Molding apparatus and method for producing articles molded through sequential injection

Patent metadata

Field	Value
Publication number	US-9919462-B2
Application number	US-201514961173-A
Country	US
Kind code	B2
Filing date	Dec 7, 2015
Priority date	Dec 10, 2014
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

A molding apparatus for the production of articles molded through sequential injection includes a mold having a cavity, a plurality of electrically actuated injectors arranged at central, intermediate and end positions, respectively, with respect to the mold cavity, and an electronic system for controlling the injectors for the actuation thereof according to a sequential cycle which provides for opening the central injector first, followed by the intermediate injectors and then the end injectors. The electronic control system is configured so that the opening sequential cycle occurs in such a way to obtain more linear and homogeneous pressure in the mold filling step, and lower packing pressure.

First claim

The invention claimed is:

1. A molding apparatus for the production of articles molded by sequential injection, comprising a mold having a cavity, a plurality of electrically actuated injectors including a central injector, intermediate injectors and end injectors arranged at central, intermediate and end positions, respectively, with respect to the mold cavity, and an electronic control system controlling the injectors for actuation thereof according to a sequential cycle which provides for opening the central injector first, followed by the intermediate injectors and then the end injectors, wherein said electronic control system is configured in such a way that:
the central injector is opened in a relatively rapid fashion up to a maximum opening value, then held at said maximum opening value, then partially closed to a minimum opening value and held at such minimum opening value, and
the intermediate injectors and the end injectors are opened in succession in a less rapid fashion up to respective maximum opening values lower than said maximum opening value of the central injector and higher than said minimum opening value of the central injector, subsequently held at said respective maximum opening values until partially closed down to respective minimum opening values higher than said minimum opening value of the central injector and held at such minimum opening values until closing of the central, intermediate and end injectors.

2. The apparatus according to claim 1 , wherein the maximum opening value of the central injector is lower than a complete opening of the central injector.

3. The apparatus according to claim 1 , wherein the intermediate injectors and the end injectors are opened in succession respectively during and after partial closing of the central injector to said minimum opening value.

4. The apparatus according to claim 1 , wherein partial closing of the central injector from the maximum opening value to the minimum opening value is carried out less rapidly than opening thereof to said maximum value.

5. The apparatus according to claim 1 , wherein opening of the intermediate and end injectors up to the respective maximum opening values is carried out in a progressively more rapid fashion from the intermediate injectors to the end injectors.

6. The apparatus according to claim 1 , wherein the maximum opening values of the intermediate and end injectors are progressively increasing from the intermediate injectors to the end injectors.

7. The apparatus according to claim 1 , wherein the minimum opening values of the intermediate and end injectors are progressively increasing from the intermediate injectors to the end injectors.

8. The apparatus according to claim 1 , wherein said minimum opening values of the injectors correspond to a packing step of the plastic material in the mold cavity, and wherein in said packing step, the pressure in the mold cavity at the central injector is low and only slightly higher than the pressure at said intermediate injectors and end injectors.

9. The apparatus according to claim 1 , wherein complete closing of the injectors occurs simultaneously.

10. The apparatus according to claim 1 , wherein the central injector is opened and partially closed during a filling step of the plastic material into the mold cavity and held at such partially closed position through a portion of the filling step and through a packing step of the plastic material in the mold cavity until closed; wherein the intermediate and end injectors are opened and held at their respective maximum opening values until an end of the filling step; and wherein after a transition from the filling step to the packing step, the intermediate and end injectors are partially closed down to and held at their respective minimum opening values until the central, intermediate and end injectors are simultaneously closed.

11. A molding method for the production of articles molded by sequential injection in a mold cavity by using a plurality of electrically actuated injectors including a central injector, intermediate injectors and end injectors arranged at central, intermediate and end positions, respectively, with respect to the mold cavity, wherein the injectors are actuated according to a sequential cycle providing for opening the central injector first, followed by the intermediate injectors and then the end injectors, wherein the method includes the following steps:
the central injector is opened in a relatively rapid fashion up to a maximum opening value, then held at said maximum opening value, then partially closed down to a minimum opening value and held at such minimum opening value, and
the intermediate injectors and the end injectors are opened in succession in a less rapid fashion up to respective maximum opening values lower than said maximum opening value of the central injector and higher than said minimum opening value of the central injector, subsequently held at said respective maximum opening values until partially closed to respective minimum opening values higher than said minimum opening value of the central injector and held at such minimum opening values until closing of the central, intermediate and end injectors.

12. The method according to claim 11 , wherein the maximum opening value of the central injector is lower than a complete opening of the central injector.

13. The method according to claim 11 , wherein the intermediate injectors and the end injectors are opened in succession respectively during and after partial closing of the central injector down to said minimum opening value.

14. The method according to claim 11 , wherein partial closing of the central injector from the maximum opening value to the minimum opening value is carried out less rapidly than opening thereof to said maximum value.

15. The method according to claim 11 , wherein opening of the intermediate and end injectors up to the respective maximum opening values is carried out in a progressively more rapid fashion from the intermediate injectors to the end injectors.

16. The method according to claim 11 , wherein the maximum opening values of the intermediate and end injectors are progressively increasing from the intermediate injectors to the end injectors.

17. The method according to claim 11 , wherein the minimum opening values of the intermediate and end injectors are progressively increasing from the intermediate injectors to the end injectors.

18. The method according to claim 11 , wherein said minimum opening values of the injectors correspond to a packing step of the plastic material in the mold cavity, and wherein in said packing step, the pressure in the mold cavity at the central injector is low and only slightly higher than the pressure at said intermediate injectors and end injectors.

19. The method according to claim 11 , wherein complete closing of the injectors occurs simultaneously.

Assignees

• Inglass Spa

Inventors

• Bazzo Maurizio

Classifications

• B29C2945/76862

  Holding, dwelling · CPC title

• B29C2945/76859

  Injection · CPC title

• B29C45/0046

  Details relating to the filling pattern or flow paths or flow characteristics of moulding material in the mould cavity · CPC title

• B29C45/0025 Primary

  Preventing defects on the moulded article, e.g. weld lines, shrinkage marks (preventing defects on the preformed parts or layers B29C45/14836) · CPC title

• B29C45/281

  Drive means therefor · CPC title