Optical Tool Length Measurement for Small-Diameter Beam Occlusion
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Solution Overview
Problem
Non-contact tool setting apparatuses face measurement inaccuracies when measuring tools with diameters less than the beam width, as they only partially occlude the light beam, leading to errors in tool length determination and requiring complex, expensive optical designs to maintain focus.
Innovation Solution
A method for tool length measurement using a non-contact tool setting apparatus that involves moving the tool through the light beam, generating a trigger signal when the beam intensity crosses a threshold, and applying a tool length correction to account for the nominal tool diameter being less than the beam width, allowing for accurate measurements with wider, less tightly focused light beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the beam width is reduced to ensure tools can substantially occlude the beam, then measurement accuracy is improved, but device complexity and cost increase due to complicated optical designs
Solution Approach 1:
The patent changes the parameter of beam width from narrow to wide, and introduces a correction factor based on tool diameter to beam width ratio. This allows using simpler, wider beams while maintaining measurement accuracy through mathematical correction rather than relying on tight optical focusing.
Solution Approach 2:
The patent replaces the mechanical/optical approach of tight beam focusing with a computational approach using correction factors. Instead of using complex optical elements to narrow the beam, the system uses a wider beam and applies mathematical corrections to compensate for the partial occlusion effect.
2Measurement precision
If the beam is tightly focussed to improve measurement accuracy, then measurement precision is improved, but reliability deteriorates due to sensitivity to contamination and misalignment
Solution Approach 1:
The patent changes the beam width parameter from narrow (tightly focused) to wide (gently focused or collimated), which inherently improves reliability by reducing sensitivity to contamination and misalignment while maintaining measurement accuracy through the introduction of diameter-based correction factors.
3Ease of operation
If a fixed trigger threshold is used for beam occlusion detection, then ease of operation is improved, but measurement precision deteriorates for tools with diameter less than beam width
Solution Approach 1:
The patent introduces dynamic adjustment of the trigger threshold based on the measured tool diameter. The trigger threshold is no longer fixed but varies according to the ratio of tool diameter to beam width, allowing accurate measurements across different tool sizes while maintaining ease of operation through automated adaptation.
Solution Approach 2:
The patent changes the trigger threshold from a fixed parameter to a dynamic parameter that depends on tool diameter and beam width ratio. This allows the system to adapt to different tool sizes and maintain measurement precision without requiring manual recalibration or complex optical adjustments.
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
This approach enables accurate tool length measurements for tools with diameters less than the beam width, reducing the need for complex optics and improving measurement reliability, while allowing the use of collimated or gently focused light beams, which are easier to maintain and less prone to contamination.
Implementation Method 1
a transmitter for emitting a light beam having a beam width and a receiver for receiving the light beam
Implementation Method 2
the tool being moved by the machine tool into or out of the light beam in a direction along the length of the tool... causing a change in the beam intensity signal
Data Source
Figure 1
Figure 2~3c
Figure 4
AI summary
A method for tool measurement using a non-contact tool setting apparatus mounted to a machine tool. The non-contact tool setting apparatus comprises a transmitter (10) for emitting a light beam (12;80) having a beam width and a receiver(14)for receiving the light beam(12). The receiver (14) generates a beam intensity signal describing the intensity of received light. The method is for measuring a tool (84) having a nominal tool diameter less than the beam width such that fully inserting the tool(84)feature into the light beam (80) would only partially occlude the light beam(80). The method comprises moving the tool through the light beam (12;80) thereby causing a change in the beam intensity signal and generating a trigger signal when the beam intensity signal crosses a trigger threshold. A size of the tool(84) is derived using the trigger signal generated. The method also comprises a step of applying a tool length correction (e.g. a change to the trigger threshold, trigger delay etc) that accounts for the nominal tool diameter of the tool (84)being less than the beam width.