What are anti-backlash gears?
Example of anti-backlash gears
Backlash, which is the play between the tooth surfaces of mating gears, is needed for the deflection of teeth and expansion due to heat generation during gear operation, absorption of tooth profile errors, appropriate lubrication, etc.
In general, backlash is set by reducing the tooth thickness, increasing the center distance, etc.
On the other hand, machines that require high positioning accuracy demand very small (or zero) backlash gears.
In order to meet such demands, each gear manufacturer has developed gears with the names such as “anti-backlash gears”, “no backlash gears”, and “zero backlash gears” to accommodate the amount of backlash required according to the load.
In the case of spur gears, “gears with adjustable backlash amount” have a structure in which the position of two identical gears are overlapped and slightly shifted to control the tooth thickness in a pseudo manner.
Solution by KHK
When the machine is required to have accurate repetitive forward/backward movements, in order to suppress the rattling while the gears are in motion, the fastening portion (gear holes, shafts, keyways) must also be considered.
As for backlash countermeasures, KHK’s anti-backlash gears (spur gears) are basically the same as other companies’ designs by stacking the same two gears and meshing them with the mating gear while shifting them slightly (while controlling the tooth thickness in a pseudo manner).
On the other hand, KHK’s measures against rattling of the gear fastening parts (gear holes, shafts, keys) do not use keys but friction fastening using tapered rings.
As a result, the keys are not deformed (due to repeated forward and reverse movement) avoiding the deformation of the keys and rattling, and the rotation of the shaft is accurately transmitted to the mating gear.
However, the type of anti-backlash gear best suited depends on the usage situation of the customer. Please consult with KHK if you have any questions.
Anti-backlash gear using friction fastening structure
Anti-backlash gear where two gears of the same shape are stacked and slid slightly