Geometric definition, rapid prototyping, and cutting force analysis of cylindrical milling tools with arbitrary helix angle variations

Abstract

In this work, a method is developed for geometric definition and analysis of cylindrical milling tools having various free-form variations of helix angle. The method is based on replicating a position vector on each cutting edge to generate a point set for the whole tool envelope using piece-wise rotation and magnification matrices which are varied according to mathematical laws describing the intended variable shape of the tool. The computed point sets are applied in additive manufacturing of samples of such tools having non-conventional shape features by transforming the point sets to stereolithography formats that are sliced to guide the 3D-printing processes. This manufacturing route that simplifies the realization of arbitrary helix profiles on milling tools is a major contribution of this work since such tools are gaining popularity for their passive damping of vibrations and reduction of cutting forces but are notoriously difficult to manufacture, limiting their exploitation. Analyses are shown about the effects of the considered variable profiles on milling cutting force. These suggest that cutting forces can be greatly suppressed by the proposed free-form helix angle variations. For example, relative to a conventional fixed helix tool of same mean helix angle, the innovative tools recorded 40.33%–84.42% and 60.53%–67.81% force reductions at axial depths of cut of 1 and 5 mm. This demonstrates that innovative variable tool profiles which can be realized through the simplified rapid prototyping technique are promising for advanced sustainable manufacturing of parts with preferred surface conditions.

3D FEM Simulation of Titanium Alloy (Ti6Al4V) Machining with Harmonic Endmill Tools

“…For this study, the helix angle, also called cutting edge inclination angle, is chosen as the control parameter. The choice of this parameter is based on its significant influence in defining the helix shape of the cutting edge of a tool, [8,12], as it helps to smoothen and extend the duration and geometric length of contact between a cutting edge and a workpiece, hence reducing impacts if appropriately selected [14]. Two endmill tools with different helix-shape profiles will be considered here: a standard tool and a harmonic tool, as shown in Figs.…”

“…The standard tool has a constant helix angle of 25 0 while the harmonic tool has a range of variable helix angles, having a mean value of 25 0 . Equation 1, see [14], that describes the harmonic tool is…”

“…However, there have been very little studies on the effect of the variable helix angle of an endmill tool on a milling process, with [13] comparing the experimental and numerical performance of cutting force on wave form tools. Then, [14] analyzed the cutting forces acting on end milling tools which have variable free-form helix angle profiles. This existing knowledge gap gives rise to the need to carry out a study on the effects that a variable helix-shaped endmill tool geometry would have on milling Ti6Al4V.…”

A study of interferential tool position correcting algorithms in 3D impeller variable-axis rough plunge milling

“…In plunge milling, the tool is mainly subjected to axial force, while its rigidity in the axial direction is far better than that in the radial direction. In addition, Ozoegwu and Eberhard 9 developed a method for defining and analysing the geometry of cylindrical milling tools with various free-form helix angle variations, by which the axial force that occurred during plunge milling could be reduced on a large scale. However, a problem persists whereby the cutting force in plunge milling is still large and unstable if the process parameters are not correctly selected.…”

Profile design and simulation verification of hard whirling tool for ZC1 worm machining

“…To achieve high-precision and high-efficiency machining of face gear, Mo et al 18 proposed the cutting technology and tool design for face gear skiving. Ozoegwu and Eberhard 19 developed a method for geometric definition and analysis of cylindrical milling tools having various free-form variations of helix angle, simplifying the manufacture of milling cutters to achieve arbitrary helical profiles.…”