After vulcanization, rubber products often need some post-treatment to become qualified products. This includes: (1) trimming the rubber mold products to make the surface of the products smooth and meet the requirements; 2 After some special processing, such as surface treatment, the service performance of products for special purposes is improved; ③ for products containing fabric skeleton, such as rubber belt and tire, the products should be cooled under inflation pressure after hot stretching cooling and vulcanization, so as to ensure the product size, shape stability and good performance.

1、 Dressing of mould products after vulcanization

When rubber mold products are vulcanized, the rubber compound will flow out along the parting surface of the mold, forming overflow rubber edge, also known as burr or flash edge. The number and thickness of rubber edge depend on the structure and precision of the mold, the parallelism of the flat plate of the plate curing machine and the amount of residual rubber. The edge of the products produced by the present boundless mould is very thin, sometimes it can be taken off when the mold is lifted or it can be removed by wiping it lightly. However, the cost of this kind of mold is high and easy to be damaged. Most rubber moulded products need to be trimmed after vulcanization.

1. Manual finishing

Manual trimming is an old trimming method, which includes punching rubber edge with punch manually and removing glue edge with scissors and scraping tools. The quality and speed of hand-operated rubber products will also vary from person to person. It is required that the geometric dimensions of finished products must meet the requirements of product drawings, and there shall be no scratch, scratch and deformation. Before finishing, you must know the trimming position and technical requirements, master the correct trimming method and use tools correctly.

2. Mechanical finishing

Mechanical trimming refers to the trimming process of rubber mold products with various special machines and corresponding technological methods. It is an advanced dressing method at present.

(1) With the help of pressure machine, punching die and punching knife, the rubber edge of products can be removed. This method is suitable for products and model products whose rubber edges can be placed on the die or die plate, such as bottle stopper, leather cup, etc. For the products with small edge and high hardness, it is possible to reduce the impact on the edge of the products due to the higher hardness of the edge. In addition, punching is also divided into cold cutting and hot cutting. Cold cutting refers to punching under room temperature, which requires higher punching pressure and better punching quality; hot cutting refers to that when punching at high temperature - F, long time of high temperature contact with products shall be prevented from affecting product quality.

(2) Mechanical cutting edge trimming is suitable for trimming of products with larger dimensions, using cutting tools. One side cutting machinery is a special machine, different products use different cutters. For example, there are rubber strips of different length on the air hole and exhaust line on the surface of the tire after vulcanization, and the rubber strips must be cut off with a grooved tool under the condition of tire rotation.

(3) For the rubber products with inner hole and outer circle, grinding square is usually used. The grinding tool is a grinding wheel with a certain particle size. The precision of edge dressing is low and the grinding surface is rough. There may be residual sand particles in it, which will affect the use effect.

(4) Low temperature shot blasting trimming can be used for fine products with high trimming quality, such as 0-ring, small cup, etc. The product is quickly cooled to below brittle temperature with liquid nitrogen or dry ice, and then metal or plastic shot is sprayed at high speed to break and fall off the flash edge to complete trimming.

(5) It uses two nylon brushes rotating around the horizontal axis to remove the rubber edge brush of frozen rubber products.

(6) Low temperature drum trimming is the earliest freezing trimming method. It uses the impact force generated by the rotation of the drum and the friction force between the products, so that the flash edge of the product which has been frozen to below the embrittlement temperature will break and fall off. The shape of the drum is generally octagonal to increase the impact force of the product in the drum. The rotational speed of the drum should be moderate, and the efficiency can be improved by adding abrasives. Such as electrolytic capacitor rubber plug trimming process is the use of low temperature drum trimming.

(7) Low temperature vibration trimming is also known as vibration and freezing trimming. When the products are vibrated spirally in the annular sealing box, there is a strong impact between the products and between the products and the abrasives, resulting in the crumbling of the frozen brittle rubber edges. Low temperature vibration trimming is better than low temperature drum trimming, with low damage rate and high production efficiency.

(8) Low temperature swing and shaking trimming is suitable for small or micro products or micro rubber products with metal framework. The rubber edges in holes, corners and grooves of products can be removed together with abrasives.