CN115318927A - Variable-cross-section pipe fitting low-pressure hydraulic forming device and forming method thereof - Google Patents
Variable-cross-section pipe fitting low-pressure hydraulic forming device and forming method thereof Download PDFInfo
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- CN115318927A CN115318927A CN202210989809.6A CN202210989809A CN115318927A CN 115318927 A CN115318927 A CN 115318927A CN 202210989809 A CN202210989809 A CN 202210989809A CN 115318927 A CN115318927 A CN 115318927A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
- B21D26/033—Deforming tubular bodies
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
- B21D26/033—Deforming tubular bodies
- B21D26/045—Closing or sealing means
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a variable-cross-section pipe low-pressure hydraulic forming device and a forming method thereof.A die assembly driving mechanism drives a movable die assembly and a lower sealing seat to be matched, the movable die assembly comprises a pressing part and an upper sealing seat, the upper sealing seat is connected to one side of the pressing part, which is far away from the lower sealing seat, along the die assembly direction, the bottom end of a pipe fitting is hermetically connected onto the lower sealing seat, the top end of the pipe fitting penetrates through the pressing part and is hermetically connected onto the upper sealing seat, the die assembly driving mechanism is arranged in the same direction of the die assembly direction of the movable die assembly and the lower sealing seat and the sealing of the two ends of the pipe fitting, namely, the sealing of the two ends of the pipe fitting is realized by die assembly force exerted by the die assembly driving mechanism, the sealing assembly is in a conical structure, the sealing effect of the sealing assembly on the two ends of the pipe fitting is stronger when the upper sealing seat and the lower sealing seat are tightly supported, so that the sealing of the two ends of the pipe fitting is completed by the die assembly force in real time, and the pipe fitting does not need to do corresponding movement along with the movement of a die in the prior art, and further does not need to arrange a sealing oil cylinder and a device for driving the sealing seat to move.
Description
Technical Field
The invention relates to the technical field of pipe fitting forming and manufacturing, in particular to a variable-cross-section pipe fitting low-pressure hydraulic forming device and a forming method thereof.
Background
The automobile industry is the backbone industry of the national economy of China, and is the middle strength for realizing the double-carbon target in China. The light weight of the automobile is an important way for realizing the fuel saving and carbon emission reduction of the automobile. One main approach for reducing the weight of the automobile is to structurally replace a solid structure with a hollow structure, namely, a solid structure is replaced by the hollow structure, so that the strength and the rigidity of the material are fully utilized, the weight is reduced, the material is saved, and the light weight is realized. The internal high-pressure forming technology is an advanced hydraulic forming technology which can be developed under the trend and can manufacture the hollow structural pipe fitting in batches. The internal high-pressure forming technique is to apply fluid pressure to the inside of a pipe blank to make the pipe blank adhere to a mold cavity under the action of the internal fluid pressure, thereby manufacturing tubular parts with different cross-sectional shapes in the axial direction. In recent years, high-strength steel has been increasingly used for automobile structures in order to further reduce the weight of the automobile structures. Because the internal high-pressure forming pressure is inversely proportional to the fillet radius of the component and is proportional to the yield strength of the material, the improvement of the yield strength of the original tube blank inevitably leads to relatively high internal pressure required by adopting a pure bulging forming component, and the equipment mold clamping force required by the process is related to the product of the component forming pressure and the projection area, so the equipment tonnage required by internal high-pressure forming is often large, the mold size is large, and the investment is large.
The low-pressure hydraulic forming technology is a hydraulic forming technology which is developed in recent years and can greatly reduce the forming pressure of a variable-section pipe fitting. The concrete working principle is that after the interior of the pipe fitting is filled with a liquid medium and pressurized to a certain supporting pressure, the die is closed to press the pipe fitting, and the pipe fitting deforms under the combined action of the mechanical pressure of the die and the supporting pressure of the liquid inside the pipe fitting to form a required shape component. The low pressure hydraulic forming has no bulging process, so the pipe section has small or no change, and is especially suitable for the shape characteristics of most high-strength steel structural members. In the conventional low-pressure hydraulic forming, because the interior of the pipe needs to be filled with a liquid medium and pressurized to a certain supporting pressure before the pipe is pressed by the die, the two ends of the pipe must be sealed at the moment. When the pipe fitting is formed, the pipe fitting sealing is correspondingly moved along with the movement of a mould, for example, in a liquid filling and pressing forming device of a variable-section special-shaped pipe fitting disclosed in patent document CN111195673B, the pipe fitting is centrally placed into an integral female mould, and an upper mould base and a male mould arranged on the upper mould base move downwards to be attached to the pipe fitting; the left sealing oil cylinder and the right sealing oil cylinder drive the left sealing punch and the right sealing punch to advance to the pipe filling position, and the follow-up performance of pipe end sealing is guaranteed to lead to the fact that the die structure is complex. In addition, the simple unidirectional pressing inevitably brings about pipe friction, which affects the surface quality of the component. And the conventional low-pressure hydraulic forming process still needs to seal an oil cylinder and a pressurization system, so that the cost still has no great advantage, and the further application of low-pressure hydraulic forming is limited.
