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Introduce the parameters and characteristics of Worm Gear
Worm gear shaft used to transmit motion between two staggered and motivation. Where between worm and worm gear and rack equivalent plane , the worm has a similar shape with the screw .
Basic Parameters
Modulus m, pressure angle, worm diameter factor q, lead angle , Worm Head , turbo teeth , addendum coefficient ( take 1 ) and headspace coefficient ( , 0.2 ) . Wherein the modulus number m and the pressure angle is the angle of the worm shaft surface modulus and pressure angle, i.e. the turbine end of the module and the pressure angle , and are the standard values ??; worm worm diameter coefficient (q) of the pitch circle diameter of its modulus the ratio of m.
Classification and conditions1.Middle plane of the worm and worm wheel modulus and the pressure angles are equal, that is the end surface of the worm gear worm modulus equal axial modulus and the standard value ; worm pressure angle should be equal to the end surface of the worm pressure angle of the axial plane and is standard value, namely m ( pole ) == m ( round ), ¦Á ( pole ) == ¦Á ( round ).
2.When the worm stagger angle is 90 ¡ã , the need to ensure , and worm and worm screw Worm line rotation must be the same .
Geometry calculation and cylindrical gears basically the same, should pay attention to several issues1.Is a worm lead angle ¦Ã on the worm helix indexing cylinder tangent angle between the end of the worm , and the relationship between the screw helix angle , the helix angle of the worm gear , the transmission efficiency large , when the engagement between the teeth is less than equivalent friction angle (¦×v = arctan fv, ie equivalent friction factor friction angle is equal to the arctangent , when ¦×v less than ¦Ã when , institutional self-locking.
2.The introduction of the worm diameter coefficient (q) is to limit the number of worm hob , so that the pitch circle diameter of the worm standardized m is constant , q large then large , the rigidity and strength of the worm shaft increases accordingly ; constant , q small is lead angle increases, the transmission efficiency is increased accordingly.
3.Worm Head recommended value is 1,2,4,6 , when to take a small value, the transmission ratio, and has a self-locking ; when taking large value, high transmission efficiency.Cylindrical gear with different institutions worm worm gear ratio is not equal to the ratio of the diameter of the worm gear diameter.
4.In the worm gear worm gear shift method of determining , according to the meshing point K in the direction , the direction ( parallel to the tangent of the helix ), and should be perpendicular to the axis of the worm wheel to determine Videos velocity vector triangle ; also can be " right hand left hand worm , L- worm right hand , four fingers thumb " to determine.
Character of the body1.Can get great gear ratio than the crossed helical gear mechanism compact.
2.Two tooth surfaces in line contact , its carrying capacity is much higher than crossed helical gear mechanism.
3.Worm drive screw drive equivalent , for the multi-tooth meshing , so the smooth transmission, noise is small.
4.With self-locking . When the lead angle of the worm gear teeth meshing between the equivalent of less than the friction angle, with a self-locking mechanism , enabling reverse self-locking, which can only be driven by a worm worm , and not driven by a worm gear worm . As used in lifting self-locking worm gear , the reverse self-locking can play a security role.
5.Transmission efficiency is low, severe wear . Worm gear transmission , the meshing teeth relative sliding velocity between the large , so friction losses and low efficiency . On the other hand , the relative sliding velocity Ambassador severe tooth wear , severe fever , in order to reduce heat and wear, often using more expensive antifriction material with good abrasion resistance and good lubricating device , and thus higher costs .
6.Worm large axial force .
ApplicationWorm and worm wheel is often used two axes staggered, transmission ratio, transmission power is small or intermittent occasions.
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Article tags: Worm Gear ,Worm Gear units,Gear,Power Transmissions.
