Worm gears are usually used when large rate reductions are needed. The decrease ratio is determined by the number of starts of the worm and number of tooth on the worm equipment. But worm gears possess sliding contact which is peaceful but will produce heat and have relatively low tranny efficiency.
For the materials for production, in general, worm is made of hard metal as the worm gear is made from relatively soft steel such as aluminum bronze. That is since the number of teeth on the worm gear is relatively high in comparison to worm using its number of starts being generally 1 to 4, by reducing the worm gear hardness, the friction on the worm the teeth is reduced. Another characteristic of worm manufacturing may be the need of specialized machine for gear trimming and tooth grinding of worms. The worm gear, however, may be made with the hobbing machine used for spur gears. But due to the different tooth shape, it is not possible to cut several gears at once by stacking the apparatus blanks as can be carried out with spur gears.
The applications for worm gears include gear boxes, fishing pole reels, guitar string tuning pegs, and in which a delicate velocity adjustment by utilizing a huge speed reduction is needed. When you can rotate the worm gear by worm, it is usually not possible to rotate worm utilizing the worm gear. That is called the self locking feature. The self locking feature cannot always be assured and another method is recommended for accurate positive reverse prevention.
Also there is duplex worm gear type. When working with these, you’ll be able to adjust backlash, as when the teeth put on necessitates backlash adjustment, without needing a alter in the center distance. There aren’t too many manufacturers who can generate this type of worm.
The worm gear is additionally called worm wheel in China.
A worm equipment 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 gear, and a version of one of the six simple machines. Basically, a worm equipment is a screw butted against what looks like a typical spur gear with slightly angled and curved teeth.
It changes the rotational movement by 90 degrees, and the plane of motion also changes due to the placement of the worm on the worm wheel (or simply “the wheel”). They are typically comprised of a metal worm and a brass wheel.
Worm Gear
Figure 1. Worm gear. Most worms (but not all) are at the bottom.
How Worm Gears Work
An electric electric motor 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 pushed against the strain.
Worm Gear Uses
There are a few reasons why you might choose a worm gear over a standard gear.
The first one may be the high reduction ratio. A worm gear can have a massive reduction ratio with little effort – all one should do is usually add circumference to the wheel. Thus you can use it to either significantly increase torque or greatly reduce speed. It’ll typically take multiple reductions of a typical gearset to attain the same reduction degree of a single worm gear – meaning users of worm gears possess fewer shifting parts and fewer areas for failure.
A second reason to use a worm gear is the inability to reverse the direction of power. Due to the friction between the worm and the wheel, it is virtually extremely hard for a wheel with force applied to it to begin the worm moving.
On a standard gear, the input and output could be switched independently once enough force is used. This necessitates adding a backstop to a typical gearbox, further increasing the complication of the gear set.
Why Not to Use Worm Gears
There is one especially glaring reason why one would not choose a worm gear more than a typical gear: lubrication. The motion between the worm and the wheel equipment faces is entirely sliding. There is no rolling element of the tooth contact or interaction. This makes them fairly difficult to lubricate.
The lubricants required are usually high viscosity (ISO 320 and better) and therefore are hard to filter, and the lubricants required are usually specialized in what they do, requiring a product to be on-site particularly for that type of equipment.
Worm Gear Lubrication
The main 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 huge amounts of reduction in a comparatively little bit of space for what is required if a typical helical equipment were used.
This spiral motion also causes a remarkably problematic condition to be the principal mode of power transfer. This is often called sliding friction or sliding wear.
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With an average gear set the energy is transferred at the peak load point on the tooth (known as the apex or pitchline), at least in a rolling wear condition. Sliding takes place on either side of the apex, however the velocity is relatively low.
With a worm gear, sliding motion may be the only transfer of power. As the worm slides across the tooth of the wheel, it slowly rubs off the lubricant film, until there is no lubricant film still left, and as a result, the worm rubs at the metal of the wheel in a boundary lubrication regime. When the worm surface leaves the wheel surface, it accumulates more lubricant, and begins the process once more on another revolution.
