CN109622682B - Springback compensation method in heating bending process - Google Patents

Springback compensation method in heating bending process Download PDF

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Publication number
CN109622682B
CN109622682B CN201811595842.0A CN201811595842A CN109622682B CN 109622682 B CN109622682 B CN 109622682B CN 201811595842 A CN201811595842 A CN 201811595842A CN 109622682 B CN109622682 B CN 109622682B
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bending
forming
temperature
bending angle
heating
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CN109622682A (en
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段永川
杨柳
姚丹
高安娜
田乐
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Yanshan University
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Yanshan University
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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
    • B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
    • B21D5/006—Bending sheet metal along straight lines, e.g. to form simple curves combined with measuring of bends
    • 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
    • B21D37/16—Heating or cooling
    • 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
    • B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
    • B21D5/06—Bending sheet metal along straight lines, e.g. to form simple curves by drawing procedure making use of dies or forming-rollers, e.g. making profiles

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)

Abstract

The invention discloses a springback compensation method in a heating bending process, which comprises the following steps: selecting two different forming temperatures, and respectively measuring the bending angles after rebounding at the two temperatures; calculating the slope of the rebound bending angle of the material in hot bending forming by using the selected forming temperature and the corresponding rebound bending angle; determining the first formal bending forming temperature according to the slope of the bending angle, and measuring the bending angle after rebounding at the corresponding temperature; and correcting the current forming temperature by using the deviation of the bending angle after the last rebound and the target bending angle until the bending forming times reach the preset forming times. According to the invention, under the condition that the die parameters in the die bending process are not changed, the bending angle after the die bending process rebounds can be compensated by adjusting the temperature applied to the plate, so that the consistency of the angle of the formed bent part is improved, the time for repairing and testing the die is saved, and the flexibility of forming the plate made of different materials by one set of die is improved.

