Injection molding is a process in which a molten plastic is injected into a closed mold having a relatively low temperature through a nozzle under high pressure. Both thermoplastics and thermosets can be injection molded. It can be used to make various box-type packaging buckets and pails, such as various pails boxes and small boxes mould. For box-type packaging containers, China bucket mold manufacturers will consider the following aspects in bucket mould structural design.
1. The wall thickness of the bucket mould
The design of the wall thickness mainly considers three aspects: one is thickness; the other is uniformity; the third is gentle transition.
1 Thickness: The wall thickness of the bucket is mainly determined by its use, plastic type, structure and so on. For thermoplastics, generally not less than 0. 6mm, often choose 2~4mm; for thermosetting plastics, because of its poor fluidity, the thickness is larger, the small pieces are 1. 6~2. 5ram, the large pieces are 3. 2 ~ 8mm, the maximum is no more than 10mm.
2 Uniformity: The uniformity of wall thickness has a great influence on the quality of the bucket. If the thickness difference of a bucket is too large, the shrinkage will be uneven, causing defects such as deformation and crack. Therefore, the structure should be designed with an equal thickness structure.
3 Smooth transition: In some buckets, some parts must have different thicknesses due to structural requirements, such as the bucket turning point. At this time, a gentle transition should be adopted to avoid the sudden change of the section.
2. Improve stiffness of the bucket
The plastic is relatively flexible, the bucket is made of poor rigidity, and the turnover box type container sometimes has a large load capacity, so various measures for improving the rigidity should be adopted in the structure.
1 Add reinforcement: Reinforcement can enhance the strength and rigidity of the container. The basic requirements for the ribs are: the number should be more, the wall thickness should be thin, the height should be short, and the slope should be sufficient. The bottom of the rib should be a circular arc transition. The direction of the rib should be consistent with the flow direction to improve the plastic. toughness;
2 Improve the shape: the box-shaped bucket is mostly rectangular thin-walled parts, which are easy to be deformed. Various reinforcement measures should be taken to slightly extend the four side walls of the bucket to improve the rigidity; it is a strip shape on the side wall to prevent distortion. Enhancement; edge reinforcement at the edge of the bucket to prevent deformation of the mouth; bottom reinforcement at the bottom of the bucket designed in a corrugated, arched shape.
3 Reasonable support: The bottom area of the box-shaped bucket is large, but it is unreasonable to use the whole bottom surface as the support. Because the bottom is slightly curved, it is not flat. Therefore, the surface support should be changed into a line support or a point support, and the convex side support (ie, the line) Support); raised foot support (ie point support); the height of the protrusion is generally 0. 3 ~ 0. 5mm.
4 Corner: The corner is the intersection of two faces or three faces. Regardless of the shape of the bucket, the intersection of the faces must be rounded, which can greatly improve the rigidity of the bucket and improve the plastic filling model. Sex, and can disperse stress and reduce deformation.
3. Demoulding slope
In order to facilitate the demolding of the molded part, a suitable draft angle must be considered when designing the bucket. The draft is too small, the demoulding is difficult, and the surface of the bucket is damaged; if it is too large, the dimensional accuracy is affected.
The draft angle varies depending on the shape of the plastic part, the type of plastic, the mold structure, the surface roughness, the molding method, and the like. Generally speaking, the commonly used slope of the plastic part along the demolding direction is 1o~1.5o, and the minimum is not less than 0.5o.
