The structure of the core design

Molding parts work size refers to the direct type used to constitute the plastic parts surface size, such as radial size of injection mold cavity and core, the depth and height, the distance between the hole size, hole size or distance from the surface to a convex shape size, thread forming parts of radial size and pitch size etc. There are many factors affected the accuracy of injection molding product size, in a nutshell, a plastic material, plastic parts structure and forming process, die structure, die manufacturing and assembly, die in use factors such as wear and tear, and the plastic material factors is mainly refers to the influence of shrinkage. In the mould design should be based on material, geometry and dimensional accuracy level and influencing factors of design calculation, etc.

the inner surface of molding plastics parts according to punch or cores, core, thread core and ring etc. For the simple structure of the container, such as shell, hood, cap and plastic parts, forming the main body part of the inner surface of parts according to the main core or punch, and other core holes for molding or forming small core rod. The main core of the structure can be divided into integral and modular two. To facilitate the processing, the shape complexity is often used with modular structure.

used for molding plastic pieces of the screw hole of the screw thread core must be considered in the design of plastic shrinkage rate, the surface roughness is smaller, generally should be 0. 5° The draft, thread begin and end in accordance with the requirements of plastic thread structure design, in order to prevent from unscrew the roughcast plastic parts plastic thread. Fixed nut screw thread core don't have to consider when designing shrinkage rate, according to the common thread can be made. Threaded core is installed on the mold, forming the reliable positioning, cannot move due to vibration clamping or material flow impact, with plastic mould should be removed and is convenient for loading and unloading.

set spell combined the advantages and disadvantages of the advantages and disadvantages of core and combination concave die are basically the same. Design and manufacture of this type core, must pay attention to the structure is reasonable, should guarantee the strength of the core and the edge, to prevent the heat treatment deformation and should avoid sharp corners and wall thickness. Should be paid attention to when designing the core structure, plastic flash flash should not affect the demoulding of pick-up. Small core is used for molding plastic pieces of the holes or slots. Small core is made separately, and then embedded in the template.

for special-shaped mold core, in order to make convenient, often core design into two paragraphs. Core made round, the connection of the fixed period of connected by shoulder and templates. More close to each other in the small core, with shoulder when, if the shoulder overlapping interference can be shoulder touching one another so as to avoid grinding, the steps of the core fixed board hole processed into great circle bore steps or long waist rounded the steps, then the core insert.

using combined die, can simplify the complex die processing technology, reduce heat treatment distortion, split have clearance to exhaust, facilitate mold maintenance, saving valuable die steel. In order to ensure the accuracy of combination after the cavity size and assembly, reduce inlay spelling trace on the injection molding processing, the size of the set piece, shape tolerance level is higher, composite structure must be strong, set piece of machinery processing manufaturability is better. Therefore, it is very important to select the reasonable structure of combination with spelling.

thread core and ring are respectively used for molding plastic pieces of the internal thread and the activities of the external thread insert. In addition, the threaded core and the thread type ring also can be used to fixed threaded hole and the screw insert. After forming, the threaded core and the thread type ring measures method has two kinds, one is a mould automatic measures, the other is a mold manual measures. Thread core is divided into direct molding plastic pieces of the threaded hole according to the use and fixed nut insert two, these two kinds of screw thread core there is no difference in principle on the structure.

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