CN110314971B - Pressure forming resilience self-adaptive control method for plate viscous medium - Google Patents

Pressure forming resilience self-adaptive control method for plate viscous medium Download PDF

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Publication number
CN110314971B
CN110314971B CN201910718907.4A CN201910718907A CN110314971B CN 110314971 B CN110314971 B CN 110314971B CN 201910718907 A CN201910718907 A CN 201910718907A CN 110314971 B CN110314971 B CN 110314971B
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medium
pressure
plunger
bin
viscous medium
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CN110314971A (en
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王忠金
冯业坤
杨继平
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Harbin Institute of Technology
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Harbin Institute of Technology
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21DWORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D26/00Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02Shaping 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
    • B21D26/021Deforming sheet bodies
    • B21D26/027Means for controlling fluid parameters, e.g. pressure or temperature

Abstract

The invention relates to a pressure forming resilience self-adaptive control method for a plate viscous medium, which comprises the following stepsThe method comprises the following steps: i: fixing the medium bin, installing a plunger inside the medium bin, and injecting a viscous medium into the medium bin; II: placing the plate blank on the top of the medium bin, and then mounting and fixing the female die on the plate blank to clamp the plate blank between the medium bin and the female die; III: pushing a plunger in a media cartridge at a velocity V1Moving upwards to enable the plate blank to be gradually attached to the cavity of the female die, wherein the pressure in the medium bin is P; IV: the plunger is caused to rotate at a speed V2Downward movement to reduce the pressure in the medium bin to P1And simultaneously stopping the downward movement of the plunger to keep the pressure in the medium bin constant at P1Duration t; v: pressure P1After a constant duration t, the plunger is again at a speed V2Moving downwards until the viscous medium is completely unloaded; the invention has the advantages that the formed piece is repeatedly attached to the die in the unloading process and the residual stress is gradually released, so that the springback is controlled.

Description

Pressure forming resilience self-adaptive control method for plate viscous medium
Technical Field
The invention relates to the technical field of plate forming, in particular to a pressure forming resilience self-adaptive control method for a plate viscous medium.
Background
The springback is generated after the plate is stamped, formed and unloaded, the nature of the springback is that the distribution of internal stress is uneven after the plate is formed, and the stress field caused by the release of residual stress in the formed part is in the process of reestablishing balance in the unloading process, so the size of the springback depends on the internal stress state of the formed part before the springback and the geometric shape of the formed part. At present, springback is a phenomenon widely existing in sheet plastic forming, seriously influences the size and shape precision of a stamping part, and is a problem to be solved urgently in the industry and academia. The existing control means for springback control the springback to a certain extent by optimizing various process parameters such as blank holder force, lubrication conditions, slab shape and the like on one hand, and compensate the springback by optimizing the die profile on the other hand, but the existing methods have the defects of long time consumption, high cost, limited size precision improvement range and incapability of fundamentally controlling the springback, and a method for inhibiting the springback through pressure control of forming in the forming process must be explored.
Disclosure of Invention
The invention aims to solve the technical problem of providing a pressure forming resilience self-adaptive control method for a plate material by using viscous medium, aiming at the defects in the prior art.
In order to solve the technical problem, the invention provides a pressure forming resilience self-adaptive control method for a plate material by using viscous medium, which comprises the following steps of:
i: fixing the medium bin, installing a plunger inside the medium bin, and injecting a viscous medium into the medium bin;
II: placing the plate blank on the top of the medium bin, and then mounting different types of female dies on the plate blank and fixing the female dies to clamp the plate blank between the medium bin and the female dies;
III: pushing a plunger in a media cartridge at a velocity V1Moving upwards to enable the plate blank to be gradually attached to the cavity of the female die under the pressure action of the viscous medium, wherein the pressure in the medium bin is P;
IV: the plunger is caused to rotate at a speed V2Downward movement to reduce the pressure in the medium bin to P1And simultaneously stopping the downward movement of the plunger to keep the pressure in the medium bin constant at P1Duration t;
v: pressure P in the media hopper1After a constant duration t, the plunger is again brought at a speed V2And moving downwards until the viscous medium is completely unloaded, and the pressure in the medium bin is reduced to 0.