Disclosure of Invention
The invention aims to provide a variable-cross-section pipe fitting low-pressure hydraulic forming device and a forming method thereof, which are used for solving the problems in the prior art, so that the sealing and die assembly directions of a pipe fitting are the same, the internal pressure of a pipe fitting support is automatically established, a sealing oil cylinder and a pressurization system are not needed, the structure of the whole device is fully simplified, and the manufacturing cost and the pipe fitting forming manufacturing cost are reduced.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a low-pressure hydraulic forming device of a variable-cross-section pipe fitting, which comprises a movable die assembly, a lower sealing seat and a die assembly driving mechanism for driving the movable die assembly and the lower sealing seat to be matched, wherein an annular sealing groove used for being tightly inserted into the bottom end of the pipe fitting is formed in the lower sealing seat, a fluid channel communicated with the interior of the pipe fitting is formed in the inner peripheral side of the annular sealing groove, the fluid channel is communicated with a supply mechanism and a pressure stabilizing mechanism for providing a low-pressure hydraulic medium, the movable die assembly comprises an upper sealing seat and a pressing part used for pressing the pipe fitting to be formed, the upper sealing seat is connected to one side, away from the lower sealing seat, of the pressing part in the die assembly direction, the top end of the pipe fitting penetrates through the pressing part and is connected with the upper sealing seat, a sealing groove used for being tightly inserted into the top end of the pipe fitting is formed in the upper sealing seat, sealing assemblies are arranged between the outer peripheral side wall of the annular sealing groove and the inner peripheral side wall of the pipe fitting, and the sealing assembly, and the sealing assemblies are in a tapered structure gradually increased in the direction away from the pipe fitting.
Preferably, the sealing assembly comprises sealing rings respectively arranged at the bottom end of the annular sealing groove and the top end of the sealing groove, and positioning retaining rings used for pressing the sealing rings are further arranged in the annular sealing groove and the sealing groove.
Preferably, the sealing ring is a Y-shaped sealing ring, and a sealing lip of the Y-shaped sealing ring faces away from the end of the pipe fitting along the axial direction of the pipe fitting.
Preferably, the pressing part includes holding ring and holding ring down, is located go up the holding ring with just be the centre form of split structure between the holding ring down, the centre form includes a plurality of edges the split of pipe fitting circumference interval equipartition, adjacent two be connected with supporting spring between the split, go up the holding ring and/or the holding ring down with be equipped with the confession between the centre form the split is followed pipe fitting radial sliding's first guide way and first guiding key, the periphery side cover of centre form is equipped with the drive respectively the split is followed the external mold that pipe fitting axle center department removed.
Preferably, the outer side face of split is the slope column structure that follows from top to bottom pipe fitting periphery side slope, the external mold is the cover and is established the tubular structure of centre form periphery side, the external mold include with slope section, the drive of the lateral surface structure looks adaptation of split the gliding spacing section of split, spacing section is straight tube-shape and is located slope section top, and the butt is in on the lateral surface of split.
Preferably, the lower positioning ring is connected with a guide sleeve sleeved on the outer peripheral side of the pipe fitting, the bottom end of the outer die is connected with an annular positioning baffle plate coaxially arranged with the guide sleeve, and the annular positioning baffle plate is slidably sleeved on the peripheral wall of the guide sleeve and drives the outer die to move.
Preferably, the upper positioning ring is provided with a plurality of support rods for connecting the upper sealing seat, and each support rod surrounds the outer periphery of the pipe fitting.
Preferably, the top end of the upper sealing seat is abutted with a nitrogen spring for offsetting liquid counter force borne by the upper sealing seat, and one side of the nitrogen spring, which is far away from the upper sealing seat, is provided with a force application structure for supporting the nitrogen spring.
Preferably, the force application structure is a cylindrical structure, is sleeved on the periphery sides of the nitrogen spring and the upper sealing seat, and is connected with the outer die.
