CN103353366A - Method for dynamic measurement of contact pressure of friction pair of circular plate - Google Patents

Method for dynamic measurement of contact pressure of friction pair of circular plate Download PDF

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CN103353366A
CN103353366A CN2013103166042A CN201310316604A CN103353366A CN 103353366 A CN103353366 A CN 103353366A CN 2013103166042 A CN2013103166042 A CN 2013103166042A CN 201310316604 A CN201310316604 A CN 201310316604A CN 103353366 A CN103353366 A CN 103353366A
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friction pair
pin
friction
contact
strain
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CN103353366B (en
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王延忠
魏彬
宁克焱
韩明
郭超
吴向宇
李圆
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Beihang University
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Beihang University
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Abstract

The invention relates to a method for dynamic measurement of a contact pressure of a friction pair of a circular plate. The method comprises the following steps: analyzing a processing technology requirement and a loading structure characteristic of a friction pair; selecting a pin with the same material attribute as a dual disc; determining distribution of the pin at the dual disc and a matched dimension of a dual disc pin hole according to the characteristic of the loading structure; carrying out secondary processing on the surface of the dual disc to obtain an attribute similar to that of an original dual surface; and carrying out strain measurement on the pre-buried pin so as to obtain a contact pressure of the friction pair at the zone. According to the invention, static and dynamic testing on the contact pressure of the friction pair can be carried out; on the premise that a contact state of a surface of the friction pair is not changed, static-dynamic testing of the contact pressure is realized; and when a precise pressure boundary condition of the friction pair is determined, a theoretical basis is provided for the dynamic design of the friction pair.

Description

A kind of for the secondary contact dynamic measurement method of disk friction
Technical field
The present invention is a kind of for friction pair contact dynamic measurement method, belongs to the secondary pressure of contact surface field of measuring technique of endless-track vehicle transmission field clutch friction.
Background technology
The high-energy-density friction driven system is the key of high-performance transmission, and its notable feature is high-power, high rotating speed, and friction pair is because its excellent wearing quality and higher thermal capacitance are widely used in the transmission field of endless-track vehicle.Cu base powder metallurgy friction pair comprises brakes and clutches, is operated in many stress combinational environment, and be the principal element that affects the friction pair rubbing characteristics as three bound of parameter-pressure, speed, temperature, also be the important references in the design of friction pairs process.Present stage speed and temperature boundary Measurement accuracy by experiment, and the test of pressure boundary is the Focal point and difficult point in three boundary surveies always, dynamic test is more difficult, and the design field at Wet-type friction slice never has the maturation method that effective and reliable friction pair pressure of contact surface is measured at present.Friction pair is carried out the three-dimensional modeling simulation add the Main Means that press contacts is the acquisition contact.The method of thin film sensor is puted up owing to changed the surface in contact characteristic and can not carry out kinetic measurement in the surface that present stage adopts, and can not adapt to the dynamic design of endless-track vehicle friction pair, can't satisfy the designing requirement of new model new equipment friction pair.
For a long time surface of friction pair pressure survey difficulty mainly concentrates on following several respects: (1) measuring sensor participates in contact, has changed the contact performance of surface in contact, and truly contact situation of friction pair can not get reflection, and the measurement of contact is not accurate enough; (2) can't realize for friction pair from separating, touch the kinetic measurement of sliding overall process of rubbing; (3) because the secondary contact distribution range of wet friction is little, and conventional pressure sensitive paper method precision is low, be difficult to effectively reflect the pressure distribution state of surface in contact.
Summary of the invention
Technical matters of the present invention: be the problem that to measure in order to solve the friction pair pressure boundary condition that exists in the prior art, provide a kind of for the secondary contact dynamic measurement method of disk friction, the difficulty that the pressure of contact surface that has effectively solved current friction pair distributes and can't truly obtain, be not change under the prerequisite of surface of friction pair contact condition, realized the quiet dynamic test of contact, when having determined friction pair accurate pressure boundary condition, for the friction pair dynamic design provides theoretical foundation.
