The numeric imitate of spring back of punch of board makings much pace studies

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Summary: Spring back is process of figuration of board makings punch in a kind common but very scabrous phenomenon. Studied board makings curves the principle that spring back uninstalls in be out of shape above all, go up in order to depend on dimension sidewall stalking or branch next inside board for exemple, use trends and the method that static algorithm combines, on the base that considers spring back of makings of every working procedure board, undertake the numeric imitate of spring back of much pace punch to its, undertake comparative to imitate result and experimental result finally, this imitate method raises test and verify the effectiveness of precision of spring back computation, be craft of figuration of board makings punch make provide scientific basis. Keyword: Spring back; Much pace punch; Numeric imitate 1 preface normally, a whole punch process should be delayed through pulling, the ability of much pace working procedure such as plastic, long edge, punching, flange is finished. In this one process, spring back is craft of board makings figuration the crucial factor that the consideration wants in making, the final figure of the spare parts depends on the spring back quantity after figuration, after spring back quantity allows tolerance more than, make figuration defect, affect the geometrical precision of the spare parts. Because high strenth is thin,use of armor plate and aluminium alloy plank in great quantities in last few years especially, spring back issue is more outstanding. Current, of board makings spring back forecast accurately and how to reduce the spring back quantity, heat problem in reducing leftover stress to make simulation of board makings figuration. From NUMISHEET ' 93 (figuration of the 2nd board makings is three-dimensional and numeric imitate international conference) begin, every conference concerns the standard examination questions that forecasts at spring back (BENCHMARK) , in NUMISHEET ' 99 go up, technically one is forecasted about spring back with special topic of conference of pilot of spring back error, its Chinese chapter achieves 10, occupy the 11 ﹪ of full meeting article about; And in NUMISHEET ' 2002 go up, be forecasted about spring back and pilot conference is monographic those who amount to 20, occupy the 21 ﹪ above of full meeting paper. Should be controlled in actual production and compensate spring back, raising the precision that spring back forecasts is crucial. When normally we are undertaking the spring back of punch of board makings much pace forecast, oversight board makings after every working procedure uninstall spring back, in the computation that did not consider its spring back below one working procedure, however the final figure of board makings is his whole be out of shape historical accumulation effect, its are out of shape pair of leftover stress such as the history and spring back computation have certain effect, so because of oversight the spring back after every working procedure and the accumulation of generation the spring back with ultimate effect of error certainly will forecasts precision. When the article is undertaking imitate of numerical value of punch of board makings much pace, go up with depending on dimension sidewall stalking or branch inside board for exemple, the method that uses trends and static algorithm to be united in wedlock comes imitate its are much pace punch process, the spring back of before one working procedure computation serves as the input of below one working procedure as a result, the contrast that passes imitate result and experimental result comes the validity of this numeric imitate process reachs test and verify effectiveness. The numeric imitate of spring back of punch of much pace of 2 board makings studies 2.

When 1 board makings uninstalls the principle of spring back to study board makings produces a kind of any plasticity to be out of shape below outer load action, its are out of shape is be out of shape by plasticity and flexibility is out of shape two parts are comprised. After be being dropped when discharge of the load outside making what go up with board makings, plasticity is out of shape the material of the area is saved remains is out of shape and make the spare parts is out of shape. But, because flexibility is out of shape the flexibility of area material restores and plasticity is out of shape area material flexibility is out of shape partial flexibility restores, make its appearance, dimension happens with be out of shape direction changes instead when to load, this kind of phenomenon says for spring back. This is the internal cause of phenomenon of the spring back in production. Spring back phenomenon is purify of the load outside becoming actually hind, board makings produces what flexibility restores and cause, this is the material in uninstalling a process actually is add be out of shape. Uninstalled flexibility restores is a course that seeks in-house stress to be balanced oneself, of generation play form restore meet an emergency to cause appearance of spare parts geometry to produce a change (namely spring back) , when the spare parts achieves in-house stress to be balanced oneself, flexibility restores process end, at this moment odd internal stress is leftover stress namely. Be out of shape with playing plasticity to bend for exemple, bend be out of shape the area is outlying curve pitching moment action, at inside area generation is tangential compress stress, outskirt generation is tangential tensile stress, be out of shape on division section tangential if stress pursues 1 (A) be shown. In the meantime, be out of shape the flexibility in the two areas outside the ﹑ inside the area is out of shape composition arose to be out of shape with plasticity the stretch stress with stress opposite way, see a picture 1 (B) . After uninstalling, bend the generation below pitching moment action bends to be out of shape accordingly in flexibility (namely spring back) and obtain new balance position. And plasticity stress and stretch stress form new stress to distributing condition, obtain the new balance position that in-house stress distributings, see a picture 1 (C) , this stress condition makes curve an appearance to be in new steady state. Graph 1 play plasticity to bend those who uninstall interface of makings of process medium plate is tangential stress 2.

