can do. Therefore, the pressure liquid supply path 133 can be easily configured as compared with the conventional case in which the pressure liquid supply path is formed in the rod that moves when the raw tube is formed. From the above, the cost can be reduced.

(B) Second Embodiment FIG. 3 is a side sectional view showing a schematic configuration of a bulge forming apparatus according to a second embodiment of the present invention. In the second embodiment, components similar to those in the first embodiment are denoted by the same reference numerals, and descriptions of components having the same functions as those in the first embodiment are omitted. In the second embodiment, the pressurized fluid supply port 133 </ b> A is formed on the surface of the large diameter portion 131 </ b> A of the guide rod 131 instead of being formed on the surface of the small diameter portion 131 </ b> B of the guide rod 131. Thereby, the seal part 140 on the molding direction side at the start of molding of the raw tube 2 can be abutted against the right end part of the large diameter part 131A. Therefore, the initial position of the seal portion 140 on the molding direction side when starting the blank tube molding can be easily performed.

  In such a second embodiment, from the state where the initial position of the seal portion 140 on the molding direction side is set as described above, by performing the blank tube molding similar to the first embodiment as shown in FIG. The same operations and effects as those of the first embodiment can be obtained.

It is a sectional side view showing a schematic structure of a bulge forming device concerning a 1st embodiment of the present invention. It is a sectional side view showing the process of the bulge forming method using the bulge forming apparatus shown in FIG. It is a sectional side view showing a schematic structure of a bulge forming device concerning a 2nd embodiment of the present invention. It is a sectional side view showing the process of the bulge forming method using the bulge forming apparatus shown in FIG. It is a sectional side view showing the schematic structure of the conventional bulge forming apparatus. Each step of the bulge forming method using the bulge forming apparatus of FIG. 5 is represented, (A) is a side sectional view showing a schematic configuration of the bulge forming apparatus immediately after forming the second peak portion of the raw tube, (B). These are sectional side views showing the schematic structure of the bulge forming apparatus when the rod is moved for forming the third peak. Each step of another bulge forming method using the bulge forming apparatus of FIG. 5 is represented, (A) is a side sectional view showing a schematic configuration of the bulge forming apparatus immediately after forming the first peak portion of the raw tube, B) is a side sectional view showing a schematic configuration of the bulge forming apparatus before forming the second crest of the element pipe, and (C) is an outline of the bulge forming apparatus immediately after forming the third crest of the element pipe. A side sectional view showing composition, (D) is a side sectional view showing a schematic structure of a bulge forming device before forming the 3rd peak part of a blank tube.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Elementary tube, 10 ... Mold, 11 ... Bellows shape (inner surface shape), 11A ... Mountain part, 11B ... Valley part, 20 ... Abutment mold (mold), 100 ... Bulge forming apparatus, 130 ... Rod, 131 ... Guide rod, 132 ... Hollow rod, 133A ... Pressure liquid supply port, 140 ... Seal part on the molding direction side (one seal part), 150 ... Seal part on the opposite side in the molding direction (other seal part), L ... Pressure fluid

Claims (4)

Arranging the raw pipe inside the mold having an inner surface shape in which a plurality of peaks and valleys are alternately formed,
A rod composed of a guide rod that is fixed to the mold and has a pressure liquid supply port, and a hollow rod that is movably disposed around the guide rod is provided inside the element tube,
A pair of seal portions for sealing between the raw tube and the rod is provided with the pressure liquid supply port therebetween, and one guide portion is guided by the guide rod along the axial direction of the raw tube. And fixing the other seal part to the guide rod,
The hollow pipe is moved in the axial direction while applying the compressive stress in the axial direction to the raw pipe, and supplying the pressurized liquid into the raw pipe from the pressurized liquid supply port, thereby moving the hollow pipe in the axial direction. To the inner shape of
At the time of forming the raw tube, the one seal part is pressed toward the end of the hollow rod opposite to the forming direction by the hydraulic pressure to be elastically deformed, thereby expanding the raw tube. A bulge forming method characterized in that it can follow and the position of the one seal part is controlled by the movement of the hollow rod. The guide rod is composed of a large-diameter portion and a small-diameter portion that is formed integrally with the large-diameter portion and has a smaller diameter than the large-diameter portion,
The large-diameter portion fixes the other seal portion,
The small diameter portion guides the one seal portion in the axial direction of the raw pipe,
The hollow rod is disposed so as to be movable around the small diameter portion,
The bulge forming method according to claim 1, wherein the pressurized liquid supply port is formed in the large diameter portion. It has an inner surface shape in which a plurality of crests and troughs are alternately formed, and a mold in which a raw pipe is arranged, a rod provided inside the raw pipe, and the pressurized liquid supply port And a pair of seal portions for sealing between the raw tube and the rod,
The rod is composed of a guide rod that is fixed to the mold and has the pressure liquid supply port, and a hollow rod that is movably disposed around the guide rod,
One seal part is arranged so as to be guided by the guide rod along the axial direction of the raw tube, and the other seal part is fixed to the guide rod,
The hollow pipe is moved in the axial direction while applying the compressive stress in the axial direction to the raw pipe, and supplying the pressurized liquid into the raw pipe from the pressurized liquid supply port, thereby moving the hollow pipe in the axial direction. To the inner shape of
At the time of forming the raw tube, the one seal part is pressed toward the end of the hollow rod opposite to the forming direction by the hydraulic pressure to be elastically deformed, thereby expanding the raw tube. A bulge forming apparatus characterized by being capable of following and controlling the position of the one seal part by movement of the hollow rod. The guide rod is composed of a large-diameter portion and a small-diameter portion that is formed integrally with the large-diameter portion and has a smaller diameter than the large-diameter portion,
The large-diameter portion fixes the other seal portion,
The small diameter portion guides the one seal portion in the axial direction of the raw pipe,
The hollow rod is arranged to be movable around the small diameter portion,
The bulge forming apparatus according to claim 3, wherein the pressurized liquid supply port is formed in the large diameter portion.

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