CN111922173A - Multi-stage omega-shaped pipe fluctuation internal high-pressure forming process - Google Patents
Multi-stage omega-shaped pipe fluctuation internal high-pressure forming process Download PDFInfo
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- CN111922173A CN111922173A CN202011050053.6A CN202011050053A CN111922173A CN 111922173 A CN111922173 A CN 111922173A CN 202011050053 A CN202011050053 A CN 202011050053A CN 111922173 A CN111922173 A CN 111922173A
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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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Abstract
The invention discloses a multi-stage omega tube fluctuating internal high-pressure forming process, which comprises the following steps: a. early preparation: placing the pipe fitting into a corresponding forming die, wherein plugs are arranged at two ends of the forming die and close to two ends of the pipe fitting for sealing; b. and (3) rapid pressurization: pressurizing the inner wall of the pipe through the plug until the plastic deformation limit of the pipe fitting is reached; c. wave forming: in the pressure forming stage, the pipe fitting is continuously pressurized, so that the pipe fitting begins to expand; a pressure relief and material supplementing stage, wherein after pressurization is carried out for a certain time, the internal pressure of the pipe fitting is reduced to be below a plastic deformation limit; a fluctuating loading stage, namely a pressurizing forming stage-a pressure relief material supplementing stage through multiple cycles, and d, high-pressure shaping: and (3) rapidly pressurizing the pipe fitting to enable the pipe fitting to generate micro deformation to be attached to the forming die. The process of the invention enables the undeformed region to feed the deformed region in time through the fluctuating loading path, thereby improving the forming quality and forming capability of the deformed region.
Description
Technical Field
The invention relates to the technical field of internal high-pressure forming, in particular to a multi-stage omega-shaped pipe fluctuation internal high-pressure forming process.
Background
The internal high-pressure forming technology is an advanced plastic processing technology developed for forming a hollow variable-section tubular member characterized by light weight and integration, and is a perfect combination of structure light weight and flexible processing technology. Compared with a punching welding or insert welding process, the integrally formed pipe fitting has the advantages of high forming precision, small assembly error, improvement on the fluidity of a transport medium in the pipe and the like, and is widely applied to pipeline systems in the fields of water heating engineering, nuclear power engineering, mineral powder conveying, petrochemical natural gas and the like.
In the aspect of forming media, fluid media (water, emulsion, hydraulic oil and the like) are most mature, are widely used for forming reducer pipes and bending axial pipes, and can be matched with a pipe bending process to obtain large pipes with complex space axes and section shapes through high internal pressure. The forming process is generally divided into three stages of air exhaust sealing → supplementary forming → local shaping. The material supplementing mainly depends on the axial pushing of the pushing head to push the pipe fitting material to flow inwards, and at the moment, the pipe wall material mainly realizes the force transmission effect through axial compressive stress; meanwhile, the pipe wall material has larger radial compressive stress under the action of an internal fluid medium, so that the friction between the outer wall of the pipe and a forming die is increased, and the material flow is blocked, so that the main deformation area is often seriously thinned or even broken and failed due to untimely material supplement of peripheral materials; and when a plurality of sections on one pipe fitting need to form a multi-stage omega pipe, the poor material supplementing effect becomes obvious.
Therefore, aiming at the problems of serious wall thickness reduction of the pipe fitting, low forming limit and the like caused by poor material supplementing effect of the existing multi-stage omega-shaped pipe internal high-pressure forming process, the multi-stage omega-shaped pipe fluctuation internal high-pressure forming technology which has good material supplementing effect, effectively relieves the wall thickness reduction problem of the pipe fitting and effectively improves the forming limit of the pipe fitting needs to be provided urgently.
Disclosure of Invention
Aiming at the defects of the prior art, the multi-stage omega-shaped pipe fluctuation internal high-pressure forming process is provided, and in the material supplementing and forming stage, the material is supplemented to a deformation region from an undeformed region in time through a fluctuation loading path, so that the forming quality and the forming capacity of the deformation region are improved.
