In the CNC machine tool assembly, adjustment and maintenance competition, the installation and commissioning of Renishaw 's Primo™ measuring system became a major highlight.
The same question?
During pre-competition technical training and post-competition debriefing sessions, many participants raised the same question:
Why, after installing the Primo™ probe on the Neway machine tool equipped with a FANUC system used in this competition, did the machine tool probe perform a step of "rotating" to measure four points on the inner circle of the ring gauge during the calibration program of the Renishaw Goprobe macro program software?
To answer this question, you need to understand two key points:
01. The purpose of the "rotation" action during the execution of the machine tool probe calibration program;
02. Hardware structure of the machine tool spindle that affects this action;
So what is the purpose of the "rotation" motion?
Three words—find the center
The complete set of actions of the latest version of the calibration macro program currently used by Renishaw actually includes:
Step 1: The machine tool probe measures the inner circle of the ring gauge by either "rotating and measuring once" or "measuring once at 0°/180° spindle orientation respectively". Through macro program calculation, the center of the ring gauge is automatically found, and the measuring ball is moved to the accurate center of the inner circle of the ring gauge;
Step 2: The calibration macro program is used to measure again the eccentricity of the inner circle probe ball relative to the main axis center in the X and Y directions, as well as the effective radius of the probe ball in the X and Y directions.
So, what are the hardware components of the machine tool spindle that affect this action?
spindle encoder
Because the function of the spindle encoder is to provide feedback on the spindle's rotational position and speed, it is not a standard feature on most machine tools on the market. Without it, the 180° spindle orientation cannot be completed.
Taking FANUC system programming as an example, the M19 spindle orientation to 0° is a standard function, but when the M19S180 command is executed, only machine tools with encoders on the spindle can achieve the spindle orientation to 180°. Otherwise, the spindle cannot achieve any specified angle orientation except 0°.
Therefore, machine tools equipped with spindle encoders:
The calibration macro program can be generated and run by selecting the option to "measure once at 0°/180° spindle orientation". Detailed instructions:
The spindle is oriented to 0° to measure four points on the inner circle of the ring gauge. The spindle is then oriented to 180° to measure four points on the inner circle of the ring gauge again. The center position is calculated automatically by adding the two center positions and dividing by two, using a macro program. This completes the first step of finding the center.
Machine tools without a spindle encoder:
The calibration macro program should be generated and run using the "rotate and measure once" method. Detailed instructions:
The spindle rotates at a speed of less than 1000 rad/min, touching four points on the inner circle of the measuring ring gauge like an edge finder. Based on the positions of these four points, the center position of the ring gauge is automatically calculated directly by a macro program.
The saying "all roads lead to Rome" perfectly illustrates this point, which is a great example of Renishaw's innovative technology: by adjusting the macro program software according to different hardware conditions, a solution can be found.
