Worm gears are usually used when large rate reductions are needed. The reduction ratio depends upon the number of starts of the worm and number of tooth on the worm equipment. But worm gears have sliding contact which is quiet but will produce heat and have relatively low transmitting efficiency.
For the materials for production, in general, worm is constructed of hard metal while the worm gear is made from relatively soft metal such as for example aluminum bronze. This is because the number of teeth on the worm equipment is relatively high compared to worm using its number of starts being generally 1 to 4, by reducing the worm equipment hardness, the friction on the worm the teeth is reduced. Another characteristic of worm manufacturing is the need of specialized machine for gear reducing and tooth grinding of worms. The worm equipment, on the other hand, may be made with the hobbing machine used for spur gears. But due to the various tooth shape, it is not possible to cut many gears at once by stacking the apparatus blanks as can be carried out with spur gears.
The applications for worm gears include gear boxes, angling pole reels, guitar string tuning pegs, and in which a delicate acceleration adjustment by utilizing a huge speed reduction is needed. While you can rotate the worm gear by worm, it is normally not possible to rotate worm by using the worm gear. This is called the personal locking feature. The self locking feature cannot continually be assured and a separate method is preferred for true positive reverse prevention.
Also there exists duplex worm gear type. When working with these, it is possible to change backlash, as when one’s teeth put on necessitates backlash adjustment, without requiring a alter in the guts distance. There are not too many producers who can create this type of worm.
The worm equipment is more commonly called worm wheel in China.
A worm gear is a gear comprising a shaft with a spiral thread that engages with and drives a toothed wheel. Worm gears are an old style of equipment, and a version of one of the six basic machines. Essentially, a worm equipment is definitely a screw butted against what appears like a standard spur gear with somewhat angled and curved teeth.
It adjustments the rotational motion by 90 degrees, and the plane of movement also changes due to the placement of the worm on the worm wheel (or just “the wheel”). They are typically comprised of a metal worm and a brass wheel.
Figure 1. Worm gear. Most worms (however, not all) are at the bottom.
How Worm Gears Work
An electric engine or engine applies rotational power via to the worm. The worm rotates against the wheel, and the screw face pushes on the teeth of the wheel. The wheel is usually pushed against the load.
Worm Gear Uses
There are some reasons why you might select a worm gear more than a standard gear.
The first one may be the high reduction ratio. A worm gear can have an enormous reduction ratio with small effort – all one must do is definitely add circumference to the wheel. Therefore you can utilize it to either significantly increase torque or help reduce speed. It’ll typically take multiple reductions of a typical gearset to achieve the same reduction level of a one worm gear – which means users of worm gears have fewer shifting parts and fewer areas for failure.
A second reason to use a worm gear is the inability to reverse the path of power. Due to the friction between the worm and the wheel, it is virtually unattainable for a wheel with force applied to it to begin the worm moving.
On a standard gear, the input and output could be turned independently once enough force is used. This necessitates adding a backstop to a standard gearbox, further raising the complication of the apparatus set.
YOU WILL WANT TO to Use Worm Gears
There is one particularly glaring reason why you might not choose a worm gear more than a standard gear: lubrication. The movement between the worm and the wheel gear faces is completely sliding. There is no rolling component to the tooth contact or interaction. This makes them fairly difficult to lubricate.
The lubricants required are often very high viscosity (ISO 320 and higher) and therefore are difficult to filter, and the lubricants required are typically specialized in what they perform, requiring a product to be on-site specifically for that kind of equipment.
Worm Gear Lubrication
The primary problem with a worm gear is how it transfers power. It really is a boon and a curse at the same time. The spiral movement allows large sums of decrease in a comparatively small amount of space for what’s required if a typical helical gear were used.
This spiral motion also causes a remarkably problematic condition to be the principal mode of power transfer. That is commonly known as sliding friction or sliding use.
With a typical gear set the power is transferred at the peak load point on the tooth (referred to as the apex or pitchline), at least in a rolling wear condition. Sliding occurs on either side of the apex, however the velocity is relatively low.
With a worm gear, sliding motion is the only transfer of power. As the worm slides over the tooth of the wheel, it gradually rubs off the lubricant film, until there is absolutely no lubricant film still left, and as a result, the worm rubs at the metallic of the wheel in a boundary lubrication regime. When the worm surface area leaves the wheel surface, it accumulates more lubricant, and starts the process once more on the next revolution.
