CN113145716B - Two-piece one-die forming method for mutually symmetrical characteristic parts - Google Patents
Two-piece one-die forming method for mutually symmetrical characteristic parts Download PDFInfo
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- CN113145716B CN113145716B CN202110319760.9A CN202110319760A CN113145716B CN 113145716 B CN113145716 B CN 113145716B CN 202110319760 A CN202110319760 A CN 202110319760A CN 113145716 B CN113145716 B CN 113145716B
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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
- B21D26/021—Deforming sheet 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
- B21D26/021—Deforming sheet bodies
- B21D26/027—Means for controlling fluid parameters, e.g. pressure or temperature
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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
- B21D26/021—Deforming sheet bodies
- B21D26/031—Mould construction
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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
- B21D37/00—Tools as parts of machines covered by this subclass
- B21D37/18—Lubricating, e.g. lubricating tool and workpiece simultaneously
Abstract
The invention provides a two-piece one-die forming method for mutually symmetrical characteristic parts, which belongs to the technical field of gas forming and aims to solve the problems that large aluminum alloy skin covering parts used in the existing train are long in research and development period and high in manufacturing cost during forming and part forming quality is difficult to ensure.
Description
Technical Field
The invention belongs to the technical field of gas forming, and particularly relates to a two-piece one-die forming method for mutually symmetrical characteristic pieces.
Background
In order to facilitate the increasing travel demands of people, more and more cities begin to build and perfect a radiation traffic network from a central city area to a peripheral area, and rail lines connect thousands of households and simultaneously provide light-weight and environment-friendly requirements for the supply of rail transit vehicles. At present, the materials adopted by the urban rail train skin based on the principle of light weight mainly comprise glass fiber reinforced plastics and aluminum alloy, wherein the glass fiber reinforced plastics are also called glass fiber reinforced plastics, have the characteristics of easiness in forming and good designability, can ensure the manufacturing and production of complex vehicle body shapes, but are difficult to recycle, and have high maintenance cost in the service life cycle and short overall service life; the aluminum alloy can avoid maintenance, the material is convenient to recover and remelt, but when the aluminum alloy is used for manufacturing the train skin with the complex shape, the forming process is difficult to determine, and the quality is difficult to ensure. When the aluminum alloy material is adopted, a hot stamping process is usually adopted in the traditional method, the springback error is reduced by means of die design adjustment and manual shape correction, and the process for the more and more complex vehicle body skin is increasingly strenuous. In recent years, with the research of scholars at home and abroad, some aluminum alloys have superplasticity, namely, the property that the elongation rate reaches more than 200% under specific forming conditions on the premise of meeting the requirements of cost and use, and the yield limit of the material is only dozens of megapascals at the time, and the rebound resilience can be ignored, so that the application of the superplastic forming method to the rail vehicle covering part is gradually popularized.
Superplastic forming often requires ensuring that the material flows horizontally at relatively low strain rates, and the use of pneumatic or hydraulic controls is an effective means. The fixture for superplastic forming comprises an upper die and a lower die, wherein a plate to be formed is arranged between the upper die and the lower die, and holes are arranged on the upper die and the lower die to control gas to flow in and out. And after the tool is assembled, the workpiece is placed in a hearth of a press machine and heated to a target temperature, after edge sealing force is applied to guarantee sealing, the inflow speed of gas is controlled to guarantee a target strain rate, pressure is maintained for a period of time after the workpiece is completely adhered to a die, and the workpiece is taken out to obtain the target part.
At present, china is in the transition period from a glass fiber reinforced plastic vehicle body to an aluminum alloy vehicle body, and urgent requirements are put forward on the process formulation and the die design of a large-scale integrated aluminum alloy train skin piece. The bilateral symmetry is a characteristic of rail transit vehicles, and the artistic requirements of symmetry and beauty are met, so that the stress balance of the whole train body is kept, and the stability of a train running at high speed is ensured. For the bilateral symmetry structure, the bilateral symmetry structure is usually symmetrical about the central axis plane of the train and does not have the symmetry characteristic, so that two sets of dies are needed to be adopted during part forming, the cost is greatly improved, and the method for forming the two symmetrical characteristic parts by one die is provided for solving the problems.
