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The etched material has a large proportion in the production cost of the dishwasher. A barrel of influence on the future dishwasher industry has recently been developed. In addition to its stability, it is also required to check its mechanical properties. Therefore, it is necessary to carry out a fall test. The fully assembled dishwasher will fall from a height of half a meter to the concrete floor, and it is required to replace the non-pound steel as a dishwasher inner bucket. The barrel inside the semi-drum machine must be intact. Due to the required design development cycle is short. WemerPosGh used a dynamic computer simulation program to simulate the drop test. These dynamics 1 prefaces have a significant cost advantage over molded stainless steel inner barrels compared to stainless steel inner barrels. The use of a polypropylene inner barrel not only reduces the welding and forming of the processing program, especially the barrel, but also the corrosion resistance of the polypropylene, which has a long service life, reduces heat conduction and sound transmission, and reduces the use of heat insulation and sound insulation.
2 The application of plastics in household appliances continues to increase the use of plastics in household appliances, from less than the current 30% in the 1960s. A wide variety of plastics have been applied, among which the most widely used ones are human 83, polystyrene and polypropylene.
The reasons for the growth of plastic applications are manifold. Through injection molding thermoforming extrusion and blow molding, plastics can be easily processed into a variety of complex shapes, with thousands of compounds to choose from, and can be designed to meet specific requirements. Due to the use of plastics, many new features have emerged; product performance has improved; and most importantly, product costs have been greatly reduced.
At present, the competition in the white goods industry is extremely fierce, and all manufacturers are striving to improve production efficiency and reduce production costs. The plastic has the characteristics of easy processing, corrosion resistance, etc., which meets these requirements.
3 Application of Polypropylene in the Dish of the Dishwasher Stainless steel is a traditional material for manufacturing the inner tub of the dishwasher. Although it has excellent corrosion resistance, it is costly. There are currently two ways to lower its bucket.
In comparison, the use of polypropylene to make a drum in a dishwasher has a cost advantage, so this method is more advantageous.
4 Main requirements For polypropylene drums, the most important requirement is whether the strength of the material can withstand high temperatures and the processability associated with injection molding.
The nature of the material is usually divided into one aspect. The material properties, processing characteristics, and design characteristics should emphasize that there is a strong correlation between these properties. 2. The material properties are often for the material, and the design properties are In terms of entities, talking about this is inseparable from the size and shape of the product. The processing characteristics are between the nucleating agent without nucleating agent 650010000ppm nucleating agent; talc powder; other nucleating agent 5.2 filler between the selectors refers to the nature of the process, such as crystallization and orientation. The processing characteristics and design characteristics of the village material together constitute the final product.
Each specific application has its own special requirements. Ask how to determine these requirements and find the most cost-effective material solution that meets your requirements. For the inner barrel of the dishwasher, the village material must meet the following requirements, high rigidity, high impact strength, high spring surface quality, good spring scratch resistance, no contact with hot water or builder, no discoloration, heat deformation resistance High performance, stable anti-sedimentation stability, good dimensional stability 5 Newly developed polypropylene material based on the above requirements, developed a substitute for stainless steel to make the inner barrel of the dishwasher 5.1 mechanical properties 350 double 0 is a kind of filled talcum powder New polypropylene material, which has excellent impact resistance and good rigidity. It is very good for builder hot water and cleaning agent. In order to meet the specific requirements of the village, it is necessary to add filler to the polypropylene. It is necessary to consider a number of factors such as the particle size distribution of the particle, the color hardness specific gravity ratio, and the surface modification. Among the many plastic fillers, we have chosen talc as the active filler because the talc-filled polypropylene compound has higher resistance to thermal deformation than the calcium carbonate-filled compound. Although the glass fiber filler has higher heat deformation resistance 3, it is not used because of the poor surface quality of the glass fiber and the cost.
Another reason for using talc as a filler is that it can reduce the crystallization nucleating agent and increase the crystallization temperature and the rate of crystallization. Therefore, the workpiece can be taken out of the mold at a higher temperature, thereby shortening the injection cycle.
The crystallization temperature of unfilled polypropylene is about, while the crystallization temperature of polypropylene filled with talc powder is 120.
