JP2019188790A - Drooling and spew prevention method of injection molding - Google Patents

Abstract

To provide an injection molding method and a sprue bushing (mold component); in the previous arts, there have been cases where a temperature is elevated as much as possible when desirable conditions in resin injection molding and in a resin melt temperature of molding condition for a product are searched for; there are cases where products have defects, even at a temperature lower than the critical temperature of the resin, due to drooling of a resin from a tip of a nozzle during wait periods or spew phenomenon where the product threads from the nozzle when taking the product out.SOLUTION: In the method, by using movements of opening/closing of a mold, and back-and-forth movements of a nozzle vertical to an opening of the mold, a component having a flow passage of a resin in a sprue bushing 3 is rotated. By this, a flow passage is mechanically shutoff around a mold inlet. This mold movement and use of the sprue break coincidence with the shutoff timing while injection is on hold.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to an injection mold that is designed to prevent cracks and damage during injection molding.

  The injection of the resin from the injection molding machine into the mold is performed with the nozzle tip of the injection molding machine contacting the sprue bush of the mold (nozzle touch). The resin of the molding material is melt-kneaded in the cylinder part of the molding machine and injected into the product shape part of the mold at a high pressure from an injection nozzle attached to the tip of the cylinder.

  The fluidity of the resin during injection molding is important for product quality, and the degree of fluidity and the relationship between temperature and fluidity are characterized by the resin. For this reason, some resins are injected into the mold in a state of high fluidity at high temperatures.

  If the flowability of the resin is increased at the location of the injection nozzle in order to reduce the injection resistance, so-called rustling or leakage of the sprue from the nozzle occurs when the resin leaks from the nozzle hole even when the product is taken out after the injection is stopped. If the leaked resin is not stored in the cold slug when the fluidity is lowered in the sprue hole, it will cause molding defects. In addition, since the amount of leakage is not constant, the amount of injected resin varies, and molding conditions are not determined, which also leads to molding defects. Itohiki may cause molding defects due to adhesion of the resin it to the product, and damage the mold when the resin it adheres to and sandwiches the mold. This may hinder unattended molding.

  When the molded product is taken out, the resin is melted and kneaded in preparation for the next injection operation on the cylinder side, and the resin pressure at the injection nozzle portion is increased, so that the rape phenomenon may be promoted. In such a case, the shut-off nozzle is effective, but usable resin is limited and expensive.

Japanese Patent Laid-Open No. 06-068810

  It is an object of the present invention to provide a sprue bush (mold part) in which the so-called hanatare 28 and cypress 29 are prevented.

  2 (a, b) and 15 (a , B), the rotary shaft parts 1 (a, b) and 14 (a, b) having resin passages are rotated, thereby sealing the resin. In Itohiki, it is cut. The rotating shaft parts 1 and 14 can be rotated by using the motion of sliding parts 2 and 15 arranged perpendicular to the mold and by fixing the parts 2 and 15 and rotating the rotating shaft parts 1 and 14. It is performed by moving in the direction perpendicular to the mold while being hooked on 2 and 15.

  When the nozzle 24 touches the vicinity of the resin inlet of the sprue bushes 3 and 16 and when the cistern is cut, there is a slight amount of resin remaining on the resin path of the rotating shaft part, but it is a small amount that can be planned. Proper provision of the cold slugs 6 and 19 prevents the product and runner from being filled with Hanatare and Itohiki resin.

  FIG. 1 illustrates the structure of a three-plate mold. The fixed-side molds 7, 8, and 9 have nine fixed main molds moved in the direction of 10 and the stripper plate 8 moved in the direction of 11. FIG. At this time, the cylinder 4 moves together with 8 and is caught by the component 2 when the distance 13-a from the entrance of the sprue bush 3 to the resin passageway of the rotary shaft component 1 is exceeded, and the rotary shaft component 1 is rotated.

  FIG. 2 illustrates the structure of a two-plate mold. The movable main mold 21 moves in the direction 22 and the molded product 18 is pulled to the movable side. When the tip of the sprue exceeds the distance 23-a from the entrance of the sprue bushing 16 to the resin passageway of the rotating shaft part 14, a spring 25 that performs a sprue break (lowering the nozzle) acts on the nozzle 24 in the opposite direction of the bushing 22. The rotary shaft component 14 rotates in conjunction with this movement of the movement of 16.

  FIG. 3 illustrates the images of the rotating shaft parts 1 and 14 and the parts 2 and 15.

The invention's effect

  It is possible to mechanically prevent the so-called Hanatare Itohiki, which is a problem during resin molding. Conventionally, the melting temperature of the resin required as molding conditions could not be carried out due to Hanatare and Itohiki. However, it is possible to raise the melting temperature by mechanically preventing it.

  In the case of resin molding, there is a case in which Hanatare Itohiki occurs even if the melting temperature is not raised so much, in which case there is a case where manned molding is performed instead of automatic molding. You are free from such inefficient work.

  Example when carrying out the present invention with a three-plate mold (a part of hatching is omitted)   Example of carrying out the present invention with a two-plate mold (a part of hatching is omitted)   Enlarged images of 1 and 2 in FIG. 1 and 14 and 15 in FIG.   Hanatare image (some hatchings omitted)   Itohiki image (some hatchings omitted)

1-a Rotating shaft part when mold is closed 1-b Rotating shaft part when mold is opened 2-a When the mold is closed, a force perpendicular to the mold is applied to the rotating shaft part Part 2-b Part 3 which gives the rotating shaft part a force perpendicular to the mold when the mold is opened 3 Sprue bush 4 Cylinder 5 Molded product 6 Cold slug 7 Fixed mounting plate 8 Stripper plate 9 Fixed main mold 10 Fixed main Mold opening direction 11 Stripper plate opening direction 12 Distance required to rotate the rotating shaft part 13 Distance until the product sprue exceeds the end of the rotating shaft part 14-a Rotation when the mold is closed Shaft component 14-b Rotating shaft component 15-a when the mold is opened 15-b Component 15-b which applies a force perpendicular to the mold to the rotating shaft component when the mold is closed Mold when the mold is opened Rotating axis with mold and vertical force Parts to be given to parts 16 Sprue bushing 17 Cylinder 18 Molded product 19 Cold slug 20 Fixed main mold 21 Movable main mold 22 Fixed main mold opening direction 23-a Distance from sprue bushing inlet to rotating shaft part end 23-b Sprue bushing Distance from inlet to end of rotating shaft part 24 Molding nozzle 25 Enlarged image of springs 26-a 2 and 15 Enlarged image of 26-b 2 and 15 Enlarged image of 27-a 1 and 14 Enlarged image of 27-b 1 and 14 Image 28 Hanatare image 29 Itohiki image

Claims (2)

  In injection molding, cylinders, cones, polygonal cylinders, and polygonal pyramid parts (in the drawing, cylinders) that are perpendicular to the mold due to opening and closing of the mold and sprue break (advance and retreat of the nozzle) For example, 2-ab 15-ab (Fig. 3 26-ab) is used, and a rotary shaft component (in the drawing, 1-ab 14-ab 27-ab) provided with a flow path incorporated near the resin inlet of the sprue bushing. Rotating shaft parts are rotated by meshing with (example). As the rotating shaft component rotates, the flow path is blocked and mechanical damage is cut off. At the same time, if it occurs, the resin thread is cut.   The present invention is interlocked with a process that is always performed, that is, opening and closing a mold, and a frequently performed process, that is, sprue break. Is realized in the conventional process.

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