Cylindrical Worm Gear Research Articles

Manufacturing Method for Large Cylindrical Worm Gear Set of ISO Type I on Universal CNC Machine Tools

Large cylindrical worm gear set of ISO type I are manufactured using endmill tools on universal CNC machine tools. This manufacturing method requires neither special gear-generating machines nor special tools. The tooth flank forms of ISO type I cylindrical worm gears are involute helicoids as a standard. The targeted theoretical tooth flanks of the worm and the mating worm wheel are determined based on a tooth contact analysis (TCA) of such worm gear set. The cutting conditions of the worm are determined after the offset distance between the worm axis, and the central axis of the endmill tool is calculated. Afterward, the worm is manufactured by controlling only two axes on machine tools using a swarf milling method by use of the side of the endmill tool under the determined conditions. Meanwhile, the targeted theoretical tooth flanks of the mating worm wheel are modeled in 3-dimensional computer-aided design software, and the worm wheel is manufactured by a swarf milling method in a computer-aided manufacturing process. The comparison of experimental and analytical tooth contact patterns indicates almost no difference between the two tooth contact patterns.

Locus of lubricating weak point for the toroidal surface enveloping cylindrical worm drive

AbstractBased on the lubrication angle field and the locus of lubricating weak point, the lubricating characteristic of the toroidal surface enveloping cylindrical worm drive is globally investigated. The nonlinear equation system to determine the lubricating weak point is established by utilising the lubrication angle. Generally speaking, the weak locus always exists roughly in the middle of the tooth surface of cylindrical wormgear and a zone with worse lubricating behaviour is around the locus. By increasing the number of worm thread, the locus of lubricating weak point can be completely removed from the wormgear tooth surface, and the locus approximately is in the shape of the inverse capital letter L. On this occasion, the entire wormgear tooth surface is half surrounded by the locus, and the overall lubrication performance of the worm drive is improved. The current research is an application of elastohydrodynamic lubrication (EHL) on worm drive.

Calculation method for tooth thickness of cylindrical worm gear

Calculation method for tooth thickness of cylindrical worm gear

Расчет координат модифицированного профиля производящей поверхности зуборезного инструмента

Spatial helical gears, worm gears with a cylindrical worm, globoid gears, etc., are widely used in most of modern engineering products [1-3; 37; 42]. Cylindrical worm gears are actively used in the creation of metalworking equipment (push mechanisms of rolling mills, presses, etc.), in lifting and transport machines, in drives and kinematic chains of various machine tool equipment where high kinematic accuracy is required (dividing machine tools, adjustment mechanisms), etc.
 In a worm gear a cylindrical worm or its cylindrical helical surface can be cut by various technological methods [49-51], but no matter how the shaping of the worm gear elements’ working surfaces is carried out, the worm wheel is cut with a gear cutting tool, whose producing surface coincides with the worm thread’s lateral surface [19; 22; 23]. In this regard, the working surface of the cylindrical worm wheel’s tooth, even with a non-orthogonal arrangement of axes, is an envelope of a one-parameter family of surfaces that gives a linear contact, which presence makes it possible to transfer a large load using a worm gear.
 For high-quality manufacturing of worm gears, it is necessary to design and manufacture a productive gear cutting tool - an accurate worm cutter, whose shaping (working) surface must be identical to the profiled worm’s shaping (working) surface [24-27; 54].
 One of the most important tasks in the implementation of worm gearing is the problem of jamming of the cylindrical worm and the worm wheel’ contacting surfaces. This problem is excluded by relieving the contacting surfaces’ profile along the contact line. Considering that any violations of contacting surfaces’ geometric parameters affect the change in their geometric characteristics, the tasks of accurately determining the adjustment parameters of the technological equipment, used for shaping the worm and worm wheel, enter into in the foreground of the worm gearing elements production.
 In modern conditions of plant and equipment obsolescence, and in particular, of gear cutting machines used for worm gears manufacture, these machines physical wear, implies an inevitable decrease in the accuracy of their kinematic chains. Therefore, in order to maintain the produced gears’ quality at a sufficiently high level, it is necessary to use deliberate modification of contacting surfaces when calculating the worm gearing’s geometric parameters; such modification reduces the worm gear sensitivity to manufacturing and mounting errors of its elements [28-31].

