Injection molding machine, injection molding apparatus, and injection molding method

Patent metadata

Field	Value
Publication number	US-11660794-B2
Application number	US-202117452085-A
Country	US
Kind code	B2
Filing date	Oct 25, 2021
Priority date	Nov 16, 2020
Publication date	May 30, 2023
Grant date	May 30, 2023

Abstract

An injection molding machine that contributes to improving the quality of a workpiece is provided. An injection molding machine configured to causes torpedo pistons to be slid in one way to thereby plasticize a resin material supplied to a first space of a cylinder, and causes a molten resin to flow into a second space of the cylinder and causes the torpedo pistons to be slid in the other way to thereby inject the molten resin. The injection molding machine includes pressurizing pistons inserted into the torpedo pistons so that the pressurizing pistons can be slid in such a way that an amount of protrusion of the cylinder into the second space of the cylinder with respect to the torpedo pistons is changed, and energizing means for energizing the pressurizing pistons toward the second space of the cylinder.

First claim

What is claimed is:

1. An injection molding machine configured to cause a torpedo piston to slide inside a cylinder toward an opposite side of the cylinder to which an injection part is fixed to thereby plasticize a resin material supplied to a first space in the cylinder arranged on the side of the cylinder opposite to the side of the cylinder close to the injection part with the torpedo piston interposed therebetween among spaces of the first space and a second space in the cylinder arranged on the side of the cylinder close to the injection part, and to cause a molten resin to flow into the second space in the cylinder, and cause the torpedo piston to be slid toward the injection part inside the cylinder to thereby inject the molten resin from the injection part, the injection molding machine comprising:
a pressurizing piston that is inserted into a sliding part formed in the torpedo piston so that the pressurizing piston can be slid in an axial direction of the cylinder in such a way that an amount of protrusion of the piston into the second space with respect to the torpedo piston is changed, and
energizing means for energizing the pressurizing piston toward the second space of the cylinder with respect to the torpedo piston, wherein
the pressurizing piston has a bottomed cylindrical shape with an end on the injection part side closed, an outer diameter thereof being equal to the inner diameter of the torpedo piston, and is inserted into the torpedo piston,
the energizing means is made of an elastic body and is disposed inside the pressurizing piston, and when the torpedo piston is moved inside the cylinder to the opposite side of the cylinder to which the injection part is fixed in order to plasticize the resin material, the energizing means energizes the pressurizing piston in such a way that an amount of increase in the volume of the second space of the cylinder becomes equal to or smaller than an amount of decrease in the volume of the first space of the cylinder; and
as the pressure of the molten resin flowing into the second space of the cylinder rises, when a force pushing the pressurizing piston in the opposite side to the injection part side exceeds a force of the energizing means by which the pressurizing piston is energized, the pressurizing piston is pushed in the opposite side to the injection part side.

2. The injection molding machine according to claim 1 , comprising:
a drive part that slides the torpedo piston inside the cylinder by moving a rod connected to the torpedo piston in an axial direction of the cylinder, wherein
an outer cross section diameter of the pressurizing piston is equal to or larger than a cross section diameter of the rod, and
the volume of the second space in a state in which the torpedo piston is arranged on a side of the cylinder opposite to a part of the cylinder closest to the injection part in order to inject the molten resin and the pressurizing piston is arranged in the second space of the cylinder is equal to or smaller than the volume of the first space in a state in which the torpedo piston is arranged in a part of the cylinder closest to the injection part in order to plasticize the resin material and the rod is arranged in the first space of the cylinder.

3. The injection molding machine according to claim 1 , wherein a groove part as an enter part which the molten resin enters is formed in an end part of the pressurizing piston on a side of the pressurizing piston close to the injection part.

4. The injection molding machine according to claim 1 , comprising:
a plurality of cylinders;
a plurality of torpedo pistons that are slid inside the respective cylinders;
a plurality of pressurizing pistons inserted into sliding parts of the respective torpedo pistons in such a way that the pressurizing pistons can be slid;
a plurality of energizing means for energizing each of the pressurizing pistons inside each of the plurality of cylinders against the torpedo piston towards the second space of the cylinder; and
a plurality of drive parts configured to drive the respective torpedo pistons,
wherein the plurality of drive parts are controlled in such a way that a period during which a molten resin is injected from at least a first cylinder of the plurality of cylinders overlaps a period during which a molten resin is injected from a second cylinder of the plurality of cylinders for a preset period and that the molten resin is continuously injected from the plurality of cylinders.

5. An injection molding apparatus comprising:
the injection molding machine according to claim 1 ;
a valve connected to the cylinder and configured to block and release gas from entering the first space of the cylinder from the outside of the cylinder; and
a supply part configured to supply the resin material to the first space based on the flow of gas flowing into the first space of the cylinder from the outside of the cylinder when the valve is released.

6. The injection molding apparatus according to claim 5 , comprising a robot arm connected to the injection molding machine.

7. An injection molding method for causing a torpedo piston to be slid inside a cylinder to an opposite side of the cylinder to which an injection part is fixed inside the cylinder to thereby plasticize a resin material supplied to a first space in the cylinder arranged on the side of the cylinder opposite to the side of the cylinder close to the injection part with the torpedo piston interposed therebetween among spaces of the first space and a second space in the cylinder arranged on the side of cylinder close to the injection part, and to cause a molten resin to flow into the second space in the cylinder and cause the torpedo piston to be slid toward the injection part inside the cylinder to thereby inject the molten resin from the injection part,
wherein a pressurizing piston inserted into the torpedo piston so that it can be slid, having a bottomed cylindrical shape with an end on the injection part side closed, and having an outer diameter equal to the inner diameter of the torpedo piston is caused to protrude toward the second space of the cylinder by an elastic body arranged inside the pressurizing position in such a way that an amount of increase in the volume of the second space of the cylinder becomes equal to or smaller than an amount of decrease in the volume of the first space of the cylinder when the torpedo piston moves toward the side of the cylinder opposite to the side of the cylinder close to the injection part in order to plasticize the resin material; and
as the pressure of the molten resin flowing into the second space of the cylinder rises, when a force pushing the pressurizing piston in the opposite side to the injection part side exceeds a force energizing the pressurizing piston by the energizing means, the pressurizing piston is pushed in the opposite side to the injection part side.

8. The injection molding method according to claim 7 , comprising causing a plurality of torpedo pistons to be slid inside respective cylinders to cause a period during which the molten resin is injected from at least a first cylinder of the plurality of cylinders to overlap a period during which the molten resin is injected from a second cylinder of the plurality of cylinders for a first preset period, and continuously injecting the molten resin from the plurality of cylinders.

9. The injection molding method according to claim 8 , comprising causing, in each of the cylinders, a period during which the molten resin is injected to overlap a period during which the resin material is supplied to the cylinder for a second preset period.

10. The injection molding method according to claim 7 , comprising suppl

Assignees

• Toyota Motor Co Ltd

Inventors

• Yamamoto Yasuhiro

Classifications

• B29C45/535 Primary

  using two or more cooperating injection rams, e.g. coaxially or alternately operating rams · CPC title

• B29C2945/76531

  Temperature · CPC title

• B29C64/106

  using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material · CPC title

• B29C45/586

  Injection or transfer plungers · CPC title

• B29C45/07

  using movable injection units · CPC title