1. The principle of thimble layout (1) The ejector pin […]
1. The principle of thimble layout
(1) The ejector pin arrangement should make the ejection force as balanced as possible. The demoulding force required for the complex structure is large, and the number of thimbles should be increased accordingly.
(2) The thimble should be set in effective parts, such as bone position, column position, steps, metal inserts, local thick glue and other structurally complex parts. The thimbles on both sides of the bone position and the column position should be arranged symmetrically as much as possible. The distance between the thimble and the bone position and the column position is generally D=1.5mm. In addition, the imported plastic agency should try to ensure that the center connection line of the thimble on both sides of the column position passes through. Column center.
(3) Avoid setting thimbles across steps or on inclined surfaces. The top surface of the thimbles should be as smooth as possible, and the thimbles should be arranged in the structural parts where the plastic parts are well stressed.
(4) Fengsu Technology should use a flat thimble when the plastic part is deep in the bone (depth ≥ 20mm) or when it is difficult to arrange a round thimble. When a flat thimble needs to be used, the flat thimble should be in the form of an insert to facilitate processing.
(5) Avoid sharp steel and thin steel, especially the top surface of the thimble should not touch the front die surface.
(6) The distance between the thimble and the waterway should be considered in the arrangement of the thimble to avoid affecting the processing and leakage of the waterway.
(7) Considering the exhaust function of the thimble, in order to exhaust the ejection, the thimble should be arranged in the part where it is easy to form a vacuum. For example, at the larger plane of the cavity, although the packing force of the plastic part is small, it is easy to form a vacuum, which leads to an increase in the demoulding force.
(8) For plastic parts with appearance requirements, the ejector pins cannot be arranged on the appearance surface, and other ejection methods should be used.
For transparent plastic parts, the thimble cannot be arranged in the part that needs to transmit light.