Technical solution of the present invention: a kind of for the secondary contact dynamic measurement method of disk friction, performing step is as follows:
Step 1, determine working condition under the friction pair duty and the loading structure characteristics of friction pair, obtain the physical dimension of friction pair, determine that according to the manufacturability requirement of the friction pair that will measure the roughness of friction pair surface in contact requires and the processing request of surface planarity;
Position distribution and measuring point quantity N rapid two, determine the measurement point on the friction pair antithesis sheet according to the physical dimension of the loading structure characteristics of analyzing the friction pair that obtains in the step 1 and friction pair;
Step 3, the Friction Disk Surface roughness and the flatness requirement that obtain according to the step 1 analysis require to determine diameter D and the length L of pin in conjunction with size, antithesis sheet thickness, foil gauge size and the measuring accuracy of friction pair surface in contact, and the method for determining is as follows:
Pin diameter D＜(R-r)/2, R is antithesis sheet external diameter, and r is antithesis sheet internal diameter; B/2＜L＜2B/3, B are antithesis sheet thickness, and the D that the friction surface contact friction of roughness 1.6 flatnesses 0.04 is selected should be greater than 12mm, and still minimum should be less than the width b of minimum strain sheet, and the diameter D scope of the pin of choosing is: 4-12mm; The pin of having determined diameter D and length L is embedded in the embedded hole to the steel disc that rubs;
The dimensioned pin of step 4, the pin that obtains according to step 3, and process a plane on the pin side face of cylinder, be used for pasting foil gauge, the size of processing plane should be greater than the size of foil gauge, beat the hole of pre-buried pin according to the D that has determined and L in the position of layouting of the required measured zone of antithesis sheet, tapping in the pin hole of antithesis sheet noncontact face, attacking the line degree of depth is B-L, chooses transition fit as the fit dimension tolerance of hole and pin;
Step 5, the friction pair material characteristic that obtains according to step 1, the physical dimension characteristic, the supporting construction characteristics, loading characteristics etc. are set up the three-dimensional simulation model of friction pair and loading structure thereof, three-dimensional model is carried out the finite element simulation of multi-direction pressure load, for the contact test is provided fundamental basis and the prediction of numerical range;
Step 6, determine the range of stress of friction pair surface in contact according to the simulation results of step 5, and determine the major parameter of the resistance strain gage that is suitable for this friction structure according to this scope, described major parameter comprises the initial resistance of foil gauge, sensitivity coefficient and strain limit obtain the foundation that foil gauge is selected by major parameter;
Step 7, choose and obtain suitable monitor strain sheet by step 6, the foil gauge that is adapted to the strain range of emulation gained is affixed on the plane that pin processes in advance, check whether the foil gauge resistance value is the initial resistance of resistance strain gage, if it is little that resistance shows with the initial resistance difference of resistance strain gage, the success of foil gauge paster is described, bridge joint strain operation circuit, and pack on the antithesis sheet pin in the corresponding pin-and-hole and fix with the pretension screw;
Step 8, the pairing steel sheet that assembling is finished carry out secondary processing according to worker's property requirement of the friction pair production and processing of step 1 analysis acquisition to the friction pair surface in contact, friction pair is installed to carries out break-in on the friction wear testing machine, running-in time is not less than 30min, and running in speed is determined according to the operating mode rotating speed of living in of analyzing the friction pair that obtains in the step 1;
Step 9, the sufficient friction pair of break-in is carried out quiet dynamic load, connect the resistance-strain Acquisition Instrument, by voltage index gauge zeroing circuit, and the signal transmission by bridgt circuit, obtain the stress-strain state of each measuring point of pre-buried pin place friction surface.
The present invention's advantage compared with prior art is:
(1) the present invention adopts the method for pre-buried pin, realizes the measurement of the quiet dynamic touch pressure of friction pair.
(2) the present invention is embedded in friction pair inside with measuring sensor, and the secondary processing surface has similar characteristic to original surface, has eliminated the impact of measuring sensor on contact performance itself.
(3) the present invention can realize measuring from the dynamic touch pressure that separates, touches sliding overall process of rubbing for friction pair, and this method can be measured effectively to the dynamic contact characteristic of friction pair.
