Press Forming Tool Strain Control Using Piezoelectric Sensors
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Solution Overview
Problem
Existing press-forming devices face challenges in accurately controlling tool strain during the forming process, particularly for tools with complex shapes, leading to inconsistencies in product quality and reduced control accuracy due to inadequate strain measurement and control methods.
Innovation Solution
A press-forming device equipped with strain amount measuring means and control means, which are strategically installed within the punch, die, and blank holder to directly measure and control tool strain, using piezoelectric sensors and actuators to maintain strain within predetermined ranges, thereby improving accuracy and applicability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If strain sensors are provided on the press machine beams (upper and lower beams) to detect beam strain, then the bending angle uniformity is improved, but the measurement precision of tool strain is insufficient for complex-shaped tools
Solution Approach 1:
The patent replaces conventional strain sensors with piezoelectric sensors that utilize the piezoelectric effect to detect tool strain. This substitution enables direct measurement of strain within the tool itself, providing higher measurement precision for complex-shaped tools compared to indirect beam strain measurement methods.
Solution Approach 2:
The patent introduces piezoelectric sensors as intermediary elements embedded within the tool structure. These sensors act as mediators that directly sense the strain state of the tool during forming, enabling accurate measurement of tool strain that cannot be obtained through beam strain sensors alone.
2Manufacturing precision
If multiple strain sensors and actuators are installed within the tool to directly measure and control strain, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The patent embeds piezoelectric sensors and actuators within the tool structure itself, nesting the measurement and control elements inside the punch, die, or blank holder. This integration approach achieves high manufacturing precision while minimizing the increase in device complexity by making the sensors and actuators part of the tool's internal structure.
Solution Approach 2:
The patent designs the tool structure to serve multiple functions: the tool performs both the forming function and houses the strain measurement and control systems. The punch, die, or blank holder simultaneously acts as the forming element and the mounting structure for piezoelectric sensors and actuators, reducing overall device complexity.
3Adaptability or versatility
If the press machine and tool conditions change, then the adaptability is improved, but the tool strain control accuracy deteriorates due to quality scatter
Solution Approach 1:
The patent implements a closed-loop feedback control system where piezoelectric sensors continuously monitor tool strain during forming, and the control unit adjusts actuator output in real-time to maintain strain within the predetermined range. This feedback mechanism ensures consistent quality across varying press machine and tool conditions by dynamically compensating for changes.
Solution Approach 2:
The patent employs dynamic strain control by continuously adjusting the actuator output based on real-time strain measurements. The control system dynamically adapts to changing forming conditions (press machine variations, tool wear, material properties) by modifying the blank holder force or punch position to maintain optimal tool strain levels throughout the forming process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device effectively controls tool strain, enhancing the dimensional accuracy and shape fixability of formed products, reducing quality variations and improving forming limits, even under varying conditions.
Implementation Method 1
using piezoelectric sensors and actuators to maintain strain within predetermined ranges
Data Source
Figure 1
Figure 2A~2C
Figure 3~4
AI summary
A press-forming device has a punch (2), a die (7) which relatively moves with respect to the punch (2), a strain amount measuring means (8) which is provided inside a member to be controlled and measures a strain amount of the aforesaid member to be controlled which occurs in accordance with press-forming, when at least one of the punch (2) and the die (7) is made the aforesaid member to be controlled, and a strain amount control means (9) which is provided in the aforesaid member to be controlled and controls the strain amount of the aforesaid member to be controlled which occurs in accordance with press-forming. The strain amount control means (9) controls a drive amount of the aforesaid member to be controlled so that the strain amount measured by the strain amount measuring means (8) is in a predetermined range during forming. Thereby, reduction in a surface strain, improvement in shape fixability or the like of a press formed product can be achieved.