As a further illustration of the invention, it is preferred that the media cartridge pressure P1P- Δ P, wherein 0<ΔP<P,P>40MPa。
As a further illustration of the invention, it is preferred that the magnitude of Δ P is a function ofIs increased and decreased withIs increased, where σ issThe yield strength of the plate blank, and E the modulus of elasticity of the plate blank.
As a further illustration of the invention, it is preferred that theIn the range of 1.02X 10-3~1.60×10-3When the pressure is higher than the set value, the delta P is 21-30 MPa;
the above-mentionedIn the range of 1.61X 10-3~2.20×10-3When the pressure is higher than the set value, the delta P is 11-20 MPa;
the above-mentionedIn the range of 2.21X 10-3~3.00×10-3When the pressure is within the range, the delta P is within the range of 5 to 10 MPa.
As a further description of the present invention, preferably, the value of the constant duration t ranges from 5s to 10 s.
As a further illustration of the invention, it is preferred that the velocity V of the upward movement of the plunger is1The value range of (A) is 0.1 mm/s-0.8 mm/s.
As a further illustration of the invention, it is preferred that the velocity V of the downward movement of the plunger is2The value range of (A) is 0.005 mm/s-0.1 mm/s.
As a further explanation of the present invention, it is preferable that the strain rate sensitivity index of the viscous medium is in a range of 0.1 to 0.9.
The implementation of the invention has the following beneficial effects:
1. the method utilizes the strain rate sensitivity of the viscous medium, the pressure of the viscous medium can be self-adapted to the shape change of the plate, and the formed part is repeatedly attached to the die and gradually releases the residual stress in the unloading process by controlling the unloading mode of the viscous medium in the unloading process in the pressure forming of the viscous medium, so that the internal stress gradient of the formed part in the final die attaching process is reduced, and the aim of controlling resilience is fulfilled;
2. according to the invention, the mould parameters are not required to be changed, and the springback is controlled by unloading and controlling the pressure in the medium bin during unloading, so that the time for repairing and testing the mould is saved.
Drawings
FIG. 1 is a schematic structural view of a viscous medium bulging die of the present invention;
FIG. 2 is a schematic diagram of the viscous medium bulging loading end plate blank in a die-attached state according to the present invention;
FIG. 3 is a schematic representation of the invention in pre-rebound and post-rebound conditions;
FIG. 4 is a schematic diagram of the recoating of the slab after springback under the pressure of the viscous medium according to the present invention;
FIG. 5 is a schematic representation of the invention before and after a second rebound;
FIG. 6 is a schematic representation of the present invention in a pre-ith rebound and post-ith rebound condition;
FIG. 7 is a schematic representation of the present invention before and after the nth rebound;
FIG. 8 is a schematic view of the invention in a molded state after completion of forming and complete unloading of the slab;
FIG. 9 is a schematic view of a viscous medium pressure forming die for the stepped member of the present invention;
FIG. 10 is a schematic structural view of a viscous medium pressure forming die for a variable diameter member according to the present invention.
Description of reference numerals:
1. a female die; 2. a sheet blank; 3. a media hopper; 4. a viscous medium; 5. and a plunger.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
A self-adaptive control method for pressure forming resilience of a plate by viscous medium relates to a pressure forming device, which combines the figure 1, the figure 9 and the figure 10, the device comprises a female die 1, a medium bin 3, viscous medium 4 and a plunger 5, a plate blank 2 is required to be processedThe formed sheet material has an elastic modulus E and a yield strength sigmas(ii) a The plate blank 2 is placed on a medium bin 3, a viscous medium 4 is filled in the medium bin 3, the strain rate sensitive index of the viscous medium 4 is m, the non-uniform pressure generated by the viscous medium 4 on the plate blank 2 is related to the value of m, and the viscous medium 4 with different values of m is selected according to different materials of the plate blank 2; the value range of the strain rate sensitivity index m is 0.1-0.9; a plunger 5 is slidably connected in the medium chamber 3 below the viscous medium 4, the plunger 5 moves up to bring the viscous medium 4 into contact with the sheet blank 2; the female die 1 is a die with cavities of various shapes.