(4) measuring accuracy of the present invention is high, and measuring method is simple, test point position arrangement convenience, and testing cost is lower.
(5) the present invention has effectively solved the difficulty that the pressure of contact surface of current friction pair distributes and can't truly obtain, be not change under the prerequisite of surface of friction pair contact condition, realized the quiet dynamic test of contact, when having determined friction pair accurate pressure boundary condition, for the friction pair dynamic design provides theoretical foundation.
Description of drawings
Fig. 1 is the inventive method realization flow figure;
Fig. 2 is pin-and-hole distribution engineering drawing among the present invention;
Fig. 3 is pin feature engineering drawing among the present invention, and wherein upper figure is front view, and figure below is vertical view;
Fig. 4 is that pin is just waiting shaft side figure among the present invention;
Fig. 5 is pin assembling synoptic diagram among the present invention;
Fig. 6 is the limit element artificial module of being set up by practical structures among the present invention;
Fig. 7 is FEM Numerical Simulation cloud atlas among the present invention;
Fig. 8 is the paster front elevation on pin side plane among the present invention;
1, anti-blushing agent 2, the first foil gauge 3, lead-in wire 4, hinge (sealed polyethylene plastic), 5, connection terminal, 6 soldered joints, a, plug screw b, pin c, the second foil gauge;
Fig. 9 is the paster plan view on pin side plane among the present invention;
Figure 10 is bridge circuit connection layout among the present invention;
Figure 11 is the measurement curve map of measuring point among the present invention.
Embodiment
Elaborate below in conjunction with the embodiment of accompanying drawing to the inventive method.
Theoretical research and process of the test find that all Cu base powder metallurgy friction pair exists the characteristics of contact skewness (particularly radially) at engaging process and bonding state, and the generation of these characteristics is because the characteristics of pressure structure and the common decision of surface in contact characteristic.The present invention adopts the method for pre-buried pin, realizes the measurement of the quiet dynamic touch pressure of friction pair.
In order to realize the test of friction pair contact, the processing test pin is some, need to decide according to the requirement of size, pressurization characteristics, test zone and the precision of friction pair for pin size and characteristic distributions, the size of pin diameter is directly connected to the size of the contact area of measurement, and arrangement principle should be taken into account the actual change rule of contact.Truth for the friction surface that do not affect the Cu based powder metallurgy friction wafer, beat several through holes on the surface of pairing steel sheet, the terminal tapping in hole, requirement according to paster is affixed on the steel pin side with foil gauge, steel pin is put into the through hole of pairing steel sheet, the test pin of pasting strain is embedded in the position that the antithesis sheet need to be measured contact, adopts transition fit between pin and the antithesis sheet, and end is fixed by plug screw.
The surface that embeds pin is carried out secondary processing (being generally grinding) by pairing steel sheet by technological requirement, make the surface that embeds pin have similar characteristic to former antithesis surface.Friction pair is loaded into the friction test platform, and access hyperchannel strain measurement system, for the measurement of quiet moving contact under the different operating modes, need the change sample frequency, to obtain more preferably measurement result.
As shown in Figure 1, the dynamic touch pressure method of testing specific implementation process of the pre-buried pin strain measurement of the present invention is as follows:
Step 1, definite manufacturability requirement that needs the friction pair of measurement, such as agglomerated material requirement, processing technology requirement, flatness comprising surfaceness, Friction Disk Surface, for example certain surface of friction pair adopts powder metallurgical sintering process, the friction surface grinding, flatness 0.04, roughness 1.6 etc.The analysis that requires for manufacturability mainly is the manufacturing processing technic of antithesis sheet, for the selection of the tolerance fit of antithesis sheet secondary processing and pin and pin-and-hole provides foundation.And determine working condition (being mainly load) under the friction pair duty; The physical dimension of friction disc (internal-and external diameter, thickness, frictional layer thickness etc.) and loading structure characteristics, the supporting construction characteristics when comprising friction pair work, the pressure structure characteristics, as which kind of adopts support position of bearings and loading force position and direction etc.The analysis of friction pair physical dimension, working condition and loading structure is mainly carried out abbreviation to loading structure, and the initial analysis that distributes in order to finish the friction pair contact provides the parameter support of necessity for the foundation of realistic model.
