Injection device and molding apparatus

Patent metadata

Field	Value
Publication number	US-9968998-B2
Application number	US-201615079558-A
Country	US
Kind code	B2
Filing date	Mar 24, 2016
Priority date	Mar 27, 2015
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

An injection device has an injection cylinder for driving a plunger, a gas pressure type accumulator which supplies hydraulic fluid to the injection cylinder, a hydraulic fluid supply device which supplies the hydraulic fluid to the accumulator, a pressure sensor for detecting the gas pressure of the accumulator, and a control device which controls the hydraulic fluid supply device so as to suspend the supply of the hydraulic fluid when detection value of the pressure sensor reaches a predetermined target gas pressure before injection in the state where the hydraulic fluid is supplied from the hydraulic fluid supply device to the accumulator in a molding cycle.

First claim

The invention claimed is:

1. An injection device comprising:
an injection cylinder for driving a plunger,
a gas pressure type accumulator which supplies a hydraulic fluid to the injection cylinder,
a hydraulic fluid supply device which supplies the hydraulic fluid to the accumulator,
a pressure sensor for detecting gas pressure of the accumulator,
an input device which accepts input of a target value of final pressure of a molding material; and
a control device which controls the hydraulic fluid supply device so as to suspend the supply of the hydraulic fluid when a detection value of the pressure sensor reaches a predetermined target gas pressure before injection in a state where the hydraulic fluid is supplied from the hydraulic fluid supply device to the accumulator in a molding cycle, wherein
the accumulator comprises a piston for separating the hydraulic fluid and gas, and
the control device sets the target gas pressure before injection based on the target value of the final pressure which is input.

2. The injection device according to claim 1 , wherein the control device calculates a pressure P B as the target gas pressure before injection by entering the target value of the final pressure which is input for a pressure P C in a numerical formula in which a pressure P X obtained by a numerical formula converting the pressure P C which the plunger receives from the molding material to the pressure P X of a gas chamber of the accumulator is entered for a pressure P A in a numerical formula calculating the pressure P B of the gas chamber at the time when a hydraulic fluid having a volume V U is supplied to the accumulator having the pressure P A of the gas chamber.

3. The injection device according to claim 1 , wherein
the control device
enters the target value of the final pressure which is input for a pressure P C in a numerical formula converting the pressure P C which the plunger receives from the molding material to a pressure P X of a gas chamber of the accumulator to calculate the pressure P X as a target gas pressure after injection and
sets the target gas pressure before injection of the next molding cycle based on that calculated target gas pressure after injection and a detection value of the pressure sensor after injection.

4. The injection device according to claim 1 , wherein
the control device
enters a detection value of the pressure sensor in a state where the hydraulic fluid is wholly discharged from the accumulator for a pressure P X in a numerical formula converting the pressure P X of a gas chamber in the accumulator to a pressure P C which the plunger receives from the molding material to calculate the pressure P C as the minimum final pressure and
judges whether the target value of the final pressure which is input is the minimum final pressure or more.

5. The injection device according to claim 1 , wherein
the control device
enters a value which is input from the input device or a constant value which the control device holds for a pressure P B in a numerical formula in which a pressure P A obtained by a numerical formula calculating the pressure P A based on the pressure P B in case where the pressure P B of a gas chamber becomes the pressure P A due to discharge of the hydraulic fluid of a volume V U from the accumulator is entered for a pressure P X in a numerical formula converting the pressure P X of the gas chamber of the accumulator to a pressure P C which the plunger receives from the molding material to calculate the pressure P C as a maximum final pressure, and
judges whether the target value of the final pressure which is input is the maximum final pressure or less.

6. The injection device according to claim 1 , wherein
the hydraulic fluid supply device has
a pump for supplying the hydraulic fluid to the accumulator and
a control valve for permitting or prohibiting the flow of the hydraulic fluid from the pump to the accumulator, and

the control device controls the hydraulic fluid supply device so that the flow of the hydraulic fluid from the pump to the accumulator is prohibited by the control valve at the time when the detection value of the pressure sensor reaches the target gas pressure before injection in a state where the hydraulic fluid is supplied from the pump to the accumulator in the molding cycle.

7. A molding apparatus comprising an injection device according to claim 1 .

Assignees

• Toshiba Machine Co Ltd

Inventors

• Tomioka Satoshi
• Nakata Ryusuke

Classifications

• B29C45/531

  Drive means therefor · CPC title

• B22D17/32

  Controlling equipment · CPC title

• B22D17/2015

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

• B22D17/203 Primary

  Injection pistons (B22D17/2053 takes precedence; for plastics B29C45/53) · CPC title

• B29C45/82

  Hydraulic {or pneumatic} circuits · CPC title