The rolling friction on an average gear tooth requires little in the form of lubricant film to complete the spaces and separate the two components. Because sliding happens on either part of the apparatus tooth apex, a somewhat higher viscosity of lubricant than is certainly strictly necessary for rolling wear is required to overcome that load. The sliding happens 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 certainly to possess a film thickness large enough never to have the whole tooth surface wiped off before that section of the worm has gone out of the load zone.
This scenario requires a special sort of lubricant. Not only will it should be a relatively high viscosity lubricant (and the bigger the load or temperature, the bigger the viscosity should be), it will need to have some way to help get over the sliding condition present.
Read The Right Way to Lubricate Worm Gears for more information on this topic.
Viscosity is the major factor in preventing the worm from touching the wheel in a worm gear set. As the load and size of gearing determines the required 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 selection of viscosity, you know it is problematic because it is most likely that none of the filters or pumps you possess on-site would be the appropriate size or rating to function properly.
Therefore, you’ll likely have to get a particular pump and filter for this type of unit. A lubricant that viscous takes a gradual operating pump to prevent the lubricant from activating the filter bypass. It will also require a huge surface area filter to permit the lubricant to flow through.
Lubricant Types to consider
One lubricant type commonly used with worm gears is mineral-based, compounded equipment oils. There are no additives that can be placed into a lubricant that can make it conquer sliding wear indefinitely, but the organic or synthetic fatty additive combination in compounded gear oils results in great lubricity, providing an extra measure of protection from metal-to-metal contact.
Another lubricant type commonly used in combination with worm gears is mineral-based, commercial extreme pressure (EP) equipment oils. There are some problems with this type of lubricant in case you are using a worm gear with a yellow metallic (brass) component. However, in case you have fairly low operating temperatures or no yellow metal present on the gear tooth areas, this lubricant is effective.
Polyalphaolefin (PAO) gear lubricants work well in worm equipment applications because they naturally have great lubricity properties. With a PAO equipment oil, it’s important to view the additive package, because these can have EP additives. A standard-duty antiwear (AW) fortified gear essential oil will typically become acceptable, but be sure the properties are compatible with most metals.
The writer recommends to closely watch the use metals in oil analysis testing to make sure that the AW bundle isn’t so reactive concerning trigger significant leaching from the brass. The effect should be far less than what would be seen with EP actually in a worst-case scenario for AW reactivity, nonetheless it can show up in metals assessment. If you need a lubricant that may handle higher- or lower-than-typical temperatures, a suitable PAO-based product is likely available.
Polyalkylene glycols (PAG), a fourth kind of lubricant, are becoming more prevalent. These lubricants have superb lubricity properties, and don’t contain the waxes that trigger low-temperature problems with many mineral lubricants, making them an excellent low-temperature choice. Caution should be taken when using PAG oils because they are not compatible with mineral oils, plus some seals and paints.
Metallurgy of Worm Gears
The most common worm gears are created with a brass wheel and a steel worm. This is because the brass wheel is normally easier to replace than the worm itself. The wheel is made out of brass because it was created to be sacrificial.
In the event that the two surfaces come into contact, the worm is marginally safe from wear since the wheel is softer, and therefore, the majority of the wear occurs on the wheel. Oil analysis reports on this kind of unit more often than not show some degree of copper and low levels of iron – as a result 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 usually high enough, the EP additive will activate. In normal metal gears, this activation produces 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 brief timeframe, you can get rid of a significant portion of the load surface of the wheel and trigger major damage.
Other Materials
Some of the less common materials found in worm gear models include:
Steel worm and metal worm wheel – This program does not have the EP problems of brass gearing, but there is no room for error included in a gearbox like this. Repairs on worm gear sets with this mixture of metal are typically more costly and additional time eating than with a brass/steel worm equipment set. This is because the material transfer connected with failure makes both the worm and the wheel unusable in the rebuild.
Brass worm and brass worm wheel – This application is most likely within moderate to light load situations because the brass can only keep up to a lower quantity of load. Lubricant selection on this metal combination is flexible due to the lighter load, but one must still consider the additive restrictions regarding EP due to the yellow metal.