Due to the addition of talc powder, there are a large number of nucleation sites in the initial stage of crystallization, so the crystal spherules formed after the addition of talc powder are smaller than the polypropylene without nucleating agent, and the amount is much more.
In addition to talc, other nucleating agents can also be used to increase the crystallization temperature of polypropylene 6, but they are expensive and can cause distortion of the article.
It is generally believed that the main purpose of adding fillers is to reduce costs, which is of course an important factor, but in practice the overall cost is not reduced when fillers are used. Although the filler is generally lower than the price of the polymer, the filling amount of calcium carbonate + talc + glass fiber properties unit tensile modulus of elasticity yield strength yield ductility fracture stress fracture elongation rate flexural modulus impulse strength thermal deformation Intensity Vicat softening point melt index 刖 only volume melt flow index 刖, only the lateral flow direction anisotropic color change In addition to the raw material cost, there is also a part of the processing cost is the cost of adding the filler to the polymer. Therefore, the filled polymer will be treated in the same way as the unfilled polymer 5.3. The inner barrel of the dishwasher must have the highest matching accuracy with the cutlery basket. Only the filler-filled material and gas jet injection molding are used. Only the required precision can be achieved.
During the cleaning cycle, the inner tub of the dishwasher is exposed to a highly corrosive cleaning medium, and the inner barrel material must be able to withstand the corrosion of these cleaning media.
The stability of thermoplastics depends on many factors, including the stress generated by the time-temperature injection of the cleaning agent and the stresses that may be experienced during use.
Exposure to chemicals can cause yellowing, softening, cracking, etc. of the plastic. Once the softening and swelling of the plastic occurs, its weight will increase and the tensile strength will decrease; and cracking or cracking will result in a decrease in the elongation.
Crystalline polymers generally have lower viscosity and flowability, compared to amorphous polymers having higher viscosity and poor chemical resistance. Therefore, a workpiece molded from a crystalline resin is generally low in stress resistance and high in chemical resistance.
Due to the excellent chemical resistance of plastics, especially polypropylene, polypropylene is an economical alternative to stainless steel in the interior of the dishwasher.
Although polypropylene has the highest chemical resistance in all plastics, we still need to find a test method and test system for testing the stability of this plastic. 7. Because there is no special stability. The test system, in the extremely harsh environment of the barrel inside the dishwasher, the polypropylene may also be destroyed and failed.
The test results show that the unstable village material will change color in a short time. Although this discoloration does not affect the mechanical properties of the material, it is a result we do not want, because it will affect the appearance of the product.
In order to evaluate the changes in the properties of the 18350 Jia, throughout the life of the dishwasher, the village material has undergone the following test 6.1 color change test 30, 35 and 40 days, the color change is evaluated by comparing with the new test piece 6.2 machinery The effect of the test detergent on the mechanical properties of 83500 was tested using tensile test specimen F3 4, and the test specimens were placed in the following solutions for 3, 5, 10, 15, 20, 25, 30, 35 and 40 days. Varying yield stress tensile modulus and yield elongation are evaluated by comparison with new test pieces. 6.56.3 Stabilizer migration test Normally, the stabilizer will migrate to the polypropylene surface, which will lose its usefulness. The effect of the detergent on the migration of the stabilizer was placed in 8080, 2 for different times, and its thermal stability was evaluated by comparison with a new test piece.
6.4 Yellowing test The polypropylene is placed in a silo. If the temperature of the silo is raised, the polypropylene will yellow. To test this effect, the square test pieces of 8018, 12 were placed in hot air of 150 for 3 days, and then the color of the test piece was compared with the new test piece.
6.5 Results of mechanical test In all kinds of solutions, the relative modulus of the village material decreased slightly with time, which was the test piece soaked in 3,1 sen 1 builder.
7 Fall test In addition to being resistant to detergents, the mechanical properties of the material must also meet the requirements for use. In this regard, the fall test is particularly important.
The fully assembled dishwasher fell from a height of 0.5 meters on a 10 degree sloping concrete floor. There should be no damage to the barrel inside the dishwasher. We tested different impact positions in the test to simulate the model with a value of 8 times longitudinal strain. , business strain low strain rate test, time from left to right 95 弋 water, 8, 8! Solution, help solution, olive oil test, time from left to right 95 water, 91 solution, help solution, olive oil 8,8 wash solution, sputum oil collision occurred on the right side of the dish The impact speed of the machine is calculated by the following formula. Since the development of a new type of dishwasher inner bucket must be completed in the shortest time, a dynamic computer simulation program is used to simulate the fall test, just like a computer simulation of a car fall test in the automotive industry.
