JPH046530B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field to Which the Invention Pertains> The present invention relates to a method for changing colors and resins in an injection molding machine.

<Conventional methods and their shortcomings> As the work of changing colors and resins in injection molding machines has increased significantly, the non-productive time required for the above-mentioned color changes and resin changes has increased, causing a decline in the operating rate. Processing profits are being squeezed due to an increase in resin and material losses, as well as a decline in production efficiency.

Conventional resin and color changing methods involve repeatedly measuring and purging the new resin to be used at the nozzle's retraction limit. However, with this method, resin and color changes were insufficient, and old resin and color often came out during start-up or during production operation.

Failures in resin replacement and color change are mainly classified into those that accumulate inside the screw barrel, the screw head, and the inner wall of the nozzle.

<Purpose of the Invention> The present invention eliminates the above-mentioned drawbacks, purges the resin accumulated in the screw barrel, the screw head, and the inner wall of the nozzle using a purging method according to the accumulated location, thereby reducing the time required for resin change and color change. The purpose is to significantly reduce the amount of resin required for resin changes and color changes, and to enable factories with improved yields and productivity.

<Summary of the Invention> In order to achieve the above object, the heating cylinder is continuously rotated at an arbitrary number of rotations to supply new resin into the heating cylinder and discharge old resin from the nozzle. The old resin inside is completely replaced with new resin. After closing the nozzle port and rotating the screw under arbitrary back pressure to measure a predetermined amount of resin,
Due to the second operation of unclosing the nozzle port and purging at a desired speed, the inside of the screw barrel becomes high pressure, and this high pressure causes residual gas to remain locally inside the screw groove, especially in the compression area. Eliminate resin. Furthermore, in the third operation, the nozzle opening is kept open and the screw is rotated under low back pressure to measure and purge a predetermined amount of resin, or the screw is moved back without rotating and then the screw is rotated for an arbitrary period of time. is rotated to measure and purge a predetermined amount of resin to remove residual resin downstream from the screw tip, particularly around the screw head nozzle.
The operating conditions for performing two or more of these three operations effective for automatic color change and resin change are as follows:
Measuring stroke or metering time, screw rotation speed,
Screw back pressure, injection speed, injection time, barrel temperature, duration of each operation or number of repeated rotations, etc. are stored in advance in the memory of the control device, and at the end of each operation, the operating conditions for the next operation are automatically set. This is an automatic color change and resin change method for injection molding machines.

<Embodiment> Next, an embodiment of the present invention will be described with reference to FIG. 1. Reference numeral 1 indicates a hopper for supplying raw materials attached to the heating cylinder 2, numeral 3 a heater for controlling the temperature of the heating cylinder 2, and numeral 4 a heating cylinder. This screw is inserted into the screw 2 and is moved forward and backward by a hydraulic cylinder 5, and rotated by a hydraulic motor 6. 7 is an electromagnetic directional control valve that connects the screw 4.
The injection is performed at position a, and the retraction operation is performed at position b. Reference numeral 8 designates an electromagnetic switching valve for controlling the metering process. When this valve is energized, the pressure oil from the hydraulic pump 9 acts on the hydraulic motor 6 to rotate the screw 4 and transfer the raw resin from the hopper 1 forward. Skrill 4 himself retreats. hydraulic cylinder 5
The hydraulic oil discharged from the electromagnetic proportional relief valve 10
When the set pressure is reached, the pressure oil is discharged to the tank 11. Reference numeral 12 denotes an electromagnetic proportional flow rate adjusting valve which controls the injection speed during the injection process when the switching valve 7 is switched to position a, and controls the screw rotation speed during the metering process when the switching valve 8 operates. Reference numeral 13 is an electromagnetic relief valve for controlling injection pressure or screw driving pressure. A sequencer 14 controls sequence operations and has a counting function to count the duration or number of operations of color change and resin change. 15 is a process controller that controls the electromagnetic proportional valves 10, 12, 13 and the heater 3, and controls the metering stroke or metering time, barrel temperature, screw rotation speed, screw back pressure, injection speed, injection time, etc., color change, resin change, etc. Input the operating conditions for the entire operation from a setting device (not shown),
It is something to control. Reference numeral 16 denotes a nozzle touch plate, which crosses the extension line connecting the tip of the heating cylinder 2 and the gate 19 of the mold 18 and reaches the notch 21 of the fixed plate 20 only during the color change and resin change process using a pneumatic or hydraulic cylinder 17. The nozzle opening is closed to prevent the tip of the heating cylinder 2 from being inserted. The operation of the nozzle touch plate 16 is optimal if it is operated in conjunction with other resin changing and color changing operations, for example, by the sequencer 14.