Description

Springback compensation method in heating bending process
Technical Field
The invention relates to the field of material processing, in particular to a springback compensation method in a heating bending process.
Background
in the bending process of the plate, the outer layer fibers of the plate are under tensile strain, the inner layer fibers are under compressive strain, when external force is unloaded, the inner layer fibers release compressive stress to extend, the outer layer fibers release tensile stress to contract, therefore, after the plate is bent and unloaded, the bending angle is reduced compared with that before the plate is unloaded, and the reduction of the bending angle is bending resilience. The amount of springback of the sheet material is affected by many factors, such as material properties, bend geometry, etc. The high-strength plate is more and more required by meeting the requirements of energy conservation and emission reduction of automobiles, but the bending resilience is larger along with the yield and the strength of the high-strength plate, and for the die bending process, if the plate properties are consistent, the bending part after resilience is close to a target bending part as much as possible by a method of adjusting the shape of a die, but the rolled plate is often different in batches, and the mechanical property difference of the plate can be brought by different winding times and different directions, so that the consistency of the formed result is difficult to ensure by the plate. If the die repairing is unrealistic for each plate, the consistency of parts formed by the die bending process is greatly improved, the die repairing cost of the die is reduced, and the production efficiency is improved by using the heating bending springback compensation method.
Disclosure of Invention
the invention provides a thermal bending springback compensation method, which is used for compensating bending springback caused by the inconsistency of sheet properties.
In order to realize the purpose, the invention is realized according to the following technical scheme:
A springback compensation method in a heating bending process is characterized by comprising the following steps:
step A, selecting two different forming temperatures to perform a heating bending forming experiment for determining a parameter k;
B, calculating the bending angle slope k of the material after rebounding in heating bending;
Step C, determining the temperature of a first formal bending forming experiment and performing a bending experiment;
And D, correcting the current forming temperature by using the parameter k and the bending angle deviation.
In the above technical solution, the specific method of the heating bending forming experiment in step a is as follows: and heating the outer convex side of the bending piece to be formed by using the induction coil, stopping heating when the heating reaches a selected temperature, quickly pressing the male die, recording the bending angle after rebounding after the bending is finished, forming for 3 times at the temperature, and averaging the bending angle after rebounding for three times.
in the above technical solution, the specific method for calculating the slope k of the bending angle after springback in step B is as follows:Wherein, Tc1And Tc2For the two different forming temperatures to be selected,Are respectively Tc1，Tc2Three times heating bending forming at temperatureaverage value of bending angle after rebound of experiment.
In the above technical solution, the specific method for determining the first formal bending test temperature T1 in step C includes: t is1＝T0+(αt-α0) K, wherein T0＝Tc1，αtIs the target bend angle.
In the above technical solution, the specific method for correcting the current forming temperature by using the parameter k and the bending angle deviation in the step D comprises: by using the bending angle after the last rebound and the target bending angle alphatCorrecting the current forming temperature TiThe correction formula is as follows: t isi＝Ti-1+(αt-αi-1) And k, finishing the experiment until the bending forming times reach the preset forming times and the correction is finished.
Compared with the prior art, the invention has the following advantages:
According to the invention, under the condition that the die parameters in the die bending process are not changed, the bending angle after the die bending process rebounds can be compensated by adjusting the temperature applied to the plate, so that the consistency of the angle of the formed bent part is improved, the time for repairing and testing the die is saved, and the flexibility of forming the plate made of different materials by one set of die is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a flow chart of a method of compensating for flexure springback of the present invention;
FIG. 2 is a process of the bending spring back compensation method of the present invention;
FIG. 3 is a flow chart of the method for compensating for bending spring back according to the present invention using a deviation to correct the forming temperature;
FIG. 4 is a schematic view of an induction coil heating plate;
In the figure: 1. the device comprises a male die, 2, a plate, 3, an induction coil, 4 and a female die.
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.
FIG. 1 is a flow chart of a method of compensating for bending spring back according to the present invention, as shown in FIG. 1, the method comprising:
Step A, selecting two different forming temperatures to perform a heating bending experiment for determining a parameter k;
B, calculating the bending angle slope k of the material after rebounding in heating bending;
Step C, determining the temperature of a first formal bending forming experiment;
D, correcting the current forming temperature by using the parameter k and the bending angle deviation;
fig. 3 is a flow chart of using deviation to correct forming temperature in the bending springback compensation method of the present invention, as shown in fig. 3, the correction process is:
(1) Presetting a forming member number n according to Tc1And Tc2Bending forming experiment under temperature obtains parameter k, T0,α0Where k is the angle slope of the bend after rebound, T0＝Tc1，α0Is at Tc1The bending angle after springback measured by a bending forming experiment at temperature;
(2) Performing a first formal bending forming experiment to determine a first formal forming temperature T1＝T0+(αt-α0) K, wherein, αtA target bending angle; measuring the corresponding bending angle alpha after springback1；
(3) Performing a second formal bending forming experiment, and measuring the bending angle alpha after springback2second forming temperature T2Angle of bending alpha after first rebound1Angle of bending with respect to targettThe formula of the deviation correction is as follows:
Ti＝Ti-1+(αt-αi-1)/k
Wherein, i is the current forming times, and i is 1,2, 3.
(4) And (5) repeating the step (3) until the bending forming times reach the preset forming times, namely i is equal to n, and ending the experiment.
Each of the above steps is explained below with reference to specific examples.
According to the invention, under the condition that the die parameters in the die bending process are not changed, the bending angle after the die bending process rebounds can be compensated by adjusting the temperature applied to the plate, and the bending tester is taken as an example for forming a steel plate. The specification of the steel plate is as follows: the steel plate is 22MnB5, the thickness H of the steel plate is 1mm, the width B of the steel plate is 50mm, and the length L of the steel plate is 150 mm.
Step A: selected bend forming temperature Tc1＝74℃，Tc2Heating the outer convex side of the steel plate by using an induction coil at 438 ℃, and when the temperature reaches Tc1Stopping heating when the temperature is 74 ℃, rapidly pressing down the male die, wherein the pressing stroke is 85mm, collecting and measuring the bending angle of the plate by using a three-coordinate measuring instrument after rebounding, forming for three times at the temperature, respectively measuring the bending angles after rebounding to be 104.1 degrees, 104.2 degrees and 104.1 degrees, and then averagingIs 104.13 degrees.
for the same reason, when the temperature reaches Tc2bending was carried out while stopping heating at 438 ℃ and the bending angles after springback were measured to be 98.1 °, 98.2 °, 98.2 °, respectively, and the average values were98.17 °;
B, calculating the bending angle slope k after springback according to the parameters obtained in the step A:
And C: now, a first bending test is performed, and assuming that the target bending angle to be formed is 101 °, the first bending test temperature T is set1＝T0+(αt-α0) Heating the outer convex side of the steel plate by using an induction coil at 264.75 ℃, and when the temperature reaches T1Stopping heating when the temperature is 264.75 ℃, rapidly pressing down the male die, keeping the pressing stroke not to be 85mm, and measuring the bending angle alpha after springback by a measuring tool1101.8 degrees, and has deviation from the target bending angle;
Step D: now, a second bending test is performed, in which the second forming temperature is corrected by the deviation between the bend angle after the first springback and the target bend angle, and if i is 2, the temperature used for the second forming is T2＝T1+(αt-α1)/k＝313.53℃。
The third or more bending test procedure was repeated as described above. If the material performance fluctuates and the size changes are caused by the temperature rise of the die and the like, the springback compensation can be eliminated by the method.
the foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims (5)

