1. Container wall thickness
The design of wall thickness mainly considers three aspects: first, thickness; The second is uniformity; The third is a smooth transition.
① Thickness: The wall thickness of the container is mainly determined by its use, plastic type and structure. For thermoplastics, it should generally not be less than 0. 6mm, often choose 2 ~ 4mm for thermosetting plastics, because of poor fluidity, the thickness is larger, and a small part is 1. 6~2。 5 memory, 3 for large items. 2 ~ 8 mm, with the maximum not exceeding 10 mm. ..
② Uniformity: The uniformity of wall thickness has a great influence on the quality of containers. If the thickness difference of the container is too large, it will cause uneven shrinkage and produce defects such as deformation and cracks. Therefore, the structure with equal thickness should be adopted as far as possible in structural design.
③ Smooth transition: In some containers, due to structural needs, the thickness of some parts must be different, such as the turning point of the container, smooth transition should be adopted to avoid sudden change of cross section.
2. Improve rigidity
Plastic is flexible, and the container made of it has poor rigidity, while the container of turnover box sometimes has great bearing capacity, so various measures should be taken to improve the rigidity in structure.
① Reinforcing ribs: Reinforcing ribs can enhance the strength and rigidity of containers. The basic requirements for reinforcing ribs are as follows: the number should be large, the wall thickness should be thin, the height should be short, there should be enough inclination, the bottom of the ribs should be in an arc transition, and the direction of reinforcing ribs should be consistent with the direction of material flow to improve the toughness of plastics;
② Shape improvement: box-shaped containers are mostly rectangular thin-walled parts, which are easy to deform. Various reinforcement measures should be taken to make the four side walls of the container protrude slightly to improve the rigidity; It is a strip-shaped reinforcing rib on the side wall to prevent deformation; The edge of the container edge is reinforced to prevent the deformation of the container mouth; The bottom of the container is designed to be corrugated and arched for bottom reinforcement.
(3) Reasonable support: The bottom area of the box container is large, but it is unreasonable to use the whole bottom as support. Because the bottom is slightly arched, it will be uneven, so the surface support should be changed to line support or point support plus convex edge support (that is, line support); Raised foot support (i.e. point support); The height of the bump is usually 0. 3~0。 Five millimeters.
(4) Angle: Angle refers to the intersection of two or three surfaces. No matter what shape the container is, the intersection of all curved surfaces must adopt fillet transition, which can greatly improve the rigidity of the container, improve the filling performance of plastic, disperse stress and reduce deformation.
3. Demoulding slope
In order to facilitate the demoulding of plastic parts, the proper demoulding slope must be considered when designing containers. The demoulding slope is too small, which makes demoulding difficult and damages the surface of the container; Too much will affect the dimensional accuracy.
The demoulding inclination varies with the shape of plastic parts, plastic types, mold structure, surface roughness and molding method. Generally speaking, the slope of plastic parts along the demoulding direction is 1? ~ 1.5? , the minimum is not less than 0.5? .