The invention content is as follows:
the invention aims to provide a method for evaluating the service life of a metallurgical crane reducer gear with optimized parameters.
The invention provides a method for evaluating the service life of a gear of a reducer of a metallurgical crane by optimizing parameters, which comprises the following steps:
(1) and constructing a tooth profile wear amount calculation formula based on an Archard (Archard) wear calculation model.
(2) And the transmission gears at the front and rear stages of the speed reducer ensure that the total transmission ratio is unchanged from the number of teeth of the driving wheel at each stage, the transmission ratio at each stage is adjusted within a reasonable range of the number of teeth, and the tooth profile abrasion loss and the whole service life are calculated in sequence.
(3) Aiming at the same-stage gear in the speed reducer, under the condition of ensuring that the transmission center distance is not changed, the modulus and the number of teeth of two wheels are adjusted, the tooth profile abrasion loss is calculated, and the change trend of the tooth profile abrasion loss is observed.
(4) The modification coefficient is introduced to achieve the purposes of reducing the tooth profile abrasion loss and prolonging the service life.
The method for constructing the tooth profile wear amount calculation formula based on the Archimedes wear calculation model in the step (1) comprises the following steps:
(1) due to the relative sliding speed existing between tooth profiles, a sliding coefficient expression is constructed according to a gear meshing schematic diagram:
in the formula: lambda [ alpha ]1Sliding coefficient at meshing point K on the driving wheel, λ2Slip coefficient at meshing point K on the driven wheel, i-transmission ratio, α -meshing angle, αk1-pressure angle of the engagement point K on the driving wheel;
(2) according to the geometrical relationship in the gear meshing principle diagram, the pressure angle range at the meshing point is calculated:
in the formula: r is
1,r
2Is the radius of two wheels,
is the crest factor, m is the gear module, α
k2The pressure angle of the engagement point K on the driven wheel.
(3) Calculating the tooth thickness at any point on the tooth profile:
r
K,s
K,α
Kand theta
KThe radius, tooth thickness, pressure angle and spread angle of any circle,
is s is
KThe subtended central angle.
Wherein theta is tan α - α and thetaK=tanαK-αK
(4) and (3) calculating the contact ratio: epsilona=[z1(tanαa1-tanα)+z2(tanαa2-tanα)]/2π
In the formula αa1=cos-1(rb1/ra1),αa2=cos-1(rb2/ra2)
(5) Calculating the contact half width:
in the formula: t-input torque, μ
1,μ
2Poisson ratio of two rounds of material, E
1,E
2-the modulus of elasticity of the material of the two wheels,
-the tooth width factor;
(6) calculating the wear rate:
in the formula: i ish1,Ih2Wear rate of driving and driven wheels, k1,k2Two wheels wear factor, n1,n2-the rotational speed of both wheels;
(7) calculating tooth profile abrasion loss: h isI=2aλntεaIh。
Guarantee total drive ratio and every level action wheel number of teeth unchangeable, adjust every level drive ratio in reasonable number of teeth within range, calculate flank profile wearing and tearing volume and whole life-span in proper order and include following step:
(1) set rotational speed n1A torque value T;
(2) setting allowable tooth surface wear: in the lifting structure, the abrasion loss of the gear tooth profile on the first shaft is not more than 10% of the original tooth thickness, and the abrasion loss of the gear tooth profile on the other shafts is not more than 20% of the original tooth thickness. When the abrasion loss reaches the set value, the gear reaches the service life;
(3) set appropriate iGeneral assembly=i1·i2,i1、i2The transmission ratios of the high-speed gear and the low-speed gear of the speed reducer are respectively; z1,Z2Number of teeth of high-speed step pinions, Z3,Z4The number of teeth of the low-speed big and small gears is i1=Z2/Z1,i2=Z4/Z3;
(4) Holding Z1,Z3And iGeneral assemblyUnchanged by changing i appropriately1To obtain a corresponding Z2,Z4And i2。
(5) Calculate each i1And (4) recording and observing the change trend of the service life of the high-speed gear and the low-speed gear corresponding to the value.
The method for calculating the tooth profile abrasion loss comprises the following steps of:
(1) setting the modulus of high-speed stage as m1,Z1,Z2The number of teeth of the high-speed big gear and the high-speed small gear;
(2) change modulus to miTo obtain a correspondence Z1i,Z2iGuarantee mi(Z1i+Z2i)=m1(Z1+Z2);
(3) Calculate each m in turniAnd recording and observing the change trend of the corresponding wear life.