Step 2, determine that according to the characteristics (friction pair supporting construction characteristics, loading force position and direction etc.) of the loading structure of the friction pair of determining in the step 1 (the antithesis sheet is the structure that rubs mutually with friction disc to its antithesis sheet, generally be formed from steel, it and friction disc have formed friction pair jointly) on distribution and the measuring point quantity of measurement point, according to friction pair size and design feature measuring point quantity and distribution are carried out reasonable Arrangement.For near the supporting construction and the regional stress nearer apart from load(ing) point larger, cause the friction pair distortion obviously, cause the unilateral pressure distribution of friction disc and antithesis uneven significantly local, should layout more, layout and follow circumferential uniform principle, to reduce circumferential degree of irregularity; Circumferentially should decide according to testing requirement with radially measuring point and distribution, the radial pressure test is mainly for the static(al) test, and the test that the consideration circumferential pressure distributes often will realize the effect of kinetic test.In the larger zone of pressure gradient, should consider the measurement points of arranging more, layout requires to satisfy uniform principle as far as possible.The density of layouting should be determined according to the fine degree of friction disc physical dimension and measurement, the large scale friction pair can be layouted more, and more measurements of layouting are meticulousr, layout be the pressure distribution state of understanding Friction Disk Surface be purpose, do not have fixing number, generally be no more than 64.For example support for centre bearing, the friction pair structure of center loaded should be layouted at inner ring for layouting of antithesis sheet more;
Step 3, determine diameter D and the length L of pin by physical dimension and according to accuracy requirement, the material of pin is consistent with heat treatment characteristic and pairing steel sheet.Finished after friction pair measuring point quantity and the distribution character, diameter D and the length L that need to determine pin according to size and the measuring accuracy of measured zone, the diameter of pin has certain restriction, and the size of the diameter of pin is directly connected to area size and the accuracy rating of the strain testing on surface.But meticulous pin may bring the adverse consequencess such as difficulty of processing is higher, fit dimension is inaccurate, unrelieved stress is excessive.If adopted thick pin, the quantity of measuring point will be subject to certain restrictions, and the precision of measurement also can descend.The material of pin with must be consistent to the material of the steel disc that rubs, like this could the most effective pressure distribution situation that reflect truly Friction Disk Surface.
Require to determine diameter D and the length L of pin according to size, antithesis sheet thickness, foil gauge size and the measuring accuracy of Friction Disk Surface roughness and flatness, surface of contact, the method for determining is as follows:
General pin diameter D＜(R-r)/2, R is antithesis sheet external diameter, and r is antithesis sheet internal diameter; B/2＜L＜2B/3, B are antithesis sheet thickness, and the D that the friction surface contact friction of general 1.6 roughness, 0.04 flatness is selected should be greater than 12mm, and the better D that selects is less for exposure level, should be less than the width b of minimum strain sheet but minimum.The diameter D scope of the pin of choosing is generally: 4-12mm;
Need to survey the contact of 5 millimeters some contact areas, antithesis sheet thickness is 15mm, and L gets 12mm, 0.8 roughness, and the friction pair of 0.04 flatness, R are 120mm, and r is 100mm, and optional D is 5mm.The material of pin and antithesis dish (friction pair comprise frictional disk and to the antithesis dish) and material consistent; The pin of having determined diameter D and length L can be embedded in the embedded hole to the steel disc that rubs;
The plane that step 4, processing pin need to be pasted foil gauge c, process a plane on the pin b face of cylinder, be used for pasting foil gauge c, the size of processing plane should be greater than the size of foil gauge, beats the hole of pre-buried pin and tapping in the position of layouting of the required measured zone of antithesis sheet according to the D that has determined and L, as shown in Figure 5, wherein a is plug screw, and b is pin, and c is foil gauge.The length of attacking the line degree of depth and plug screw a should be L Spiral shell=L Sheet-L Pin, L wherein SheetBe the thickness of pairing steel sheet, L PinFor the length of pin b with choose transition fit as the fit dimension tolerance of hole and pin b;
Step 5, the friction pair material characteristic that obtains according to step 1, the physical dimension characteristic, supporting construction, loading characteristics and measuring point distribute and the parameters such as size is set up the three-dimensional simulation model of friction pair and loading structure thereof, and concrete grammar is:
In ANSYS or ABQUS according to the supporting construction of friction pair, dimensional requirements etc. are set up three-dimensional model, give three-dimensional model material cell attribute according to the material properties of friction pair, load according to magnitude of load according to the loading structure characteristics, obtain the stable state the results, choose the value of stress and strain of the Nodes of antithesis dish surface in contact, as the result of calculation of three-dimensional artificial.The foundation of model and the analysis of finite element are the approximate ranges for the pressure distribution of obtaining the friction pair surface in contact, for the selection of follow-up foil gauge provides preliminary foundation.