1. A springback compensation method in a heating bending process is characterized by comprising the following steps:
Step A, selecting two different forming temperatures Tc1and Tc2Performing a heating bending forming experiment to obtain a corresponding bending angle after springbackand
b, calculating the slope k of the bending angle after rebounding of the material in the heating bending process according to the ratio of the difference value of the bending angle after rebounding to the temperature difference value, namely the variation of the bending angle after rebounding at each temperature;
Step C, bending angle alpha after target reboundtand Tc1Spring back bend angle at temperatureDetermining the target post-rebound bending angle alphatDesired bending temperature T1；
step D, utilizing the bending angle after springback obtained by the experiment and the target bending angle after springback alphatThe required forming temperature is continuously corrected until the number of bending forming times reaches the preset number of forming pieces.
2. the method for compensating for springback in a heating bending process according to claim 1, wherein: the specific method of the heating bending forming experiment in the step A comprises the following steps: and heating the outer convex side of the bending piece to be formed by using the induction coil, stopping heating when the heating reaches a selected temperature, quickly pressing the male die, recording the bending angle after rebounding after the bending is finished, forming for 3 times at the temperature, and averaging the bending angle after rebounding for three times.
3. The method for compensating for springback in a heating bending process according to claim 2, wherein: the specific method for calculating the bending angle slope k after springback in the step B comprises the following steps:Wherein, Tc1and Tc2For the two different forming temperatures to be selected,are respectively Tc1，Tc2And average value of bending angles after springback of three times of heating bending forming experiments at the temperature.
4. the method for compensating for springback in a heating bending process according to claim 3, wherein: determining the target post-rebound bend angle α as set forth in step Ctdesired bending temperature T1The specific method comprises the following steps: t is1＝T0+(αt-α0) K, wherein T0＝Tc1，αtis the target bend angle.
5. The method for compensating for springback in a heating bending process according to claim 4, wherein: step D, obtaining the rebound post-bending angle and the target rebound post-bending angle alpha by using the experimenttThe specific method for continuously correcting the required forming temperature comprises the following steps: by using the bending angle after the last rebound and the target bending angle alphatCorrecting the current forming temperature Tithe correction formula is as follows: t isi＝Ti-1+(αt-αi-1) And k, finishing the experiment until the bending forming times reach the preset forming times and the correction is finished.
CN201811595842.0A 2018-12-26 2018-12-26 Springback compensation method in heating bending process Active CN109622682B (en)

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CN113560826B (en) * 2021-08-13 2022-09-09 燕山大学 Welded pipe forming method for comprehensively controlling springback through warm forming and light overbending
CN114505389B (en) * 2022-02-17 2023-12-22 北京理工大学重庆创新中心 High-strength steel hot stamping forming optimization method utilizing mechanism to compensate ambient temperature

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JP3849189B2 (en) * 1996-11-13 2006-11-22 石川島播磨重工業株式会社 Bending method of metal plate by linear heating
CN102500672A (en) * 2011-10-25 2012-06-20 山东硕力机械制造有限公司 Method and device for forming plates through gradual approximation bending
US9921572B2 (en) * 2013-11-12 2018-03-20 Embraer S.A. Springback compensation in formed sheet metal parts
CN104307939A (en) * 2014-09-25 2015-01-28 北京航星机器制造有限公司 Springback compensation method of thin-wall stamped part with large relative bending radius
CN105868428A (en) * 2015-01-20 2016-08-17 迪艾工程技术软件（上海）有限公司 Springback compensation method of stamped part
CN106077170B (en) * 2016-07-14 2017-11-24 燕山大学 A kind of bending curvature springback compensation control method
CN106295055A (en) * 2016-08-22 2017-01-04 南京埃斯顿自动化股份有限公司 A kind of bender bending method that upper mold depth is carried out bending springback compensation

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