The rubber compound is manually filled into the mold cavity, and after the mold is closed, it is suitable to press and heat the vulcanizer to form and vulcanize the rubber compound in the mold cavity to obtain a rubber molded product, which is called press molding. law. The process flow of this production method can be divided into the following production stages.
1In the production preparation stage, in the production process of rubber moldings, the design requirements of the rubber or semi-finished products (ie, preformed but not vulcanized intermediate products) are loaded into the mold cavity, and the required rubber compound formula is selected. The mixer is kneaded to become a certain thickness of the sheet material required for the molding of the rubber; then it is manually cut into suitable squares, strips, discs or shaped blocks to fit the mold cavity. Pre-formed (or precision pre-formed) of the pre-vulcanized semi-finished product can be molded by various types of molding machines, if available.
Special pre-forming processing equipment can be divided into precision pre-forming machines, general pre-forming machines, rounding machines, slitting machines, punching machines, drilling machine-type circular knitting machines, and extrusion machines according to their functions. Preform processing of the compound, especially precision preforming, not only improves production efficiency, but also facilitates semi-automated production.
If the preparation before the mold is carried out by manual operation, the result will be time-consuming labor, low utilization of the rubber material, thick flash around the product, and the dimensional accuracy of the product parts will not be improved.
If the insert part is included in the shape of the product part, the insert needs to be processed before entering the mold.
2 Molding vulcanization stage rubber or rubber semi-finished products (including the inserts required for the product) After being loaded into the mold cavity, molding and vulcanization are carried out under the conditions of pressure, temperature and time, and then the mold is applied. The production process of taking out the parts from the cavity is called the molding vulcanization stage. For some rubber parts, according to the requirements of the production process, two-stage vulcanization is also required. The purpose is to shorten the vulcanization time of the rubber in the mold cavity and improve the utilization rate of the mold and vulcanizer. The second stage of vulcanization is carried out by concentrating the parts of the product after compression molding (i.e., one stage of vulcanization) in an oven or a vulcanization tank to improve production efficiency.
3 Clearing the flashing stage To remove the flashing edge, the rubber edge (or film) formed by the product part along the mold parting surface is removed, so that the appearance of the product part can meet the requirements.
4 Quality inspection stage The ultimate goal of the whole process of production is to obtain rubber moldings that meet the design requirements and are satisfactory to the users. The process of judging whether a part of a product is qualified is called the inspection stage of the product, that is, the quality inspection stage. The quality inspection of products can be divided into random sampling inspection and final batch inspection. Random sampling inspection aims to timely discover the quality problems existing in the production process, identify the causes, adjust relevant process factors in time, and ensure the quality of product parts. The final batch inspection is aimed at the quality assessment of the products that have been pressed and the elimination of scrap and defective products. Both of these tests are very important.