Circumferential milling is a kind of milling technology that makes cylindrical surfaces by the circumferential feeding motion of the milling cutter. In recent years, due to the progress of machining centers and tool manufacturing technology, this kind of milling technology has been promoted and widely used.
At present, this circular milling principle has been widely used in milling holes, milling inner (outer) grooves, milling thread, chamfering, milling ring end face, milling counterbore, and other different processing tasks.
This kind of circumferential milling technology has the advantages of high efficiency, and a wide application range, and can be combined with other processing technology, which makes it more and more widely used in industrial production, especially in the automobile industry.
To achieve the circular week to the movement of the cutter is the precondition of peripheral milling conditions, on the CNC machining center, as well as by X axis and Y axis of the circular arc interpolation to realize the cutter circular week for sports, but can be by X axis and Y axis and Z axis helical interpolation to realize the milling spiral feed movement, and through the CNC program to achieve a variety of peripheral milling process. At present, the high dynamic machining center driven by a linear motor and equipped with a precise NUMERICAL control system can not only reduce the basic time of circumferential milling but also improve the machining accuracy of circumferential milling. Thus, circumferential milling can replace boring and tapping with drilling and milling thread.
There are two ways and two tools for milling holes using circumferential milling technology. One is used in the cylindrical cutter body grinding spiral blade of the circumference of the milling tool or in cylindrical cutter body tangential arrangement of several indexable blades of the circumference of the milling tool, this kind of tool 1 for shallow hole processing, milling hole, spindle milling cutter around the Z axis for circular feed movement. The other is equipped with a round blade or diamond or rectangular blade multi-function end milling cutter, this kind of tool can be used for machining not more than five times the diameter of the tool of the deep hole, milling hole, end milling cutter for spiral feed movement, machining center of the X axis, Y axis and Z axis linkage (that is, 3 axis spiral interpolation movement).
When milling holes using the first method, the cylindricity of machining holes mainly depends on the geometric accuracy of milling cutter manufacturing. For the shape precision of machining hole, no matter which tool is used for milling hole mainly depends on the interpolation precision of NUMERICAL control system. The surface roughness of machined holes is related to the precision of the tool and the selected cutting parameters.
With the use of circumferential milling technology, both rough machining can also be realized, for impassable hole can also be milling out flat bottom hole, step hole or conical hole, and can also be in the bottom of the hole at the bottom of the circumferential surface of the circumferential milling processing.
The hole is always using multi-edge milling cutter to achieve, which is usually compared with the boring process of single edge boring cutter, milling hole can use a larger back tool quantity, so milling hole has very high processing efficiency, and even in intermittent milling intersecting holes will not produce milling cutter jitter.
At present, in a high-speed machining center driven by a linear motor, the circular milling process is applied to machining the SUNTHAI bearing seat holes of the automotive engine gearbox at a feed rate of 40m/min, and the hole’s roundness can reach 6m. Because of this good machining accuracy, this can eliminate the subsequent finishing process.
The principle of circumferential milling can be used to milling screw holes and drilling and milling thread. The process of drilling and milling thread can not only simplify the production process but also greatly shorten the processing time.
When using the principle of circumferential milling to process thread holes, the thread can be milled on the thread bottom hole which is pre-machined or drilling and milling on the solid material which has no pre-machined thread bottom hole.
The application of circular milling technology and its composite cutter can not only shorten the basic time and auxiliary time but also optimize the machining and improve the machining accuracy of the workpiece.
To make better use of circumferential milling technology, the selection of machine tools and the design and manufacture of cutting tools should be emphasized when planning the production process of the workpiece. High dynamic machining center or high-dynamic milling center should be selected for machining tasks requiring high precision of the workpiece. Due to the use of a direct drive and fast CNC control system, the machine has high dynamic response performance. And the traditional machining center due to the use of indirect transmission (such as screw and other mechanisms), will produce transmission gap and error, in the interpolation movement due to mechanical transmission system lag will cause tracking error. The fast CNC control system adopted by the high dynamic machine ensures extremely fast response speed and can make full use of the dynamic characteristics of the feed shaft to make it move accurately, thus greatly improving the multi-axis interpolation accuracy and machining accuracy. Improving the precision of the cutting tool is another necessary condition to improve the precision of circular milling. For example, some tool manufacturers, in order to improve the precision of diamond circumferential milling tools, use CNC 5-axis were machine tool, to ensure that the shape of the tool accurate (up to 3m). In addition, in order to improve the cutting conditions of the circumferential milling cutter, the cutter manufacturer adopts a tangential arrangement of the indexable blade on the cylinder of the milling cutter to form a positive forward Angle, thus reducing the radial cutting force and improving the shape accuracy of the machining hole.
It can be seen that with the dynamic performance of machine tools and interpolation accuracy (nano interpolation), the tool technology and its manufacturing accuracy improved, as well as the strengthening of cooperation between users and tool manufacturers, in the future, the circular milling process will be better promoted and applied.