In order to achieve the above object, the present invention provides the following technical solutions.
The multi-stage omega tube fluctuating internal high-pressure forming process comprises the following steps:
a. early preparation: placing the pipe fitting into a corresponding forming die, and closing the forming die, wherein the pipe fitting is sequentially provided with a plurality of sections to be formed along the axial direction, the left end and the right end of the forming die are respectively provided with a plug and a driving element, and the driving element pushes the plugs to move into the pipe fitting axially, so that the two plugs are positioned at the two ends of one section to be formed, and the two ends of the section to be formed are sealed;
b. and (3) rapid pressurization: filling liquid and pressurizing the pipe fitting of the section to be formed through the plug until the plastic deformation limit of the pipe fitting is reached; wherein the loading path of the pressure on the pipe fitting is as follows:
wherein P is the pressure on the pipe,
is a constant, t is the loading time of the pipe fitting;
c. wave forming:
in the pressure forming stage, when the pressure is quickly increased to the plastic deformation limit of the pipe fitting, the pipe fitting is continuously pressurized, so that the pipe fitting begins to expand; in the pressure relief and material supplement stage, after the pipe fitting is pressurized and expanded, the pressure of the pipe fitting is relieved to reduce the internal pressure of the pipe fittingDown to below the plastic deformation limit, enabling the pipe to be fed; the loading path of the pressure of the pipe fitting is as follows:
wherein P is the pressure on the pipe,
is the pressure reached during the rapid pressurization period, t is the time to load the pipe;
the pressure forming stage and the pressure relief material supplementing stage are circulated for multiple times to realize fluctuating loading;
d. high-pressure shaping: after the wave loading period is finished, quickly pressurizing the pipe fitting to enable the pipe fitting to generate micro deformation to be attached to a forming die, so that the section forms a multi-stage omega pipe; the loading path of the pressure of the pipe fitting is as follows:
wherein P is the pressure on the pipe,
is a constant, t is the loading time of the pipe fitting;
e. and (3) repeated forming: c, relieving the pressure of the pipe fitting of the section to be formed, driving the two plugs to move in the same direction in the pipe fitting by the two driving elements until the two plugs move into two ends of the next section to be formed, sealing the two ends of the section to be formed, and repeating the step b, the step c and the step d in sequence; so that the section forms a multi-step omega tube; and repeating the steps to form all the areas to be formed until the final formed part meeting the requirement is formed.
The invention has the beneficial effects that: in the forming process, in the material supplementing and forming stage, the pipe fitting is continuously pressurized by wave forming when the pipe fitting is rapidly pressurized to the plastic deformation limit, so that the pipe fitting starts to expand, and the internal pressure of the pipe fitting is reduced to be below the plastic deformation limit after the pipe fitting is pressurized for a certain time; the pressure forming stage and the pressure relief material supplementing stage are circulated for multiple times to realize fluctuating loading; make the pipe fitting can expand the shape through the pressurization, again can be at effective feed supplement when the low pressure, after the undulant loading stage is accomplished, pressurize the pipe fitting fast, make the pipe fitting take place the micro deformation and lean on forming die, the final forming part that satisfies the demand takes place, through undulant loading route, make the zone of not deforming in time feed supplement to the zone of deforming, improve the forming quality and the shaping ability of zone of deforming, and through setting up end cap and drive element, make when the multistage omega pipe of a district takes shape the back, drive element drives the end cap and removes to the multistage omega pipe of the both ends of the next zone of waiting to take shape, for a plurality of districts take shape simultaneously, this application is through the method that the segmentation takes shape, take shape at every turn and only to a zone of shaping, make the feed supplement effectual.
As an improvement of the invention, in the pressure relief and material supplementing stage, the left and right plugs apply axial force to the two ends of the pipe fitting from the beginning of plastic deformation of the pipe fitting so as to supplement the blank required by expansion of the pipe fitting.
