The use of rubber fender was first started in the United States in 1932, and it began to be used in bulk in Europe in the construction of oil terminals around 1950. After Japan started to use it in yokoshima in 1954, it began to be mass-produced in 1956. At present, there are several large rubber products factories in China producing rubber fenders, including common type and super large products.

As large chemical products, large rubber fender size scale is very large. At present, it still cannot choose in the conventional size range of forming vulcanizing machine and forming mold. It must choose large vulcanizing unit and open both heating and pressure characteristics of forming mold. The characteristics of rubber model products are determined by the properties of rubber materials, other tooling or equipment conditions and production methods. This project developed and designed a frame-type vulcanizing press with rubber fender structure, and manufactured a series of modular mold equipment system with characteristics, including the selection of heating system and control instrument.

1. Large high resistance rubber fender and its forming characteristics

 1.1 Features of large rubber products:

Compression type rubber fender can be subdivided into D type rubber fender, cylindrical rubber fender, arch rubber fender, cell rubber fender and I type rubber fender. D type rubber fender and cylindrical rubber fender are early varieties. Cell rubber fender is a new type developed for large ships in recent years. The characteristics of the cell rubber fender are the large size products, and in front of the rubber body are equipped with metal, plastic or wooden impingement plate. This kind of fender is widely used in wharf, pier wharf and other large wharf in open sea. Geometric features: Usually refers to a wide range of dimensions, ranging from 5 to 20 meters on at least one scale. Obviously such a large piece in the shape of the general requirements for size is not high, or not very fine. Molding characteristics: in fact, almost all rubber products achieve its molding processing through the corresponding mold. The function of the mold is not only to use the cavity of a particular shape to form a certain shape and control the dimensional accuracy, but also to transfer the forming pressure. For large rubber products, in addition to strip products, shaped section of various parts of the molding process must be implemented by the mold. Therefore, the low-cost molding process is often used. The second characteristic of large rubber parts forming is lengthening vulcanization, or cupping, which is also one of the significant differences between large rubber parts and ordinary parts in forming characteristics.

 1.2 Characteristics of large high resistance rubber fender

Due to the requirements of the performance, the main characteristics of the finished rubber fender are high quality and high density, the density of rubber parts is much higher than the density of ordinary rubber parts. If the density is not large enough, its elastic resistance or energy absorption capacity will not meet the requirements for use. Large fenders become more and more important to ensure rigidity with high density as the body increases. Although the formula plays a major role, the forming pressure is an important means of forming large density.

2. Requirements of rubber fender molding and vulcanization system

The characteristic of large rubber fender determines that the vulcanizing forming of rubber fender will put forward its own characteristic requirements to the forming vulcanizing machine or vulcanizing equipment including pressure system, mold system, heating system and control system. Ordinary vulcanizing machine cannot achieve the pressure system formed in the large load. We use the frame type large flat with plate vulcanizing machine frame structure as the foundation to produce a large load, large length press and pressure control hydraulic system through the improved design. The mould system not only restricts the formation of shape, but also ensures the requirement of curing temperature by coupling design and manufacture with the heating system. A lot of work is limited to space cannot be detailed here, as an example of the analysis of some mold aspects of the problem.

 2.1 Structural requirements for molds and vulcanization systems

Rubber mold is one of the most important equipment for vulcanization of rubber products. The mould design is based on the shape, characteristics and requirements of the products. The reasonable choice of mold structure is directly related to the quality of products, production efficiency, difficulty and service life of mold. The general principles to be followed are: to master and understand the hardness, shrinkage and use requirements of the materials used in rubber products. The mold has reasonable structure, reliable positioning, convenient operation and safe use. The number of mold cavities should be appropriate to facilitate machining and mold use, and the production efficiency should be taken into account. The die should have sufficient stiffness and strength to minimize weight and simplify shape. The mold cavity should be easy to charge, exhaust and spare materials when used. The rubber material should have enough pressure when vulcanized. Mold design should conform to the series, standardization, and strive to be universal. In addition to following the general principles of rubber mold, there are obviously some special requirements for the mold equipment of large rubber fenders. Unlike small solid structure mold, this large mold structure design is focused on reducing weight. The physical structure not only consumes the material for mold making and increases the cost, but also the excessive size makes the weight too large, which may make the convenient operation impossible and only increase the high-cost auxiliary tools, thus increasing the product cost. Through the research, it is concluded that the steel plate composite structure is a good choice of structural form.

The combined mold defined in this design is not the same as the traditional combined rubber mold. The traditional combination mold concept is based on the solid mold foundation, its structure form characteristic is can change each pair of single core conveniently, may combine each kind of product spare parts production at any time. Also according to the specification of the parts of the products, the replacements of all the mold core, or composite parts of the mold core, adjust the various parts in the production of the number of parts. And the large steel structure modular mold we developed is similar to the concept of panel furniture. On the basis of the various combination templates produced, the large tooling equipment system is assembled.

2.2 The technological requirements of rubber mold system design

The technological requirement of die design means that the designed die or molding equipment should meet the requirements of the whole molding process of rubber parts. In addition to the determination of the basic large structure form, in order to better meet the requirements of manufacturing quality and the precise realization of various technological parameters of the molding process. There are some requirements for the manufacturability of the mold, including the determination of mold cavity and its dimensional accuracy, surface finish or roughness, technology selection and machinability of parting surface, mold positioning mechanism, residual material trough and mold opening trough and process hole and other elements.

The selection of parting surface is generally based on the section geometry of fender. There are two cases, or the bottom or the middle section of the symmetrical plane as the basic parting surface. The selection of parting surface is one of the most important links in mold design, which directly affects the processing efficiency, using state and quality of molded rubber fender products. In the selection principle of parting surface, for large fender molding, the large load and high pressure during molding may make it difficult to take out the parts, so easy to take out the parts should be considered. In practice, the rationality of parting surface should be analyzed from the whole process of molding process.

3. Conclusion

Through design, manufacture and use, it is shown that the development of large rubber fender manufacturing equipment from structural design to process design and manufacture is not covered by the design principles and rules of ordinary rubber vulcanizer. Large size, large density or large weight of the special point, determine the structure of the first to consider how to reduce the weight of manufacturing equipment. It mainly reflected in the mold design, manufacturing and use. Secondly, the characteristics of the vulcanization heating system are reflected in the selection and control of the vulcanization process parameters, namely pressure, time and temperature, as well as the reasonable design of the thermal energy supply system. Using electric heat pipe to heat with electric energy can be convenient to use, but it is still possible to improve the structure of the heating system and further save electric energy and reduce the cost. From the existing public information, there are few about large rubber fender vulcanizing machine series, specialized production report, let alone or standardized work. With the development of shipping industry and water conservancy engineering at home and abroad, large-scale specialized rubber fender products are widely used, this aspect of work and research is extremely broad prospects in the industry.