The forming method of the variable-cross-section pipe fitting low-pressure hydraulic forming device comprises the following steps:
placing an initial tube blank: according to design requirements, fixing a lower sealing seat on a die assembly driving mechanism, assembling an upper sealing seat, a die, the lower sealing seat and a guide sleeve, and then placing the assembled upper sealing seat, die, lower sealing seat and guide sleeve inside a force application structure and an outer die which are connected to form a movable die assembly positioned above the lower sealing seat, placing the movable die assembly on the die assembly driving mechanism integrally, and driving the die assembly to move upwards to a set height by the die assembly driving mechanism;
connecting the initial pipe fitting and the lower sealing seat: placing the pipe fitting into the space and inserting the bottom end of the pipe fitting into the lower seal seat;
die assembly: inserting the pipe fitting into a guide sleeve and a die, and carrying out die assembly on the movable die assembly and the lower sealing seat by a die assembly driving mechanism to drive the upper sealing seat to be in contact with the pipe blank so that the pipe fitting is positioned below a sealing ring of the upper sealing seat;
medium filling and exhausting: connecting the lower sealing seat with the supply mechanism and the pressure stabilizing mechanism, filling the medium into the pipe fitting through the supply mechanism, discharging the gas in the pipe fitting through a gap between the sealing ring and the upper sealing seat, and simultaneously finishing the exhaust work;
pressure stabilization: the die assembly driving mechanism continues to perform die assembly on the movable die assembly and the lower sealing seat, the upper sealing seat finishes sealing the top end of the pipe fitting, a medium in the pipe fitting is compressed, a supporting pressure is built in the inner cavity of the pipe fitting by itself, and the medium pressure is stabilized by the pressure stabilizing mechanism after the supporting pressure reaches a set value;
loading and pressing: the die assembly driving structure drives the movable die part to continuously move downwards, each split synchronously acts along the radial direction of the pipe fitting to load and press the pipe fitting, the pipe fitting is molded into a variable-section pipe fitting by attaching a die under the combined action of split mechanical pressure and medium pressure of an inner cavity, the volume of the pipe fitting is reduced, the medium in the pipe fitting is compressed, the supporting pressure is increased to a preset working pressure, and a pressure stabilizing system maintains the pressure of the medium after the working pressure is reached;
and (3) finishing the forming work: and (3) removing the internal pressure of the pipe fitting, driving the movable die assembly to move upwards by the die assembly driving mechanism, opening the movable die assembly and the lower sealing seat, taking out the formed pipe fitting, and cutting the variable-section pipe fitting to obtain the variable-section pipe fitting meeting the design requirement.
Compared with the prior art, the invention has the following technical effects:
first, because the die assembly actuating mechanism drives the movable die assembly and the lower seal receptacle to close the die, and the movable die assembly comprises a pressing part and an upper seal receptacle, the upper seal receptacle is connected to one side of the pressing part away from the lower seal receptacle along the die assembly direction, the bottom end of the pipe fitting is connected to the lower seal receptacle in a sealing manner, the top end of the pipe fitting penetrates through the pressing part and is connected to the upper seal receptacle in a sealing manner, the die assembly actuating mechanism sets the die assembly direction of the movable die assembly and the lower seal receptacle in the same direction as the seals at the two ends of the pipe fitting, namely, the seals at the two ends of the pipe fitting are realized by the die assembly force exerted by the die assembly actuating mechanism, and because the seal assembly is in a tapered structure, the pipe fitting is more closely contacted with the upper seal receptacle and the lower seal receptacle under the action of the die assembly, the seal effect of the seal assembly on the two ends of the pipe fitting is stronger, so that the upper seal receptacle and the lower seal receptacle can complete the sealing at the two ends of the pipe fitting by the die assembly through the die assembly force, the feed mechanism providing low-pressure hydraulic medium is communicated with the pressure stabilizing mechanism, the pipe fitting, and the sealing structure can be realized, and the automatic pipe fitting support device can be manufactured.
The second, seal assembly is including setting up the sealing washer on annular seal groove bottom and sealed fluting top respectively, and still is equipped with the location that is used for suppressing each sealing washer in annular seal groove and the sealed fluting and keeps off the ring, seals in order to accomplish the circumference to the pipe fitting tip through setting up the sealing washer to suppress the sealing washer through the location fender ring, in order to fix a position the sealing washer, avoid its dislocation to lead to the pipe fitting tip can not alternate in the sealing washer, cause sealed effect to become invalid.
And thirdly, the sealing ring is a Y-shaped sealing ring, a sealing lip of the Y-shaped sealing ring faces back to the end part of the pipe fitting along the axial direction of the pipe fitting, and the Y-shaped sealing ring radially expands along the pipe fitting under the pressing action of the positioning baffle ring so as to improve the sealing effect on the pipe fitting.
