I. Compression molding

Compression molding is commonly used to make some rubber products with complicated shapes such as leather bowls and seals. The rubber material is placed in the mold and heated to form by using the female and male molds.

Second, extrusion molding

Extrusion molding is also called extrusion molding. The common equipment for extrusion molding is a rubber extruder, which works similarly to a plastic extruder. The material enters the barrel through the hopper of the extruder. Through the action between the barrel and the rotating screw, the rubber is heated and plasticized while being pushed forward by the screw. It is continuously passed through the machine head and made with a die. Products or semi-products with complex cross-sectional shapes, such as tire tread rubber, inner tube, tube, pure rubber tube, inner and outer rubber of rubber tube, and outer sheath of wires and cables.

It is used for more complex rubber products, such as tire treads, hoses, and wire surface rubber coating, which need to be manufactured by injection molding.

It is a method of putting the compounded rubber with certain plasticity into the hopper of the extruder and extruding it through the various types of mouths, also called templates, under the extrusion of the screw.

Before extrusion, the rubber compound must be preheated to make the rubber soft and easy to squeeze out to obtain a rubber product with a smooth surface and accurate size.

Three, injection molding

Injection molding of rubber is a production method of injecting the mixed slurry directly into the mold vulcanization through the feeding device, similar to plastic injection molding. Using injection molding, the molding cycle is short, the production efficiency is high, the labor intensity is small, and the product quality is high. Mainly used in the production of seals, vibration pads and footwear.

The rubber injection molding process includes feeding, plasticizing, injection, holding pressure, vulcanization, and mold release. Six-mold rubber shoe injection machine molding schematic diagram, first the pre-mixed rubber material is sent to the barrel through the hopper. Under the action of the screw rotation, the rubber material is pushed along the spiral groove to the front of the barrel. Due to the intense stirring and deformation, and the external heating of the barrel, the temperature quickly rises and the plasticity increases. When the rubber reaches the front of the barrel, the injection cylinder moves forward so that the nozzle at the front of the barrel contacts the gate of the model. Then the injection cylinder injects the glue. The glue is injected into the mold cavity through the nozzle and is held for a period of time. During the holding process, the rubber is vulcanized at a high temperature until the mold is ejected. Go on.

Injection molding has significant advantages:

①Simplify the process and reduce the number of operators;

② Reduce energy consumption by about 10%;

③Improve production efficiency by 4-7 times;

④Improve the uniformity, stability, dimensional accuracy and qualification rate of products;

⑤Reduce flash and save rubber;

⑥ Easy to operate, low labor intensity, high degree of mechanization and automation. Therefore, in recent years, injection molding technology has received more and more important attention, and has developed rapidly in the production of rubber products.

Four, calendering

Rolling is the process of subjecting materials to stretching. The main equipment for calendering is a three-roll or four-roll calender. The three-roll calender is realized by the pressure of the rotating two rolls. When the rubber material passes through the gap between the rollers, the rubber strip is stretched into a certain cross-sectional shape under pressure, or the process of hanging glue on the fabric is realized. It is generally used for rubber sheet pressing, molding, textile, steel wire cloth, etc. sticking, wiping, and the bonding of film and film, film and hanging fabric.

Suitable for making simple sheet and plate products. It is a method of pressing the compounded rubber into a film with a certain thickness and a width through a calender, which is called calendering.

Some rubber products such as tires, tapes, hoses and other textile fiber materials must be coated with a thin layer of glue on the fibers, also called glue or rubbing, the coating process is generally completed on the calender.

The fiber material needs to be dried and dipped before drying. The purpose is to reduce the water content of the fiber material, to prevent the water from evaporating and foaming, and to increase the temperature of the fiber material to ensure the quality of the calendering process.

Dip is a necessary process before hanging glue, the purpose is to improve the binding performance of fiber material and rubber material.

The calendering process includes the following basic steps: preheating and supplying rubber compounding; opening and drying of textiles (and sometimes dipping); pressing of rubber on a four-roller or three-roller calender or Hanging glue on textiles and cooling, curling, cutting, placing of rolled semi-finished products.

Before calendering, the rubber and textiles need to be pre-processed. Before the rubber enters the calender, it is first pulverized on a hot refining machine. This process is called hot refining or preheating. The purpose is Improve the uniformity of rubber compounding, further increase the plasticity, increase the temperature, and increase the plasticity. In order to improve the adhesive properties of rubber and textiles and ensure the quality of calendering, the textiles need to be dried. The moisture content is controlled between 1% and 2%. The moisture content is too low, the textile becomes hard, and the fabric is easily damaged during calendering. Too high, its adhesion is poor.