Summary of the invention
The technical problem to be solved by the present invention is to for above-mentioned to the great failure of safety hazard, for timely early warning
Failure and the system structure internal cause for releasing the above-mentioned failure of generation, the invention proposes " a kind of non-gear end of reduction prime mover is illegal
The diagnosis and repair method of Rubbing faults ".
The technical solution adopted by the present invention to solve the technical problems is:
A kind of diagnosis and repair method reducing the illegal Rubbing faults of the non-gear end of prime mover, uses existing onboard diagnostic system
Non- increment bearing roller end face failure is detected, the diagnosis and repair for reducing the illegal Rubbing faults of the non-gear end of prime mover
Method,
Step 1, when onboard diagnostic system detects non-increment bearing roller end face failure, or monitor roller circumference,
When inner ring, outer ring are more than the failure of limits value, then alarm immediately, it is desirable that on-call maintenance after Hui Ku, and propose to release prime mover
It is directed toward the maintenance requirement of the strong axial force of non-increment;
Step 2 is speed-frequency or the failure punching of its integral multiple when onboard diagnostic system detects that frequency spectrum occurs in non-increment
It when hitting, then alarms immediately, it is desirable that repair immediately, and propose to release that the maintenance of the superpower axial force of the non-increment of direction of prime mover is wanted
It asks;
Step 3, when onboard diagnostic system detects that the temperature that non-increment occurs is more than that environment temperature reaches " temperature rise limitation
Value " or when " temperature limit value ", then alarm immediately, it is desirable that repair immediately, and propose to release prime mover the non-increment of direction it is super
The maintenance requirement of strong axial force.
Further, in the step 3, temperature rise limits value is 55 degree, and temperature limit value is 90 degree.
Further, the method for the superpower axial force problem of the non-increment of direction for releasing prime mover is: adjusting former movable tooth
The depth of parallelism of passive tooth wheel shaft that prime mover shaft where wheel is engaged with former moving gear is to meeting regulation.
Further, the depth of parallelism of adjustment prime mover shaft and passive tooth wheel shaft is to the method for meeting regulation first is that checking static
The depth of parallelism simultaneously is adjusted to meet regulation to regulation person is not met.
Further, the depth of parallelism of adjustment prime mover shaft and passive tooth wheel shaft is to the method for meeting regulation second is that checking dynamic
The depth of parallelism simultaneously is adjusted to meet regulation to regulation person is not met.
Further, solve the dynamic depth of parallelism do not meet regulation method first is that adjustment passive tooth wheel shaft passive bearing diameter
To gap to meeting regulation.
Further, solve the dynamic depth of parallelism do not meet regulation method second is that adjustment passive tooth wheel shaft passive bearing axis
To gap to meeting regulation.
Further, it is driven axle when guaranteeing installation that the adjustment passive bearing radial clearance dynamic depth of parallelism, which meets the method for regulation,
It holds radial clearance and meets regulation.
Further, adjustment the passive bearing axial gap dynamic depth of parallelism meet regulation method first is that guarantee installation when quilt
Dynamic bearing axial gap meets regulation.
Further, the adjustment passive bearing axial gap dynamic depth of parallelism meet the method for regulation second is that, it is passive to prevent
The inner ring of bearing inner ring when bearing axial force slides axially and increases the axial gap of passive bearing, increases inner ring axial
Stop measure, or increase installation interference pretightning force.
The beneficial effects of adopting the technical scheme are that
Using the present invention, not only solves and realize that preventing the illegal Rubbing faults development of the non-gear end of prime mover is the pre- of accident
Alarm method problem, and provide after diagnosis issues alarm, carry out the problem of scientific maintenance is instructed according to Fault Mechanism Analysis;
Accident is not only prevented, and leads to the outer of failure from " temporary solution " of general alternate maintenance progress to the elimination based on system engineering
It because of condition its " effecting a permanent cure ", realizes and not only ensures safety, but also reduce or prevent failure multiple, reduce spare unit consumption, reduce maintenance cost
With the economic benefits such as raising equipment utilization rate.
Specific embodiment
Below in conjunction with drawings and examples, the invention will be further described.
