fig.2 experiment data<\/figcaption><\/figure>\nFrom the experimental results, we can see that:<\/p>\n
( 1) Overcut always occurs on the up\u00a0milling side\u00a0of work piece.\u00a0On the contrary, the missing cut\u00a0phenomenon\u00a0always appears\u00a0on the down\u00a0milling side, and the maximum point of overcut and missing cut is at the end milling cutter extension farthest.\u00a0This point accords with the deformation pattern\u00a0of the tool and the tool extension length during up\u00a0milling and down\u00a0milling.<\/p>\n
( 2) As the spiral angle of the end milling cutter is less than 30 \u00b0, the perpendicularity error value will increase with the increase of the helical angle, whether on the forward milling side or on the reverse milling side.<\/p>\n
When the helical\u00a0angle\u00a0is greater than 40 \u00b0, it will decrease with the increase of the helical\u00a0angle. Therefore, it can be considered that when the end milling cutter has a smaller\u00a0helical\u00a0angle\u00a0or a larger\u00a0helical\u00a0angle, the shape accuracy of its groove milling is high, Although it seems a contradiction.<\/p>\n
( 3) From the perspective of machining accuracy, when the helical\u00a0angle\u00a0is 0, the cutting edge is straight and the accuracy is the highest. However, from the basic characteristics of the helical\u00a0angle\u00a0of the end mill, the end mill will completely present intermittent cutting in this case. This kind of machining with large cutting impact requires high manufacturing accuracy of the tool itself.<\/p>\n
<\/p>\n
A experiment of side milling with helical angle and 4-edge end milling cutter<\/h1>\n
The side of the workpiece is milled on a vertical machining center with a 4-edge end milling cutter with a helical angle\u00a0of 30 \u00b0 and 55 \u00b0. We compare the influence of the change of the two end milling cutters with the cutting width (radial feed) on the machining accuracy. When the diameter of the end milling cutter is 25mm, the 45 # steel with the hardness of 94HRB shall be cut by the straight milling method and dry cutting. The cutting parameters are feed rate of 100 mm\/min, cutting speed of 26 mm\/min and cutting depth of 38 mm The measured perpendicularity error, flatness error and surface roughness after machining are shown in Figure 3.<\/p>\n