Large-size Parts Research Articles

Sectional multipoint forming technology for large-size sheet metal

Based on the flexibility of multipoint forming, a work piece can be formed in a way section by section, which is named sectional multipoint forming (SMPF) here. With this technique, large-size parts of sheet metal can be manufactured on a small MPF press. In this article, basic principles and deformation characteristics of SMPF are discussed and three typical forming methods are summarized. Partial severe plastic deformation has become the main defect needed to be and wrinkle and dimple have new features in the SMPF process. Numerical simulation is an effective way to predict forming defects. Optimized design of the assortative region can suppress forming defects and improve forming efficiency. Some application examples improved the feasibility of SMPF technology .

Multi-point forming technology for sheet metal

Multi-point forming (MPF) is an advanced manufacturing technology for three-dimensional sheet metal parts. In this paper, an MPF integrated system is described that can form a variety of part shapes without the need for solid dies, and given only geometry and material information about the desired part. The central component of this system is a pair of matrices of punches, and the desired discrete die surface is constructed by changing the positions of the punches though CAD and a control system. Typical examples show the applicability of the MPF technology. Wrinkles and dimples are the major forming defects in the MPF process, but numerical simulation is a feasible way to predict forming defects in MPF. In conventional stamping, the method to form sheet metal with a blankholder is an effective way to suppress wrinkling; and the same is true in MPF. An MPF press with a flexible blankholder was developed, and the forming results indicated the forming stability of this technique. Based on the flexibility of MPF, varying deformation path MPF and sectional MPF were explored that cannot be realized in conventional stamping. By controlling each punch in real-time, a sheet part can be manufactured along a specific forming path. When the path of deformation in MPF is designed properly, forming defects will be avoided completely and large deformation achieved. A workpiece can be formed section by section though the sectional MPF, and this technique makes it possible to manufacture large size parts in a small MPF press. Some critical experiments were performed that confirmed the validity of the two special MPF techniques.

Production of large size parts by MIM process

Extraction method using supercritical carbon dioxide is an efficient and safe extraction method, and began to use many industrial fields. Supercritical fluid has high density like liquid and low viscosity like gas. It can solve solute like liquid and it can go into porous body like gas. Carbon dioxide becomes supercritical state at relatively low temperature and low pressure, and it is harmless to human health and environment. This extraction method is adopted to the debinding process of metal injection moulding (MIM). On this method, powder is mixed with binder and parts are moulded by injection moulding. After moulding, binder is removed from the parts and these are sintered. On these processes, the debinding process is most difficult and time consuming. On conventional thermal debinding, it need several days for debinding process, and it is difficult to produce the part which has the thickness more than 10 mm. Applying this extraction method to the debinding process, production of large parts is possible.

成形・加工のプロセスとその周辺技術 新しい射出成形法 ＱＳＰによる機械構造用焼結低合金鋼の諸特性

Metal Injection Molding (MIM) process is a manufacturing route for mass-production of high density, highperformance, and near net-shaped metal components. However, MIM processes have been still limited in the size of the components. A Quickset process (QSP) has been invented as one of solutions for the issue. A feature of QSP is the manufacturing of large size parts that can not be made by the usual MIM processes based on a thermoplastic binder system. Although assessment of the properties such as strength are important to design the reliable machine structural parts, there are few reports about the properties of the materials produced by QSP at the present time.In this study, the behavior of properties (relative density, hardness, tensile and fatigue strength) for machine structural low alloy steels produced by QSP have been investigated. The tensile strength of QSP alloy steels were equivalent to those of MIM alloy steels. However the fatigue strength of QSP alloy steel was relatively low, because of the coarse pores due to the segregation of binder occurred at water freeze injection molding step.

Special features of the formation of the structure and properties in heat treatment of large preforms of structural steels

Steels for large size parts should provide uninterrupted and reliable operation of them at positive and negative temperatures of the ambient. Traditional methods for obtaining u set of high properties in large preforms are well known. Steels used for these purposes are alloyed with up to 3% Ni and 0. 5% Mo. The high cost of these alloying elements has led to the development of economically alloyed steels with elevated strength and reduced capacity for brittle fracture. A computational method for choosing the materials for large-size forgings and castings is presented.

Effect of the composition on the hardenability and properties of complexly alloyed steel for large-size parts

Large-sin parts are usually produced from steels with high hardenability. Intermediate-carbon improved chromium-nickel steels containing 1–3% Ni are used successfully for this purpose in Ukraine and in foreign countries. However, nickel is an expensive and scarce alloying element. The present work is devoted to steels with different compositions with the aim of choosing the most suitable one for large-size parts. The effect of alloying elements on the hardenability and mechanical properties of steels is investigated. A mathematical model is obtained.

A simulation study of flexible manufacturing systems

This paper presents the results of a simulation study of a flexible manufacturing system (FMS). The FMS considered for the present study includes six machining centers capable of performing a variety of tasks, an automated guided vehicle based material handling system and a single input, single output storage-retrieval system connected to the manufacturing system by conveyors. The model for the study accounts for uncertainties such as stochastic part arrival patterns, variable machining times and machine breakdowns. The system considered for the present study manufactures large size parts. Effects of a change in the layout of the manufacturing cell on the system performance have also been investigated. Time spent for parts in the system is considered as one of the main criteria of the system performance.

Selection of wall thickness of circular dies used in press tools for pressing large-size carbide parts

1. The strength of dies used for pressing carbide components will be adequate if the valuea=r2/r1=1.15. However, strength should not be the only criterion for design as this leads to poor quality of pressed components. Additional calculation of rigidity is essential. 2. The rigidity of dies used for pressing carbide components will be adequate if the valuea=r2/r1=1.3. It is preferable to design only the working zone of the die for rigidity and the remaining portion for strength, i.e., to use dies with variable wall thickness.

Modernization of a revolving press

Large-size parts 370 mm in length can be pressed on the newly modernized revolving press. The output of the press in tonnage has been stepped up since modernization on account of the increased weight of the pressed parts, despite the reduction in the number of revolutions of the table (the pressing cycle has gone up from 1.5 to 2.15 seconds); the quality of the pressed parts has been improved. Experience gained at the Panteleymonovo Plant has shown that this type of revolving press can be made at a pressing pressure of up to 600 tons.