Next, to explain the operation, the sequencer 14 operates the switching valve 8 to continuously rotate the screw 4 for a specified time to supply new resin into the screw barrel, and the first operation until the nozzle is closed. After pressing the entire injection device against the nozzle touch plate 16 by a moving device (not shown), the switching valve 8 is operated to rotate the screw under the back pressure set by the electromagnetic proportional relief valve 10, and a predetermined amount of the injection device is released. Weigh the resin. After metering is complete, move the entire injection device back and remove the nozzle touch plate 1.
The second operation involves opening the nozzle from 6 and switching the switching valve 7 to position a to move the screw 4 forward and purging resin etc. from the nozzle, and switching the switching valve 7 to position b while leaving the nozzle open to move the screw 4 forward. After retreating without rotating, the switching valve 8 is operated to rotate the screw to measure a predetermined amount of resin. Next, each sequence operation of a third operation in which the switching valve 7 is set to the a position and the resin is purged from the nozzle in the same manner as the second operation is programmed. The process controller 15 also controls the set values of the electromagnetic proportional valves 10, 12, and 13 and the heater for the first, second, and third operations for each resin combination for each resin change or for each color combination for each color change. No. 3 temperature established values have been determined and registered in advance through trial and error. Furthermore, when performing a color change or resin change operation, specify which of the first, second, and third operations to use, and the number of repetitions and duration of each operation. It has a program area.

Therefore, in order to change the color or resin, first, each setting value of the initial operation mode set in the process controller 15 is set to the heater 3 and the electromagnetic proportional valve 1.
Sent to 0, 12, 13. As a result of heater control,
The detected value 3a is fed back to the process controller 15. When the temperature falls within the set temperature range, an operation start signal 15a is sent to the sequencer 14, and the first color change and resin change operations are started. When the operation for the specified time or number of times is completed, a completion signal is sent to the process controller 15, and the next operation mode is started.Each set value is first sent from the process controller 15, and the operation is the same as the first operation mode. is repeated. In this manner, when all operations initially programmed in the process controller 15 are completed, the color change and resin change steps are completed, and the next operation is automatically performed.

<Effects> With the method explained above, the time required for color change and resin change can be reduced to 1/2 to 1/3 of the conventional time, and the amount of color change and resin change can be reduced to 1/3 to 1/5 of the conventional amount, resulting in improved yield. , it became possible to improve productivity.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention. 2...Heating tube, 3...Heater, 4...Screw, 5...Hydraulic cylinder, 6...Hydraulic motor,
7, 8...Solenoid switching valve, 9...Hydraulic pump, 1
0, 13...Solenoid proportional relief valve, 12...Solenoid proportional flow adjustment valve, 14...Sequencer, 15...
Process controller, 16... nozzle touch plate, 20... fixing plate.

Claims (1)

[Scope of Claims] 1. When changing the color change resin, the screw is continuously rotated at a desired rotation speed to discharge the resin accumulated in the screw head, screw barrel, and inner wall of the nozzle of the injection device, and the new resin is heated into the heating tube. The first operation is to supply the old resin into the interior and discharge the old resin from the nozzle,
The nozzle port is closed by a mold or a nozzle port closing block that replaces the mold, and the screw is rotated under an arbitrary back pressure to measure a predetermined amount of resin, and then the nozzle port is unclosed and purge is performed at an arbitrary speed. 2 actions,
Color change and resin change operations are performed by combining two or more of the third operation of purging after measuring a predetermined amount of resin by rotating the screw under low back pressure with the nozzle opening open. In the control method, the operating conditions of the injection molding machine required for each operation, such as the metering stroke or metering time, screw rotation speed, screw back pressure, injection speed, injection time, barrel temperature, and the duration or number of repetitions of each operation, etc. An automatic color change for an injection molding machine, which is stored in advance in a storage unit of a control device, and is automatically switched to the operating conditions for the next operation at the end of each operation.
How to change resin. 2. When changing the color change resin, the screw is continuously rotated at a desired speed to discharge the resin accumulated on the screw head, screw barrel, and inner wall of the nozzle of the injection device, and the new resin is supplied into the heating cylinder and the old resin is removed. The first operation of discharging from the nozzle,
The nozzle port is closed by a mold or a nozzle port closing block that replaces the mold, and the screw is rotated under an arbitrary back pressure to measure a predetermined amount of resin, and then the nozzle port is unclosed and purge is performed at an arbitrary speed. 2 actions,
Color change, resin, performed by combining two or more of each operation of the third operation, in which the nozzle opening is left open, the screw is moved back without rotating, the screw is rotated for an arbitrary period of time, a predetermined amount of resin is measured, and the third operation is purged. In the changing operation control method, the metering stroke or metering time, which is the operating condition of the injection molding machine necessary for each operation,
Screw rotation speed, screw back pressure, injection speed, injection time, barrel temperature, and the duration or number of repetitions of each operation are stored in advance in the memory of the control device, and the next operation is automatically performed at the end of each operation. An automatic color change and resin change method for an injection molding machine characterized by switching to operating conditions.