JP4763081B1 - Injection molding machine having weighing back pressure setting means - Google Patents

Abstract

To provide an injection molding machine having a measuring back pressure setting means capable of setting an appropriate back pressure even when there is no back pressure data in a database or when a recommended value of a resin manufacturer is not known.
SOLUTION: Back pressure Bp is set as an initial value of back pressure (SA100), manual weighing is started in a state where the nozzle is separated from the mold, it is determined whether or not a predetermined time has elapsed, and the predetermined time After the elapse of time, it is determined whether or not the screw is lowered to the measuring position (SA101 to SA103). An injection molding machine provided with a metering back pressure setting means for setting the back pressure Bp of molding conditions when the molten resin is discharged and does not fall to the metering position (SA104 to SA106).
[Selection] Figure 2

Description

  The present invention relates to an injection molding machine, and more particularly to an injection molding machine having a metering back pressure setting means.

  The injection molding machine injects resin melted by heating in a heating cylinder at a high pressure, fills the cavity space in the mold apparatus, and cools and solidifies in the cavity space. Take out from inside the mold.

  The injection molding machine includes a mold device, a mold clamping device, and an injection device. The mold apparatus includes a fixed mold and a movable mold, and the mold clamping apparatus includes a fixed platen and a movable platen, and the mold is closed by advancing and retracting the movable platen by driving a mold clamping motor. Perform mold clamping and mold opening.

  The injection device includes the heating cylinder that heats and melts the resin supplied from the hopper, and the injection nozzle that injects the molten resin, and the screw is disposed in the heating cylinder so that the screw can advance and retreat. Established.

  When the screw is rotated by driving the metering motor during the weighing process, the resin is weighed, and the resin is collected in front of the cylinder by the screw in the heating cylinder, and by driving the injection motor during the injection process. When the screw is advanced, the molten resin collected in the front is filled from the injection nozzle into the cavity space of the mold apparatus in a state where the mold clamping is performed.

  Then, when the molten resin in the cavity space is cooled and the mold is opened, the ejector motor of the ejector device is driven, the ejector pin is advanced, and the molded article is ejected and separated. Typed.

  By automatically operating the injection molding machine, setting of molding conditions such as back pressure for measuring the resin in the measuring step, in other words, setting of the measurement, is performed when continuously molding the molded product. When the screw is rotated, the resin is carried forward of the cylinder. As a result, the screw is pushed backward and lowered backward. At this time, push the screw forward so that the screw does not fall back. This force is called back pressure. Without this back pressure, air would be mixed into the resin in the cylinder.

  In the conventional back pressure setting method, it is often set to 3 Mpa, 5 Mpa, etc. uniformly based on the experience of the operator, the recommended value of the resin manufacturer, etc., regardless of the type of resin and the resin biting state. . However, since the appropriate value of the back pressure setting varies depending on the type of resin, the resin biting state, etc., the back pressure setting uniformly set in this way may not be appropriate.

  For example, if the back pressure setting is low, the resin density in the cylinder will be low, causing bubbles and silver. Conversely, if the back pressure setting is high, the resin density in the cylinder will be high and shear heat will be generated. In some cases, burns due to the occurrence of burns are caused, and molding defects are often caused because the back pressure is not set appropriately.

  When such a molding defect occurs, the back pressure setting is adjusted. Therefore, it has been desired to find an appropriate back pressure setting method.

  In Patent Document 1, molding conditions (back pressure, screw rotation speed, cylinder temperature, etc.) corresponding to the type of resin are stored as a database, and when the type of resin is specified, the molding conditions are read and the back pressure and the like are stored. A technique for automatic setting is disclosed.

Japanese Patent Laid-Open No. 2-147226

However, the technique disclosed in Patent Document 1 has a problem that it cannot cope with the type of resin not stored in the database.
Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to provide a measurement back pressure setting means capable of setting an appropriate back pressure even when there is no back pressure data in the database or when the recommended value of the resin manufacturer is not known. An injection molding machine is provided.

  In the invention according to claim 1 of the present application, in the injection molding machine, the weighing control means for measuring by the set back pressure with the nozzle opened, and the measuring operation is completed to the measuring position within a predetermined time when the measurement is performed. Measuring operation completion determining means for determining whether or not to perform measurement, performs measurement with the set back pressure as the first predetermined pressure, determines whether or not the measuring operation is completed up to the measuring position within a predetermined time, and If the weighing operation is completed up to the measuring position within the predetermined time, the second predetermined pressure is added to the set back pressure to measure the new set back pressure, and the weighing operation is completed to the measuring position within the predetermined time. Injecting molding having a weighing back pressure setting means characterized in that the set back pressure when the screw does not move back to the weighing position within a predetermined time is set as the back pressure at the time of weighing. Machine.

  According to the present invention, it is possible to provide an injection molding machine having a weighing back pressure setting means capable of setting an appropriate back pressure even when there is no back pressure data in the database or when a recommended value of a resin manufacturer is not known.

It is the schematic of the injection molding machine which is embodiment of this invention. It is a flowchart which shows the algorithm of this invention which sets a back pressure.

FIG. 1 is a schematic view of an injection molding machine according to an embodiment of the present invention. Reference numeral M denotes an injection molding machine. Reference numeral Mc denotes a mold clamping part, reference numeral Mi denotes an injection part, and reference numeral Mb denotes a machine base. Injection molding machine M is provided with a clamping portion _Mc, and injection unit Mi on a machine base Mb.

