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In-Process Measurement of Elastic Deformation of a Large Deep-Drawing-Die with Fusion of Experiment and Numerical Analysis Paper: In-Process Measurement of Elastic Deformation of a Large Deep-Drawing-Die with Fusion of Experiment and Numerical Analysis Takahiro Ohashi ∗ , Tomoaki Ando ∗∗ , and Noriyuki Nakaoka ∗∗ ∗ Kokushikan Universi ty 3-4-1 Setagaya, Setagaya-ku, Tokyo 154-8515, Japan E-mail: [email protected] ∗∗ Advanced Simulation Technology of Mechanics (ASTOM) R&D, Co. Ltd. 2-3-13 Minami, Wako-shi, Saitama 351-0104, Japan [Received September 9, 2008; accepted March 24, 2009] We mea sur ed elasti c de forma tio n of a lar ge de ep drawing die in-process and visualized it with a fusion technique of numerical analysis and experiments with multipoin t die support. We found that displace ment by elastically deforming a press machine bolster is up to 0.15 mm when measured directly by displacement sensors. Lower die profile displacement for a half size fender is estimated at 0.25 mm. We numerically analyzed elastic die deformation using multipoint die support to measure and visualize deformation indirectly. We calculated reactive force distribution on the cavity surface and to know it differs with according to distribution patter n of support points, and visualized elastic deformat ion die pattern s. Keywords: die, press-working, deep drawing, in-process measurement, numerical analysis 1. Introduction Phenomena in die-cavity must be known to determine their relation ship to product defects. General numeri cal analysis had been developed to help determine this rela- tionship is useful, but has limitations of ability dealing with the problem. An analysis model could not meet for the actual conditio n because of its uncertainty . For ex- ample, it is not easy for commercial analysis to deal the problem of machine difference and uncertainty of the die- setu p. In-p roce ss measur emen t enab les us to kno w the above phenomena as it is, and we can say that it is a key to solve the actual probl ems which is diffi cult to be solved with using only commercial simulations. Ohanaka et Al. uses x-ray pho tograph y to determi ne the material flow in a casting mold [1]. Yokoi and Murata used pin-arr ays on a touch-s ens ing she et to meas ure inj ec- tion mold cavity surface pressure distribution [2]. Murata also used strain gauges to measure elastic mold deformation to detect fin outbreak [3]. In the rolling process, em- bedded sensors have been used to measure roller surface pressur e distrib ution [4 – 5]. Such the embedd ed sensor is also found in the study of drawing [6]. In the deep drawing for large products such as auto- mobile panels, the die defo rms elas tic all y , but exa ctl y how is unknown . Y oshida et al. analyzed spr ing-bac k in sheet metal forming considering elastic die deformation and foun d dif fere nces in anal yti cal resu lts und er rigid- and elastic-die assumptions [7]. 2. Pr oblems of Mac hin e Dif fer ence in Large Deep Drawing Figure 1 despites typical flow chart for the starting-up of production of a large deep drawing part for an automo- bil e. Tho ugh a produc t is made in multip le dis tri but ed shops in the world to avoid risk, its dies are designed, manu fact ured and exa mined in a cert ain moth er shop gen- erally . They do not work as it is designed ofte n because of their elastic deformation, spring-back of a material and other caus es uncons ide red in des ign. The refore many tri es and corrections are needed in a trial line of the mother shop. After the try-out the dies are shipped to production lines of satellite shops. However the shipped dies do not wor k ofte n in a sat ell ite shop too. It is cons ide red it comes from machine difference. Many causes are expected such as difference of rigidity of machine and floor, motion of slide, reaction of cushion and so on, but have not been reveal ed sufficie ntly . They only make many tries again in the satellite shop and re-correc t the dies. It takes long time and costs additionally. If the starting-up in a satellite shop delays, the other shops must wait until it get ready in international concurrent manufacturing. In-process monitoring of die behavior is considered ef- ficient for determining the cause of and solving problems. We compare the results of in-process monitoring between parent-shop trial lines and satellite shop production lines. We measured elastic deformation of a large deep drawing die in process and visualized with employing fusion of numerical analysis and experiment with the dedicated multipoint die support. Int. J. of Automation T echnology V ol.3 No.4, 2009 457

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