First of all, it is necessary to find the most first occurred sign of the illegal Rubbing faults of the non-gear end of early warning prime mover, especially exist
Bearing, which not yet destroys and illegally touch before mill not yet occurs, characterization, will develop as bearing failure and the illegal sign touching mill and occurring
Million, in identification, diagnosis, confirms and issue alarm after the sign immediately.
It correctly finds bearing failure and illegally touches the theoretical principle for the sign that mill occurs and method is: carrying out mechanical knot
Structure/Fault Mechanism Analysis.This measure can not only determine " most first occurred sign ", provide shortcut for early warning failure, and due to
Disclose " mechanical structure/failure mechanism " and can determine " releasing the system structure internal cause for generating above-mentioned failure ", determine maintenance or
The improved method of structure.
Hereby " mechanical structure/failure mechanism " of " the illegal Rubbing faults of the non-gear end of prime mover " is analyzed as follows:
The non-gear end mechanical structure of prime mover as shown in Fig. 1, prime mover shaft tie up to non-gear end and are supported on transition
Fit system is installed on the bearing 2 of casing 1;There are two flange 3, inner ring a flange 4 on the right for the outer ring of the bearing 2,
There is a shaft shoulder 5 on axis, withstand bearing inner ring, there is an outer ring pressing ring 10 on the outer ring left side, by the end cap 11 being mounted on casing 1
It pushes down, to compress outer race;In order to realize bearing seal, there is the sealed end that shaft end is pressed on by shaft end screw 8 in shaft end
Lid 7, end cover 7 and outer ring pressing ring 10 form sealing labyrinth 6.Design has gap between shaft end screw 8 and end cap 11, to prevent two
Person touches mill.
Therefore, the reason of shaft end " illegally touching mill " occurs can only be that prime mover shafting (is illustrated by non-gear end is directed toward
The left side) superpower axial force.The axial force acts on 2 inner ring of bearing by the shaft shoulder, acts on roller by the right flange of inner ring
9, the left flange of outer ring is acted on by roller 9, forces the deformation of outer ring pressing ring 10 or/and end cap deformation, bearing to be slided to the left, then
Shafting is released to the left, is forced the contact of shaft end screw 8, is touched mill end cap 11.
According to above-mentioned Analysis on Mechanism, identify that the information of superpower axial force is:
1, the roller for being directed toward the responsive to axial force of non-gear end in bearing is axial, makes roller relative to the right flange of inner ring and outer
Sliding friction occurs for the left flange of ring, and roller end face damage is caused to generate failure impact.The feature frequency of the roller end face fault message
Spectrum Fgd is:
Fgd=(D02-d2)·fn/(2·D0·d)
Wherein, D0 indicates bearing central diameter, and d indicates that roller diameter, fn indicate that axis turns frequency, therefore, work as onboard diagnostic system
Monitoring, diagnosing finds the characteristic frequency spectrum for meeting roller end face fault message, that is, detects non-increment bearing roller end face failure, and
Reach the rank of early warning or more, then issue alarm immediately, it is desirable that maintenance in due course issues the non-increment of direction for releasing prime mover
The maintenance direction prompt of strong axial force.
2, or because roller end face and outer ring flange are smooth, roller end face does not have projecting point, cannot draw and touch mill outer ring flange
Roller end face impact is issued, but inner and outer rings flange has projecting point or because the damaged inner and outer rings flange of the powerful extruding of axial force generates damage
Wound, is impacted by roller end face, then issues inner and outer rings impact alarm;Or roller takes place along and rolls working face rupture and roll
Sub- circumference (rolling is double) impact;I.e. when monitoring that roller circumference, inner ring, the impact value of outer ring are more than limits value, report is issued immediately
It is alert, it is desirable that maintenance in due course issues the maintenance direction prompt for releasing the strong axial force of the non-increment of direction of prime mover.
3, but since roller end face and inner and outer ring flange are all by precision machined, due also to containing lubrication in bearing
Rouge, therefore when occurring being directed toward the axial force of non-gear end, roller does not break down immediately, or the axial direction because being directed toward non-gear end
Power occurs and very powerful suddenly, and the axial force and outer race pressing ring and end cap are not enough to contend with, bearing is with outer ring by entirety
When releasing to the left, bearing roller end face not yet generates damaged and failure impact information, but has occurred and that shaft end screw is touched with end cap
Mill, at this moment, the strategy obviously failure of the waiting bearing roller end face fault message of " trusting to chance and strokes of luck ".And it can identify the catastrophe failure
Information, be exactly that shaft end touches that mill information or temperature are more than 55 degree of environment temperature or temperature is more than 90 degree.This is because shaft end spiral shell
It is roughing face on the inside of ailhead and end cap, as long as being in contact both in axis rotation, causes strong, axis each rotation
Friction that at least generation is primary, that frequency turns frequency or its integral multiple equal to axis is impacted.
