Polymer gears are characterized by their self-lubricating, low-cost, low-density,The advantages of high resilience and internal damping characteristics are increasingly valued,Its application fields are gradually shifting from the motion transmission fields such as toys, instruments, printers, etc. to the power transmission fields such as vehicle steering systems, engine balance shafts, etc.The expansion of the transmission field presents a trend of replacing steel with plastic. After long-term research,During the process, metal gears have formed a relatively complete evaluation system for the load-bearing capacity of tooth surfaces.However, polymer gears have certain limitations due to their material properties and metalSignificant differences exist in failure modes, fatigue life, and tooth surface load-bearing capacity, such as the elastic modulus of polymer gears with different materialsThe difference is relatively large, and the evaluation of contact fatigue strength limit often differs from the actual situation.The load-bearing capacity of the tooth surface is not consistent, so the load-bearing capacity of the metal gear tooth surfaceThe evaluation method cannot directly guide the evaluation of the load-bearing capacity of polymer gear tooth surfaces.Therefore, it is necessary to explore the evaluation method of the load-bearing capacity of polymer gear tooth surfaces.It is a pressing task for the current research and engineering application of polymer gears.Researchers have conducted a large number of polymer gear testsThe research found that the load-bearing capacity of the tooth surface of different material polymer gearsThere are significant differences between the failure modes, and the load-bearing capacity of the tooth surface is affected byExternal service conditions such as lubrication status and operating temperature have significant effects.]Tested 1.25 mm module machining under dry contactThe load limit of POM and PA6 gears, the results show that POM gearsThe ultimate load at fatigue fracture is 122% higher than that of PA6 gears,The deformation of PA6 gears is 140% greater than that of POM gears. Comparing POM and PK under oil lubrication at an output torque of 40 NโmFailure mode and durability life of (polyketone) gears, and discovery of POM teethContact fatigue failure of the wheel and PK gear, POM under high loadThe service life of gears is 70% higher than that of PK gears, but both areThere is no significant difference in service life. Hriberลกek et al. [8] conductedDurability test of POM/PA gear combination, compared to ordinary polyamide gearsCompared to steel gears, glass fiber reinforced polyamide gearsExhibits better durability under higher loads. Senthilvelan[9] analyzed injection molding of unreinforced PA6 andThe mechanical properties of 20% short glass fiber reinforced PA6 spur gears, resultsThe performance of glass fiber reinforced PA6 gears is superior to that of unreinforced onesPA6 gear. Researchers are studying the effects of different material types on polymerWhile the service performance of gears is affected, attention is gradually being paid to polymersThe influence of gear lubrication method.
The main lubrication methods for polymer gears in engineering applications are dry frictionWiping, grease lubrication and oil lubrication. Polymer teeth in the early motion transmission fieldThe wheels are mostly in dry friction or grease lubrication state.Wear behavior of dragon and glass fiber reinforced nylon gear pairs under dry contact,It was found that the wear rate of glass fiber reinforced nylon gears was lower than that of nylon gears.The durability test results of polymer gears indicate thatThe wear of polymer gears is not only related to torque, but also to speedClosely, the wear of gears increases gradually with the increase of speed, while the wear of glass fiberStrengthening improves the strength and modulus of PA gears at room temperature and high temperatures,Therefore, the wear resistance is improved. With the increasing load capacity of the polymer gear tooth surface,Increase the heat transfer efficiency of polymer gears under dry contact, and add materialsThe small thermal conductivity of the gear itself and the large amount of heat accumulated on the tooth surface during the meshing processThe risk of thermal failure is high, which hinders the use of polymer gears in high-speed and heavy-duty applications.For solving this problem, proper use of lubricants canEffectively reduce gear tooth surface friction, reduce meshing temperature and surface energy,Optimizing the service conditions of plastic gears and improving the load-bearing capacity of their tooth surfaces have beneficially promoted their potential applications in the field of power transmission.The country has carried out a large number of oil-lubricated polymer teethDuring the wheel durability test, it was found that the polymer gears under oil lubrication all suffered fromFatigue failure is mainly manifested as pitting corrosion on the tooth surface and fatigue fracture of the tooth root.Based on the gear fatigue tester, dry contact/oilThe load-bearing capacity test of the POM gear tooth surface was lubricated and found to be dry contactThe failure mode of the lower POM gear is excessive wear and melting, oil lubricationThe failure mode of the lower gear is pitting corrosion on the tooth surface, and the temperature of the lower gear tooth under oil lubrication iscompared to the ambient temperature, confirming that oil lubrication can significantlyreduce the temperature of POM gears and improve the load-bearing capacity of tooth surfaces. Through gear durability tests, it was also found that compared to dry contact conditions,Regardless of the type of polymer gear material, oil lubrication can significantly reduceFriction between gear pairs, which increases the load-bearing capacity of the gear tooth surface and leads to failureThe form is more stable.
