INTERNATIONAL. STANDARD. ISO. Second edition. Calculation of load capacity of spur and helical gears —. Part 2: Calculation of surface. ISO CALCULATION OF LOAD CAPACITY OF SPUR AND HELICAL GEARS – PART 2: CALCULATION OF SURFACE DURABILITY (PITTING). ISO FRENCH: French Language – CALCULATION OF LOAD CAPACITY OF SPUR AND HELICAL GEARS – PART 2: CALCULATION OF SURFACE.
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This part contains a summary of some theoretical information and formulas related to the geometry design, calculation of force and performance parameters as well as the strength control of involute gearing. These data were used in the calculations below. Some of the most important formulas for calculation of the gearing geometry are specified below. In the formulas, indexes 1 and 2 are used for a pinion and a wheel which is a pair: For the internal gearing ring geara negative value for the number of internal gear teeth is used, i.
In the case of planetary gearing, the individual gears are dependent on each other and the gearing must be handled as a whole, including the respective constraining conditions see below. Pinion and wheel parameters: Approaching and withdrawal of the production tool from the gear center changes the shapes and therefore also properties of the involute toothing. This creates corrected toothing. When determining values of corrections, first it is necessary to fulfill functional requirements for toothing, where the most important items include.
After securing function requirements, it is possible to further optimize corrections in order to improve one or more important toothing parameters. From the frequently used optimizing methods, it is possible to optimize the toothing in order to balance specific slips [5. For other optimizing processes there is a wide range of recommendations in professional literature, namely the so-called diagrams charts of limit corrections, providing a clear view of possibilities and selection of corrections.
SI units T [lb. Operating pitch diameter MK Base helix angle a wt Transverse pressure angle at the pitch cylinder. The losses in planetary gearing can be divided into losses due to idle run and losses due to loading. The losses due to idle run lubrication, unloaded mesh, bearings are difficult to specify analytically and in general, they are significantly lower than losses due to loading. The losses due to loading arise during power transmission and include:.
The loss coefficient can be approximately described according to the formula: The loss output can be determined from the relation: For the calculation of loss efficiency of the planet gearing, we will use the losses in the helical gearing carrier stopped with:.
Planetary gearings consist of a system of gearwheels and a carrier. The so-called suns are aligned with the carrier and the central axis of the gear mechanism.
The planets are the gearwheels mounted in a pivoting way on the carrier and they mesh with the suns or with each other. The planets may have one, two or more gearings. Two or multi-speed planets have more constructional variants with wider possibilities; however, they are more complex and expensive to manufacture. You can see an example of a simple planetary gearing with single-speed toothing of the planet below.
This basic type of planetary gearing is also handled in complex in this program.
That is used e. If one of the basic members 0 or 2 is connected to the frame, the system is called planetary gearing 1 degree of freedomspecifically a reductor in case of a drive outwards from the isk or a multiplicator in case of a drive outwards from the carrier. The system with the carrier connected to the frame is called a normal transmission or helical gearing.
Planetary gearings may be arranged in various ways. The most frequent way includes the serial arrangement, where the total transmission ratio efficiency is determined by the product of partial transmission ratios efficiency.
iso | dinesh kumar –
The composed gearings often use the possibility to brake individual members, i. With respect to the above-specified advantages, the use of planetary gearings is popular in a wide range of applications e.
The combination of planetary gearing with hydraulic or friction gearing is also common. With respect to the possibilities of assembly and functioning of planetary gears, the geometry of the gearwheels cannot be chosen at random. In order to provide proper functioning, the following several conditions must be followed iao observed. The planets of the planetary gearings gear with the suns, possibly with other planets.
This calculation applies to the joint mesh of a planet with suns planet, ring gear. As the planet and the ring gear have the same axis, the centre distance between the planet and both suns must be the same. It applies for the generally corrected wheels that: For simple planets and uniform planet distribution, the following condition must be complied with:.