As an improvement of the invention, the plug comprises a sealing ring, an expansion ring, a circular plate, a first push rod and a second push rod, and the driving element comprises a first hydraulic cylinder and a second hydraulic cylinder;
one end of the second push rod is in transmission connection with the second hydraulic cylinder, the other end of the second push rod protrudes to form a second abutting part, an accommodating part is further formed on the second push rod, the first hydraulic cylinder is arranged in the accommodating part, one end of the first push rod is in transmission connection with the first hydraulic cylinder, the other end of the first push rod penetrates through the second abutting part and protrudes to form a first abutting part, the first abutting part and the second abutting part are coaxially arranged, and the sealing ring, the expansion ring and the circular plate are sequentially sleeved on the first push rod and are positioned between the first abutting part and the second abutting part;
in the step a, the two first hydraulic cylinders respectively push the first push rods to extend out, the sealing ring and the expansion ring are pushed into the pipe fitting in the forming die, the second hydraulic cylinder pushes the second push rod, the circular plate is pushed to abut against the sealing ring, the first hydraulic cylinder drives the first push rod to retract, the first push rod abuts against the expansion ring through the stop block, so that the expansion ring is expanded, the sealing ring is driven to expand when the expansion ring is expanded, and the sealing ring is attached to the inner wall of the pipe fitting, so that the pipe fitting is sealed;
in the step e, the two first driving elements at the two ends of the forming die respectively drive the first push rods to move in the same direction in the pipe fitting, and the two second driving elements respectively drive the second push rods to move in the same direction in the pipe fitting, so that the two plugs move to the two ends of the next section to be formed.
As an improvement of the invention, the periphery of the sealing ring is provided with a plurality of convex rings, the convex rings are arranged at intervals along the axial direction, a ring groove is formed between every two adjacent convex rings, and when the sealing ring is expanded, the convex rings are abutted against the inner wall of the pipe fitting and deform.
As an improvement of the invention, the convex rings are provided with an upper layer cavity and a lower layer cavity, a connecting edge is obliquely arranged between every two adjacent convex rings, a side cavity is formed between every two adjacent convex rings and the connecting edge and the sealing ring in a matching manner, and the upper layer cavity, the lower layer cavity and the side cavity are distributed in a honeycomb manner.
As a modification of the present invention, the protruding ring is provided obliquely in the direction of the second abutting portion.
As an improvement of the present invention, a tapered cavity with an opening facing the first abutting portion is disposed on the sealing ring, the cross-sectional area of the tapered cavity gradually decreases toward the second abutting portion, the expansion ring is in a circular truncated cone shape adapted to the tapered cavity, the expansion ring is disposed in the tapered cavity, when the first abutting portion abuts against the expansion ring, the expansion ring is driven to expand, and when the expansion ring expands, the expansion ring abuts against the inner wall of the tapered cavity, so that the sealing ring expands.
As an improvement of the invention, a connecting channel communicated with the inside of the pipe fitting is arranged on the first push rod, and the pressurizing loop and the pressure relief loop are communicated with the pipe fitting in the forming die through the connecting channel.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention.
Fig. 2 is a schematic structural diagram of the plug and the driving element of the present invention.
Fig. 3 is a cross-sectional view of fig. 2 of the present invention.
Fig. 4 is a partially enlarged view of fig. 3 a of the present invention.
Fig. 5 is a schematic view of the seal ring structure of the present invention.
Fig. 6 is a partially enlarged view of the invention at B of fig. 5.
FIG. 7 is a pressure loading path diagram for a pipe fitting during the rapid pressurization, wave forming, and high pressure shaping stages of the present invention.
FIG. 8 is a schematic diagram showing the displacement of the driving element pushing the plug to move during the pressure-releasing feeding phase according to the present invention.
Figure 9 is a schematic view of a tube of the present invention.
FIG. 10 is a schematic view of an intermediate-wave formed tube of the present invention.
