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The structure of the injection mold design should pay attention to what
by：CSSSLD
2021-01-23
Injection molding is also called the injection molding, molten plastic, at high pressure through the nozzle into the low temperature within the closing of the mold and molding.
Thermoplastic and thermosetting plastic injection molding are available, and it mainly on packaging container production can produce all kinds of box-type packaging containers, such as turnover box, a small box.
For box packaging container, the main structure design should consider the following aspects.
1. Injection products of wall thickness
of wall thickness are considered in the design of the three aspects: one is the thickness. Second, the uniformity; Three is a smooth transition.
1.
: the thickness of wall thickness of the main product is decided by its purpose, plastic types, structure, etc. For thermoplastic, usually should not be less than 0. 6 mm, often choose 2 ~ 4 mm; For thermosetting plastics, because of its liquidity is poorer, the thickness of the bigger, small to 1. 6 to 2. 5 ram, big 3. 2 ~ 8 mm, maximum of no more than 10 mm.
2) uniformity: the uniformity of wall thickness had a great influence on the quality of the container, a container if the thickness difference is too big, can make the uneven contraction, deformation, cracks and other defects. Therefore, in the structure design should be as far as possible when using thickness structure.
3. Gentle transition: in some containers, thickness of some parts due to the structure need to must not at the same time, such as container turning point, when the smooth transition should be adopted to avoid cross section mutation.
2. Improve the injection molding container stiffness
plastic is more flexible, containers made of stiffness is poorer, and turnover box class container capacity and large, sometimes in should take various measures to improve rigidity of the structure.
1.
add reinforcement, reinforcement can improve the strength and stiffness of the vessel. Basic requirements of stiffener is: the appropriate number, the appropriate wall thickness thin, height should be short, have enough slope, reinforced the bottom of the appropriate assumes the circular arc transition, should be to strengthen the direction and the material flow in the same direction in order to improve the toughness of the plastic;
2.
to improve the shape: box container for the rectangular thin-wall parts, more easy to deformation, various enhancement measures should be taken, the container four side slightly convex outward, in order to improve the stiffness; Is in the wall to prevent distortion belt reinforcement; On the edge of the container to prevent deformation of the mouth edge enhancement; At the bottom of the container designed to corrugated, the bottom of the arch and enhanced.
3.
the reasonable supporting: box describe the bottom area is larger, but the whole floor as a supporting is not reasonable, because of the slight arch at the bottom of the curve is put out, so the face should be bearing a line or point supporting, flange bearing ( The line bearing) ; Bump at the bottom of the foot bearing ( The point supported) ; The height of the bumps is commonly 0. 3 to 0. 5mm。
4.
Angle: the Angle of two or three of the handover, no matter what the shape of the container, all surface intersection place must use the rounded transition, this can greatly improve the stiffness of the container, at the same time can improve the charge model of plastic, and can disperse stress, reduce the deformation.
3. Container draft
to facilitate the mold release, in the design of the container must be considered when design the appropriate draft. Draft is too small, demoulding difficulty, damage container surface; Then affects the container size accuracy too.
draft due to the shape of the plastic parts, plastic, mould structure, surface roughness, the kinds of forming methods vary. In general, plastic pieces of commonly used slope along the parting direction for DHS ~ 1. 5 DHS, minimum not less than 0. 5º。
1. Injection products of wall thickness
of wall thickness are considered in the design of the three aspects: one is the thickness. Second, the uniformity; Three is a smooth transition.
1.
: the thickness of wall thickness of the main product is decided by its purpose, plastic types, structure, etc. For thermoplastic, usually should not be less than 0. 6 mm, often choose 2 ~ 4 mm; For thermosetting plastics, because of its liquidity is poorer, the thickness of the bigger, small to 1. 6 to 2. 5 ram, big 3. 2 ~ 8 mm, maximum of no more than 10 mm.
2) uniformity: the uniformity of wall thickness had a great influence on the quality of the container, a container if the thickness difference is too big, can make the uneven contraction, deformation, cracks and other defects. Therefore, in the structure design should be as far as possible when using thickness structure.
3. Gentle transition: in some containers, thickness of some parts due to the structure need to must not at the same time, such as container turning point, when the smooth transition should be adopted to avoid cross section mutation.
2. Improve the injection molding container stiffness
plastic is more flexible, containers made of stiffness is poorer, and turnover box class container capacity and large, sometimes in should take various measures to improve rigidity of the structure.
1.
add reinforcement, reinforcement can improve the strength and stiffness of the vessel. Basic requirements of stiffener is: the appropriate number, the appropriate wall thickness thin, height should be short, have enough slope, reinforced the bottom of the appropriate assumes the circular arc transition, should be to strengthen the direction and the material flow in the same direction in order to improve the toughness of the plastic;
2.
to improve the shape: box container for the rectangular thin-wall parts, more easy to deformation, various enhancement measures should be taken, the container four side slightly convex outward, in order to improve the stiffness; Is in the wall to prevent distortion belt reinforcement; On the edge of the container to prevent deformation of the mouth edge enhancement; At the bottom of the container designed to corrugated, the bottom of the arch and enhanced.
3.
the reasonable supporting: box describe the bottom area is larger, but the whole floor as a supporting is not reasonable, because of the slight arch at the bottom of the curve is put out, so the face should be bearing a line or point supporting, flange bearing ( The line bearing) ; Bump at the bottom of the foot bearing ( The point supported) ; The height of the bumps is commonly 0. 3 to 0. 5mm。
4.
Angle: the Angle of two or three of the handover, no matter what the shape of the container, all surface intersection place must use the rounded transition, this can greatly improve the stiffness of the container, at the same time can improve the charge model of plastic, and can disperse stress, reduce the deformation.
3. Container draft
to facilitate the mold release, in the design of the container must be considered when design the appropriate draft. Draft is too small, demoulding difficulty, damage container surface; Then affects the container size accuracy too.
draft due to the shape of the plastic parts, plastic, mould structure, surface roughness, the kinds of forming methods vary. In general, plastic pieces of commonly used slope along the parting direction for DHS ~ 1. 5 DHS, minimum not less than 0. 5º。
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