US-20260124797-A1 - Injection Molding Machine, Injection Device, and Method of Controlling Injection Molding Machine

US20260124797A1US 20260124797 A1US20260124797 A1US 20260124797A1US-20260124797-A1

Abstract

An injection molding machine heats an injection nozzle using, as a target temperature, a detected temperature of a synchronization zone, when a detected temperature of the injection nozzle is lower than a nozzle reference temperature. The injection molding machine heats the injection nozzle using a nozzle set temperature as a target temperature, when a detected temperature of the injection nozzle is higher than the nozzle reference temperature.

Inventors

Megumi Otani
Naoyuki Seishin
Tomoki Masuda

Assignees

THE JAPAN STEEL WORKS, LTD.

Dates

Publication Date: 20260507
Application Date: 20250913
Priority Date: 20240927

Claims (20)

1 . An injection molding machine comprising: an injection device that melts and injects an injection material; a mold clamping device that clamps a mold into which the injection material has been injected; and a controller that controls the injection device, wherein the injection device includes: a cylinder; a screw that is placed in the cylinder and heats the injection material into a molten material; a nozzle that is placed at a distal end of the cylinder and injects, into the mold, the molten material generated by heating; a nozzle temperature sensor that detects a temperature of the nozzle; a cylinder temperature sensor that detects a temperature of the cylinder; and a heating device that is controlled by the controller and configured to heat the nozzle and the cylinder independently of each other, and the controller is configured to control the temperature of the nozzle based on the temperature detected by the cylinder temperature sensor, so as not to exceed the temperature of the cylinder.
2 . The injection molding machine according to claim 1 , wherein the cylinder temperature sensor is configured to detect a temperature of a predetermined portion of the cylinder, a temperature increase rate of the nozzle is faster than a temperature increase rate of the predetermined portion, the controller is configured to control the heating device such that the temperature of the nozzle is caused to be a nozzle set temperature, a nozzle reference temperature is defined as a temperature determined by subtracting a nozzle predetermined temperature from the nozzle set temperature, and in order to prevent the temperature of the nozzle from exceeding the temperature of the cylinder, the controller is configured to heat the nozzle using the temperature of the predetermined portion detected by the cylinder temperature sensor as a target temperature, when the temperature of the nozzle is lower than the nozzle reference temperature, and heat the nozzle using the nozzle set temperature as the target temperature, when the temperature of the nozzle is higher than the nozzle reference temperature.
3 . The injection molding machine according to claim 2 , wherein the cylinder is divided into a plurality of zones in a direction in which the cylinder extends, the heating device is configured to individually heat the plurality of zones, and the predetermined portion is a portion corresponding to a zone that is larger in heat capacity than the nozzle among the plurality of zones.
4 . The injection molding machine according to claim 3 , wherein the predetermined portion is a zone that is largest in heat capacity among the plurality of zones.
5 . The injection molding machine according to claim 4 , wherein the plurality of zones include: a connection zone to which the nozzle is connected; and an adjacent zone adjacent to the connection zone, and the predetermined portion is the adjacent zone.
6 . The injection molding machine according to claim 2 , wherein the controller is configured to use a nozzle proportional gain to control the heating device, and the nozzle predetermined temperature is set to fall within a predetermined range including a reciprocal of the nozzle proportional gain.
7 . The injection molding machine according to claim 6 , wherein the nozzle predetermined temperature is the reciprocal of the nozzle proportional gain.
8 . The injection molding machine according to claim 2 , wherein the controller is configured to control the heating device such that the temperature of the predetermined portion is caused to be a cylinder set temperature, a cylinder reference temperature is defined as a temperature determined by subtracting a cylinder predetermined temperature from the cylinder set temperature, and the controller is configured to heat the nozzle using the temperature of the predetermined portion as a target temperature, when the temperature of the nozzle is lower than the nozzle reference temperature and the temperature of the predetermined portion is lower than the cylinder reference temperature.
9 . The injection molding machine according to claim 8 , wherein the controller is configured to cause the nozzle to be heated using the nozzle set temperature as the target temperature, when the temperature of the nozzle is lower than the nozzle reference temperature and the temperature of the predetermined portion is higher than the cylinder reference temperature.
10 . The injection molding machine according to claim 8 , wherein the controller is configured to use a cylinder proportional gain to control the heating device heating the predetermined portion, and the cylinder predetermined temperature is set to fall within a predetermined range including a reciprocal of the cylinder proportional gain.
11 . The injection molding machine according to claim 10 , wherein the cylinder predetermined temperature is the reciprocal of the cylinder proportional gain.
12 . An injection device comprising: a cylinder; a screw that is placed in the cylinder and heats an injection material into a molten material; a nozzle that is placed at a distal end of the cylinder and injects, into a mold, the molten material generated by heating; a nozzle temperature sensor that detects a temperature of the nozzle; a cylinder temperature sensor that detects a temperature of the cylinder; and a heating device configured to heat the nozzle and the cylinder independently of each other, wherein the temperature of the nozzle is controllable so as not to exceed the temperature of the cylinder, based on the temperature detected by the cylinder temperature sensor.
13 . A method of controlling an injection molding machine, the injection molding machine comprising: an injection device that melts and injects an injection material; and a mold clamping device that clamps a mold into which the injection material has been injected; the injection device including: a cylinder; a screw that is placed in the cylinder and heats the injection material into a molten material; and a nozzle that is placed at a distal end of the cylinder and injects, into the mold, the molten material generated by heating, the method comprising: (a) controlling, based on a temperature of the cylinder, a temperature of the nozzle so as not to exceed the temperature of the cylinder.
