Injection molding machine, additive manufacturing apparatus, and pressure control method

Patent metadata

Field	Value
Publication number	US-11911947-B2
Application number	US-202217655283-A
Country	US
Kind code	B2
Filing date	Mar 17, 2022
Priority date	Mar 30, 2021
Publication date	Feb 27, 2024
Grant date	Feb 27, 2024

Abstract

An injection molding machine includes a cylinder that accommodates a molten resin, a discharging nozzle, a piston that discharges the molten resin from the discharging nozzle, and one or more processors configured to execute the following functions. The functions include calculating a target pressure at which a flow rate of the molten resin discharged from the discharging nozzle becomes an indicated flow rate, controlling a pressure of the molten resin in the cylinder such that the pressure becomes the target pressure, acquiring a temperature of the molten resin in the cylinder, and acquiring a pseudo-plastic viscosity corresponding to the temperature of the molten resin. The target pressure is calculated based on the indicated flow rate, the temperature of the molten resin, the pseudo-plastic viscosity, and the size of the discharging nozzle.

First claim

What is claimed is:

1. An injection molding machine comprising:
a cylinder that accommodates a molten resin;
a discharging nozzle that is communicated with the cylinder;
a piston configured to discharge the molten resin from the discharging nozzle by sliding in the cylinder and pressurizing the molten resin in the cylinder; and
one or more processors configured to
calculate a target pressure that is a target value used for pressurizing the molten resin in the cylinder and at which a flow rate of the molten resin discharged from the discharging nozzle becomes an indicated flow rate;
acquire a temperature of the molten resin in the cylinder;
acquire a pseudo-plastic viscosity corresponding to the temperature of the molten resin;
control a pressure of the molten resin in the cylinder such that the pressure becomes the target pressure, the target pressure is calculated based on the indicated flow rate, the temperature of the molten resin, the pseudo-plastic viscosity, and a size of the discharging nozzle, the pressure of the molten resin is controlled by controlling a movement speed of the piston, and the controlling the movement speed of the piston is based on a bulk modulus of the molten resin; and
modify the bulk modulus only when a difference between a pressure change amount and the target pressure is equal to or higher than a predetermined value, the pressure change amount calculated from an actually measured pressure and a substantially pressurized volume,

wherein the substantially pressurized volume is calculated by subtracting an outflow rate multiplied by a predetermined interval of time from a volume that shrinks as the piston moves during the predetermined interval of time.

2. The injection molding machine according to claim 1 , wherein the one or more processors are configured to acquire the pseudo-plastic viscosity corresponding to a kind and the temperature of the molten resin.

3. The injection molding machine according to claim 2 , further comprising:
a memory that stores the pseudo-plastic viscosity for each kind and temperature of resins in advance, wherein
the one or more processors are configured to acquire, from the memory, the pseudo-plastic viscosity corresponding to the kind and the temperature of the molten resin.

4. The injection molding machine according to claim 1 , wherein the one or more processors are configured to execute feed-forward control of the movement speed of the piston using the bulk modulus of the molten resin.

5. The injection molding machine according to claim 4 , wherein the one or more processors are configured to further execute the feed-forward control of the movement speed of the piston that is calculated based on a predicted flow rate.

6. The injection molding machine according to claim 1 , wherein the piston is a torpedo.

7. The injection molding machine according to claim 1 , wherein a plurality of combinations of the cylinder and the piston is included in the injection molding machine.

8. An additive manufacturing apparatus comprising:
the injection molding machine according to claim 1 ,
wherein the additive manufacturing apparatus is configured to model a three-dimensional modeled object by laminating the molten resin discharged from the discharging nozzle.

9. The injection molding machine according to claim 1 , wherein the one or more processors are configured to modify the bulk modulus while the piston discharges the molten resin from the discharging nozzle.

10. The injection molding machine according to claim 1 , wherein the one or more processors are configured to modify the bulk modulus based on the actually measured pressure at a start of the predetermined interval of time.

Assignees

• Toyota Motor Co Ltd

Inventors

• Yamamoto Yasuhiro

Classifications

• B29C45/77 Primary

  of velocity or pressure of moulding material · CPC title

• B29C45/20

  Injection nozzles {(B29C45/1603 takes precedence)} · CPC title

• B29C45/30

  Flow control means disposed within the sprue channel, e.g. "torpedo" construction · CPC title

• B29C45/53

  using injection ram or piston · CPC title

• B29C45/7646

  viscosity · CPC title