FIG. 11 is a schematic view of a wave formed final end tube of the present invention.
Figure 12 is a schematic view of the tube of the present invention as it is being finish formed.
In the figure, 1, an upper die; 2. a lower die; 3. a seal ring; 3.1, a conical cavity; 3.2, a convex ring; 3.3, a ring groove; 3.4, connecting edges; 3.5, an upper cavity; 3.6, a lower cavity; 3.7, side cavity; 4. an expansion ring; 5. a first push rod; 5.1, a first abutting portion; 6. a second push rod; 6.1, a second abutment; 7. a circular plate; 8. a first hydraulic cylinder; 9. and a second hydraulic cylinder.
Detailed Description
The invention is further explained with reference to the drawings.
Referring to fig. 1 to 12, the multi-step Ω tube fluctuating internal high pressure forming process includes the following steps:
a. early preparation: respectively fixing and opening an upper die 1 and a lower die 2 of a forming die, then placing a pipe fitting into a cavity of the lower die 2, wherein the pipe fitting is provided with a plurality of areas to be formed, two ends of the forming die are provided with plugs and driving elements, and the driving elements push the plugs to move axially into the pipe fitting so that the plugs are positioned at two ends of one area to be formed and seal the two ends of the area to be formed;
b. and (3) rapid pressurization: pressurizing the pipe fitting by filling liquid through the plugUntil reaching the plastic deformation limit of the pipe fitting; referring to fig. 7, the loading path of the pipe fitting pressure is:
wherein P is the pressure on the pipe,
is constant, t is the time for loading the pipe,
≤t≤
the pressure changes in a monotone increasing function, and the pressure is increased from 0 to 0 monotone along with the increase of the pressurizing time
The pressurization time is up to
The pipe reaches the plastic deformation limit.
c. Wave forming: in the pressure forming stage, when the pressure is quickly increased to the plastic deformation limit of the pipe fitting, the pipe fitting is continuously pressurized according to a function curve of a pressure increasing stage in the wave forming period, so that the pipe fitting starts to expand, in the pressure releasing and material supplementing stage, after the pressure is increased for a certain time, the internal pressure of the pipe fitting is reduced to be below the plastic deformation limit, so that the material supplementing of the pipe fitting can be realized, meanwhile, as shown in fig. 8, a left plug and a right plug start to generate plastic deformation from the pipe fitting, a driving element pushes the plugs to move, axial force is applied to two ends of the pipe fitting through the displacement of the plugs, the axial force is gradually increased along with the time, the blank required by the expansion of the pipe fitting is timely supplemented, and the;
during the wave forming period, referring to fig. 7, the loading path for the pipe fitting pressure is:
wherein P is the pressure on the pipe,
to achieve pressure during the rapid pressurization period, t is the time for loading the pipe,
≤t≤
the pressure variation trend is a sine function, and the pressure is pressurized and released for multiple times in a circulating manner; with increasing pressurization time, the pressure is increased from
Is incremented to
Until the pipe fitting is expanded without material supplement; the pressure forming stage and the pressure releasing and material supplementing stage are circulated for multiple times to realize fluctuating loading, and the pressure time reaches
Then, the fluctuating loading period is completed; the pipe fitting can be expanded through pressurization, effective material supplementing can be achieved at low pressure, and the phenomenon that the wall thickness of the pipe fitting is excessively thinned due to ineffective material supplementing and continuous expansion, the forming quality of parts is affected, and even the pipe wall is broken and fails is avoided.
d. High-pressure shaping: after the wave loading period is finished, quickly pressurizing the pipe fitting to enable the pipe fitting to generate micro deformation to be attached to a forming die, so that the section forms a multi-stage omega pipe; during the high pressure shaping period, referring to fig. 7, the loading path for the pipe fitting pressure is:
wherein P is the pressure on the pipe,
is constant, t is the time for loading the pipe,
≤t≤
the pressure changes in a monotonous increasing function along with the increase of the pressurizing time, and the pressure is increased from
Is incremented to
The pressurization time is up to
And finishing the shaping of the pipe fitting.
