CN113221279B - Plunger-plunger hole friction pair low-wear surface profile design method - Google Patents
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- 238000000034 method Methods 0.000 title claims abstract description 15
- 238000005461 lubrication Methods 0.000 claims abstract description 17
- 230000015556 catabolic process Effects 0.000 claims abstract description 6
- 238000006731 degradation reaction Methods 0.000 claims abstract description 6
- 238000004364 calculation method Methods 0.000 claims abstract description 4
- 230000008569 process Effects 0.000 claims abstract description 3
- 238000005299 abrasion Methods 0.000 claims description 16
- 238000012938 design process Methods 0.000 claims description 2
- 239000011159 matrix material Substances 0.000 description 18
- 230000008859 change Effects 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- 108050006002 RNA polymerase sigma factor FliA Proteins 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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Abstract
The invention discloses a method for designing a low-wear surface profile of a plunger-plunger hole friction pair, which comprises the steps of firstly establishing a wear degradation model of the plunger-plunger hole friction pair, wherein the model consists of a force and moment balance equation of a plunger, a lubrication equation of the friction pair, an oil film thickness equation of the friction pair, a contact pressure equation of the friction pair and a wear depth variation calculation equation of a plunger hole, solving the wear degradation model to calculate to obtain a variation relation curve of the wear amount of the plunger hole along with time, finding a plunger hole wear profile line with the minimum variation rate of the wear amount of the plunger hole on the curve, and determining a key size parameter of the optimized lower-wear profile surface according to the wear profile line. The friction pair designed by the invention is convenient to process, and can effectively reduce the wear rate of the friction pair in the running-in stage and prolong the service life of the friction pair, particularly a heavy-load friction pair.
Description
Technical Field
The invention belongs to the field of structural optimization design of hydraulic pump/motor parts, and particularly relates to a service life prolonging design of a plunger-plunger hole friction pair.
Background
Plunger-type hydraulic pumps/motors are widely used in aerospace, industrial and mobile machinery as core components of hydraulic systems due to their high power density. Among them, the friction pair between the plunger and the plunger hole is one of the key friction pairs for realizing the function of the hydraulic pump/motor, and the excessive wear of the friction pair can deteriorate the oil inlet and outlet performance of the pump/motor, resulting in the failure of the pump/motor. Therefore, in order to improve the wear-reducing and wear-resisting performance of the plunger-plunger hole friction pair, the surface modification is often carried out on the plunger-plunger hole friction pair. However, in the wear-in stage (the initial stage of the friction pair work) with high wear rate, because the standard cylindrical surface profile of the friction pair cannot provide the optimal bearing and lubricating conditions, part of the surface modification layer of the friction pair is worn out in advance, and the long-term wear-resistant protection of the plunger-plunger hole friction pair is lost.
Disclosure of Invention
In view of the above analysis, the present invention aims to provide a method for designing a low-wear surface profile of a plunger-plunger hole friction pair, which realizes a design of prolonging the service life of the plunger-plunger hole friction pair by designing a simple and easily-processed pre-processed surface profile.
The purpose of the invention is realized by the following technical scheme: a design method for a low-wear surface profile of a plunger-plunger hole friction pair comprises the following steps:
step 1: and performing dynamic analysis on the plunger to obtain a force and moment balance equation of the plunger.
Step 2: and establishing a lubrication equation and an oil film thickness equation between the plunger piston-plunger piston hole friction pair according to an elastic fluid dynamic lubrication theory.
And step 3: and establishing a contact pressure equation of the contact area of the plunger and the plunger hole.
And 4, step 4: establishing a wear depth variation matrix of the plunger-plunger hole at different moments in the fluid lubrication, mixed lubrication and boundary lubrication states
And (4) calculating an equation.