The rolling friction on a typical gear tooth requires little in the form of lubricant film to complete the spaces and separate the two components. Because sliding occurs on either part of the gear tooth apex, a slightly higher viscosity of lubricant than is definitely strictly necessary for rolling wear must overcome that load. The sliding occurs at a relatively low velocity.
The worm on a worm set gear turns, and while turning, it crushes against the strain that’s imposed on the wheel. The only way to avoid the worm from touching the wheel is usually to get a film thickness large enough to not have the whole tooth surface area wiped off before that area of the worm is out of the load zone.
This scenario requires a special kind of lubricant. Not only will it will have to be a comparatively high viscosity lubricant (and the higher the strain or temperature, the higher the viscosity should be), it must have some way to help overcome the sliding condition present.
Read The Right Way to Lubricate Worm Gears to find out more on this topic.
Viscosity is the major aspect in avoiding the worm from touching the wheel in a worm gear set. While the load and size of gearing determines the mandatory lubricant, an ISO 460 or ISO 680 is fairly common, and an ISO 1000 is not unheard of. If you’ve ever really tried to filter this range of viscosity, you know it is problematic because it is most likely that none of the filters or pumps you have got on-site would be the proper size or ranking to function properly.
Therefore, you would likely have to get a specific pump and filter for this kind of unit. A lubricant that viscous requires a sluggish operating pump to prevent the lubricant from activating the filter bypass. It will require a large surface area filter to permit the lubricant to circulation through.
Lubricant Types to consider
One lubricant type commonly used in mixture with worm gears is mineral-based, compounded equipment oils. There are no additives that can be put into a lubricant that can make it get over sliding wear indefinitely, however the natural or synthetic fatty additive combination in compounded gear oils results in great lubricity, providing a supplementary measure of protection from metal-to-metal get in touch with.
Another lubricant type commonly used with worm gears is mineral-based, commercial extreme pressure (EP) equipment oils. There are some problems with this kind of lubricant in case you are using a worm equipment with a yellow metallic (brass) component. However, in case you have relatively low operating temps or no yellow steel present on the gear tooth surfaces, this lubricant works well.
Polyalphaolefin (PAO) equipment lubricants work very well in worm gear applications because they naturally have got good lubricity properties. With a PAO gear oil, it’s important to watch the additive package, because these can possess EP additives. A standard-duty antiwear (AW) fortified gear oil will typically become acceptable, but be sure the properties are appropriate for most metals.
The author recommends to closely view the put on metals in oil analysis testing to ensure that the AW package isn’t so reactive as to trigger significant leaching from the brass. The effect should be much less than what would be seen with EP also in a worst-case scenario for AW reactivity, nonetheless it can show up in metals examining. If you want a lubricant that can manage higher- or lower-than-typical temperatures, the right PAO-based product is probable available.
Polyalkylene glycols (PAG), a fourth type of lubricant, are becoming more prevalent. These lubricants have excellent lubricity properties, , nor contain the waxes that trigger low-temperature problems with many mineral lubricants, producing them an excellent low-temperature choice. Caution should be taken when using PAG oils because they are not compatible with mineral oils, and some seals and paints.
Metallurgy of Worm Gears
The most typical worm gears are created with a brass wheel and a steel worm. That is since the brass wheel is normally easier to replace than the worm itself. The wheel is manufactured out of brass since it is designed to be sacrificial.
When the two surfaces come into contact, the worm is marginally secure from wear since the wheel is softer, and for that reason, the majority of the wear occurs on the wheel. Oil analysis reports on this kind of unit almost always show some level of copper and low degrees of iron – because of this of the sacrificial wheel.
This brass wheel throws another problem into the lubrication equation for worm gears. If a sulfur-phosphorous EP gear essential oil is placed into the sump of a worm gear with a brass wheel, and the temperature is high enough, the EP additive will activate. In regular metal gears, this activation generates a thin coating of oxidation on the top that helps to protect the gear tooth from shock loads and various other extreme mechanical conditions.
On the brass surface however, the activation of the EP additive outcomes in significant corrosion from the sulfur. In a short timeframe, you can drop a substantial portion of the strain surface area of the wheel and cause major damage.
A few of the less common materials found in worm gear pieces include:
Steel worm and steel worm wheel – This software does not have the EP complications of brass gearing, but there is absolutely no room for error built into a gearbox like this. Repairs on worm gear sets with this mixture of metal are usually more costly and more time consuming than with a brass/steel worm equipment set. This is because the material transfer associated with failure makes both worm and the wheel unusable in the rebuild.