Based on the experimental results of a large number of polymer gears, the use ofThe equivalent load is used to evaluate the load-bearing capacity of the tooth surface of the polymer gear.The concept of ‘surface energy’ was first applied in metal bearings as a theoretical basis for bearings.with calculated loads for bearing selection and design. However, polymer gearsThe elastic modulus of the material varies greatly depending on the polymer material, andThe temperature change of the polymer gear tooth body also affects the elastic modulus of the gearIn the practical application of polymer gears, the temperature of the gear tooth bodyIt varies depending on the operating temperature. Therefore, the equivalentWhen evaluating the load-bearing capacity of the tooth surface of a polymer gear, it is necessary to consider the influence of polymer properties such as viscosity,The elastic modulus of polymer gears varies with the polymer material and the actual application of the gear.The influence of temperature change of the tooth body.In practical application environments, the geometric structure and ringThe ambient temperature is not constant, and the polymer gear changes with the working conditions.Change, the geometric structure of gears and the elastic modulus of gears compared to metal teethThe wheel is more obvious, eliminating the geometric structure and elastic modulus of the polymer gearThe influence of the amount on the equivalent load of polymer gears, which is proposed in this paper, is labeled asThe concept of gear pair, which is the equivalent of the structural dimensions of polymer gearsThe load is converted to the equivalent load of the nominal gear pair, and then aggregatedComparative evaluation of the load-bearing capacity of the tooth surface of the gear.
Polymer gear teeth based on nominal gear equivalent loadThe applicability of the evaluation method for surface bearing capacity, further combined with other modelsThe contact fatigue test data of POM and PEEK gears are compareddifferent lubrication methods andUnder the same polymer material, the higher the reliability, the higher the gear contact fatigue strengthThe smaller the limit gap, the higher the reliability of the POM gear contactReduced fatigue S-N curve to extend gear life caused by different lubrication methodsThe change is different, so when calculating the equivalent load of polymer gearsThe contact fatigue strength limit at 50% reliability should be used. Figure 11 showsPOM and PEEK gear contact fatigue S-N curve at 50% reliabilityDue to different moduli, POM and PEO have different tensile strength under the same material and lubrication method.There are differences in the contact fatigue S-N curves of PEEK gears, but the differenceDifferent gear materials and lubrication methods do not affect the teeth of different polymer gears.When the fatigue life of the gear does not exceed 2ร107.The S-N curve of PEEK gears is always above that of POM gears.At the same fatigue life, PEEK gears can withstand higher tooth loadsSurface contact stress, indicating the tooth surface of PEEK gear under oil lubricationThe carrying capacity is higher than that of POM gears. The figure also compares POM gearsThe fatigue performance of the wheel under oil lubrication and grease lubrication,Under contact stress, POM gears with oil lubrication have higher fatigue lifeThe oil lubrication condition reduces the friction between gear pairs and stabilizes the teethThe running temperature of the tooth body of the wheel pair, thus improving the service life of the gearand the load-bearing capacity of the tooth surface.
For polymer gear materials, service environment, working conditions and loads, etc.It is difficult to determine the influence of multiple factors on the failure mode and load-carrying capacity of gears.For the problem of evaluating system reliability, the polymer gear is proposed to be used.The equivalent load ๐๐ถ method is used to evaluate the load-bearing capacity of gear tooth surfaces.Includes POM and PEEK materials, oil and grease lubrication methodsThe durability test of gears under the formula identified the failure modes of polymer gears.The high-load-bearing polyamide composite material, which includes tooth profile accuracy, tooth surface roughness, fatigue life, strength limit, failure diagram, and other aspects, is built.The basic database of composite gears. The main conclusions are as follows:1. Proposed a polymer gear based on the nominal gear equivalent loadThe evaluation method of tooth surface load-bearing capacity can realize different polymer materialsPolymer gear tooth surface load bearing capacity under the influence of multiple factors such as gear type, tooth profile, tooth profile shape, and lubrication methodThrough the comparison of the durability of 133 sets of polymer gears,It is found that the nominal gear equivalent of a typical polymer gear under oil lubricationThe range of load ๐๐ถ is 1.64~3.26;2. Based on the concept of equivalent load of gears proposed, the oil lubrication was comparedthe load capacity of the tooth surface of POM and PA66 gears under sliding and grease lubrication,The ๐๐ถ values of POM gears and PA66 gears under grease lubrication are 1.64 and 1.65, respectively.and 1.86, respectively, and the values of ๐๐ถ under oil lubrication are 2.15 and 2.21, indicating that oilThe load-bearing capacity of lubricated polymer gear tooth surface is higher than that of grease lubrication;3. The wear of POM, PA66 and PEEK gears under normal temperature oil lubricationThe nominal gear equivalent loads ๐๐ถ are 2.15, 2.21, and 2.82, respectively.The ๐๐ถ of PEEK gears is about 31% higher than that of POM and PA66 gears, respectivelyand 27%, indicating that PEEK gears have higherLoad bearing capacity of tooth surface.