Injection device of light metal injection molding machine and injection control method thereof

Patent metadata

Field	Value
Publication number	US-10967426-B2
Application number	US-201916591639-A
Country	US
Kind code	B2
Filing date	Oct 3, 2019
Priority date	Oct 5, 2018
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

An injection device of light metal injection molding machine and an injection control method thereof are provided, in which a melt in a supply unit is supplied into an injection unit through a communication passage, a plunger of the injection unit is retracted to measure the melt, the communication passage is closed, and the plunger is advanced to inject the melt into a mold device through an injection nozzle of the injection unit. After the injection and before the measurement, the plunger is advanced under a pressure at which the melt does not come out from the injection nozzle to make the melt in the injection unit flow back into the supply unit through the opened communication passage.

First claim

What is claimed is:

1. An injection control method of an injection device of light metal injection molding machine, a molding cycle is carried out repeatedly such that a molded article is obtained, in the molding cycle, a melt of a light metal material in a supply unit is supplied into an injection unit through a communication passage, a plunger included in the injection unit is retracted and the melt of a predetermined volume in the injection unit is measured, the communication passage is closed, and the plunger is advanced to inject the melt in the injection unit into a mold device through an injection nozzle included in the injection unit, wherein
at a frequency of once for every cycle or every plural cycles in the repeated molding cycles, in the duration after the melt is injected and before the melt is measured, the plunger is advanced under a pressure at which the melt in the injection unit does not come out from the injection nozzle and at least part of the melt in the injection unit is flowed back into the supply unit through the communication passage that is opened.

2. The injection control method of an injection device of light metal injection molding machine according to claim 1 , wherein before the melt is flowed back, the plunger is retracted, and the melt is replenished from the supply unit into the injection unit through the communication passage.

3. The injection control method of an injection device of light metal injection molding machine according to claim 2 , wherein the melt is replenished in the injection unit exceeding the predetermined volume of the melt during measurement, the melt of the predetermined volume remains in the injection unit, and the melt is flowed back to be measured.

4. The injection control method of an injection device of light metal injection molding machine according to claim 1 , wherein after the melt is flowed back, the plunger is retracted, the melt is replenished from the supply unit into the injection unit through the communication passage, and again the melt is flowed back; the above operation is carried out for at least once, and thereafter the melt is measured.

5. The injection control method of an injection device of light metal injection molding machine according to claim 4 , wherein the melt is replenished in the injection unit exceeding the predetermined volume of the melt during measurement, the melt of the predetermined volume remains in the injection unit, and the melt is flowed back to be measured.

6. The injection control method of an injection device of light metal injection molding machine according to claim 1 , wherein when the communication passage is closed, a valve rod is cooled by a cooling medium flowing inside the valve rod, a semisolid of the melt is generated around the valve rod, the valve rod is seated on a valve seat formed around a supply unit side opening of the communication passage to close the communication passage, and a space between the valve seat and the valve rod seated on the valve seat is sealed by the semisolid; and when the communication passage is opened, the space between the valve seat and the valve rod is opened by being separated at a distance of equal to or less than 20% of an inner diameter of the communication passage, and the semisolid between the valve seat and the valve rod is removed by the melt that is flowed back.

7. The injection control method of an injection device of light metal injection molding machine according to claim 1 , wherein a measurement position of the plunger when the predetermined volume is measured is detected, and an advance position of the plunger when the plunger advances from the measurement position under a predetermined pressure is detected.

8. An injection device of light metal injection molding machine, comprising:
a supply unit which supplies a melt of a light metal material;
an injection unit in which a plunger advancing and retracting is disposed and to which an injection nozzle is connected;
a coupling member which couples the supply unit and the injection unit, and in which a communication passage communicating an interior of the supply unit and an interior of the injection unit is formed;
a backflow prevention device which opens and closes the communication passage; and
an injection control unit configured to control the supply unit, the injection unit, and the backflow prevention device, and carry out a series of control that: a molding cycle is carried out repeatedly such that a molded article is obtained, in the molding cycle, the melt in the supply unit is supplied into the injection unit through the communication passage, the plunger is retracted to measure the melt of a predetermined volume in the injection unit, the communication passage is closed, and the plunger is advanced to inject the melt in the injection unit into a mold device through the injection nozzle, and carries out a series of control that: at a frequency of once for every cycle or every plural cycles in the repeated molding cycles, in the duration after the melt is injected and before the melt is measured, the plunger is advanced under a pressure at which the melt in the injection unit does not come out from the injection nozzle, and at least part of the melt in the injection unit is flowed back into the supply unit through the communication passage that is opened.

9. The injection device of light metal injection molding machine according to claim 8 , wherein the injection control unit carries out a series of control that: before the melt is flowed back, the plunger is retracted, and the melt is replenished from the supply unit into the injection unit through the communication passage.

10. The injection device of light metal injection molding machine according to claim 9 , wherein the injection control unit carries out a series of control that: the melt is replenished in the injection unit exceeding the predetermined volume of the melt during measurement, the melt of the predetermined volume remains in the injection unit, and the melt is flowed back to be measured.

11. The injection device of light metal injection molding machine according to claim 8 , wherein the injection control unit carries out a series of control that: after the melt flows back, the plunger is retracted, the melt is replenished from the supply unit into the injection unit through the communication passage, and again the melt is flowed back, which is carried out for at least once, and thereafter the melt is measured.

12. The injection device of light metal injection molding machine according to claim 11 , wherein the injection control unit carries out a series of control that: the melt is replenished in the injection unit exceeding the predetermined volume of the melt during measurement, the melt of the predetermined volume remains in the injection unit, and the melt is flowed back to be measured.

13. The injection device of light metal injection molding machine according to claim 8 , wherein the backflow prevention device comprises a valve seat formed around on a supply unit side opening of the communication passage, a valve rod which is seated on the valve seat to close the communication passage and opens the communication passage by being separated from the valve seat, a valve rod driving device which drives the valve rod, and a cooling piping which is arranged inside the valve rod and through which a cooling medium flows;
the injection control unit carries out a series of control that: when the communication passage is closed, the valve rod is cooled by the cooling medium flowing through the cooling piping, a semisolid of the melt is generated around the valve rod, the valve rod is seated on

Assignees

• Sodick Co Ltd

Inventors

• Fujikawa Misao

Classifications

• B22D17/32 Primary

  Controlling equipment · CPC title

• B22D17/30

  Accessories for supplying molten metal, e.g. in rations (supplying molten metal in ration in general B22D39/00) · CPC title

• B22D17/2092

  Safety devices (for plastics B29C45/84) · CPC title

• B22D17/2015

  Means for forcing the molten metal into the die (for plastics B29C45/46) · CPC title

• B22D17/10 Primary

  with horizontal press motion · CPC title