Papers by Keyword: Helix Angle

Abstract: Design an e-drive transmission gear, it is very crucial, to understand the failure modes since gears should be sized correctly to withstand loads that will expect to act on the gear teeth and make sure that still be within reasonable load-carrying capacity, compact and lightweight. Fatigue failure can happen on gears under repeated loading due to fatigue such as tooth root bending and contact stress of gear. Materials used in this study were two candidate alloy steels of Cr-Mo and Cr-Mo-Ni and methods employed to design the e-drive transmission gear were by iteration through KISSsoft gear simulation software as well as AGMA of Matlab script, it approaches various parameters such as helix angle, face-width, and input torque. Investigations on safety factors of root bending and contact, stresses of contact and bending, weight, compactness, quiet and smooth functioning have been done by altering the variable design parameters. To conclude that by increasing face width and helix angle both safety factors were increased uniformly regardless of the input torque as we calculated by both approaches. Similarly, the results showed that by increasing the helix angle and face width it brings to reduce the contact and bending stresses of transmission gear. As we comparing the results, the KISSsoft values are a little higher than the analytical (AGMA) values as proven in all fatigue of safety factors versus variable gear design parameter. Based on the safety factor, compactness, lightweight and quiet for smooth function of the designed e-drive mating gears are proven as the face width is 24.5 mm and the helix angle is 25^o.

Abstract: Drilling is the metal cutting process that are widely used in industrial sector such as in aerospace, automotive and manufacturing to produce a various of durable parts. Stainless steels in general are regarded as difficult to machine materials due to their high tendency to work harden; their toughness and relatively low thermal conductivity. In this research, the experimental setup for the effect of various parameters on drill performance in term of cutting force and surface roughness. Stainless steel 316L used as workpiece and uncoated tungsten carbide drill bit as the tool. From the experimental investigation, the results show that internal coolant with helix angle of 40 and feed rate of 0.1 mm/rev condition is the best drilling condition in term of thrust force and surface roughness. By observation on experiment, MQL coolant condition give highest thrust force while internal coolant is best condition to have most minimum force. For internal coolant, MQL and external supply, the optimum helix angle to obtain low surface roughness is 15° and 40°.

Abstract: AFRP(Aramid Fiber Reinforced Plastics) is widely used in the aerospace and automotive while there are many problems in machining AFRP such as furry, delamination, burns and so on. Milling experiments of AFRP have been conducted to study the influence of different helix angle (0°, 30°, 60°) and cutting tools (traditional end mill, multiple flute end mill and compression end mill) on cutting force and machined surface quality. The results indicated that the cutting force has been reduced and the surface quality has been improved with the increase of helix angle. The cutting tool structure can make greater influence on machined surface quality than the cutting parameters. A cutting tool with the structure of multiple flute or herringbone cutting edge could reduce the axial cutting force. However the cutting force is too small to cut off fibers when using a multiple flute end mill. A good processing surface can be achieved while cutting with a compression end mill or a tool with big helix angle.

Abstract: This paper proposed a kind of gearbox based on the toroidal drive to step up the speed of rotor rotation to a value suitable for standard induction generators for wind power field. In the inversion mechanism of the proposed gearbox, the system transmission ratio formula is obtained. Then the force analysis of the meshing components including a sun worm, a planet worm gear and an internal toroidal gear has been done respectively and the efficiency calculation formula of the gearbox system is deduced. Besides, the influences of the pressure angle and the helix angle of the sun worm and the internal toroidal gear for the gearbox have been further discussed. Finally, the verification of the efficiency analysis results of the gearbox is accomplished based on computer modelling and simulation.

