Post-vulcanization Treatment Of Rubber Products
After the vulcanization is completed, the rubber products often need some post-treatment to become a qualified finished product. This includes: 1 the trimming of the rubber mold products, so that the surface of the product is smooth and the dimensions are up to the requirements; 2 after some special processing, such as processing the surface of the product, the performance of the special-purpose products is improved; Articles containing fabric skeletons such as tapes, tires, etc. are subjected to hot stretching cooling and vulcanization and then cooled under inflation pressure to ensure product size, shape stability and good performance.
1. Trimming of mold products after vulcanization
When the rubber mold product is vulcanized, the rubber compound will continue to flow out along the parting surface of the mold to form an overflow rubber edge, also known as a flash or flash edge. The thickness and thickness of the rubber edge are determined by the structure and precision of the mold. The parallelism of the flat vulcanizer plate and the amount of glue remaining. Nowadays, the products produced by the infinite mold have a very thin rubber edge, and sometimes they can be removed or gently rubbed off when the mold is released. However, such molds are costly and fragile, and most rubber molded articles require trimming after vulcanization.
Manual trimming is an ancient method of trimming. It involves manually punching the edges with a punch; removing the edges with scissors, scraping and other tools. The quality and speed of hand-trimmed rubber products will vary from person to person and require trimming
The geometry of the finished product must conform to the product drawing requirements and must not be scratched, scratched or deformed. Before trimming, it is necessary to clearly understand the trimming parts and technical requirements, master the correct dressing method and use the tools correctly.
2. Mechanical dressing
Mechanical dressing refers to the process of trimming & 5 of rubber mold products using various special machines and corresponding process methods. It is currently a more advanced finishing method.
(1) Mechanical punching and trimming The rubber edge of the product is removed by means of a press machine and a die and a punching knife. This method is suitable for articles and molded articles whose glue edges can be placed on the die or the punching plate, such as stoppers, cups, and the like. For products with high gel content and low hardness, the impact method is generally used to impact the trimming edge. This can reduce the unevenness of the edge after the knife cutting due to the large elasticity of the product, and the side surface is concave; and the rubber content is lower and the hardness is higher. The product can be directly cut by the knife die method. In addition, die cutting is also divided into cold cutting and hot cutting. Cold cutting refers to punching at room temperature. The punching pressure of the equipment is required to be higher, and the quality of the punching is better; the hot cutting refers to the higher temperature -f, When cutting, it should prevent the high temperature from contacting the product for too long and affect the product quality.
(2) Mechanical cutting and trimming is suitable for trimming of larger-sized products, using cutting tools. A side cutting machine is a special machine, and different products use different cutters. For example, after the tire is vulcanized, there are strips of different lengths on the surface of the gas eye and the vent line, and the strip must be removed using the grooved tool under the condition of the tire rotating.
(3) Mechanical grinding and trimming For mold rubber products with inner and outer rings, grinding is usually used. The grinding blade is a grinding wheel with a certain thickness of the particles. The precision of grinding and trimming is low, and the grinding surface is rough. It may have residual sand particles, which may affect the use effect.
(4) Low temperature shot blasting For fine products with high trimming quality requirements, such as 0-rings, small cups, etc., this method can be used for trimming. The product is rapidly cooled to below the brittle temperature with liquid nitrogen or dry ice, and then the metal shot or plastic projectile is sprayed at a high speed to break the edge of the flash and complete the trimming.
(5) Low-temperature brushing and trimming It removes the rubber edge of the frozen rubber product by means of two nylon brushes rotating around a horizontal axis.
(6) Low-temperature drum trimming It is the earliest adopted method of freezing trimming. The impact force generated by the rotation of the drum and the friction between the products are used to break and fall off the edge of the product that has been frozen to below the embrittlement temperature. The shape of the drum is generally octagonal to increase the impact force of the product in the drum, the rotation speed of the drum should be moderate, and the addition of the abrasive can improve the efficiency. For example, the trimming process of the rubber plug of the electrolytic capacitor is to use a low temperature drum to trim.
(7) Low-temperature vibration trimming, also known as vibration freezing trimming, the product is spirally vibrated in the ring-shaped sealed box, and there is a strong impact between the products and between the product and the abrasive, causing the frozen embrittlement drop. The low-temperature vibration trimming is better than the low-temperature drum trimming, the product damage rate is low, and the production efficiency is relatively low.
(8) Low-temperature swinging and dither trimming are suitable for small or micro-products or micro-rubber products containing metal skeletons. Together with the abrasive, the rubber edges in the product holes, corners and grooves are repaired.
Haining Qianlang Rubber Products Factory
ADD: NO.10-2, Lianbao Road, Qianjiang Industrial Park, Dingqiao Town, Haining, Zhejiang 314413, China