130. 7 Drinks 31 can be used for these calculations. This is a general explicit finite element analysis program used to simulate the nonlinear dynamic response of structures and mechanical components.
Based on these kinetic calculations and simulations, we can directly design the inner tub of the dishwasher without the need for actual testing, which greatly reduces development time and development costs.
7.1 Village data to be calculated Currently, when engineering polymers need to be applied to various structures, it is necessary to understand the strain rate of the material and the deformation of the plastic caused by temperature. The home appliance industry requires shorter development time and lower development costs. Therefore, in the development process of the product, it is more and more important to adopt a computer-aided engineering method such as a fall simulation.
However, traditional human tools and methods are based on the properties of steel and other metals. Compared with metals, plastics have greater viscoelasticity and viscoplasticity, and in general, schools, disasters 2. The ridiculous ruthless ruthenium ruthenium from the field D shell AI due to the lack of material data under high strain rate conditions, most of the fall simulation uses material data under quasi-static test conditions. Usually, the simulation results are not ideal when used to deal with polymer behavior under conditions of high stress, high strain rate or high load rate. In actual use, components are placed under a variety of load rates, from low load static loads to high speed impact loads.
Generally, under high strain rate conditions, thermoplastics may become hard and fail due to relatively small stresses.
Therefore, we need to obtain material data under strain rate and temperature changes. 1 The university has developed a method for determining material data at high strain rates, which is a reliable basis for calculation and simulation.
7.2 Inspection of material data reliability In order to verify the reliability of the above material data, an injection molded part with a length of 230 mm, a height of 51, and a thickness of 25 was tested. Record the relationship between the force and time under the dynamic load of the box. The actual deformation is then compared to the simulation of the component under dynamic loading. 13. From 13 we can see that there is a strong correlation between the simulation and the real deformation. The sample of the village material is calculated after obtaining such a good test result, and the reliability of the calculation can be ensured.
7.3 Dynamic calculation results Stress distribution at 0.0105 seconds The computer model used for calculation consists of the most important 29 components that make up the dishwasher. 14. The component manufacturer transmits the 0 to 0 data for each individual component to the main calculation module. These individual components are designed by user 0035, and data exchange is performed by 0 as 1 access software. Data input for all components, 19.0 for screening.
The entire model contains approximately 26,000 various factors and 28,000 nodes.
The solver is used, 7 to 4.7, which is the collision simulation solver in the middle.
By calculation, the load on each individual component can be accurately calculated.
In addition to this, areas of excessive deformation in the part can be positioned and then improved by suitable construction theory.
condition. The calculations determine the stress on each component in the dishwasher. Calculation 8 mold design In addition to the fall simulation, we also calculated the mold through the elbow, 1 volume. This program is part of the 0 person plastic injection molding process simulation program, which has been widely used in the injection molding industry.
8.1 Injection molding analysis First, the model is converted into a finite element model containing all the main details and wall thickness. By analyzing the positions of the injection ports of various existing products, the optimal injection port position and the supply are calculated. Material system requirements.
Simulating and investigating the movement of the plastic melt as it is injected into the mold or cavity is a very effective means of allowing us to clearly see how the melt is injected into the mold or cavity. We require balancing the melt flow to prevent overfilling of the material in the mold, which can otherwise lead to injection molding defects. In the usual case, the direction of motion of the melt when it is injected into the mold or cavity is not easy to observe, especially for the wall thickness, which is based on the calculation results. The results of these animations show that the melt is in the part. The path of the flow.
9 Conclusions This project uses dynamic numerical simulation method when designing the inner force of the main force of the dishwasher using the new polypropylene material. The inner barrel can be tested on the computer without actual test, and all the test results are Satisfactory. The measurement of the parameters necessary for the material was also successfully completed. All of this does not cost a lot of money, and the data obtained can be used in future designs.
裘çµå…‰ compiled from the acetylene national electric technology conference proceedings 2002 editor Xu Hang
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