Application of the hottest CAE in automobile plast

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The application of CAE in the manufacturing process of automotive plastic molds

in recent years, China's automotive industry has an increasing demand for plastic molds. The traditional mold design methods have been unable to meet the requirements of product upgrading and quality improvement, and the use of CAE technology has gradually become a major trend. This paper introduces the application characteristics of CAE technology, the methods to solve the problems in injection molding process and two application examples

the automobile and motorcycle industry is the largest mold market, accounting for about half of the whole mold Market in industrialized countries. In 2002, China's automobile production was about 3.2 million, and this year it is expected to reach 3.9 million, with 170 models. Plastic parts have been used more and more widely in cars, but China's large and medium-sized plastic molds for car bumpers, instrument panels, fuel tanks, steering wheels and so on are expected to meet only about 50% of the demand by 2005. The demand of automobile mold market is increasing, and the requirements of products for molds are also higher and higher. The traditional mold design method can not meet the requirements of product upgrading and quality improvement. The design of plastic mold should not only adopt CAD technology, but also adopt CAE technology

the mold filling process simulated by Moldflow part adviser 7.1

cae takes computer software as a tool and simulation as a means to help users predict the work, so as to solve existing or potential problems in engineering. Compared with traditional mold design, CAE technology has unparalleled advantages in improving productivity, ensuring product quality, reducing costs and reducing labor intensity. Moldflow in the United States is a company specializing in plastic molding analysis software (CAE) and consulting. Since 1976, when the world's first set of flow analysis software was released, CAE (Moldflow) has been widely used in automotive, home appliances, electronic communications, chemical industry, daily necessities and other fields

technical application characteristics

the traditional injection molding method is that before formal production, the designer designs the mold based on experience and intuition. After the mold is assembled, it usually needs several mold trials. After finding problems, it is not only necessary to reset the process parameters, but also need to modify the plastic products and mold design. Its disadvantage is to increase the production cost and prolong the product development cycle. CAE (Moldflow) technology has the following application characteristics

provide a complete solution from product design to production

cae (Moldflow) analysis technology can provide a complete solution for the whole production process of product design, mold design and injection molding. Moldflow MPa (product optimization consultant) is a solid based injection mold analysis software, which can accept the solid shape output from any CAD software. Through simulation analysis, the optimized product design scheme can be obtained in a very short time to confirm the surface quality of the product; MPI (injection molding simulation analysis) can simulate and analyze the whole injection molding process on the computer, including filling, pressure holding, cooling, warping, fiber orientation, structural stress and shrinkage, gas assisted and thermosetting plastic flow analysis; MPX (injection molding process control) can be directly connected with the injection molding machine controller for real-time process optimization and quality monitoring

improve the success rate of one-time mold trial

before mold processing, simulate and analyze the whole injection molding process on the computer to accurately predict the filling, pressure holding and cooling of plastic melt, as well as the stress distribution, molecular and fiber orientation distribution, shrinkage and warpage deformation of products, so that designers can find problems as soon as possible and modify the parts and mold design in time, Instead of waiting until after the trial mold to repair the mold. It is of great technical and economic significance to reduce or even avoid mold repair and scrap, improve product quality, reduce costs, and maintain the highest performance of finished parts

solve the problems in the injection molding process

Product Design

product designers can use flow analysis to solve the following problems:

* can the products be fully filled? This ancient problem is still concerned by many product designers, especially the designers of large-scale products such as lids, containers, furniture, etc

* what is the actual minimum wall thickness of the workpiece? If thin-walled parts can be used, the material cost of parts can be greatly reduced. Reducing wall thickness can also reduce the cycle time of parts, so as to improve production efficiency and reduce the cost of plastic parts

* is the gate position appropriate? By using CAE analysis, the product designer can fully select the gate position in the design and ensure the aesthetic characteristics of the design

mold design and manufacturing

* good filling form: for any injection molding, the most important thing is to control the filling method to make the molding of plastic parts reliable and economical. Unidirectional filling is a good injection molding method, which can improve the unidirectional and stable orientation of molecules in plastic parts. This filling form helps to avoid warping deformation caused by different molecular orientations

