Layout principle of die ejector pin
(1) The ejector pin shall be arranged so that the jacking force is balanced as much as possible. The demoulding force required for the parts with complex structure is large, and the number of ejector pins shall be increased accordingly.
(2) The thimble shall be set at effective parts, such as bone position, column position, step, metal insert, local thick glue and other parts with complex structures. The thimbles on both sides of the bone and column positions shall be arranged symmetrically as far as possible, and the edge spacing between the thimble and the bone and column positions is generally d=1.5mm. In addition, try to ensure that the center line of the ejector pins on both sides of the column passes through the center of the column.
(3) Avoid setting the thimble across steps or on the inclined plane. The top surface of the thimble should be as flat as possible. The thimble should be placed at the structural part with good stress on the rubber part.
(4) Flat thimble shall be used when it is difficult to arrange dome needle in the deep bone position of the rubber part (depth ≥ 20mm). When using flat thimble, the flat thimble shall adopt the form of insert as far as possible to facilitate processing.
(5) Avoid sharp steel and thin steel, especially the top surface of the ejector pin can not touch the front formwork surface.
(6) The side distance between the ejector pin and the water channel shall be considered in the layout of the ejector pin to avoid affecting the processing and water leakage of the water channel.
(7) Considering the exhaust function of the ejector pin, in order to exhaust during ejection, the ejector pin shall be arranged at the position where vacuum pumping is easy to occur.
(8) For rubber parts with appearance requirements, the thimble shall not be arranged on the appearance surface, and other ejection methods shall be adopted.
(9) For transparent rubber parts, the thimble shall not be arranged at the position requiring light transmission.
Selection principle of die thimble
(1) Select the thimble with larger diameter. That is, when there is enough ejection position, the ejector pin with larger diameter and preferred size shall be selected.
(2) The specification of thimble shall be as few as possible. When selecting the thimble, the size of the thimble shall be adjusted to minimize the size specification, and the preferred size series shall be selected as far as possible.
(3) The selected ejector pin shall meet the ejection strength requirements. During ejection, the thimble shall bear a large pressure. In order to avoid bending and deformation of the small thimble, when the diameter of the thimble is less than 2.5mm, the supporting thimble shall be selected.