Analysis of automobile injection mold
We all know that the automobile is very dependent on the application of plastic parts. At the same time, the automobile products are constantly updated. Only by mastering the key points and difficulties in the production of plastic parts can the mold production meet the development needs of the automobile industry.
Injection mold design based on the foundation
1.1 the design of plastic products is the focus
Plastic products are definitely a key link in the design of injection moulds. For the design of plastic products, the requirements are nothing more than to simplify the model of plastic products as much as possible, especially the sag and undulation design is better not to appear in the design scheme of plastic products.
Plastic products in the design of simple request is a general direction, because there are so many small link in the design of plastic products, facilitation is designed for plastic products every detailed link request, on the basis of the requirements to meet the basic requirement of each link, such as injection mold on its thickness design, will be at the same time in the evolution of make mold wall thickness reach even as far as possible, avoid inappropriate uneven glue.The stiffness and hardness also need to meet the standards, which is a key link to guarantee the quality of plastic parts.
1.2 classification of plastic products in structural design
The inner and outer sides of plastic products should be in accordance with the demoulding standard, which is more conducive to the demoulding.In order to make its appearance smooth and free from friction, plastic products as far as possible in the curve and texture to achieve streamline and smooth.Plastic products have sharp corners, these corners are round corners, for the radian problem in the plastic products on both sides of the surrounding Angle, radian tension should be greater, it is very necessary.
The basic requirements of a molding tool for parts
On the strength and hardness to achieve a certain standard, otherwise cannot undergo friction, affect construction quality, the lowest hardness requirement cannot lower than HRC35, rare special demands on the hardness of more than 50 ~ 52 HRC, after molding, products in to make its surface luster, can be done by polishing, also need polishing and mold parts, product samples can't deviate from the requirements, and then through the management and construction technology in improving production efficiency and cost savings.
Number of clear cavities
The method of determining the number of mold cavities can use the entire injection machine and then determine the number by the amount of injection and the rated clamping force of the injector.Other factors, such as molding process, precision and maintenance, as well as economy, should be incorporated into the number of cavity models.
Identify the fractal line and mold parting surface
Fractal line can be determined according to the shape of the parts, the function of fractal line is no more than to make the product into two parts, the existence of the same dividing line.The two parts are one part in the fixed mold forming, and the other part is the moving mold forming.To obtain the mold parting line can be used fractal line, with the fractal line in two areas around the mold scanning to determine the mold parting surface.
4.1 matters needing attention in the design of parting surface
Step parting surface usually needs 3 ~ 5 degree Angle of insertion and penetration in the face of step parting surface, and the Angle cannot be less than 1.5 degree.Sometimes multiple step surfaces appear simultaneously in A fractal surface. In this case, Angle A is applied at the same Angle, which makes the processing easier and more convenient.
Special attention should be paid to the mold parting surface, which is to ensure that each surface has a sealing distance, and also to guarantee the validity of that distance. In this way, the plastic melt will not flow out easily during the injection process. The name of sealing distance is corresponding to this efficiency, and the material can be blocked up.In the process of creating the fractal surface, if you encounter a fractal surface with a large difference in height, such as surface, ramp and step, whether one or more, you must set a reference plane for it, so that it can be easy to process and measure.
4.2 basic principles of parting surface design
The moulds of moulded plastics need to be retained on the semi-die after the moulding. Of course, under the premise of the ejection mechanism, the ejection mechanism semi-die is usually dynamic die, and only the ejection mechanism semi-die which appears in some special cases is on the fixed die.
Some plastic products will be accompanied with metal insert. Since the insert does not have the function of shrinking the convex mold, the shape cavity is usually designed at the dynamic mold side. If it is not set like this, the plastic products will be in the fixed mold area after mold opening.If the coaxiality structure is formed on both sides of the two models, the coaxiality is difficult to guarantee its accuracy, which is mostly caused by manufacturing errors and assembly errors.
There are certain requirements for mold locking, which must be met. In order to meet these requirements, plastic products are generally placed at the clamping place of the dynamic quantitative mold. The placement direction is to choose the direction with small projected area, and the direction with large projected area is to be used for the lateral fractal surface.This can greatly reduce the locking strength, in addition, the parting surface sometimes curved surface, when this kind of phenomenon appear must to add positioning, on the parting surface selection as far as possible not to impact on the plastic shape form of site selection, if plastic products in the shape of a diamond line tangent and cases, the selection is not suitable for classification.
The selection of the fractal surface must be smooth without obvious sharp angles, so that the segmentation will not affect the quality and appearance, although not absolute, but the probability of occurrence is still large.Make sure to properly arrange the size and quantity of the insert.