With reference to fig. 1, 9 and 10, the adaptive control method for pressure forming resilience of sheet material based on the above device comprises the following steps:
i: fixing the medium bin 3, and injecting a viscous medium 4 into the medium bin 3;
II: placing the plate blank 2 on the top of the medium bin 3, and then installing and fixing the female die 1 on the plate blank 2 to enable the plate blank 2 to be clamped between the medium bin 3 and the female die 1;
III: pushing the plunger 5 in the media cartridge 3 at a velocity V1Upward movement, velocity V1The value range of (A) is 0.1 mm/s-0.8 mm/s; the plate blank 2 is gradually attached to the cavity of the female die 1 under the pressure action of the viscous medium 4, and the pressure in the medium bin 3 is P which is more than 40 MPa;
IV: the plunger 5 is caused to rotate at a speed V2Downward movement, V2The value range of (A) is 0.005 mm/s-0.1 mm/s; the pressure in the medium bin 3 is reduced to P1At the same time, the plunger 5 stops moving downwards, so that the pressure in the medium bin 3 is kept constant at P1Duration t;
v: pressure P in the media compartment 31After a constant duration t, the plunger 5 is again brought at a speed V2Moving downwards as shown in fig. 8 until the viscous medium 4 is completely unloaded, the pressure in the medium reservoir drops to 0, at which time the springback of the sheet blank 2 is suppressed.
Wherein the pressure P of the medium cabin 31Is equal to P- Δ P, and 0<ΔP<P, the magnitude and yield strength of the delta P are sigmasIs related to the ratio of the modulus of elasticity E, i.e.The larger the pressure difference is, the larger the rebound tendency of the plate blank 2 is, and in order to enable the viscous medium pressure to offset the rebound, the smaller the pressure reduction in the medium bin 3 needs to be, and the smaller the delta P is; on the contrary, the present invention is not limited to the above-described embodiments,the smaller the springback of the slab 2, the larger the Δ P.
The slab blank 2 has certain elasticity, the slab blank 2 rebounds when the plunger 5 unloads, the rebound quantity of the slab blank 2 is d, and the magnitude of the rebound quantity d is related to the position of the slab blank 2 in the cavity of the female die 1, for example, d in fig. 31~d9(ii) a The elastic deformation causes the viscous medium 4 in the area near the plate blank 2 to generate compression deformation, the amount of compression deformation D of the viscous medium 4 is set as D, and the magnitude of the compression deformation D is related to the contact position of the plate blank 2, as shown in D in figure 31~D9(ii) a The viscous medium 4 is strainedThe magnitude of the strain is related to the position of contact of the sheet 2, corresponding to d1~d9And D1~D9Strain of the corresponding position is ε1~ε9And strain rate sensitivity of the viscous medium 4Causing the viscous medium 4 to develop a non-uniform stress field, which is dependent on the location of contact of the slab 2, corresponding to d1~d9And D1~D9Stress at corresponding position is σ1~σ9
As shown in fig. 4, the plate blank 2 rebounds, the viscous medium 4 generates a pressure P opposite to the rebounding direction and unevenly distributed to the plate blank 2 (P1< P2< P3< P4< P5> P6> P7> P8> P9), the rebounded plate blank 2 is attached to the die again under the action of the pressure P, and the internal stress gradient of the plate blank 2 is reduced; as shown in fig. 5, if the internal stress gradient of the slab 2 re-molded is still large, a second springback occurs, but the second springback amount is smaller than the first springback amount, and the slab 2 is molded for a third time according to the above process and the internal stress gradient of the slab 2 is further reduced; as shown in fig. 6, the plate blank 2 is rebounded for the ith time, and the plate blank 2 is attached to the die for the (i + 1) th time according to the above process and further reduces the internal stress gradient of the plate blank 2, as shown in fig. 7, and the process is repeated in this way until the internal stress gradient of the plate blank 2 after the nth rebound is small enough to cause no rebound, and the viscous medium 4 is not rebounded after being unloaded.
