Structural Scheme Optimization Design for the Stationary Platen of a Precision Plastic Injection Molding Machine

The current development of precision plastic injection molding machines mainly focuses on how to save material and improve precision, but the two aims contradict each other. For a clamp unit, clamping precision improving depends on the design quality of the stationary platen. Compared with the parametric design of stationary platen, structural scheme design could obtain the optimization model with double objectives and multi-constraints. In this paper, a SE-160 precision plastic injection molding machine with 1600 kN clamping force is selected as the subject in the case study. During the motion of mold closing and opening, the stationary platen of SE-160 is subjected to a cyclic loading, which would cause the fatigue rupture of the tie bars in periodically long term operations. In order to reduce the deflection of the stationary platen, the FEA method is introduced to optimize the structure of the stationary platen. Firstly, an optimal topology model is established by variable density method. Then, structural topology optimizations of the stationary platen are done with the removable material from 50%, 60% to 70%. Secondly, the other two recommended optimization schemes are given and compared with the original structure. The result of performances comparison shows that the scheme II of the platen is the best one. By choosing the best alternative, the volume and the local maximal stress of the platen could be decreased, corresponding to cost-saving material and better mechanical properties. This paper proposes a structural optimization design scheme, which can save the material as well as improve the clamping precision of the precision plastic injection molding machine.

IMPROVE THE KINETIC PERFORMANCE OF THE PUMP CONTROLLED CLAMPING UNIT IN PLASTIC INJECTION MOLDING MACHINE WITH ADAPTIVE CONTROL STRATEGY

The kinetic characteristics of the clamping unit of plastic injection molding machine that is controlled by close loop with newly developed double speed variable pump unit are investigated. Considering the wide variation of the cylinder equivalent mass caused by the transmission ratio of clamping unit and the severe instantaneous impact force acted on the cylinder during the mold closing and opening process, an adaptive control principle of parameter and structure is proposed to improve its kinetic performance. The adaptive correlation between the acceleration feedback gain and the variable mass is derived. The pressure differential feedback is introduced to improve the dynamic performance in the case of small inertia and heavy impact load. The adaptation of sum pressure to load is used to reduce the energy loss of the system. The research results are verified by the simulation and experiment, The investigation method and the conclusions are also suitable for the differential cylinder system controlled by the traditional servo pump unit.

Fabrication and Characterization on Physico-Mechanical and Structural Properties of Sawdust Reinforced Acrylonitrile Butadiene Styrene (ABS) Composites

The sawdust reinforced Acrylonitrile Butadiene Styrene (ABS) composites were prepared by using hot press molding machine for five different wt% (0%, 5%, 10%, 15% and 20%) at 180°C temperature and 50 KN load. Sawdust was collected from local saw mill of Savar, Dhaka, Bangladesh and ABS polymer was collected from local market of Dhaka, Bangladesh. In this study, different properties of composites like physical (bulk density and water absorption), mechanical (tensile properties and hardness) and structural (Fourier Transform Infrared Spectroscopy) properties were studied. The bulk density of composites was not altered consistently and it gave greater value for 5% and 20% composites. The water absorption enhanced for all composites with the accumulation of fiber content and soaking time. The reduction of tensile strength and Leeb’s rebound hardness of the composites were observed with the increase of the fiber content in all compositions. Maximum (%) of elongation was found for 5% composite, and then it gradually decreased;however, elastic modulus increased with the increased of fiber content in composites. Fourier Transform Infrared (FTIR) spectroscopy study was done for structural characterization. It was found that there was a new bond (C≡C) stretching formed for 20% composite;moreover, C-H rocking for 0% composite was broken for all other composites after the addition of sawdust in ABS polymer matrix.

Theoretical modeling of cutting temperature in high-speed end milling process for die/mold machining

A parametric model of cutting temperature generated in end milling process is developed according to the thermal mechanism of end milling as an intermittent operation, which periodically repeats the cycle of heating under cutting and cooling under non-cutting. It shows that cutting speed and the tool-workpiece engagement condition are determinative for tool temperature in the operation. The suggested model was investigated by tests of AlTiN coated endmill machining hardened die steel JIS SKD61, where cutting temperature on the flank face of tool was measured with an optical fiber type radiation thermometer. Experimental results show that the tendency of cutting temperature to increase with cutting speed and engagement angle is intensified with the progressing tool wear.

A Tool Path Re-generation Algorithm for Die & Mold Machining

Facing the challenges of a shorter product design a nd manufacturing lead-time, many mold companies are using 3-D CAD/CAM software s ystems in design and manufacturing. A new product file is often issued to the mo ld design department before it is completely finalized and the design may have t o be iterated many times during the mold design and making processes. In practic e, if a mold has been modified, all the tool paths that cover the modified regio n must be re-generated, no matter how small the modified region may be. With th e available tool path generation systems, if a tool path needs to be re-generat ed, all the cutter location (CL) points must be re-calculated, and none of the original CL points can be re-used. It would require as much time to re-gen erate the modified tool path as in the original case. On the other hand, the mod ified region is usually quite small compared with the entire mold. The complete re-generation process is therefore highly unproductive and time-consuming. This paper proposes an efficient tool path re-generation approach for 3-axis d ie and mold machining. It is assumed in this research that a gouge-free too l path has been generated for the original mold and the same ball end-mill is to be used to generate the tool path for the modified mold. It is shown in th is work that if the boundary of the modified region is interference-free, the a ffected CL points are enclosed by a set of CL points which correspond to the poi nts on the boundary of the modified region. An efficient tool path re-generatio n algorithm was developed in this research. With this algorithm, a closed CL cur ve is first generated from the boundary of the affected region. The CL points fo r the original mold are then analyzed by comparing the x and y values with the b oundary of the affected CL points. If the CL points are not affected by the modi fication, they are output to the new CL file directly. Otherwise, they are remov ed and replaced by the new CL points. The algorithm has been tested using severa l industrial parts, and results show that it is efficient, robust, and the re-g enerated tool path is gouge-free and smooth.

Model predictive control of servo motor driven constant pump hydraulic system in injection molding process based on neurodynamic optimization

In view of the high energy consumption and low response speed of the traditional hydraulic system for an injection molding machine,a servo motor driven constant pump hydraulic system is designed for a precision injection molding process,which uses a servo motor,a constant pump,and a pressure sensor,instead of a common motor,a constant pump,a pressure proportion valve,and a flow proportion valve.A model predictive control strategy based on neurodynamic optimization is proposed to control this new hydraulic system in the injection molding process.Simulation results showed that this control method has good control precision and quick response.