Cut-Off Tool Breakage Detection With Dual-Timing Lathe Sensing
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Solution Overview
Problem
Conventional lathes with non-mechanical-type cut-off tool breakage detection methods are ineffective during continuous machining, particularly when the back spindle does not hold the bar material, leading to inaccurate detection and elongated machining times.
Innovation Solution
A lathe equipped with a contact-type breakage detector that includes a retractable sensor to detect the cut-off tool breakage by hitting the uncut end of the bar material, allowing for accurate detection at two distinct timings: immediately after cutting and at the start of continuous machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a non-mechanical-type breakage detecting means is used, then the machining time is short, but the detection accuracy is insufficient when the back spindle does not hold the bar material
Solution Approach 1:
The detection process is segmented into two distinct timings: first detection timing when the back spindle holds the bar material (using non-mechanical-type means), and second detection timing when the back spindle does not hold the bar material (using mechanical-type means with sensor). This segmentation allows each detection method to be used in its most effective operating condition, resolving the contradiction between speed and accuracy.
Solution Approach 2:
The system dynamically switches between non-mechanical-type and mechanical-type detection methods based on the operational state of the back spindle. When the back spindle holds the bar material, non-mechanical detection is used for speed; when it doesn't hold the material, mechanical detection with sensor advancement is used for accuracy. This dynamic adaptation resolves the contradiction.
2Measurement precision
If a mechanical-type breakage detecting means with a sensor is used, then the detection accuracy is improved, but the machining time is elongated due to sensor advancement time
Solution Approach 1:
The detection process is segmented into two distinct timings: first detection timing when the back spindle holds the bar material (using non-mechanical-type means), and second detection timing when the back spindle does not hold the bar material (using mechanical-type means with sensor). This segmentation allows each detection method to be used in its most effective operating condition, resolving the contradiction between speed and accuracy.
Solution Approach 2:
The mechanical sensor advancement action is performed only partially or selectively - specifically only when the back spindle does not hold the bar material and breakage detection is critically needed. This partial application of the mechanical detection method avoids the full time penalty of sensor advancement in all cases, while still providing accurate detection when necessary.
3Reliability
If the sensor advances to hit the uncut end, then breakage detection is possible when back spindle does not hold material, but the detection timing becomes complex
Solution Approach 1:
The detection process is segmented into two distinct timings: first detection timing when the back spindle holds the bar material (using non-mechanical-type means), and second detection timing when the back spindle does not hold the bar material (using mechanical-type means with sensor). This segmentation allows each detection method to be used in its most effective operating condition, resolving the contradiction between speed and accuracy.
Solution Approach 2:
The system uses feedback from the back spindle's holding state to determine which detection method to employ. The controller monitors whether the back spindle holds the bar material and automatically selects the appropriate detection timing and method, simplifying the overall control logic despite having two detection modes.
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 solution enhances the accuracy of cut-off tool breakage detection without prolonging machining time, ensuring reliable operation even when the back spindle does not hold the bar material.
Implementation Method 1
a contact-type breakage detector provided with a sensor retractably advancing to an advancing position where the sensor could hit the end of the bar material if it remains after the cut-off tool cuts off the bar material
Data Source
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AI summary
A lathe includes a spindle (11), an opposite spindle (16), a tool post (30), a controller (70), and a contact-type breakage detector (40). The controller (70) determines whether the cut-off tool (TO3) is broken according to a control parameter for controlling at least one of the spindle (11) and the opposite spindle (16) at a first detection timing (ST3) immediately after the cut-off tool (TO3) cuts off the bar material (B1) while the opposite spindle (16) holds the bar material (B1) held by the spindle (11). The controller (70) determines whether the cut-off tool (TO3) is broken according to a detection result by the contact-type breakage detector (40) at a second detection timing (ST6) different from the first detection timing (ST3).