Toroidal Cutter Research Articles

Collision-free Tool Motion Planning for 5-Axis CNC Machining with Toroidal Cutters

Collision detection is a crucial part of CNC machining, however, many state-of-the-art algorithms test collisions as a post-process, after the path-planning stage, or use conservative approaches that result in low machining accuracy in the neighborhood of the cutter’s contact paths. We propose a fast collision detection test that does not require a costly construction of the configuration space nor high-resolution sampling of the cutter’s axis and uses the information of the neighboring points to efficiently prune away points of the axis that cannot cause collisions. The proposed collision detection test is incorporated directly as a part of the tool motion-planning stage, enabling design of highly-accurate motions of a toroidal cutting tool along free-form geometries. We validate our algorithm on a variety of benchmark surfaces, showing that our results provide high-quality approximations with provably non-colliding motions.

Point Pair-Based Expression of Cutter Swept Envelopes in Five-Axis Milling

This paper proposes an efficient method of formulating cutter swept envelopes in five-axis milling based on conformal geometric algebra. The surface of the rotary cutter is represented as a canal surface, as the envelope of a one-parameter family of spheres. The swept envelopes generated by the general rigid motion of the cutter can be regarded as the envelopes of a two-parameter family of spheres. With the help of the dual representations of spheres and planes in conformal space, a point pair-based expression of the swept envelopes is formulated analytically, which represents two surfaces uniformly. By using the present method, the swept surfaces of a conical cutter, a drum-shaped cutter, and a toroidal cutter are illustrated. As an application, two types of collision detection methods for 5-axis milling are presented based on the point pair-based envelope expression. The benchmark examples demonstrate that the use of the proposed envelope expression significantly improves computational efficiency.

Modelling of the Face-Milling Process by Toroidal Cutter

When face milling using a toroidal cutter, with a change in the depth of the cut, the entering angle varies as well. An experimental test of the influence of cutting parameters, such as the depth of the cut and the feed per tooth on the cutting force components and surface roughness parameters, was conducted. The experimental test was carried out using a DMU 100 monoBLOCK CNC machine with registration of cutting force components and surface roughness parameters Ra, Rz, and RSm. FEM analysis of the face-milling process was also carried out and compared with the experimental results. The average deviation of the FEM values for cutting force components does not exceed 12%. Experimental models were established for each force component. It was shown that the depth of the cut has the strongest influence on each force component. The feed per tooth has a little impact on the cutting force. The obtained model of the feed force component is the most complex, and the model of the Fa component is only linear. The influence of the ap parameter on the surface roughness parameters is nonlinear and nonmonotonic. In the range of approx. ap = 2 mm, there is a maximum surface roughness.

A new approach to find gouge free tool positions for a toroidal cutter for Bézier surfaces in five-axis machining

We implement and test a multi-point machining tool positioning technique that positions the tool using only a variation on gouge checking. The result is a method that is roughly twice as fast as an earlier method that performed a numerical search to find a tool position with multiple points of contact with the design surface. A GPU implementation provides an additional factor of ten speedup. Verification of the method was done via simulation and machining and measuring physical parts.

Geometry and tool motion planning for curvature adapted CNC machining

CNC machining is the leading subtractive manufacturing technology. Although it is in use since decades, it is far from fully solved and still a rich source for challenging problems in geometric computing. We demonstrate this at hand of 5-axis machining of freeform surfaces, where the degrees of freedom in selecting and moving the cutting tool allow one to adapt the tool motion optimally to the surface to be produced. We aim at a high-quality surface finish, thereby reducing the need for hard-to-control post-machining processes such as grinding and polishing. Our work is based on a careful geometric analysis of curvature-adapted machining via so-called second order line contact between tool and target surface. On the geometric side, this leads to a new continuous transition between "dual" classical results in surface theory concerning osculating circles of surface curves and osculating cones of tangentially circumscribed developable surfaces. Practically, it serves as an effective basis for tool motion planning. Unlike previous approaches to curvature-adapted machining, we solve locally optimal tool positioning and motion planning within a single optimization framework and achieve curvature adaptation even for convex surfaces. This is possible with a toroidal cutter that contains a negatively curved cutting area. The effectiveness of our approach is verified at hand of digital models, simulations and machined parts, including a comparison to results generated with commercial software.

A new method for choosing between ball-end cutter and toroidal cutter when machining free-form surfaces

End-milling of free-form surfaces on multi-axis CNC machines are complex and expensive operations involved in the production of many high-value parts, molds and stamping dies. For such operations, the choice of the cutter type to use is very important given the considerable impact of this choice on the quality of the machined surface and the duration of the operation. In this paper, a new method for choosing between ball-end cutter and toroidal cutter is provided. This procedure gives a good hint on the best tool to employ with no need to carry out any machining simulation.

