Worm gears. Geometry of worms. Name plates for worm gear units, centre distances, information to be supplied to gear manufacturer by the purchaser

1999 ◽  
Keyword(s):  
Worm Gear ◽  
Worm Gears

Worm gear wear and coefficient of efficiency during their running-in period

2021 ◽  
pp. 22-25
Author(s):  
Keyword(s):  
Friction Coefficient ◽  
Velocity Vector ◽  
Worm Gear ◽  
Worm Gears ◽  
Contact Surfaces

The process of worm gear wear is considered. The reasons for the change in the coefficient of efficiency of worm gears during the running-in period are analyzed. Keywords: worm gear, line of engagement, contact surfaces, involute worm, velocity vector, friction coefficient. [email protected]

Calculation of the Digital Prototype for Modification of the Initial Straight Profile to the Form of the Tooth-Cutting Tool’s Producing Surface

2021 ◽  
pp. 35-46
Author(s):  
S. Ryazanov ◽  
M. Reshetnikov
Keyword(s):  
Cutting Tool ◽  
Worm Gear ◽  
Geometric Parameters ◽  
Kinematic Chains ◽  
Gear Cutting ◽  
Working Surface ◽  
Worm Wheel ◽  
Worm Gearing ◽  
Worm Gears ◽  
High Level

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].

scholarly journals Elastohydrodynamics of a Worm Gear Contact

2000 ◽  
Vol 123 (2) ◽  
pp. 268-275 ◽  
Author(s):  
S. Kong ◽  
K. Sharif ◽  
H. P. Evans ◽  
R. W. Snidle
Keyword(s):  
Film Thickness ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Worm Gear ◽  
Simulation Technique ◽  
Elastic Contact ◽  
Gear Teeth ◽  
Film Forming ◽  
Worm Gears ◽  
Gear Contact

The paper is concerned with prediction of elastic contact and elastohydrodynamic film thickness in worm gears. Using the undeformed geometry of the gap between gear teeth in contact a three-dimensional elastic contact simulation technique has been developed for calculation of the true area of elastic contact under load relative to the wheel and worm surfaces. A parallel investigation of elastohydrodynamic lubrication effects has been carried out using a special non-Newtonian, thermal solver which takes account of the nonsymmetrical and spin aspects of worm contacts. An interesting feature of the results obtained is the discovery of regions of poor film forming due to entrainment failure at the edges of the contact.

Numerical and Experimental Study of the Loaded Transmission Error of a Worm Gear With a Plastic Wheel

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Jean-Pierre de Vaujany ◽  
Michèle Guingand ◽  
Didier Remond
Keyword(s):  
Experimental Study ◽  
Transmission Error ◽  
Original Method ◽  
Worm Gear ◽  
Experimental Measurements ◽  
Structural Damping ◽  
Kelvin Model ◽  
Worm Gears ◽  
History Of ◽  
Generalized Kelvin Model

Nowadays, the wheels of worm gears with a low module can be made of plastic; thus, classical modeling can no longer be used satisfactorily. The present paper describes an original method for studying the quasistatic loaded behavior of a worm gear, with a steel worm and a nylon wheel. A generalized Kelvin model is proposed, and the computation of load sharing is described by using an equation of displacement compatibility. The history of previous deformation and the effect of the nylon’s structural damping are also taken into account. Experimental measurements of the loaded transmission error are performed with the help of optical encoders rigidly connected to the worm and gear shafts, giving access to their instantaneous angular positions. The numerical simulations fit quite well with the experimental results.

The Production of Small Worm Gears for Experimental Work

1947 ◽  
Vol 156 (1) ◽  
pp. 368-372
Author(s):  
A. M. Gunner
Keyword(s):  
Experimental Work ◽  
Research Laboratory ◽  
Single Point ◽  
General Rule ◽  
Worm Gear ◽  
Pressure Angle ◽  
Worm Wheel ◽  
Worm Gears ◽  
Shaft Angle ◽  
Gear Drives

Small worm gear drives are a common feature in the design of many types of apparatus, and the following description of the methods used for producing them in an experimental establishment may be of interest. Quantities are small, one or two to each pattern being the general rule, but there is certainly no lack of variety. The worms and wheels most often called for range in size up to 1½ inches and 6 inches diameter respectively, while pitches vary from 10 to 60 d.p. (diametral pitch). Addendum and dedendum proportions of 1/ PN and 1·25/ PN have been standardized, and a pressure angle of 20 deg. is adopted throughout. The gears are designed as hollow-faced helical (spiral) gears, and all calculations are based on the normal pitch. This is to enable standard hobs and cutters to be used for the worms. The shaft angle is usually 90 deg., but the angle of crossing may be varied up to 10 deg. either way on the particular machine employed for cutting the wheels. For many applications, backlash must be reduced to the very minimum consistent with smooth running; and to avoid the extreme accuracy of workmanship which an exact centre distance would necessitate, provision is usually made for adjustment of the worm. Although the Reinecker tangential feed method of worm wheel generation by a single-point tool —representing one tooth of a hob—is generally known, very little information on cutter forming is available. The method outlined was developed at the Admiralty Research Laboratory. Given the use of a modern worm grinder (not available), it should be possible to profile-relief grind these cutters after hardening.

