Grâce à l'analyse expérimentale de la sélection d'outils,usinage parameters and tool angles, the best solution for mirror surface usinage of copper alloy shaped grooves is finally arrived at, providing a theoretical basis and research foundation for improving the surface usinage quality of copper alloy parts.


1
With the improvement of the use performance of scientific and technological products and the growth of the use cycle, manufacturing enterprises have put forward higher requirements for the dimensional accuracy, geometric tolerance and surface roughness of product parts. In ultra-precision usinage, in order to ensure the roughness of the parts, most of them use grinding processing technology. However, copper alloy is a non-ferrous metal, and the material characteristics of non-ferrous metal determine that grinding processing is not suitable, and turning processing by lathe is appropriate. By analyzing the causes of the formation of surface roughness and combining with the actual processing experience, a set of turning methods to improve the surface roughness of the parts is summarized.

2Analyse de la structure de la pièce
A model of copper alloy material parts structure as shown in Figure 1, according to the design requirements, V-shaped groove and the inner circle coaxiality requirements φ0.01mm, surface roughness value Ra = 0.2μm. material for brass H62, the material has good mechanical properties, good plasticity, good turning performance, but there are sticky tool. The current existing usinage capacity of the factory makes the surface roughness value Ra of the part reach 0.8μm, which cannot meet the design requirements. Therefore, the processing technology of V-groove needs to be studied in depth to explore a suitable processing method to meet the production requirements.

Figure 1 Structure de la pièce en alliage de cuivre


3Solutions d'usinage
3.1 Mirror usinage technology turning and forming
(1) Tool The tool material currently used in the factory is mainly cemented carbide. Cemented carbide is made of tungsten-cobalt class (WC), tungsten-cobalt-titanium (WC-TiC), tungsten-titanium-tantalum (niobium) cobalt (WC-TiC-TaC) and other refractory metal carbides, which are pressed and sintered by powder metallurgical methods with metal binder Co (cobalt) or Ni (nickel). Cemented carbide has high hardness, wear resistance, better strength and toughness, heat resistance, corrosion resistance and a series of excellent properties, can be used for processing non-ferrous metals. It can be used for rough usinage when processing copper alloy V-groove.
In the field of non-ferrous metal mirror processing, diamond tools are one of the more commonly used. Diamond tools have the advantages of extremely high hardness and wear resistance, low friction coefficient, high elastic modulus, high thermal conductivity and low thermal expansion coefficient, as well as low affinity with non-ferrous metals, and not easy to produce chip tumors. In addition, due to the diamond elastic modulus, cutting cutting edge sharp, edge deformation is small, the non-ferrous metal extrusion deformation of the cutting is small, can make the cutting process in a small deformation to complete, so you can improve the quality of surface processing. Diamond tools mainly have: thin film coated tools, thick film diamond welding tools, diamond sintered tools and single crystal diamond tools. The copper alloy V-groove with an angle of 60° needs to be studied for the selection of tool angle in order to avoid interference during usinage. Considering the usinage cost as well as the test convenience, the machine clamp tool is used. As shown in Figure 2 and Figure 3, 35° and 45° inserts were used, and two types of fixtures were tested.

