Possible Ways of Reducing the Number of Gears in Universal Gear Units

This paper analyzes possibilities of reducing the number of necessary gears in the family of universal motor gear reducers with helical gears, since both the production and storage of a large number of different gears cost a lot and impose a great burden for any gear manufacturer, as it can be seen from literature [1,2] that focuses on this problem. The paper particularly emphasizes the necessity of narrowing down the assortment of gear reducers and the possibility of changing the design solution between the pinion and the electric motor as they represent the basic possibilities for reducing the number of necessary gears. The paper also points out the need for a special selection of preferred gear ratios and corresponding gears as one of the possibilities for reducing the total number of gears. This can certainly result in faster delivery of a gearbox with the preferred gear ratio

Possible Ways of Reducing the Number of Gears in Universal Gear Units

This paper analyzes possibilities of reducing the number of necessary gears in the family of universal motor gear reducers with helical gears, since both the production and storage of a large number of different gears cost a lot and impose a great burden for any gear manufacturer, as it can be seen from literature [1,2] that focuses on this problem. The paper particularly emphasizes the necessity of narrowing down the assortment of gear reducers and the possibility of changing the design solution between the pinion and the electric motor as they represent the basic possibilities for reducing the number of necessary gears. The paper also points out the need for a special selection of preferred gear ratios and corresponding gears as one of the possibilities for reducing the total number of gears. This can certainly result in faster delivery of a gearbox with the preferred gear ratio

Analysis of Conceptual Solutions of Universal Helical Geared Reducers

Geared reducers are mechanisms designed to reduce the number of revolutions using geared elements and nowadays they present one of the most commonly used types of mechanical transmissions in mechanical engineering. Due to the different shapes of geared elements, there are different types of geared transmissions: helical, bevel, worm, special and combined transmissions.  This paper analyses only helical geared transmissions, since there is a great extent of whole this matter. Helical transmissions are analysed only with external helical gearing, since internal geared pairs represent a special and very large group of gears. Within the external helical geared transmissions, only torque transmissions are analysed, while the transmissions of motion are not analysed and they represent another large group of transmissions. Only universal gear reducers with axial, or almost-axial, parallel shafts are considered (two-stage and three-stage transmissions). Although, single-stage gear reducer produced with parallel shafts are not considered by the paper in order to reduce the area of researching. Gear reducers are most commonly delivered to customer with electric motor, known as motor geared reducer, and they are studied here extensively. Gear reducer can be also delivered without motor, only with input shaft. The basic aim of this paper is to present all characteristics and specificities of motor geared reducer in one place

Selecting the Size of the Universal Reducer, Taking into Account its Thermal Load Capacity

Universal helical gear motors are among mechanisms that operate with a very high efficiency (about 0.98 per gear pair) [1, 2] and thus their thermal power capacity has not received enough attention, even in the cases when they overheat (usually at higher ambient temperature and high power motors). Therefore, it is necessary to define the thermal capacity in the catalogues of the speed reducer with a solid input shaft, as it is done by worm and helical-worm gear units which operate with much lower efficiency. Some manufacturers [3] pay necessary attention to this factor and thus enable the proper selection of gear reducers; this means they have prepared certain procedures to be undertaken if such occasion occurs, in order to overcome possible problems that may arise due to overheating the gear reducer. With this approach in the universal gear unit selection, some positive benefits can be surely achieved in the market of gear reducers, and that should not be ignored

Optimization of HCR gearing geometry using generalized particle swarm optimization algorithm

