Key points of high-speed cutting operation in vertical machining center

With the continuous development of processing operations, some highly complex curved parts and multi-process processing parts have become commonplace, and its fine processing requirements are originally higher. The requirements for its final processing accuracy and surface quality are often at 0.01mm or even higher. The traditional processing of multi-process workpieces on ordinary processing equipment needs to be carried out on several or even a dozen different processing machines, and multiple clamping and waiting for processing will consume a lot of non-processing time, so the processing efficiency is difficult to improve. In order to break this processing limitation, the vertical machining center has been applied in batches because the machining machine tool is not only controlled by the CNC numerical control system, but also equipped with a tool library and automatic tool changing device, through the control of these advanced functional components, you can achieve a high degree of automation and composite centralized processing capabilities. Therefore, it is the main production equipment for high-precision and efficient processing of highly complex workpieces and multi-process processing workpieces. The following is a small series of Xianji network to introduce several important aspects (machine tools, tools, processing technology) that affect the high-speed cutting of vertical machining centers.

Highly complex surfaces and multi-process workpieces are highly efficient fine machining, which is the most important machining feature of vertical machining center. In addition to being equipped with a tool library and automatic tool changing device, the machine tool can automatically replace the workpiece processing tools, but also has the characteristics of high-speed processing. The spindle speed is generally 8000 revolutions per minute, and some models even reach tens of thousands of revolutions, and the fast speed of the feed system is more than 24 meters per minute. These excellent machine attributes lay the foundation for high-speed cutting of workpieces. However, high-speed cutting is different from ordinary cutting, and there are many factors affecting the final processing accuracy and surface quality of the workpiece. In summary, there are mainly several important aspects of machine tool factors, tool factors, process system factors, processing technology factors and workpiece itself factors, focusing on a few more typical factors.

Processing technology: The vertical machining center completes its processing task by executing the machining program of the workpiece. The quality of NC machining program directly affects the final machining accuracy and efficiency of the workpiece in high-speed cutting. The key of machining program is the choice of workpiece processing. The cutting technology mainly includes the process route suitable for high-speed cutting, the cutting method, the cutting route, the optimized high-speed processing parameters and the way of sufficient cooling and lubrication.

In principle, the tool path of high-speed cutting mainly adopts stratified ring cutting, generally uses the oblique track feed mode, and the direct vertical downward feed is easy to appear the phenomenon of falling edge, so it is not suitable. The milling force of the oblique path feed method is gradually increased, so the impact on the tool and the vertical machining center spindle is smaller than that of the vertical cutting tool, which can significantly reduce the phenomenon of the falling edge of the cutting tool.

Machine tool: The high-speed cutting of the workpiece refers to the high-efficiency processing completed under the premise of ensuring the machining accuracy of the workpiece. Of course, the machine tool has high-speed cutting performance is a necessary condition to achieve high-speed cutting of the workpiece, and the vertical machining center has the characteristics of such high-speed processing. In general, the need to pay attention to the realization of this processing form of machine tools are:

Spindle and feed system with high speed: the most core component of vertical machining center is the spindle and feed system, the rotation accuracy and rotation speed of the spindle system is the key to ensure high-speed cutting of the workpiece, which requires the configuration of the spindle system to compact structure, light weight, strong rigidity, minimal inertia and the corresponding characteristics of good several key indicators. The feed system is also the same as the requirements of the spindle in ensuring high-speed feed at the same time, but also to ensure that the positioning accuracy of the machine tool and repeated positioning accuracy to meet the parameters set by the machine tool.

More flexible lubrication and cooling methods: high-speed operation of the machine tool spindle is bound to produce a lot of high temperature, in order not to cause high temperature deformation of the spindle system, lubrication and cooling is a very important part, in general, for long-term operation in the high speed state of vertical machining center spindle is generally equipped with oil cooler for cooling. In terms of lubrication, closed oil immersion is generally used, and these two means can ensure the accuracy of the machine tool spindle when running at high speed.

Tool: The tool is a part that directly acts on the workpiece, and its merits are directly related to the normal high-speed cutting of the vertical machining center. In addition to the choice of geometric parameters to be reasonable, the material of the tool is a key factor. The tool material suitable for high-speed cutting of the workpiece should meet two requirements, one is that the tool used should have a high wear resistance, only in this way can ensure that the tool in high-speed cutting, not easy to form serrations and thickness changes of intermittent chip, effectively prevent the dynamic balance of the tool damage, resulting in accelerated tool wear. To have a high hardness and toughness, at the same time meet these two in order to withstand the impact and vibration caused by high-speed rotation of the tool, without collapsing and breaking.