JB/T 9837-1999 Calculation method for load-bearing capacity of tractor cylindrical gears
Some standard content:
ICS 65.060.10
Machinery Industry Standard of the People's Republic of China
BF9837—1999
Calculation methods of load capacity of cylindrical gears for tractors1999-08-06 Issued
National Bureau of Machinery Industry
Implementation on 2000-01-01
JR/T0837—1999
This standard is a revision of ZBT63M989 "Calculation methods of load capacity of cylindrical gears for tractors". Compared with 2BT63009-89, this standard has some changes in the following major technical contents: The nominal load of a pair of calculated gears is coordinated with the relevant standards and expressed in formulas. This standard replaces ZBT63009-89 from the date of implementation. Appendix A of this standard is a reminder of the appendix.
This standard is issued by the National Technical Committee for Standardization of Tractors and is under the jurisdiction of the National Technical Committee for Standardization of Tractors. The originator of this standard is Luoyang Tractor Research Institute. The main drafters of this standard are Sun Weigong and Ding Ruixi. 1 Scope
Machinery Industry Standard of the People's Republic of China
Calculation method of load capacity of cylindrical gears for tractors This standard specifies the calibration method of the contact film and temperature of the tooth surface of tractor gears. JA/T9837-1999
Replacement ZDT63009B9
Not applicable to the internal and external meshing spur and helical involute cylindrical gears of tractors that meet GDT1356 and other non-20* angles. The inner gear should meet the requirements of JD/T5615. The left standard is also applicable to the gears of vehicle transmissions similar to tractors. 2 Reference standards
The following standards contain provisions that constitute the correct provisions by reference in this standard. When the sub-standard version is released, the versions shown are valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T13561988
Gear basic technology for disconnected line hanging gear
GBT29791991
Agricultural tire series
GD/T3480—1997
Calculation method for cutting capacity of inner system of new disconnected line hanging rod JB/T5615—[991
3 Codes and terms
Technical conditions for inner wheel of tractor transmission
This standard adopts the codes and terms listed in Table 1. Table 1
Inner wheel center distance
Terminology
Tooth stiffness (average value of total stiffness of single tooth) Single row tooth length (--the maximum degree of unit tooth length of the gear) Thread diameter of main and large wheels
Tooth root diameter of small and large wheels
Base diameter of small and large wheels
Root diameter of small and large wheels
Tension model (Shimo Hall)
Distance from the center of the tool tip to the symmetry line of the tool tooth||tt ||Normal axial force for base circle in normal plane
Nominal axial force for base circle in normal plane
Initial limit gear error
Approved by the National Bureau of Machinery Industry on 193-08-06
N/(mmμm)
Ni(numμm)
Implemented on 2000-01-01
Basic pitch limit deviation
JB/T9837—1999
Table 1 (System)
Term or educational text
Load acting on a single pair of teeth in the outer point of the engagement area of the bending force bone 77 Its basic density of each tooth item height
Make the fat coefficient
Variable elasticity state calculation to do the odd distribution number
Bending load calculation coefficientConnection sensitivity calculationTooth load distribution cumulative variable contact strength calculationTooth load distribution system effect single gear uniform system excitation
dynamic effect system effect
Full-directional purchase
Reduced area carbon coating
Wheel filling large area arithmetic mean difference
Drive or wheel half light
Variable bending strength What is the symbol of the system teaching
Li two strength minimum safety factor
Report strength calculation safety system effect
Connect The minimum safety factor of the strong and simple
tooth thickness of the dangerous surface F
small, the nominal torque of the wheel
the rated torque of the engine
the torque of the tractor wheel belt (avoidance belt)
speed insect, divided into the skin to read the peripheral speed
unit out of the width and flat groove load
variation coefficient
oxygen substitution is used for the tooth shape system when the external point of the single-pair engagement area is the relative tooth root table condition system effect
the stress stop system effect number and the test gear stress coefficient, F-2
variation strength quality calculation again
relative tooth root angle frequency effect
select the net running-in
step running amount||tt| |Single tooth coupling type
node area European coefficient
Tung oil integration
Symptom coefficient
Descending system effect
4 Basic formula
JB9837—1999
Table (complete)
Technical proof or meaning
The strong quality of the frequency family system used
Contact selection coefficient
Small, large number of teeth
Small, large number of teeth of the inclined wheel
The normal speed at the external point of the single pair of teeth coupling area is the normal speed at the external point of the single pair of teeth area
The end face pressure angle at the external point of the single pair of teeth coupling area is the national output angle||t t||Surface pressure angle
Surface contact
Machine-shaped
Surface contact
Basic screw
Main content of surface
: longitudinal overlap
Total fit
Lubricating oil movement viscosity
Basic internal gear mesh national diameter
Gear root fillet radius at the critical surface
Calculate the long bending stress
And the basic strength of the root
Allowable gear bearing force
Calculate the connection force
Calculate the actual connection force
Test limit of the connection
4.1 Surface contact strength
4. 1.1 Calculate the contact point force CH according to formula (1): CHZuZZeZ,
4.1.2 Calculate the allowable contact stress hpCFHn according to formula (2): hpCFHn=
Clim.21 2, Z.
