Rubber suction cups require some process after vulcanization molding, so that it can become a qualified finished product. This includes:
1 Trimmed: to make the surface of the suction cup smooth and the outer dimensions meet the requirements.
2 Special processing: such as using some special pricess on the surface of the suction cup, to made the performance of the special-purpose products improved;
3 The suction cup product containing the fabric skeleton needs to do the hot stretching cooling and cooled under inflation pressure after vulcanization,to ensure the product size, shape stability and good performance.
- Triming of the suction cup mold after vulcanization
When the rubber suction cup is vulcanized, the rubber material will flow out along the parting surface of the mold to form an overflow burr, we also call it burr or flash. The thickness and size of the burr are determined by the structure, precision and the parallelism of the machine plate mold and the amount of glue remaining. The edge of the suction cup produced by the current infinite mold is particularly thin, and sometimes it can be removed directly when it is taken out of the mold, or just gently wiped off. However, this kind of molds are costly and vulnerable. Most rubber suction cups require trimming after vulcanization.
There are several ways to trim,
- Manual trimming method: manual punching, scraping, boring, cutting, scraping,
- Normal temperature mechanical triming: punching, cutting, grinding
- Low temperature mechanical triming method: shot blasting, drum trimming, vibration trimming, shaking, swing trimming, brush trimming, centrifugal impeller blasting
Manual trimming is an ancient method of trimming, which involves manually punching the burrs with a punch; removing the burrs with scissors, scrapers, etc. The quality and speed of manual trimming are depends on people. The geometry of the finished product must conform to the product drawing requirements and must not be scratched, scratched or deformed. Before trimming, you must know the trimming position,technical requirements, the correct trimming method and how to use the tools.
- Mechanical trimming
Mechanical trimming refers to the process of trimming rubber suction cup products by using various special machines and corresponding process methods. It is currently a more advanced method of trimming.
(1) Mechanical punching and trimming remove the burr of the suction cup by using a pressure machine and a die punching knife. This method is suitable for the suction cups which burr can be placed on a die punching plate. This method is generally used for the suction cup with high gel content and low hardness.This can reduce the unevenness of the edge after the knife cutting and the side surface depression due to the large elasticity of the product;
As for the lower rubber content with higher hardness. The product can be directly cut by the knife die method. In addition, die cutting also have two method, cold cutting and hot cutting. Cold cutting refers to punching at room temperature. It will need the equipment with higher die cut pressure, and the quality of punching is better. Hot cutting refers to punching at a higher temperature. It should prevent the high temperature from contacting the product for too long which will affect the product quality.
(2) Mechanical cutting and trimming is suitable for the trimming of larger-sized products, using cutting tools. General cutting machines are special machines, and different products use different cutters. For example, after the tire is vulcanized, there got some strips in different lengths on the surface of the exhaust eyes and the exhaust line. The strip must be removed by using a grooved tool under the condition of tire rotation.
(3) Mechanical grinding and trimming For suction cups 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, the grinding surface is rough and there may be residual sand particles, which affects the use effect.
(4) Low temperature shot peening are generally used for the high quality small suction cup. The product is rapidly cooled to below the brittle temperature with liquid nitrogen or dry ice, and then the metal projectile or plastic projectile sprayed into at high speed to break the flash and remove the trimming.
(5) Low temperature brushing and trimming, which removes the burrs of the frozen suction cup by means of two nylon brushes rotating around a horizontal axis.
(6) Low temperature drum trimming which is the earliest adopting the 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 which has been frozen to below the embrittlement temperature. The shape of the drum is generally in octagonal, that will increase the impact force 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 should use this low temperature drum to trim.
(7) Low-temperature vibration trimming, also known as vibration freezing and trimming, the products are spirally vibrated in a circular sealed box, and there is a strong impact by abrasive between the products, which causing the frozen embrittlement broken. The low-temperature vibration trimming is better than the low-temperature drum trimming, its product damage rate is low.
(8) Low-temperature swinging and shaking trimming are suitable for small,micro-products and products that containing metal bamboo frames. It can be used with the abrasive to removed the edges, corners, burrs in the grooves of the product.