The positioning precision of the CNC machine-tool refers to the position accuracy which can be obtained by the coordinates of the machine tools under the control of the CNC device. The precision of positioning of the CNC machine can be understood as the accuracy of the exercise of the machine tool.
The machines or ordinary tools are seized manually and the positioning accuracy is mainly determined by the reading error, and the movement of the CNC machine is obtained by the instructions of the digital program. The movement of each movement component of the machine tool is completed under the control of the CNC device. Precision is an important test.
1. Precision detection of the right movement
The precision of positioning of the linear movement is generally under the air load conditions of the tool-tool and the workbench. According to national standards and international standardization organizations (ISO standards), CNC machine tools must be based on laser measurement. In the absence of laser interference meters, for general users, it can also be measured with a standard rule with optical reading microscope. However, the accuracy of the measurement instruments must be 1 to 2 levels higher than the measured precision.
In order to reflect all multiple positioning errors, the ISO standard stipulates that each positioning point is a divided area disseminated composed of the average value of the data calculation and the disseminated deviation belt composed of five times.
2. Repeat the accuracy of the precision of positioning in linear motion
The instrument used for tests is the same as the detection positioning precision. The general detection method is to measure three locations with each coordinating route and the two ends. Reading number. With a half of the greatest difference in the three positions, positive and negative symbols are attached to the precision of repetitive positioning of the coordinate.
3. Back to the point of origin of the linear movement returns the accuracy of the precision
The point of origin returns the accuracy, which is essentially the accuracy of repetitive positioning of a special point on the axis of the coordinates, therefore its detection method is completely the same as the precision of repeated positioning.
4. Reverse error detection of linear movement
The reverse error in linear movement is also called a discharge volume. Errors such as reverse space and elastic deformation. The greater the error, the lower the precision of positioning and repetitive positioning.
The method of detecting inverted errors consists in moving a distance to the positive or reversed movement in advance in the calendar of the measured coordinate axis and to stop the position as the reference. Stop position and reference position. Multiple determinations (generally 7 times) are carried out in the middle of the route and the three positions at both ends.
5. The positioning precision of the rotating worker
The measurement tools include standard transfer tables, a corner polyhedron, a round light grid and parallel optical pipes (permeable instrument), etc., which can be selected according to specific conditions. The measurement method is to make the working angle a front (or inverted) angle and stop, lock it and position it. . The maximum value of the real corner and the theoretical value (instruction value) of each positioning position for a week is the punctual error error. If it is a CNC for workbench, every 30 as a target position, and quickly position the position of each target position from two directions in the direction of twice. Deviation of the position.
Given the real requirements of dry transformers, generally focusing on several right angles such as 0, 90, 180, 270, etc., and requires the accuracy of these points to increase a level of a level than other angles.
6. repeated precision test of the score of filming work
The measurement method consists in repeating the positioning of three positions 3 times in the week following the work of filming and in testing it under the rotation of the front and opposite directions. The maximum value accuracy of the theoretical value of all the reading values of the corresponding position. If it is a CNC workbench, take a measurement point every 30 as a target position, then quickly locate the positions of each target position from two directions. In the GB10931-89.
7. Back to the point of origin of the return to the return precision detection
The measurement method is to return to the point of origin of the 7 arbitrary positions to determine its stop position and to use the maximum difference between reading as an original point to return accuracy.
It should be noted that the detection of existing positioning accuracy is measured in rapid plane and positioning. In addition, the results of the positioning accuracy are linked to the working state of the environmental temperature and to the working state of the coordinate axis. The element is mainly installed on the drive engine. This is the error caused by a thermal extension, and certain tools-tools use pre-move methods (pre-regulating) to reduce the impact.
The repetitive positioning accuracy of each coordinate shaft reflects the most basic precision indicator of the axis. Currently, due to the growing function of the CNC system, the error of the sports accuracy system of each standard movement of the injector, such as the accumulation of the accumulation of height and the error reverse space, can be offset. cannot be compensated. Therefore, if the tool-tool is authorized, it is preferable to choose a machine tool with high positioning precision.
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