Tool-Shaft Deflection Sensing for Accurate Workpiece Contact Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining the position of a workpiece in machine tools are time-consuming and prone to measurement errors, especially with cast parts that have slag residue, leading to inaccurate material removal during machining.
Innovation Solution
A device and method using a measuring arrangement with a non-rotatable measuring graduation and position sensors on a shaft, connected to a computer that evaluates position values to determine contact between the tool and workpiece, allowing for precise position determination and contact detection through displacement signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a probe is used to determine workpiece position, then the position can be measured, but the process becomes time-consuming due to tool swapping and the measurements are inaccurate when slag residue is present
Solution Approach 1:
The invention combines the workpiece probing function and tool positioning function into a single tool that serves both purposes. The tool with the deflectable shaft can both measure workpiece position and perform machining operations, eliminating the need to swap between probes and machining tools.
Solution Approach 2:
The deflectable shaft acts as an intermediary element that transfers force from the tool to the workpiece while providing measurable deflection. This allows the tool itself to serve as the sensing element, eliminating the need for separate probing tools.
2Measurement precision
If a probe is used to detect workpiece surface, then position data can be obtained, but measurement errors occur when slag residue is present on cast parts
Solution Approach 1:
The tool with deflectable shaft performs preliminary material removal to penetrate through slag residue layers before accurate contact with the metal surface is detected. The progressive deflection measurement allows the system to distinguish between slag contact and actual metal surface contact.
Solution Approach 2:
The invention replaces the electrical contact-based probe sensing system with a mechanical deflection-based sensing system. The deflectable shaft provides direct mechanical contact and force transmission, allowing the tool itself to sense surface contact through measurable deflection rather than electrical switching signals.
3Productivity
If the tool is moved towards the workpiece without contact detection, then machining can proceed, but material removal accuracy is reduced leading to increased machining time
Solution Approach 1:
The system continuously monitors the deflection of the tool shaft during machining operations and provides real-time feedback to the control system. This allows dynamic adjustment of machining parameters and detection of actual material contact, ensuring precise material removal while maintaining high productivity.
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 enables efficient and accurate determination of workpiece position, reducing processing time and material removal errors by distinguishing actual surface contact from slag residue, thus improving machining precision and efficiency.
Implementation Method 1
a measuring arrangement with a measuring graduation arranged on the shaft in a rotationally fixed manner and at least one position sensor which is arranged fixedly with respect to the shaft, wherein the at least one position sensor is designed to scan the measuring graduation and to generate position values therefrom which indicate a position of the shaft
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a device and a method for detecting contact between a tool (4) and a workpiece (6) in a machine tool, wherein the tool (4) and the workpiece (6) are movable relative to each other and the tool (4) or the workpiece (6) is connected to a shaft (2) in a rotationally fixed manner.The device comprises a measuring arrangement (60, 160) with a measuring scale (61, 161) arranged non-rotatably on the shaft (2) and at least one position sensor (64, 65, 66, 67, 68, 69) which is arranged in a fixed position relative to the shaft (2), and a computer (40, 140, 240, 340, 440, 540), wherein: • the at least one position sensor (64, 65, 66, 67, 68, 69) is configured to scan the measuring scale (61, 161) and generate position values (P1, P2, P3, P4, P5, P6) from it which indicate a position of the shaft (2), • the position values (P1, P2, P3, P4, P5, P6) are transmitted to the computer (40, 140, 240, 340, 440, 540) are supplied, which includes means that, by evaluating a progression of position values (P1, P2, P3, P4, P5, P6), determine the contact between tool (4) and workpiece (6) and signal the result of the evaluation via the status of a displacement signal (VS).