Finite element modelling and load share analysis for involute worm gears with localized tooth contact

2001 ◽  
Vol 215 (7) ◽  
pp. 805-816 ◽  
Author(s):  
F Yang ◽  
D Su ◽  
C. R. Gentle
Keyword(s):  
Finite Element ◽  
Load Capacity ◽  
Worm Gear ◽  
Tooth Contact Analysis ◽  
Fe Modelling ◽  
Tooth Contact ◽  
Transmission Errors ◽  
Meshing Stiffness ◽  
Worm Gears ◽  
Gear Drives

A new approach has been developed by the authors to estimate the load share of worm gear drives, and to calculate the instantaneous tooth meshing stiffness and loaded transmission errors. In the approach, the finite element (FE) modelling is based on the modified tooth geometry, which ensures that the worm gear teeth are in localized contact. The geometric modelling method for involute worm gears allows the tooth elastic deformation and tooth root stresses of worm gear drives under different load conditions to be investigated. On the basis of finite element analysis, the instantaneous meshing stiffness and loaded transmission errors are obtained and the load share is predicted. In comparison with existing methods, this approach applies loaded tooth contact analysis and provides more accurate load capacity rating of worm gear drives.

The Thermal Rating of Worm Gearboxes

1944 ◽  
Vol 151 (1) ◽  
pp. 326-337 ◽  
Author(s):  
Harry Walker
Keyword(s):  
Temperature Rise ◽  
High Speed ◽  
Testing Machine ◽  
National Physical Laboratory ◽  
Worm Gear ◽  
Variable Load ◽  
Power Losses ◽  
Heating And Cooling ◽  
Physical Laboratory ◽  
Worm Gears

The paper deals with the factors affecting the temperature rise of totally enclosed self-lubricated gearboxes, with particular reference to worm gearboxes, and is based on observations obtained from a power circulating apparatus through worm gears which has provision for the accurate measurement of efficiency and temperature rise under variable load and speed. The theory underlying the heating and cooling of gearboxes is discussed, for gears running under continuous load and also under a repeated cycle of intermittent load. Temperature rise depends on the heat-dissipating capacity of the gearbox and the power losses within the box; heat-dissipating capacity is dealt with in relation to surface area of the box, speed of the gears, and artificial cooling by air fan; power losses are discussed under the headings of efficiency and oil drag losses. It is shown that gear speed and turbulence in the lubricant contribute considerably to heat-dissipating capacity, and that oil drag losses play an important part, particularly on large gears running at moderate or high speed. Cooling by air or other means is shown to result in an increase in power capacity (for a given allowable temperature rise) much more than in proportion to the increase in heat-dissipating capacity of the box, owing to a higher overall efficiency when transmitting heavier loads. Results of worm gear efficiency tests carried out in the past on the Daimler-Lanchester testing machine at the National Physical Laboratory on the author's design of worm gear, which gave the highest efficiency of any published tests carried out on this machine, are reconsidered in the light of recent work and it is contended that the National Physical Laboratory machine gives efficiency figures which are in general higher than the true efficiency.

Computer Aided Loaded Tooth Contact Analysis in Cylindrical Worm Gears

2004 ◽  
Vol 127 (5) ◽  
pp. 973-981 ◽  
Author(s):  
Vilmos Simon
Keyword(s):  
Contact Analysis ◽  
Worm Gear ◽  
Gear Pair ◽  
Contact Lines ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Computer Aided ◽  
Different Types ◽  
Worm Gears ◽  
Loaded Tooth Contact Analysis

A method for computer aided loaded tooth contact analysis in different types of cylindrical worm gears is proposed. The method covers both cases—that of the theoretical line and point contact. The geometry and kinematics of a worm gear pair based on the generation of worm gear teeth by a hob is presented. The full loaded tooth contact analysis of such a gear pair is performed. A computer program based on the theoretical background presented has been developed. By using this program the path of contact, the potential contact lines, the separations of mating surfaces along these contact lines, the load distribution and transmission errors for different types of modified and nonmodified worm gear pairs are calculated and graphically presented. The influence of gear tooth modifications on tooth contact is investigated and discussed.

Sign in / Sign up

Export Citation Format

Share Document