Demoulding mechanism of the launch
thrust point should function in rigid plastic good place, such as ribs, flange, the shape pieces of shell wall edge, try to avoid thrust point effect on parts of thin plane, prevent rupture and perforation, such as shell shape and cylindrical plastic parts use the push rod. So that the uniform stress, deformation and not too bad. With push rod was introduced, the push rod role in plastic parts surface area is calculated, in case the white plastic launch force is too large or deformation of plastic scrap.
in the design of the mold, should as far as possible the selection of standard mould base and standard parts, so a large part of standard parts are readily available in the market to buy, this is to shorten the manufacturing cycle, reduce the manufacturing cost is extremely advantageous. Die set sizes determined, the mold related parts to make the necessary strength or stiffness calculation, to check whether the selected die set appropriate, especially for large mold, it is very important.
launch institution shall make out the reliable, flexible and convenient manufacturing, institutions themselves should have enough strength, stiffness and hardness, to withstand the forces in the process of launch, ensure smooth demoulding of plastic parts. Introduced the position of the plastic parts should be in as far as possible plastic parts or hidden surface and the internal decoration, for transparent plastic parts especially must pay attention to the choice of the form of ejector location and ejector, lest the launch marks affect the appearance of the plastic parts quality. Design agency, also the correct reset when clamping mechanism, and to ensure that does not interfere with other mould parts. Launch institutions according to the kinds of power source can be divided into manual, motor launch and hydraulic pneumatic launch.
ejection force refers to the plastic parts out from the core needed to overcome resistance. He is one of the important basis of demoulding mechanism design. But the ejection force calculation and measurement is very complex. For engineering practice shells of any shape plastic ejection force, it can only be reduced for the circular or rectangular approximate calculation. Ejection force of accurate calculation is difficult, it with plastic tensile elastic modulus, thermal expansion coefficient, mold temperature, pressure, cooling time, when the mould cavity pressure and process conditions, such as push rod speed and surface roughness and polishing mold core is along the parting direction.
launch institutions should be set at the side of the dynamic model. Due to the launch of movement through the loading on the injection molding machine clamping mechanism of plunger to drive, so usually, launch institutions at the side of the dynamic model. Therefore, in the parting surface design should pay attention to as far as possible, after open mold injection molding processing parts can stay in dynamic model on one side. In order to ensure that plastic deformation and damage in the process of launching, parts for mould design should be analyzed carefully in bag tight force and adhesive force of size, the choice of reasonable way and launch position.
to reliable, should increase the launching device in the area of the plastic pieces of the role. In the case of the mould structure design allows for simple parts should be as much as possible to decorate some push rod, for complex parts should adopt some comprehensive multiple agencies. Standard parts including general standard and special standard mold two kinds big. General standard parts such as fasteners, etc. Die standard parts such as the location ring, gate set, push rod,, guide pin, guide sleeve, ejector pin mold special spring, cooling and heating elements, order parting mechanism and precision positioning using standard components, etc.
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