Normal deformation and stress analysis of the tooth roots in case of different worm gear drives

The aim of this study is the comparative finite element analysis of the tooth roots of one tooth on worm-wheels having different geometries. Designing of various cylindrical worm gear drives is essential for the study where all of the input parameters are the same, only the number of thread on the worm is modified. Due to this modification the shape of the worm-wheels is different that is why dissimilar mechanical parameters will be received by the same load force. The creation of the CAD models is also important for the analysis.

Projektovanje veličine para cilindričnih pužnih zupčanika

A method for the design sizing task of cylindrical worm gearsets is presented that gives an estimate of the initial value of the normal module. Expressions are derived for the worm pitch diameter of integral and shell worms as well as for the active face width of the gear and the threaded length of the worm. An attempt is made to predict the contact strength of bronze materials against scoring resistance. Four Examples of design sizing tasks of cylindrical worm gears are carried out using the approach presented and the results are compared with previous solutions from other methods. The results for first three examples show excellent comparisons with previous solutions of American Gear Manufacturers Association (AGMA) method. The results of the fourth example are slightly more conservative than those of DIN3999 but are practically similar. Therefore, it appears that a systematic, reliable and more scientifically based method for cylindrical worm drive design sizing has been developed.

Designing and loaded tooth contact analysis of an Archimedean worm gear drive focusing for the connecting teeth of the worm wheel by loaded torques

The cylindrical worm gear drives are widely used in different mechanical construction such as in the vehicle industry, the robotics, the medical appliances etc. The main property of them is the perpendicular and space bypass axes arrangement. Quite high transmission ratio could be achieved because of the high number of teeth of the worm-wheel and a little number of threads of the worm. More teeth are connected on the worm-wheel at the same time that is why higher loads and power could be transferred. In this research an Archimedean type cylindrical worm gear drive was designed. After the determination of the geometric parameters the computer-aided models were created for the LTCA analysis. Knowing of the kinematic motions of the elements the contact points of the wrapping surfaces could be determined by mathematical way. The necessary coordinate system's arrangements and matrixes were also determined. Different torques were applied during the LTCA. The changing of the distribution of the normal stress and normal deformation into different directions was followed on each connecting tooth of the worm-wheel by the torques. Based on the results consequences were determined by the created diagrams which contain the torques and the analysed mechanical parameter for each tooth.

Machining method of large-sized cylindrical worm gears with Niemann profiles using CNC machining center

In this paper, a machining method of large-sized cylindrical worm gears with Niemann profiles using a computer numerical control (CNC) machining center is proposed. For this study, the tooth contact pattern and transmission errors of large-sized worm gear pair with Niemann profiles are analyzed before machining of the worm and worm wheel. Next, the machining conditions of worm are determined calculating each offset distance between the worm axis and the center axis of the end mill, and then the worm is machined by swarf cutting that means machining by the side surface of the end mill. The tooth profiles of worm wheel are modeled using a 3D computer-aided design (3D-CAD) system based on the analyzed results and the worm wheel is machined by swarf cutting through a computer-aided manufacturing (CAM) process. Afterwards, the axial tooth profile of the machined worm, and the tooth surface deviations and surface roughness of the machined worm wheel are measured. Moreover, the experimental tooth contact pattern is compared with analyzed one. As a result, the validity of the proposed machining method of the large-sized worm gears with Niemann profiles using a CNC machining center was confirmed.

Constructiv and Technological Consideration on the Generation of Gear Made by the DLP 3D-Printed Methode

The aim of the work is conduct to highlight how the technological parameters has influence of 3D printed DLP on the generation of wheel, made from resin type material. In the first part of the paper is presents how to generate in terms of dimensional aspects specific design cylindrical gears, conical and worm gear. Generating elements intended to reduce the cost of manufacturing of these elements. Also are achieve the specific components of this work are put to test with a laboratory test stand which is presented in the paper in the third part of the paper. The tested gears generated by 3D-printed technique made with 3D printed with FDM or DLP technique. After the constructive aspects, proceed to the identification of conserved quantities, which have an impact both in terms of mechanical strength, but his cinematic, in order to achieve a product with kinematic features and good functional domain specific had in mind. The next part is carried out an analysis of the layers are generated using the DLP and FDM method using an optical microscope with magnification up to 500 times, specially adapted in order to achieve both visualization and measurement of specific elements. In the end part, it will highlight the main issues and the specific recommendations made to obtain such constructive mechanical elements.

