Papers by Keyword: Press Forming

Abstract: This article aims to improve the bonding strength between metal and plastic,the metal substrate is subjected to high-energy shot peening to make the surface self-nitrified, and the orthogonal test scheme was designed based on the process parameters of high energy shot peening and spraying. After molding, the bonding strength of the metal matrix composite was tested by the vertical stretching method. We studied the effect of the cast steel shot diameter, the shot peening pressure, the shot peening time and the plasticizing temperature on the bonding strength of the composite. The combination of process parameters was determined when the bonding strength was optimized, then use the numerical fitting method to predict the combination of process parameters when the bonding strength is the highest, the optimization results are verified by experiments. The results show that the diameter of the cast steel shot is 4.96mm-5.04mm, the shot peening pressure is 0.49MPa-0.51MPa, the shot peening time is 10.9min-11.08min, and the plasticizing temperature is 278.2°C-282°C. The bonding strength of the composite is optimal Keywords: Metal matrix composite, High-energy shot peening, Press forming; Bonding strength, Process optimization

Abstract: The macro-scale and meso/macro-scale simulations for press forming of CFRP sheet using ABAQUS S/W were both implemented to study the influence fiber orientation on the formability of CFRP sheet. The Hashin damage criterion was used to predict the fiber failure in the forming process. The properties of plain woven fiber fabric were obtained from the tensile test and bias extension test. The forming experiments with rectangular punch were carried out to validate the numerical results.

Abstract: A jack-up rig or a self-elevating unit is a type of mobile platform that consists of a buoyant hull fitted with a number of movable legs, capable of raising its hull over the surface of the sea. The buoyant hull enables transportation of the unit and all attached machinery to a desired location. Once on location the hull is raised to the required elevation above the sea surface on its legs supported by the sea bed. The legs of such units may be designed to penetrate the sea bed, may be fitted with enlarged sections or footings, or may be attached to a bottom mat. Generally Jack up rigs are not self-propelled and rely on tugs or heavy lift shipsfor transportation. Formability problems in offshore structure construction where particularly high-strength steels are used for chords and racks. Attainment of mechanical properties is not usually difficult, although procedural trials are advisable. Fatigue cracking is probably the major cause of service failure of jack-up rigs, and the use of high-strength steels, which permits higher static stress limits, can exacerbate this problem. Roll forming process is one of the most widely used processes in the world for forming metals. It can manufacture goods of the uniform cross section throughout the continuous processing. However, process analysis is very difficult because of the inherent complexity. Therefore, it is time-consuming and much money is needed for manufacturing goods. In order to overcome this difficulty, a new computational method based on the rigid-plastic finite element method is developed for the analysis of roll forming process.

Abstract: In this study, new thin corrugated metal gasket will be developed by using simulation experiment. The optimal design and dies design for gasket manufacturing is determined by using computer simulation based on finite element analysis (FEA). In the design stage, the Taguchi method is used to predict optimal design of new thin corrugated metal gasket. The L9 orthogonal array was concerned to design experimental matrix for four factors with three levels. In the manufacturing stage, gasket product is simulated by using ANSYS 14.5 and experimental press forming process by using press hydraulic machine. From the result, the optimal design is the model with R = 3 mm, p = 6 mm, OH = 3 mm and h = 0.2 mm. Based on simulation results and experimental press forming product, it can be concluded that the virtual design from computer simulation results can be used for predicting the real product.

Abstract: Stiffness improvement of stamping die without weight increase 780MPa grade high strength steel sheet was achieved by using Finite Element (FE) simulation combined with topology optimization. In the first step of the procedure, FE simulation of a stamping process was conducted in order to evaluate the contact force on a die surface at the end of stamping. Subsequently, topology optimization was carried out subject to the prescribed weight constraint, in which the stiffest die structure for the given force and displacement boundary conditions was obtained. Maximum displacements during stamping between thus optimized die and the one designed by the experienced engineer were compared. It was found that the optimized die showed less deformation than the other even if the total weights of both dies were almost the same.

Abstract: In press forming, it is most important to prevent wrinkling and cracking. A small clearance between the upper and lower dies is effective for preventing wrinkle generation. However, the small clearance increases sliding resistance between sheet material and dies and causes cracking of sheet material. On the other hand, large deformation of sheet material requires multi-step press working which involves incremental small deformations in order to avoid wrinkling and cracking. But this method requires a number of dies so that it increases cost and development time. In press forming, lubricant to reduce sliding resistance of sheet material is used for preventing wrinkling and cracks. However, the use of lubricant such as chlorofluorocarbon and trichloroethane has been restricted due to environmental concerns. The development of new press working techniques that do not use lubricant is thus desired. Since wrinkling and cracking are mainly caused by friction between sheet material and dies, forming techniques which can decrease the friction without lubricant are needed.

Abstract: Class F fly ash-based geopolymers formed by pressure were prepared, and the preparation factors effecting on properties especially mechanical strength were discussed and optimized. The geopolymer specimens show excellent integrated properties such as mechanical strength, acid-resistance and water absorption and can be potentially applied to acid-resisting bricks except for acid-resistance left to be improved. The elevated curing temperature and the prolonged curing time are both beneficial to develop the mechanical strength as well as the moderately increased forming pressure and quartz sand/fly ash ratio. Being pretreated at elevated temperature for proper time before press forming improves the mechanical strength and reduces the water absorption greatly.

Abstract: Three-dimensional CAD systems contribute considerably to the detailed design processes of products. They are applied to the construction of 3D design models which are also utilized for design evaluation using a CAE system and for NC data generation using a CAM system. Since the functions of 3D CAD systems for constructing 3D models are increasingly being enhanced, they enable designers to easily construct 3D product models without design expertise. In detailed design work, designers are required not only to exactly define product shapes but also to assign attribute information such as dimensional tolerance, geometrical tolerance, roughness, machining process to be performed etc., which are essential for the manufacturing process. However, inexperienced designers often find it extremely hard to determine optimum attribute values and design values. In addition, it is more difficult to construct the required die/mold from the desired product shape taking into account forming errors caused by shrinkage during plastic injection and springback during press forming. This paper proposes a method to automatically assign required attribute information to each part of a designed product, to assist the model construction of a die/mold from a product shape, and to provide design support information on each part of a designed product to a designer. The proposed method is realized by assigning a Function Feature to each part; all the function features proposed in this paper are original. A CAD system based on the proposed method for injection molding and press forming was developed, and results of simple design experiments confirmed the usefulness of the CAD system and function features

Abstract: The square-cylindrical cup of AZ31 Mg alloy with a depth of 50mm and a width of 50 mm was successfully deep drawn from a rolled sheet with a thickness of 0.5 mm using a hydraulic press machine with a capacity of 60 tons. The blank was heated between the die and the blank holder kept in a temperature of 300 oC .The forming time was about 3 seconds. The fine-grained microstructure was observed at the corner with a sever strain. The grain refinement caused by the dynamic recrystallization contributed to generate high strain-rate superplasticity.