潜伏式和牛角式浇口（英文资料）
Because they extend under the mold parting surfaces, tunnel gates can reach surfaces or features that are not located on the parting line. The gates typically feed surfaces oriented perpendicular to the mold face. Depending upon their design, they degate during ejection or mold opening (see figures 7-33 and 7-34). Tunnel gates that degate during mold opening often require a sucker pin or a feature similar to a sprue puller to hold the runner on the ejector half of the mold. The runner must flex for the gate to clear the undercut in the mold steel.
The gate may break or lock in the mold if the runner is too stiff or if the ejector pin is too close to the gate. Normally,the ejector pin should be at least two runner diameters away from the base of the gate.
The orifice edge closest to the parting line must remain sharp to shear the gate cleanly. When molding abrasive materials such as those filled with glass or mineral,make the gate of hardened or specially treated mold steel to reduce wear. Also,consider fabricating the gate on an insert for easy replacement. The drop angle and conical angle must be large enough to facilitate easy ejection (see figure 7-35). Stiff materials, glass-filled grades for example, generally require drop angles and conical angles at the high side of the range shown in the figure. The modified-tunnel gate design (see figure 7-36) maintains a large flow diameter up to the gate shearoff point to reduce pressure loss and excessive shear heating.
[ 本帖最后由 szlxm123 于 2007-6-26 06:16 编辑 ] |
发表于 2007-6-26 01:50:12
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