First, large size, large size O Ring Seals production process
1, the choice of large-size O Ring Seals to pay attention to the following technical details
(1) to calculate the pre-stretch (piston seal) or pre-compression rate (piston rod seal), section shrinkage;
(2) pay attention to the seal and sealed liquid compatibility, to take into account the swelling of the seal;
(3) also consider the thermal expansion of the seal.
For example, the piston seal: seal groove diameter is 780, then you ordered the seal diameter (including tolerance) at least less than or equal to 780; if the piston rod seal: If the groove diameter is 780, then you order The outer diameter of the seal (including tolerances) is at least equal to or greater than 780.
2, large-size O Ring Seals processing methods
Large-scale non-standard O Ring Seals processing methods, mold design, the use of upper and lower mold design long strip multi-cavity mold, mold ends closed and removable to ensure high pressure vulcanization, the upper and lower molds were installed at temperatures of 30 to 250 ℃ The upper and lower molds are installed at both ends of the upper and lower molds at an adjustable temperature of 30 to 250 ° C. Assuming that the upper and lower mold temperatures are between 150 and 220 ° C, the upper and lower molds are tested for dust removal and controlled to heat up. Non-standard O Ring Seals diameter required to prepare the width and height of the determination of the strip, the strip into the mold cavity of the upper and lower mold after the mold, the upper and lower mold closed pressure vulcanization; After removing the upper and lower molds, the vulcanization is carried out until the length of the strip reaches the total length and then the docking is completed until the whole O Ring Seals is connected to the post-trimming test to realize the preparation of the large-scale non-standard O Ring Seals.
Second, Dingqing rubber O Ring Seals oil resistance
Dingqing rubber O Ring Seals can withstand most of the oil, especially resistant to paraffin oil, oil is divided into two kinds of alkane oil and aromatic oil, alkane oil refers to the molecular structure of the chain, aromatic hydrocarbon chain refers to the chain containing benzene ring Such as common gasoline, oil, diesel, peanut oil, soybean oil and so on are paraffinic oils; and pine tar and coal tar are aromatic oil. Which is still relatively easy to understand, Dingqing rubber molecular chain contains -CN (cyano) groups, is a polar rubber, and alkane oil molecular chain is straight, without the former polar groups, non-polar structure, Aromatic oil containing benzene ring and other ring structure, but also showing a strong polarity, that is, the so-called "similar compatibility" principle.
Dingqing rubber O Ring Seals referred to as NBR. A synthetic rubber obtained by copolymerizing butadiene and acrylonitrile. Dingqing rubber O Ring Seals with its excellent oil resistance and the achilles said its oil resistance after the polysulfide rubber, acrylic rubber and fluorine rubber, in addition to Dingqing rubber O Ring Seals also has a good wear resistance, anti-aging Sexual and air tightness, but the resistance to ozone, electrical insulation and cold resistance are relatively poor, and better conductivity.