Fig. 2 Inserts 35° Fig. 3 Inserts 45°

(2) Machining parameters Machining parameters directly affect the surface roughness. In mirror usinage, the spindle speed will become the main factor affecting the surface roughness when the tool feed is reduced below a certain value. When the spindle speed is kept constant, the surface roughness increases rapidly when the turning depth is less than a certain value, while when it is greater than this value, the surface roughness shows an approximately linear increasing trend. The most appropriate depth of cut needs to be found for a particular material. Therefore, different process parameters need to be selected for experimental verification.
3.2 Usinage de rainures en V à l'aide de la technologie de polissage à la meule en tissu
L'usine actuelle de traitement anneau conducteur rainure en forme de V, la valeur de rugosité de surface peut atteindre Ra = 0,8¼m. afin de rendre la valeur de rugosité de surface de Ra = 0,2¼m, il peut être poli, avec roue en tissu, polissage plasma du laiton.
Le polissage de la roue en tissu est fait de tissu dans un type de roue utilisé pour polir. La dureté de la roue de polissage est déterminée par la distance de la ligne de suture, plus la distance de la ligne de suture est petite, plus la dureté de la roue de polissage est élevée. La roue de polissage peut être divisée en une roue en tissu entier non cousu, une roue en tissu refroidie par air et un type cousu. La roue en tissu entier non cousue est principalement constituée de tissu de coton doux et fin, adapté au polissage de pièces de forme complexe ou au polissage fin de petites pièces. La roue en tissu refroidie à l'air avec une méthode de coupe de ligne à angle de 45º est un pli en forme d'anneau, le milieu est équipé d'un disque en métal, avec les caractéristiques de ventilation et de dissipation thermique, adapté au polissage de grandes pièces. Type de couture principalement composé de tissu grossier, de tissu non tissé et de tissu plat fin, etc., la ligne de couture peut être de type cercle concentrique, type spirale et forme de rayonnement droite, adaptée au polissage de divers placages et à la forme de la pièce plus simple. Alliage de cuivre de polissage, vitesse circonférentielle de la roue en tissu couramment utilisée de 22 ~ 30 m / s, pour cette étude de la rainure en forme de V de l'anneau conducteur, les paramètres de traitement spécifiques doivent être testés.
3.3 Polissage plasma électrolytique
(1) recherche de polissage plasma électrolytique Le polissage plasma est la pièce et le fluide de polissage dans les ions métalliques détachés sous tension adsorbés sur la surface de la pièce, la pièce se heurte à l'impact du courant pour enlever le bloc, le flux de courant, le concave et le convexe changent constamment, la surface de la pièce est progressivement nivelée. La technologie peut améliorer efficacement la qualité de surface des pièces.
(2) Facteurs d'influence Pour le polissage plasma, les facteurs qui affectent la qualité du polissage de surface sont : la température de la solution, le temps de traitement, la concentration de la solution, la profondeur de plongée, le débit de solution, etc. La société dispose actuellement d'équipements de polissage plasma, qui peuvent être testés en fonction des facteurs d'influence pertinents. La taille de la rainure en V de l'anneau conducteur de cette attaque est petite, nécessite un montage pour la fixation et, afin d'assurer la cohérence de l'ensemble du polissage de la pièce, doit également être modifiée en fonction de l'équipement, faire pivoter les pièces, de sorte que toutes les directions de l'anneau sont polies en place.

4 Déterminer le schéma de traitement
Le programme ci-dessus étudie principalement l'outil, ses paramètres de traitement peuvent être sélectionnés via la machine-outil, le processus est plus pratique. Programmez deux du traitement de la roue en tissu, peut faire référence à moins d'expérience, et la taille de la rainure en forme de V de la pièce est petite, pas facile à serrer. Le schéma trois de la technologie de polissage au plasma est une technologie plus avancée, l'équipement de l'entreprise peut être pleinement utilisé, mais le schéma pour assurer la cohérence de l'ensemble du polissage de l'anneau, il y a des problèmes de production de montage plus difficiles. Et la nécessité d'un grand nombre de tests sur les paramètres de polissage. Une analyse complète a conclu que la première option a été adoptée.
The main purpose of this study is to make the surface roughness value Ra of copper alloy V-groove reach 0.2μm mirror effect. In the field of mirror surface processing of non-ferrous metals, diamond tools have better characteristics. During the implementation of the project, the more advanced mirror surface turning technology in the industry was investigated, researched and analyzed together with tool manufacturers, and customized suitable tools for processing tests. The usinage test was carried out mainly in terms of tool feed, spindle speed, depth of cut and programmed usinage method. Combined with the part material brass H62 and the mirror usinage theory, the optimal parameters were found to achieve the mirror usinage effect with the surface roughness value Ra=0.2μm of the part, and the batch production was verified according to the explored parameters.
4.1 Mirror usinage tool research
According to the usinage scheme, the mirror usinage tool is investigated. The surface roughness of the part usinage is influenced by the usinage parameters, the main and sub-deflection angles of the turning tool, and the material and structure of the tool is also an important influencing factor.
The cutting edge of PCD (polycrystalline diamond) material consists of many microscopic crystals, and the tool with ultra-microscopic particles helps to reduce the surface roughness value of the part during the usinage process.
The V-groove angle of this attacked part is 60º. In order to avoid usinage interference and to meet the test of multiple usinage methods, MVVNN symmetric toolholder was selected, and machine clamping tool was used considering the usinage cost as well as the test convenience.
After research and analysis, Kyocera's ultra-fine grain PCD diamond inserts were selected for the usinage test. The insert model is VBMT110301NE KPD001 with a tip angle of 35º and tip R=0.1mm, as shown in Figure 4.
 