e. And (3) repeated forming: c, relieving the pressure of the pipe fitting of the section to be formed, driving the two plugs to move in the same direction in the pipe fitting by the two driving elements until the two plugs move into two ends of the next section to be formed, sealing the two ends of the section to be formed, and repeating the step b, the step c and the step d in sequence; so that the section forms a multi-step omega tube; and repeating the steps to form all the areas to be formed until the final formed part meeting the requirement is formed.
In the forming process, during the material supplementing and forming stage, through wave forming, when the pressure is quickly increased to the plastic deformation limit of the pipe fitting, the pipe fitting is continuously pressurized, so that the pipe fitting starts to expand, after the pressure is increased for a certain time, the internal pressure of the pipe fitting is reduced to be below the plastic deformation limit, and meanwhile, the left plug and the right plug start to generate plastic deformation from the pipe fitting, axial force is applied to two ends of the pipe fitting, blanks required by expansion of the pipe fitting are timely supplemented, and excessive thinning caused by expansion of the pipe fitting is avoided; the pressure forming stage and the pressure releasing and material supplementing stage are circulated for multiple times to realize fluctuating loading, so that the pipe fitting can be expanded through pressurization, and effective material supplementing can be performed at low pressure, and the phenomenon that the wall thickness of the pipe fitting is excessively thinned due to ineffective material supplementing and continuous expansion, the forming quality of parts is influenced, and even the pipe wall is broken and fails is avoided; after the wave loading stage is finished, rapidly pressurizing the pipe fitting to enable the pipe fitting to generate micro deformation to be attached to a forming die to form a final forming part meeting the requirement, supplementing materials to a deformation region from an undeformed region in time through a wave loading path, and improving the forming quality and forming capacity of the deformation region; and by arranging the plugs and the driving element, after the multi-stage omega tube in one section is formed, the driving element drives the plugs to move to two ends of the next section to be formed to form the multi-stage omega tube, and the section distance formed by feeding each time is short by a sectional forming method, so that the feeding effect is good.
The two ends of the forming die are arranged in an opening manner, the plug comprises a sealing ring 3, an expansion ring 4, a circular plate 7, a first push rod 5 and a second push rod 6, the driving element comprises a first hydraulic cylinder 8 and a second hydraulic cylinder 9, a connecting channel is axially arranged on the first push rod 5, and the pressurizing loop and the pressure relief loop are communicated with a pipe fitting in the forming die through the connecting channel so as to pressurize and relieve the pressure of the pipe fitting; one end of the second push rod 6 is in transmission connection with the second hydraulic cylinder 9, a second abutting portion 6.1 is formed at the other end of the second push rod 6 in a protruding mode, the second push rod 6 is integrally rectangular frame-shaped, a containing portion is formed at the center of the second push rod 6, the first hydraulic cylinder 8 is arranged in the containing portion, one end of the first push rod 5 is in transmission connection with the first hydraulic cylinder 8, the other end of the first push rod 5 penetrates through the second abutting portion 6.1 and protrudes to form a first abutting portion 5.1, and the first abutting portion 5.1 and the second abutting portion 6.1 are coaxially arranged.
The sealing ring 3, the expansion ring 4 and the circular plate 7 are sequentially sleeved on the first push rod 5 and are positioned between the first abutting part 5.1 and the second abutting part 6.1, and the first push rod 5 is provided with a stopping part matched with the circular plate 7, so that when the first push rod 5 moves, the sealing ring 3, the expansion ring 4 and the circular plate 7 can be driven to move simultaneously.
