Coordinate Measuring Machine (CMM) is a precision measuring tool mainly used to detect the size, shape, position and other characteristics of objects. It obtains the coordinate data of the workpiece through probe contact or laser scanning, thereby achieving the measurement of the geometric shape of the workpiece. Common measurement methods include:
1. Contact measurement
Contact measurement is the most common measurement method, usually using a probe with a stylus to perform contact measurement on the workpiece. The basic process is as follows:
Measurement principle: By contacting the surface of the workpiece with a stylus, the measuring machine records the movement trajectory of the stylus and obtains the corresponding coordinate points.
Measurement steps:
Select the probe and install it onto the coordinate measuring machine.
Select appropriate measurement paths and points based on the shape and accuracy requirements of the measurement target.
Automatically move the probe to each measurement point and obtain coordinate data through program control of the measuring machine.
The measuring machine calculates based on these coordinate data and ultimately outputs parameters such as the size and shape of the workpiece.
Contact measurement has high accuracy and is commonly used to measure components with complex or small shapes.
2. Non contact measurement
Non contact measurement uses laser, optical, or imaging probes to obtain coordinate data of the workpiece. Common non-contact measurement methods include:
Laser scanning: using a laser beam to scan the surface of an object, and calculating the surface contour of the object through the reflected laser beam. This method is suitable for workpieces with complex surfaces or transparent materials.
Optical measurement: Capturing surface images of workpieces through cameras or optical sensors, analyzing image data to obtain geometric information of workpieces. The advantage of this method is that it has a fast measurement speed, but its accuracy is slightly lower compared to contact based methods.
Non contact measurement is usually used for workpieces with larger surfaces or simpler shapes, and will not cause any damage to the workpiece.
3. Triggered and Scanning Measurements
Triggered measurement: The probe emits a signal when it comes into contact with the surface of the workpiece, recording the coordinates of that point. This is the most common contact measurement method, suitable for workpieces with relatively simple dimensions and shapes.
Scanning measurement: The probe moves along the surface of the workpiece while in contact with it, and records the coordinate points in real time. This method is used to measure workpieces with complex shapes or requiring high precision.
4. Control of measurement process
Automated measurement: Most modern coordinate measuring machines can perform automated measurement. During the measurement process, the probe's movement path and measurement points are controlled by a computer to automatically obtain data and generate measurement reports.
Manual measurement: Some coordinate measuring machines also support manual operation, and operators need to manually adjust the position of the measuring machine to complete the measurement task. Manual measurement is commonly used for small batches or measurement tasks with specific requirements.
5. Data processing and analysis
After the measurement is completed, the system will provide coordinate data, which can be further processed and analyzed as needed, including:
Tolerance analysis: Check whether the dimensions of the workpiece meet the design requirements.
Geometric tolerance analysis: Check whether the geometric shape of the workpiece meets the specified standards.
Statistical analysis: Collecting measurement data from multiple workpieces for quality control.
These data can be generated into reports through software tools, providing detailed measurement results and analysis.
summary
The measurement methods of three-dimensional coordinate measuring machines include two main methods: contact and non-contact. Depending on the characteristics of different workpieces and measurement requirements, the appropriate measurement method should be selected. Through automation control and high-precision measurement technology, CMM can provide efficient and accurate workpiece measurement services, widely used in manufacturing, quality control and other fields.