Globoid surface shaped with turning and envelope method

In industrial practice, cylindrical worm gears are most often used due to their feasibility. In the literature, much attention has been paid to determining the helical surface of worms of such transmissions. Globoidal worm gearboxes are much less frequently used due to technological difficulties. Come on, the globoidal worm ensures simultaneous cooperation of a larger number of teeth and the location of the teeth contact line is more favorable. Therefore, the following is an analytical method for the description of a globoid surface by turning and by a finger milling method.

Numerical Simulation-Based Optimization of Contact Stress Distribution and Lubrication Conditions in the Straight Worm Drive

Tooth contact area optimization/meshing of the straight worm pair is vital for improving its operation efficiency. Geometric parameters of a worm helicoid were derived via the gear meshing theory using the equations of the instantaneous contact line. The visualization function and powerful computing capability of MATLAB are used for the numerical analysis where the instantaneous contact line distribution is simulated for particular worm drive parameters, which yields the induced curvature and slip angle in the direction of the line. The above results are used for further optimization of the meshing performance of the straight worm gear and identification of its influencing factors. A case study of the particular cylindrical worm gear in compliance with the GB 10085-1988 Standard of China demonstrate that a reasonable selection of worm gear parameters can extend the contact line and the working range of the tooth surface of the worm gear and/or make the contact line distribution along the worm wheel more uniform, thus improving the local meshing performance.

Modelowanie procesu kształtowania ślimaków przekładni spiroidalnej

The article presents various methods of shaping cylindrical spiroid worm gear of asymmetrical outline using two tools. Cutting thread of worm gears is made on CNC lathes with blades in the form of universal inserts. Shows the geometric model and technological machining cylindrical worm gear spiroid on a CNC lathe. The correctness of the test results obtained in numerical developed program was tested through experimental studies of the process of cutting worm gears given parameters. Cutting process of worm gears was made on a lathe CTX210 using overlay ShopTurn in module for threading. The process uses a standard turning tool with interchangeable inserts and turning tools with a specially designed geometry. Studies performed on various cutting parameters and for a various materials of cutting inserts.

Principle and Practice of the Measurement for Hourglass Worms and Hobs

Compared with cylindrical worm gears, hourglass worm gears have better transmission performance. The measurement of the hourglass worms and the hobs is a critical issue to restrict the application of the hourglass worm gear transmission. To solve this problem, an hourglass worm and hob measuring principle and a measuring machine which achieves the inspection of each deviation are proposed. In this paper, the measuring principle is explained. The models of the deviations based on the cylindrical-coordinate system are determined. The machine controls the movement of the probe in accordance with the path created by the models. By checking the geometric deviations, including the helix deviation and the axial tooth profile deviation of the worm, and the cutting edge helix deviation and the cutting edge tooth profile deviation of the hob, the principle is proved to be feasible.

Modified worm gear hobbing for symmetric longitudinal crowning in high lead cylindrical worm gear drives

A single enveloping worm gear of cylindrical worm gear drive is cut by an oversized hob. The oversize provides a longitudinal crowning on the worm gear tooth surface. However, when a lead angle of the worm becomes higher, the longitudinal crowning becomes more asymmetric. The asymmetrically crowned worm gear surface makes the gear contact more sensitive to the certain direction of misalignment. To change the longitudinal crowning from asymmetric to symmetric, a method of modified worm gear hobbing is proposed. The modification uses a modified machine tool setting and a modified hob specification. A new hobbing mechanism or hob geometry is not required in this method. Results of the proposed modification are confirmed by using a surface separation topology based on differential geometry, and contact pressure analysis based on finite element method.