Plastic on metal, upon plastic, and other comparable combinations – That is typically found in relatively light load applications, such as for example robotics and automotive components. The lubricant selection depends upon the plastic used, because many plastic varieties react to the hydrocarbons in regular lubricant, and therefore will require silicon-based or other non-reactive lubricants.
Although a worm gear will always have a couple of complications compared to a standard gear set, it can easily be an effective and reliable device. With a little attention to setup and lubricant selection, worm gears can provide reliable service as well as any other kind of gear set.
A worm drive is one particular worm gear set system when a worm meshes with a worm equipment. Even it is simple, there are two essential components: worm and worm gear. (Also, they are known as the worm and worm wheel) The worm and worm wheel is essential motion control element providing large quickness reductions. It can decrease the rotational velocity or boost the torque output. The worm drive motion advantage is they can transfer movement in right angle. It also comes with an interesting real estate: the worm or worm shaft can easily turn the gear, but the gear can not really convert the worm. This worm drive self-locking feature let the worm gear has a brake function in conveyor systems or lifting systems.
An Launch to Worm Gearbox
The most important applications of worm gears is utilized in worm gear box. A worm gearbox is named a worm reduction gearbox, worm equipment reducer or a worm drive gearbox. It includes worm gears, shafts, bearings, and box frames.
The worm equipment, shafts, bearings load are supported by the box shell. Therefore, the gearbox housing will need to have sufficient hardness. Or else, it will result in lower transmitting quality. As the worm gearbox comes with a durable, transmitting ratio, small size, self-locking capability, and simple structure, it is often used across a wide selection of industries: Rotary table or turntable, material dosing systems, auto feed machinery, stacking machine, belt conveyors, farm selecting lorries and more automation sector.
How to Select High Efficient Worm Gearbox?
The worm gear manufacturing process is also relatively simple. However, there exists a low transmission efficiency problem in the event that you don’t understand the how to select the worm gearbox. 3 basic point to choose high worm equipment efficiency that you ought to know:
1) Helix position. The worm gear drive efficiency mostly rely on the helix position of the worm. Usually, multiple thread worms and gears is usually more efficient than one thread worms. Proper thread worms can increase performance.
2) Lubrication. To choose a brand lubricating essential oil is an essential factor to boost worm gearbox efficiency. As the correct lubrication can reduce worm gear action friction and heat.
3) Materials selection and Gear Manufacturing Technology. For worm shaft, the material should be hardened metal. The worm gear material should be aluminium bronze. By reducing the worm gear hardness, the friction on the worm teeth is decreased. In worm production, to use the specialized machine for gear trimming and tooth grinding of worms can also increase worm gearbox efficiency.
From a huge transmission gearbox power to a straight small worm gearbox load, you can choose one from a wide range of worm reducer that precisely fits your application requirements.
Worm Gear Box Assembly：
1) You may complete the set up in six different ways.
2) The installation must be solid and reliable.
3) Be sure to check the connection between your engine and the worm equipment reducer.
4) You must make use of flexible cables and wiring for a manual installation.
With the help of the innovative science and drive technology, we’ve developed several unique “square container” designed from high-quality aluminium die casting with a beautiful appearance. The modular worm gearbox style series: worm drive gearbox, parallel shaft gearbox, bevel helical gearbox, spiral bevel gearbox, coaxial gearbox, right angle gearbox. An NMRV series gearbox can be a standard worm gearbox with a bronze worm gear and a worm. Our Helical gearbox products consists of four universal series (R/S/K/F) and a step-less swiftness variation UDL series. Their structure and function are similar to an NMRV worm gearbox.
Worm gears are constructed of a worm and a gear (sometimes referred to as a worm wheel), with non-parallel, nonintersecting shafts oriented 90 degrees to each other. The worm can be analogous to a screw with a V-type thread, and the gear is certainly analogous to a spur gear. The worm is typically the driving component, with the worm’s thread advancing the teeth of the gear.
Just 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 full turn (360 degrees) of the worm increases the gear by one tooth. So 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 apparatus, divided by the number of begins on the worm. (This is different from almost every other types of gears, where the gear reduction is a function of the diameters of the two components.)