Disclosure of Invention
The invention aims to solve the problems that the development cycle is long, the manufacturing cost is high and the part forming quality is difficult to ensure when a large aluminum alloy skin covering piece used in the existing train is formed, and further provides a two-piece one-die forming method for mutually symmetrical characteristic parts;
a two-piece, one-die forming method for symmetrical features of each other, said method comprising the steps of:
the method comprises the following steps: designing a mold: aiming at two shallow-cavity large aluminum alloy skin covering parts with symmetrical spatial planes, an upper die is firstly designed, the size of a cavity is determined according to the surface shape of a part by considering the effect of expansion with heat and contraction with cold, and the edge sealing platform is completely positioned on a plane parallel to the table surface of a press machine, the basic shape of a lower die can be obtained through mirror symmetry about the plane, on the basis, staggered edge sealing grooves are respectively formed in the edge sealing platforms in the upper die and the lower die, a plurality of guide mechanisms are arranged on the circumferential direction of the upper die and the lower die, each guide mechanism comprises a positioning guide rail and a guide block, the positioning guide rails are fixedly connected to the outer wall of the lower die, the guide blocks are fixedly connected to the outer wall of the upper die, positioning reference blocks are arranged at the corners of the upper die and the lower die, a plurality of thermocouple holes are respectively formed in the circumferential direction in the outer wall of the upper die and the outer wall of the lower die, a plurality of weight reducing grooves are respectively formed in the circumferential direction in the outer wall of the upper die and the edge sealing platforms in the lower die, and an air inlet through hole is respectively formed in the corresponding positions of the upper die and the lower die;
step two: loose piece design: designing a loose piece structure according to the depth and local characteristics of the shallow cavity in the large aluminum alloy skin covering part, and ensuring that the loose piece can be arranged in the cavity matched with the shallow cavity in the large aluminum alloy skin covering part on the die in the step one;
step three: raw material blanking: cutting and blanking by using a plate cutting machine according to the calculated size of the flat plate, and efficiently and uniformly spraying graphite emulsion on the upper surface of the plate by adopting an air compressor and an air pressure regulating device to be connected with a spray can containing lubricating liquid;
step four: early preparation: fixing the upper die in the first step on an upper platform of a press machine, ensuring the upward die attaching direction of a plate, fixing the lower die provided with a movable block on a lower platform of the press machine by using a pressing plate, heating to a target temperature, then placing the plate, preserving heat to ensure that the plate is fully heated, and applying a die closing force for many times by using a hydraulic cylinder after softening to maintain pressure so that edge sealing materials fully flow into an edge sealing groove;
step five: gas forming: filling gas into the die fixed on the upper platform of the press in the fourth step, so that the plate arranged in the die in the fourth step deforms under the action of air pressure and is gradually attached to the cavity structure of the upper die;
step six: taking out the parts: in the final die-attaching and pressure-maintaining stage, an air inlet through hole in an upper die is connected with a vacuum pump, the pump is opened in the workpiece taking stage to exhaust gas in a cavity, the pump is closed after the die of the press is opened, and a crowbar is used for applying force through a jaw to complete part demoulding;
step seven: product treatment: after the temperature is reduced to room temperature, rough cutting and fine cutting are carried out on parts, and chemical and physical surface treatment is respectively carried out on the parts, so that one of the shallow cavity large curved surface aluminum alloy skin parts with high shape precision is obtained, the symmetrical direction part is just required to be inverted, and other processes are not changed, so that the effect of one mould for two parts can be achieved;
further, the depth of a shallow cavity arranged in the large and medium aluminum alloy skin covering piece in the first step is less than 200mm;
furthermore, in the die structure in the first step, both the upper die and the lower die need to be provided with air inlet through holes, the plane of the edge sealing platform is parallel to the platform of the press machine, square edge sealing grooves need to be designed on both the upper die and the lower die, the two edge sealing grooves need to be arranged in a staggered manner, the staggered horizontal distance needs to be more than 8mm, and a jaw is designed on the edge sealing platform in the upper die and the edge sealing platform in the lower die at intervals of 400 mm;
