scholarly journals Analysis of advanced transpedicular screw machining technologies

2021 ◽  
Vol 24 (6) ◽  
pp. 1190-1198
Author(s):  
A. V. Savilov ◽  
A. S. Pyatykh ◽  
S. A. Timofeev

Abstract: The purpose is to improve the machining efficiency of titanium alloy transpedicular screws on highperformance machine-tools based on the selection of advanced technological approaches, and to analyze the current manufacturing technology of implants on CNC machines of the semi-automatic longitudinal turning lathe type. The efficiency is assessed using the following criteria: process performance determined by the machine time and the quality of implant processing (surface roughness, geometric accuracy, mechanical properties). It is found that semi -automatic longitudinal lathes equipped with a collet feed system and drive heads for thread whirling allow processing the implants of the transpedicular screw type in a single set-up with maximum efficiency. It is shown that the machining technology of transpedicular screws is largely determined by the features of their design. The type and shape of the thread have the greatest influence on the used cutting tool and cutting modes. The analysis of screw breakages revealed that the main failure reasons are design defects and poor machining quality of the threaded part. It is determined that the use of the thread whirling method makes it possible to obtain the thread in one cutting pass and, therefore, significantly increase the machining performance compared to the traditional technology without any loss of quality. Additional advantages of this method are the reduction in the number of tools used and follow-on finishing deburring operations. Based on the conducted analysis the manufacture of transpedicular titanium alloy screws is recommended to perform using advanced cutting tools, primarily thread whirling cutters ensuring 4 times increase in machining performance without any loss of the processed item quality and 2 times reduced surface roughness. In this case the temperature in the cutting zone decreases, which has a positive effect on processed product service life. The condition for the effective use of the cutters is equipping of the machine-tools involved in the technological process with special drive heads.

The Cutting process used in milling is one of the most common type of industrial machining methods. Similar to traditional milling spindles, the motor driven spindles are fitted with an integrated motor, thereby eliminating belts and gears for the transmission of power from the motor to the cutting tools. The innovative machine tools should be highly characterized systems in order to retain the necessary precision, efficiency and reliability. To satisfy their end user's reliability and availability requirements, both the spindle system (Tool/Tool-Holder/ Spindle) and motor tool system need to be configured for their usability and output results. However, the quality of a control device in industrial practice is greatly affected by the spindle cutting output and its reliability. The motor spindles are nothing but the rotating drive shafts which acts as axes for cutting force tools or in machining process for holding cutting instrument. Hence the spindles are one of the important factor in machining tool process and productivity, as these are used to produce parts as well as machines that produce components, which in turn have a significant impact on production levels and quality of products.


Author(s):  
Emel Kuram

Tool coatings can improve the machinability performance of difficult-to-cut materials such as titanium alloys. Therefore, in the current work, high-speed milling of Ti6Al4V titanium alloy was carried out to determine the performance of various coated cutting tools. Five types of coated carbide inserts – monolayer TiCN, AlTiN, TiAlN and two layers TiCN + TiN and AlTiN + TiN, which were deposited by physical vapour deposition – were employed in the experiments. Tool wear, cutting force, surface roughness and chip morphology were evaluated and compared for different coated tools. To understand the tool wear modes and mechanisms, detailed scanning electron microscope analysis combined with energy dispersive X-ray of the worn inserts were conducted. Abrasion, adhesion, chipping and mechanical crack on flank face and coating delamination, adhesion and crater wear on rake face were observed during high-speed milling of Ti6Al4V titanium alloy. In terms of tool wear, the lowest value was obtained with TiCN-coated insert. It was also found that at the beginning of the machining pass TiAlN-coated insert and at the end of machining TiCN-coated insert gave the lowest cutting force and surface roughness values. No change in chip morphology was observed with different coated inserts.


2020 ◽  
Vol 10 (4) ◽  
pp. 6062-6067
Author(s):  
A. Boudjemline ◽  
M. Boujelbene ◽  
E. Bayraktar

This paper investigates high power CO2 laser cutting of 5mm-thick Ti-6Al-4V titanium alloy sheets, aiming to evaluate the effects of various laser cutting parameters on surface roughness. Using multiple linear regression, a mathematical model based on experimental data was proposed to predict the maximum height of the surface Sz as a function of two laser cutting parameters, namely cutting speed and assist-gas pressure. The adequacy of the proposed model was validated by Analysis Of Variance (ANOVA). Experimental data were compared with the model’s data to verify the capacity of the proposed model. The results indicated that for fixed laser power, cutting speed is the predominant cutting parameter that affects the maximum height of surface roughness.


2016 ◽  
Vol 836-837 ◽  
pp. 584-591
Author(s):  
Xiao Jun Yang ◽  
Cheng Fang Ma ◽  
Yan Li ◽  
Dun Lv ◽  
Jun Zhang ◽  
...  

With the development of the high-speed and high-precision CNC machine tools, the interaction between mechanical system and servo drive torque in the feed system becomes more and more serious which affects the surface quality of the workpiece. In this paper, taking a small-sized vertical milling center as the research object, the characteristics of servo torque and mechanical system are analyzed, respectively. Then the influence of electromechanical matching on the tracking fluctuation of the feed system is discussed. Furthermore, aiming at the surface roughness of the workpiece, the influence of the interaction between servo torque and mechanical system on the surface quality of the workpiece is analyzed under different milling ways. Finally, a large number of experiments are carried out to verify the analysis above. At last, the optimization methods of machining precision based on electromechanical matching are put forward. It can be found that in the high-speed machining, the servo torque has lots of harmonics which act on the mechanical system with kinds of modals, leading to the vibration. The surface quality of the workpiece will be deteriorated rapidly when the mode of vibration is consistent with the sensitive direction of machining error. The surface quality of the workpiece can be significantly improved through optimizing the feed velocity and the processing method and realizing the electromechanical matching.


Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 850 ◽  
Author(s):  
Zhaojun Ren ◽  
Shengguan Qu ◽  
Yalong Zhang ◽  
Xiaoqiang Li ◽  
Chao Yang

In this paper, TiAlN-coated cemented carbide tools with chip groove were used to machine titanium alloy Ti-6Al-0.6Cr-0.4Fe-0.4Si-0.01B under dry conditions in order to investigate the machining performance of this cutting tool. Wear mechanisms of TiAlN-coated cemented carbide tools with chip groove were studied and compared to the uncoated cemented carbide tools (K20) with a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The effects of the cutting parameters (cutting speed, feed rate and depth of cut) on tool life and workpiece surface roughness of TiAlN-coated cemented carbide tools with chip groove were studied with a 3D super-depth-of-field instrument and a surface profile instrument, respectively. The results showed that the TiAlN-coated cemented carbide tools with chip groove were more suitable for machining TC7. The adhesive wear, diffusion wear, crater wear, and stripping occurred during machining, and the large built-up edge formed on the rake face. The optimal cutting parameters of TiAlN-coated cemented carbide tools were acquired. The surface roughness Ra decreased with the increase of the cutting speed, while it increased with the increase of the feed rate.


2012 ◽  
Vol 472-475 ◽  
pp. 1818-1822
Author(s):  
Wei Hua Wu ◽  
Yan Yan Guo ◽  
Can Zhao ◽  
Tao Xu ◽  
Jia Yang

To improve the production efficiency and product quality of titanium alloy TC4, with the minimum of cutting force F, surface roughness Ra, and surface peak valley height Pv as the optimized goal, using orthogonal rotating combination design method of three factors quadratic regression, the influence of cutting speed vc, feed per tooth fz and cutting width ae to cutting force (Fx, Fy) surface peak valley height Pv and surface roughness Ra are mainly studied, and the best cutting amount combination is chosen. Experiment results indicate that the best cutting parameters of titanium alloy are vc=28.588 m/min、fz=0.043 3 mm/z、ae=0.1 mm, the optimal values are =3.346 N、 =47.01 N、 =673.89 nm and =201.78 nm. This research is of theoretical significance for improving the processing efficiency and machining quality and reducing the production cost.


2011 ◽  
Vol 264-265 ◽  
pp. 967-972 ◽  
Author(s):  
E.M. Rubio ◽  
J.M. Sáenz de Pipaón ◽  
M. Villeta ◽  
M.A. Sebastián

The work presents a study of surface roughness of pieces of magnesium UNS M11311 obtained by dry turning. The study is focused in repair operations of this type of materials when they are used as inserts of metalic hybrid components. Therefore, the main limitations of this research are the values of the cutting conditions used; especially low in comparison with the usually values of these parameters used in the production of the magnesium. The followed methodology consists of a series of tests of dry horizontally turning carried out with tools of different coatings and under different cutting conditions. The design of experiments has been made by means of fractional factorial orthogonal designs and the analysis of the results by the ANOVA method. The principal result is one ranking for the combinations of cutting conditions and tool coatings based on the surface roughness expected given by the mathematical model. As first conclusion, it is possible to affirm that, the best surface finishes are obtained for low feeds. Cutting tools used in the machining of other types of materials (steel, stainless steel) can be used obtaining a quality of the surface finish similar to that obtained with tools for specific use of non-ferrous metals.


2014 ◽  
Vol 633-634 ◽  
pp. 743-746
Author(s):  
Tao Sun ◽  
Zhuo Chen

TC21 is a first high strength and damage-tolerant titanium alloy self-developed in China, which has independent intellectual property. As it is known to all, titanium alloy TC21 is one of the most widely used materials in aerospace. The improvement of cutting quality of titanium alloy is an urgent problem. In this paper, the orthogonal experiment were carried out to study surface roughness of turning TC21. The predictive model of surface roughness in turning TC21 was built by analysis of multivariable linear regression on the basis of experiment. Statistical test results indicated the established predictive model were in highly notable test status and had high reliability. These works provide references for machining TC21.


2015 ◽  
Vol 645-646 ◽  
pp. 52-57 ◽  
Author(s):  
Man Cang Song ◽  
Jian Lei Zhang ◽  
Chao Yu ◽  
Min Jie Wang ◽  
Chong Liu ◽  
...  

Some typical kinds of PCD and PCBN compacts are selected to be machined by WEDM, and a series of processing tests are taken. After machining, the surface roughness of cutting section, the processing quality of cobalt-rich interface layer and the edge of superhard material layer are measured by surface profiler and 3D microscope. The results show that processing quality is affected by superhard particle size and concentration greatly, and better processing quality can be obtained after several cutting of WEDM. The minimum sharpening allowance of PCD cutting tools can be controlled within 4~15μm after WEDM, and within 10μm for PCBN BNX20, while BZN6000 needs larger follow-up workload of sharpening.


2006 ◽  
Vol 532-533 ◽  
pp. 644-647
Author(s):  
Yi Ping Zhang ◽  
Jiu Hua Xu ◽  
Guo Sheng Geng

Ti-6.5Al-2Zr-1Mo-1V is a near alpha titanium alloy strengthened by solid solution with Al and other components. In this study, a series of experiments on tool wear and surface integrity in high speed milling (HSM) of this alloy were carried out. The tool lives under different cutting speeds were studied and the corresponding empirical equation of tool life was derived. Additionally, the wear mechanism of cutting tools was also discussed. Finally, surface integrity, including surface roughness, metallograph, work hardening and residual stresses, were examined and analysed. The result shows that good surface quality of workpiece could be obtained in HSM of the alloy.


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