Die Cushion Controller Pressure Pattern for Overshoot Reduction
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Solution Overview
Problem
Existing die cushion controllers face challenges in quickly generating high cushion pressure while minimizing overshooting, which can lead to instability and poor molding precision due to fluctuations in pressure.
Innovation Solution
A die cushion controller with a pressure pattern that includes a low pressure target value followed by a complementary target value for a linear increase, allowing the cushion pressure to reach a high pressure target value with reduced overshooting, ensuring stable and precise pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pressure pattern is set to quickly reach a high target pressure from the time point at which the upper die contacts with the workpiece, then the cushion pressure can be generated quickly, but overshooting occurs causing cushion pressure to exceed the target pressure and subsequently converge down, resulting in fluctuations in pressure
Solution Approach 1:
The pressure pattern is segmented into three distinct target value phases: low pressure target value (initial contact phase), high pressure target value (workpiece holding phase), and complementary target value (transition phase with linear increase). This segmentation allows the system to optimize for speed during initial contact while ensuring precision during workpiece holding, eliminating the overshooting problem by providing a controlled transition path between pressure levels.
2Reliability
If the cushion pressure is increased rapidly to correspond to high target pressure, then the workpiece can be held securely, but overshooting causes the cushion pressure to exceed the target pressure to a large degree, resulting in deterioration in molding precision
Solution Approach 1:
The system performs preliminary action by first establishing the low pressure target value phase where the cushion pressure gently increases to an initial level. This preliminary phase prepares the system for the subsequent high pressure phase, ensuring that when the pressure transitions to the high target value, the system is already stabilized and ready, preventing overshooting while maintaining reliable workpiece holding.
Solution Approach 2:
The pressure pattern dynamically changes parameters by transitioning between low pressure target value, high pressure target value, and complementary target value phases. The complementary target value phase specifically uses a linear increase rate that is optimized to reach the high pressure target value without excessive overshooting, thereby maintaining both workpiece holding reliability and molding precision.
3Stability of the object's composition
If a free-form curve pressure pattern is used where cushion pressure starts to gently increase, then the pressure control is smooth, but the cushion pressure cannot quickly reach the predetermined target pressure required for secure workpiece holding
Solution Approach 1:
The pressure pattern is made dynamic by implementing three distinct phases with different characteristics: low pressure target value phase (gentle initial increase), complementary target value phase (linear increase with optimized rate), and high pressure target value phase (target pressure maintenance). This dynamic structure allows the system to adapt the pressure increase rate to the specific phase of operation, achieving both stability during transition and speed during workpiece holding.
Data Source
AI summary
Provided is a die cushion controller that controls an ascending/descending speed of a die cushion based on a predetermined pressure pattern 56. The pressure pattern 56 has a low pressure target value PL which is first followed by an increased cushion pressure, a high pressure target value PH corresponding to a requisite cushion pressure for retaining a workpiece, and a complementary target value PC which is followed by the cushion pressure at a substantially linear increase rate for a predetermined period of time T2 until the cushion pressure exceeds the low pressure target value PL and reaches the high pressure target value PH. The cushion pressure overshooting the low pressure target value PL continues to follow the complementary target value PC, so that an overshooting amount occurring at a time point at which the cushion pressure reaches the high pressure target value PH can be reduced. As a result, pressure variation in the cushion pressure can be suppressed.