Fourthly, the pressing part comprises an upper positioning ring and a lower positioning ring, an inner die which is positioned between the upper positioning ring and the lower positioning ring and has a split structure, the inner die comprises a plurality of split parts which are uniformly distributed along the circumferential direction of the pipe fitting at intervals, a supporting spring is connected between every two adjacent split parts, a first guide groove and a first guide key which are used for enabling the split parts to slide along the radial direction of the pipe fitting are arranged between the upper positioning ring and/or the lower positioning ring and the inner die, an outer die which drives each split part to move along the axis of the pipe fitting is sleeved on the outer peripheral side of the inner die, each split part is connected through the supporting spring, force is applied to each split part along the circumferential direction, the synchronism and the uniformity of each split part moving are guaranteed, each split part is guaranteed to move directionally by arranging the first guide groove and the first guide key, and the effectiveness of pressing the pipe fitting is guaranteed.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic structural view of a variable cross-section pipe fitting according to the present invention
FIG. 2 is a three-dimensional overall outline view of the variable cross-section pipe fitting low-pressure hydroforming device of the present invention
FIG. 3 is a schematic structural diagram of a low-pressure hydroforming device for a variable cross-section pipe fitting according to the present invention
FIG. 4 is a sectional view of the inner mold of the forming device of the present invention
FIG. 5 is a view of a part of the split inner mold 1 of the forming device of the present invention
FIG. 6 is a drawing of a positioning ring of the forming device of the present invention
FIG. 7 is a view of the lower positioning ring of the forming device of the present invention
FIG. 8 is a view showing the structure of the inner mold of the forming device of the present invention
FIG. 9 is a view showing the structure of the connection between the inner mold and the upper sealing punch of the forming device of the present invention
FIG. 10 is a drawing of an outer mold part of the molding apparatus of the present invention
FIG. 11 is a schematic flow diagram of an in-mold formed part of the present invention
FIG. 12 is a schematic view of a forming method of the present invention
Wherein, 1, pipe fittings; 2. a force application structure; 3. a nitrogen spring; 4. a lower seal seat; 5. a seal ring; 6. positioning a baffle ring; 7. an upper seal seat; 8. a support bar; 9. an upper positioning ring; 10. a pull rod; 11. a lower positioning ring; 12. a support spring; 13. splitting; 14. an outer mold; 15. an annular positioning baffle; 16. a one-way valve; 17. a variable frequency water pump; 18. a pressure stabilizing overflow valve; 19. an unloading electromagnetic valve; 20. and (4) a box body.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a variable-cross-section pipe fitting low-pressure hydraulic forming device and a forming method thereof, which are used for solving the problems in the prior art, so that the sealing and die assembly directions of a pipe fitting are the same, the internal pressure of a pipe fitting support is automatically established, a sealing oil cylinder and a pressurization system are not needed, the structure of the whole device is fully simplified, and the manufacturing cost and the pipe fitting forming manufacturing cost are reduced.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Referring to fig. 1 to 12, the present embodiment provides a low-pressure hydraulic forming apparatus for a variable cross-section pipe, wherein the pipe 1 is made of the following materials: SPFH440, wall thickness: 2.0mm, the whole device comprises a movable die assembly, a lower seal seat 4, a die assembly driving mechanism for driving the movable die assembly and the lower seal seat 4 to close the die, an annular seal groove used for tightly inserting the bottom end of the pipe fitting 1 is formed in the lower seal seat 4, a fluid channel communicated with the interior of the pipe fitting 1 is formed in the inner peripheral side of the annular seal groove, the fluid channel is communicated with a supply mechanism and a pressure stabilizing mechanism for providing low-pressure hydraulic medium, the movable die assembly comprises an upper seal seat 7 and a pressing part used for pressing the pipe fitting 1 to be formed, the upper seal seat 7 is connected to one side of the pressing part, far away from the lower seal seat 4, the top end of the pipe fitting 1 penetrates through the pressing part and is connected with the upper seal seat 7, a seal groove used for tightly inserting the top end of the pipe fitting 1 is formed in the upper seal seat 7, and seal assemblies are arranged between the outer peripheral side wall of the annular seal groove and the inner peripheral side wall of the seal groove and the outer peripheral side wall of the pipe fitting 1, the sealing assembly is a conical structure with a structure gradually enlarged along the direction far away from the pipe fitting 1, the die assembly driving mechanism drives the movable die assembly and the lower sealing seat 4 to perform die assembly, the movable die assembly comprises a pressing part and an upper sealing seat 7, the upper sealing seat 7 is connected to one side of the pressing part far away from the lower sealing seat 4 along the die assembly direction, the bottom end of the pipe fitting 1 is hermetically connected onto the lower sealing seat 4, the top end of the pipe fitting 1 penetrates through the pressing part to be hermetically connected onto the upper sealing seat 7, the die assembly driving mechanism is arranged in the same direction with the die assembly direction of the movable die assembly and the lower sealing seat 4 and the sealing direction of the two ends of the pipe fitting 1, namely, the sealing of the two ends of the pipe fitting 1 is realized by the die assembly force applied by the die assembly driving mechanism, and the sealing assembly is in the conical structure, the tighter the contact between the pipe fitting 1 and the upper sealing seat 7 and the lower sealing seat 4 under the die assembly force, the stronger the sealing action of the sealing assembly on the two ends of the pipe fitting 1, make upper seal seat 7 and lower seal seat 4 accomplish the sealed to pipe fitting 1 both ends through the clamping force in real time, need not prior art in the forming process again, pipe fitting 1 is sealed to be along with the motion of mould does corresponding motion, and then need not to set up sealed hydro-cylinder and the device that the drive seal seat removed, and be equipped with fluid passage under on seal seat 4, and the intercommunication has supply mechanism and the steady voltage mechanism that provides low pressure hydraulic medium, after pipe fitting 1 both ends are sealed, realized pipe fitting 1 and supported interior pressure automatic establishment, the whole device structure has fully been simplified, and the cost of preparation and pipe fitting 1 shaping preparation has been reduced.