Therefore, it is a kind of reduce the illegal Rubbing faults of the non-gear end of prime mover diagnosis and repair method must also be, when vehicle-mounted
Diagnosis diagnostic system detects when the failure impact of speed-frequency occurs in non-increment or temperature is more than 55 degree of environment temperature, or temperature
It when degree is more than 90 degree, then alarms immediately, it is desirable that repair immediately, and propose to release the superpower axial force of the non-increment of direction of prime mover
Maintenance direction.
If decomposing and after finding that non-gear end bearing issues roller end face fault alarm to bearing alternate maintenance
" failure " bearing may have existed failure, for example, roller chamfer be worn broaden, there is polishing scratch in roller end face, cracked;
But the roller end face also having only has brighten or circular scratch.At this moment, often referred to as " mistaken diagnosis ".And more renewing bearing
Later, roller end face alarm still may occur.Here it is the processing only executed to bearing " temporary solution ", and are not carried out and " release former
The consequence of the processing that effects a permanent cure of the strong axial force of the non-increment of direction of motivation ".
4, " mechanical structure/failure mechanism " analysis is found, axis suffered by prime mover of most of direct geared transmission
Xiang Li, be the primary shaft 17 of former moving gear 14 and the driven axle 13 of driven gear 12 it is not parallel caused by.Such as occur attached
When shown in Fig. 2 not parallel, the thrust AC of 12 pairs of driven gear former moving gears 14 is not orthogonal to primary shaft 17, generates one in parallel
In primary shaft 17, the component BC of the non-gear end of direction, born by non-increment bearing 15, because as shown in figure 3, in order to resist gear
Powerful radial thrust when engagement, increment bearing 16 be chosen as being not subject to axial force, inner ring there is no the U-shaped bearing of flange;It pushes away
The radial component AB perpendicular to primary shaft that power AC is generated, is born by increment bearing 16, is parallel to primary shaft 17, is directed toward non-gear
The component BC at end is exactly axial force described in Fig. 1, is the primary factor for leading to the various failures of non-gear end.
It is therefore proposed that a kind of diagnosis and repair method for reducing the illegal Rubbing faults of the non-gear end of prime mover, the releasing are former
The method of the superpower axial force problem of the non-increment of direction of motivation is: adjust prime mover shaft where former moving gear with former movable tooth
The depth of parallelism of driven axle where taking turns the driven gear of engagement is to meeting regulation (but the axis depth of parallelism and axis of the defined of various machinery
Axial direction, the regulation of radial clearance and disunity are held, and certain regulations there are incomplete factor due to constantly adjusting).
The depth of parallelism of driven axle where the driven gear that primary shaft where adjusting former moving gear is engaged with former moving gear
To regulation is met, it is to ensure that first and checks static parallel degree and be adjusted to meet regulation to regulation person is not met.Because static
There are not parallel, then there will be fixed, lasting axial force.
5, if two teeth are only not present when due to static state in the static depth of parallelism inspection for carrying out primary shaft and driven axle
Mutual radial thrust is taken turns, the axis of two gears is respectively positioned on the center vertical line of respective spring bearing, as long as then two bearings
Axis it is parallel, check the result of the two axis depth of parallelisms i.e. parallel.If but the very big radial clearance of bearing presence, two
The mutual radial thrust of gear dynamic results in the center of two axis away from increase, since the driven axle of driven gear is always by two axis
Support is held, if the gap of the two bearings is different, the distance that driven axle both ends try to exit from primary shaft is just different, then two axis
The depth of parallelism be just destroyed.
Therefore, the diagnosis and repair method of the illegal Rubbing faults of a kind of non-gear end of reduction prime mover, adjustment are parallel
Spend the method for meeting regulation second is that checking the dynamic depth of parallelism and being adjusted to meet regulation to regulation person is not met.