a) Face avant de l'insert Kyocera b) Côté latéral de l'insert Kyocera
Figure 4 Lame Kyocera
Superfine PCD diamond ensures tip strength, wear resistance, chipping resistance (toughness), and sharpness for stable, long-life usinage.
4.2 Essais d'usinage
According to the relevant usinage parameters affecting the surface roughness, group tests are conducted, mainly from the programmed usinage method, spindle speed, feed and depth of cut.
(1) Common usinage methods for factory usinage of V-groove type parts The common programming and usinage methods for usinage V-grooves in the workshop are the walking track type and the direct usinage by forming tool. Forming knife direct usinage has the characteristics of high processing efficiency, but the surface roughness of the machined parts is poor, and easy to damage the tool. Walking track usinage has the characteristics of consistent surface of parts, less axial force on parts, and can effectively ensure the coaxiality of parts. Therefore, this test programming processing method uses the walking track type.
(2) group test 1 first consider the protection of the diamond tool in the initial determination of usinage parameters test, first usinage cylindrical surface to feel the appropriate usinage parameters. Machining cylindrical surface, as shown in Figure 5, has reached the mirror effect. 2 according to the initial determination of usinage parameters for the test usinage of parts. In the test usinage process, in the thickness of the larger cylindrical processing V-shaped groove, when the part thickness size reduced to 0.8mm, there is a knife usinage trace problem, as shown in Figure 6. The preliminary analysis concluded that the vibration was caused by the thin wall thickness at the edge of the part. Therefore, the back draft and feed were gradually reduced and the speed was increased in the subsequent tests.3 After the improvements were made according to the problems that appeared above, the machined surface of the V-groove was greatly improved, but there were still spots, as shown in Figure 7.

Figure 5 Usinage de surface cylindrique

Fig. 6 Tool usinage marks

Figure 7 Taches de surface
After analyzing the usinage path and parameters, and considering that the diamond tip is worn during rough usinage, the carbide tool is selected for rough usinage by re-calibrating the programming. Reserve 5mm usinage allowance, then use diamond tool for finishing, choose spindle speed 1200r/min, feed f=0.03mm/r, for usinage test. The surface of the V-groove of the part is smooth without spots, the tool marks are even, and the mirror effect is achieved (see Figure 8). The consistency of batch usinage is good, and the surface roughness value reaches Ra=0.0638μm by the surface roughness instrument, as shown in Figure 9, which meets the requirements.

Figure 8 Effet miroir

Figure 9 Rapport d'inspection de rugosité


5 Conclusion
A travers ce qui précèdemultiple part usinage tests, the surface roughness of the part is greatly influenced by the tool and usinage parameters. In the verification, the V-groove structure is continuously optimized, and the combination of tool and usinage parameters is improved, and finally the surface of V-groove achieves the mirror effect. And the dimensional accuracy of the part is stable and the surface quality is consistent in batch usinage, which achieves the target of the attack. By using super fine PCD diamond tools and MVVNN symmetric shanks, the mirror surface usinage parameters were determined through experimental research, and the parameters and usinage ideas can be extended to other parts that need to achieve the mirror surface effect to effectively improve the quality of the parts.