Step 6, carry out the FEM Numerical Simulation of multidimensional pressure load from three-dimensional model, tentatively determine the ess-strain scope of friction pair surface in contact.The selected point of ess-strain is at the Nodes of unit, and along radial distribution, the data area of obtaining is the scope of pressure.And determine the major parameter of the resistance strain gage that is suitable for this friction structure according to this scope, the initial resistance that comprises foil gauge, sensitivity coefficient and strain limit, choose suitable foil gauge according to parameter, when the specification of selection foil gauge and form, it should be noted that the stress state of material character and the member of member.What measure because of foil gauge is mean strain, when the component stress variation range is larger, generally selects small tenon apart from foil gauge.(concrete system of selection sees foil gauge for details selects relevant books).
Step 7, the resistance strain gage that is fit to is affixed on the flat side of pin, check whether the foil gauge resistance value is the initial resistance of resistance strain gage, if it is little that resistance shows with the initial resistance difference of resistance strain gage, the success of foil gauge paster is described, bridge circuit, B, D end is connected respectively at the wire that connection terminal 5 links to each other, and A, C end is connected to respectively external stabilization 5V voltage, guarantees that namely the voltage between A, the C end is stable 5V voltage.The computing formula of its circuit is:
U i = ( R 1 R 3 - R 2 R 4 ( R 1 + R 2 ) ( R 3 + R 4 ) ) U 0 Formula 1
If R is arranged 1R 3=R 2R 4E=0 then, this is the zeroing circuit of foil gauge, when resistance after its resistance value changes during at alteration of form, the change amount of the value of voltage is:
Δ U i = R 1 R 2 ( R 1 + R 2 ) 2 [ Δ R 1 R 1 - Δ R 2 R 2 + Δ R 3 R 3 - Δ R 4 R 4 ] Formula 2
Can obtain the change value of resistance by following formula, and and then obtain the value of dependent variable according to the resistance characteristic of resistance itself, and go out again the value of pressure by the friction pair material property calculation.Then pin is packed on the pairing steel sheet in the corresponding pin-and-hole, use the plug screw pretension, finish the assembling of antithesis sheet;
Step 8, the antithesis sheet that assembling is finished require its surface in contact is carried out secondary processing according to the manufacturability of friction pair on engineering, purpose is to reduce pre-buried pin to the impact of contact character of surface, then will be embedded with the antithesis sheet of pin and friction disc is installed to and carries out break-in on the friction wear testing machine, running-in time is not less than 30min, and running in speed is determined according to the operating mode rotating speed of living in of friction pair;
Step 9, the sufficient friction pair of break-in is loaded according to actual working conditions, loading environment can be the pressure test of static state, also can be dynamically pressure testing (what is called dynamically refers to frictional disk and antithesis dish relative sliding), when carrying out dynamically pressure testing, need add power up brush on the link circuit of foil gauge, in order to prevent the winding of return wire, on-load pressure is consistent with actual condition load, open the resistance-strain Acquisition Instrument, by voltage index gauge zeroing circuit, and the transmission of the signal by bridgt circuit, collection signal also obtains the stress-strain state of each measuring point of friction surface.The stress-strain measurement value of each measuring point has directly reflected the contact condition of friction pair surface in contact, the measured value of the local ess-strain that contact is larger is relatively large, otherwise contact inadequate place, the measured value less of ess-strain, the method can effectively be measured friction disc from the released state to the contact condition, again to measurement and the monitoring of the real-time pressure state of the sliding state that rubs.