(ni,ral
to)rad
JB/T9837-1999
4.1.3 Verify the load capacity according to formula (3) and formula (4): TSH
4.2 Tooth root bending strength (calculated separately for small gear and large gear) 4.2.1 Calculate the root bending stress FGE
YYY.KKKe
4.2.2 Calculate the allowable tooth root stress {F: CEe
4.2.3 Verify the load capacity according to formula (7) and formula (8): Orlin Ygr Ye mit 5. Determination of general calculation data and coefficients 5. The nominal torque T and the nominal stroke force F are converted from the rated torque of the engine to the torque on the calculation gear. And according to the tractor tire (warm belt) attached torque Work converted to the calculation gear torque, in which the smaller of the two is taken as the nominal torque Work formula is shown in formula (9) formula (11): 1, = 2Gra?
Tha-T, iha Wh.
iee er
--(10)
Where: G each drive tire load-bearing capacity (take the load-bearing capacity when the tire pressure is 0.1MPa, taken in GB/T2979) or the vertical force of each side belt on the ground, N: driving wheel dynamic radius, the nominal size of the tire multiplied by 0.95: crawler track according to the driving wheel radius: 11: attachment coefficient, wheeled tractors take 0.65: belt tractors take 1.0. - is the transmission ratio from the engine and from the driving wheel to the calculation wheel; "- is the transmission efficiency from the engine and from the driving wheel to the calculation wheel, respectively. The transmission efficiency of the gears uses the following empirical values: 0.98 for the main gear, 0.97 for the side chain gear, and 0.96. For four-wheel drive tractors, the ratio between the rated engine torque and the front and rear drive wheel load capacity is used to calculate the front and rear drive wheel torques T, ... When calculating the gear of the computer plow tire, the nominal torque is converted according to the rated torque of the engine; when calculating the gear of the power output shaft, the nominal torque is converted according to B0% of the rated torque of the engine. The nominal torque can be calculated according to formula (14): Where: z--the number of teeth of the gear being calculated. 5.2 Service factor K
R=2000×7
The service factor is a factor that considers the influence of power shortage caused by external factors of meshing. The service factor should be determined by actual load measurement or comprehensive system analysis [see the attached document for instructions]. When the above conditions cannot be met, you can refer to Table 2 for selection. Table 2 is determined by the results of the load measurement of the tractor. When calculating the gear of the planetary mechanism, the influence of uneven load distribution should be considered. The service factor should be multiplied by the planetary gear load distribution coefficient K.-1.05~1.1; the upper limit value is taken for those with low accuracy of the planetary carrier shaft hole distance. Table 2||t t||Puller wheel type
Agricultural wheeled tractor transmission system
Agricultural waist tractor transmission system
Kai Pai transmission system
Power output shaft gear gun (bin pinion)
5.3Dynamic coefficient K
1.20-1.30
1.20~1.30
1.8D-2.00
Dynamic load coefficient is to consider the meshing operation The coefficient of the influence of the internal incident dynamic load. It is defined as the ratio of the maximum force when the actual gear is engaged to the force generated by the pure external load. The gear transmission structure, size, rotation, wheel linearity, etc. of tractors and similar vehicles do not vary greatly, and the manufacturing accuracy is between 79 levels, most of which are %. According to the calculation of the dynamic load coefficient of some existing tractors and similar vehicles, the dynamic load coefficient variation range is not large, and it can generally be taken as K-1.03-1.06. 5.4 Tooth load distribution coefficient KHa, Kpg
The tooth load distribution coefficient is a coefficient that takes into account the uneven distribution of tooth width load. According to the specific situation of the tractor, the ratio of tooth width to module is generally in the range of 5-9. Calculate the tooth load distribution coefficient Kag, Ks according to formula (15) or formula (16): C, (Fa-Yg)
Kg=()Nr
Where: F=f.+A:
JB/T9837--1999
The meshing error component caused by the work and installation errors, m. According to the manufacturing conditions of the heat exchanger gear, the actual gear is close to 3/4 of the tooth tolerance, so it is taken as =0.75Fe, F. is the tooth tolerance, μm: the meshing tooth error component caused by the comprehensive deformation, μm, for the simply supported support, a=25F: for the total arm support, a=F is taken, and the one with lower structural stiffness is -(1.0-2.0)F. :rg-specific running-in, μmrg=0.15Fa6W-EK
C,-(0.75 +。+0.25) C;
C*=14N/(mmμm):
(5/A)*
N-index: N.