further, the loose piece in the second step is roughly processed with volume filler or finely processed cavity entity;
further, the plate in the third step is left with plate allowance of 40-60 mm, and after the graphite emulsion is completely sprayed to the upper surface, the plate is kept stand for 12 minutes to ensure that the graphite emulsion is stably attached;
further, in the fourth step, the temperature rising speed of the press is 2 ℃ per minute on average, the forming temperature is 460-520 ℃, the temperature of the plate is kept for 15 minutes after the plate is placed in the press, and the edge sealing hydraulic pressure of a hydraulic cylinder of the press is 15-22 MPa;
further, in the fifth step, argon or nitrogen is filled into the die fixed on the upper platform of the press in the fourth step, and the temperature of the filled gas is 30-40 ℃:
further, the working process of filling gas into the mold fixed on the press in the fourth step is to fill gas into the gas inlet through hole in the upper mold for preforming, and then fill gas into the gas inlet through hole in the lower mold for final forming;
further, the working process of filling gas into the die fixed on the press machine in the step four in the step five is to directly fill gas into a gas inlet through hole in the lower die for final forming;
further, the process in the step five is controlled according to the curve of the numerical simulation result during gas forming, the reverse expansion pressure is less than 1.5MPa, the final expansion pressure is less than 3MPa, and the pressure maintaining time after the maximum pressure is reached is more than 30 minutes;
further, the process in the step five is controlled according to a curve of a numerical simulation result during gas forming, the final expansion pressure is less than 3MPa, and the pressure maintaining time after the maximum pressure is reached is more than 30 minutes;
further, after the pressure maintaining is finished and before the pressure is released in the sixth step, the air inlet through hole in the upper die is connected with a vacuum pump, when the vacuum degree is below 10000Pa, the suction force is kept, the pump is closed after the gas is exhausted, and the part demoulding is realized under the dual actions of the self gravity of the part and the prying force of the jaw;
and further, after the part in the seventh step is taken out, the molded surface of the part is accurately cut according to a three-dimensional digital-analog drawing, surface oxidation substances are removed through acid washing and alkali washing, and surface dirt is removed through a flat diaphragm machine, so that one of the shallow-cavity large-scale curved-surface aluminum alloy skin parts with high shape precision is obtained.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a two-piece one-die forming method for symmetrical characteristic pieces, and provides a one-die two-cavity tool for a symmetrical double-side shallow-cavity complex-shaped aluminum alloy covering piece of a vehicle, a matched die and a matched processing method.
2. The invention provides a two-piece one-die forming method for mutually symmetrical characteristic parts, which adopts the design of a loose piece, on one hand, the requirement of the loose piece on the processing precision is not high, the manufacturing cost is low, but the space can be effectively filled in the gas expansion process to accelerate the gas filling speed, the production efficiency is improved, and a large amount of gas waste under high-pressure long-time pressure maintaining is inhibited; on the other hand, according to the changeable characteristic shape of the target part, the structural shape of the movable block can be flexibly manufactured, the movable block is firstly attached to the movable block in a reverse expansion mode to store materials, then the wall thickness of the position with serious local thinning is improved in a forward expansion mode, and the defect is avoided positively.
3. The invention provides a two-piece one-die forming method for mutually symmetrical characteristic parts, wherein air inlets related in a die can also be used as air extraction holes, so that the shape precision of parts is not influenced when the parts are taken.
Drawings
FIG. 1 is a schematic diagram of the method of the present invention;
FIG. 2 is a schematic view of an upper mold used in the method of the present invention;
FIG. 3 is a schematic view of a lower mold used in the method of the present invention;
FIG. 4 is a schematic view of a matched mold in the method of the present invention;
in the figure, an upper die 1, a plate 2, a loose block 3, a lower die 4, an air inlet 5, a sealing edge platform 6, a sealing edge groove 7, a guide mechanism 8, a positioning reference block 9, a thermocouple hole 10 and a jaw 11 are arranged.