And 5: carrying out abrasion degradation simulation on the hydraulic pump/motor, simultaneously solving the equations in the steps, and calculating an abrasion depth variation matrix at different moments
And 6: to abrasion depth variation matrix
And (5) solving the wear loss V at different moments through integration, and finding out a corresponding wear contour line when the change rate dV/dt of the wear loss is minimum.
And 7: the method for determining the axial width and the end face diameter of the chamfer comprises the following steps: dividing the abrasion contour line in the step 6 into two parts from the middle position in the axial direction, wherein the design processes of the two parts are the same; one part of the wear contour line is close to the end face of the plunger hole needing to be chamfered, and a diagonal line is formed through the maximum point of the wear contour line of the part; finding out the minimum angle of the oblique line to ensure that the abrasion contour line of the part just cannot exceed the oblique line, wherein the oblique line is superposed with the chamfered edge of the designed chamfer; the length of the edge of the chamfer angle along the axis of the plunger hole is the axial width of the chamfer angle, and the diameter of the edge of the chamfer angle on the end face of the plunger hole is the diameter of the end face of the chamfer angle.
Further, in step 1, the force balance equation is that the resultant force acting on the plunger is 0, and the moment balance equation is that the resultant moment acting on the plunger is 0, and the expression is as follows:
where Σ F represents the resultant force acting on the plunger, and Σ M represents the resultant moment acting on the plunger.
Further, the lubrication equation in step 2 is used for determining the oil film pressure of each point of the friction pair, and the expression is as follows:
wherein,
is a gradient operator, rho is a density matrix which represents the density of the lubricant at different positions of the friction pair,
is an oil film thickness matrix which represents the oil film thickness at different positions of the friction pair, vaveIs the average flow rate.
Further, the film thickness equation in the step 2 is used for determining an oil film thickness matrix
The expression is as follows:
where w is a wear depth matrix representing the current timeThe total wear depth of each position point of the friction pair is the fit clearance between the plunger and the plunger hole, e1And e3Eccentricity of the center of the plunger cross section at one end face of the plunger hole in the horizontal and vertical directions, e4And e2Eccentricity in the horizontal and vertical directions of the center of the plunger cross section at the other end face of the plunger hole, fhRepresenting the pass parameters w, c, e1、e2、e3、e4Computing
As a function of (c).
Further, the contact pressure equation in step 3 is used for calculating the contact pressure when the oil film between the plunger and the plunger hole is broken to generate contact, and the expression is as follows:
wherein p issIs a contact pressure matrix between the plunger and the plunger bore,
is a friction pair deformation matrix used for representing the deformation generated by the contact of the plunger and the plunger hole on each position point of the friction pair, fpIs shown to pass through
Calculating psIs measured as a function of (c).
Further, the abrasion depth variation matrix is calculated in the step 4
The expression of (a) is as follows:
wherein f iswIs represented by psAnd
computing
As a function of (c).
Further, the wear profile in step 6 is a curve formed by connecting a plane with the maximum wear depth at each axial position after the plunger hole side surface is unfolded.
Further, the invention has the advantages that: the size parameter of the low-wear surface profile designed by the invention is determined according to the wear profile when the wear amount changes minimally, so that the bearing lubrication performance of the friction pair in the running-in stage can be improved, and the advance failure of the wear-resistant modified layer on the surface of the friction pair is avoided, thereby leading the surface modified layer to achieve the purpose of long-acting wear-resistant protection; secondly, the low-wear surface profile designed by the invention is simple in structure and convenient to process.
Drawings
FIG. 1 is a flow chart of a plunger-plunger bore friction pair low wear surface profile design;
FIG. 2 is a schematic view of a force analysis of the plunger;
FIG. 3 is a schematic diagram of oil film thickness;
FIG. 4 is a graph of wear versus time;
FIG. 5 is a wear profile with a minimum rate of change in wear;
FIG. 6 is a schematic view of a low wear surface profile of a plunger-plunger bore friction pair;
fig. 7 is a side development view of a wear profile of a plunger bore when the rate of change in wear amount is minimized.