1+(0/)+()
5.5 Tooth load distribution coefficient KEa, Kr
The tooth load distribution coefficient is the response coefficient to the uneven load distribution between gear teeth when considering running-in. For spur gears:
KHa=K,=1
For helical gears, when the total contact degree e, reaches 2: s,
KHu =Kra =
(0.9+0.4x
When the total contact degree center>2:
KHu - Kyu + 0.9+ 0.4,
2(6, -1)
c,rs -r)
F, KAK KHg ?
G,(fr-ra)
FK, K, HnaIh
·(19)
In the formula: a basic pitch difference, μm: usually taken from the value of the wheel, when there is appropriate rim change, the tooth run-in is calculated as half of the limit deviation. -.
Total contact, \s.
Id.-d,+ya,-dw'y-a'sina?
Note: "" is used for external contact, "+" is used for dry state bsing
If the calculated value K.
Measure FHE-
If the calculated value is K. If the car is 1, then take K;
If the calculated value k8, then take K.
If the calculated value r, then double K. -
6 Calculation of tooth surface contact degree used in the system
6.1 Node area coefficient ZL
JB/T9837—1999
North point This area system is to consider the effect of the tooth sequence curvature at the node on the contact force, and convert the tangential force of the density network into the coefficient of the normal force on the node network.
2cosgcasm
cosa,sina
In: arctan(lancos)
g,=arctan (Lan gcas a,3:
inv@, =invz, +
Note: "、" are used for external reference, "" is used for internal coupling x, x; small and large gear face radial displacement coefficient. 6.2 Single tooth coupling coefficient 2
The single tooth coupling coefficient is the coefficient that converts the contact stress at the node engagement to the contact stress at the boundary point of the small gear single internal coupling area.
The overlap of tractor gears is generally less than 2, and most of them are within the range of 1.2-1.6. Tooth surface The thinning point is the inner boundary point of the single chisel, and the contact stress at the inner boundary point of the single meshing of the pinion should be used as the calculation method. If only the contact stress at the inner boundary point needs to be calculated, take =1.02g
In the formula: [an,-lunt
antancosg
c..urccos
li,d.cos'BbzxZ.net
Number of teeth on the pinion plate:
Zcos B.cosp
tana'cos
Ylaneylana
PP——Small and large gear node curvature radius:\1.P——Small and large gear ratio radius at the inner boundary point of the single tooth meshing area of the pinion;, ",The normal pressure angle of the small and large gears at the inner boundary point of the single tooth meshing area of the small gear: e
When the gear tooth circle is calculated, the force angle;
,d.—Equivalent gear base 6.7 Elastic coefficient Z
The elastic coefficient is a coefficient used to consider the influence of the elastic modulus and Poisson's ratio of the inner gear material on the contact stress. Ze
Where: E:, E is the elastic modulus of different material groups 1
For steel gear pairs, take E-206×10°MPa, 4=0.3, then 2-189.8MPm*. .{21)
JB/T 983T—999
For steel gear pairs, take E=173×10'MPa, 4=0.3, then Z-181.4MPa% 6.4 Overlap coefficient Z
The overlap coefficient is a coefficient used to consider the influence of overlap on contact stress. For the real gear of the trolley, since the inner boundary point of the single pair of teeth meshing area has been used as the calculation point of the contact stress, and the total load is used as the calculation load, the following is taken: z.-1.0
For helical gears, when the weave direction overlap is: when g:
6.5 Helix angle coefficient Za
The helix angle coefficient is a coefficient used to consider the influence of the probe angle on the contact stress, Z:ycosp
6.6 The contact stress calculation limit min (23)
