Constant probe orientation for fast contact-based inspection of 3D free-form surfaces using (3+2)-axis inspection machines

A new probe optimization method for contact based (3+2)-axis inspection machines is proposed. Given an inspection path of a stylus on a free-form surface, an optimal orientation of the stylus is computed such that (i) the inclination angle of the stylus is within a given angular range with respect to the surface normal, (ii) the motion of the stylus is globally collision free, and (iii) the stylus remains constant in the coordinate system of the measuring machine. The last condition guarantees that the inspection motion requires only the involvement of the three translational axes of the measuring machine. The numerical simulations were validated through physical experiments on a testcase of a tooth of a bevel gear due to the surface complexity and probe accessibility. This optimized method was compared to 3-axis and 5-axis inspection strategies, showing that the fixed (3+2)-axis stylus returns more accurate inspection results compared to the traditional 3-axis approach and similar to 5-axis approach

Threading holder based on axial metal cylinder pins to reduce tap risk during reversion instant

Internal thread profiles are used widely in manufacturing processes with the aim of assembling/disassembling different components during maintenance activities from the aeronautics sector until common industrial parts. The threading process is one of the last operations carried out to obtain those components, and consequently, it is an operation of high added value. Threading is a complex operation that must carefully synchronize the rotation with the feed movements to avoid tool breakage during the instant of tapping reversion stage. In order to avoid this risk, several toolholders were developed present in the literature but deficiencies in terms of stability and productivity. Therefore, in this work, a new toolholder is proposed in which the common springs used to mitigate the lack of perfect synchronization between rotation and feed movements are replaced by elastic metal pins achieving a torsional compliance toolholder. The results show that the use of the proposed toolholder implies not only a productivity increase but also a surface integrity improvement as well as a stress reduction that the cutting tap is subjected and thus, achieving a substantial improvement in the current tapping processes. In particular, the use of the proposed toolholder implied a 75% reduction of the maximum stress achieved in the reversal instant, improving 20% tool life with an increase of 30% cutting speed. Therefore, the use of the proposed toolholder implies a substantial improvement in the current tapping processes

Effects of laser-textured on rake face in turning PCD tools for Ti6Al4V

The demand inherent to the aeronautical industry in terms of productivity and quality requirements leads to develop new cutting tools. Hence, PCD tools meet the requirements in productivity while machining low machinability aeronautical alloys such as Ti6Al4V. Tool chipbreakers play a considerable role in terms of tool life. However, due to the extreme conditions (temperature and pressure) required to manufacture PCD tools, any complex geometry on tool rake faces is not viable, so chipbreakers are not possible, except for those external to inserts. This work proposes a groove-type laser engraved chipbreaker design and a manufacturing methodology, with experimental validation on turning a Ti6Al4V workpiece. The so-manufactured chipbreakers achieve titanium alloy chip fragmentation, making easy chip removal from the cutting zone. A set of experiments involving various laser parameters to characterize the PCD depth and surface integrity and experimental validation for those chipbreakers designs were carried out in finishing cutting conditions. The optimum parameters for the engraving of PCD were found, obtaining satisfactory breakage of titanium chips. Chip length was always below 17.29 mm.Authors are grateful to Basque government group IT IT1337- 19, the Ministry of Mineco REF DPI2016-74845-R and PID2019- 109340RB-I00, and the UPV/EHU itself for the financial aid for the pre-doctoral grants PIF 19/96

Large Spiral Bevel Gears on Universal 5-axis Milling Machines: A Complete Process

AbstractThe cutting of bevel gears on universal 5-axis milling machines represents a promising solution to replace the conventional cutting process. The process is highly flexible and does not require neither special gear generating machines nor special tools. Thus, it is particularly suitable for small batches, prototypes or to obtain a specific and unique product. In this way, we have focused on the machining of a large-sized spiral bevel gear, from the initial design to the final machining. A gear will be machined using different milling paths and scallop heights. Each of the different strategies will be applied in consecutive teeth, and afterwards these teeth will be analyzed to check some of the gear quality parameters (roughness, profile angle variation, single pitch error...) with the final goal of finding the optimal cutting strategy. As finishing tool, an air turbine finishing tool was evaluated as an alternative technology apart from the typical tapered ball end mill

Geometric Modelling of Added Layers by Coaxial Laser Cladding

AbstractThe laser cladding process is based on the generation of a melt-pool in a substrate where a filler material is injected, generating high quality layers with a minimum heat affected zone. This process is industrially used to generate 3D parts, being a sustainable alternative to traditional machining. One of the most important aspects for its industrial application is to know the clad geometry in order to calculate the deposited layer thickness. This work presents a model in which, starting from the concentration of injected material, real energy distribution and the melt-pool geometry, clad height is estimated. All input variables are obtained by three previous validated models