14 . The method of controlling the injection molding machine according to claim 13 , wherein a temperature increase rate of the nozzle is faster than a temperature increase rate of a predetermined portion of the cylinder, a nozzle reference temperature is defined as a temperature determined by subtracting a nozzle predetermined temperature from a nozzle set temperature for the nozzle, and in order to prevent the temperature of the nozzle from exceeding the temperature of the cylinder, the (a) controlling the temperature of the nozzle includes: (b) heating the nozzle using a temperature of the predetermined portion as a target temperature, when the temperature of the nozzle is lower than the nozzle reference temperature; and (c) heating the nozzle using the nozzle set temperature as the target temperature, when the temperature of the nozzle is higher than the nozzle reference temperature.
15 . The method of controlling the injection molding machine according to claim 14 , wherein the cylinder is divided into a plurality of zones in a direction in which the cylinder extends, the method comprises heating the plurality of zones individually, and the predetermined portion is a portion corresponding to a zone that is larger in heat capacity than the nozzle among the plurality of zones.
16 . The method of controlling the injection molding machine according to claim 15 , wherein the predetermined portion is a zone that is largest in heat capacity among the plurality of zones.
17 . The method of controlling the injection molding machine according to claim 16 , wherein the plurality of zones include: a connection zone to which the nozzle is connected; and an adjacent zone adjacent to the connection zone, and the predetermined portion is the adjacent zone.
18 . The method of controlling the injection molding machine according to claim 14 , wherein the method comprises using a nozzle proportional gain to heat the nozzle, and the nozzle predetermined temperature is set to fall within a predetermined range including a reciprocal of the nozzle proportional gain.
19 . The method of controlling the injection molding machine according to claim 18 , wherein the nozzle predetermined temperature is the reciprocal of the nozzle proportional gain.
20 . The method of controlling the injection molding machine according to claim 14 , wherein a cylinder reference temperature is defined as a temperature determined by subtracting a cylinder predetermined temperature from a cylinder set temperature for the predetermined portion, and the (a) controlling the temperature of the nozzle includes: (e) heating the nozzle using the temperature of the predetermined portion as the target temperature, when the temperature of the nozzle is lower than the nozzle reference temperature and the temperature of the predetermined portion is lower than the cylinder reference temperature of the predetermined portion.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This nonprovisional application is based on Japanese Patent Application No. 2024-168098 filed on Sep. 27, 2024 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION Field of the Invention The present disclosure relates to an injection molding machine, an injection device, and a method of controlling the injection molding machine. Description of the Background Art Japanese Patent Laying-Open No. 2006-240203 discloses an injection molding machine. This injection molding machine controls the temperature of the nozzle and the temperature of the cylinder by feedback control. SUMMARY OF THE INVENTION In the above-described injection molding machine, generally the volume of the nozzle is smaller than the volume of the cylinder, and furthermore, since a material to be injected is stored in the cylinder, the heat capacity of the cylinder is larger than the heat capacity of the nozzle. Therefore, when the same amount of heat is applied to the nozzle and the cylinder, the temperature increase rate of the nozzle is faster than the temperature increase rate of the cylinder. As such, when the temperature of the nozzle and the cylinder is raised in the injection molding machine, the timing at which the temperature of the nozzle reaches a set temperature is earlier than the timing at which the temperature of the cylinder reaches a set temperature. In this case, after the temperature of the nozzle reaches the set temperature, it is necessary to continue heating the nozzle in order to keep the temperature of the nozzle until the temperature of the cylinder reaches the set temperature. Accordingly, there may arise a problem that wasteful electric power is consumed in order to keep the temperature of the nozzle. The present invention has been made to solve such a problem, and an object of the present invention is to reduce electric power consumed when the temperature of the nozzle is raised. In the injection molding machine according to the present disclosure, the temperature of the nozzle is controlled, based on the temperature of the cylinder, so as not to exceed the temperature of the cylinder. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for illustrating a configuration of an injection molding machine according to the present embodiment. FIG. 2 is a diagram for illustrating a heating cylinder and an injection nozzle. FIG. 3 is a functional block diagram of a controller. FIG. 4 is a flowchart for illustrating a main process performed by the controller. FIG. 5 is a diagram showing simulation results according to the present embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present disclosure are hereinafter described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference characters, and a description thereof is not herein repeated. Configuration of Injection Molding Machine FIG. 1 is a diagram for illustrating a configuration of an injection molding machine 100 according to the present embodiment. For convenience of description, a floor surface on which injection molding machine 100 is placed is defined as XY plane, and the direction perpendicular to the floor surface is defined as Z-axis direction. The positive direction of the Z axis may be referred to as upper surface side or upper side, and the negative direction thereof may be referred to as lower surface side or lower side. Although injection molding machine 100 is shown as a horizontal injection molding machine, injection molding machine 100 is not limited to the horizontal injection molding machine but may be a vertical injection molding machine. Injection molding machine 100 includes a mold clamping device 110 for clamping a mold, an injection device 120 for melting and injecting an injection material, an operation panel 130, and a controller 140. In FIG. 1, mold clamping device 110 is located on the negative direction side of the X axis with respect to injection device 120. Mold clamping device 110 includes a bed 111, a stationary platen 112, a mold clamping housing 113, a movable platen 114, a tie bar 115, a mold clamping mechanism 116, molds 117 and 118, and a ball screw 119. Bed 111 is disposed on the floor surface, and devices such as stationary platen 112, mold clamping housing 113, and movable platen 114 are mounted on the upper surface of the bed. On bed 111, stationary platen 112 is fixed to the end relatively closer to injection device 120 (that is, the end on the positive direction side of the X axis). On bed 111, mold clamping housing 113 is disposed at the end on the negative direction side of the X axis. Stat