Brass worm and brass worm wheel – This software is most likely found in moderate to light load circumstances because the brass can only just keep up to a lower quantity of load. Lubricant selection upon this metal mixture is flexible because of the lighter load, but one must still consider the additive limitations regarding EP due to the yellow metal.
Plastic on metal, on plastic, and other comparable combinations – That is typically within relatively light load applications, such as robotics and auto components. The lubricant selection depends on the plastic in use, because many plastic varieties respond to the hydrocarbons in regular lubricant, and thus will require silicon-based or other non-reactive lubricants.
Although a worm gear will always have a few complications compared to a typical gear set, it can certainly be a highly effective and reliable device. With a little attention to setup and lubricant selection, worm gears can offer reliable service as well as any other kind of gear set.
A worm drive is one simple worm gear set system in which a worm meshes with a worm gear. Even it is simple, there are two essential components: worm and worm gear. (They are also known as the worm and worm wheel) The worm and worm wheel is important motion control component providing large acceleration reductions. It can decrease the rotational swiftness or increase the torque output. The worm drive motion advantage is they can transfer movement in right angle. It also comes with an interesting house: the worm or worm shaft can simply turn the gear, but the gear can not convert the worm. This worm drive self-locking feature allow worm gear includes a brake function in conveyor systems or lifting systems.
An Intro to Worm Gearbox
The most important applications of worm gears is used in worm gear box. A worm gearbox is called a worm reduction gearbox, worm gear reducer or a worm drive gearbox. It contains worm gears, shafts, bearings, and box frames.
The worm gear, shafts, bearings load are supported by the package shell. So, the gearbox housing will need to have sufficient hardness. Otherwise, it will result in lower transmission quality. As the worm gearbox comes with a durable, tranny ratio, small size, self-locking capacity, and simple structure, it is often used across a wide range of industries: Rotary desk or turntable, material dosing systems, auto feed machinery, stacking machine, belt conveyors, farm selecting lorries and more automation market.
How to Select High Efficient Worm Gearbox?
The worm gear manufacturing process is also relatively simple. However, there exists a low transmission efficiency problem if you don’t understand the how to select the worm gearbox. 3 basic indicate choose high worm gear efficiency that you ought to know:
1) Helix angle. The worm equipment drive efficiency mostly depend on the helix angle of the worm. Usually, multiple thread worms and gears is definitely more efficient than solitary thread worms. Proper thread worms can increase performance.
2) Lubrication. To choose a brand lubricating essential oil can be an essential factor to boost worm gearbox efficiency. As the proper lubrication can reduce worm equipment action friction and high temperature.
3) Material selection and Gear Manufacturing Technology. For worm shaft, the material should be hardened metal. The worm gear materials should be aluminium bronze. By reducing the worm equipment hardness, the friction on the worm teeth is decreased. In worm production, to use the specialized machine for gear slicing and tooth grinding of worms can also increase worm gearbox effectiveness.
From a huge transmission gearbox power to an even small worm gearbox load, you can choose one from an array of worm reducer that precisely matches your application requirements.
Worm Gear Box Assembly：
1) You can complete the installation in six various ways.
2) The installation should be solid and reliable.
3) Be sure to verify the connection between the motor and the worm equipment reducer.
4) You must use flexible cables and wiring for a manual installation.
By using the most advanced science and drive technology, we have developed several unique “square container” designed from high-quality aluminium die casting with a lovely appearance. The modular worm gearbox design series: worm drive gearbox, parallel shaft gearbox, bevel helical gearbox, spiral bevel gearbox, coaxial gearbox, correct angle gearbox. An NMRV series gearbox is usually a standard worm gearbox with a bronze worm equipment and a worm. Our Helical gearbox product line comprises of four universal series (R/S/K/F) and a step-less acceleration variation UDL series. Their structure and function act like an NMRV worm gearbox.
Worm gears are constructed of a worm and a gear (sometimes known as a worm wheel), with non-parallel, nonintersecting shafts oriented 90 degrees to each other. The worm is certainly analogous to a screw with a V-type thread, and the apparatus is usually analogous to a spur equipment. The worm is typically the generating component, with the worm’s thread advancing one’s teeth of the gear.
Like a ball screw, the worm in a worm gear may have an individual start or multiple starts – meaning that there are multiple threads, or helicies, on the worm. For a single-start worm, each complete turn (360 degrees) of the worm increases the gear by one tooth. Therefore a gear with 24 teeth will provide a gear reduced amount of 24:1. For a multi-start worm, the gear reduction equals the number of teeth on the gear, divided by the amount of begins on the worm. (That is not the same as almost every other types of gears, where the gear reduction is definitely a function of the diameters of both components.)