Further specify implementation procedure of the present invention below in conjunction with specific embodiment.
Step 1, definite manufacturability requirement that needs the friction pair of measurement are such as agglomerated material requirement, processing technology requirement, comprising the flatness of surfaceness, Friction Disk Surface.Friction material is Cu base powder metallurgy agglomerated material, and choosing internal diameter is Ф 160mm, and external diameter is that the friction pair of Ф 200mm is as research object, the thickness of antithesis sheet is 10mm, and material is the 45# steel, and surface hardening is processed, surface processing technique is to roughly grind behind the finish turning, and roughness 0.8, flatness are 0.04.Material is 30CrMnSiA, and heat treatment characteristic is modulation, and hardness is HRC55-60.Scantling changes during for fear of secondary processing, reserves surplus in the steel disc process for last procedure grinding accordingly, and the thickness of antithesis sheet is 10.2mm.Hydraulic loaded, pressure limit is 0-20000N, working temperature is no more than 300K.
Step 2, determine distribution and the measuring point quantity of measurement point according to the characteristics of differentiated friction auxiliary structure.
The state that distributes in order to measure radial pressure is chosen measuring point diametrically, satisfies diametrically linear distribution such as the hypothesis contact, then chooses two measuring points at close internal-and external diameter place and can satisfy the measurement requirement.If the radial distribution of contact is complicated, then need to select a plurality of measuring points, the measuring point of choosing distributes as shown in Figure 2.
Step 3, determine diameter D and the length L of pin according to the requirement of precision, the diameter of pin has certain restriction, selects 30CrMnSiA material diameter D=4mm, length L=5mm.Surfaceness is 1.6, modified thermal treatment, HRC55-60.Synoptic diagram as shown in Figure 3, Fig. 4 is for just waiting shaft side figure.
Step 4, be 4mm in steel disc punching, aperture basic size, hole depth 5mm, tapping, screw thread be M4, by attacking line degree of depth L Spiral shell=L Sheet-L PinThe tapping degree of depth is 5mm as can be known.The fit dimension of hole and pin should be chosen for transition fit H7/k6, as shown in Figure 5, it is inner that a plug screw b pin c foil gauge all is positioned at the antithesis dish, antithesis sheet through hole is positioned at the unthreaded hole that is of pin position, be positioned at the threaded hole that is of plug screw position, plug screw plays the tightening effect to pin, and foil gauge is affixed on the flat side of pin.
Step 5, the friction pair material characteristic that obtains according to step 1, the physical dimension characteristic, supporting construction, loading characteristics etc. are set up the three-dimensional simulation model of friction pair and loading structure thereof, as shown in Figure 6.The boundary condition of model should be close with physical condition, determines the constraint condition of model according to supporting construction, according to operating mode (static friction, sliding friction etc.) determine the contact type of surface in contact, and the size of the selection of unit and load applying etc.
Step 6, three-dimensional model is carried out the finite element simulation of multidimensional pressure load, tentatively determine the ess-strain scope of friction pair surface in contact.The selected point of ess-strain is at the Nodes of unit, and along radial distribution, the data area of obtaining is the scope of pressure.Simulation result as shown in Figure 7, and is as shown in table 1 by getting a little, as can be known at the radially-arranged pressure of friction surface.
The node surface pressure result that table 1 radially distributes
Figure BDA00003567640200121
And determine the major parameter of the resistance strain gage that is suitable for this friction structure according to this scope, choose suitable foil gauge according to parameter, the classification of foil gauge is the paper tinsel formula, substrate is that glass fibre strengthens synthetic resin, sensitive grid length is selected 3mm, version is that AA Standard resistance is 350 Ω, and 80 ℃ of work maximum temperatures are for temperature self-compensation or elastic modulus self compensation.
