Water expansion forming device

Abstract

The utility model discloses a water expansion forming device. The water expansion forming device comprises an upper die and a lower die, the lower die and the upper die are combined to form a water expansion forming cavity, a first clearance position and a second clearance position, the first clearance position and the second clearance position are communicated with openings in the two sides of the water expansion forming cavity respectively, and a containing space capable of containing a screw head is formed in the position, close to the water expansion forming cavity, of the first clearance position; the first punching needle extends into the containing space through the first receding position, a first near-end shaft shoulder is arranged at the end of the first punching needle, a far-end shaft shoulder is arranged at the position, away from the end, of the first punching needle, and the size of the far-end shaft shoulder is larger than that of the first near-end shaft shoulder; the second punching needle extends into the water expansion forming cavity through the second clearance position, and a second near-end shaft shoulder is arranged at the end part of the second punching needle; and an injection channel is arranged in the first punching needle or the second punching needle. By means of the water expansion forming device, the stainless steel pipe joint with the screw head can be directly machined, and the requirement of an engineering project is met.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of pipe processing, particularly to a water swelling forming device. BACKGROUND

[0002] In the drinking water project, compared with the plastic water pipe, the thin-walled stainless steel water pipe has many technical advantages in addition to the cost. The thin-walled stainless steel water pipe has high strength and good impact resistance, its external impact resistance is 8 to 10 times that of the plastic water pipe, and it has superior corrosion resistance, its internal and external oxide films can withstand high concentration of chloride content, effectively resist rusting, corrosion and other problems, and stainless steel is a healthy material that can be implanted in the human body, non-toxic and harmless, will not cause secondary pollution to the water quality, meet the national direct drinking water quality standards. In addition, the thin-walled stainless steel water pipe can adopt various connection modes such as clamping and pressing, ring pressing and groove type, avoiding environmental pollution and health hazards caused by glue bonding, effectively improving the installation efficiency of the project and the quality of drinking water.

[0003] At present, the parts of the thin-walled stainless steel water pipe at least include a stainless steel pipe, a straight pipe joint and an elbow pipe joint. For the machining of the straight pipe joint and the elbow pipe joint, the water swelling forming device and forming process disclosed in the publication No. CN112808836A can be referred to. The water swelling forming device is used for water swelling forming machining, and the production efficiency is much higher than that of the traditional machining process.

[0004] According to customer feedback, in order to meet the needs of engineering projects, a screw head needs to be arranged at one end of the stainless steel pipe joint, so as to directly install the faucet and other accessories with external threads. However, in the prior art, there is no water swelling forming device matched therewith. UTILITY MODEL CONTENTS

[0005] The utility model aims to provide a water swelling forming device which can perform water swelling forming on a pipe blank with a screw head at one end, and can prevent the internal threads of the screw head from being impacted by ultra-high water pressure.

[0006] The water swelling forming device according to the first aspect of the utility model comprises:

[0007] an upper die;

[0008] a lower die which forms a water swelling forming cavity, a first air avoiding position and a second air avoiding position with the upper die, the first air avoiding position and the second air avoiding position are respectively communicated with two side openings of the water swelling forming cavity, and the first air avoiding position is provided with a containing space capable of containing a screw head at a position close to the water swelling forming cavity;

[0009] A first punch needle extends into the accommodation space through the first avoiding position, and an end of the first punch needle is provided with a first proximal end shoulder, and the first punch needle is provided with a distal end shoulder at a position away from the end, and the size of the distal end shoulder is greater than the size of the first proximal end shoulder;

[0010] A second punch needle extends into the water swelling forming cavity through the second avoiding position, and an end of the second punch needle is provided with a second proximal end shoulder, and the first punch needle or the second punch needle is internally provided with an injection channel.

