When it comes to sealing strip, we will think of the application of sealing strip in car doors, Windows, bodies, seats, sunroofs, engine cases and trunk and its waterproof, sealing, sound insulation, dust, anti-freeze, shock absorption and other functions, because the sealing strip application is equipped in different parts of the car, with different uses and functions, so the structure of the mold is more complex. Heideparker has prepared relevant knowledge about rubber extrusion mold structure and mold design, let us have a general understanding of it.
Rubber seal extrusion features
First, in order to better understand the knowledge of rubber extrusion mold, let's familiarize ourselves with the characteristics of rubber extrusion.
(1) The rubber material is further mixed and plasticized through the rotation of the extruder screw to ensure that the quality of the extruded semi-finished rubber material is more dense and uniform;
(2) Wide application, by changing the mouth mold, you can extrude various section shapes of rubber profiles and pre-formed semi-finished products for pressing molds;
(3) extrusion products have high speed and high production efficiency, which is conducive to automated production;
(4) Extrusion molding is not limited by length, and can produce ultra-long products that cannot be molded.
Second, rubber seal extrusion mold design precautions
Mold design commonly used design software AutoCAD, Pro/E, UG, CATIA SolidWorks, etc., because the sealing strip extrusion products are not limited by length; And the type of seal not only contains monomer rubber seal (pure rubber seal), but also contains complex rubber seal (metal support skeleton composite seal); In addition, the sealing strip in the installation and use process, will show very complex mechanical properties, such as material properties, geometric nonlinearity, boundary condition nonlinearity, so the sealing strip molding process is very precise and complex, so in the mold design should pay attention to the shrinkage of different materials rubber, as well as product layout and internal structure.
Single rubber extrusion mold design precautions:
For any extrusion die, the design point is to ensure that the extrusion section size and shape of the composite design requirements. Therefore, the following six factors need to be considered in the design of single rubber extrusion mold:
(1) When any rubber material is extruded from the extrusion mold, different expansion will occur. When the hardness of the rubber material is small to large, the expansion rate of the extrusion section is large to small;
(2) When the extruder temperature changes from low to high, the extrusion section expansion rate changes from small to large;
(3) When the extrusion speed changes from low to high, the extrusion product section only changes from small to large;
(4) Different kinds of rubber or mixed rubber with different rubber content, the expansion rate of the extrusion product section is different;
(5) The expansion rate of each part of the section of any extruded product is not to pass, especially the opposite sex section;
(6) The design shape of the extrusion die will have different effects on the section and size of the extrusion product.
Complex rubber extrusion mold design precautions:
In addition to the design of the complex rubber extrusion mold with the design of a single rubber extrusion mold, there are some special requirements
(1) It is necessary to ensure that the extrusion speed of different types of rubber (and skeleton) is consistent with each other to ensure that different types of rubber (and skeleton) can be well combined into a whole;
(2) For composite extrusion molds with skeleton (metal or wire braid), it is necessary to ensure that the locking of the composite position between the skeleton leading-in mold and the extrusion mouth mold and whether the locking design of adjusting the composite gap is reasonable;
(3) The inclination Angle of the cavity of the skeleton importing die and the composite extrusion die in the composite extrusion die should be appropriate.
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