Detailed Description
The first embodiment is as follows: the present embodiment is described with reference to fig. 1 to 4, and provides a two-piece, one-die forming method for symmetrical features of each other, by the steps of:
the method comprises the following steps: designing a mold: aiming at two shallow-cavity large aluminum alloy skin covering parts with symmetrical spatial planes, an upper die 1 is firstly designed, the size of a cavity is determined by considering the effect of expansion with heat and contraction with cold according to the surface shape of a part, and a sealing edge platform 6 is completely positioned on a plane parallel to the table surface of a press machine, the basic shape of a lower die 4 can be obtained by mirror symmetry about the plane, on the basis, staggered sealing edge grooves 7 are respectively formed in the sealing edge platforms 6 in the upper die 1 and the lower die 4, a guide mechanism 8, a positioning reference block 9, a thermocouple hole 10, a weight reduction groove and a jaw 11 are arranged, and an air inlet through hole 5 is respectively formed in the corresponding positions of the upper die 1 and the lower die 4;
step two: loose piece design: designing a loose piece structure according to the depth and local characteristics of a shallow cavity in the large aluminum alloy skin covering piece, and ensuring that the loose piece 3 can be arranged in a cavity which is matched with the shallow cavity in the large aluminum alloy skin covering piece on the die in the step one;
step three: blanking raw materials: cutting and blanking by using a plate cutting machine according to the calculated size of the flat plate, and efficiently and uniformly spraying graphite emulsion on the upper surface of the plate by adopting an air compressor and an air pressure regulating device to be connected with a spray can containing lubricating liquid;
step four: early preparation: fixing the upper die 1 in the first step on an upper platform of a press machine, ensuring the upward die attaching direction of a plate 2, fixing a lower die 4 provided with a movable block 3 on a lower platform of the press machine by using a pressing plate, heating to a target temperature, then placing the plate, preserving heat to fully heat the plate, and after softening, applying a die closing force by using a hydraulic cylinder for multiple times to preserve heat, so that edge sealing materials fully flow into an edge sealing groove;
step five: gas forming: filling gas into the die fixed on the upper platform of the press in the fourth step, so that the plate 2 arranged in the die in the fourth step deforms under the action of air pressure and is gradually attached to the cavity structure of the upper die 1;
step six: taking out the parts: in the final die-attaching and pressure-maintaining stage, an air inlet through hole 5 on the upper die 1 is connected with a vacuum pump, the pump is opened in the workpiece taking stage to discharge gas in the cavity, the pump is closed after the die of the press is opened, and a crowbar is used for applying force through a jaw 11 to complete part demoulding;
step seven: product treatment: and after the temperature is reduced to room temperature, roughly cutting and finely cutting parts, and respectively carrying out chemical and physical surface treatment to obtain one of the shallow cavity large curved surface aluminum alloy skin parts with high shape precision, wherein the symmetrical parts only need to be inverted by a mould, and other processes are not changed, so that the effect of one mould for two parts can be achieved.
In the embodiment, through improvement on the die, cavities to be formed are processed on an upper die 1 and a lower die 4 in the existing die, and a movable block 3 is arranged in the cavity on one side, so that on one hand, the movable block 3 has low manufacturing cost for processing precision, but can effectively fill space in the gas expansion process to accelerate gas filling speed, improve production efficiency and inhibit a large amount of gas waste under high-pressure long-time pressure maintaining; on the other hand, according to the changeable characteristic shape of the target part, the structural shape of the loose piece 3 can be flexibly manufactured, the loose piece is firstly attached to the reverse expansion for storing materials, and then the wall thickness of the position with serious local thinning is improved through the forward expansion, so that the defect is avoided, and the position of the loose piece 3 is worth noting that the air inlet hole area in the mold is not blocked;
the method has the forming principle that two sides are respectively formed, supposing that the large-scale shallow-cavity aluminum alloy skin A and the large-scale shallow-cavity aluminum alloy skin B are two parts (such as a left vehicle door and a right vehicle door) which are symmetrical about a space plane and have no symmetrical characteristic, firstly, the part A is produced in batch, the cavity A is arranged above the cavity A, the loose block is arranged in the cavity B below the cavity A, the pressure is applied after the same plate material in a hearth of a press machine is heated to superplastic temperature, and after the plate material at the edge sealing position is ensured to fully flow into an edge sealing groove, the pressure and the heat preservation are carried out; then gas is introduced from the gas inlet hole of the die cavity B, meanwhile, the gas hole of the die cavity A also has the function of exhausting, the movable block has the functions of occupying volume and saving gas, and the change of gas expansion pressure is controlled to ensure that the plates are completely attached to the die; and finally, releasing gas pressure, and completing demoulding under the action of the self gravity of the part and the pressure of the jaw crowbar after the mould is opened, so that the thermal shape of the part can be further ensured, and meanwhile, the part A can be produced by vacuumizing through the air hole of the cavity B. Similarly, after the die is turned upside down, the batch manufacturing of the B pieces can be completed by the same process and flow.
