In the design of indirect squeeze casting molds, due to the particularity of the structure of some parts, the central runner is required to feed the material. The purpose of the double parting surface is to take out the casting system between the intermediate plate and the fixed mold base plate. Compared with the single parting surface mold, the double parting surface squeeze casting mold adds a middle plate (floating plate) that can be moved locally in the fixed mold part, also called a three-plate mold.
1 Working principle of double parting surface squeeze casting mold Taking the fixed distance double parting surface mold of swing hook parting screw as an example, the working principle of double parting surface squeeze casting mold is introduced.
Pour the smelted aluminum alloy into the pressure chamber composed of the pressure sleeve 14 and the pressure head 13. The movable beam of the press drives the cushion block 2 connected with the movable mold seat plate 1, the movable mold plate 3, the movable mold sleeve plate 21, The middle plate 9 (fixed template) and other parts realize mold clamping; when the movable mold cover 21 and the middle plate 9 are closed, the swing hook 5 just hooks the stop 4; the ejector piston of the lower cylinder drives the ejector rod 12 and The pressure head 13 is pushed out to apply high pressure to the liquid (semi-solid) metal in the pressure chamber. Under the pressure, the liquid metal fills the cavity through the central runner and fully maintains the pressure.
When the mold is opened, because the swing hook fixed on the intermediate plate 9 pulls the stopper on the movable template 3 and the Z-shaped indenter, the mold is parted from the parting surface A, and the runner (including excess material) is broken . After parting to a certain distance, the swing hook swings and disengages under the action of the pressure block, and the intermediate plate 9 (fixed template) stops moving under the restriction of the limit screw 10, and the movable pressure plate drives the movable template 3 and the core 22 to continue. Move upward to achieve the second parting (B parting surface). When the push plate 25 contacts the ejector rod of the press, the ejection mechanism starts to work, and the push rod 27 pushes the part out of the mold. After taking out the parts and spraying the paint, the next working cycle can be carried out.
2 Problems that should be considered when designing double parting surface squeeze casting molds
(1) The parting distance of parting surface A is not only required to ensure the smooth removal of the pouring system (sprue), but also to facilitate the pouring of molten metal.
(2) Since the runners used in the double parting surface squeeze casting molds are mostly central runners, the runner cross-sectional area is large, only when the packing force of the part is large or the combined pull plate (rod) is used, Realize the separation (pulling off) of the remaining material and the sprue.
(3) Due to the large cross-sectional area of the central sprue, the sprue should be broken when the remaining material of the sprue is not completely solidified to reduce the breaking force.
(4) In the double parting surface mold, pay attention to the setting of the guide post and the length of the guide post. For general squeeze casting molds, the guide post is usually set on the core protruding parting surface longest