Wherein, seal assembly is including setting up the sealing washer 5 on annular seal groove bottom and sealed fluting top respectively, and still be equipped with the location that is used for suppressing each sealing washer 5 in annular seal groove and the sealed fluting and keep off ring 6, through setting up sealing washer 5 in order to accomplish the circumference of 1 tip of pipe fitting sealed to keep off ring 6 through the location and suppress sealing washer 5, in order to fix a position sealing washer 5, avoid its dislocation to lead to 1 tip of pipe fitting can not alternate in sealing washer 5, cause sealed effect to become invalid.
Furthermore, the sealing ring 5 is a Y-shaped sealing ring 5, the sealing lip of the Y-shaped sealing ring 5 faces away from the end part of the pipe fitting 1 along the axial direction of the pipe fitting 1, and under the pressing action of the positioning baffle ring 6, the Y-shaped sealing ring 5 radially expands along the pipe fitting 1, so that the sealing effect on the pipe fitting 1 is improved, and the pipe end can be conveniently plugged and sealed.
Further, the pressing portion comprises an upper positioning ring 9 and a lower positioning ring 11, an inner die which is located between the upper positioning ring 9 and the lower positioning ring 11 and is of a split 13 structure, the inner die comprises a plurality of splits 13 which are uniformly distributed along the circumferential direction of the pipe fitting 1 at intervals, a supporting spring 12 is connected between every two adjacent splits 13, a first guide groove 21 and a first guide key which are used for enabling the splits 13 to slide along the radial direction of the pipe fitting 1 are arranged between the upper positioning ring 9 and/or the lower positioning ring 11 and the inner die, an outer die 14 which drives the splits 13 to move along the axis of the pipe fitting 1 is sleeved on the outer circumferential side of the inner die, the splits 13 are connected through the supporting spring 12, force is applied to the splits 13 along the circumferential direction, the synchronism and the uniformity of the movement of the splits 13 are ensured, the directional movement of the splits 13 is ensured by arranging the first guide groove 21 and the first guide key, and the effectiveness of pressing the pipe fitting 1 is ensured. And the inner mold of the split 13 is in an initial state of being completely opened to the maximum state due to the supporting spring 12. Preferably, a plurality of evenly arranged pull rods 10 are connected between the upper positioning ring 9 and the lower positioning ring 11.
Preferably, the outer side surface of the split 13 is an inclined structure inclined from top to bottom along the outer peripheral side of the pipe 1, the outer mold 14 is a cylindrical structure sleeved on the outer peripheral side of the inner mold, the outer mold 14 comprises an inclined section matched with the outer side surface structure of the split 13 and a limiting section for driving the split 13 to slide, the limiting section is in a straight cylinder shape and is positioned above the inclined section and abutted against the outer side surface of the split 13, the position relation between the upper seal seat 7 and the top end of the pipe 1 is controlled by the sliding of the inclined section and the split 13 in a matching manner, the upper seal seat is not completely contacted, a space for discharging gas inside the pipe 1 is formed, the split 13 is pressed by the limiting section, the split 13 is driven to move towards the inner side, and the upper seal seat 7 completes the sealing of the top end of the pipe 1. Preferably, a second guide groove and a second guide key for movably guiding the outer mold 14 are provided between the outer mold 14 and the corresponding split 13.