[0011] According to the water swelling forming device, the pipe fitting blank with the screw head is first placed on the lower die, at this time, the position of the screw head is located at the corresponding position of the accommodation space, then the upper die moves towards the lower die and performs die closing, after that, the first punch needle gradually extends into the first avoiding position until the first proximal end shoulder of the first punch needle is sealed and abuts against the narrowed position between the pipe fitting blank and the screw head, at this time, the distal end shoulder of the first punch needle also abuts against the outer side end face of the screw head, at the same time, the second punch needle gradually extends into the second avoiding position until the second proximal end shoulder of the second punch needle is sealed and abuts against the pipe opening of the pipe fitting blank, because the narrowed position between the pipe fitting blank and the screw head is sealed by the first proximal end shoulder of the first punch needle and the other end of the pipe fitting blank is sealed by the second proximal end shoulder of the second punch needle, therefore, the inside of the pipe fitting blank can be kept sealed during the water swelling forming process, the high-pressure liquid cannot enter the thread segment of the screw head from the injection channel, so that the internal thread of the screw head is prevented from being deformed due to the impact of the super-high water pressure, and the setting of the distal end shoulder can limit the position of the screw head and prevent the connection part of the screw head and the pipe fitting blank from being broken under the impact of the super-high water pressure, through the above water swelling forming device, the stainless steel pipe joint with the screw head can be directly processed to meet the needs of engineering projects.

[0012] According to some embodiments of the present application, the first punch needle is internally provided with an injection channel.

[0013] According to some embodiments of the present application, the first punch needle comprises a fixed part and a movable part, the movable part is movably nested in the fixed part, the movable part and the fixed part are both provided with the injection channel, the first proximal end shoulder is arranged on the movable part, and the distal end shoulder is arranged on the fixed part. Through such a setting, the first proximal end shoulder and the distal end shoulder of the first punch needle can relatively move to meet different working conditions.

[0014] According to some embodiments of the present application, specifically, the outer circumferential surface of the movable part is provided with a plurality of sliding grooves arranged in the axial direction, and the fixed part is provided with a sliding block slidingly connected to the sliding grooves.

[0015] According to some embodiments of the utility model, in order to avoid the leakage of high pressure water from the connecting position between the movable part and the fixed part during the water swelling forming process, the chute is provided with a sealing element between one end close to the fixed part and the sliding block.

[0016] According to some embodiments of the utility model, in order to realize the guiding of the upper die, the upper die is connected with at least two guide columns, and the lower die is provided with guide holes corresponding to the guide columns.

[0017] According to some embodiments of the utility model, in order to realize the positioning of the upper die, the upper die is connected with a plurality of positioning columns, and the lower die is provided with positioning holes corresponding to the positioning columns.

[0018] According to some embodiments of the utility model, the number of water swelling forming cavities is multiple, and the number of water swelling forming cavities determines the number of products formed by the mold in one machining process.

[0019] According to some embodiments of the utility model, the two side openings of the water swelling forming cavity have intersecting central axes, and at this time, the water swelling forming cavity is used for forming a bend pipe joint.

[0020] According to some embodiments of the utility model, the two side openings of the water swelling forming cavity have coaxial central axes, and at this time, the water swelling forming cavity is used for forming a straight pipe joint.

[0021] The additional aspects and advantages of the utility model will be partially given in the following description, some will become obvious from the following description, or be understood through the practice of the utility model. BRIEF DESCRIPTION OF DRAWINGS

[0022] The above and / or additional aspects and advantages of the utility model will become apparent and more readily appreciated from the following description of the embodiments, with reference to the following drawings, in which:

[0023] Figure 1 is the half sectional view of the water swelling forming device provided by the utility model embodiment;

[0024] Figure 2 is the structural schematic view of the lower die provided by the utility model embodiment;

[0025] Figure 3 is the half sectional view of the first punch pin and the second punch pin provided by the utility model embodiment.

[0026] In the drawings: 100 - lower die, 110 - hydroforming cavity, 120 - first avoidance position, 130 - second avoidance position, 140 - guide hole, 150 - positioning hole, 210 - screw head, 200 - elbow blank, 121 - accommodation space, 300 - first punch pin, 400 - second punch pin, 500 - power device, 330 - injection channel, 510 - injection chamber, 321 - first proximal shaft shoulder, 311 - distal shaft shoulder, 421 - second proximal shaft shoulder, 220 - narrowing position, 310 - fixed part, 320 - movable part, 312 - groove, 323 - sliding groove, 313 - sliding block, 331 - gap, 322 - sealing element. DETAILED DESCRIPTION

[0027] The embodiments of the present application are described in detail below, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are used only for explaining the present application, and cannot be understood as a limitation of the present application.