Step 7, first foil gauge 2 that will be fit to are affixed on the flat side of pin; the paster process as shown in Figure 8; paster adopts 502 glue on the sole plane of point position and foil gauge; coat thin layer glue; pinch on the other hand the first foil gauge 2 and draw lead-in wire 3; axix of strain gauge alignment coordinates line; upper cover layer of polyethylene plastic sheeting 4 is as interlayer; with the length direction gently roll extrusion of finger at strainometer; extrudate piece bubble and unnecessary glue; until strainometer and measured object close adhesion are coated with lid layer anti-blushing agent 1 at last as protection on its surface.
Bridge circuit as shown in Figure 9, usually static strain is measured with twin-core multiply parallel lines.Before the welding lead, be connected to first the two ends of connection terminal 5 with universal electric meter, check whether resistance value is the initial resistance of resistance strain gage, prevention by the wiring multimeter is shown as 352 Ω, the success of foil gauge paster is described, check that wire does not open circuit, then stick the number label at the connection terminal two ends of each measuring point foil gauge, to show that differentiation causes mistake when avoiding measuring point many, use soldering that connection terminal is connected with wire, bridge circuit as shown in figure 10, B, the D end is connected respectively at the wire that connection terminal 5 links to each other, A, the C end is connected to respectively external stabilization 5V voltage, namely guarantees A, voltage between the C end is stable 5V voltage.
Step 8, pairing steel sheet that assembling is finished carry out the secondary grinding according to the manufacturing technique requirent of friction pair to its surface in contact, the surfaceness of pairing steel sheet is worked into 0.8, then will be embedded with the pairing steel sheet of pin and friction disc is installed to and carries out break-in on the MM6000 friction wear testing machine, starting outfit control rotating speed is 1500r/min, time is 30min, on-load pressure is 1MPa, and the cooling flow is 4ml/mm 2S.
Step 9, load according to actual working conditions, on-load pressure is: 0.886MPa, and zeroing circuit, the computing formula of zeroing circuit is:
U i = ( R 1 R 3 - R 2 R 4 ( R 1 + R 2 ) ( R 3 + R 4 ) ) U 0 Formula 1
If R is arranged 1R 3=R 2R 4E=0 then, this is the zeroing circuit of foil gauge, when resistance after its resistance value changes during at alteration of form, the change amount of the value of voltage is:
Δ U i = R 1 R 2 ( R 1 + R 2 ) 2 [ Δ R 1 R 1 - Δ R 2 R 2 + Δ R 3 R 3 - Δ R 4 R 4 ] Formula 2
Finish measurement to pressure state by the variation of measuring voltage value, by electric wire strain gauge magnitude of voltage is transferred to the signal processing and analysis device, by the signal processing and analysis system corresponding change in voltage is converted into strain, and calculates stress by elasticity modulus of materials E.The data result curve that obtains as shown in figure 11, increase with radius, the measured stress value of measuring point is on a declining curve, this is that loading structure is for the impact of pressure contact state, for the minor fluctuations in the curve, then embodied because the impact of surface processing technique characteristics (roughness, flatness) causes.
Test by experiment as can be known the present invention and can effectively measure the quiet dynamic touch pressure of friction pair, experimental result has been carried out preliminary identification to simulation result, for the friction pair pressure boundary condition accurately obtain and dynamic design approach provides test to support.
The content that is not described in detail in the instructions of the present invention belongs to the known prior art of this area professional and technical personnel.

