丝杆间隙和相关故障

1、丝杆间隙和相关故障Published: 2010-2-1 11:53:28 source: Shanghai Lianheng Pml Precision Mechanism LtdMobile related shaft with manual pulse generator (hand pulse rate set at 1 x 100 gear, which changes every step motor with 0.1mm), observe the movement axis related indicators. When the accuracy of unidirectio

2、nal motion remains normal, as the forward motion of the starting point, each step of the hand pulse changes, the actual distance of the axis of the machine tool moves d=d1=d2=d3. =0.1mm, indicating that the motor runs well and the positioning accuracy is good. Change and return machine actual displa

3、cement, can be divided into four stages: the machine movement distance of D1 and d=0.1mm (the slope is greater than 1); the show was d=0.1mm D2 D3 (less than 1); the actual machine does not move, showing the reverse gap the standard; the machine tool movement distance with the hand vein (equal to th

4、e given value is equal to the slope of 1), restored to the normal movement of the machine.Most of the faults of ball screws are due to the decrease of the quality of movement, excessive reverse clearance, mechanical creep and poor lubrication. The following table shows the common faults of ball scre

5、ws and their diagnostic methods.Fault diagnosis of ball screw pairSerial numberFault phenomenonFailure causeRemoval method, the workpiece roughness value is highThe lubricating oil of the guide rail is not enough to cause the sliding board to crawlAdd lubricating oil to eliminate lubrication trouble

6、The ball screw has local scratch or abrasionReplace or repair screw rodsThe screw rod bearing is damaged and the movement is not smoothReplace damaged bearingsThe servo motor is not adjusted and the gain is too largeServo motor control system, the reverse error is big, the processing accuracy is uns

7、tableLoosening of taper sleeve of screw shaft couplingRe tighten and repeated the test indicatorThe tie plate of the screw rod is too tight or too looseRe - adjust or repair, not qualified by 0.03mm raceThe wire rod slide is too tight or too loose with the wedgeRe adjustment or repair, so that the c

8、ontact rate of more than 70%, with 0.03mm race failed to qualifiedThe ball screw is too tight or too looseAdjust the preload, check the axial movement value, so that the error is not greater than 0.015mmThe end of the nut of the ball screw is not perpendicular to the joint surface and is too looseRe

9、pair, adjustment, or pad handlingThe wire rod bearing is too tight or too looseRepair adjustmentBall screw manufacturing error or axial movementThe automatic compensation of the control system can eliminate the gap and measure and adjust the traverse of the screw rod with an instrumentThe lubricant

10、is inadequate or notAdjust to all rail surfaces are lubricating oilOther mechanical interferenceExclude interference partsball screw in operation torque is too largeTwo skateboard with pressure plate too tight or damageReadjust or repair the platen so that the 0.04mm race stopper is not qualifiedThe

11、 ball screw nut reverse device is damaged, the ball screw is clamped or the end of the shaft nut is too bigRepair or replace the screw rod and adjust carefullyWire rod grinding lossreplaceThe servo motor is connected with the ball screw shaft by different shaftsAdjust the coaxiality and fasten the c

12、onnecting seatOil-freeAdjust the oil circuitExcessive switch failure, resulting in mechanical failureCheck faults and eliminate themServo motor overheat alarmCheck faults and eliminate themscrew nut lubrication badIs the oil distributor split?Check quantitative oil separatorIs the tubing blocked?Cle

13、ar the dirt to smooth the tubingball screw pair noiseBall screw bearing gland pressure tightAdjust gland to press the bearingsBall screw lubrication badlyCheck the oil separator and the oil circuit so that the oil isadequateBall breakageChange ballThe motor and the screw shaft coupling are loosenedT

14、ighten the coupling lock screwsThe cause of gear noise and its solutionTraditionally, the two main factors that determine the performance of gear transmission are load capacity and fatigue life, which tend to ignore the driving noise and transmission accuracy. With ISO14000 and ISO18000 two standard

15、s have been promulgated, the importance of controlling factors of gear transmission noise is obvious, transmission error of industrial development and demand for high precision equipment requirements more stringent (gear backlash). Gear noise formation factors currently known,Generally from the desi

16、gn, manufacture, installation, use, maintenance and other aspects of analysis.Design reasons and Countermeasuresgear accuracy classIn the design of gear transmission system, the designers usually consider the economic factors, and determine the gear accuracy level as much as possible, but the accura

17、cy level is the mark of the noise level and the backlash of the gear. The American Gear Manufacturers Association used a large number of gear studies to determine that gears with higher accuracy would have less noise than low precision gears. Therefore, under theconditions permit, we should improve