refers to the limit stress of the gear of the material after long-term continuous repeated load (5×10° times) and failure. F is the specified value. TH-It is best to determine it by making a PSW curve from the gear endurance test. If there is no PSN curve available, the limit of the inner boundary point of the single tooth engagement for 20CrMnTi, 25MnTiB and similar materials with a spring force of more than 56HRC should be mm*1650-1750MPa. For steel with a surface hardness of 250-300HB, ckLm=600-700MPa can be taken. For ball castings of other hardness, 90% of rL of the same hardness can be taken as its limit stress. 6.7 The influence of the lubricating oil film on the contact strength coefficients 2., Z., 7. and the tooth surface contact intensity of the test gear under standard test conditions are compared. The main factors affecting the state of the oil film between the contact surfaces are: lubricating oil viscosity - use the full lubricant coefficient; working line speed - use the speed coefficient Z.; surface roughness is measured by the roughness coefficient Z. 6.7. Lubricating oil coefficient ZL
2. =0.91-
load Z, =0.91+
In the formula: 5014D
(1.2+80/v.))
(1.2 +134/p)3
-The kinematic viscosity of the lubricant at 50℃, 40℃, mm9, 6.7.2 Speed coefficient7
Zy0.93↓
(0.8+32/V)*5
Line speed of the wheel indexing net 1, m/ss
In the formula:
6.7.3 Needle fabric roughness coefficient Zu
JB/T9837—1999
Where: R, R,-The technical average deviation of the tooth surface of small and large gears,;- Gear center ratio: mme
6.8 Minimum safety factor of contact strength Smm(30)
The strength of the gear calculated by the price is often adjusted by the safety factor, but it does not reflect the reliability level. When the reliability theory has been used for mechanical design, it will not directly treat the various design parameters of the gear as random variables. At present, the system is not yet fully understood. Therefore, this standard will take the design parameters as fixed values, use the safety factor and allowable stress as the temperature judgment, and link the safety factor with the reliability requirements.
Based on the test, the minimum safety factor value is shown in Table 3. Table 3
1. General gear
The various coefficients used for the cross-bending strength of the gear teeth
T.1 External gear tooth shape coefficient
The tooth shape coefficient is a coefficient used to consider the influence of the tooth shape on the nominal bending stress. For tractor gears with a precision of -9, the maximum root stress occurs at the external point of the single tooth coupling area under load, so this standard does not use the point outside as the load action point for calculation. The tangent point of the tangent lines (Figure 1) on the left and right sides of the root of the tooth is used as the bending stress calculation point. The tooth form coefficient of the external gear can be determined by formula (31): hs
Formula (31) is applicable to any involute spur gear and helical gear. The tooth form coefficient of the helical gear is determined by the normal direction, that is, the equivalent gear Z is calculated. The tooth form coefficients of the large and small gears are determined separately. b/oesp
Figure calculates the bending stress of the gear tooth normal section and JR/T Ming 37-1999
The shear load angle varies with different shape angles (or similar shape angles and displacement numerators and load positions), and can be calculated according to the formula ():
A,3(47+1.57
Where: a similar tooth shape angle, rad;
a,eroxos
Tooth height coefficient:
clearance coefficient;
z, similar gear tooth number, 2-20.
.-Normal force angle of external point a.=arctan(tanαacoae).B,=arctan(d,tangi d) 532
The standard is applicable to all teeth with protruding angles and without protruding angles, and is limited to: the tangent point of the nine-line and the tooth angle should be on the transition curve formed by the rounded corners of the blade! . The basic tooth size of the tool is shown in Figure 2, and all the formulas for calculating the external shape coefficient are listed in Table 4. Figure 2 shows the basic tooth size
The starting height of the protruding angle of the tool tooth
The distance from the tool to the tool
The basic angle
The calculation method
smgcosa
is the tool without protruding angle
Take more than 0
When there is no protruding angle
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.