The method for introducing the deflection coefficient comprises the following steps:
(1) according to the gear meshing diagram, a sliding coefficient expression is derived through a geometrical relation:
(2) setting of lambda1max=max(λ1),λ2max=max(λ2),u=λ1max/λ2max;
(3) The coefficient of variation is x, e ═ mx, i.e. when λ1And λ2In the image N2N1When the gear is translated to the right by a distance of e (the rightward translation is positive deflection, and the leftward translation is negative deflection), the value of u is close to 1, and at this time, the two gears are considered to be in an approximate equal wear state.
The invention realizes the reduction of the wear rate of a single gear, the reduction of the tooth profile wear difference between the driving wheel and the driven wheel of the same gear and gears of different stages by adjusting the basic parameters of the gears, and the aims of prolonging the service life of the gears and the equal wear among the gears are fulfilled.
Description of the drawings:
FIG. 1 is one of the tooth profile engagement illustrations of the present invention;
FIG. 2 is a second schematic view of the inventive tooth profile engagement;
FIG. 3 is a schematic illustration of the calculated tooth thickness of the present invention;
FIG. 4 is a graph of slip coefficient versus pressure angle for the present invention;
FIG. 5 is a tooth thickness curve at any meshing point of the tooth surfaces of the present invention;
FIG. 6(a) is a schematic view showing the amount of wear at any meshing point of the tooth surfaces of the driving wheels according to the present invention;
FIG. 6(b) is a schematic view showing the amount of wear at any meshing point of the tooth surfaces of the driven wheel in the present invention;
FIG. 7 shows a diagram of the present invention iGeneral assemblyWear life of two-stage gear at 5.6 hours and i1A relation curve of the ratio;
FIG. 8 shows a diagram of the present invention iGeneral assemblyWear life of two-stage gear at 7.2 hours and i1A relation curve of the ratio;
FIG. 9 shows a diagram of the present invention iGeneral assemblyWear life of two-stage gear at 9.6 hours and i1A relation curve of the ratio;
FIG. 10 is a graph showing the relationship between the wear loss and the modulus after changing the parameters of the high-speed gear according to the present invention;
FIG. 11 is a graph showing the relationship between the wear loss and the modulus after changing the parameters of the intermediate gear in the present invention;
FIG. 12 is a graph showing the relationship between the wear loss and the modulus after changing the parameters for the low-speed gear according to the present invention;
FIG. 13 is a graph showing the relationship between the wear loss and the modulus after the parameters of the three-stage gear are changed;
FIG. 14 is a graph of the initial slip coefficient of the high speed stage gear of the present invention;
FIG. 15 is a graph of the initial slip coefficient of the low speed stage gear of the present invention;
FIG. 16 is a graph of the slip coefficient of a high speed gear after it has been indexed according to the present invention;
fig. 17 is a sliding coefficient curve of the low gear according to the present invention after being shifted.
The specific implementation mode is as follows:
the present invention will be described in detail below with reference to the accompanying drawings and examples.
Firstly, constructing a tooth profile abrasion amount calculation formula based on an Archimedes abrasion calculation model; secondly, for the front and rear two-stage transmission gears of the speed reducer, the total transmission ratio is ensured to be unchanged with the number of teeth of the driving wheel at each stage, the transmission ratio at each stage is adjusted within a reasonable range of the number of teeth, and the tooth profile abrasion loss and the whole service life are calculated in sequence; then, aiming at the same-stage gear in the reducer, under the condition of ensuring that the transmission center distance is not changed, adjusting the modulus and the number of teeth of two wheels, calculating the tooth profile abrasion loss, and observing the change trend of the tooth profile abrasion loss; finally, the modification coefficient is introduced, so that the purposes of reducing the tooth profile abrasion loss and prolonging the service life are achieved.
Preferably, a ZSC-400 vertical speed reducer is selected as an embodiment, a metallurgical crane speed reducer gear life evaluation method based on optimized parameters is carried out, and the original parameters of a three-stage involute straight toothed cylindrical gear are shown in the following table.