18、the accuracy level of gear as much as possible to reduce gear noise and reduce transmission error.gear widthIncreasing the width of the gear allows the reduction of unit load under constant torque when the gear train is allowed. Reduce geardeflection, reduce noise excitation, thereby reducing transm

19、ission noise.Study on H Austria Paz Germany showed that constant torque, small aspect ratio gear noise high gradient curve width. At the same time, increasing the tooth width can increase the bearing capacity of the gear.pitch and pressure angleDistance can ensure more teeth tooth contact gear overl

20、ap increase, reduce the single gear deflection, reduce transmission noise, improve the transmission accuracy. Because the contact angle of the gear and the lateral overlap ratio of the gear are larger, the running noise is small and the accuracy is high.running speedAccording to the test of German H

21、 Austria Paz, along with the gear speed increasing, the noise level.gear box structureThe experimental results show that the cylindrical box isbeneficial to shock absorption, and the noise level of the ordinary structure gear box is higher than that of the cylindrical noise box under the same condit

22、ions as other 6dB. The resonance test of the gear box is carried out to find out the resonance position and increase the proper bar (plate), which can obviously reduce vibration and reduce noise. Multistage gear drive requires instantaneous transmission ratio as small as possible, has guaranteed smo

23、oth transmission, shock and vibration, low noise.Analysis of acoustic radiation characteristics of 6. gearsWhen selecting gears with different structural forms, the acoustic radiation model is established for the specific structure, and the dynamic analysis is carried out to evaluate the noise of th

24、e gear train system in advance. According to the different requirements of users (using place, whether the unmanned operation, whether in the city, the ground and underground buildings have no specific requirements, if there is no noise protection, or other specific requirements) to meet.Manufacturi

25、ng reasons and Countermeasureserror effectThe error of tooth profile, the pitch error and the tooth orientation error are the main errors of the transmission noise. It is also difficult to guarantee the accuracy of gear transmission.The gear with small tooth profile error and small surface roughness

26、 is smaller than the ordinary gear under the same test condition 10dB. In the same test condition, the noise level of the gear with small pitch error is 6 to 12dB smaller than that of the ordinary gear. But if there is a tooth pitch error, the effect of the load on the gear noise will be reduced.The

27、 error of the gear will lead the transmission power not to be transmitted across the whole tooth width, or to the end face or the end face of the steering gear of the contact region, because the local force increases, the gear teeth are bent and the noise level is increased. But at high load, the to

28、oth deformation can partly compensate for the tooth orientation error.The generation of gear noise is directly related to the transmission accuracy.assembly concentricity and dynamic balanceThe misalignment of the assembly will lead to the unbalance of the shafting operation, and the noise will be a

29、ggravated due to the meshing of the teeth and the half edge of the teeth. The imbalance in the assembly of high precision gear drive will seriously affect the accuracy of the drive system.tooth surface hardnessWith the development of gear hardened surface technology, its bearing capacity, small volu

30、me, light weight and high transmission precision make its application field more and morewidely. But in order to obtain hardened surface, the carburizing hardening causes the gear to deform, which leads to the increase of the gear noise and the shortening of the service life. In order to reduce nois

31、e, it is necessary to finish the machining of the tooth surface. At present, in addition to the traditional grinding method, and the development method of scraping a hardened, by modifying the tooth top and root, or the tooth wheel are active and passive transfer of small, to reduce the gear meshing

32、 in and out of shock, thereby reducing gear transmission noise.FourSystem index verificationIn the machining accuracy of parts before assembly and the selection method of spare parts (complete interchangeability, matching, matching, single etc.) will affect the precision grade to the system after th

33、e assembly, the noise levels also affect the scope, therefore, after the assembly for the calibration of the indicators system (or calibration), is the key to noise control system.Installation reasons and Countermeasuresvibration reduction and blocking measuresWhen the gear drive system is installed

34、, the resonance between the fuselage and the base support and the connecting parts shall be avoided as far as possible and the noise will be generated. The gear transmission system often occur one or a few gearsresonate in certain speed range, in addition to the design and installation of reason, wi

35、thout empty test uncovered resonant position. And take corresponding vibration reduction or blocking measures have a direct relationship. Gear transmission system with low transmission noise and vibration of certain requirements (such as instrumentation), with the high toughness, high damping materi

36、als (such as research and Design Institute of metallurgical materials based on epoxy resin mortar) to reduce noise and vibration.geometric accuracy adjustmentThe installation of geometric accuracy does not meet the standard requirements, resulting in the resonance transmission system, resulting in n

37、oise, it should be installed in the improvement of technology, the increase of tooling, to ensure there is a direct relationship between the overall quality of assembly personnel.parts looseAt the time of installation due to loosening of the individual components (such as bearing preload mechanism,