The second embodiment is as follows: the present embodiment is described with reference to fig. 1 to 4, which further define the first step described in the first embodiment, in which the depth of the shallow cavity provided in the large aluminum alloy skin covering is less than 200mm. Other components and connection modes are the same as those of the first embodiment.
So set up, consider the range of application of gas forming, if the shallow chamber degree of depth of will be too big, gas forming is difficult to satisfy the requirement, can lead to along with the continuous inflation of gas simultaneously, and the regional atress in the shallow chamber is uneven in large-scale aluminum alloy skin covering, easily influences the shaping effect.
The third concrete implementation mode: the embodiment is described with reference to fig. 1 to 4, and is further limited to the first step described in the second embodiment, in the structure of the mold in the first step, the upper mold 1 and the lower mold 4 need to be provided with the air inlet through hole 5, the plane of the edge sealing platform 6 is parallel to the press platform, square edge sealing grooves need to be designed on the upper mold 1 and the lower mold 4, the two edge sealing grooves need to be arranged in a staggered manner, the horizontal distance of the staggered manner needs to be more than 8mm, and a jaw 11 is designed on the edge sealing platform 6 in the upper mold 1 and the edge sealing platform 6 in the lower mold 4 at intervals of 400 mm. The other components and the connection mode are the same as those of the second embodiment.
Due to the arrangement, the staggered arrangement of the edge sealing grooves in the two dies can effectively ensure that the plate material fully flows into the upper edge sealing groove and the lower edge sealing groove, so that both sides of the plate material have good airtight effects; the jaws 11 arranged at equal intervals on the edge sealing platform 6 are matched, so that the formed workpiece is separated from the die conveniently, and the workpiece is taken efficiently.
The fourth concrete implementation mode: the present embodiment will be described with reference to fig. 1 to 4, and is further limited to the second step described in the third embodiment, and in the present embodiment, the loose piece 3 in the second step is a rough volume filler or a finished solid cavity. Other components and connection modes are the same as those of the third embodiment.
In this embodiment, the loose piece 3 can be flexibly adjusted according to the shape of the part: the volume filler can be roughly processed, so that the gas waste in batch production can be effectively inhibited, and the production efficiency can be improved; the die cavity entity can also be subjected to finish machining, the reverse expansion degree is controlled, and the local excessive thinning and cracking are avoided.
The fifth concrete implementation mode: the present embodiment is described with reference to fig. 1 to 4, and the present embodiment further defines the third step in the fourth embodiment, in the third step, a sheet margin of 40 to 60mm is left on the sheet 2, and after the graphite emulsion is completely sprayed to the upper surface, the sheet is left standing for 12 minutes to ensure that the graphite emulsion is stably attached. Other components and connection modes are the same as those of the fourth embodiment.
So set up, make graphite emulsion stable attached on panel surface, be favorable to panel 2 to have good drawing of patterns lubricating property after shaping, make the part drawing of patterns easier.
