At present, the domestic silicon rubber skirt sheath and mandril molding process mainly includes three molding processes: integral injection, integral mold pressing and extrusion of single skirt sheath.
1. Molding process of umbrella skirt suit
Early composite insulators umbrella skirt, sheath and core rod sheathed inside diameter of molding process is to use the umbrella skirt with mandrel diameter minus tolerance, sheathed inside diameter of expansion umbrella skirt, a single umbrella skirt individually packed set on the mandrel, mandrel and umbrella cover with dielectric type of adhesive bonding interface, the resulting early composite insulators umbrella adhesive glue vacuum technology.The process is not complex, but the process requirements are high, many processes, low work efficiency, easy to cause internal insulation breakdown accident due to poor bonding.
The process has now been phased out.
2. Extrusion molding process of single umbrella skirt suit after sheath To solve the defects of skirt suit molding process, the integral extrusion molding process of skirt suit jacket, which is extruded by extrusion press and directly coated on mandrel, has been widely used.In this process, sheath and mandrel are integrated, and the strength of interface coupling is much higher than that of silicone rubber.Can ensure the internal insulation of the product, and can adjust the product structure height, creepage distance and umbrella structure according to the user's request, convenient and flexible.
3. Integral forming Process The process features the skirt jacket forming and the mandrel bonding in the mold at one time.Early divided into integral molding and integral injection molding two processes.Strictly speaking, monolithic injection and monolithic molding are the same molding process.The integral molding process is semi-automatic or automatic when semi-finished products are made. No interface between each part of umbrella cover, skirt, umbrella cover and umbrella cover is caused by two molding.It not only reduces the type and quantity of interface and adhesives, but also can produce products of any length, with high degree of automation, consistency and stability of quality, high efficiency, excellent electrical performance, economical and applicable advantages.Now, another widely used molding process is the high temperature, high pressure integral injection molding process.It has the same advantages as the integral molding process, but in the early integral injection molding process, the impact of high temperature and high pressure silicone rubber on the mandrel will cause certain damage to the mandrel, which is easy to cause the sheath eccentricity.After the mandrel positioning device is adopted at present, the eccentricity of the jacket is reduced from the early 3 ~ 4mm to less than 0.5mm.