The lower positioning ring 11 is connected with a guide sleeve sleeved on the outer periphery of the pipe fitting 1, the bottom end of the outer die 14 is connected with an annular positioning baffle plate 15 which is coaxial with the guide sleeve, the annular positioning baffle plate 15 is sleeved on the outer peripheral wall of the guide sleeve in a sliding mode and drives the outer die 14 to move, the outer die 14 is guaranteed to move and position through the guide sleeve, driving work on the split piece 13 is effectively completed, preferably, an annular flange is arranged at the top of the guide sleeve along the circumferential direction and is clamped on the inner side of the bottom end of the outer die 14, and the outer die 14 is prevented from being reversely separated from the guide sleeve.
Further, go up holding ring 9 and be equipped with a plurality of bracing pieces 8 that are used for connecting upper seal seat 7, each bracing piece 8 encircles at the periphery side of pipe fitting 1, accomplishes being connected of pressing part and upper seal seat 7 through bracing piece 8, and then accomplishes the location and the sealed effect at pipe fitting 1 top, and the even distribution of each bracing piece 8 has guaranteed that the atress of going up holding ring 9 and upper seal seat 7 is even.
Furthermore, the top end of the upper sealing seat 7 is abutted with the nitrogen spring 3 for offsetting the liquid counter force applied to the upper sealing seat, one side of the nitrogen spring 3, which is far away from the upper sealing seat 7, is provided with the force application structure 2 for supporting the nitrogen spring, and the acting force offsets the liquid counter force applied to the upper sealing seat 7.
Preferably, the force application structure 2 is a cylindrical structure, the force application structure 2 is sleeved on the outer peripheral sides of the nitrogen spring 3 and the upper seal seat 7 and is connected with the outer die 14, that is, a structure following the outer die 14 is formed, so that in the process that the outer die 14 moves to press each split 13, the force application structure 2 presses the nitrogen spring 3, and it is ensured that the hydraulic pressure rebound received by the upper seal seat 7 is fully counteracted.
Preferably, the supply mechanism and the pressure stabilizing mechanism are provided with a one-way valve 16, a variable frequency water pump 17, a pressure stabilizing overflow valve 18, an unloading electromagnetic valve 19 and a box body 20. The input end of the variable frequency water pump 17 is connected with the box body 20 through a pipeline and is used for sucking media; the other end of the variable frequency water pump 17 is connected with the lower sealing seat 4 through a pipeline and a one-way valve 16. Wherein the pressure control range of the pressure stabilizing overflow valve 18 is 5-25MPa.
Further, a forming method of the low-pressure hydraulic forming device for the variable cross-section pipe fitting 1 is further provided, and comprises the following steps:
placing an initial tube blank: fixing a lower sealing seat 4 on a die assembly driving mechanism according to design requirements, assembling an upper sealing seat 7, a die, the lower sealing seat 4 and a guide sleeve, and then placing the assembled components on the inner sides of a force application structure 2 and an outer die 14 which are connected with each other to form a movable die component positioned above the lower sealing seat 4, integrally placing the movable die component on the die assembly driving mechanism, and driving the die component to move upwards to a set height by the die assembly driving mechanism;
connecting the initial tubular 1 and the lower seal seat 4: placing the pipe fitting 1 into the space, and inserting the bottom end of the pipe fitting 1 into the lower seal seat 4;
and (3) die assembly: inserting the pipe fitting 1 into a guide sleeve and a die, driving a die assembly and a lower sealing seat 4 to be matched by a die matching driving mechanism, and driving an upper sealing seat 7 to be in contact with a pipe blank, so that the pipe fitting 1 is positioned below a sealing ring 5 of the upper sealing seat 7;
medium filling and exhausting: connecting the lower sealing seat 4 with a supply mechanism and a pressure stabilizing mechanism, filling the medium into the pipe fitting 1 through the supply mechanism, discharging the gas in the pipe fitting 1 through a gap between the sealing ring 5 and the upper sealing seat 7, and simultaneously finishing the exhaust work;
pressure stabilization: the die assembly driving mechanism continues to perform die assembly on the movable die assembly and the lower sealing seat 4, the upper sealing seat 7 finishes top end sealing of the pipe fitting 1, a medium in the pipe fitting 1 is compressed, supporting pressure is built in the cavity of the pipe fitting 1 automatically, and the medium pressure is stabilized by the pressure stabilizing mechanism after the supporting pressure reaches a set value; the supporting pressure is automatically built in the inner cavity of the tube blank, and simultaneously, the nitrogen spring 3 starts to work, and the acting force of the nitrogen spring counteracts the liquid counter force borne by the upper sealing seat 7;
loading and pressing: the die assembly driving structure drives the die part to continuously move downwards, each split 13 synchronously moves along the radial direction of the pipe fitting 1 to load and press the pipe fitting 1, the pipe fitting 1 is molded into the pipe fitting 1 with the variable cross section under the combined action of the mechanical pressure of the split 13 and the medium pressure of the inner cavity, the volume of the pipe fitting 1 is reduced, the medium in the pipe fitting 1 is compressed, the supporting pressure is increased to the preset working pressure, and the pressure stabilizing system maintains the pressure of the medium after the working pressure is reached;
and finishing the forming work: and (3) removing the internal pressure of the pipe fitting 1, driving the movable die assembly to move upwards by the die assembly driving mechanism, opening the movable die assembly and the lower sealing seat 4, taking out the molded pipe fitting 1, and cutting the variable-section pipe fitting 1 to obtain the variable-section pipe fitting 1 meeting the design requirement.
