- All
- Product Name
- Product Keyword
- Product Model
- Product Summary
- Product Description
- Multi Field Search
Language
Views: 222 Author: Ella Publish Time: 2025-03-24 Origin: Site
Content Menu
● Understanding Worm Gear Reducers
● The Importance of Preloading
>> 5. Elastic Preloading Device
>> Lubrication
>> Overheating
>> Variable Gear Preload for Virtual Play Reduction
● Applications of Worm Gear Reducers
● FAQ
>> 1. What is the main benefit of preloading a worm gear reducer?
>> 2. What are the common methods for preloading a worm gear reducer?
>> 3. How does lubrication affect the preload of a worm gear reducer?
>> 4. What should I do if my worm gear reducer is overheating?
>> 5. What materials are typically used for worms and worm wheels?
Worm gear reducers are essential components in various mechanical systems, offering efficient speed reduction and high torque transmission. Preloading a worm gear reducer is a technique used to minimize backlash, enhance precision, and improve the overall performance and lifespan of the gear system. This article provides a comprehensive guide on preloading a worm gear reducer, covering the necessary steps, considerations, and troubleshooting tips.
A worm gear reducer consists of a worm (a screw-like gear) that meshes with a worm wheel (a toothed wheel). This configuration allows for significant speed reduction in a compact space. Unlike other gear types, worm gears have sliding contact, resulting in low vibration and noise. They are commonly used in applications requiring high reduction ratios, such as industrial machinery, automotive systems, and robotics.
There are two main types of worm gears:
- Drum-shaped type (Troi drive worm): Achieves high transmission capacity and compact equipment. The drum-shaped troidal worm gear transmits power across its entire surface, providing high transmission capacity and functionality. This type is ideal for designing compact equipment. The gear teeth mesh in a unique way to achieve virtually no rotation variation.
- Cylindrical type (cylindrical worm): Optimizes capacity, efficiency, and cost.
Cone Drive's double-enveloping technology has the worm 'hugging' the gear, creating greater surface contact, higher load capacity, lower contact stress and greater shock capacity[3]. This allows for a smaller worm drive gearbox to save space or increase the motor to get more power[3].
Preloading involves applying a controlled load or pressure to the gear components to eliminate backlash and ensure continuous contact between the worm and worm wheel. Backlash is the clearance or play between mating gear teeth, which can cause inaccuracies, vibrations, and increased wear. Preloading helps in several ways:
- Enhanced Precision and Accuracy: By minimizing backlash, preloading ensures that the gear system responds accurately to changes in direction or load.
- Reduced Wear and Extended Lifespan: Continuous contact reduces impact loading and wear on gear teeth, extending the lifespan of the worm gear reducer.
- Improved System Stability and Control: Preloading enhances the stability of the system, providing smoother and more predictable operation.
Purpose: To control the axial position of the worm and worm wheel to achieve proper meshing and preload.
1. Disassembly: Begin by disassembling the worm gear reducer, following the manufacturer's instructions. Remove the gear carrier and gear shaft assembly from the housing. Keep track of the number of shims needed under the carrier for reference during reassembly.
2. Inspection: Inspect the shims for wear or damage. Replace them if necessary. New shims will ensure accurate adjustment and preload.
3. Adjustment: Place shims of varying thicknesses between the gear carrier and the housing to adjust the axial position of the worm wheel. The goal is to minimize backlash while ensuring smooth rotation.
4. Measurement: Use a dial indicator to measure the backlash. Mount the indicator on a stable base and position the probe against a tooth on the worm wheel. Apply a slight force to the worm wheel and measure the total travel of the indicator.
5. Reassembly: Reassemble the worm gear reducer, ensuring that all components are properly aligned and tightened according to the manufacturer's specifications.
6. Testing: Rotate the worm shaft and check for smooth, consistent movement. There should be minimal backlash and no binding.
7. Final Adjustment: Make final adjustments to the shims as needed to achieve the desired preload and backlash.
Purpose: To apply a constant axial force on the worm shaft using springs to maintain continuous contact between the worm and worm wheel.
Components:
- Belleville springs or compression springs
- Thrust bearings
- Adjusting nuts or collars
Procedure:
1. Installation: Install thrust bearings on either side of the worm gear to handle the axial forces.
2. Spring Placement: Place Belleville springs or compression springs against the thrust bearings. Belleville springs are preferred due to their ability to provide a consistent force over a range of compression.