[0028] In the description of the present application, it should be understood that, in relation to the orientation description, for example, the orientation or position relationship indicated by the upper, lower, front, rear, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0029] In the description of the present application, the meaning of several is one or more, and the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, and above, below, etc. are understood as including the number. If it is described as first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0030] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0031] As Figure 1 and Figure 2As shown, the water swelling forming device according to the first aspect embodiment of the utility model, it includes upper die and lower die 100, upper die and lower die 100 are equipped with half cavity, the die can form water swelling forming cavity 110, first empty position 120 and second empty position 130, water swelling forming cavity 110 both sides are equipped with an opening, two openings are communicated with first empty position 120 and second empty position 130 respectively. In order to realize the guidance to upper die, upper die is connected with at least two guide columns, lower die 100 is equipped with the guide hole 140 corresponding with guide column;In order to realize the positioning to upper die, upper die is connected with several positioning columns, lower die 100 is equipped with the positioning hole 150 corresponding with positioning column.

[0032] The above structure is all the conventional setting of the existing water swelling forming device, wherein the first empty position 120 and the second empty position 130 are through to the outer surface of the mold, and the two are respectively used for the punch needle to extend into the water swelling forming cavity 110, and the water swelling forming cavity 110 is divided into a straight pipe forming cavity and a bent pipe forming cavity according to different products. When the water swelling forming cavity 110 is a straight pipe forming cavity, the two side openings of the water swelling forming cavity 110 have coaxial center axes; when the water swelling forming cavity 110 is a bent pipe forming cavity, the two side openings of the water swelling forming cavity 110 respectively have intersecting center axes. If further subdivided, if the center axes of the two side openings form an angle of ∠90°, then the water swelling forming cavity 110 is used for producing a 90° elbow joint, and if the center axes of the two side openings form an angle of ∠45°, then the water swelling forming cavity 110 is used for producing a 45° elbow joint. For ease of understanding, the following is described on the basis that the water swelling forming cavity 110 is a bent pipe forming cavity.

[0033] In order to be able to adapt to the elbow blank 200 with the screw head 210, the first empty position 120 is provided with a containing space 121 capable of accommodating the screw head 210 at a position close to the water swelling forming cavity 110. Since the outer size of the screw head 210 is greater than the outer diameter of the elbow joint, the cross-sectional size of the containing space 121 is also greater than the cross-sectional size of the water swelling forming cavity 110. When water swelling forming is needed, only the elbow blank 200 with the screw head 210 needs to be placed in the half cavity of the lower die 100, at this time the screw head 210 of the elbow blank 200 is located at the corresponding position of the containing space 121 and is positioned through the containing space 121, so as to define the position of the elbow blank 200 on the mold. After that, the upper die moves in the direction of the lower die 100 under the drive of the hydraulic cylinder, and finally the die of the upper die and the lower die 100 is completed. After the die is closed, the parting surface of the water swelling forming cavity 110 is sealed, and the water swelling forming cavity 110 is only communicated with the outside through the first empty position 120 and the second empty position 130.

[0034] On the other hand, the water bulging forming device further comprises a first punch needle 300 and a second punch needle 400, the first punch needle 300 and the second punch needle 400 are respectively connected to two power devices 500, the position of the first punch needle 300 is opposite to the position of the first avoiding space 120, the position of the second punch needle 400 is opposite to the position of the second avoiding space 130, and the two power devices 500 control the first punch needle 300 and the second punch needle 400 to respectively extend into the first avoiding space 120 and the second avoiding space 130. The first punch needle 300 or the second punch needle 400 is provided with an injection channel 330, and the injection channel 330 is communicated with an injection chamber 510 controlled by a hydraulic machine. During processing, the hydraulic machine injects liquid (usually water) into the elbow pipe blank 200 through the injection channel 330 by compressing the liquid, and the hydraulic machine continuously pressurizes, so that the water pressure in the elbow pipe blank 200 rises to 100MPa to 400MPa, and the elbow pipe blank 200 deforms under super-high water pressure and fits the water bulging forming cavity 110, thereby forming a specific shape. The key point of this technology is that the first punch needle 300 and the second punch needle 400 must seal the inner cavity of the elbow pipe blank 200 to avoid liquid leakage from the elbow pipe blank 200, and pressure relief is needed after processing to avoid high-pressure liquid being sprayed outwards at a very high speed, thereby causing damage to personnel or equipment.

