Valve needle plastic-sealing assembly and hot runner system

Abstract

The invention relates to the technical field of hot runners, and discloses a valve needle plastic-sealing assembly and a hot runner system. The valve needle plastic-sealing assembly comprises a spruebush, a hot nozzle, a valve needle and a guiding block. A sprue is formed in the sprue bush; the hot nozzle is arranged on the sprue bush and communicates with the sprue; the valve needle penetrates into the hot nozzle in the mode of being capable of moving in the axis direction of the valve needle, a plastic-sealing head in an inserted circular-truncated-cone shape is arranged at the end, penetrating through the hot nozzle, of the valve needle, the included angle alpha between the generatrix of the plastic-sealing head and the axis of the plastic-sealing head is 1-6 degrees, and the side wallof the plastic-sealing head can be attached to the inner wall of the sprue for blocking the sprue; and the guiding block is arranged in the hot nozzle, the valve needle penetrates through the guidingblock, and the guiding block is used for limiting the valve needle to move in the axis direction of the valve needle. Compared with an existing straight body plastic-sealing and bevel plastic-sealingstructure, through the valve needle plastic-sealing assembly, the manufacturing difficulty is lowered, the service life is prolonged, and the problems of sprue flash and sprue bulging are solved.

Description

technical field [0001] The invention relates to the technical field of hot runners, in particular to a valve needle sealing assembly and a hot runner system. Background technique [0002] The existing valve pin type hot runner system mainly includes two types of sealing methods for sprue sleeves: straight sealing and inclined surface sealing. Wherein, the gap between the straight body sealant, that is, the cylindrical sealant head of the valve needle and the sealant hole of the sprue sleeve is small enough to allow the plastic to solidify at a certain temperature to seal the sealant. Inclined surface sealing means that the sealing head of the valve needle is an inverted circular table body, and the sealing hole of the sprue sleeve is a circular table hole. The sealing principle is that the side wall of the sealing head of the valve needle and the inner wall of the gate of the sprue sleeve interact Press to seal. [0003] However, there are different problems in the two sea...

AI Technical Summary

Problems solved by technology

The sealing head of the existing inclined valve needle 400 is in the shape of an inverted circular platform. The angle α between the busbar and the axis of the sealing head of the inclined valve needle 400 is relatively large, and the standard angle is 20 degrees. The large angle α is due to the If the angle α is too small, it will not be able to compensate for the yaw error of the inclined valve needle 400 when it is closed, which will cause the sealing head of the inclined valve needle 400 to touch the gate of the inclined gate sleeve 500 when closing the gate of the inclined gate sleeve 500. damage to the inner wall of the mouth

However, when the slope valve needle 400 closes the slope sprue sleeve 500, relying on the contact pressure S of the sealing head of the slope valve needle 400 to the inner wall of the gate of the slope sprue sleeve 500 to extrude plastic, if the contact pressure S is insufficient, the plastic cannot be processed. If it is completely extruded, there will be a problem of gate flash

However, the angle α between the busbar and the axis of the sealing head of the existing slope valve needle 400 is relatively large. In order to completely seal the gate of the slope sprue bushing 500, under the condition that the required contact pressure S is constant, The larger the included angle α, the greater the sealing force F required, which will cause the gate of the inclined sprue sleeve 500 to protrude due to the excessive sealing force F received (gate protruding That is, under the extrusion of the sealing force F along the axial direction, the gate of the inclined sprue bushing 500 protrudes along the axial direction)

Therefore, the existing bevel sealant has the problems of gate flash and gate protrusion

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