Machine Tool Rotary Table Misalignment Detection by Tilted Rotation
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Solution Overview
Problem
Existing methods for detecting misalignment of machined workpieces on rotary tables are inaccurate due to low detection accuracy when the workpiece has a certain level of balance, especially with motors of high output or lightweight workpieces, making it difficult to detect misalignment states effectively.
Innovation Solution
A misalignment detection method and device that involve rotating the rotary table with a mounted object in a tilted state to measure both centrifugal and gravitational forces, calculating the difference between reference and actual current values to accurately detect misalignment, regardless of motor output or workpiece weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the traditional imbalance detection method is used to detect misalignment of machined workpieces on rotary tables, then the method can detect imbalance of rotating body materials, but the detection accuracy is low when the workpiece has a certain level of balance
Solution Approach 1:
The invention changes the operational parameters of the rotary table by rotating it to specific tilted angles (first angle for centrifugal force measurement, second angle for gravitational force measurement) instead of rotating only at horizontal positions. This parameter change enables the detection system to measure both centrifugal and gravitational force components, thereby improving misalignment detection accuracy for balanced workpieces that were previously undetectable using traditional horizontal-only rotation methods
2Power
If a motor with large output is used to rotate the rotary table, then the motor can handle heavier workpieces, but the fluctuation component of the current value caused by misalignment becomes relatively small making misalignment detection difficult
Solution Approach 1:
The invention changes the rotational state parameters by introducing tilted angle rotation in addition to horizontal rotation. By measuring current values at specific tilted angles where gravitational force components are maximized, the system enhances the detectable signal for misalignment even when using high-power motors that produce smaller relative fluctuations during horizontal operation
3Speed
If the weight of the target workpiece is light compared to the weight of the rotary table, then the rotary table can rotate smoothly, but the fluctuation component of the current value caused by misalignment becomes small making misalignment detection difficult
Solution Approach 1:
The invention changes the rotational angle parameters to include tilted positions where gravitational force acts on the misaligned workpiece. By rotating the rotary table to a second tilted angle and measuring the current value, the system amplifies the effect of even small misalignments on lightweight workpieces, making the fluctuation component detectable despite the overall light load
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
Enhances misalignment detection accuracy for machined workpieces by accounting for both centrifugal and gravitational forces, allowing for precise detection of misalignment states even with balanced objects.
Implementation Method 1
When the rotary table is rotated, a centrifugal force acts on the placed object according to the rotational phase
Implementation Method 2
a gravitational force component acting on the placed object varies according to the rotational phase
Data Source
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AI summary
A misalignment detection device (75) includes a reference current storage unit (76) configured to store, as a reference current value, a drive current supplied to a drive motor (46a) when a rotary table is rotated at a predetermined rotation speed about a first axis in a reference state in which a mounting surface is in a horizontal state and a mount target is not mounted, and a misalignment detection unit (77). The misalignment detection unit (77) tilts the rotary table with the mount target attached to the mounting surface so that the mounting surface is at a predetermined angle relative to the horizontal surface, and acquires, as an actual current value, a drive current supplied to the drive motor (46a) when the rotary table in the tilted state is rotated at the predetermined rotation speed about the first axis. The misalignment detection unit (77) calculates the difference between the acquired actual current value and the reference current value stored in the reference current storage unit (76), and detects a misalignment state based on the obtained difference value.