The comparison of this example with conventional internal high pressure forming is illustrated as follows:
first, the forming internal pressure of the present embodiment is 10MPa, and if the conventional internal high pressure forming is adopted, the shaping pressure is about 120MPa according to the formula Pc = t × σ s × rc. Secondly, the present embodiment adopts partial hydroforming with a forming length of 100mm, whereas the conventional internal high pressure forming adopts integral forming with a forming length of 600mm, which compares 6:1. in conclusion, in the embodiment, if the conventional internal high pressure forming is adopted, the tonnage of equipment is at least about 500 tons, while the tonnage of the equipment is about 70 tons by adopting the method and the device, a sealed oil cylinder and a pressurization system are not needed, and the cost is obviously reduced.
And the adaptation according to the actual needs is within the protection scope of the present invention.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the foregoing, the description is not to be taken in a limiting sense.
Claims (10)
1. The utility model provides a low pressure hydraulic forming device of variable cross section pipe fitting, its characterized in that, includes movable mould subassembly, lower seal receptacle, drive the compound die actuating mechanism of movable mould subassembly and lower seal receptacle compound die, offer on the seal receptacle down and be used for closely knit grafting the annular seal groove of pipe fitting bottom, the interior week side of annular seal groove open be equipped with the inside fluid passage who is linked together of pipe fitting, fluid passage intercommunication has supply mechanism and the steady voltage mechanism that provides low pressure hydraulic medium, the movable mould subassembly includes the upper seal receptacle, is used for the suppression the fashioned suppression portion of pipe fitting, the upper seal receptacle is connected along the compound die direction the suppression portion is kept away from one side of seal receptacle down, the pipe fitting top pass the suppression portion and with the upper seal receptacle is connected, the upper seal receptacle is offered and is used for closely knit grafting the sealed fluting on pipe fitting top, the outer peripheral side wall of annular seal groove with the inner peripheral side wall of sealed fluting all with be equipped with seal assembly between the outer peripheral side wall of pipe fitting, seal assembly is the structure along the direction of keeping away from the pipe fitting gradually big toper structure.
2. The low-pressure hydroforming apparatus according to claim 1, wherein the sealing assembly comprises sealing rings disposed at a bottom end of the annular sealing groove and at a top end of the sealing groove, and a retaining ring is disposed in the annular sealing groove and the sealing groove for pressing each sealing ring.
3. The variable cross-section pipe low pressure hydroforming apparatus according to claim 2, wherein the sealing ring is a Y-shaped sealing ring having a sealing lip facing away from the end of the pipe in the direction of the pipe axis.
4. The low-pressure hydraulic forming device for the variable-cross-section pipe fitting according to claim 2 or 3, wherein the pressing portion comprises an upper positioning ring and a lower positioning ring, and an inner mold which is located between the upper positioning ring and the lower positioning ring and has a split structure, the inner mold comprises a plurality of split segments which are uniformly distributed along the circumferential direction of the pipe fitting at intervals, a supporting spring is connected between every two adjacent split segments, a first guide groove and a first guide key for the split segments to slide along the radial direction of the pipe fitting are arranged between the upper positioning ring and/or the lower positioning ring and the inner mold, and an outer mold for driving the split segments to move along the axial center of the pipe fitting is sleeved on the outer circumferential side of the inner mold.
5. The low-pressure hydraulic forming device for the variable-section pipe fitting as claimed in claim 4, wherein the outer side surface of the split is a tilted structure tilted from top to bottom along the outer side surface of the pipe fitting, the outer mold is a cylindrical structure sleeved on the outer side surface of the inner mold, the outer mold comprises a tilted section matched with the structure of the outer side surface of the split and a limiting section driving the split to slide, and the limiting section is in a straight cylinder shape, is located above the tilted section, and abuts against the outer side surface of the split.
