Injection Molding Machine Control for Clamping Force and Drive Cycles
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Solution Overview
Problem
The processing load of the controller in injection molding machines is increased due to the simultaneous control of mold clamping force correction and motor positioning, which requires high response times and can lead to inefficiencies in the control cycle.
Innovation Solution
Implementing a control system where the monitoring control cycle for mold clamping force is longer than the drive control cycle, allowing for separate prioritization of high-priority drive controls and reducing processing load by prohibiting unnecessary detection signals during non-clamping states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-cavity mold is used to increase productivity, then the number of molded articles produced per cycle increases, but the mold weight increases requiring a larger injection molding machine
Solution Approach 1:
The mold is divided into a fixed mold portion and a movable mold portion, allowing the molded articles to be automatically ejected from the fixed portion by the movable portion. This segmentation enables multi-cavity production without proportionally increasing the overall mold weight, as each cavity is independently structured.
Solution Approach 2:
Multiple cavities are arranged within the mold structure in a nested configuration, allowing multiple molded articles to be produced simultaneously within a compact mold footprint. This nesting approach increases productivity while controlling mold weight by efficiently utilizing the available mold space.
2Productivity
If the clamping force is increased to handle heavier molds for multi-cavity production, then the mold can support more cavities, but the power consumption of the injection molding machine increases
Solution Approach 1:
The injection molding machine uses a variable speed drive for the injection plunger, allowing the injection speed and force to be dynamically adjusted during the molding cycle. This dynamic control enables efficient handling of multi-cavity molds without requiring excessive clamping force throughout the entire cycle, thereby reducing power consumption while maintaining high cavity count capability.
3Productivity
If the injection speed is increased to reduce cycle time, then productivity improves, but the risk of molded article defects increases
Solution Approach 1:
The injection process is divided into multiple stages with different injection speeds. The injection plunger operates at high speed during the filling phase to reduce cycle time, then transitions to low speed during the packing and holding phases to prevent defects. This periodic variation in injection speed maintains both high productivity and manufacturing precision.
Solution Approach 2:
The injection speed is dynamically controlled throughout the molding cycle, automatically adjusting between high and low speeds based on the filling stage. This dynamic speed control allows the system to achieve fast cycle times while preventing defects that would occur with consistently high injection speeds.
Data Source
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Figure 3(a)~3(b)
AI summary
An injection molding machine according to an aspect of an embodiment includes a drive unit which moves a movable unit and a controller which controls the drive unit, in which the controller performs a drive control of the drive unit and a monitoring control, and a control cycle of the monitoring control is longer than a control cycle of the drive control.