The application and development of mechanical probes The mechanical probes are generally 6mm steel balls. The spring is used to tighten the measuring rod. When the workpiece is touched, it can be retracted, and the circuit can be turned on to send an optical signal. The coordinate position of the measured surface can be obtained by the indication of the photoelectric probe and the machine coordinate position. Need to record the coordinate value of each measurement, and then manually calculate, and finally manually enter the calculated value into G54 ~ G57, especially when the workpiece origin in the center, the calculation is complex, low efficiency, easy input in the input process, Parts are often scrapped due to incorrect input of coordinate values. In order to avoid this kind of error, the tool setting process is optimized, some subroutines are developed, and the numerical calculation and the coordinate value input are changed to be automatically executed by the numerical control system. In this process, the R parameter is used to calculate the coordinate value, and the @ instruction is used to automatically input the coordinate value to G54 to G57. When measuring the origin of the workpiece, simply input the corresponding offset value, and then call the corresponding subroutine to complete the input of the workpiece origin. The workpiece origin measurement is simple and quick, the most important is to improve the efficiency and accuracy of the workpiece origin measurement, and is not prone to human error. Take the MSGP6101 floor boring and milling machine as an example to illustrate the development process.
The MSGP6101 floor boring and milling machine system is SIEMENS 840C. The spindle can be converted vertically and horizontally. During the tool setting process, the X, Y and Z offsets differ depending on the standing mode. Therefore, the variable R50 is introduced in the subroutine to determine its offset. In the measurement, only the corresponding offset value is assigned to R50 during measurement, and the system automatically calculates the actual position value of the workpiece coordinate system. To measure the corresponding subroutine for each axis (in order to perform a program in the program, do not conflict with other subroutines, the subroutine is represented by three digits, in which the second digit represents the axis to be measured, and 1 and 4 are The X axis, 2, 5 is the Y axis, 3, 6 is the Z axis; the third digit represents the measured value will be automatically transferred into the set of registers in G54-G57).
The application of improved X-axis tool setting process probe in part borrowing. Some aerospace cabin parts have complex space structure. There are grouped hole systems on the aerospace. The blanks are generally fine castings, and the machining allowance is small. Some errors in the size of castings are relatively large. Before processing, it is necessary to ensure that the machining allowance of each hole system is uniform by borrowing bias, otherwise, the hole systems will not be able to be fully ejected. The parts on the 4-32 +0.0 250mm rudder shaft hole machining accuracy and high requirements, the rudder shaft hole diameter before machining is Φ30, such as improper adjustment will cause the four rudder shaft hole can not be all pulled out, and the rudder shaft hole is The parts that require the highest machining accuracy are found on the part, so correcting the rudder shaft hole with four angles of 90° each becomes the key to machining.
The original method of correcting is to install the dial indicator on the spindle of the machine tool and then use four rudder shaft holes to borrow parts. The specific process is: first adjust the dial indicator installed on the spindle of the machine tool to make it measure the Φ32 standard hole. When the display is zero; then use the centimeter dial four rudder shaft hole blank hole, adjust the C axis, so that the table reading is within (+0.8, -0.8) mm, both to ensure that the boring allowance is greater than 0.2mm. If the reading of the plate to a hole table is greater than the above range, the C-axis needs to be adjusted, and then the other three holes must be re-find again. Until the four holes are in the table, the reading of the table is within (+0.8, -0.8) mm. The angular position of the hole is determined and the borrowing ends. At this time, the coordinate of the C axis is the origin of the C axis of the workpiece coordinate system. . Because the size error and angular position error of the casting blank hole casting are relatively large, each workpiece often needs to use the dial repeatedly, which is time-consuming.
Concluding remarks The probe is an important accessory of the CNC machine tool. The use of a good probe is very beneficial to the actual production. It not only can reduce the labor intensity of the workers, but also can effectively guarantee the accuracy of the parts and improve the production efficiency. How to use and develop the function of the probe to maximize its efficient, accurate, and convenient function in the actual production is also an important aspect of the efficiency enhancement of CNC machine tools.