The worm in a worm gear assembly can have one start (thread) or multiple starts.
Picture credit: Kohara Gear Market Company, Ltd.
The meshing of the worm and the gear is a mixture of sliding and rolling actions, but sliding contact dominates at high reduction ratios. This sliding actions causes friction and warmth, which limits the performance of worm gears to 30 to 50 percent. In order to minimize friction (and for that reason, high temperature), the worm and equipment are made of dissimilar metals – for example, the worm may be produced of hardened metal and the gear made of bronze or aluminum.
Although the sliding contact reduces efficiency, it provides extremely quiet operation. (The use 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 use of a softer materials for the gear implies that it can absorb shock loads, like those experienced in weighty equipment or crushing devices.
The primary benefit of worm gears is their ability to provide high reduction ratios and correspondingly high torque multiplication. They may also be utilized as acceleration reducers in low- to medium-quickness applications. And, because their reduction ratio is based on the amount of gear teeth only, they are more compact than other styles of gears. Like fine-pitch lead screws, worm gears are usually self-locking, making them well suited for hoisting and lifting applications.
A worm gear reducer is one kind of reduction gear package which consists of a worm pinion insight, an output worm gear, and features a right angle result orientation. This type of reduction gear package is generally used to take a rated motor quickness and produce a low speed result with higher torque worth based on the decrease ratio. They often times can solve space-saving problems since the worm gear reducer is among the sleekest decrease gearboxes available due to the small diameter of its result gear.
worm gear reducerWorm gear reducers are also a favorite type of speed reducer because they provide the greatest speed reduction in the smallest package. With a high ratio of speed decrease and high torque output multiplier, it’s unsurprising that many power transmission systems make use of a worm gear reducer. Some of the most typical applications for worm gears are available in tuning instruments, medical examining equipment, elevators, protection gates, and conveyor belts.
Torque Transmission provides 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 produced with durable compression-molded glass-fill polyester housings for a long lasting, long lasting, light-weight speed reducer that’s also compact, non-corrosive, and nonmetallic.
Features
Our worm equipment reducers offer an option of a solid or hollow result shaft and show an adjustable mounting position. Both SW-1 and the SW-5, nevertheless, can withstand shock loading better than other decrease gearbox styles, making them perfect for demanding applications.
Rugged compression-molded glass-fill up polyester housing
Light-weight and compact
Non corrosive
Non metallic
Range of ratios
SW-1, 3.5:1 to 60:1
SW-5, 5:1 to 100:1
Grease Lubrication
Solid or Hollow output shaft
Adjustable mounting position
Overview
Technical Info
Low friction coefficient on the gearing for high efficiency.
Powered by long-long lasting worm gears.
Minimal speed fluctuation with low noise and low vibration.
Lightweight and compact relative to its high load capacity.
Compact design
Compact design is among the key terms of the typical gearboxes of the BJ-Series. Further optimisation can be achieved through the use of adapted gearboxes or particular gearboxes.
Low noise
Our worm gearboxes and actuators are really quiet. This is due to the very smooth working of the worm gear combined with the use of cast iron and high precision on component manufacturing and assembly. In connection with our precision gearboxes, we take extra care of any sound which can be interpreted as a murmur from the gear. So the general noise level of our gearbox is definitely reduced to a complete minimum.
Angle gearboxes
On the worm gearbox the input shaft and output shaft are perpendicular to one another. This often proves to be a decisive advantage producing the incorporation of the gearbox considerably simpler and more compact.The worm gearbox can be an angle gear. This is often an advantage for incorporation into constructions.
Solid bearings in solid housing
The output shaft of the BJ worm gearbox is quite firmly embedded in the apparatus house and is ideal for immediate suspension for wheels, movable arms and other areas rather than having to build a separate suspension.
Self locking
For larger equipment ratios, BJ-Gear’s worm gearboxes provides a self-locking effect, which in many circumstances can be used as brake or as extra protection. Also spindle gearboxes with a trapezoidal spindle are self-locking, making them ideal for a wide selection of solutions.