Robot Arm Force Sensor Tool Holder Runout Detection
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Solution Overview
Problem
Existing machining systems face challenges in determining the attached state of tools or tool holders without adding equipment to the main spindle, particularly in detecting runout and shifts orthogonal to the spindle axis.
Innovation Solution
A machining system incorporating a robot arm with a force sensor or displacement sensor at its distal end, controlled by a unit that positions the sensor at specific measurement points to detect changes in force or displacement, allowing determination of the attached state of tools or tool holders based on detection values over time, even when the main spindle is rotating or stationary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are attached to the tool holder to detect runout, then measurement capability is improved, but device complexity increases
Solution Approach 1:
A force sensor is introduced as an intermediary device between the robot arm and the workpiece. The force sensor detects forces during workpiece handling and feeds this information to the control unit, which then determines the attached state of the tool or tool holder. This intermediary approach enables runout detection without directly modifying the tool holder with strain gauges.
Solution Approach 2:
The patent replaces the traditional mechanical strain gauge system attached to the tool holder with an electronic force sensing system. The force sensor mounted on the robot arm uses electronic measurement and control processing to detect runout, substituting the mechanical measurement approach with an electronic one that reduces overall system complexity.
2Measurement precision
If equipment is added to the main spindle to detect attached state, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The robot arm with force sensor serves as an intermediary measurement device that indirectly detects the attached state of the tool or tool holder. Instead of adding sensors directly to the main spindle, the system uses the robot's force sensor to measure forces during workpiece handling, which reflect the attached state.
Solution Approach 2:
The robot arm performs dual functions: it handles workpieces and simultaneously serves as a measurement platform for detecting tool attachment state. The force sensor on the robot arm utilizes the natural forces generated during workpiece handling to determine attached state, making the robot serve its own measurement needs without requiring separate dedicated measurement equipment on the spindle.
3Measurement precision
If multiple measurement positions are used to detect runout, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The system uses the forces naturally generated during normal workpiece handling operations to detect runout. Instead of performing separate dedicated measurement actions at multiple positions, the system utilizes the excessive forces already present during workpiece handling to simultaneously obtain measurement information, reducing additional measurement time.
Solution Approach 2:
The force sensor continuously monitors forces during the entire workpiece handling process. The control unit processes detection values obtained continuously during workpiece handling to determine the attached state, maintaining continuous useful action rather than interrupting for separate measurement operations.
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
Enables accurate determination of the attached state without additional equipment on the main spindle, reflecting runout or shifts in detection values, thus ensuring proper tool alignment and operation.
Implementation Method 1
a contact section that is attached to a distal end portion of the robot arm via a force sensor; and a control unit, wherein the control unit is configured to conduct: a measurement process of controlling the robot arm such that the contact section is positioned at a predetermined measurement position where the contact section comes into contact with a side surface of the tool or a side surface of a tool holder for attaching the tool to the main spindle, and obtaining detection values of the force sensor
Implementation Method 2
a displacement sensor that is attached to a distal end portion of the robot arm; and a control unit, wherein the control unit is configured to conduct: a measurement process of controlling the robot arm such that the displacement sensor is positioned at a predetermined measurement position where the displacement sensor can detect displacement of a side surface of the tool or a side surface of a tool holder for attaching the tool to the main spindle
Data Source
AI summary
A machining system includes a robot arm for changing a workpiece or inspecting a machined workpiece, and a probe that is attached to a distal end portion of the robot arm via a force sensor, where the robot arm is controlled such that the probe is arranged at a predetermined measurement position in contact with a side surface of a tool holder, where detection values of the force sensor are obtained over a predetermined period of time in a state where a main spindle is performing rotation operation, where an attached state of the tool holder is determined based on the detection values obtained over the predetermined period of time.