[0035] Since the first avoiding space 120 is provided with a containing space 121 capable of accommodating the screw head 210 near the water bulging forming cavity 110, the technology can directly process the elbow pipe blank 200 with the screw head 210, at this time one end of the elbow pipe blank 200 is welded with the screw head 210, and the other end of the elbow pipe blank 200 remains the existing structure. In order to avoid the internal thread of the screw head 210 being deformed by the impact of high-pressure liquid during water bulging forming, thereby affecting the threaded connection after processing, it is necessary to improve the structure of the first punch needle 300.

[0036] As shown in Figure 3 , in addition to being provided with a first proximal shaft shoulder 321 at the end thereof, the first punch needle 300 is provided with a distal shaft shoulder 311 at a position away from the end, and the size of the distal shaft shoulder 311 is greater than that of the first proximal shaft shoulder 321, and the distance between the distal shaft shoulder 311 and the first proximal shaft shoulder 321 should be reasonably set. In contrast, the second punch needle 400 is only provided with a second proximal shaft shoulder 421 at the end.

[0037] The structure of the second punch pin 400 is a conventional design. During the hydroforming process, the front section of the second proximal shaft shoulder 421 can extend into the inside of the elbow blank 200. At this time, the second proximal shaft shoulder 421 is in sealing abutment with the pipe opening of the elbow blank 200, and a sealing structure is formed between the two. The high-pressure liquid in the elbow blank 200 cannot leak to the outside through the pipe opening of the elbow blank 200. The structure of the first punch pin 300 is a special design. During the hydroforming process, the first punch pin 300 gradually extends into the first avoidance position 120 until the first proximal shaft shoulder 321 of the first punch pin 300 is in sealing abutment with the narrowed position 220 between the elbow blank 200 and the screw head 210. The narrowed position 220 is formed based on the condition that the outer size of the screw head 210 is larger than the outer diameter of the elbow joint, and it exists as an inherent structure. At this time, the distal shaft shoulder 311 of the first punch pin 300 also abuts the outer side end face of the screw head 210.

[0038] Since the narrowed position 220 between the elbow blank 200 and the screw head 210 is sealed by the first proximal shaft shoulder 321 of the first punch pin 300, and the other end of the pipe blank is sealed by the second proximal shaft shoulder 421 of the second punch pin 400, the inside of the elbow blank 200 can be kept sealed during the hydroforming process. Since the position of the first proximal shaft shoulder 321 is beyond the internal thread of the screw head 210, the high-pressure liquid cannot enter the threaded section of the screw head 210 from the injection channel 330, so as to prevent the internal thread of the screw head 210 from being deformed by the impact of the ultra-high water pressure. The distal shaft shoulder 311 can limit the position of the screw head 210, so as to prevent the connection between the screw head 210 and the elbow blank 200 from being broken under the impact of the ultra-high water pressure.

[0039] In view of the tolerances of the screw head 210 and the size differences of different screw heads 210, it is quite difficult to achieve that when the first proximal shaft shoulder 321 of the first punch pin 300 is in sealing abutment with the narrowed position 220 between the elbow blank 200 and the screw head 210, the distal shaft shoulder 311 of the first punch pin 300 also abuts the outer side end face of the screw head 210. In most cases, it is only possible to ensure that the first proximal shaft shoulder 321 of the first punch pin 300 is in sealing abutment with the narrowed position 220 between the elbow blank 200 and the screw head 210, but it is not possible to simultaneously satisfy that the distal shaft shoulder 311 of the first punch pin 300 abuts the outer side end face of the screw head 210. Therefore, further improvement is needed for the structure of the first punch pin 300.

