In the extrusion process, the plastic deformation of the blank is relative to the metal mold directional flow, the friction generated at the interface in the mold. It not only increases the deformation force, causing uneven deformation; while also pressing tool and mold caused by wear, significantly reduce the service life. Steel characterized in extrusion pressure, temperature, speed. Steel used in this extrusion lubricant must have the following characteristics: a suitable temperature in the extrusion of viscous, enough to ensure the lubricant itself is generated in the extrusion pressure without crowding; hot metal and cooling to ensure good insulation between the tools; on the contact surface with a low coefficient of friction.
Glass is a fluid, it has no significant change in temperature of liquid at room temperature, the viscosity of infinity, so similar to a solid, hard and brittle nature, and the thermal conductivity. After heating the glass temperature, the viscosity gradually decreased, when the glass softening prone to deformation without damage to the temperature is called the softening point. When the temperature exceeds the softening point of the glass, with the temperature gradually become adherent, the increased mobility of lower viscosity. In addition to the glass viscosity changes with temperature, but also its chemical composition, the chemical composition of the glass to glass softening point and viscosity of the lubricant has a great influence. Ugine made into various shapes at room temperature, such as glass, glass, glass cloth, glass, and glass frit, the glass frit inexpensive, and can be pressed into various shapes, the glass powder is mainly used. To improve the lubricating effect, should use the occasion to choose different size glass frit. Removing the glass film surface of the pipe extrusion used as a glass lubricant remaining on the extruded pipe external surface layer of a glass film, the nature of the hard and brittle, detrimental for subsequent processing and use, must be removed. Removal methods include mechanical and chemical methods. Mechanical method has peening, straightening and stretching methods such as water. Journal of Applied Chemistry clear glass film method, since the glass tube lubricant remaining on the surface with high chemical stability, clear it requires the use of an alkali solution or acid solution. Inadequacies of pickling that the erosion of various steel materials is great, the surface of the steel pipe may be too acid, in particular a greater erosion of carbon steel, so the application is subject to restrictions. PH joint clearance method currently used.