38、shaft positioning mechanism, fork limit mechanism), cause the system positioning, mobile non normal meshing, shafting, vibration and noise. The series must be designed from the design structure, as much as possible to ensure the stability of the connection of various institutions, the use of a varie

39、ty of ways of connection.drive parts damagedAt the time of installation damage due to improper operation transmission parts, cause the system motion inaccuracy or motion instability; high speed moving parts due to the damage to the oil film vibration caused by moving parts; dynamic balance; both vib

40、ration and noise. These reasons must be paid attention to and avoided as much as possible during the installation process. For damaged parts that cannot be repaired, they must be replaced to ensure a stable level of noise.Reasons and Countermeasures of service and maintenanceThe correct use and main

41、tenance of the gear drive system can not reduce the system noise level and guarantee the transfer accuracy, but it can prevent the deterioration of the index and increase the service life.drive system internal cleaningThe cleanliness of the transmission system is the basic condition to ensure the no

42、rmal operation of the gear. Any entry of impurities and dirt will affect and damage the gear drive system, which will eventually lead to noise and damage the drive system.the operating temperature of the system operating normallyEnsure the normal operating temperature of the transmission system, pre

43、vent the system from deformation due to excessive temperature rise, and cause abnormal meshing, so as to prevent noise from increasing.timely lubrication and proper use of oil productsImproper lubrication and incorrect use of grease will cause immeasurable damage to the system. Ensure that the syste

44、m is timely and correct lubrication, the system can be maintained in a certain range of noise levels, and delay deterioration trend. High speed gear, the friction of the tooth surface will produce a large amount of heat, improper lubrication will lead to damage to the gear, affect the accuracy, nois

45、e will increase. The design requires that the gear pair have a proper clearance (the clearance between the non working faces of the gear teeth to compensate for thermal deformation and storage of grease). The correct use and selection of grease can ensure the safe and effective operation of the syst

46、em and stabilize the noise level.correct use of gear movement systemAccording to the normal operation order of the system, it can avoid the damage and damage of the system to the maximum extent and guaranteethe stable noise level. The system is used in the normal load range ofthe system, because the

47、 transmission noise of the gear transmission system increases with the increase of the load.regular maintenanceRegular maintenance (oil change, replacement of worn parts, fasteners, loose parts, removal of sundries in the system, adjustment of clearance to standard values, verification ofgeometric a

48、ccuracy, etc.) The system can improve the ability to resist noise degradation,Maintain system stability.conclusionGear noise control is a system engineering, it relates to the gear design, manufacture, installation, use and maintenance of the entire process until the update, it is not only the desig

49、ner, manufacturer, also put forward many requirements for the installation and use of maintenance, any of the above link has not been effectively controlled, gear noise control will to failure.Two, gear working characteristics(I)Contact type and friction characteristics of gears (see table)Contact t

50、ype and friction characteristics of gears (see table)Gear type, contact form, main friction characteristicsSliding and rolling of spur gearSliding and rolling of herringbone gearRolling and sliding of bevel gearRolling and sliding of straight teethRolling and sliding of curved teethWorm and worm poi

51、nt slidingSliding and rolling of hyperbolic gearPoint slip of helical gear(two) the working characteristics of gears:Different types of gears with different characteristics, such as: gear, tooth contact line is a parallel with the axis line, the gear meshing is along the tooth width at the same time

52、, at the same time or separately, so easily lead to shock and noise. In order to overcome this shortcoming, helical teeth, helical teeth, curved teeth, tapered teeth and hyperbolic teeth are generated to achieve smooth transmission and reduce impact and noise. At the same time, the gear meshing area

53、, the length of the contact line than spur gears, and at the same time, there are a few teeth mesh at the same time, part of the tooth meshing, thus lower than the pressure on the tooth surface, improve the bearing capacity of gear transmission, and prolongs the service life.(three) working conditio

54、ns of gears;With the rapid development of modern industry, appear special and heavy and high-speed, high load equipment, transmission gear has become increasingly harsh conditions, especially inthe automotive industry, aviation industry and other outstanding performance, working conditions of gear b

55、ox deceleration box and othergeneral industrial gear is moderate. In short gear in different operating conditions,circumferential speed of the meshing gear, the gear and the pressure at work when the oil temperature is different, the meshing pressure is 0.8 4Gpa, circumferential speed gear is 5 100m

56、/s, the operation temperature is between 40 200 C.Three gear damage(I)Gear damage formThe form of gear damage can be divided into four types: adhesion wear, abrasive wear, fatigue wear and corrosion wear. The four types of wear are shown under different operating conditions (torque and speed etc.)(two)The main cause of the damageWhen the friction in the process of operation, one is by the lubricating oil viscosity is too small, low speed, the load is too large, not oil film; the second is the circumferential speed is too