The sixth specific implementation mode: the fourth step is further limited to the fourth step described in the fifth embodiment, in the fourth step, the temperature rise speed of the press is 2 ℃ per minute on average, the forming temperature is 460 to 520 ℃, the temperature of the plate 2 is kept for 15 minutes after being placed in the press, and the edge sealing liquid pressure of the hydraulic cylinder of the press is 15 to 22MPa. The other components and the connection mode are the same as the fifth embodiment mode.
The seventh embodiment: the present embodiment will be described with reference to fig. 1 to 4, and the present embodiment is further limited to the fifth step described in the sixth embodiment, in the fifth step, argon or nitrogen is filled into the mold fixed to the upper platen of the press machine in the fourth step, and the temperature of the filled gas is 30 to 40 ℃. Other components and connection modes are the same as those of the sixth embodiment.
So set up, the direct gaseous temperature that flows out from the liquid nitrogen bottle of following of normal conditions is often extremely low, need let in the die cavity through the intake pipe again behind many bends long-range buffer, has increased the stroke of gas flow, has consumed more part shaping time.
The specific implementation mode is eight: the present embodiment is described with reference to fig. 1 to 4, and is further limited to the step five described in the seventh embodiment, and in the present embodiment, the working process of filling gas into the die fixed to the press in the step four in the step five includes filling gas into the gas inlet through hole 5 in the upper die 1 for performing, and then filling gas into the gas inlet through hole 5 in the lower die 4 for final forming. The other components and the connection mode are the same as those of the seventh embodiment.
Due to the arrangement, the joint rate of the formed part and the die is favorably ensured, the smoothness of the surface profile of the formed part is favorably ensured, and the method is suitable for the condition that the depth of a shallow cavity in the formed workpiece is deep (the depth is between 100mm and 200 mm).
The specific implementation method nine: the present embodiment is described with reference to fig. 1 to 4, and is further limited to the fifth step of the specific embodiment, in the present embodiment, the working process of filling gas into the die fixed to the press in the fourth step is to directly fill gas into the gas inlet hole 5 in the lower die 4 for final forming. The other components and the connection mode are the same as those of the eighth embodiment.
By adopting the method, the time for forming the workpiece can be reduced, and the method is suitable for the condition that the depth of the shallow cavity in the formed workpiece is shallow (the depth is between 0mm and 100 mm).
The specific implementation mode is ten: this embodiment will be described with reference to fig. 1 to 4, and this embodiment is further limited to the fifth step of the eighth embodiment, in which the process in the gas forming in the fifth step is controlled according to the curve of the numerical simulation result, the counter expansion pressure is less than 1.5MPa, the final expansion pressure is less than 3MPa, and the dwell time after the maximum pressure is reached is more than 30 minutes. The other components and the connection mode are the same as those of the eighth embodiment.
The concrete implementation mode eleven: the present embodiment is described with reference to fig. 1 to 4, and is further limited to the step five described in the specific embodiment eight, in the present embodiment, the process in the step five during gas forming is controlled according to the curve of the numerical simulation result, the final inflation pressure is less than 3MPa, and the dwell time after the maximum pressure is reached is more than 30 minutes. Other components and connection modes are the same as those of the eighth embodiment.
The detailed implementation mode is twelve: the present embodiment is described with reference to fig. 1 to 4, and the present embodiment further defines the sixth step of the specific embodiment, in the present embodiment, after the pressure holding in the sixth step is finished and before the pressure is released, the air inlet through hole 5 in the upper mold 1 is connected to a vacuum pump, when the vacuum degree is less than 10000Pa, the suction force is maintained, after the gas is exhausted, the vacuum pump is closed, and the demolding of the part is realized under the dual action of the self-gravity of the part and the prying force of the jaw 11. Other components and connection modes are the same as those of the eighth embodiment.
This arrangement is intended to relieve the gas pressure and facilitate the mold releasing step.
