I. Flatness Inspection: Assessing the overall flatness of the working surface
The first thing to check after repair is the flatness of the working surface, which is fundamental to ensuring stable workpiece clamping.
1. Use a 00-grade bridge plate with an electronic alignment level or laser flatness meter to perform a full-field scan, covering the longitudinal, transverse, and diagonal paths.
2. Measure at 1000mm intervals. Use software to fit the data and generate a flatness error cloud map to determine if there are any local depressions or warping.
3. Acceptance criteria: Generally, the flatness error should be ≤0.1mm/m; for precision-grade platforms, it should be ≤0.05mm/m.
4. If any out-of-tolerance areas are found, the workbench must be returned to the scraping or fine grinding process for local correction.
II. Hole Spacing and Positioning Accuracy Inspection: Ensuring Consistency in Repeated Clamping
Rust often occurs at the edges of positioning holes; the geometric accuracy of the hole system must be verified after repair.
1. Use a high-precision mandrel (H7 grade) and dial indicator to measure the center distance deviation between adjacent holes, paying particular attention to holes that have undergone rust repair.
2. Select multiple reference hole groups on the platform and use the "reference extension method" to compare point by point, ensuring that the hole distance tolerance is controlled within ±0.05mm.
3. For robotic welding applications, it is recommended to use a coordinate measuring machine to model all hole positions and output a deviation report between the actual coordinates and theoretical values.
4. Avoid using worn locating pins as inspection tools to prevent misjudgment.
III. Perpendicularity and Parallelism Inspection: Ensuring Accurate 3D Spatial Positioning
If the repair involves the side or supporting structure, the spatial relationship between each working surface also needs to be inspected.
1. Use a 90° precision square with feeler gauges or a laser tracker to measure the perpendicularity of the end face to the table surface, requiring an error ≤0.05mm/100mm.
2. For multi-faceted 3D platforms, check the parallelism of opposing surfaces to ensure no misalignment during modular expansion.
IV. Surface Roughness Inspection: Preventing Impact on Contact Stability
Grinding or polishing repairs may alter surface finish; it's necessary to confirm whether it meets original design requirements.
1. Use a portable surface roughness meter to randomly measure points in the repair area. The Ra value should generally be controlled within ≤3.2μm, and for ultra-precision platforms, ≤1.6μm.
2. Excessive smoothness (Ra<0.8μm) may reduce friction, while excessive roughness affects contact point density, both detrimental to stable clamping.
V. Dynamic Verification: Simulating Actual Usage Conditions
In addition to static testing, it is recommended to conduct clamping trial runs for verification:
1. Install a typical workpiece and complete a full welding process, observing whether the robot path is smooth and whether there are any collisions or offset alarms.
2. After disassembly, re-clamp the same workpiece and check the repeatability of the weld position; the deviation should be ≤0.1mm.
This step effectively identifies hidden problems such as "data is qualified but not applicable in practice."
VI. Establish Testing Records for Traceable Management
A written report should be generated after each accuracy test, including:
Testing time, ambient temperature and humidity (recommended at 20±5℃)
Instrument model and calibration status
Measurement data and pass/fail criteria
Comparative analysis before and after repair
