The specific process flow of rubber skeleton oil seal production is as follows: rubber preparation section, mold preparation section, skeleton preparation section; spring preparation section, product vulcanization molding section, and post processing assembly section. Therefore, the process flow is basically composed.

In the production of seals, most of them are manual labor and increase the cost of the two main processes: 1, vulcanization; 2, inspection.

1. Rubber preparation section

The main processes of this section are as follows:

According to the above procedures, raw materials can be mixed after passing the factory inspection. Open mixer or internal mixer can be selected according to production needs. Generally, the rubber mixture should be filtered. In order to prevent the rubber from scorching, the vulcanizing agent is added after the rubber is filtered, which is called two-stage mixing. In fact, some manufacturers use one-stage mixing method in production. All the ingredients are added before filtration. The process conditions are controlled during filtration or the scorching is considered in the formula. This method also has some advantages, such as simplifying the process and reducing the possibility of secondary pollution. It should be emphasized that the rubber material inspection is an important process in the oil seal production process, and it is also one of the main means to control the oil seal quality. In addition, the rubber preform is also the key process of oil seal production process. The traditional process is to prepare the rubber compound into a certain thickness film in the open mill, and then cut into semi-finished products with certain shape and weight according to the requirements. At present, professional oil seal manufacturers are using precision preformer direct molding machine. Compared with the traditional method, this method is more efficient and precise in shape and weight control of semi-finished products

2. Mold preparation section

Oil seal mold and other rubber seal mold processing, processing process is the same. Usually, the blank should be forged to eliminate the internal stress, then quenching and tempering, heat treatment, and sometimes the die cavity surface treatment is required. Such as surface nitriding or hard chromium plating.

3. Skeleton preparation section

The skeleton preparation section includes skeleton stamping and skeleton surface treatment. Skeleton stamping generally adopts one-time stamping, while external framework and combined framework need multi-stage stamping, and sometimes need finishing treatment.

The surface treatment of the framework is mainly to make the metal framework and rubber well bonded. The common methods are as follows:

① Degreasing (alkali treatment) - dry sand blasting - Cleaning - drying - gluing agent;

② Wet sand blasting - Cleaning - drying - gluing adhesive;

③ Degreasing and degreasing - Pickling - phosphating - gluing adhesive.

Traditional process is step-by-step intermittent operation, except for sandblasting machine, other equipment are non-standard equipment. In recent years, many domestic manufacturers have set up continuous production lines for skeleton treatment, such as wet sand blasting device, pickling and phosphating production line. Degreasing agent, phosphating agent, pickling solution and adhesive used in the surface treatment of skeleton are sold in China, and can be purchased directly according to the needs.

4. Spring preparation section

The oil seal spring is made by winding the steel wire on the spring winding machine. The deformation of the spring steel wire is different when the cross section is in different positions in the winding state. The external tension and internal pressure mouth of the spring steel wire means that there is a certain deformation stress in the steel wire, resulting in the instability of the spring size and large elastic difference. Therefore, the wound spring needs heat treatment. The method of heat treatment is to heat and soak the wound spring in oil (antirust oil or cylinder oil, etc.) and make stress tempering and antirust treatment port

5. Product vulcanization molding section

Frame oil seal vulcanizing equipment usually includes ordinary plate curing press, vacuum automatic plate curing machine, rubber injection press and so on. The vulcanization molding conditions in actual production vary with product specifications and rubber compound. At present, the pursuit of the factory is to use high temperature and short time vulcanization molding process as far as possible under the premise of ensuring product quality.

6. Post processing and assembly section

The vulcanized oil seal needs to be trimmed, especially the lip of the oil seal is the key part to determine the performance and service life of the product. According to the structure of oil seal mold, the main lip often has several structures as shown in the figure below: full cutting lip (full cutting), local cutting lip (half cutting) and die pressing lip. The product of molding lip is realized by using flangeless die, and the product can be trimmed by tearing edge method. Full cut and half cut lip products need to be trimmed by trimming machine (incision machine). There are standard equipment for sale at home and abroad. The framework trimming and buckling of outer framework oil seal and combined oil seal are generally carried out on non special tooling equipment.