Extrusion blow molding technology development, this technique is called 3D blow molding or 3D blow molding (also some countries call multidimensional extrusion blow molding MES).Due to the use of 3D blow molding is far less than that at the edge of the machining process of waste, not even waste removal, so also called waste or less waste and blow molding.
Three-dimensional (3D) crowded blowing hollow plastic is a forming method, which are frequently used plastic parison after being squeezed out, blown up and stick close by in advance in the side of the mold wall and the extrusion head or mold molding of the program for a second shaft or third axis rotation, when im similar shape parison with membrane cavity, on the other side of the mold closing and hold the parison, with subsequent parison separation, this is the whole parison be blown up and with membrane wall molding cavity.Production in this mode is similar to that of the air duct or pipeline on the car, not only flash less, and have no clamping line and to order products extrusion, make a lot of complex shape parts easily with a 3 d blow molding in processing forming.
The second forming methods mainly adopted can order operating mode, negative pressure molding process.It is the mold made can separate the upper and lower end of the process of sliding blocks, production mold clamping, first type tubular billet are drawn in the mold inside the negative pressure air move along the curve of the inner cavity, parison in place after the mold up and down slider closure and blow molding;This kind of forming method is more suitable for pipe products molding shape more rules.
The third molding method is to use a robot or manipulator clamping plastic parison and attached to the mold, blow molding, also can realize 3 d blow molding.
With conventional blow molding production process of the production of pipe bending, because of the parison flat folding width is much larger than products projection width, so will produce large amounts of waste edge (some height more than 50%), and a longer clip sew billet, not only affect the appearance, but also affect the strength of the products.
As the special 3 d blow molding technology, compared with the conventional waste edge blowing process, it has the following advantages.
Choose by clamping force formula, mold clamping forcePdie assembly=1.2P，P=qs, Can know 3 d blow molding projection area is much smaller than conventional blowing flat folding width, which is suitable for mold force, P q as the blowing pressure, s for clamping plane projection area, so the clamping force is far less than conventional clamping force needed for the blow molding process.
Resection margin greatly reduces the workload.
Don’t have to rebuild the diameter of molding items.
Molding goods quality has improved, because the wall thickness distribution design, not less intensity of mould.
Due to the shrinking of leftover material, less time, reduce the degradation of heat sensitive material probability.
Due to a large reduction in the waste side, the production of smaller extruder can be adopted.
Due to the three-dimensional blow molding has the above characteristics, making this kind of method become the manufacture of automobile bending pipe and pipe of the ideal technology. The parts which can be made by the three-dimensional blow molding are included; the air guide pipe of the turbocharged diesel engine, the special cooling medium conduit and the fuel supplementary pipe. In some developed countries, three-dimensional blow molding technology has in certain areas of application, instead of the other technology made the oil filling pipe, seamless door handles and other parts. In addition three-dimensional blow molding technology in the field of off-road vehicle parts, furniture (chair backrest and the chair legs), large pipe device also has potential application value; three-dimensional blow molding technology has a very attractive prospects for development.
Three dimensional blow molding technology is suitable for the manufacture of complex plastic pipe parts, the parts will not be easy to cause damage of the parting line, and no fly edge, but also can improve the wall thickness uniformity of hollow blow parts. D blow molding technology can promote the integration of parts, no assembly parts, so as to reduce the cost of. At present, the technology is making the product quality, production cost and production efficiency along with the production of the sequence structure and sandwich structure, which will be used in our country.