Automotive Mould
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In the development of automobile industry, demand for plastic parts is increasing day by day, because application of plastic parts in construction of automobiles is very high, that is to say, quality of plastic parts has a huge role in promoting development and construction of automobile field, which requires quality assurance in production of plastic parts, and quality of plastic parts is determined by mold. There are not a few cases where plastic parts produced cause losses to various fields during application process due to mistakes of mold. It is very helpful for my country's economic development to analyze molds for production of plastic parts in order to improve quality and efficiency of plastic parts.
We all know that automobiles are very dependent on application of plastic parts. At the same time, automobile products are constantly updated. Only by mastering key and difficult points of mold production of plastic parts can mold production meet development needs of automotive industry.
1 Basics of injection mold design
1.1 Design of plastic products is focus
Plastic products are definitely a key link in design of injection molds. Design of plastic products requires nothing more than to simplify model of plastic products as much as possible, especially design of concave and undulating should not appear in design scheme of plastic products.
Requirement of simplicity in design of plastic products is a general direction, because there are many small links in design of plastic products. On the basis of this requirement, basic requirements of each link are met. For example, in design of thickness of injection mold, it is necessary to make wall thickness of mold as uniform as possible while evolving to avoid inappropriate glue positions with uneven thickness. Stiffness and hardness also need to meet standards, which is a key link to ensure quality of plastic parts.
1.2 Classification of plastic products in structural design
Inner and outer sides of plastic product must have a demoulding slope that meets demoulding standard, which is more conducive to demoulding. In order to make appearance smooth and demoulding is not hindered by friction, plastic products should be as streamlined and smooth as possible in terms of radian and texture. Plastic products have sharp corners, and these corners are rounded. For radian problem, in peripheral corners of inner and outer sides of plastic product, radian tension should be larger, which is very necessary.
2 Basic requirements of a forming mold for parts
Strength and hardness must reach a certain standard, otherwise it will not be able to withstand friction, which will affect construction quality. Minimum hardness requirement should not be lower than HRC35, and hardness of very few special requirements should be above 50~52HRC. After product is formed, surface should be glossy, which can be achieved by polishing. In addition, cavity part needs to be polished. Sample of product cannot deviate from product requirements, then management and construction technology are used to improve production efficiency and save costs.
3 Number of clear cavities
Method of determining number of cavities can use all injection machines, then confirm number of them by amount of injection and rated clamping force of injection machine. Other factors need to be combined in process of number of model cavities, such as: molding process, precision and maintenance, and economy.
4 Identify fractal line and mold parting surface
Determination method of fractal line can be determined according to shape of part. Function of fractal line is nothing more than to divide product into two parts with same dividing line. The two parts that are divided into one part are formed by fixed mold, and the other part is formed by movable mold. To obtain parting surface of mold, fractal line can be used, and parting surface of mold can be determined by scanning fractal line around the two molds.
4.1 Precautions for parting surface design
Step parting surface generally needs to have an insertion inclination angle of 3 to 5 degrees when facing step parting surface, and angle cannot be lower than 1.5 degrees. Sometimes multiple step surfaces appear in a parting surface at the same time. In this case, same angle is used to act on angle A, which makes processing easier and more convenient.
There is one part of parting surface of mold that needs special attention, that is, to ensure that each same surface has a sealing distance, and at the same time to ensure effectiveness of this distance, so that plastic melt does not easily flow out during injection process. Name of sealing material distance corresponds to this effect, and material can be blocked. In process of creating parting surface, if there is a parting surface with a large difference in height such as a curved surface, an inclined surface, and a step, whether it is one or more, a reference plane must be set for it, which can facilitate processing and measurement.
4.2 Basic principles of parting surface design
Molding plastic needs to be retained on half mold after mold is opened. Of course, this is based on premise of a push-out mechanism. Generally, half-mold of push-out mechanism is a movable mold, and only half-mold of push-out mechanism that appears in a few special cases is on fixed mold.
Some plastic products will come with metal inserts. Since inserts do not have function of shrink wrapping punch, shape cavity design is usually on the side of movable mold. If it is not set in this way, plastic product will be in fixed mold area after mold is opened. Once this happens, demolding becomes very difficult. If coaxiality structure is inside movable mold or fixed mold, if it is formed on both sides of the two molds, coaxiality is difficult to ensure its accuracy. This situation is mostly due to manufacturing errors and assembly errors.
There are certain requirements for locking of mold, which must be satisfied. In order to meet this requirement, plastic products are generally placed at clamping part of ground motion quantitative mold. Direction of placement is selected in direction with a smaller projected area, and direction with a large projected area is placed on lateral fractal surface. This can greatly reduce locking force. In addition, parting surface sometimes has a curved surface. When this phenomenon occurs, a positioning mechanism must be added, selection of parting surface should not affect shape of plastic product as much as possible. If plastic product has diamond lines and tangent lines in its shape, it is not suitable for selection of parting surfaces.
