Workpiece Holding Detection via Polishing Load Difference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Workpieces are prone to breakage due to abnormal holding in processing apparatuses, leading to reduced yields, increased costs, and productivity losses, caused by improper insertion or buoyancy during double-side polishing and lapping processes.
Innovation Solution
A processing apparatus and method that utilize a control unit to record and compare polishing loads when the workpiece is properly held, detecting abnormal holding by calculating differences exceeding a threshold value, allowing for precise and timely detection and prevention of breakages without the need for additional costly sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a workpiece is held manually or by automatic handling apparatus, then the workpiece can be positioned in the holding hole, but abnormal holding occurs due to operation mistakes or apparatus breakdown, causing workpiece breakage
Solution Approach 1:
The patent performs preliminary detection of workpiece holding state by measuring the weight of the upper turn table before polishing begins. The control unit compares the measured weight against a predetermined threshold to determine if the workpiece is properly held in the carrier, preventing abnormal holding from causing breakage during the polishing process
Solution Approach 2:
The patent implements a feedback mechanism where the measuring instrument continuously monitors the weight of the upper turn table, and the control unit processes this information to detect abnormal holding conditions. The system provides feedback by comparing measured weight values with expected values, enabling real-time detection of improper workpiece placement or displacement
2Productivity
If polishing load is controlled by adjusting upper turn table height, then polishing rate can be controlled, but additional measuring instruments and control mechanisms are required
Solution Approach 1:
The patent makes the existing measuring instrument serve multiple functions: it is used both for detecting abnormal workpiece holding by measuring the weight of the upper turn table and for controlling the polishing load by measuring the weight during polishing. This eliminates the need for separate measuring instruments for these two functions, reducing device complexity while maintaining productivity control
3Ease of operation
If the upper turn table is moved upward to position the carrier, then the workpiece can be held, but the weight of the upper turn table is reduced to zero when fully downward, making load measurement difficult
Solution Approach 1:
The patent performs the weight measurement at a specific preliminary stage when the upper turn table is in the upward position with the carrier properly positioned, before the polishing process begins. At this stage, the weight of the upper turn table includes the weight of the carrier and workpiece, providing a reliable baseline measurement for detecting abnormal holding conditions
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 efficient detection of abnormal holding with high precision at low cost, preventing workpiece and apparatus breakages, reducing restoration costs, and improving productivity by ensuring proper holding before processing.
Implementation Method 1
An upper turn table holding section is usually provided with a measuring instrument that measures the weight of the upper turn table
Implementation Method 2
The water or slurry collected in the holding hole of the carrier placed on the lower turn table gives buoyancy to the workpiece and makes the workpiece easily lie out of the holding hole
Data Source
AI summary
A workpiece processing apparatus including a control unit that is provided with a storage medium on which a polishing load measured when an upper turn table is moved downward to a fixed position in a state wherein the workpiece is properly held in holding hole of the carrier is recorded in advance, calculates a difference between a polishing load measured when upper turn table is moved downward to the fixed position in a state wherein the workpiece is held in holding hole of the carrier and the polishing load recorded on the storage medium, and judges the occurrence of abnormal holding of the workpiece if the calculated difference exceeds a threshold value. As a result, it becomes possible to detect abnormal holding of a workpiece in a short time with a high degree of precision before the workpiece is processed and prevent breakages of the workpiece and the processing apparatus.