6, even if the gap of two spring bearings 18 of driven axle 13 is identical, but because of the gear train assembly of several machinery
Former moving gear 14 is designed as to be driven the driven gear 12 of 13 one end of driven axle, as shown in attached drawing 4, attached drawing 5,13 both ends of driven axle
External output torque and by the thrust for being directed toward primary shaft 17, then the driven axle 13 at driven gear end is to far from primary shaft 17
Direction offset, and the other end of driven axle 13 is then deviated to the direction close to primary shaft 17, then, the depth of parallelism of two axis is also broken
It is bad.The measure of solution undoubtedly reduces the radial clearance of the spring bearing of driven axle 13 to the lower limit that can be tolerated.
Therefore, the diagnosis and repair method of the illegal Rubbing faults of a kind of non-gear end of reduction prime mover solves dynamic
It is that the depth of parallelism does not meet the method for regulation first is that the radial clearance of adjustment passive tooth wheel shaft passive bearing is to meeting regulation.
8, in order to resist the axial force that driven axle is subject to, two sets of passive bearings of several driven axles use taper roller axis
It holds.Correct installation method is as shown in Fig. 6, to enable that inner and outer ring is installed to radial clearance and axial gap meets regulation.Because
If installation is not in place, as shown in Fig. 7, inner ring is not mounted to the positioning shaft shoulder (step) against driven axle, so that by
Moving axis and its bearing can be between two motionless outer rings along axial left and right activity, i.e. the axial gap of driven shaft bearing increases
Greatly, then radial clearance also increases with it, and it is parallel with driven axle that attached drawing 4, the destruction primary shaft of attached drawing 5 will occur during exercise
The consequence of degree.Especially certain driven axles do not have positioning shaft shoulder, such as attached drawing 8, then passive bearing installed on axis not only all according to
By the pretightning force of interference fit, and it is easy to happen the problem bigger than normal of axial gap caused by the inaccuracy of position.Therefore in maintenance
If checking, discovery axial gap increases, and should be adjusted to meet regulation.
Therefore, the diagnosis and repair method of the illegal Rubbing faults of a kind of non-gear end of reduction prime mover solves dynamic
It is that the depth of parallelism does not meet the method for regulation second is that the axial gap of the passive bearing of adjustment passive tooth wheel shaft is to meeting regulation.
Obviously, if replacement passive bearing, reinstalls new bearing, then should be guaranteed that and be installed in place, therefore, one kind subtracts
The diagnosis and repair method of few illegal Rubbing faults of the non-gear end of prime mover, guarantee when being changed to new bearing passive bearing it is radial,
Axial gap dynamic meet regulation method first is that guarantee installation when passive bearing radially, axially gap meets regulation.
It is therefore analyzed outside the illegal Rubbing faults of the non-gear end of motor and its internal cause of 1, No. 6271 vehicles of Application Example
It is commonly installed a tachometer disc 19 in the shaft end of the non-gear end of locomotive motor, tachometer disc 19 is equipped with tachometer disc 19
Only has the gap of very little between the end protective cover 20 of protective cover 21, tachometer disc 19 and motor, such as attached drawing 9.In the vehicle of No. 6271 vehicles
Monitoring system is carried in 11 points of 25 minutes detection signals to motor (prime mover) non-gear end (55) on March 4, often in electricity
There are 2 clusters and touches the impact information of mill in arbor each rotation, though reach 29dB, due to a lack of higher-order spectrum without issuing early warning, but
There is 61 degree of temperature rise alarm, such as attached drawing 10;Since tachometer disc 2 cluster projecting point most outstanding is worn away and other secondary protrusions
2~4 clusters etc. it is high when or end cap 2 cluster projecting point most outstanding when being worn away with other 2~4 cluster outstanding grade height, just exist
It separates that 4 clusters occurs in existing motor shaft each rotation and 6 clusters touch the impact information of mill and reach 25dB on March 4 18: 15, while also occurring
59 degree (the high 57 degree of limits values more than 55 degree of environment temperature compared with 2 degree) of temperature rise alarm.Such as attached drawing 11.
According to a kind of three key steps of diagnosis and repair method for reducing the illegal Rubbing faults of the non-gear end of prime mover:
Step 1, when onboard diagnostics diagnosis detect non-increment bearing roller end face failure when, or monitor roller circumference,
When inner ring, outer ring are more than the failure of limits value, then alarm immediately, it is desirable that on-call maintenance after Hui Ku, and propose to release prime mover
It is directed toward the maintenance requirement of the strong axial force of non-increment.