Imitate can assign the spring back numerical value with the numeric complete imitate of spring back of punch of much pace of 2 board makings for two paces: Imitate of process of to load figuration and uninstall imitate of spring back process. Computation of before one pace is foundation of simulative of spring back process, provide the stress, data such as meet an emergency for its, this pace calculative is accurate will affect precision of spring back calculative directly. The process of punch of board makings much pace is the figuration process of a many line working procedure actually, the imitate precision that the imitate result of before one working procedure affects below one working procedure directly. Normally we are when the process of much pace punch that imitate board expects, oversight the spring back that backboard of every working procedure expects, namely oversight board makings changes in the stress after every working procedure, and the precision of spring back computation of board makings is out of shape with its again closely related the history, so the spring back certainly will after every working procedure will affect oversight the imitate precision with much pace final punch. Imitate of numerical value of spring back of much pace punch is mature backboard of every working procedure expects uninstall spring back process, solution is begged to end junior travel spring back to calculate in every working procedure when imitate, regard the input of below one working procedure as result of spring back calculative next, will undertake playing the numeric simulation of working procedure. This imitate process and actual punch process are consistent, abide by from beginning to end " → of to load figuration uninstalls figuration of to load of spring back → " this one process, raised precision of simulative of numerical value of punch of board makings much pace thereby. On 3 Yi Weike sidewall inside board imitate of numerical value of spring back of much pace punch pursues on 2 Yi Weike sidewall inside board will be aimed at Yi Weike sidewall to go up below inside board (if pursue 2) , use Dynaform software regards around as the tool of processing, the method that uses trends and static algorithm to be united in wedlock (use LS-DYNA regards every working procedure as numeric simulative seek solution implement, LS-NIKE3D serves as uninstall spring back calculative to seek solution implement) , punch of much to its pace and process of its spring back undertake numeric imitate, be in in section plane A and section plane B (basically be aimed at place I and place II) undertake comparative to imitate result and experimental result. Go up according to dimension sidewall stalking or branch inside board process of much pace punch includes to pull delay, flange of the punching that decorate a border, plastics the punch working procedure of 3 models. Adoption data is ST14O5, ply is 0.

7mm, if data performance data expresses 1 to show. When undertaking numeric imitate to process of much pace punch, after line working procedure ends, every undertake spring back is calculated above all, input the result of spring back below one working procedure to undertake begging solving next, the is out of shape historical information is to pass every pace to beg solution to end have a youthful look to become Dynain file that its medium plate expects will come true to be calculated in each working procedure and spring back between deliver. Go up to depending on dimension sidewall stalking or branch inside board, we divided kind of condition to undertake the numeric imitate of spring back of much pace punch to its: 1) condition one: It is the spring back that considers board makings after every working procedure ends, input result of spring back simulative below one working procedure next; 2) condition 2: Take no account of the spring back of board makings after every working procedure ends, undertake to its after flange ends spring back is calculated merely. The data performance data that expresses 1 ST14O5 pursues 3, 4, 5 it is condition temporarily, join the spring back computation of board makings after every working procedure ends namely, board makings is in pull delay, the punching that decorate a border and plastic flange each the equivalent stress after working procedure and imitate of its spring back distributings graph. Can see from inside the graph, in the spring back imitate after each working procedure, the node of the majority on board makings is in uninstall condition, but the area around partial node appeared the phenomenon of local to load, if pursue 3 (B) medium area A, graph 5 (B) medium area B. Because,this is although spring back is belonged to small be out of shape nonlinear problem, but it is the process that turns to flexibility to uninstall from complex complete stress substantially, this is a very complex process, be out of shape unlike general flexibility computation. Itself of spring back phenomenon is the result that figuration board expects internal stress is released, but because,meet in local district all round the meet an emergency of area unit produces retrorse to load to this area, cause the accretion of stress thereby. To the spring back of intricate work, retrorse to load normally the area with very small radius of curvature of bureau be confined to, if workpiece round horn is in, it is a graph namely 3 (B) medium area A, graph 5 (B) medium area B. Graph 3 condition are pulled temporarily after delaying, reach pull the equivalent stress after delaying spring back to distributing the equivalent stress after after 4 condition repair edge punching temporarily, the graph reachs spring back of the punching that decorate a border distributings pursue, oversight the stress after every working procedure is uninstalled (include local to load) process, direct and advanced the consideration that has issueing a working procedure below the board material status after working procedure ends together. Such imitate process and actual production process are abhorrent, because of the oversight after every working procedure spring back and the error of generation is sure will accumulate last working procedure, affect result of final spring back imitate thereby. Be aimed at these two kinds of different imitate processes, the article parts to be in to section plane A and section plane B (if pursue 2) quantity of final spring back and experimental result undertook comparative. The position with larger amount of the spring back after plastic flange basically is mixed in place I place II (if pursue 2) , the reason spring back quantity these two place and experimental result undertook comparative, basically measure the positional deviation of Y direction and Z direction. Graph 6, graph the spring back quantity of the 7 outline that are section plane A and section plane B respectively and imitate result and experimental result compares a situation. Can see from inside the graph, spring back is joined to calculate after every working procedure (condition one) imitate result and experimental result get very good be identical, mix even in a lot of place imitate results experimental result is main coincide, the oblique plane place of 7b of the flange place in 7c of the 6c that be like a graph, graph, graph. And oversight the spring back after every working procedure (condition 2) imitate result compares position apparently the precision of one is low, with the error with experimental result bigger than appearing look, in 7b of the 6b that be like a graph, graph most the flange place of the lower end, in 7c of graph 6c, graph most go up the flange place of end. Graph the outline of A of the section plane below two kinds of 6 condition and spring back quantity pursue quite of B of the section plane below two kinds of 7 condition outline and spring back quantity are compared through be opposite imitate result and experimental result undertake comparative, see not hard in simulative of numerical value of much pace punch spring back is joined to calculate in the process intermediate, well and truly imitate the process of punch of board makings much pace, the spring back that raised punch of board makings much pace greatly forecasts precision. 4 summary are in among simulative of numerical value of punch of board makings much pace in the process join spring back computation, procedure of relatively traditional imitate of much pace punch, avoided because of oversight every the spring back after working procedure and the stress change imitate that cause the not accurate, issue that affects precision of imitate of final process spring back then, because of this this imitate process board makings is in well and truly imitate the to load figuration in process of much pace punch and the process that uninstall spring back, and board makings is between each working procedure the metabolic circumstance of stress information, raised precision of simulative of spring back of punch of board makings much pace greatly, be craft of board makings figuration constitute the basis that provided science. 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