3. Adjustment: Use adjusting nuts or collars to compress the springs, applying a controlled axial force on the worm shaft.
4. Testing: Rotate the worm shaft to ensure smooth operation. Adjust the spring compression until the desired preload is achieved.
Purpose: To eliminate backlash by using two worms to engage the worm wheel from opposite sides, effectively preloading the system. This method is more complex but offers precise control and stability.
Components:
- Two worms
- Worm wheel
- Adjustment mechanisms
Procedure:
1. Setup: Mount the two worms so that they engage the worm wheel from opposite sides.
2. Adjustment: Adjust the axial position of each worm to eliminate backlash. This can be achieved using threaded adjusters or shims.
3. Synchronization: Ensure that the worms are synchronized to provide smooth and consistent movement.
4. Testing: Rotate the worms and check for minimal backlash and smooth operation.
Purpose: This method involves using a worm gear that is split along its axis, with a mechanism to adjust the relative position of the two halves. This adjustment allows for precise control over backlash and preload.
Components:
- Split worm gear
- Adjustment screws or mechanism
- Locking mechanism
Procedure:
1. Installation: Install the split worm gear into the reducer housing.
2. Adjustment: Use the adjustment screws or mechanism to move the two halves of the worm gear relative to each other. This will tighten the engagement with the worm wheel, reducing backlash.
3. Locking: Once the desired preload is achieved, use the locking mechanism to secure the position of the worm gear halves.
4. Testing: Rotate the worm shaft and check for minimal backlash and smooth operation. Make any necessary fine adjustments and re-lock the mechanism.
Purpose: To utilize an elastic preloading device such as a spring to apply a pre-tightening force to eliminate backlash in a worm gear and worm pair.
Components:
- Elastic preloading device (spring, hydraulic device, or air pressure device)
- Adjusting nut
- Spring positioning sleeves
Procedure:
1. Installation: Coaxially install the main force worm and the resistance toroidal worm.
2. Adjustment: Adjust the resistance worm in the axial direction and apply pre-tightening force through the elastic preloading device. Use the adjusting nut to adjust and preload the resistance worm in the axial direction.
3. Testing: Check for stable, efficient, and low-noise transmission.
The materials used for the worm and worm wheel significantly affect the performance and durability of the gear system. Worms are typically made of hardened steel, while worm wheels are often made of bronze or other non-ferrous alloys. The combination of a hard worm and a softer worm wheel provides good wear resistance and low friction. High strength, high hardness, and high wear resistance materials should be selected, such as stainless steel, alloy steel, or cast iron[4]. Surface treatment processes such as carburizing quenching and nitride can be adopted to improve the surface hardness and wear resistance, and enhance the bearing capacity of the reducer[4].
Proper lubrication is crucial for reducing friction and wear in worm gear reducers. Use high-quality gear oil that is specifically designed for worm gear applications. Ensure that the lubricant is compatible with the gear materials and operating conditions. Lubricants with good lubrication performance, oxidation resistance, wear resistance, and rust resistance shall be selected according to the working conditions and requirements[4]. The lubricating oil commonly used for worm gear reducer includes gear oil and synthetic oil[4]. When selecting lubricating oil, viscosity is too high to increase friction resistance and reduce transmission efficiency; viscosity is too low to reduce the bearing capacity and aggravate wear[4]. The lubricating oil with appropriate viscosity grade shall be selected according to the working temperature and load condition, etc[4]. For applications with high carrying capacity requirements or high rotation speed, forced lubrication can be considered to pump the lubricating oil to each component[4].
The operating conditions, such as speed, load, and temperature, can affect the preload and performance of the worm gear reducer. High loads and temperatures can cause the lubricant to break down and increase wear. Monitor the operating conditions and adjust the preload and lubrication as needed.
The quality of assembly plays a critical role in the performance of the worm gear reducer. Ensure that all components are properly aligned and tightened according to the manufacturer's specifications. Improper assembly can lead to premature wear and failure.