* optimal gate position and number: in order to control the filling mode, the mold designer must choose the gate position and number that can realize this control. CAE analysis can enable the designer to have a variety of gate position selection schemes and evaluate their impact

* optimal design of runner system: the actual mold design often needs to weigh various factors repeatedly to make the design scheme perfect as far as possible. Flow analysis can help designers design runner systems with pressure balance, temperature balance or both pressure and temperature balance, and can also evaluate the shear rate and friction heat in the runner, so as to avoid material degradation and excessive melt temperature in the mold cavity

* optimal design of cooling system: by analyzing the influence of cooling system on flow process, optimize the layout and working conditions of cooling pipeline, so as to produce uniform cooling, thus shortening the forming cycle and reducing the internal stress of products after forming

* reduce the overhaul cost: improving the possibility of successful mold trial is a major advantage of CAE analysis. Repeated mold trial and repair will cost a lot of time and money. In addition, the mold without repeated mold repair has a long life

injection molding

* wider and more stable processing "margin has greatly improved the effectiveness of management and utilization": flow analysis puts forward a target trend for the main injection molding processing parameters such as melt temperature, mold temperature and injection speed. Through flow analysis, the injection molding operator can evaluate the correct value of each processing parameter and determine its variation range. Together with mold designers, they can use the most economical processing equipment to set the best mold scheme

* reduce the stress and warpage of plastic parts: select the best processing parameters to minimize the residual stress of plastic parts. The residual stress usually makes plastic parts warp and deform after forming, and even fail

* save materials and reduce excessive mold filling: the design of runner and cavity adopts balanced flow, which helps to reduce the use of materials and eliminate the warpage caused by local excessive injection

* minimum runner size and recycled material cost: flow analysis helps to select the best runner size, so as to reduce the cooling time of the plastic in the runner part, thus shortening the whole injection molding time, and reducing the volume of the plastic in the runner part that becomes recycled material or waste

application example

automotive ventilation trim cover

the parts are automotive ventilation trim cover, which adopts gas assisted injection molding. The requirements include: determining the position and quantity of gate and air port, predicting the penetration of gas in the airway and process parameters

* modeling: Moldflow directly reads CAD models through graphical interfaces. The model and gating system are shown in Figure 1. The initial design of the gating system uses one side gate and two air gate positions

* input process conditions: the maximum injection pressure is 55MPa, the gas injection pressure is 20MPa, the mold temperature is 50 ℃, the melt temperature is 230 ℃, the delay time is 2.5 seconds, the equivalent diameter of the airway is 9.6mm, and the cooling time is 22 seconds

* analysis and calculation: according to the front peak advance diagram of melt flow, the melt flow can be seen dynamically, and the enterprise value can also be realized. "Under the blue sky, the isoline diagram can be used to judge whether the flow is uniform. According to the distribution diagram of plastic skin layer ratio, the gas filling in the mold cavity can be observed to determine the gas injection stop and pressure holding pressure. Through Moldflow analysis, we can determine the reasonable gate and air port position, predict the penetration of gas along the stiffener, further improve the market competitiveness, as well as the gas pressure, clamping force, etc

automobile dashboard

for large molds, the parameters of flow, pressure maintaining, cooling and other aspects need to be strictly controlled, otherwise, a little carelessness may cause defects such as uneven cavity filling, uneven cooling, deformation and large residual stress. Through the simulation and analysis of the flow process, cooling process and pressure maintaining process, the screw speed position curve, pressure maintaining curve and cooling system are optimized, and the warpage deformation is analyzed and calculated

the product material is ferr/pp lpp20bc07hbbk, and the product size is large (1.4m long). The original scheme uses 10 gates and hot runner. The filling in the original scheme is unbalanced and uneven, and the pressure distribution is also uneven. The maximum temperature difference on the surface of the product is 40.30 degrees. The temperature difference is large. The area with high temperature needs to be cooled more, and the deformation is also large, which cannot meet the requirements of dimensional accuracy

through Moldflow optimization of screw speed position curve, pressure maintaining curve, runner system and cooling system, ideal filling effect is obtained, and the cooling effect is also good. The temperature distribution on the surface of the product is relatively uniform, the temperature difference drops to 26.67 degrees, and the warpage deformation is also greatly reduced. (end)

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