What is hot melt adhesive?
Main function of hot melt adhesive machine is to fuse solid polymer, and then export in uniform homogeneity, constant temperature and stable pressure.It has two types: horizontal and vertical. The type with threaded rod installed horizontally is horizontal type; while that installed vertically is vertical type.Dismantling and maintenance for horizontal hot melt adhesive machine is convenient; but the threaded rod is in form of overhanging beam, of which the metering section will easily be worn.Threaded rod of vertical hot melt adhesive machine will not easily bend, thus there will be less abrasion on head. But the height of plant shall be increased, thus will be more difficult for dismantling and maintenance.Currently, horizontal hot melt adhesive machine is adopted in majority.
Hot melt adhesive machine, according to number of threads and screws, can be divided into single thread, double-thread, single screw and double-screw extruderAccording to rotating speed of screw, it can be divided into general type (rotating speed less than 100r/min) and high speed extruder. In recent years, the development speed of hot melt adhesive machine is relatively quick with development direction being upsizing, large length/diameter ratio, high speed and development of new screws. This section focus on introduction of structural characteristics, technical performance and working principle of horizontal general hot melt adhesive machine.
Materials are fed into screw channel via charge hole. The hot melt adhesive machine is pushed forward by rotation of screw.Hot melt adhesive machine absorbs heat energy supplied by heating unit continuously; on the other side, due to the friction between hot melt adhesive machine and hot melt adhesive machine, hot melt adhesive machine and screw & sleeve, as well as shearing action between liquid layers, partial mechanical energy is converted into heat energy. Hot melt adhesive machine gradually fuse the glue into melt by the increasing temperature during the advancing progress.During the melting, polymers are changing on temperature, pressure, viscosity and form, converted from solid (glass type) into highly elastic. Along with the further increase of temperature, plastic flow occurs, converting into viscous fluid (viscous flow state).Polymer in viscous flow state, by pushing of screw and resistance on screw exit, is transmitted to melt pipes with certain pressure.
Polymer fusing device: mainly composed by screw and sleeve. Its function is to extrude solid materials, accompanied by external heating, to fuse them into uniform melt. Then, extrude it from the head of screw with certain temperature, pressure and discharge volume, sent to spinning device via melt pipes for spinning.
Heating and cooling system: mainly composed by aluminum sheath heater and water cooling jacket. Its function is to ensure extrusion of polymer within the temperature range required by the process by heating and cooling of sleeve.
Drive system: mainly composed by variable-speed motor and gearbox. Its function is to ensure screw operating stably and uniformly in required torque and speed.