Aiming at the method, the female die 1 with three different cavities and three different plate blanks 2 are selected for testing, and the specific results are as follows:
the first embodiment is as follows: in the female die 1 in a regular spherical shape,
1. the material of the plate blank 2 is stainless steel 304,is 1.02X 10-3When the temperature of the water is higher than the set temperature,
the size of P is 130 MPa; and when the viscous medium 4 is selected, the strain rate sensitivity index m value is 0.1, the delta P is 25-27 MPa, and V1=0.8mm/s、V2Under the condition of 0.1mm/s, the duration t only needs 5s, and the plate blank 2 can be formed without resilience;
2. the material of the sheet blank 2 is an aluminium alloy AL1060,is 1.81X 10-3When the temperature of the water is higher than the set temperature,
the size of P is 70 MPa; and selecting a viscous medium 4 with a strain rate sensitivity index m value of 0.5, a delta P value of 13-18 MPa and a V value1=0.3mm/s、V2Under the condition of 0.01mm/s, the duration t only needs 7s, and the plate blank 2 can be formed without resilience;
3. the material of the plate blank 2 is a high temperature alloy GH4169,is 2.75X 10-3When the temperature of the water is higher than the set temperature,
the size of P is 150 MPa; and selecting a viscous medium 4 with a strain rate sensitivity index m value of 0.9, a delta P value of 6-8 MPa and a V value1=0.1mm/s、V2Under the condition of 0.007mm/s, the duration t only needs 10s, and the plate blank 2 can be formed without resilience;
example two: the step-shaped female die 1 is selected, the plate blank 2 is made of aluminum alloy AL1060,is 1.81X 10-3When the P is 80 MPa; and when the strain rate sensitive index m value of the selected viscous medium 4 is 0.5, delta P is 11MPa and V is1=0.2mm/s、V2Under the condition of 0.06mm/s, the duration t only needs 8s, and the plate blank 2 can be formed without resilience;
example three: a concave die 1 in the shape of a reducing component is selected, the plate blank 2 is made of high-temperature alloy GH4169,is 2.75X 10-3When the P is 170 MPa; and when the viscous medium 4 is selected, the strain rate sensitivity index m value is 0.9, the delta P is 5MPa, and V1=0.1mm/s、V2The duration t of only 8s, i.e. 0.005mm/s, allows the blank 2 to be formed without springback.
In conclusion, the invention utilizes the strain rate sensitivity of the viscous medium 4, the pressure of the viscous medium 4 can be self-adapted to the shape change of the plate, the unloading mode of the viscous medium 4 in the unloading process is controlled in the pressure forming of the viscous medium 4, so that the formed part is repeatedly attached to the die in the unloading process and the residual stress is gradually released, the internal stress gradient of the formed part in the final die attachment process is reduced, the aim of controlling the rebound can be achieved, the duration time is short, and the processing and forming efficiency is extremely high; meanwhile, the method can be used for different types of plates, and the applicability is very high.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (6)

1. A self-adaptive control method for pressure forming resilience of a plate material by using viscous medium is characterized by comprising the following steps of:
i: fixing the medium bin (3), installing a plunger (5) in the medium bin, and injecting a viscous medium (4) into the medium bin (3);
II: placing the plate blank (2) on the top of the medium bin (3), and then installing different types of female dies (1) on the plate blank (2) and fixing to clamp the plate blank (2) between the medium bin (3) and the female dies (1);
III: pushing a plunger (5) in a media hopper (3) at a velocity V1The plate blank (2) is gradually attached to the cavity of the female die (1) under the pressure action of the viscous medium (4) by moving upwards, and the pressure in the medium bin (3) is P at the moment;
IV: the plunger (5) is caused to rotate at a speed V2Moves downwards to reduce the pressure in the medium bin (3) to P1Simultaneously, the plunger (5) stops moving downwards, so that the pressure in the medium bin (3) is kept constant at P1Duration t, pressure P of the medium chamber (3)1P- Δ P, wherein 0<ΔP<P, P is more than 40 Mpa; the magnitude of the delta P is dependent onIs increased and decreased withIs increased, where σ issThe yield strength of the plate blank (2) and the elastic modulus E of the plate blank (2);
v: pressure P in the medium chamber (3)1After a constant duration t, the plunger (5) is again brought at a speed V2Moves downwards until the viscous medium (4) is completely unloaded, and the pressure in the medium bin (3) is reduced to 0.
