When the mold is vulcanized, the rubber will flow out along the parting surface and other parts of the mold, forming overflow rubber edges, also known as burrs or flash. The number and thickness of rubber edges depend on the structure and precision of the mold, the parallelism of the plate of the plate vulcanizer, and the amount of residual rubber. The rubber edge of the products produced by the current borderless mold is particularly thin, and sometimes it can be removed by taking off the mold or gently wiping. However, this kind of mold has high cost and is easy to damage. Most mold products need to be repaired after vulcanization.
1. Manual finishing
Manual trimming is an ancient trimming method, which includes manually punching the rubber edge with a punch; Use scissors, scrapers and other tools to remove the glue edge. The quality and speed of manually trimmed products will also vary from person to person. It is required that the geometric dimensions of the trimmed products must meet the requirements of the product drawings without scratches, scratches and deformation. Before trimming, the trimming parts and technical requirements must be clear, and correct trimming methods and tools must be mastered.
2. Mechanical finishing
Mechanical trimming refers to the process of trimming die products with various special machines and corresponding process methods. It is an advanced trimming method at present.
(1) Mechanical punching trimming removes the glue edge of products with the help of pressure machine, punching die and punching knife. This method is applicable to products and model products whose rubber edges can be placed on the bottom plate of the punching die or punching knife, such as bottle stoppers, leather cups, etc. For products with high glue content and low hardness, the impact cutting method is generally used to cut the edges, which can reduce the uneven edges and side dents caused by the large elasticity of the products after cutting; For products with lower glue content and higher hardness, the knife edge die can be directly used for punching. In addition, punching can also be divided into cold cutting and hot cutting. Cold cutting refers to punching under room temperature, which requires high punching pressure of equipment and good punching quality; Hot cutting refers to cutting at a high temperature - f. During punching, it is necessary to prevent high temperature from contacting products for too long, which will affect product quality.
(2) Mechanical cutting trimming is applicable to trimming of products with large overall dimensions, and cutting tools are used. All cutting machines on one side are special machines, and different products use different cutters. For example, if there are rubber strips with different lengths at the air hole and exhaust line of the tire after vulcanization, the rubber strips must be cut off with grooved tools under the condition of tire rotation.
(3) For die pneumatic butterfly valve with inner hole and outer circle, grinding square is usually used for mechanical grinding trimming. The cutting tool to be ground is a grinding wheel with certain particle size. The precision of grinding trimming is low, and the grinding surface is rough, which may contain residual sand particles, affecting the use effect.