Detailed Description
The invention is further illustrated with reference to the accompanying drawings and specific examples.
As shown in FIG. 1, the invention provides a method for designing a low-wear surface profile of a plunger-plunger hole friction pair, which comprises the following specific design steps:
taking a plunger-plunger hole friction pair in an axial plunger pump as an example,
step 1: the dynamic analysis was performed on the plunger, which was subjected toTo an external force FeOil film force FoAnd the acting force F generated by the contact of the plunger and the plunger holesThe three forces form moments Me、Mo、MsAnd the three force vector sums sigma F and M are 0, and the three moment vector sums sigma M are 0, so that the force and moment balance equation of the plunger is obtained:
further, the external force F in step 1eIs the swash plate supporting force FsSHydraulic pressure FpFrictional force F of sliding shoefSAnd the friction force F between the plunger and the plunger holefCCentrifugal force F of plungercPlunger inertia force FiPlunger gravity FgThe vector sum of (1).
Step 2: assuming constant density of the lubricant, according to the elastohydrodynamic lubrication theory, establishing a lubrication equation between the plunger-plunger hole friction pair as follows:
wherein z isoRepresents ZoThe coordinates of the axes, as shown in FIG. 2, ZoThe shaft is along the axial direction of the plunger hole; thetaoRepresents winding ZoCircumferential angle of axis, passing through zoAnd thetaoDetermining the coordinates of any point of the friction pair; dCIs the diameter of plunger hole, mu is the viscosity of oil, h is the thickness of oil film at a certain point of friction pair, poIs the oil film pressure at a certain point of the friction pair, u is the linear velocity of the plunger relative to the plunger hole, omegapFor the plunger to wind around ZoThe spin speed of the shaft.
As shown in fig. 3, according to the geometric relationship, the oil film thickness equation is established as follows:
wherein,
is an oil film thickness matrix formed by the oil film thicknesses h at different positions of the friction pair, w is a wear loss matrix, c is a fit clearance between the plunger and the plunger hole, e1、e3Is the plunger cross section center X at one end face of the plunger holeO、YOEccentricity of e4、e2Is the plunger cross-section center X at the other end face of the plunger holeO、YOEccentricity of (L)CIs the length of the plunger hole, theta is a point on the oil film and YOThe angle between the axes.
And step 3: and establishing a contact pressure equation of the plunger and the plunger hole contact area.
Wherein p issIs a contact pressure matrix between the plunger and the plunger bore,
is a deformation matrix of friction pair, EPIs the modulus of elasticity of the plunger,Ec is the modulus of elasticity of the plunger bore, DPIs the diameter of the plunger, HCIs the radial wall thickness of the cylinder bore, Δ h being a matrix
An element of (1), RqPRoot mean square roughness, R, of the plunger surfaceqCRoot mean square roughness of the plunger bore surface.
And 4, step 4: establishing a wear depth variation matrix of different positions of the plunger-plunger hole in the states of fluid lubrication, mixed lubrication and boundary lubrication
The equation is calculated and the equation is calculated,
the calculation formula of any one element dw is as follows:
wherein k issIs the coefficient of adhesive wear, σsIs the yield strength of the plunger bore material, ds is the sliding distance between the plunger and the plunger bore, u is the sliding speed between the plunger and the plunger bore, τ is the delay time, Δ is the wavelength of the surface roughness, δ0Is the rough peak height of the plunger-plunger bore.
And 5: carrying out abrasion degradation simulation on the hydraulic pump/motor, simultaneously solving the equations in the steps, and calculating an abrasion depth variation matrix at different moments
Step 6: to abrasion depth variation matrix
The abrasion loss V at different moments is solved through integration, and the solving result is shown in figure 4; and finding the wear profile corresponding to the minimum dV/dt, namely the wear profile corresponding to the C point, as shown in FIG. 5.