TABLE 1 initial parameters of the three-stage gear of the reducer
Parameter name
|
High speed stage
|
Intermediate stage
|
Low speed stage
|
Number of teeth Z
|
Z1=18,Z2=42
|
Z3=14,Z4=56
|
Z5=20,Z6=48
|
Modulus m
|
3
|
4
|
5
|
Normal pressure angle α (°)
|
20
|
20
|
20
|
Normal tooth crest height coefficient h a * |
1
|
1
|
1
|
Coefficient of normal clearance* |
0.25
|
0.25
|
0.25
|
Theoretical center distance a (mm)
|
90
|
140
|
170
|
Tooth width b (mm)
|
30
|
40
|
50
|
Modulus of elasticity E (GPa)
|
E1=210,E2=206
|
E1=210,E2=206
|
E1=210,E2=206
|
Poisson ratio upsilon
|
0.3
|
0.3
|
0.3 |
In order to perform the following calculation, the above basic parameters are used to calculate the intermediate quantities of the gear, such as the reference circle, the base circle, the addendum circle, the dedendum circle, and the like, and the specific calculation process is as shown in the following formula:
radius of reference circle: r is1=Z1m1/2=27mm,r2=Z2m1/2=63mm,r3=Z3m2/2=28mm,r4=Z4m2/2=112mm,r5=Z5m3/2=50mm,r6=Z6m3/2=120mm
Radius of base circle: r isb1=r1cos(α)=25.372mm,rb2=r2cos(α)=59.201mm,rb3=r3cos(α)=26.311mm,rb4=r4cos(α)=105.246mm,rb5=r5cos(α)=46.985mm,rb6=r6cos(α)=112.763mm
Pressure angle range at meshing point on each gear tooth profile:
high speed stage gear αk1∈(5.922°,32.249°),αk2∈(14.943°,26.235°);
Intermediate stage gear αk1∈(3.220°,32.252°),αk2∈(15.744°,22.866°);
Low gear αk1∈(5.112°,31.321°),αk2∈(14.687°,25.564°)。
The result of the contact ratio calculation is: epsilon1=1.626,ε2=1.618,ε3=1.543。
Setting input power to 4kw, and rotation speed n1720r/min, and 51000N mm of input torque.
Selecting high-speed stage and low-speed stage gears of a ZSC-400 vertical speed reducer as research objects of step two, and setting a total transmission ratio to be iGeneral 1=5.6,iGeneral 2=7.2,iTotal 3The calculations were performed sequentially for the three cases of 9.6.
In calculating step (2), the total transmission ratio i is ensured in each caseGeneral assemblyAnd two stages of driving wheels with constant number of teeth, Z1=18,Z 320, independent variable is i1With a dependent variable of i2,Z2,Z4. The calculation process can be divided into the following steps:
step A: get iGeneral assembly5.6 with i1Making changes in the life of the two-stage gear and i1The occupancy relationship curve is shown in fig. 7.
And B: get iGeneral assembly7.2 with i1Making changes in the life of the two-stage gear and i1The occupancy relationship curve is shown in fig. 8.
And C: get iGeneral assembly9.6 with i1Making changes in the life of the two-stage gear and i1The occupancy relationship curve is shown in fig. 9.
The change trends of the two curves in the three graphs are contrastively analyzed, and a proper transmission ratio formula is selected to achieve the purposes of prolonging the service life of the gear and enabling the service lives of the gears of different stages to be close to each other.
And (4) regarding the step (3), selecting a three-level gear of the ZSC-400 vertical speed reducer as a research object, ensuring that the center distance is constant, wherein the independent variable is the modulus m, and the dependent variable is the tooth number of the two gears. The calculation process is divided into the following steps.
Step A: for high speed gears, the center distance a is maintained1Constant at 90mm, taking multiple values for modulus m to obtain corresponding Z1,Z2The life of the gear is calculated in turn, and the corresponding s ═ max (h)2)/max(h1) The calculation result, which is the ratio of the maximum wear amount of the driven wheel tooth profile to the maximum wear amount of the driving wheel tooth profile, is shown in table 2.
TABLE 2 calculated values of the life of the high-speed gears with different moduli
Modulus m
|
Number of teeth of driving gear Z1 |
Number of driven gear teeth Z2 |
Life t/(h)
|
Wear loss ratio s
|
2.4
|
23
|
52
|
13130
|
0.1813
|
2.5
|
22
|
50
|
11580
|
0.1648
|
2.6
|
21
|
48
|
10040
|
0.1487
|
2.7
|
20
|
47
|
8760
|
0.1222
|
2.9
|
19
|
43
|
7400
|
0.1256
|
3.0
|
18
|
42
|
6120
|
0.0989 |
The data in the table are fitted to a curve as presented in fig. 10.
And B: for intermediate stage gears, the center distance a is maintained2Constant 140mm, taking multiple values for modulus m, to obtain the corresponding Z1,Z2The life of the gear is calculated in turn, and the corresponding s ═ max (h)2)/max(h1) The calculation result, which is the ratio of the maximum wear amount of the driven wheel tooth profile to the maximum wear amount of the driving wheel tooth profile, is shown in table 3.