[0040] Specifically, the first punch needle 300 comprises a fixed part 310 and a movable part 320, the fixed part 310 is fixedly connected with the power device 500, and the fixed part 310 is provided with a groove 312 at an end away from the power device 500, and the groove 312 can accommodate the movable part 320. The outer circumferential surface of the movable part 320 is provided with a plurality of sliding grooves 323 arranged in the axial direction, and the fixed part 310 is provided with sliding blocks 313 slidingly connected with the sliding grooves 323, so that the movable part 320 can be axially movably nested in the fixed part 310, at this time, the first proximal shaft shoulder 321 is arranged at the end of the movable part 320, and the distal shaft shoulder 311 is arranged at the end of the fixed part 310. Since the sliding groove 323 has two limit positions, when any one of the limit positions of the sliding groove 323 abuts against the sliding block 313, at this time, the movable part 320 cannot continue to move in the predetermined direction, thereby limiting the movement path of the movable part 320 relative to the fixed part 310, so that the movable part 320 cannot be separated from the fixed part 310.

[0041] If the first punch needle 300 is provided with an injection channel 330, the movable part 320 and the fixed part 310 are both provided with the injection channel 330, but since the movable part 320 and the fixed part 310 have a separable state, when the movable part 320 is away from the fixed part 310, there is a gap 331 between the injection channel 330 of the movable part 320 and the injection channel 330 of the fixed part 310, and in the process of hydroforming, the high-pressure liquid will also fill the entire gap 331. In order to avoid the leakage of the high-pressure liquid from the connection between the movable part 320 and the fixed part 310 to the outside through the gap 331, firstly, it is necessary to ensure that the outer size of the movable part 320 and the inner size of the groove 312 are matched with high precision, and secondly, a sealing element 322 can be arranged between the end of the sliding groove 323 close to the fixed part 310 and the sliding block 313, and the sealing element 322 can be selected as a rubber gasket, when the high-pressure liquid acts on the sealing element 322, the sealing element 322 is deformed under stress to provide a sealing effect.

[0042] When working, the first punch needle 300 gradually extends into the screw head 210 of the elbow pipe blank 200 under the driving of the power device 500, until the first proximal shaft shoulder 321 of the movable part 320 seals against the narrow position 220 between the elbow pipe blank 200 and the screw head 210, since the distal shaft shoulder 311 of the fixed part 310 does not abut against the outer end face of the screw head 210 at this time, and the relative position of the movable part 320 and the fixed part 310 is adjustable, the power device 500 can continue to drive the fixed part 310 to move in the direction of the screw head 210 until the distal shaft shoulder 311 of the fixed part 310 abuts against the outer end face of the screw head 210. Not limited to the tolerance of the screw head 210 and the size difference of different screw heads 210, as long as the first proximal shaft shoulder 321 of the movable part 320 can seal against the narrow position 220 between the elbow pipe blank 200 and the screw head 210, the distal shaft shoulder 311 of the fixed part 310 can also abut against the outer end face of the screw head 210.

[0043] In the process of hydroforming, the high-pressure liquid also fills the gap 331 between the movable part 320 and the fixed part 310, at this time the high-pressure liquid exerts a force on the movable part 320, causing the first proximal shaft shoulder 321 of the movable part 320 to be able to seal against the narrow position 220 between the elbow pipe blank 200 and the screw head 210, thereby converting the thrust of the high-pressure liquid into part of the compression force of the power device 500, to effectively reduce the configuration requirements of the power device 500. Through the above-mentioned hydroforming device, the elbow joint with the screw head 210 can be directly processed to meet the needs of engineering projects.

[0044] As shown in Figure 1 and Figure 2 In some embodiments of the utility model, the number of hydroforming cavities 110 is multiple, and the number of hydroforming cavities 110 determines the number of products that can be formed in a machining process. When the number of hydroforming cavities 110 is two, two elbow joints can be produced in a machining process, which is commonly known as one out of two in the industry. When the number of hydroforming cavities 110 is four, four elbow joints can be produced in a machining process, which is commonly known as one out of four in the industry.

[0045] The elbow joint machining method according to the second aspect of the utility model comprises the following steps:

[0046] S100. Adopting slitting equipment to slit the stainless steel pipe into multiple straight pipes with a fixed length.

[0047] S200. The welding equipment is used for arranging and positioning the plurality of straight pipes, and a threaded end 210 is welded at one end of each straight pipe to obtain a plurality of straight pipe blanks. Since the straight pipes have consistent directionality at various angles, the plurality of straight pipes can be automatically positioned and arranged by a vibrating disc. During welding, a manipulator grabs the threaded end 210 and moves to the end of the straight pipe, and a welding robot performs welding along the weld to realize automatic welding.