And 7: designing easy-to-process chamfers at two ends of a plunger piston hole with serious abrasion, wherein the axial widths L of the two chamfersv、LsAnd end face diameter Dv、DsThe determination method comprises the following steps: as shown in fig. 6, the wear profile curve in step 6 is divided into left and right parts from the middle position in the axial direction; taking the left end abrasion contour line as an example, making a diagonal line passing through the maximum point B of the left end abrasion contour line; finding out the minimum inclination angle of the oblique line, so that the left end abrasion contour line just cannot exceed the oblique line, and the oblique line is the left chamfered edge; the length of the left chamfer along the axis of the plunger hole is the axial width L of the left chamfervThe diameter of the left chamfer edge on the end face of the plunger hole is the end face diameter D of the left chamferv(ii) a The right chamfer size is determined in the same way as the left chamfer.
Further, the wear profile in step 6 is a curve (as shown in fig. 5) formed by connecting the maximum wear depths at the axial positions in a plane after the side surfaces of the plunger hole are unfolded (as shown in fig. 7).
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (2)
1. A plunger piston-plunger piston hole friction pair low-wear surface profile design method is characterized in that: firstly, establishing a wear degradation model of a plunger-plunger hole friction pair, wherein the model consists of a force and moment balance equation of a plunger, a lubrication equation of the friction pair, an oil film thickness equation of the friction pair, a contact pressure equation of the friction pair and a wear depth variation calculation equation of a plunger hole, solving the wear degradation model to calculate to obtain a variation relation curve of the wear amount of the plunger hole along with time, finding a plunger hole wear contour line on the curve when the variation rate of the wear amount of the plunger hole is minimum, wherein the wear contour line is a curve formed by connecting the maximum wear depths at all axial positions in a plane after the side surface of the plunger hole is unfolded, designing easy-to-process chamfers at two ends of the plunger hole with serious wear, and determining key size parameters of the optimized lower-wear contour surface according to the wear contour line, and the specific process is as follows: dividing the abrasion contour line into two parts from the middle position of the axial direction, wherein the design processes of the two parts are the same; one part of the wear contour line is close to the end face of the plunger hole needing to be chamfered, and a diagonal line is formed through the maximum point of the wear contour line of the part; finding out the minimum angle of the oblique line to ensure that the abrasion contour line of the part just cannot exceed the oblique line, wherein the oblique line is superposed with the chamfered edge of the designed chamfer; the length of the edge of the chamfer along the axis of the plunger hole is the axial width of the chamfer, and the diameter of the chamfer on the end face of the plunger hole is the diameter of the end face of the chamfer.
2. The plunger-plunger hole friction pair low-wear surface profile design method according to claim 1, characterized in that the force and moment balance equation of the plunger represents that the vector sum of all forces acting on the plunger is 0, and the vector sum of all moments is 0; the lubrication equation and the oil film thickness equation of the friction pair are obtained through elastohydrodynamic lubrication analysis, the lubrication equation is used for solving oil film pressure distribution at each position of an oil film, and the oil film thickness equation is used for solving the oil film thickness at each position of the friction pair; the contact pressure equation of the friction pair is used for solving the contact pressure generated by the contact of the plunger and the plunger hole; and the calculation equation of the wear depth variation of the plunger hole is used for calculating the wear depth variation of any point of the friction pair at a certain moment.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH09189196A (en) * | 1996-01-10 | 1997-07-22 | Maeda Corp | Optimum-replacement time decision device for disc cutter in tunnel boring machine |
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| GB2535893A (en) * | 2013-11-08 | 2016-08-31 | Halliburton Energy Services Inc | Dynamic wear prediction for fixed cutter drill bits background |
| CN110332106A (en) * | 2019-07-23 | 2019-10-15 | 中国矿业大学 | A kind of crankshaft-plunger pair friction-wear test system and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH09189196A (en) * | 1996-01-10 | 1997-07-22 | Maeda Corp | Optimum-replacement time decision device for disc cutter in tunnel boring machine |
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