Reasonable selection of module and worm diameter coefficient is important[4]. Increasing the module can improve the load-bearing capacity, but it will also increase the size and weight of the reducer[4]. The appropriate module needs to be selected based on the load requirements and space constraints of the specific application[4]. For high load applications, it is recommended to select a larger module[4]. The worm diameter coefficient affects the performance of the reducer[4]. The larger the coefficient, the greater the worm stiffness and the higher the load-bearing capacity, but the helix angle will decrease, reducing the transmission efficiency[4]. It is necessary to weigh the load-bearing capacity and transmission efficiency to select the appropriate worm diameter coefficient[4].
Consider heat dissipation measures in the design, such as adding a heat sink or using a fan, to reduce the working temperature and prevent overheating from leading to the decrease of the bearing capacity.
Use a frequency converter to control the motor speed, avoid instantaneous overload and improve the service life of the reducer[4].
Causes:
- Worn or damaged gear teeth
- Improper preload adjustment
- Loose components
Solutions:
- Replace worn or damaged gears.
- Readjust the preload according to the manufacturer's specifications.
- Tighten any loose components.
Causes:
- Insufficient lubrication
- Excessive preload
- High operating loads
Solutions:
- Ensure proper lubrication with the correct type of gear oil.
- Reduce the preload to the recommended level.
- Reduce the operating loads or improve cooling.
Causes:
- Excessive backlash
- Misalignment
- Worn bearings
Solutions:
- Adjust the preload to minimize backlash.
- Realign the gear components.
- Replace worn bearings.
- A variable pretension mechanism can reduce virtual play, leading to a reduction in position indeterminacy. Gears need a small amount of play or backlash to prevent the transmission from seizing by uncontrollable teeth forces. However, in precision engineering, this play is often unwanted because it creates a position indeterminacy. A commonly used solution to this problem is to pretension the gears to remove this backlash. In worm gear transmissions where the sliding component is large, friction force, together with the stiffness determine the virtual backlash.
- One of the more sophisticated ways to control backlash is called gear train preloading[1]. A torsion spring or weight on the last driven gear in a system loads one side of the meshing teeth to eliminate tooth clearance[1]. The spring or weight travel, however, limits the amount of rotation of the last gear[1]. For unlimited rotation, an auxiliary motor can provide the load rather than a spring or weight[1]. This method is especially useful for gear trains with many stages, where backlash is cumulative[1]. Spring-loaded versions work best in low-torque, uni-directional drives[1].
- A particularly effective solution for miniature spur gear systems consists of dual-path gear trains with identical gears mounted in parallel. The gear trains are wound against each other (rotated in opposite directions) to force mating teeth together. Then a motor shaft with pinion gear is inserted into the gearhead to maintain a preload on the teeth. It acts like a spring load on the gear train even though there is no spring. This method provides zero backlash operation without specially designed gears. However, it doubles the number of gears needed in a system and involves additional assembly time.
- Tapered helical and spur gears provide another approach[1]. These gears have teeth cut at a slight angle to provide a tapered tooth form[1]. An assembler adjusts the tooth clearance by moving the gears relative to each other in an axial direction[1].
A worm gear is used in Column type Electric Power Steering (C-EPS) systems and an Anti-Rattle Spring (ARS) is employed in C-EPS systems in order to prevent rattling when the vehicle goes on a bumpy road. This ARS plays a role of preventing rattling by applying preload to one end of the worm shaft but it also generates undesirable friction by causing misalignment of the worm shaft.
- Worm gear reducers are used widely in a variety of industrial machinery. This includes conveyors[2], winches, machining equipment, amusement park equipment, stage equipment, multilevel parking garages, automatic assembly equipment, food product manufacturing equipment, medical equipment, and traveling cranes. Worm speed reducers are also utilized in rotary stockers, leveraging their quiet operation, accurate positioning, self-locking capabilities, and optional dual input shafts for manual drives during power outages. Other applications include gear reducers, stairlifts, elevators, conveyor belts[2], gate controls, and guitars.