  The mold clamping portion Mc includes a movable platen forward / reverse motor 20 for moving the movable platen 23 back and forth, a rear platen 21, an ejector forward / backward motor 22 for ejecting an ejector pin for pushing a molded product out of the mold, a movable platen 23, a tie bar 24, and a fixed plate. A platen 25, a toggle mechanism 33, and an ejector mechanism 34 are provided. The rear platen 21 and the fixed platen 25 are connected by a plurality of tie bars 24, and the movable platen 23 is disposed so as to be guided by the tie bars 24. A movable mold is attached to the movable platen 23 and a fixed mold 32 is attached to the fixed platen 25.

  The injection part Mi includes a cylinder 27, a hopper 28 for supplying resin pellets into the cylinder 27, a hopper shutter 29 for blocking the supply of resin from the hopper 28 into the cylinder 27, a screw rotation motor 30, a screw forward / reverse motor 31, A screw 26 that is rotated from the screw rotation motor 30 via a transmission mechanism is provided. These configurations are not different from conventional injection molding machines.

  The control device 1 is a control device that controls the injection molding machine M to control the production of a molded product. The processor 2 is connected via a bus 3 to a servo interface 4, a ROM 6 for storing system programs, a RAM 7 for temporarily storing data and various control programs, an input device interface 8 with a display device, and an input device 9 with a display device. Has been. The ROM 6 stores a processing program for setting the measured back pressure according to the present invention.

  A servo amplifier 5 is connected to the servo interface 4. The input device 9 with a display device is connected to the input device interface 8 with a display device. The input device 9 with a display device includes a touch panel type liquid crystal display and a keyboard. Various commands and various parameters can be set by the input device 9 with a display device. Various commands and parameters can be set by displaying various interface screens on the display screen of the touch panel type display device of the input device 9 with a display device.

  The processor 2 is a processor that controls the entire injection molding machine. Connected to the servo amplifier 5 are a movable platen forward / reverse motor 20, an ejector forward / reverse motor 22, a screw rotation motor 30, and a screw forward / backward motor 31. Although the servo amplifier 5 is shown as one in the figure, a servo amplifier is connected to each of the motors. Each servo motor includes a position / speed detector (not shown), and a position / speed detection signal is fed back to the control device 1.

  In performing the automatic operation, the injection molding machine M starts from a mold closing operation, and at that time, manual weighing, that is, manual weighing is performed. In the manual weighing, there is no molded product formed in the cavity space, and no back pressure is applied to the heating cylinder. Accordingly, the resin stored in front of the screw becomes rough, and if the resin is injected in the injection process in that state, it becomes impossible to fill the cavity space with a sufficient amount of resin, and the molded product. In other words, molding defects such as shorts occur.

  Therefore, in the embodiment of the present invention, the process for performing the measurement back pressure setting according to the present invention is performed before the automatic operation is started by operating the input device 9 with a display device. Manual metering in the present invention is started in a state where the nozzle 35 attached to the tip of the cylinder 27 shown in FIG. The reason why the manual measurement is performed by separating the nozzle 35 from the mold 32 is to prevent the molten resin from being filled in the mold cavity in the measurement back pressure setting process according to the present invention. In the measurement back pressure setting, the molten resin discharged from the nozzle 35 is collected in a container (not shown).

FIG. 2 is a flowchart showing the algorithm of the present invention for setting the back pressure. Hereinafter, it demonstrates according to each step.
[Step SA100] The back pressure Bp is set as the initial value of the back pressure.
[Step SA101] Manual weighing is started with the nozzle away from the mold.
[Step SA102] It is determined whether or not a predetermined time has passed. When the predetermined time has passed, the process proceeds to Step SA103.
[Step SA103] It is determined whether or not the screw is lowered to the measurement position. If the screw is lowered to the measurement position, the process proceeds to Step SA104. If the screw is not lowered to the measurement position, the process proceeds to Step SA106.
[Step SA104] A value obtained by adding α to the back pressure Bp is set as a new back pressure Bp.
[Step SA105] The molten resin is discharged, and the process returns to Step SA101.
[Step SA106] The back pressure of the molding conditions is set to Bp, and the injection molding cycle is started.

1 Controller 2 Processor 3 Bus 4 Servo Interface 5 Servo Amplifier 6 ROM
7 RAM
DESCRIPTION OF SYMBOLS 8 Input device interface with a display device 9 Input device with a display device 20 Movable platen forward / reverse motor 21 Rear platen 22 Ejector forward / backward motor 23 Movable platen 24 Tie bar 25 Fixed platen 26 Screw 27 Cylinder 28 Hopper 29 Hopper shutter 30 Screw rotation motor 31 Screw Forward / backward motor 32 Mold 33 Toggle mechanism 34 Ejector mechanism 35 Nozzle M Injection molding machine Mb Machine base Mc Mold clamping part Mi Injection part

Claims (1)

In injection molding machine,
A weighing control means for weighing with a set back pressure with the nozzle open;
A weighing operation completion judging means for judging whether or not the weighing operation is completed up to the weighing position within a predetermined time when weighing is performed;
With
Weighing with the set back pressure as the first predetermined pressure, determine whether the weighing operation is completed to the weighing position within a predetermined time, and if the screw completes the weighing operation to the weighing position within the predetermined time, The second predetermined pressure is added to the pressure to measure as a new set back pressure, and it is repeatedly determined whether or not the weighing operation is completed up to the measuring position within the predetermined time. An injection molding machine having a measuring back pressure setting means, wherein a set back pressure when not retreating is set as a back pressure during measurement.

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