Reconfigurable Multipoint Forming Using Waffle-Type Elastic Cushion and Variable Loading Profile

There is an increasing demand for flexible, relatively inexpensive manufacturing techniques that can accommodate frequent changes to part design and production technologies, especially when limited batch sizes are required. Reconfigurable multi-point forming (MPF) is an advanced manufacturing technique which uses a reconfigurable die consisting of a set of moveable pins to shape sheet metal parts easily. This study investigates the use of a novel variable thickness waffle-type elastic cushion and a variable punch-loading profile to either eliminate or minimise defects associated with MPF, namely wrinkling, thickness variation, shape deviation, and dimpling. Finite element modelling (FEM), analysis of variance (ANOVA), and the response surface methodology (RSM) were used to investigate the effect of process parameters pertaining to the cushion dimensions and type of loading profile on the aforementioned defects. The results of this study indicate that the most significant process parameters were maximum cushion thickness, cushion cut-out base radius, and cushion cut-out profile radius. The type of loading profile was found to be insignificant in all responses, but further investigation is required as the rate, and the thermal effects were not considered in the material modelling. Optimal process parameters were found to be a maximum cushion thickness of 3.01 mm, cushion cut-out base radius of 2.37 mm, cushion cut-out profile radius of 10 mm, and a “linear” loading profile. This yielded 0.50 mm, 0.00515 mm, 0.425 mm for peak shape deviation, thickness variation, and wrinkling, respectively.

Prediction of Process Parameters That Affecting on Surface Roughness in Multi-Point Forming Process Using ANOVA Algorithm

Multipoint forming process is an engineering concept which means that the working surface of the punch and die is produced as hemispherical ends of individual active elements (called pins), where each pin can be independently, vertically displaced using a geometrically reconfigurable die. Several different products can be made without changing tools saved precious production time. Also, the manufacturing of very expensive rigid dies is reduced, and a lot of expenses are saved. But the most important aspects of using such types of equipment are the flexibility of the tooling. This paper presents an experimental investigation of the effect of three main parameters which are blank holder, rubber thickness and forming speed that affect the surface integrity for brass (Cu Zn 65-35) with 0.71 mm thickness. This paper focuses on the development of prediction models for estimation of the product quality. Using Analysis of Variance (ANOVA), surface roughness has been modeled. In the development of this predictive model, blank holder, rubber thickness and forming speed have been considered as model parameters. The mean surface roughness (Ra) is used as response parameter to predict the surface roughness of multipoint forming parts. The data required has been generated, compared and evaluated to the proposed models obtained from experiments. Taguchi algorithm was used to predict the forming parameters (blank holder, rubber thickness and forming speed) on product roughness in forming process of Brass (Cu Zn 65-35) based on orthogonal array of L9 and finally ANOVA was used to find the optimum parameters that have effect on the product quality.

NUMERICAL INVESTIGATION OF THE INFLUENCE OF PUNCH TIP RADIUS AND INTERPOLATOR TYPE IN MULTI-POINT FORMING

Multi-point forming (MPF) is a new flexible forming technology in which the fixed shape of conventional dies is replaced by a pair of opposed matrices of movable punch elements called "punch group".By using multi-point die a variety of three dimensional sheet parts of different shapes can be produced. However due to the discrete contacts between the work piece and punches the dimple defects occurred. In this paper, B-spline technique was used to represent the profile of the final product shape by adjusting the punch height of reconfigurable die. Finite element code (ANSYS 11) was used to simulate the MPF process and to investigate the influence of punch tip radius the interpolator type on the stress distribution, thickness variation and dimpling defect .The simulation results show that the large tip radius and (4mm) rubber interpolator have a great effect in reducing the stress concentration, thickness variation and also prevent the dimpling defect.

PREDICTION AND ENHANCEMENT OF THICKNESS REDUCTION IN MULTI-POINT FORMING PROCESS USING ANOVA ALGORITHM

Multipoint forming is an engineering concept which means that the working surface of the dieand/or punch is made up of hemispherical ends of individual active elements (called pins), whereeach pin can be independently, vertically displaced using a geometrically reconfigurable die,precious production time is saved because several different products can be made withoutchanging tools. The aim of this work is to present the effect of many parameters (blank Holdertypes, rubber thickness and forming speed) on the reduction of thickness for brass with 0.71 mmthickness. This research is concentrate on the development of predictive models to estimate theminimum deviation in thickness using analysis of variance (ANOVA), minimum thicknessdeviation has been modeled. In the development of this predictive model, blank holder, rubberthickness and forming speed have been considered as model parameters. Arithmetic theminimum thickness deviation used as response parameter to assess the thickness reduction ofMultipoint forming parts. The data required has been generated, compared and evaluated to theproposed models that obtained from experiments. Taguchi algorithm is used to predict theeffect of forming parameters on thickness reduction in forming process of Brass (65-35) basedon orthogonal array of L9. The analysis of variance was used to find the best factors that effecton the thickness deviation, The result of this research is the contribution of blank holder types,rubber thickness and forming speed with respect to minimum thickness deviation is (69.195,18.1 and 12.733) % respectively.

Research Progress and Application of Multi-Point Forming

The research progress was introduced about multi-point forming press. It include forming process, reconfigurable die and finite element method. The forming method provided the techonology for development of the aviation industry and automotive industry. The application prospect and techonology dominance were instructed by illuminating body frame of coach.