- Worm gear reducers are commonly used in conveyor systems[2], hoists, and lifts, where high torque and load-holding capabilities are essential[2]. The compact design of worm gearboxes makes them ideal for conditions of food and beverage processing, allowing for high torque with a small footprint. Worm gearboxes' self locking features are perfect for security gates and automated doors, providing the safety of a locked position without requiring constant power. Worm gearboxes are favored for their compact size, quiet operation, and reliability in high-torque, low-speed applications within packaging machinery. They are also widely used in environmental protection equipment, such as sewage treatment equipment and garbage treatment equipment. They are used in aerospace, marine, energy, and other fields, such as marine drilling equipment and ship propulsion systems. They are found in metallurgical mining machinery in the mine of the ball mill, crusher, coal mill and other equipment. Precision worm gear reducers are used in the new energy field of solar power generation and wind power generation, for solar energy, wind power generator energy tracking systems and other equipment. Worm gear reducers are used in construction machinery such as elevators, mixers[2], conveyor belts and other equipment.
- Worm gear reducers can achieve extremely large reduction ratios, thereby outputting larger torques to meet the needs of heavy-duty working conditions[2].
- The CYWF series worm gear reducer is a mechanical transmission device designed for industrial applications that require high load and high torque output. They are widely used in various heavy machinery and equipment, such as boring machines, rolling mills, die-casting machines, cranes, conveyor belts, crushers, mixers and other equipment that require high reduction ratios and high load-bearing capacity in the fields of metallurgy, mining, chemical industry, and construction.
Preloading a worm gear reducer is a critical step in optimizing its performance, reducing wear, and extending its lifespan. By carefully adjusting the preload using shims, springs, dual worm configurations, or adjustable split worm designs, you can minimize backlash, enhance precision, and improve the overall reliability of the gear system. Regular maintenance, proper lubrication, and attention to operating conditions are essential for maintaining the desired preload and ensuring long-term performance.
Preloading minimizes backlash, which enhances precision, reduces wear, and improves system stability.
Common methods include shim adjustment, spring preloading, dual worm configuration, adjustable split worm designs, and elastic preloading devices.
Proper lubrication reduces friction and wear, helping to maintain the desired preload and preventing overheating.
Check for insufficient lubrication, excessive preload, or high operating loads. Ensure proper lubrication, reduce the preload, or improve cooling as needed.
Worms are typically made of hardened steel, while worm wheels are often made of bronze or other non-ferrous alloys. High strength materials, such as stainless steel, alloy steel, or cast iron can also be used[4].
[1] https://www.machinedesign.com/mechanical-motion-systems/article/21831618/methods-to-minimize-gear-backlash
[2] https://www.jiegroup.com/news/industry-information/gear-motor-vs-worm-gear-reducer-a-complete-analysis-of-performance-differences-and-application-scenarios.html
[3] https://conedrive.com/double-enveloping-worm/
[4] https://www.tengkai1.com/info/practical-methods-to-improve-the-load-carrying-102148552.html
[5] https://www.machinedesign.com/motors-drives/article/21828631/worm-gears-remove-drive-backlash
[6] https://www.ever-power.net/are-there-any-innovative-technologies-or-advancements-in-worm-gearbox-design-in-616/
[7] https://redexusa.com/servo-reducers-control-backlash-in-composite-machinery-part-1/
[8] https://www.taiwan-drive.com/en-US/plist5-worm-gear-reducer
[9] https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=586597781c6c56413c1222e37b0d3ecd5ff7325d
[10] https://www.practicalmachinist.com/forum/threads/worm-gear-reducer-woes.81514/
[11] https://gearsolutions.com/features/a-decomposition-of-the-torsional-stiffness-of-a-worm-gearbox-into-individual-components/
[12] https://www.chunyeh.com.tw/gearbox-design-r-d.htm
[13] https://www.ever-power.net/how-to-increase-the-load-capacity-of-worm-gear-reducers/
[14] https://www.irjet.net/archives/V8/i5/IRJET-V8I5662.pdf
[15] https://blog.hzpt.com/what-are-the-innovations-in-worm-reducer-gearbox-design/
[16] https://hzpt.com/blog/how-do-worm-reducer-gearboxes-handle-backlash/
[17] https://asmedigitalcollection.asme.org/mechanicaldesign/article/134/5/054501/450539/Effects-of-Bearing-Preload-Oil-Volume-and
[18] https://www.zhygear.com/innovations-in-worm-gear-technology-advancements-and-trends/
[19] https://www.eng-tips.com/threads/worm-drive-backlash-quantification.67911/
[20] https://bauergmc.com/worm-gear-motors-design-challenges-and-their-solutions.html