Abstract: Recently, carbon fiber reinforced plastics (CFRP) are expected to be used more in the aerospace and automotive industries, because of their outstanding lightweight material characteristics and tensile strength [1][2]. Underlying this are problems closely related to improvement of the earth’s environment. However, a mechanical property is influenced by the difference in the distribution state of the carbon fiber, and the adhesion intensity of the binding material. Moreover, they have the characteristic of intense anisotropy, strength wise depending on the orientation of the carbon fibers [3][4]. Therefore, CFRPs are considered difficult-to-machine materials [5], because the surface finish deteriorates according to the carbon fiber orientation. Establishing the optimal cutting conditions to solve such problems also from an economical viewpoint is essential. In our study, end milling operations of different carbon fiber orientation CFRP composite material were investigated with three kinds of different helix angle end mills. Evaluations were based on the surface finish, cutting force and cutting temperature. Moreover, the relationships between the carbon fiber orientation and the machining operations were determined. We earlier evaluated the machinability from the relationship between carbon fiber orientation and tool helix angle by down-cut milling to solve these problems [6]. In this study, machining operations of different carbon fiber orientation CFRP composite material were investigated with three kinds of different helix angle end mills by up-cut milling. Evaluations were based on the surface finish, cutting force and cutting temperature. Moreover, the results of this experiment were compared with the results of down-cut milling.

Abstract: The main factors that cause the failure of gears are the bending stress and contact stress of the gear tooth. Out of these, failure of gears due to contact stress is high compared to bending stress. Stress analysis has been a key area of research to minimize failure and optimize design. This paper gives a finite element model for introspection of the stresses in the tooth during the meshing of gears. Specifically, helix angle is important for helical gears. Using modeling software, 3-D models for different helix angles in helical gears were generated, and the simulation was performed using ANSYS 12.0 to estimate the contact stress. The Hertz equation and AGMA standard was used to calculate the contact stress. The results of the theoretical contact stress values, using Hertz and AGMA are compared with the stress values from the FEA for different helix angles and the results are tabulated and discussed.

Abstract: The thin-walled component is mostly used in the aerospace industry. During machining the thin-walled components, deflection of wall occurs and causes the surface dimensional error. This paper focuses on the effect of end mill helix angle on the surface dimensional error and surface roughness when machining thin wall structure. End mills uncoated carbide were fabricated with a difference helix angle which are 25°, 30°, 35°, 40° and 45°. The results show, helix angle 35° produce smaller surface dimensional error and smoothest followed by 40°, 45°, 30° and 25°. The smaller helix angle provided high cutting force that causes more surface dimensional error due to chatter and reduction of contact time when then end mill engage with the workpiece material. Results from this research help to guide the machinist to machine thin-wall component with the right cutting tool.

Abstract: The current trend in the construction of gearboxes, regarding the speed increase, favors the increase of the dynamic loads which are accompanying the operation of these kinds of machines. The phenomena of dynamic contact like frictions, collisions and shocks which are taking place in cinematic couples, engines and mechanisms during their movement, are generating vibrations in a wide range of frequencies. Vibrations produced by gearboxes became characteristically indicators for assessing their quality. Therefore, the decrease of vibrations produced in the gear transmissions became lately a priority, being one of the combat methods in the fight against environmental pollution.

Abstract: A numerical simulation for heat exchanger with continuous helical baffles was carried out. The study focuses on the effects of helix angle on heat transfer characteristics. The results show that both the shell-side heat transfer coefficient and pressure drop decrease with the increase of the helix angle at certain mass flow rate. The latter decreases more quickly than the former. The tangential velocity distribution on shell-side cross section is more uniform with continuous helical baffles than with segmental baffles. The axial velocity at certain radial position decreases as the helix angle increases in the inner region near the central dummy tube, whereas it increases as the helix angle increases in the outer region near the shell. The heat exchange quantity distribution in tubes at different radial positions is more uniform at larger helix angel.

Abstract: To investigate the relationships between heat transfer coefficient and baffle helix angle of double-helical baffles heat exchanger, the physical and mathematical model of double-helical baffles heat exchanger with different baffles helix angle were developed and carried out. The researched results show that the optimization baffles helix angle results in the highest heat transfer coefficient of double-helical baffles heat exchanger; the inlet flow flux of shell side has no effect on the optimization baffles helix angle for those heat exchanger with same heat transfer structure; The optimization baffles helix angle tends to decrease with the tube diameter increment of double-helical baffles heat exchanger.