Injection molding method

Patent metadata

Field	Value
Publication number	US-10464246-B2
Application number	US-201515113669-A
Country	US
Kind code	B2
Filing date	Apr 20, 2015
Priority date	Nov 14, 2014
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

An injection molding method includes: a plasticizing process of feeding a resin pellet and additive components to a heating cylinder including a screw that can rotate around a rotation axis and can advance and retreat along the rotation axis, and generating molten resin by rotating the screw in a normal direction; and an injection process of injecting to a cavity the molten resin containing the additive components. In the plasticizing process, retreat operation of forcibly retreating the screw is performed at a predetermined velocity by a predetermined stroke or a predetermined time.

First claim

The invention claimed is:

1. An injection molding method of resin containing reinforcing fibers, comprising:
a plasticizing process of feeding a fiber bundle and a resin raw material to a cylinder including a screw that can rotate around a rotation axis and can advance and retreat along the rotation axis, and generating molten resin by rotating the screw in a normal direction, the fiber bundle comprising the reinforcing fibers in a roving state or in a chopped strand state; and
an injection process of injecting to a cavity the molten resin containing the reinforcing fibers, wherein
in the plasticizing process;
a shear force in a direction different from a direction of a shear force generated by rotation of the screw is applied to the fiber bundle contained in the molten resin inside a groove of the screw by a retreat operation of forcibly retreating the screw for a predetermined stroke or for a predetermined time that can form a space in which the molten resin is not present, the space being formed at a side away from the screw, so that a swirling flow is generated in the molten resin containing the reinforcing fibers in a rotation axis direction of the screw; and
in the plasticizing process;
the retreat operation is performed after a cylinder downstream side of the screw is filled with the molten resin, and a rotation operation of rotating the screw in the normal direction is performed after the retreat operation, so that dispersion of the reinforcing fibers is promoted, wherein the rotation of the screw is stopped during the retreat operation.

2. An injection molding method of resin containing reinforcing fibers, comprising:
a plasticizing process of feeding a fiber bundle and a resin raw material to a cylinder including a screw that can rotate around a rotation axis and can advance and retreat along the rotation axis, and generating molten resin by rotating the screw in a normal direction, the fiber bundle comprising the reinforcing fibers in a roving state or in a chopped strand state; and
an injection process of injecting to a cavity the molten resin containing the reinforcing fibers, wherein
in the plasticizing process;
a shear force in a direction different from a direction of a shear force generated by rotation of the screw is applied to the fiber bundle contained in the molten resin inside a groove of the screw by a retreat operation of forcibly retreating the screw for a predetermined stroke or for a predetermined time that can form a space in which the molten resin is not present, the space being formed at a side away from the screw, so that a swirling flow is generated in the molten resin containing the reinforcing fibers in a rotation axis direction of the screw; and
in the plasticizing process;
the retreat operation is performed after a cylinder downstream side of the screw is filled with the molten resin, and a rotation operation of rotating the screw in the normal direction is performed after the retreat operation, so that dispersion of the reinforcing fibers is promoted,
wherein the retreat operation includes a first retreat operation and a second retreat operation, the space in which the molten resin is not present is formed by performing the first retreat operation, and the second retreat operation is performed after it is detected that the space has been filled with the molten resin by performing the rotation operation.

3. An injection molding method of resin containing reinforcing fibers, comprising:
a plasticizing process including a feeding operation of feeding a fiber bundle and a resin raw material to a cylinder including a screw that can rotate around a rotation axis and can advance the fiber bundle and the resin raw material along the rotation axis, and generating molten resin by rotating the screw in a normal direction, the fiber bundle comprising the reinforcing fibers in a roving state or in a chopped strand state;
a retreat operation of forcibly retreating the screw for a predetermined stroke or for a predetermined time so that a shear force in a direction different from a direction of a shear force generated by rotation of the screw in the feeding operation is applied to the fiber bundle contained in the molten resin inside a groove of the screw by retreating the screw, the retreat operation forming a space in which the molten resin is not present, the space being formed at a side away from the screw, the space being formed in an expanded manner by a lower pressure than an inside of the molten resin and the space being created by leakage of gas components containing a volatile component, so that a swirling flow is generated in the molten resin containing the reinforcing fibers in a rotation axis direction of the screw; and
a rotation operation of rotating the screw in the normal direction to convey the molten resin to a downstream side to compress the space with the molten resin so that dispersion of the reinforcing fibers is promoted, and

an injection process of injecting to a cavity the molten resin containing the reinforcing fibers.

4. The injection molding method according to claim 3 , wherein the resin raw material is fed from an upstream side of the cylinder and the fiber bundle is fed from a downstream side of the cylinder.

5. The injection molding method according to claim 3 , wherein the fiber bundle and the resin raw material are fed from the same feed hole of the cylinder.

6. The injection molding method according to claim 3 , wherein the shear forces include a shear force T 2 along the rotation axis direction of the screw and a shear force T 1 along a peripheral direction perpendicular to the rotation axis direction.

7. The injection molding method according to claim 6 , wherein in the retreat operation, the screw is forcibly retreated continuously or intermittently by diving the predetermined stroke or the predetermined time.

8. The injection molding method according to claim 3 , wherein the retreat operation and the rotation operation are alternately repeated.

9. The injection molding method according to claim 8 , wherein the retreat operation includes a first retreat operation and a second retreat operation, the space in which the molten resin is not present is formed by performing the first retreat operation, and the second retreat operation is performed after it is detected that the space has been filled with the molten resin by performing the rotation operation.

10. The injection molding method according to claim 9 , wherein a force in an advance direction is applied to the screw after the space is filled with the molten resin to thereby apply the force in the advance direction to the molten resin.

11. The injection molding method according to claim 10 , wherein the force in the advance direction is applied by rotating the screw in the normal direction to thereby convey the molten resin in the advance direction.

12. The injection molding method according to claim 8 , wherein the retreat operation includes a first retreat operation, the space in which the molten resin is not present is formed by performing the first retreat operation, and a force in an advance direction is applied to the molten resin after it is detected that the space has been filled with the molten resin by performing the rotation operation.

13. The injection molding method according to claim 3 , wherein the rotation operation is a rotation operation of rotating the screw while a position of the screw in a direction of the rotation axis is maintained, or the screw is advanced.

14. The injection molding method according to claim 3 , wherein in the plasticizing process, the retreat operation is performed, and an ad

Assignees

• U Mhi Platech Co Ltd
• Mitsubishi Heavy Ind Ltd

Inventors

• Nobuta Munehiro
• Toda Naoki
• Kariya Toshihiko
• Yamaguchi Takeshi
• Kinoshita Kiyoshi

Classifications

• B29C2945/76846

  Metering · CPC title

• B29C2945/76605

  rotational movement · CPC title

• B29C45/0005

  using fibre reinforcements · CPC title

• B29C2945/76665

  screw · CPC title

• B29C2945/76568

  Position · CPC title