Special rubber seals - brief introduction of leather bowl

1) leather bowl commonly known as Ba Jin (leather ring), the same function with the oil seal, but also a lip bidirectional seal.
Mainly used for reciprocating piston pump, such as sealing, which can be used independently, but also can use multiple overlapping combination.
In addition to the preparation of high hardness rubber for the high pressure leather bowl, there is often a fiber cloth in the middle,
which is made into rubber cloth products. The leather bowl for contact type self sealing products, its shape is divided into various forms of V, U, Y, L, J,
thousands of species, widely used in equipment and hydraulic braking system, especially in the automotive, construction machinery and other aspects of security has become the key components.
2) at present, the temperature requirement for the leather bowl is between -45 and +260 degrees centigrade, and the working pressure is from 10 to 60MPa,
and the maximum is 1O0MPa. In reciprocating motion, the speed is 0.5-2.5m / s, and the service life is over N4oo ~ 500km.
For pneumatic leather bowl, due to the reciprocating motion mostly in low pressure, the reaction is low speed and sensitive,
especially when swinging operation, the starting pressure is often lower than 01MPa. Some instrument bowls, even at lower atmospheric pressure, should be sensitive and responsive.
3) leather bowl requires heat resistance, cold resistance, durability, brake resistance, hydraulic and precipitation resistance, etc.,
the conditions are relatively harsh. The choice of rubber material, usually at a temperature of -7O~+8O degrees Celsius,
mainly the use of natural rubber (NR) manufacturing. Requirements of heat resistance, wear resistance, turn over, hydraulic resistance a
nd operating temperature of -6O ~ +1O0 degrees Celsius, working conditions, using styrene butadiene rubber (SBR): temperature in the range of -6O~+130 degrees Celsius,
and more use of ethylene propylene rubber (EPDM). Now, the EPDM has become the dominant material for high-performance leather bowls. For more rigid ones,
the more desirable is poly (vinyl chloride rubber) (PUR). At present, improving the abrasion resistance of leather bowl is still an important subject to be improved.
4) the basic form of leather bowl is divided into two categories: dish type and cup type.
Previously mainly to dish based, most have now turned to good performance stability cup type. The sealing lip portion of the past for cutting,
and now have to action can reduce the resistance, dimensional stability and Du system type better seal lip mouth. For a long time,
the reliability of the sealing of the bowl has been confirmed by hydraulic oil, which has been used for a long time.
The disadvantage of this method is that on the one hand, it takes a long time to investigate; on the other hand, if there is a leak,
it is difficult to tell whether it is the structural shape or the rubber material, which causes it.
In recent years, the finite element method has been widely used to determine the optimum structure shape of the leather bowl, so that the design can be modernized and scientific.
5) the manufacturing method of the leather bowl mainly adopts the method of hydraulic forming and pressing and forming,
and gradually transfers to the pressing and molding. But for the cloth type cup remained flat type hot press molding method,
manual loading so that the rubber blank size shape, material weight and loading methods, on the quality of the leather bowl has important influence.
 Because the hardness of the bowl is very high, usually more than 8O degrees, so the preparation of rubber compound is also different.
 The formula of rubber content is relatively low, generally no more than 30% to 40%, and as far as possible without or with small amount of operating oil softener,
 in order to prevent work for hydraulic oil is extracted and the cup weight volume changes, affect the seal performance and effect.
 However, this kind of hard glue material is difficult to practice in manufacture, and it is difficult to mix evenly.
 It is usually necessary to adopt a multi stage temperature refining method to ensure the uniform quality of the adhesive.
6) in addition, as the hardness of the rubber is very high, therefore, the shape of the blank and the accuracy of the weight must be strictly controlled when the glue is filled.
 At the same time, in order to obtain the precise shape and size of the lip and mouth of the life bowl, it is necessary to try to maintain the stability of the pressure in the mold cavity,
 which does not cause excessive flow of rubber throughout the vulcanization process. This, for the precision leather bowl, is whether it can guarantee the performance of the extremely important conditions.