The influence of inclination of the axis of the toroidal tool on a flat surface roughness

The paper follows the experimental analysis of the influence of the tool axis inclination on the roughness on a flat surface. The tool used in this case is a toroidal cutter radius around the corner. This will process a flat surface in 4 cases. We will experiment with the processing of a flat surface with the tool axis inclined in the positive direction A, negative direction A, positive direction B and negative direction B. The term of comparison in the four cases is surface quality. The purpose paper is to determine the best option for inclination tool toroidal.

Hibridna analitičko-diskretna metodologija za izračunavanje putanje rezne ivice kod helikoidnog toroidnog reznog alata pri petoosnom glodanju

This paper presents a new method to calculate path scallop height of toroidal cutter during free-form surface machining in five-axis milling. The scallop height was defined as the distance between the tool intersection point and the normal point on the part surface. The tool intersection point was determined analytically by implementing the grazing method to define the swept curve of toroidal cutter. Meanwhile the normal surface on the part surface was determined using a hybrid analytical and discrete based methodology. The part surface was discretized by a number of normal vectors, then, they were used for defining the part surface mathematically. In this study, the effect of helical angle of cutting edge was taken into consideration in the model development. The proposed model was successfully used to generate the path scallop data for two model parts with free-form surface profiles. The effect of helical angle to the scallop height was also tested and the results showed that the helical angle tends to decrease the scallop height. The verification test to check the accuracy of the proposed method was performed and the results proved that the method was accurate.

Cutting layer and cutting forces in a 5-axis milling of sculptured surfaces using the toroidal cutter

The purpose of this article was to evaluate the significance of the influence of five- axis orientation parameters of a toroidal cutter axis and the geometrical parameters of the machined sculptured surface on the intersection of the cut layer in a 5-axis machining. An impact assessment was performed by simulating concave-convex and convex-concave surfaces using a discrete method of direct transformation in a CAD environment. It was shown that only the radius of curvature of the surface in the feed direction and the angle of the tool axis affected the change in the intersection of the cutting layer. Subsequently, experimental tests were conducted that aimed at determining the mathematical models of the influence of these important parameters on the components of the cutting force. The object of the experimental studies was a convex and concave surface of a turbine blade of Inconel 718 alloy. The R300-016B20L-08L Sandvik Coromant toroid cutter was used for the tests. Based on the results of the study it was found that the lead angle in the machining of the convex surface and concave turbine blade should be continuously varied with the change of radius of curvature in the direction of the machined surface profile

Wpływ parametrów kinematycznych i geometrycznych na przekrój warstwy skrawanej w pięcioosiowej obróbce powierzchni złożonych

Results of simulation studies made using the direct CAD method are presented. The significance of the influence of the toroidal cutter axis orientation parameters and curvature radius of the sculptured surface on the cut layer in a 5-axis milling of the convex-concave and concave-convex surfaces, was assessed.

Five-axis milling of sculptured surfaces of the turbine blade

PurposeThe purpose of this paper is to determine the influence of a toroidal cutter axis orientation and a variable radius of curvature of the machined contour of sculptured surface on the five-axes milling process. Simulation and experimental research performed in this work are aimed to determine the relationship between the parameters of five-axes milling process and the shape and dimensional accuracy of curved outline of Inconel 718 alloy workpiece.Design/methodology/approachA subject of research are sculptured surfaces of the turbine blade. Simulation research was performed using the method of direct mapping tools in the CAD environment. The machining research was carried out with the use of multi-axis machining center DMU 100 monoBLOCK DMG, equipped with rotating dynamometer to measure the components of the cutting force. To control the shape and dimensional accuracy, the coordinate measuring machine ZEISS ACCURA II was used.FindingsIn this paper, the effect of the toroidal cutter axis orientation and the variable radius of curvature of the machined contour on the parameters of five-axes milling process and the accuracy of the sculptured surfaces was determined.Practical implicationsFive-axes milling with the use of a toroidal cutter is found in the aviation industry, where sculptured surfaces of the turbine blades are machined. The results of the research allow more precise planning of five-axes milling and increase of the turbine blades accuracy.Originality/valueThis paper significantly complements the current state of knowledge in the field of five-axes milling of turbine blades in terms of their accuracy.

Prediction of cutting forces and vibration in titanium alloy milling using a toroidal cutter

Titanium alloys are frequently used when a high strength-to-weight ratio and good hot hardness, corrosion resistance, and fatigue properties are needed. One of the most widely used of these alloys is Ti-6Al-4V. However, titanium alloys with these characteristics generally have poor machinability and tend to cause the machine-tool-workpiece-fixture system to vibrate. In this work, a model for predicting the cutting forces in milling is adapted for milling with toroidal cutters, and the dynamic effects of machining are included in the model. The cutting constants are determined in milling experiments, and the dynamic parameters used in the vibration model are determined in modal tests. By including cutting vibration in the model, the vibration behavior during milling can be understood and the cutting forces in real milling processes can be better simulated.