Parting surface must be selected to be relatively smooth and without obvious sharp corners, so that segmentation will not affect quality and shape. Although it is not absolute, probability of occurrence is still high. Be sure to arrange size and quantity of inner mold inserts reasonably.
We all know that automobiles are very dependent on application of plastic parts. At the same time, automobile products are constantly updated. Only by mastering key and difficult points of mold production of plastic parts can mold production meet development needs of automotive industry.
1 Basics of injection mold design
1.1 Design of plastic products is focus
Plastic products are definitely a key link in design of injection molds. Design of plastic products requires nothing more than to simplify model of plastic products as much as possible, especially design of concave and undulating should not appear in design scheme of plastic products.
Requirement of simplicity in design of plastic products is a general direction, because there are many small links in design of plastic products. On the basis of this requirement, basic requirements of each link are met. For example, in design of thickness of injection mold, it is necessary to make wall thickness of mold as uniform as possible while evolving to avoid inappropriate glue positions with uneven thickness. Stiffness and hardness also need to meet standards, which is a key link to ensure quality of plastic parts.
1.2 Classification of plastic products in structural design
Inner and outer sides of plastic product must have a demoulding slope that meets demoulding standard, which is more conducive to demoulding. In order to make appearance smooth and demoulding is not hindered by friction, plastic products should be as streamlined and smooth as possible in terms of radian and texture. Plastic products have sharp corners, and these corners are rounded. For radian problem, in peripheral corners of inner and outer sides of plastic product, radian tension should be larger, which is very necessary.
2 Basic requirements of a forming mold for parts
Strength and hardness must reach a certain standard, otherwise it will not be able to withstand friction, which will affect construction quality. Minimum hardness requirement should not be lower than HRC35, and hardness of very few special requirements should be above 50~52HRC. After product is formed, surface should be glossy, which can be achieved by polishing. In addition, cavity part needs to be polished. Sample of product cannot deviate from product requirements, then management and construction technology are used to improve production efficiency and save costs.
3 Number of clear cavities
Method of determining number of cavities can use all injection machines, then confirm number of them by amount of injection and rated clamping force of injection machine. Other factors need to be combined in process of number of model cavities, such as: molding process, precision and maintenance, and economy.
4 Identify fractal line and mold parting surface
Determination method of fractal line can be determined according to shape of part. Function of fractal line is nothing more than to divide product into two parts with same dividing line. The two parts that are divided into one part are formed by fixed mold, and the other part is formed by movable mold. To obtain parting surface of mold, fractal line can be used, and parting surface of mold can be determined by scanning fractal line around the two molds.
4.1 Precautions for parting surface design
Step parting surface generally needs to have an insertion inclination angle of 3 to 5 degrees when facing step parting surface, and angle cannot be lower than 1.5 degrees. Sometimes multiple step surfaces appear in a parting surface at the same time. In this case, same angle is used to act on angle A, which makes processing easier and more convenient.
There is one part of parting surface of mold that needs special attention, that is, to ensure that each same surface has a sealing distance, and at the same time to ensure effectiveness of this distance, so that plastic melt does not easily flow out during injection process. Name of sealing material distance corresponds to this effect, and material can be blocked. In process of creating parting surface, if there is a parting surface with a large difference in height such as a curved surface, an inclined surface, and a step, whether it is one or more, a reference plane must be set for it, which can facilitate processing and measurement.
4.2 Basic principles of parting surface design
Molding plastic needs to be retained on half mold after mold is opened. Of course, this is based on premise of a push-out mechanism. Generally, half-mold of push-out mechanism is a movable mold, and only half-mold of push-out mechanism that appears in a few special cases is on fixed mold.
Some plastic products will come with metal inserts. Since inserts do not have function of shrink wrapping punch, shape cavity design is usually on the side of movable mold. If it is not set in this way, plastic product will be in fixed mold area after mold is opened. Once this happens, demolding becomes very difficult. If coaxiality structure is inside movable mold or fixed mold, if it is formed on both sides of the two molds, coaxiality is difficult to ensure its accuracy. This situation is mostly due to manufacturing errors and assembly errors.
There are certain requirements for locking of mold, which must be satisfied. In order to meet this requirement, plastic products are generally placed at clamping part of ground motion quantitative mold. Direction of placement is selected in direction with a smaller projected area, and direction with a large projected area is placed on lateral fractal surface. This can greatly reduce locking force. In addition, parting surface sometimes has a curved surface. When this phenomenon occurs, a positioning mechanism must be added, selection of parting surface should not affect shape of plastic product as much as possible. If plastic product has diamond lines and tangent lines in its shape, it is not suitable for selection of parting surfaces.
Parting surface must be selected to be relatively smooth and without obvious sharp corners, so that segmentation will not affect quality and shape. Although it is not absolute, probability of occurrence is still high. Be sure to arrange size and quantity of inner mold inserts reasonably.