[0048] S300. The pipe bending equipment is used for arranging and positioning the plurality of straight pipe blanks, and each straight pipe blank is bent to obtain a plurality of bent pipe blanks 200. Since the straight pipe blanks have consistent directionality at various angles, the plurality of straight pipe blanks can be automatically positioned and arranged by a vibrating disc. During bending, the straight pipe blanks pass through a plurality of bending rollers, and the pipe bending equipment can bend the straight pipe blanks into the bent pipe blanks 200 due to the angle difference between the bending rollers, and the process does not need manual intervention.

[0049] S400. The hydroforming device is used for hydroforming the bent pipe blank 200 to obtain a bent pipe joint with the threaded end 210. Before the present technology, since the industry lacks a corresponding hydroforming device, the welding process of the threaded end 210 is performed after the hydroforming process. However, the bent pipe has directionality, and it is very difficult to automatically position and arrange the bent pipe by a vibrating disc, so manual assistance is needed for welding, the welding efficiency is low, and since the hydroforming device generally outputs two or four, the manual assistance method cannot meet the requirements of mass production. Since the present technology develops a hydroforming device suitable for the bent pipe blank 200, the welding process of the threaded end 210 can be performed before the bending process and the hydroforming process. The existing welding equipment can automatically position and weld a plurality of straight pipes, and the existing pipe bending equipment can automatically position and bend a plurality of straight pipe blanks, which greatly improves the production efficiency, reduces the labor intensity of workers, reduces the production cost, and provides a technical basis for automatic production.

[0050] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art in the technical field, various changes can be made without departing from the spirit of the present application.

Claims

1. A water-expansion molding device, characterized in that, include: upper mold; The lower mold (100) is molded with the upper mold to form a water-expanding molding cavity (110), a first clearance position (120) and a second clearance position (130). The first clearance position (120) and the second clearance position (130) are respectively connected to the openings on both sides of the water-expanding molding cavity (110). The first clearance position (120) is provided with a receiving space (121) for accommodating the screw head (210) near the water-expanding molding cavity (110). A first punch (300) extends into the receiving space (121) through the first clearance (120). The end of the first punch (300) is provided with a first proximal shoulder (321), and the first punch (300) is provided with a distal shoulder (311) at a position away from the end. The size of the distal shoulder (311) is larger than the size of the first proximal shoulder (321). The second punch (400) extends into the water-swelling molding cavity (110) through the second clearance (130), and the end of the second punch (400) is provided with a second proximal shoulder (421); the first punch (300) or the second punch (400) is provided with an injection channel (330).

2. The hydroforming device according to claim 1, characterized in that: The first punch (300) is provided with an injection channel (330).

3. The water-expansion molding device according to claim 2, characterized in that: The first punch (300) includes a fixed part (310) and a movable part (320), the movable part (320) being movably nested in the fixed part (310), both the movable part (320) and the fixed part (310) being provided with the injection channel (330), the first proximal shoulder (321) being provided in the movable part (320), and the distal shoulder (311) being provided in the fixed part (310).

4. The water-expanding molding device according to claim 3, characterized in that: The outer peripheral surface of the movable part (320) is provided with a plurality of axially arranged sliding grooves (323), and the fixed part (310) is provided with a slider (313) slidably connected to the sliding grooves (323).

5. The hydroforming apparatus according to claim 4, characterized in that: The groove (323) has a sealing element (322) between its end near the fixing part (310) and the slider (313).

6. The hydroforming apparatus according to claim 1, characterized in that: The upper mold is connected to at least two guide pillars, and the lower mold (100) is provided with guide holes (140) corresponding to the guide pillars.

7. The water-expansion molding apparatus according to claim 1, characterized in that: The upper mold is connected to a plurality of positioning pins, and the lower mold (100) is provided with positioning holes (150) corresponding to the positioning pins.

8. The hydroforming apparatus according to claim 1, characterized in that: The number of the water-expanding molding cavities (110) is multiple.

9. The hydroforming apparatus according to claim 1 or 8, characterized in that: The two openings of the water-expanded molding cavity (110) have intersecting central axes.

10. The hydroforming apparatus according to claim 1 or 8, characterized in that: The openings on both sides of the water-expanding cavity (110) have a coaxial central axis.

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