The specific implementation mode is thirteen: the present embodiment is described with reference to fig. 1 to 4, and the present embodiment further defines the seventh step of the eighth embodiment, in the present embodiment, after the part is taken out in the seventh step, the molded surface of the part is precisely cut according to the three-dimensional digital-analog drawing, the surface oxidation substance is removed by acid washing and alkali washing, and the surface fouling is removed by a flat-plate vibrating membrane machine, so as to obtain one of the shallow-cavity large-scale curved surface aluminum alloy skin parts with high shape precision, and other components and connection modes are the same as those of the eighth embodiment.
The present invention is not limited to the above embodiments, and any person skilled in the art can make many modifications and equivalent variations by using the above-described structures and technical contents without departing from the scope of the present invention.
Claims (13)
1. A two-piece one-die forming method for mutually symmetrical characteristic parts is characterized by comprising the following steps: the method is carried out by the following steps:
the method comprises the following steps: designing a mold: aiming at two large aluminum alloy skin covering pieces with shallow cavities and symmetrical space planes, an upper die (1) is firstly designed, determining the size of a cavity according to the surface shape of a part by considering the effect of expansion with heat and contraction with cold, ensuring that the edge sealing platform (6) is completely positioned on a plane parallel to the table surface of the press, obtaining the shape of the lower die (4) by mirror symmetry about the plane, respectively arranging staggered edge sealing grooves (7) on the edge sealing platform (6) in the upper die (1) and the lower die (4), a plurality of guide mechanisms (8) are arranged on the circumferential direction of the upper die (1) and the lower die (4), each guide mechanism (8) comprises a positioning guide rail and a guide block, the positioning guide rail is fixedly connected on the outer wall of the lower die (4), the guide block is fixedly connected on the outer wall of the upper die (1), a positioning reference block (9) is arranged at the corner of the upper die (1) and the lower die (4), a plurality of thermocouple holes (10) are respectively processed on the outer wall of the upper die (1) and the outer wall of the lower die (4) along the circumferential direction, a plurality of weight reduction grooves are respectively processed on the outer wall of the upper die (1) and the outer wall of the lower die (4) along the circumferential direction, a plurality of jaws (11) are respectively processed on edge sealing platforms (6) in the upper die (1) and the lower die (4), and air inlet through holes (5) are respectively formed in the corresponding positions of the upper die (1) and the lower die (4);
step two: loose piece design: designing a loose piece structure according to the depth and local characteristics of the shallow cavity in the large aluminum alloy skin covering part, and ensuring that the loose piece (3) can be arranged in the cavity matched with the shallow cavity in the large aluminum alloy skin covering part on the die in the step one;
step three: blanking raw materials: cutting and blanking by using a plate cutting machine according to the calculated size of the flat plate, and efficiently and uniformly spraying graphite emulsion on the upper surface of the plate by connecting an air compressor and an air pressure regulating device with a spray can containing lubricating liquid;
step four: early preparation: fixing the upper die (1) in the first step on an upper platform of a press machine, ensuring the upward die attaching direction of a plate (2), fixing a lower die (4) provided with a movable block (3) on a lower platform of the press machine by using a pressing plate, heating to a target temperature, then placing the plate, preserving heat to fully heat the plate, and after softening, applying a mold closing force by using a hydraulic cylinder for multiple times, preserving pressure and enabling a sealing edge material to fully flow into a sealing edge groove (7);
step five: gas forming: filling gas into the die fixed on the upper platform of the press in the fourth step, so that the plate (2) arranged in the die in the fourth step deforms under the action of air pressure and is gradually attached to the cavity structure of the upper die (1);
step six: taking out the parts: in the final die-attaching and pressure-maintaining stage, an air inlet through hole (5) in an upper die (1) is connected with a vacuum pump, the pump is opened in the workpiece taking stage to discharge gas in a cavity, the pump is closed after a press opens the die, and a crowbar applies force through a jaw (11) to complete part demoulding;
step seven: product treatment: and after the temperature is reduced to room temperature, roughly cutting and finely cutting parts, and respectively carrying out chemical and physical surface treatment to obtain one of the shallow cavity large curved surface aluminum alloy skin parts with high shape precision, wherein the symmetrical parts only need to be inverted by a mould, and other processes are not changed, so that the effect of one mould for two parts can be achieved.