Load Capacity of Cylindrical Worm Gears According to DIN 3996-2012

Load Capacity of Cylindrical Worm Gears According to DIN 3996-2012

RANCANG BANGUN ALAT MIXER VERTIKAL ADONAN KUE DONAT DENGAN GEARBOX TIPE BEVEL GEAR KAPASITAS 7 KILOGRAM

Making doughnut in a small-scale industry generally has a problem with inappropriate equipment and easy to be broken like using hand mixer. In its gearbox, the cylindrical worm gear usually made of plastic so that will easy to worn. With the use gearbox type bevel gear made of metal, then the mixer would able to overcome the problem of dough mixing where the gearbox of this type can overcome the large load with high rotation, so that the capacity of the mixer can be enlarged so that it will increase the results of work productivity. The design method begins with observation of the impact of performance, efficiency, needs and ergonomics and then proceed with the design concept of the tool design, calculation of the construction of the tool and its components and the last phase is testing of the tool by trial and error. Calculations were made to the components that will be assembling such as axis, pegs, bearings, bevel gear and its gear ratio, then the construction framework of the mixer and the container for the dough to be stirred. From the calculation results obtained from the capacity of the hand mixer with the use of 7 kg / hour, the bevel gear mixer can improve productivity results with a larger capacity of 18 kg / hour or increased by 225% compared to hand mixer capacity.

RANCANG BANGUN ALAT MIXER VERTIKAL ADONAN KUE DONAT DENGAN GEARBOX TIPE BEVEL GEAR KAPASITAS 7 KILOGRAM

Making doughnut in a small-scale industry generally has a problem with inappropriate equipment and easy to be broken like using hand mixer. In its gearbox, the cylindrical worm gear usually made of plastic so that will easy to worn. With the use gearbox type bevel gear made of metal, then the mixer would able to overcome the problem of dough mixing where the gearbox of this type can overcome the large load with high rotation, so that the capacity of the mixer can be enlarged so that it will increase the results of work productivity. The design method begins with observation of the impact of performance, efficiency, needs and ergonomics and then proceed with the design concept of the tool design, calculation of the construction of the tool and its components and the last phase is testing of the tool by trial and error. Calculations were made to the components that will be assembling such as axis, pegs, bearings, bevel gear and its gear ratio, then the construction framework of the mixer and the container for the dough to be stirred. From the calculation results obtained from the capacity of the hand mixer with the use of 7 kg / hour, the bevel gear mixer can improve productivity results with a larger capacity of 18 kg / hour or increased by 225% compared to hand mixer capacity.

Study on the influence of gear hobbing and shaft misalignments on the geometric interference of cylindrical worm gear set

Geometric interference can occur in cylindrical worm gear set that makes use of oversized hob to cut the worm gear. In particular, the interference occurs easily in the design with high lead and low pressure angles. The interference results in a corner contact. In this study, we examined the influence of the machine tool setting errors of the worm gear hobbing and the influence of the shaft misalignments of the worm gear set on the interference. To determine the interference, we used the surface separation topology based on differential geometry. In addition, we also examined the hob oversize range required to avoid the interference under the condition of the machine tool setting errors and shaft misalignments. This study found that the interference can be avoided not only when the hob oversize is larger than the upper limit, but also when the hob oversize is smaller than the lower limit. This study also found that the interference can be avoided by applying the intended errors on the machine tool setting and shaft alignment, without manipulating the hob oversize.

Geometric interference in cylindrical worm gear drives using oversized hob to cut worm gears

This study examined the geometric interference of cylindrical worm gear drives using an oversized hob to cut the worm gear. The instantaneous line contact of a fully conjugated gear set becomes an instantaneous point contact when an oversized hob is used. In this type of worm gear drive, however, an edge contact can occur between the worm and worm gear. The edge contact is caused by geometric interference, and it occurs regardless of the presence of elastic deformation, misalignment, and transmission error. Aspects of the interference are presented through graphical illustrations. For examining the interference based on the differential geometry, two methods are proposed. The first method is for determining the surface separation topology between the tooth surfaces of a worm and a worm gear for an entire meshing cycle, and the second method for determining the boundary of the initially occurring area of interference when the hob oversize changes from zero to a nonzero value. By using the presented methods, the influence of various design parameters, such as the lead angle of the worm, the oversize of the hob, and the normal pressure angle, on the interference are examined and discussed through numerical examples.

Application of the general mathematical model for CAD modelling of cylindrical and conical worm gear drives

Based on the general mathematical model of Dudás [3, 4] — which is appropriate for mathematical modelling of production technology methods and various toothed gear pairs — we have generated mathematical models which are appropriate for determination of tooth surface points of face gear and worm gear connection with conical and cylindrical worm by numerical way. After doing the necessary calculations, the CAD models of the worm gear drives could be generated. Based on these there is an opportunity for rapid prototyping (RP) technology for other connection and production geometric analysis. For the verification of our calculated results, we generate CAD models of one to one given geometric conical and cylindrical worm gear drives for other analysis.