Blow moulding machine for the manufacture of hollow bodies in thermo-plastic material.
Blow moulding machine for the manufacture of hollow bodies in thermo-plastic material.
In one type of known blow moulding machine, an extruder and a mould are both in fixed positions. In one design, the mould is directly below the head of the extruder. This means that continuous extrusion of a tube is not possible, as extrusion can only take place when the mould is open. When the mould is closed, the extrusion process must be interrupted. In a further design, the mould is at some distance blow moulding machinery. This system does not allow continuous extrusion. A transfer mechanism must be provided to remove the end of the tube from the extruder head and lower it into the open mould. When the mould is closed, the transfer mechanism moves upwardly and takes from directly below the extruder head a fresh tube end and then lowers this into the mould. In this design the blowing must be carried out from underneath. In a further design, the mould is below and laterally displaced from the extruder. Here, too, a transfer blow mold machine is necessary, but in this case it must perform with vertical and horizontal movements to take a tube end from the extruder head and transport it to the mould. As a result of this horizontal and then vertical movement to bring the tube into the mould, the additional risk of the tube oscillating occurs. In this case, the blowing process can be carried out from above. Moreover, a mould can be fitted on each side of the extruder, making a much faster extrusion process. In a further design, the extruder is in a fixed position and the mould is movable.
In a further design of blow moulding machines of this type, the extruder is movable and the mould is fixed. Here, the mould and the extruder lie on the same axis. The extruder must be movable vertically in an upward and downward direction. Blowing is only possible from underneath. Moreover, only one mould can be used.
In one type of known blow moulding machine, an extruder and a mould are both in fixed positions. In one design, the mould is directly below the head of the extruder. This means that continuous extrusion of a tube is not possible, as extrusion can only take place when the mould is open. When the mould is closed, the extrusion process must be interrupted. In a further design, the mould is at some distance blow moulding machinery. This system does not allow continuous extrusion. A transfer mechanism must be provided to remove the end of the tube from the extruder head and lower it into the open mould. When the mould is closed, the transfer mechanism moves upwardly and takes from directly below the extruder head a fresh tube end and then lowers this into the mould. In this design the blowing must be carried out from underneath. In a further design, the mould is below and laterally displaced from the extruder. Here, too, a transfer blow mold machine is necessary, but in this case it must perform with vertical and horizontal movements to take a tube end from the extruder head and transport it to the mould. As a result of this horizontal and then vertical movement to bring the tube into the mould, the additional risk of the tube oscillating occurs. In this case, the blowing process can be carried out from above. Moreover, a mould can be fitted on each side of the extruder, making a much faster extrusion process. In a further design, the extruder is in a fixed position and the mould is movable.
In a further design of blow moulding machines of this type, the extruder is movable and the mould is fixed. Here, the mould and the extruder lie on the same axis. The extruder must be movable vertically in an upward and downward direction. Blowing is only possible from underneath. Moreover, only one mould can be used.
In yet a further design, both the extruder and the mould are movable. Here, the mould travels in a circuit around a vertical or horizontal axis and the extruder is movable in an upward and downward direction. A transfer mechanism is not necessary, continuous extrusion is possible and a number of moulds can be used by being placed on a table, which is rotatable through a vertical or a horizontal axis.