6. The low-pressure hydraulic forming device for the variable-cross-section pipe fitting as claimed in claim 5, wherein the lower positioning ring is connected with a guide sleeve sleeved on the outer periphery of the pipe fitting, the bottom end of the outer die is connected with an annular positioning baffle plate coaxially arranged with the guide sleeve, and the annular positioning baffle plate is slidably sleeved on the outer peripheral wall of the guide sleeve and drives the outer die to move.
7. The low pressure hydroforming apparatus according to claim 6, wherein the upper retainer ring has a plurality of support rods for connecting to the upper seal housing, each of the support rods surrounding an outer circumferential side of the tube.
8. The low-pressure hydraulic forming device for the variable cross-section pipe fitting as claimed in claim 7, wherein a nitrogen spring for counteracting liquid reaction force applied to the nitrogen spring is abutted to the top end of the upper sealing seat, and a force application structure for supporting the nitrogen spring is arranged on one side of the nitrogen spring away from the upper sealing seat.
9. The low-pressure hydraulic forming device for the variable-cross-section pipe fitting as claimed in claim 8, wherein the force application structure is a cylindrical structure, is sleeved on the outer peripheral sides of the nitrogen spring and the upper seal seat, and is connected with the outer die.
10. The forming method of the variable cross-section pipe fitting low-pressure hydraulic forming device according to claim 9 is characterized by comprising the following steps of:
placing an initial tube blank: fixing a lower sealing seat on a die assembly driving mechanism according to design requirements, assembling an upper sealing seat, a die, the lower sealing seat and a guide sleeve, and then placing the assembled upper sealing seat, the die, the lower sealing seat and the guide sleeve on the inner sides of a connected force application structure and an outer die to form a movable die assembly positioned above the lower sealing seat, integrally placing the movable die assembly on the die assembly driving mechanism, and driving the die assembly to move upwards to a set height by the die assembly driving mechanism;
connecting the initial pipe fitting and the lower sealing seat: placing the pipe fitting into the space and inserting the bottom end of the pipe fitting into the lower seal seat;
die assembly: inserting the pipe fitting into a guide sleeve and a die, and carrying out die assembly on the movable die assembly and the lower sealing seat by a die assembly driving mechanism to drive the upper sealing seat to be in contact with the pipe blank so that the pipe fitting is positioned below a sealing ring of the upper sealing seat;
medium filling and exhausting: connecting the lower sealing seat with the supply mechanism and the pressure stabilizing mechanism, filling the medium into the pipe fitting through the supply mechanism, discharging the gas in the pipe fitting through a gap between the sealing ring and the upper sealing seat, and simultaneously finishing the exhaust work;
pressure stabilization: the die assembly driving mechanism continues to perform die assembly on the movable die assembly and the lower sealing seat, the upper sealing seat finishes sealing the top end of the pipe fitting, a medium in the pipe fitting is compressed, a supporting pressure is built in the inner cavity of the pipe fitting by itself, and the medium pressure is stabilized by the pressure stabilizing mechanism after the supporting pressure reaches a set value;
loading and pressing: the die assembly driving structure drives the movable die part to continuously move downwards, each split synchronously acts along the radial direction of the pipe fitting to load and press the pipe fitting, the pipe fitting is molded into a variable-section pipe fitting by attaching a die under the combined action of split mechanical pressure and medium pressure of an inner cavity, the volume of the pipe fitting is reduced, the medium in the pipe fitting is compressed, the supporting pressure is increased to a preset working pressure, and a pressure stabilizing system maintains the pressure of the medium after the working pressure is reached;
and finishing the forming work: and (3) removing the internal pressure of the pipe fitting, driving the movable die assembly to move upwards by the die assembly driving mechanism, opening the movable die assembly and the lower sealing seat, taking out the molded pipe fitting, and cutting the variable-section pipe fitting to obtain the variable-section pipe fitting meeting the design requirement.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210989809.6A CN115318927B (en) | 2022-08-18 | 2022-08-18 | Low-pressure hydraulic forming device and forming method for variable-section pipe fitting |
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| CN202210989809.6A CN115318927B (en) | 2022-08-18 | 2022-08-18 | Low-pressure hydraulic forming device and forming method for variable-section pipe fitting |
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| CN115318927A true CN115318927A (en) | 2022-11-11 |
| CN115318927B CN115318927B (en) | 2023-06-02 |
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| CN114682668A (en) * | 2022-03-31 | 2022-07-01 | 大连理工大学 | Pipe hot fluid high-pressure forming sealing device and method in vacuum environment |
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| JP2005199322A (en) * | 2004-01-16 | 2005-07-28 | Kawasaki Heavy Ind Ltd | Bulge forming device and method, and molded product using the same |
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| CN115318927B (en) | 2023-06-02 |
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