Claims (1)

1. one kind is used for the secondary contact dynamic measurement method of disk friction, it is characterized in that performing step is as follows:
Step 1, determine working condition under the friction pair duty and the loading structure characteristics of friction pair, obtain the physical dimension of friction pair, determine that according to the manufacturability requirement of the friction pair that will measure the roughness of friction pair surface in contact requires and the processing request of surface planarity;
Position distribution and measuring point quantity N rapid two, determine the measurement point on the friction pair antithesis sheet according to the physical dimension of the loading structure characteristics of analyzing the friction pair that obtains in the step 1 and friction pair;
Step 3, the Friction Disk Surface roughness and the flatness requirement that obtain according to the step 1 analysis require to determine diameter D and the length L of pin in conjunction with size, antithesis sheet thickness, foil gauge size and the measuring accuracy of friction pair surface in contact, and the method for determining is as follows:
Pin diameter D＜(R-r)/2, R is antithesis sheet external diameter, and r is antithesis sheet internal diameter; B/2＜L＜2B/3, B are antithesis sheet thickness, and the D that the friction surface contact friction of roughness 1.6 flatnesses 0.04 is selected should be greater than 12mm, and still minimum should be less than the width b of minimum strain sheet, and the diameter D scope of the pin of choosing is: 4-12mm; The pin of having determined diameter D and length L is embedded in the embedded hole to the steel disc that rubs;
The dimensioned pin of step 4, the pin that obtains according to step 3, and process a plane on the pin side face of cylinder, be used for pasting foil gauge, the size of processing plane should be greater than the size of foil gauge, beat the hole of pre-buried pin according to the D that has determined and L in the position of layouting of the required measured zone of antithesis sheet, tapping in the pin hole of antithesis sheet noncontact face, attacking the line degree of depth is B-L, chooses transition fit as the fit dimension tolerance of hole and pin;
Step 5, the friction pair material characteristic that obtains according to step 1, the physical dimension characteristic, the supporting construction characteristics, loading characteristics etc. are set up the three-dimensional simulation model of friction pair and loading structure thereof, three-dimensional model is carried out the finite element simulation of multi-direction pressure load, for the contact test is provided fundamental basis and the prediction of numerical range;
Step 6, determine the range of stress of friction pair surface in contact according to the simulation results of step 5, and select the resistance strain gage that is fit to according to this range of stress, its major parameter comprises the initial resistance of foil gauge, sensitivity coefficient and strain limit;
Step 7, choose and obtain suitable monitor strain sheet by step 6, foil gauge is affixed on the plane that pin processes in advance, check whether the foil gauge resistance value is the initial resistance of resistance strain gage, if it is little that resistance shows with the initial resistance difference of resistance strain gage, the success of foil gauge paster is described, bridge joint strain operation circuit, and pack on the antithesis sheet pin in the corresponding pin-and-hole and fix with the pretension screw;
Step 8, the pairing steel sheet that assembling is finished carry out secondary processing according to worker's property requirement of the friction pair production and processing of step 1 analysis acquisition to the friction pair surface in contact, friction pair is installed to carries out break-in on the friction wear testing machine, running-in time is not less than 30min, and running in speed is determined according to the operating mode rotating speed of living in of analyzing the friction pair that obtains in the step 1;
Step 9, the sufficient friction pair of break-in is carried out quiet dynamic load, connect the resistance-strain Acquisition Instrument, by voltage index gauge zeroing circuit, and the signal transmission by bridgt circuit, obtain the stress-strain state of each measuring point of pre-buried pin place friction surface.
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Publication number Priority date Publication date Assignee Title
CN103630275A (en) * 2013-11-20 2014-03-12 北京航空航天大学 Embedded measuring method for contact press of annular friction pair
CN103630275B (en) * 2013-11-20 2016-04-06 北京航空航天大学 A kind of for annular friction secondary contact embedded measurement method
CN104634676A (en) * 2015-02-13 2015-05-20 中国北方车辆研究所 Method for controlling dynamic test load of friction plate and system for realizing method
CN104634676B (en) * 2015-02-13 2017-09-01 中国北方车辆研究所 A kind of system for controlling the method for friction plate dynamic test load and realizing this method
CN105758564A (en) * 2016-04-28 2016-07-13 辽宁科技学院 Blind hole surface mounting measuring method used for shear stress of conical friction pair
CN105953953A (en) * 2016-04-28 2016-09-21 辽宁科技学院 Pin embedded measuring method for tapered friction pair contact pressure
CN105973508A (en) * 2016-04-28 2016-09-28 辽宁科技学院 Resistance strain gauge bonding and calibration method capable of measuring contact pressure of disc friction pair
CN105973737A (en) * 2016-04-28 2016-09-28 辽宁科技学院 Method for obtaining wearing capacity of friction plate
CN114483817A (en) * 2021-11-23 2022-05-13 株洲时代新材料科技股份有限公司 Torque limiter and assembling method thereof
CN114483817B (en) * 2021-11-23 2024-02-27 株洲时代新材料科技股份有限公司 Torque limiter and assembly method thereof

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