Posebna vrsta osnovnog evolventnog profila nestandardnog ozubljenja zove se ozubljenje s visokim stupnjem prekrivanja (HCR-ozubljenje), kada je stupanj prekrivanja veći uvijek su barem dva para zubi u dodiru (εα ≥ 2) i gdje jedinica dopune visine nije jednaka onoj za standardno ozubljenje, tako da se visina zuba povećava i veća je od jedan ha* > 1. Kada se rabi HCR-ozubljenje, nije potrebno postići veći kapacitet opterećenja zupčanika, ali ipak postoji veći rizik od smetnji zbog veće visine zuba. Prednost HCR-ozubljenja je veća otpornost (razdioba opterećenja se dijele na više parova zuba u isto vrijeme) i niža razina relativne buke ozubljenja, koja se može značajno smanjiti uporabom stupnja prekrivanja εα koji je cijeli broj. HCR profili su složeniji od standardnih evolventnih profila, oni imaju veću sklonost za pojavu smetnji, istaknut vrh debljine, ali i potkopavju zub tijekom proizvodnje (primarna proizvodna smetnja). Zbog povećanog dodatka visine, postoji veća mogućnost da se javljaju neke smetnje ili zašiljeni vrh zuba. Zato treba spriječiti ove pogreške i provjeriti jesu li sve jednadžbe i ograničenja zadovoljeni. Dana metoda pronalaženja optimalnih rješenja za h*a1, h*a2 i x1 koristi generalizirani algoritam optimizacije roja čestica (GPSO algoritam) i MATLAB kao program za optimizaciju. Ova optimizacija roja čestica je vrlo brz i pouzdan način.Special kind of basic involute profile of non-standard gearing is called high contact ratio (HCR) gearing, when the contact ratio is higher and there are always at least two pairs of teeth in contact (εα ≥ 2) and where unit addendum height is not equal one like for standard gearing, so the tooth height is increased and it is bigger than one ha* > 1. When HCR gearing is used, it is not necessary to achieve a greater gear load capacity, but nevertheless there is a greater risk of interference due to a greater height of tooth. Advantage of the HCR gearing is also a higher resistance (load distribution is shared on the more pairs of teeth at the same time) and lower relative noise level of gearing, which can be significantly reduced by using integer HCR factor εα. HCR profiles are more complicated than standard involute profiles, they have greater predisposition for occurring interference, pointed tip thickness, but also undercut of teeth during the production (primary production interference). Due to increased addendum height, there is larger possibility of occurring some interference or pointed tooth tip. Therefore it should prevent these errors and check if all equation and constraints are satisfied. The given method of finding optimal solutions for h*a1, h*a2 and x1 uses Generalized Particle Swarm Optimization Algorithm and MATLAB as a program for optimization. This GPS optimization is a very fast and reliable method

Consistency analysis of mechanical properties of elements produced by FDM additive manufacturing technology

Additive manufacturing (AM) technology refers to the process of producing 3D objects by adding material insuccessive layers. Fused deposition modeling (FDM) is one of the AM technologies where objects are builtby adding layers of melted thermoplastic filament onto the printing surface. Mechanical properties of FDMprinted part depend on many influencing factors such as material composition, extruding temperature,printing parameters and environment temperature.The aim of this study was to investigate consistency of mechanical properties of elements produced by FDMadditive manufacturing technology. To do so, mechanical tensile and compression tests were conducted onten samples using polylactic acid (PLA) and ten samples using acrylonitrile butadiene styrene (ABS)thermoplastic material. Tensile tests were conducted using Shimadzu Compact Tabletop Testing MachineEZ-LX and the compression tests were done using VEB ZDM 5/91 testing machine. The ultimate tensilestrength, strain, Young modulus and compression yield strength values were analyzed. The ABSthermoplastic material showed greater consistency in mechanical properties during tensile tests. Tensilestrength values for PLA material varied between samples thus showing greater inconsistency in repeatabilityof mechanical properties. Compression tests, on the other hand, showed that PLA samples had greaterconsistency in mechanical properties compared to ABS samples.Keywords: additive manufacturing, FDM, mechanical properties

INFLUENCE OF THE TEETH NUMBER ON THE GEAR MODULE VALUE AND LOAD CAPACITY OF GEAR PAIR IN UNIVERSAL HELICAL GEAR DRIVES

The basic parameters of the universal gear drives, except the axis height, are not defined by the standard, so the manufacturers of universal gear reducers can define them in their way. Most of the manufacturers followed the parameter values of universal gear reducers of leading world producers in order to ensure their interchangeability and the better positioning of their gear units at the market. This paper deals with the analysis of the influence of the gear pair teeth number on the size of the module, as well as on the load carrying capacity of single-stage universal gear units. For defined gear ratio values, different combinations of teeth number of pinion and driven gear were selected. Further, it was made calculation of the basic geometric dimensions of the gear pair, as well as the load capacity

Causes Analyse of Breakages of Foundation Screws

The paper deals with problematic of gear units and machine foundating and consequences that occur by foundation screws releasing. Namely, reliable operating of gear units, as well as other stationary machines, requires properly foundating. However, after certain period of time, relaxation of screw material, self-untightening of nuts and looseness of foundation screws influence on reducing the force of preload screw tightening and unequal load distribution. This unequal load distribution causes unequal deformations, which generate occuring vibrations. In extreme cases, breakages of screws and heavier accidents of systems driven by that gear units or machines can happen. With this paper authors want to indicate influence of deterioration degree on its load capacity