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Improving the timeliness, reliability, and efficiency of CAM programs is a top priority in improving machining efficiency. Engineers need to optimize the entire process, optimize toolpaths, and perform collision checking to ensure machining quality and efficiency.
The processes involved in mold manufacturing can be broadly divided into several major links: mold flow analysis, mold design, numerical control processing, and fitter assembly test. Among them, the quality of the mold and the delivery cycle are two elements of competition in the industry. The biggest bottleneck in the industry generally lies in the numerical control processing link, and the length of time for the numerical control processing, the reasonableness of the processing technology, the rational distribution of machining and electrical machining, etc., will also affect the quality and cycle of the future fitter assembly test mode. All companies are working hard to ensure that the manufacturing process is controlled, the process is optimized, and the efficiency is continuously improved. Of course, all of these requirements for CNC machining ultimately boil down to CAM programming.
Guarantee the controllability of processing
All CNC machine tools are run through CAM program instructions, and the CNC machine itself is running 24h, this time can not be changed, therefore, to increase the efficiency of the CAM program has become a primary issue.
Improving the timeliness, reliability, and efficiency of CAM programs is a top priority in improving machining efficiency. Timeliness refers to the ability of the programming engineer to assemble the CAM toolpath and generate the machining program in time according to the node's design data. Reliability means that the processing program generated by the CAM can ensure the safety in the entire machining process and completely eliminate the collision tool. The occurrence of over-cutting and other phenomena; the efficiency of the program means that the process route is reasonably arranged, the number of clamping operations is reduced, and the machining strategy is reasonably applied. The appropriate tool and corresponding cutting parameters are selected according to different machine tools to reduce the jitter during the operation of the tool. , empty process, improve processing efficiency.
After the machining program is generated, the machine tool operator uses the program list provided by the CAM engineer (see Fig. 1) to the tool storehouse to borrow the tool holder and the tool, and executes the machining according to the cutting parameters specified in the CAM program, and records the processing completion data. Production managers supervise the actual completion of each shift and each procedure according to the processing time provided by the schedule. The core of these steps is the CAM engineer's grasp of different materials, tools, tool holders, machine tool cutting performance, and detailed cutting parameters. If the cutting parameters are inaccurate, everything is out of control. Of course, CAM engineers also need to ensure the accuracy of the tool holder and tool holder length on the program. This requires that the NC machining program is generated automatically by the software and the fixture length is calculated by the software after the collision analysis. At present, in some mold processing industries in the industry, machining parameters are determined by machining operators themselves, handwritten program orders, no tool holders or machine tool collision analysis, and the length of fixtures may be caused by visual inspection, which may cause the process to lose control or reduce processing efficiency. The program automatically generated by the CAM can completely avoid the human error caused by the manual handwriting process, so as not to use the wrong tool holder and the length of the wrong tool.
Figure 1 Sample program
CAM programming process optimization
The optimization of the CAM programming process refers to the optimization of the entire route arrangement of the workpiece processing sequence.
For non-regular mold parts, such as large bumper molds and other large oblique roof blocks, it is usually necessary to reverse several angles to complete the processing. The mounting method and process reference of each processing step are all affecting the final parts. The critical factors of the machining accuracy, therefore, the accuracy of such components often become the key to the length of the entire mold production cycle. In a well-known mold factory in Japan, the processing precision of such parts and moving mold can be guaranteed within 0.03mm, and the fitter can really reach the high level of unmatched equipment. These all reflect the perfect CAM programming process, of course, this process is ultimately to rely on the information on the CAM program single cover to pass to the machine, the workpiece clamping and machining standards established.
Make CAM programs more efficient
Nowadays, numerical control technology is gradually developing in the direction of unmanned and automated. The influence factors of operators are becoming less and less. Therefore, the accuracy and efficiency of numerical control processing can only be guaranteed if the program itself is optimized and smooth. This first requires the CAM engineers to optimize the toolpaths that are generated and also to inspect the various collisions.
1. Rough tool path optimization
In the roughing process, optimization measures for smoothing the tool path to a maximum degree can generally be taken on the premise of ensuring the accuracy of the part machining. In Fig. 2, it can be seen that the feed rate is closer to the actual value given by the CAM by observing the change of the actual F value during the cutting process of the machine tool. The NC program generated by the ordinary tool path has many deviations. The tool path is decelerated and accelerated frequently, which results in low processing efficiency. If the programming time given by the program list is 10 hours, it may take 13 hours for actual processing. If the machine tool G00 is fast enough, it can also take a smoother tool path as shown in Figure 3 to improve machining efficiency.
Fig. 2 Comparison of toolpaths generated before and after the "race line" option of high-speed machining in PowerMILL software is opened
Fig. 3 If the machine's G00 speed is fast enough, this machining-efficient machining strategy can be used
2. Optimization of finishing tool path
Optimizations in finishing are usually rounded corners of the tool path to avoid sharp corners (see Figure 4).
Figure 4 Tool Path Rounding Optimization
3. Collision interference check of tool holder and machine tool
Collision interference check between the holder and the spindle head of the machine tool is an essential step for all NC programs. In this step, the first step is to ensure the safety in NC machining, that is, to ensure that there is no collision interference; the second is to select the shortest tool to process as many areas as possible, because no matter how the optimized tool path is processed, if there is no principle, Increasing the length of the tool and shank for machining will inevitably greatly reduce the actual machining efficiency.
Collision interference check is divided into two parts: one is the interference check between the tool holder and the machined part (see Figure 5); the other is the interference check between the machine part (spindle head) and the machined part.
Figure 5 Tool holder collision check
For the structure where the spindle head portion of the machine tool is a rotary body and is concentric with the spindle, the head of the machine tool can be simplified into a tool shank portion for interference checking (see Fig. 6). If the machine head and spindle are not concentric and have a structure of long and short axis portions, Sometimes, in order to ensure full processing with short and short tool shanks, the tool holder collision check is performed first, and then the machine motion simulation is performed (see Figure 7).
Figure 6 Interference Check of Tool Holder and Machined Part
Fig. 7 Interference checking of the spindle of the machine tool and the machining part
Conclusion
CAM programming is not merely a representation of a programming strategy or a programming method, but a combination of integrated knowledge such as programming methods, machining processes, tooling, tool holders, and the use of cutting materials. In practical work, technical engineers must combine these knowledge with each other and use them flexibly to achieve good processing results, thereby improving mold processing quality, shortening the manufacturing cycle of molds, and providing more powerful support for the development of enterprises.