2. The adaptive control method for resilience of sheet material formed by pressure of viscous medium according to claim 1,
the above-mentionedIn the range of 1.02X 10-3~1.60×10-3When the pressure is higher than the set value, the delta P is 21-30 MPa;
the above-mentionedIn the range of 1.61X 10-3~2.20×10-3When the pressure is higher than the set value, the delta P is 11-20 MPa;
the above-mentionedIn the range of 2.21X 10-3~3.00×10-3When the pressure is within the range, the delta P is within the range of 5 to 10 MPa.
3. The adaptive control method for the resilience of the pressure forming of the sheet material by the viscous medium according to claim 1, wherein the constant duration t is in a range of 5-10 s.
4. The adaptive control method for pressure forming rebound of sheet material with viscous medium according to claim 1, wherein the velocity V of upward movement of the plunger (5)1The value range of (A) is 0.1 mm/s-0.8 mm/s.
5. The adaptive control method for pressure forming rebound of sheet material with viscous medium according to claim 1, wherein the speed V of the downward movement of the plunger (5)2The value range of (A) is 0.005 mm/s-0.1 mm/s.
6. The adaptive control method for the pressure forming resilience of the plate material as claimed in claim 1, wherein the strain rate sensitivity index of the viscous medium (4) is in the range of 0.1-0.9.
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2119278T3 (en) * 1994-09-29 1998-10-01 Smg Sueddeutsche Maschinenbau PROCEDURE FOR THE FORMATION OF METAL SHEET.
CN101856693A (en) * 2010-05-25 2010-10-13 李义 Moving die compressive stress decomposing and forming method, volume spring and U-shaped bolt composite bending die
CN102248056A (en) * 2011-06-13 2011-11-23 北京航空航天大学 Method for improving sheet forming limit
CN104190777A (en) * 2014-09-26 2014-12-10 中南大学 One-step shaping method for non-aging reinforced aluminum alloy whole wallboard based on autoclave
CN109675998A (en) * 2019-01-23 2019-04-26 哈尔滨工业大学 A kind of viscous pressure forming method of local curvature's mutation sheet cover
CN109675999A (en) * 2019-01-23 2019-04-26 哈尔滨工业大学 A kind of curvature mutation sheet cover viscous pressure forming device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2119278T3 (en) * 1994-09-29 1998-10-01 Smg Sueddeutsche Maschinenbau PROCEDURE FOR THE FORMATION OF METAL SHEET.
CN101856693A (en) * 2010-05-25 2010-10-13 李义 Moving die compressive stress decomposing and forming method, volume spring and U-shaped bolt composite bending die
CN102248056A (en) * 2011-06-13 2011-11-23 北京航空航天大学 Method for improving sheet forming limit
CN104190777A (en) * 2014-09-26 2014-12-10 中南大学 One-step shaping method for non-aging reinforced aluminum alloy whole wallboard based on autoclave
CN109675998A (en) * 2019-01-23 2019-04-26 哈尔滨工业大学 A kind of viscous pressure forming method of local curvature's mutation sheet cover
CN109675999A (en) * 2019-01-23 2019-04-26 哈尔滨工业大学 A kind of curvature mutation sheet cover viscous pressure forming device

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