The worm in a worm gear assembly can have one start (thread) or multiple starts.
Image credit: Kohara Gear Market Company, Ltd.
The meshing of the worm and the gear is an assortment of sliding and rolling actions, but sliding contact dominates at high reduction ratios. This sliding actions causes friction and high temperature, which limits the performance of worm gears to 30 to 50 percent. In order to minimize friction (and for that reason, warmth), the worm and gear are constructed with dissimilar metals – for instance, the worm may be produced of hardened metal and the gear made of bronze or aluminum.
Although the sliding contact decreases efficiency, it provides extremely quiet operation. (The utilization of dissimilar metals for the worm and gear also plays a part in quiet operation.) This makes worm gears suitable for use where sound should be minimized, such as in elevators. Furthermore, the utilization of a softer materials for the gear means that it could absorb shock loads, like those skilled in large equipment or crushing machines.
The primary advantage of worm gears is their ability to provide high reduction ratios and correspondingly high torque multiplication. They may also be used as velocity reducers in low- to medium-rate applications. And, because their decrease ratio is based on the number of gear teeth alone, they are more compact than other styles of gears. Like fine-pitch business lead screws, worm gears are typically self-locking, which makes them well suited for hoisting and lifting applications.
A worm gear reducer is one type of reduction gear package which includes a worm pinion input, an output worm equipment, and includes a right angle result orientation. This type of reduction gear container is normally used to have a rated motor velocity and create a low speed result with higher torque value based on the decrease ratio. They often times can resolve space-saving problems because the worm equipment reducer is one of the sleekest reduction gearboxes available due to the little diameter of its output gear.
worm gear reducerWorm gear reducers are also a favorite type of speed reducer because they offer the greatest speed decrease in the tiniest package. With a higher ratio of speed decrease and high torque output multiplier, it’s unsurprising that many power transmission systems utilize a worm gear reducer. Some of the most typical applications for worm gears can be found in tuning instruments, medical assessment equipment, elevators, security gates, and conveyor belts.
Torque Transmission offers two sizes of worm gear reducer, the SW-1 and the SW-5 and both can be found in a variety of ratios. The SW-1 ratios include 3.5:1 to 60:1 and the SW-5 ratios include 5:1 to 100:1. Both of these options are manufactured with durable compression-molded glass-fill polyester housings for a durable, long lasting, light-weight speed reducer that’s also compact, noncorrosive, and nonmetallic.
Our worm gear reducers offer an option of a solid or hollow result shaft and show an adjustable mounting position. Both SW-1 and the SW-5, however, can endure shock loading better than other reduction gearbox styles, making them well suited for demanding applications.
Rugged compression-molded glass-fill up polyester housing
Light weight and compact
Range of ratios
SW-1, 3.5:1 to 60:1
SW-5, 5:1 to 100:1
Solid or Hollow output shaft
Adjustable mounting position
Low friction coefficient on the gearing for high efficiency.
Powered by long-long lasting worm gears.
Minimum speed fluctuation with low noise and low vibration.
Lightweight and compact relative to its high load capacity.
Compact design is one of the key phrases of the standard gearboxes of the BJ-Series. Further optimisation may be accomplished by using adapted gearboxes or particular gearboxes.
Our worm gearboxes and actuators are extremely quiet. This is due to the very smooth running of the worm gear combined with the use of cast iron and high precision on component manufacturing and assembly. Regarding the our precision gearboxes, we take extra care of any sound that can be interpreted as a murmur from the apparatus. So the general noise level of our gearbox is definitely reduced to a complete minimum.
On the worm gearbox the input shaft and output shaft are perpendicular to each other. This often proves to be a decisive advantage producing the incorporation of the gearbox considerably simpler and smaller sized.The worm gearbox can be an angle gear. This is often an edge for incorporation into constructions.
Strong bearings in solid housing
The output shaft of the BJ worm gearbox is quite firmly embedded in the gear house and is perfect for direct suspension for wheels, movable arms and other parts rather than having to create a separate suspension.
For larger gear ratios, BJ-Gear’s worm gearboxes provides a self-locking effect, which in many circumstances can be utilized as brake or as extra protection. Also spindle gearboxes with a trapezoidal spindle are self-locking, making them ideal for an array of solutions.
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