Metoda sterowania kątem prowadzenia osi frezu w pięcioosiowej obróbce łopatki turbiny

Presented is the own concept control method an lead angle axis of the toroidal cutter, depending on the radius of curvature of the machined sculptured surface profile. The method verified on the example machining of the turbine blade. In order to compare the effects of this method, to the classical method (without adaptation lead angle), tests were performed for both these methods.

Implementation of analytical boundary simulation method for cutting force prediction model in five-axis milling

ABSTRACTA simulation system was developed that deals with cut geometry and machining forces when a toroidal cutter is used during semifinishing in five-axis milling. The cut geometry was calculated using an analytical method called analytical boundary simulation (ABS). ABS was implemented to calculate the cut geometry when the machining used an inclination angle and a screw angle. The effect of tool orientation on the cut geometry was analyzed. The accuracy of the proposed method was verified by comparing the cut lengths calculated using ABS with cuts obtained experimentally. The result indicated that the method was accurate. ABS was subsequently applied to support a cutting force prediction model. A validation test showed that there was a good agreement with the cutting force generated experimentally.

Analytical Boundary Method for Obtaining Feed Scallop of Toroidal Cutter in Multi-Axis Milling

This paper presents a new method to calculate the feed scallop height for a toroidal cutter during a free-form surface machining in multi-axis milling. The proposed method is an extended analytical boundary method to define the cut geometry during a free-form surface milling. The algorithm was developed by taken into account the existence of inclination angle. The proposed method was successfully implemented to calculate the scallop for two model parts with different surface profiles. The accuracy was verified by comparing the scallop height calculated using the proposed method with those measured using Siemens-NX. The results proved that the proposed method was accurate

Dokładność geometryczna obróbki powierzchni łopatki turbiny frezem toroidalnym

Dokładność geometryczna obróbki powierzchni łopatki turbiny frezem toroidalnym

Geometria warstwy skrawanej w obróbce powierzchni złożonych frezem toroidalnym

Geometria warstwy skrawanej w obróbce powierzchni złożonych frezem toroidalnym

Balancing of the transversal cutting force for pocket milling cutters: application for roughing a magnesium-rare earth alloy

Removing material efficiently in end milling usually involves taking a width of cut equal to the cutter diameter, i.e., to mill in full slotting as much as possible. However, in this case, end mills are very sensitive to the effects of cutting forces. Cutter deflection and vibrations may become limiting factors, especially at high machining rates and with long overhangs. To overcome these constraints, a new machining method to end mill workpieces can be considered. It is called “balancing of the transversal cutting force” (BotTCF). Indeed, this new machining method allows us to reduce deflection and vibrations and can therefore increase productivity. All the existing studies have used toroidal cutters with round inserts. Hence, the present study will focus on the application of the BotTCF to pocket milling cutters, considering their much more complex geometry. The goal is to determine the optimal inclination of the cutter axis, so as to minimize the transversal cutting force. In order to find this optimal inclination, a new cutting force model has been developed tailored to the pocket milling cutters. Then the BotTCF methodology has been applied to this type of cutter. An experimental validation has been carried out, and results validate the overall approach.

Intelligent Optimization for Sculptured Surface CNC Tool-paths

This paper suggests the application of genetic algorithms for the intelligent generation of optimum sculptured surface CNC machining tool-paths. Two robust full quadratic mathematical models are developed relating the physical relation among machining surface deviation and resulting cutting time; quality objectives which are treated as conflicting ones. The independent variables are the tool inclination angles -lead and tilt- in the case of 5-axis machining and step-over engagement among subsequent XY passes; using a toroidal cutter. A Box-Behnken response surface design was established to prepare and conduct simulation experiments in a cutting-edge manufacturing software using a benchmark multivariable sculptured surface and a special multi-axis tool-path strategy. The genetic algorithm utilizes both models expressed as a common Pareto-based fitness function so that multi-objective optimization is achieved, yet; arriving at one optimum solution to ease the efforts of end-users and numerical control programmers. The methodology is validated by utilizing the genetic algorithm's recommendations for the settings of the machining parameters and the optimum tool-path simulation is performed to verify the operation.

Wpływ orientacji osi freza toroidalnego na składowe siły skrawania w pięcioosiowej obróbce łopatki turbiny ze stopu INCONEL 718

Wpływ orientacji osi freza toroidalnego na składowe siły skrawania w pięcioosiowej obróbce łopatki turbiny ze stopu INCONEL 718