Step 2 is speed-frequency or the event of its integral multiple when onboard diagnostics diagnostic system detects that frequency spectrum occurs in non-increment
It when barrier impact, then alarms immediately, it is desirable that repair immediately, and propose to release the dimension of the superpower axial force of the non-increment of direction of prime mover
Repair requirement.
Step 3, when onboard diagnostics diagnostic system detects that the temperature that non-increment occurs is more than that environment temperature reaches " temperature rise
It when limits value " or " temperature limit value ", then alarms immediately, it is desirable that repair immediately, and propose to release the non-increment of direction of prime mover
Superpower axial force maintenance requirement.Wherein, temperature rise limits value is 55 degree, and temperature limit value is 90 degree.
The detection information of the non-gear end of the motor of the vehicle, has met step 3, and the feature of step 2 occurs, therefore
It " must propose to release the maintenance direction of the superpower axial force of the non-increment of direction of prime mover (being herein motor) ".
To the comprehensive analysis of transmission system, the superpower axial force of the non-increment of direction for releasing prime mover according to the present invention
The method of problem is successively:
A, the depth of parallelism of the passive tooth wheel shaft that the prime mover shaft where adjusting former moving gear is engaged with former moving gear is to according with
Close regulation.
But it can not can be carried out in driving;Even if parking, also almost impossible progress.
B adjusts the depth of parallelism to the method for meeting regulation first is that checking static parallel degree and adjusting to regulation person is not met
To meeting regulation.It can not can be carried out in driving;Even if parking, also almost impossible progress.
C adjusts the depth of parallelism to the method for meeting regulation second is that checking the dynamic depth of parallelism and adjusting to regulation person is not met
To meeting regulation.Conventional parallelism detection, it is impossible to carry out dynamic monitoring in driving.
D adjusts the radial clearance of passive tooth wheel shaft passive bearing to meeting regulation.Enough, exact card is not being obtained
It is adjusted according to not at all possible decision before;Even if intend adjust passive bearing radial clearance to regulation is met, do not have yet " be
It is no to meet regulation " static detection means.
E adjusts the axial gap of passive tooth wheel shaft passive bearing to meeting regulation.Equally, do not obtain it is enough, definite
Evidence before not at all possible decision be adjusted;Even if intending the radial clearance of adjustment passive bearing to regulation is met, do not have yet
There are the static detection means of " whether meeting regulation ".
Then, the important basis of maintenance decision is must to confirm that " radial clearance does not meet regulation " occurs in passive bearing
Or the phenomenon that " axial gap does not meet regulation ".In being to continue with driving, passive bearing and the non-gear end of motor are monitored.
The basis of above-mentioned rational analysis exists really: in 3 points of 14 minutes detection signals on March 2, it is passive to have had already appeared
1 grade of inner ring alarm of 54 bearings of one of bearing, such as attached drawing 12.
In particular, April 14, be alternately present the non-gear end of motor (55) touches mill and 54 passive bearings 6 times a week
1 grade alarm.Such as attached drawing 13.But designers think: the mounting means of passive bearing as shown in Fig. 14 be it is most scientific,
Because as shown in Fig. 15, analyzing from static mechanical, two sets of passive bearings are impossible to mobile to both ends, it is also not possible to centre
It is mobile.Figure 14, Tu15Zhong, label 22,23 respectively indicate two passive bearing axle suspension bearings, and 24 indicate axle suspension bearing seat, and 25 indicate tooth
Wheel, 26 indicate wheel, and 27 indicate that vehicle is taken out.
But from the structural analysis of bearing, such as attached drawing 16, the roller length of tapered roller bearing compared with two flanges of inner ring
Length is small, that is, showing the bearing, there are axial gap JX.
