Several common troubleshooting problems and solutions for CNC machine tool faucet making machines

During the use of CNC machine tools, various problems and failures will inevitably occur. The article analyzes the causes of some common faults and proposes solutions, which can easily solve problems in actual processing.
At present, CNC machining has many advantages such as stable production quality, high productivity, and improved labor conditions. CNC machine tools are widely used in the mechanical processing industry. However, during the use of the operator, one or another failure will inevitably occur. Based on some problems that students encountered during teaching activities, the author summarizes the following failure situations, analyzes them one by one, and explains their solutions.
1. The program format is illegal
After the CNC machining program compiled by some students is input into the CNC system, the program is run and graphic simulation is performed. During this process, the machine tool alarms. We can find the corresponding content of the alarm information on the alarm status list page: the program format is illegal. When this happens, we need to carefully check each program segment to find statements that do not conform to the command format of the CNC system. For example: the arc interpolation G02/03 format lacks the parameters R or I, J used to command the center position of the circle. , K; after arc interpolation, it becomes linear interpolation, but the G01 instruction is forgotten in the program. Since the G02/03 instruction is a modal instruction, the latter statement defaults to arc, so an error occurs.
2. Incorrect G code
The reason for this phenomenon is that a G code that is not supported by the system is entered into the program. When we operate a specific machine tool, we must first read the instructions that come with the machine tool, understand and master the instruction codes used by the system, and cannot make empiricist mistakes. In addition, different CNC systems, or even different models and versions of the same CNC system, support different instructions.
3. The macro program format is illegal
At present, with the continuous improvement of usage requirements and manufacturing accuracy, various non-circular curves will also be required to be processed, and most of the current CNC systems cannot support it. In order to process workpiece surface curves that meet the requirements, we must Macro programs are used to solve the problem, and there are some differences between macro programs and commonly used interpolation instructions: trigonometric functions, arithmetic operations, logical operations, etc. are used. During this process, some errors are prone to occur, such as: no pairs appears; GOTO is lost as G0T0. When this kind of problem occurs, we need to carefully check for errors and omissions in the program.
4. An "emergency stop alarm" occurs during the machine tool's return to zero process.
After the CNC machine tool is turned on, the zero return operation is performed. As a result, an emergency stop alarm is generated during this process. The reasons for this phenomenon are: the limit stop has been displaced; the travel switch has a poor working environment: there are tiny iron filings adhering to it and the cutting fluid is corroding it, causing the contact to move inflexibly and cannot move after being pressed. Bounce back to original shape. The solution is to fix the limit stop or clean or replace the travel switch.
5. During processing, the local dimensional error of the workpiece is too large
This phenomenon mainly occurs when the machine tool has been used for a long time. Due to the relative movement between the screw and the nut during use, friction and wear will inevitably occur, and the entire screw is not evenly worn. Some parts are used more frequently, resulting in inconsistent wear conditions and inconsistent gaps. There are two solutions: first, carefully measure the size of the backlash and adjust and modify it in the machine tool parameters; second, repair the screw nut pair or replace it with a new one.
6. When processing the same workpiece, the size of the first piece is normal, but the second piece has a large error.
Some people think that this phenomenon is caused by the different selection of cutting parameters during processing, or by wear and tear during the use of the tool. In fact, one issue is ignored: tool tip arc radius compensation. Since the tool tip arc of turning tools is generally relatively small (such as R0.4, R0.8, etc.), and the tool tip arc radius does not affect the size when we normally process the outer circle and end face, people tend to ignore it. If there is machining of special surfaces such as arcs, tool nose arc radius compensation is used, but it is not canceled after using it. Since this command is a modal command, it will have an impact on some subsequent processes. The way to solve this problem is to develop good habits in programming. Use the tool tip arc radius compensation instructions in pairs. As long as this instruction is enabled, it must be canceled after the machining process is completed.
7. The stroke limit position of the tool is inappropriate, and individual parts of the workpiece cannot be processed.
When processing the inner hole of the workpiece or turning (including cutting off) close to the chuck, you will sometimes encounter this prompt: overtravel in the X or Z direction. For this situation, the design defects of the machine tool itself can usually be eliminated. The most likely reasons are: the installation position of the hardware limit switch is incorrect or the software limit parameter settings are unreasonable. Solution: First, add a tool holder auxiliary device to the tool holder appropriately to allow the tool to hang out a certain distance, while ensuring stiffness to avoid affecting cutting; second, this is also our most scientific method: appropriately adjust the hardware limits. position of the bit switch or modify the data size in the software limit parameter (parameter number 1320, 1321 in FANUC).