Be equipped with the opening on sealing washer 3 towards the toper chamber 3.1 of first butt portion 5.1, the cross-sectional area in toper chamber 3.1 reduces gradually towards second butt portion 6.1 direction, expansion ring 4 is the round platform form with toper chamber 3.1 looks adaptation, expansion ring 4 set up in the toper chamber 3.1, expansion ring 4 is equipped with the toper opening towards first butt portion 5.1, and the cross-sectional area of toper opening reduces gradually towards second butt portion 6.1 direction, first butt portion 5.1 periphery is the toper.
When sealing, the first hydraulic cylinder 8 pushes the first push rod 5 to extend out, the sealing ring 3, the expansion ring 4 and the circular plate 7 are pushed into a pipe fitting in a forming die, the second hydraulic cylinder 9 pushes the second push rod 6 to move, so that the second abutting part 6.1 pushes the circular plate 7 to abut against the sealing ring 3, the sealing ring 3 is limited, the sealing ring 3 is prevented from moving towards the second abutting part 6.1, the first hydraulic cylinder 8 drives the first push rod 5 to retract, so that the first abutting part 5.1 pushes the expansion ring 4 to abut against, during the movement of the first abutting part 5.1, the first abutting part 5.1 partially extends into the tapered opening, the cross-sectional area of the tapered opening is gradually reduced, the expansion ring 4 is driven to axially move and radially expand, during the axial movement and radially expand of the expansion ring 4, the cross-sectional area of the tapered cavity 3.1 is gradually reduced, thereby driving the sealing ring 3 to expand radially to seal the end part of the pipe fitting.
In the axial retraction movement process of the first abutting part 5.1, the cross section area of the conical opening is gradually reduced, so that the expansion ring 4 is easy to axially move and radially expand, in the axial movement and radial expansion process of the expansion ring 4, the cross section area of the conical cavity 3.1 is gradually reduced, and the other end of the sealing ring 3 is limited and fixed by the circular plate 7, so that the sealing ring 3 is easy to radially expand, and the end part of the pipe fitting is sealed.
The 3 peripheral surfaces of sealing washer are equipped with a plurality of bulge loops 3.2, and are a plurality of bulge loops 3.2 set up along axial interval, are formed with annular 3.3 between two adjacent bulge loops 3.2, bulge loop 3.2 is towards the direction slope setting of second butt portion 6.1. Have upper cavity 3.5 and lower floor's cavity 3.6 on the bulge loop 3.2, adjacent two the slope is provided with between the bulge loop 3.2 and connects limit 3.4, adjacent two bulge loop 3.2, connect limit 3.4 with the cooperation is formed with side cavity 3.7 between the sealing washer 3, in addition the cross-section of upper cavity 3.5, lower floor's cavity 3.6 and side cavity 3.7 all is the wedge, makes bulge loop 3.2 easily takes place to warp.
Because the inside undulant pressure that receives of pipe fitting, undulant pressure change is great moreover, if directly sealed through sealing washer 3, undulant power can transmit to sealing washer 3, and sealing washer 3 can receive undulant axial force, can promote sealing washer 3 and remove, influences sealed effect, can cause sealing washer 3 to take place to warp moreover, influences sealed effect. The sealing ring can generate axial thrust to the sealing ring 3 by arranging the first abutting part 5.1, the second abutting part 6.1 and the second hydraulic cylinder 9, so that the sealing ring 3 can keep balance with fluctuating axial power, the sealing ring 3 can not move, the bulge loop 3.2 which is easy to deform is arranged on the periphery of the sealing ring 3, the bulge loop 3.2 can be tightly attached to the inner wall of the pipe fitting, the bulge loop 3.2 is obliquely arranged and can be conveniently and tightly abutted to the inner wall of the pipe fitting, after the sealing ring 3 is subjected to axial action, when the sealing ring 3 deforms, the bulge loop 3.2 can still be tightly attached to the inner wall of the pipe fitting, the contact area between the sealing ring 3 and the inner wall of the pipe fitting is increased, good sealing performance is ensured, the annular grooves 3.3 are formed between the two adjacent bulge loops 3.2 at intervals, the annular grooves 3.3 can play a role in storage, when water leaks from the pipe fitting, can store the water of leaking through annular 3.3, avoid water to leak to external world to guarantee sealing washer 3's sealed effect. The upper-layer cavity 3.5, the lower-layer cavity 3.6 and the side cavities 3.7 are distributed in a honeycomb shape, so that after the convex ring 3.2 deforms, the convex ring 3.2 and the side cavities generate larger reaction force, the convex ring 3.2 can be always in tight contact with the inner wall of the pipe fitting, after the sealing ring 3 receives the axial action force fluctuating in the pipe fitting, the convex ring 3.2 can still be tightly attached to the inner wall of the pipe fitting, and the sealing requirement can be met. In addition, when the two driving elements drive the two plugs to move in the same direction in the pipe fitting to the two ends of the section to be formed, the convex rings 3.2 on the sealing rings 3 in the two plugs are always in a deformation state and can be always abutted against the inner wall of the pipe fitting to keep a sealing state, and after the two plugs move to the two ends of the section to be formed, the two plugs directly pressurize the inside of the pipe fitting through the plugs to form the section.