Then, it there is following Mechanics Phenomenons:
When vehicle starts snake, when right wheel 26-1 (though bumping against the unexpected bullet of right track to the left side because slowly moving to right)
When applying axial force to the left suddenly to axle 29,54 inner ring are so moved downward with aixs cylinder, since roller length is less than inner ring
Raceway width, with respect to 54 bearing inner rings slide to the right flange of inner ring to 54 bearing rollers immediately, and (it is internal that this may cause roller
The scratch of ring and outer ring or load mould!) and roller finally compresses outer ring, applies thrust to the left to irremovable axle suspension bearing seat 24,
And it is transmitted to the outer ring of 53 axle suspension bearings;Since the inner ring of 53 bearings is also by the axial force to the left of axle, therefore 53 axis
The state that inner and outer ring is in mutual not axial force is held, then, due to centrifugal force, 53 rollers are radially outer to be moved, directly
The left flange of inner ring is nestled up to the left side of roller, such as attached drawing 17.
When left wheel (though because slowly move to left but bump against the unexpected bullet of left track to the right) applies to the right axle suddenly
When axial force, axial force to the right because roller against left flange and compresses inner and outer ring, is just applied to axle suspension bearing seat, and compel by 54
So that roller is abraded 54 outer races to the right, and if 53 rollers are just fallen on the dent of abrasive inner ring just now at this time,
It cannot be moved to right with inner ring and axis, then roller hits the left flange of 54 inner ring, moves to left 54 bearing inner rings with respect to axle, such as attached
Figure 18.
Proving the evidence of above-mentioned thrust is: since 1 grade of alarm occur in 54 bearings, be decomposed maintenance.It is found after decomposition: interior
Occur on ring raceway according to the equally distributed scratch of roller number or impression;There is axial scratch trace in the inner hole of inner ring,
Such as attached drawing 19.
Occur above-mentioned inner race axially scratch demonstrate the bearing axial gap it is bigger than normal, and this is (in conjunction with front
Reasoning) also increase necessarily the radial clearance dynamic of bearing, both of which will cause the dynamic of driven axle (axle) and motor shaft
It is not parallel, cause the axial force for being directed toward the non-gear end of motor, non-gear end is forced to occur illegally to touch mill early warning and temperature rise alarm.And
After 54 bearing inner rings move right, then axial direction, the radial clearance of bearing are more increased, more increases the non-gear end of motor
The external cause for illegally touching mill occurs.
2,6269 vehicle of Application Example, 1 axis occurs the non-gear end of motor and illegally touches the internal cause of mill, External Cause Analysis
The vehicle-mounted monitoring system of 6269 vehicles had issued the outer ring of 14 axle suspension bearings, inner ring inside early warning March 7, such as attached
Figure 20;The motor shaft each rotation for the non-gear end of motor then occur occurs the illegal of 4 clusters impact and touches mill signal, 27 sunrise in March
The 4 ranks impact of existing 15dB, such as attached drawing 21;There is outer ring early warning April 12 in 14 axle suspension bearings, such as attached drawing 22, occurred April 15 in
Ring, 1 grade of outer ring alarm, such as attached drawing 23.
After on May 25th, 2016 when factory decomposes and repairs, it is found that 14 inner ring appearance are uniformly distributed according to roller spacing
Axial scratch, identical with 54 inner ring failures described in embodiment 1, also there is similar scratch in outer ring.
Regrettably, after maintenance on May 25, after putting into operation within Yu Liuyue 1st soon, and there is inner ring (scratch) event
Hinder information, such as attached drawing 24, is only transported during first internal early warning record that last inside early warning on May 25 is recorded June 1
It has gone less than 300kM;And 1 grade of alarm occurred June 7, such as attached drawing 25.In particular, new bearing appearance causes inner ring to be alarmed
The big factor of axial gap, continue to be that gear generates strong axial force, the non-gear end of motor caused not only to continue shaft end occurs to touch
The early warning of mill such as attached drawing 26, and also cause roller and squeeze destruction outer ring flange, so that newly producing outer ring early warning, such as attached drawing
27。
Thus speculate and think: the non-increment of motor being caused to occur touching the factor that mill, high temperature, outer ring flange are damaged being that axle seizes
Hold it is axial it is bigger than normal than radial clearance caused by and therefore lead to that axle suspension bearing inner and outer ring abrades and its axial diameter is reinforced in inner ring displacement
Axle caused by gap and the motor shaft depth of parallelism are deteriorated, and then cause the axial force for being directed toward the non-gear end of motor.And replace axis
After holding soon, and continue to occur the fault alarm of the non-increment fault message of motor and axle suspension bearing itself, then show: or bearing
Design axial-radial gap it is too big or there are installation deviations caused by bad mounting process.