Meet Highest Precision At HSOAR Cycloid

Meet Highest Precision At Cycloid

Background

Two months ago, I ever heard someone said on Youtube, that software engineer would have a brighter future and would recommend university students to become, that is not true, a mechanical engineer can architect brilliant robot to rewrite the robot history!

Interestingly, I also carried out a poll on LinkedIn in two different groups, the topics are the same,

“Do you think AI more crucial than engineering?”

Some say more important, some disagree, but 45%-49% take they are both important!!

Robots are like human, Noble Spirit must be based on a sound, well-built physique. Mechatronics is the branch of science that consolidating hardware and mechanical designing.

Where there is a motor, there usually comes with a reducer.

As we all know, three key components of industrial robot, Motor, gearbox, controller,  their costs constitute 70% of a robot , the Most key component of the robot, the reducer, among the most difficult technology entrance for an enterprise, it even holds 36% of total cost. As far as the robot system is concerned, the precision reducer business is the most central profit source in the whole robot industry chain.

Mechanical design engineer wants to select a good gearbox for its model unit, robot axis, to enlarge torque and reduce speed to let the robot perform with high precision as well as good rigidity and dexterity!!

High precision planetary gearboxes are significant for industrial automation development.  They are a central element in the drive train of production machinery and play a central part in the performance of machines and systems.

Major features of robot motion

As we have known, most of robots perform repetitive tasks at high speed, like pick and place, assembly, welding, grinding in 3C industries etc, motion features short range, highly reciprocated, long term, load taking, instead of a low speed, perfect and complete 360 degree roundabout motion track.

Importance of High Precision throughout Service Life

For example, As we all know, airplane assembly is the most important stage during aircraft manufacturing, which exhibits a country’s comprehensive strength, statistics show that among plane accidents, 70% are due to linkage position uneffectiveness, 80% fatigue cracking are found at connected ports, so the safety is mostly dependent on the quality of drilling and riveting.

Since human operation is difficult to satisfy the drilling positioning accuracy, industrial robots are applied on airplane assembly frequently, thus the gearbox accuracy majorly influence the performance of a robot on such types of operations.

Consistency and stability of high accuracy performance is very important throughout robot operation, we hope a Robotic gearbox at zero backlash remains as forever as possible, both absolute positioning accuracy and positioning repeatability are firstly important for a robotic movement.

Take food industry as another example, the industry is developing towards the direction of high quality, high precision, large-scale and automation; high-end gearboxes that constitute high-end food packaging and processing devices are then naturally becoming more and more important.

Good gearboxes, such as high-quality meat grinder gearboxes, can directly exert great influences on the working efficiency, product cost, and product quality of the whole production and packaging line.

Difficulties for High Precision

While people have met various of difficulties on the way to embrace perfect accuracy and highest precision,

l Complex structure and many parts in motion

High accuracy is obtained through complicated reduction mechanism, even 200 parts involved in! This puts forward highest entrance for manufacturing and precision machining techniques.

l Unsteady and shorter retention

Some gearboxes have good precision, very low backlash at the beginning, when time goes by, the accuracy level also degrade quickly. Not all elements are participating in motion.

When excessive torque is applied while the gear is in motion, the teeth may not engage properly, cause non-eccentric motion, result in shortened life and a fatigue failure, teeth wear excessively. Or some parts may experience plastic deformation, some part buckles to cause early failure of gear.

Vibration can occur when the driving frequency of the servo system including the gearbox is at or close to the resonant frequency of the system.

When time goes by, visible tooth crack, rim crack, pitting, interface wear, wave generator wear, diaphragm crack, red cross section crack etc appear physically.

Some gearboxes perform tooth profile modification, The purpose is to try to ensure smooth meshing, even though there may be small manufacturing errors, and the teeth may deflect under load. It is recognized that under zero or light load the teeth will not be exactly conjugate.

l Lubrication and Viscous friction

Traditionally, it is extremely important to properly grease the component. There are two types of lubrication, oil and grease lubrication, You must know clearly when to replace grease, the wear characteristics of the gear are strongly influenced by the condition of grease lubrication. The condition of the grease is affected by the ambient temperature. various temperatures allow different input rotations. You will need to avoid mixing different kinds of grease/also precaution for special environments and pay attention to grease leakage.

Viscous friction occurs due to lubricant action. This type of friction results from the churning and mixing of lubricant-greatly depends on rpm speed.

At low rotation, this friction may be negligible, once the gearbox starts to turn, viscous friction increases significantly as rpm speeds up. For example, at an input of 200rpm, viscous friction is the largest contributor of overall friction.

l Higher cost

Some gearboxes manufacturer offer different design or solution such as software to assist to obtain higher precision, such as using special processing machinery, latest machine tools, techniques, or using helical gear, bevel gear, combinations to replace spur gear, this structure cause higher cost on design and material, production.

Higher precision will be created through rather more expensive machinery, price will be higher,

l Longer delivery time

Some gearboxes may have classified accuracy level, for example, standard backlash: P2 level ( 《5-7 arcmin）

Reduced backlash shown as P1 ( 《3-5 arcmin)

Micro backlash, say P0 level ( 《1-3 arcmin)

For gearboxes with micro backlash, manufacturer will generally need to wait for a longer lead time than gearboxes with standard backlash.

l Larger speed ratio using multiple-stage

When high precision planetary gearboxes goes to larger ratio, you will need to connect several gear pairs one after another, design usually turns to multi-stage, and more complex.

Such as ratio between 12~100, higher backlash occur, larger ratio result in chunky body, bigger size and volume which eyes can see, hands can feel.  

Overall multiplication factor of multi-stage gearboxes is calculated by multiplying the ratio of each gear stage, A three-stage gearbox is obtained by means of increasing the length of the ring gear and adding another planet stage.

As the number of gear stages increases, the efficiency of the overall gearbox is reduced. 

l High precision did not cover all items

High accuracy and zero backlash, means within 《3 arcmin are not commonly covering all series of products of a gearbox manufacturer, some items may have as per customer’s request, most of them may not.

Now Above Difficulties Removed?

Precision Cycloidal reducer is the recommended gearbox that provides the outstandingly excellent accuracy and repeatability, through its innovative Full-contact, All-involve simple steel-ball-rolling cycloidal mechanism .

This zero backlash structure achieves perfect precision, keeps strong stiffness, shows longer stable service life, esp. suitable for high precision robotic and automation areas.

Now Precision Cycloidal replace planetary gearbox has been mass-produced, with great advantages, A-Stage reduction ratio of up to 10,000, very high precision and longer retention time than other reducers, and the price is also unmatched by many reducers.  

Since HSOAR gearboxes sell to Japan and APAC, Germany with many shipments and QA PASS, they are expanding network world wide now, would you like to join the network?

About the Author

Starrick Li

Now take charge of Overseas BD in HSOAR Precision Robotics from 2019.

Contact Starrick Li at starrick.li@pcngb.com 

En.china-hsoar.com