In addition, when the pipe fitting in the forming die is subjected to plastic deformation, the driving element applies axial force to the two ends of the pipe fitting through the plugs, so that the end part of the pipe fitting is pushed to supplement materials to the bulging area, namely the first driving element and the second driving element act simultaneously to push the sealing ring 3 to axially move in the pipe fitting, and when the sealing ring 3 axially moves, the convex ring 3.2 can still be tightly attached to the inner wall of the pipe fitting, so that good sealing performance is ensured.
The above description is only a preferred embodiment of the present invention, and all equivalent changes or modifications of the structure, characteristics and principles described in the present invention are included in the scope of the present invention.
Claims (8)
1. The multi-stage omega tube fluctuation internal high-pressure forming process is characterized in that: the method comprises the following steps:
a. early preparation: placing the pipe fitting into a corresponding forming die, and closing the forming die, wherein the pipe fitting is sequentially provided with a plurality of sections to be formed along the axial direction, two ends of the forming die are respectively provided with a plug and a driving element, and the driving element pushes the plugs to move into the pipe fitting axially so that the two plugs are positioned at two ends of one section to be formed and seals the two ends of the section to be formed;
b. and (3) rapid pressurization: and (3) charging and pressurizing the pipe fitting of the section to be formed through the plug until the limit of plastic deformation of the pipe fitting is reached, wherein the loading path of the pressure of the pipe fitting is as follows:
wherein P is the pressure on the pipe,
is a constant, t is the loading time of the pipe fitting;
c. wave forming:
in the pressure forming stage, when the pressure is quickly increased to the plastic deformation limit of the pipe fitting, the pipe fitting is continuously pressurized, so that the pipe fitting begins to expand;
in the pressure relief and material supplementing stage, after the pipe fitting is pressurized and expanded, the pressure of the pipe fitting is relieved, so that the internal pressure of the pipe fitting is reduced to be below a plastic deformation limit, and the pipe fitting can be supplemented with materials;
the pressurization forming stage and the pressure relief material supplementing stage are circulated for multiple times to realize fluctuating loading, and the loading path of the pressure of the pipe fitting is as follows:
wherein P is the pressure on the pipe,
is the pressure reached during the rapid pressurization period, t is the time to load the pipe;
d. high-pressure shaping: after the fluctuating loading period is finished, the pipe fitting is quickly pressurized, so that the pipe fitting generates micro deformation to be attached to a forming die, a multi-stage omega pipe is formed in the section, and the loading path of the pressure of the pipe fitting is as follows:
wherein P is the pressure on the pipe,
is a constant, t is the loading time of the pipe fitting;
e. and (3) repeated forming: c, relieving the pressure of the pipe fitting of the section to be formed, driving the two plugs to move in the same direction in the pipe fitting by the two driving elements until the two plugs move into two ends of the next section to be formed, sealing the two ends of the section to be formed, and repeating the step b, the step c and the step d in sequence; so that the section forms a multi-step omega tube; and repeating the steps to form all the areas to be formed until the final formed part meeting the requirement is formed.
