Processing Machine Feedback Control for Straightness Error Cancellation
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Solution Overview
Problem
Existing processing machines face challenges in achieving ultra-precision processing due to non-reproducible or short-duration straightness variance, which conventional methods cannot effectively address, leading to significant processing errors.
Innovation Solution
A processing machine equipped with dual moving parts, sensors, and a control system that continuously measures and adjusts the relative positions of the moving parts to compensate for straightness variance, using feedback control to minimize processing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional processing machines with guides are used, then the structure is simple and easy to manufacture, but the straightness variance causes processing errors in the order of tens of nanometers or more
Solution Approach 1:
The patent implements a feedback control system where sensors detect the actual positions of moving parts during operation, and the control device uses this information to compute correction amounts that compensate for straightness variance. This closed-loop feedback mechanism enables ultra-precise processing by continuously correcting deviations from the ideal movement path.
Solution Approach 2:
The patent replaces reliance on purely mechanical guides with a hybrid system that uses sensors and computational control. Instead of depending solely on mechanical guide accuracy, the system substitutes mechanical precision requirements with electronic detection and software-based correction, achieving higher precision without proportionally increasing mechanical complexity.
2Manufacturing precision
If straightness variance is measured in advance as in PTLs 1 and 2, then the measurement is simple, but it cannot address non-reproducible or short-duration straightness variance
Solution Approach 1:
The patent transitions from static pre-measurement to dynamic real-time measurement. Sensors continuously detect straightness variance during actual operation, capturing non-reproducible and short-duration variations that occur during processing. This dynamic approach ensures corrections are based on actual conditions rather than predetermined values.
Solution Approach 2:
The control device computes correction amounts in advance for each control cycle based on detected straightness variance, preparing correction data before actual processing occurs. This preliminary computation of corrections ensures that compensation is ready and applied immediately, addressing time-critical variations.
3Manufacturing precision
If a fine movement stage is added as in PTL 3 to reduce straightness variance, then processing precision improves, but the machine becomes larger and more complicated
Solution Approach 1:
The patent makes existing sensors serve multiple functions: they detect both the primary position parameters needed for normal control and the straightness variance parameters needed for precision correction. This multi-functionality eliminates the need for separate dedicated measurement devices, achieving high precision without adding structural complexity.
Solution Approach 2:
The control device acts as an intermediary that processes sensor data and computes correction amounts, mediating between the detected straightness variance and the actual positioning control. This computational intermediary replaces the need for complex mechanical correction mechanisms, achieving precision through software rather than hardware complexity.
Data Source
AI summary
In a processing machine 1, an X-axis control unit 33X, in each control cycle Tc, controls the position of an X-axis table 9X in the X-direction by feedback. The Z-axis control unit 33Z, in each control cycle Tc, acquires an up-close detection value of the position of the Z-axis table 9Z in the Z-direction, computes a second deviation based on a difference between the acquired detection value and a target position, and controls a Z-axis drive source 23z so that the second deviation is reduced. The Z-axis control unit 33Z, in each control cycle Tc, acquires an up-close detection value of a first error comprised of a deviation of the X-axis table 9 in the Z-direction, and increases or reduces the second deviation based on the detection value of the first error so that at least a portion of an error in a relative position of a workpiece 103 and a tool 101 in the Z-direction originating from the first error is cancelled by movement of the Z-axis table 9Z in the Z-direction.