TABLE 3 calculated values of the service life of the intermediate gear with different moduli
Modulus m
|
Number of teeth of driving gear Z1 |
Number of driven gear teeth Z2 |
Life t/(h)
|
Wear loss ratio s
|
3.0
|
19
|
74
|
54790
|
0.0313
|
3.1
|
18
|
72
|
43960
|
0.0247
|
3.3
|
17
|
68
|
35280
|
0.0207
|
3.5
|
16
|
64
|
26620
|
0.0167
|
3.7
|
15
|
61
|
18750
|
0.0119
|
4.0
|
14
|
56
|
11660
|
0.0084 |
The data in the table are fitted to a curve as presented in fig. 11.
And C: for intermediate stage gears, the center distance a is maintained2Constant 170mm, taking multiple values for modulus m, to obtain the corresponding Z1,Z2The life of the gear is calculated in turn, and the corresponding s ═ max (h)2)/max(h1) The calculation result, which is the ratio of the maximum wear amount of the driven wheel tooth profile to the maximum wear amount of the driving wheel tooth profile, is shown in table 4.
TABLE 4 calculated values of life of low-speed gears with different modulus
Modulus m
|
Number of teeth of driving gear Z1 |
Number of driven gear teeth Z2 |
Life t/(h)
|
Wear loss ratio s
|
4.0
|
25
|
60
|
53290
|
0.0648
|
4.2
|
24
|
57
|
48240
|
0.0631
|
4.3
|
23
|
56
|
42730
|
0.0524
|
4.5
|
22
|
53
|
37170
|
0.0520
|
4.8
|
21
|
50
|
32830
|
0.0491
|
5.0
|
20
|
48
|
27510
|
0.0425 |
The data in the table are fitted to a curve as presented in fig. 12.
The three steps can reflect the rule that the gear life is increased along with the reduction of the modulus, which shows that the tooth profile abrasion loss is reduced.
It is stated that the tooth profile wear can be reduced by changing the number of teeth and the modulus.
For step (4), the tooth profile wear amount is reduced by introducing the modification coefficient, which can be divided into the following steps.
Step A: the tooth profile meshing schematic diagram 10 is obtained by taking high-speed gears and low-speed gears of a ZSC-400 vertical speed reducer as research objects, and a calculation formula of a sliding coefficient is converted into the following components through a geometrical relation:
the trend of the change can be judged more clearly according to the movement of the mesh point K, and the graphs are shown in fig. 14 and 15.
Calculated, in FIG. 11, the high speed stage gear λ1max=6.7907,λ2max=0.6550,μ1=λ1max/λ2max10.37, that is to say the wear of the tooth root of the pinion is 10.37 times that of the gearwheel;
in FIG. 12, the low gear λ1max=4.3463,λ2max=0.5508,μ1=λ1max/λ2max7.89, namely the wear degree of the tooth root part of the pinion is 7.89 times that of the gear wheel;
to achieve a close degree of wear of the two gears, i.e. a ratio μ close to 1, we wish to reduce λ1maxIs increased by2maxAnd therefore starting from the sliding coefficient calculation equations (11) and (12).
When the tooth profile meshing point K is closer to the point N1While, KN1Reduced length, KN2Increased length, λ1maxIs correspondingly smaller, λ2maxThe increase is made accordingly.
As can be seen from the tooth profile meshing schematic diagram, the transmission center distance is kept unchanged and overlappedOn the premise that the gear tooth depth is not less than 1.2, the radius r of the addendum circle of the large gear is gradually reduceda2Time, theoretical mesh point N2N1And the actual line of engagement B2B1All shift to the right, then1maxIs reduced therewith, and2maxwith this increase, the value of μ will be closer and closer to 1, achieving equal wear of both gears at the tooth root location.
Set the addendum circle radius r of the big geara2The reduction value of e, i.e. the gearwheel is a negative profile shifted gearwheel, the profile shift coefficient x2The pinion is a positive modified gear with modification coefficient x1=+e/m。
The Matlab programming calculation shows that under the condition of ensuring that the transmission ratio is not less than 1.2, the change value e of the radius of the top circle of the gear of the high-speed gear is 3.308, and the contact ratio epsilon is at the momenta1.290, pinion index x11.103, large gear deflection coefficient x2=-1.103;
The change value e of the radius of the addendum circle of the gear of the low-speed gear is 5.724, and the contact ratio epsilon isa1.301, pinion shift coefficient x11.145, large gear deflection coefficient x2=-1.145。
At this time, as shown in fig. 16 and 17, the slip coefficient curves of the pinion and the pinion are observed, and the maximum wear amounts on the tooth profiles of the driving wheel and the driven wheel are almost equal and both values are much smaller than those before the displacement in each gear stage. After the displacement treatment, the service lives of the driving wheel and the driven wheel are close to each other, the tooth profile abrasion loss can be reduced, and the service life is prolonged.