2. The multi-step omega tube fluctuating internal high pressure forming process of claim 1, wherein: in the pressure relief and material supplement stage, when the pipe fitting generates plastic deformation, the driving element applies axial force to the two ends of the pipe fitting through the two plug heads so as to supplement the blank required by the expansion of the pipe fitting.
3. The multi-step omega tube fluctuating internal high pressure forming process of claim 1, wherein: the plug comprises a sealing ring, an expansion ring, a circular plate, a first push rod and a second push rod, and the driving element comprises a first hydraulic cylinder and a second hydraulic cylinder;
one end of the second push rod is in transmission connection with the second hydraulic cylinder, the other end of the second push rod protrudes to form a second abutting part, an accommodating part is further formed on the second push rod, the first hydraulic cylinder is arranged in the accommodating part, one end of the first push rod is in transmission connection with the first hydraulic cylinder, the other end of the first push rod penetrates through the second abutting part and protrudes to form a first abutting part, the first abutting part and the second abutting part are coaxially arranged, and the sealing ring, the expansion ring and the circular plate are sequentially sleeved on the first push rod and are positioned between the first abutting part and the second abutting part;
in the step a, the two first hydraulic cylinders respectively push the first push rods to extend out, the sealing ring and the expansion ring are pushed into the pipe fitting in the forming die, the second hydraulic cylinder pushes the second push rod, the circular plate is pushed to abut against the sealing ring, the first hydraulic cylinder drives the first push rod to retract, the first push rod abuts against the expansion ring through the stop block, so that the expansion ring is expanded, the sealing ring is driven to expand when the expansion ring is expanded, and the sealing ring is attached to the inner wall of the pipe fitting, so that the pipe fitting is sealed;
in the step e, the two first driving elements at the two ends of the forming die respectively drive the first push rods to move in the same direction in the pipe fitting, and the two second driving elements respectively drive the second push rods to move in the same direction in the pipe fitting, so that the two plugs move to the two ends of the next section to be formed.
4. The multi-step omega tube fluctuating internal high pressure forming process of claim 3, wherein: the sealing washer periphery is equipped with a plurality of bulge loops, and is a plurality of the bulge loop sets up along axial interval for be formed with the annular between two adjacent bulge loops, work as the sealing washer back that rises, the bulge loop offsets and takes place to warp with the pipe fitting inner wall.
5. The multi-step omega tube fluctuating internal high pressure forming process of claim 4, wherein: the upper cavity and the lower cavity are arranged on the convex rings, the connecting edges are arranged between the adjacent two convex rings in an inclined mode, the adjacent two convex rings, the connecting edges and the sealing rings are matched to form side cavities, and the upper cavity, the lower cavity and the side cavities are distributed in a honeycomb mode.
6. The multi-step omega tube fluctuating internal high pressure forming process of claim 5, wherein: the cross sections of the upper layer cavity, the lower layer cavity and the side cavity are all wedge-shaped.
7. The multi-step omega tube fluctuating internal high pressure forming process of claim 4, wherein: be equipped with the opening on the sealing washer and towards the toper chamber of first butt portion, the cross-sectional area in toper chamber reduces towards second butt portion direction gradually, the expansion ring is the round platform form with toper chamber looks adaptation, the expansion ring set up in the toper chamber, first butt portion with when the expansion ring offsets, drive the expansion ring is expanded, thereby the in-process that the expansion ring was expanded offsets with toper intracavity wall makes the sealing washer is expanded.
8. The multi-step omega tube fluctuating internal high pressure forming process of claim 3, wherein: and a connecting channel communicated with the inside of the pipe fitting is arranged on the first push rod.
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