This is a standard gearing calculation, where the rack is in gear with the pinion. The manufacturing tool profile can be specified both for the pinion and the gear rack. It is possible to select the number the pinion teeth, the pressure angle and the tooth slope. Since it has no meaning to correct the gear rack in this case, only the pinion correction is possible axial distance, gear condition and strength parameter improvement. In the calculation it is possible to enter the tangential force, which is the force of the gear rack acting on uso pinion, and the speed of the gear rack pinion circumferential speed.
These two values are then used to calculate the power and torque transferred via the pinion. Since 63366-2 is possible to use the gear rack for a range of various design solution, it is then necessary to calculate estimate and transfer the transmission requirements on these two values. The gear rack is replaced by a toothed wheel with a high number of teeth 1 teeth.
There is no specific methodology of specifying the critical speed for a gear rack application. As a rough estimate, the calculation of two toothed wheels may be used the gear rack is substituted by a toothed wheel. Enter the number of the pinion and gear rack loading cycles.
BS ISO 6336-2:2006
In the following paragraphs, the method of the bearing capacity calculation is described. The description includes the key formulas used as well as the notes important to understand the calculation and to operate this application. This text does not replace the full text of the standards used. This part of ISO presents the basic principles of, an introduction to, and the general influence factors for, the calculation of the load capacity of spur and helical gears.
The application factor, KA, is used to modify the value of Ft to take into account loads additional to nominal loads, which are imposed, on the gears from external sources. The empirical guidance values in table B. The internal dynamic factor KV makes allowance for the effects of gear tooth accuracy grade as related to speed and load. There are three calculation methods BC a C The method B is suitable for all the types of spur gears.
It is relatively complicated and may give completely unrealistic KV values, if the materials or the degree of accuracy are not properly selected.
Therefore it is possible to set the maximum limit for the calculation pre-set to 5. If this limit is exceeded, it is recommended to check the selected material in proportion to the gearing load. Method C supplies average values which can be used for industrial transmissions and gear systems with similar requirements in the following fields of application:. Method C can also generally be used, with restrictions for the following fields of application:.
Method C is different from C by adding the coefficient K3. Main resonance of gear with idler gears, inner gears and planet gears are calculated by different process. This coefficient takes into account the effect of the non-uniform distribution of load over the gear face. Uneven load distribution is caused by an elastic deformation of gears and housing, manufacturing deviations and thermal distortion. Methods, principles and assumptions are given in standard ISO Because the determination of the coefficient is dependent on a number of factors and primarily on the specific dimensions and design of the gearbox, is for the design purposes selected the coeficient KH b from graphs based on practical experiences.
The calculation is in paragraph . Detail description is in ISO Here is just a selection of formulas, information and comments that are related to the calculation KH b. Running-in allowance from graph. Component of equivalent misatignment.
It is possible to use several methods calculation, measurement, estimation. Ratio gear width to gear diameter Y Axis: Eh, IF, NT nitr. This part of ISO specifies the fundamental formulae for use in the determination of the surface load capacity of cylindrical gears with involute external or internal teeth.
It includes formulae for all influences on surface durability for which quantitative assessments can be made. Poisson ‘s ratio E 1, The work hardening factor, Z 63362- takes account of the increase in the surface durability due to meshing a steel wheel structural steel, through-hardened steel with a hardened or substantially harder pinion with smooth tooth flanks.
Dimensions and basic rack profile of the teeth finished profile A Determination of normal chordal dimensions of tooth root critical section for Method B A The stress correction factor Y S is used to convert the nominal tooth root stress to local tooth root stress. St, V, GGG perl. This part of ISO describes contact and tooth-root stresses, and gives numerical values for both limit stress numbers. It specifies requirements for material quality and heat treatment and comments on their influences on both limit stress numbers.
The three material quality grades ML, MQ and ME, stand in relationship to – ML stands for modest demands on the material quality and on the material heat treatment process during gear manufacture. The values of Ro, E and Poisson constant are commonly available. For the proposal of the tensile strength Rm and yield strength Rp0. Parameters for the time-strength curves were obtained from ISO and 3. These curves can be seen in a small graph in the calculation.