2. A method of forming two-piece, one-die molding for symmetrical features of each other, as claimed in claim 1, wherein: the depth of the shallow cavity arranged in the large-medium aluminum alloy skin covering piece in the first step is less than 200mm.
3. A method for forming two symmetrical features in a single mold, as defined in claim 2, wherein: in the mould structure in step one, go up mould (1) and bed die (4) and all need set up air inlet through hole (5), banding platform (6) plane is parallel with the press platform, and go up and all need design square banding groove (7) on mould (1) and bed die (4), two banding grooves (7) must the dislocation set, the horizontal distance of dislocation must be more than 8mm, a keep silent (11) of every 400mm design on banding platform (6) in last mould (1) and the banding platform (6) in bed die (4).
4. A method for forming two symmetrical features in a single mold, as defined in claim 3, wherein: and the loose piece (3) in the second step is a rough-machined volume filler or a fine-machined cavity entity.
5. A method of forming two-piece, one-die molding for symmetrical features of each other, as claimed in claim 4, wherein: and (3) reserving plate material allowance of 40-60 mm on the plate material (2) in the third step, and standing for 12 minutes after the graphite emulsion is completely sprayed on the upper surface to ensure that the graphite emulsion is stably attached.
6. A method for forming two symmetrical features in a single mold, as claimed in claim 5, wherein: in the fourth step, the temperature rising speed of the press is 2 ℃ per minute on average, the forming temperature is 460-520 ℃, the temperature of the plate (2) is kept for 15 minutes after the plate is placed in the press, and the edge sealing hydraulic pressure of the hydraulic cylinder of the press is 15-22 MPa.
7. A method of forming two-piece, one-die molding for symmetrical features of each other as claimed in claim 6, wherein: in the fifth step, argon or nitrogen is filled into the die fixed on the upper platform of the press in the fourth step, and the temperature of the filled gas is 30-40 ℃.
8. A method of forming two-piece, one-die molding for symmetrical features of each other, as claimed in claim 1, wherein: and in the fifth step, the working process of filling gas into the die fixed on the press in the fourth step comprises the steps of filling gas into the gas inlet through hole (5) in the upper die (1) for preforming, and then filling gas into the gas inlet through hole (5) in the lower die (4) for final forming.
9. A method of forming two-piece, one-die molding for symmetrical features of each other, as claimed in claim 1, wherein: and in the fifth step, the working process of filling gas into the die fixed in the press in the fourth step is to directly fill gas into the gas inlet through hole (5) in the lower die (4) for final forming.
10. A method of forming two-piece, one-die molding for symmetrical features of each other as claimed in claim 8, wherein: and in the step five, the process is controlled according to the curve of the numerical simulation result during gas forming, the reverse expansion pressure is less than 1.5MPa, the final expansion pressure is less than 3MPa, and the pressure maintaining time after the maximum pressure is reached is more than 30 minutes.
11. A method of forming two-piece, one-die molding for symmetrical features of each other as claimed in claim 9, wherein: and in the step five, the process is controlled according to the curve of the numerical simulation result during gas forming, the final expansion pressure is less than 3MPa, and the pressure maintaining time after the maximum pressure is reached is more than 30 minutes.
12. A method of forming two-piece, one-die molding for symmetrical features of each other, as claimed in claim 1, wherein: and in the sixth step, after pressure maintaining is finished, before pressure releasing, the air inlet through hole (5) in the upper die (1) is connected with a vacuum pump, when the vacuum degree is below 10000Pa, suction is maintained, the vacuum pump is closed after gas is exhausted, and part demoulding is realized under the dual effects of the self gravity of the part and the prying force of the jaw (11).
13. A method of forming two-piece, one-die molding for symmetrical features of each other, as claimed in claim 1, wherein: and seventhly, after the part is taken out, the molded surface of the part is accurately cut according to the three-dimensional digital-analog drawing, surface oxidation substances are removed through acid washing and alkali washing, and after surface dirt is removed through a flat diaphragm machine, one of the shallow-cavity large-scale curved-surface aluminum alloy skin parts with high shape precision is obtained.
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