JB/T 8743-1998 Specification for involute spur gears for industrial and mining electric locomotives
Some standard content:
JB/T8743—1998
This standard is formulated in accordance with GB/T1.1-1993 Standardization Work Guidelines Unit 1 Part 1, GB/T1.22-1993 Standardization Work Guidelines Unit 2 Part 22, combined with GB3480-83 Involute Cylindrical Gear Load Capacity Calculation Method, GB10095-88 Involute Cylindrical Gear Accuracy, etc. The format and rules of the standard are made consistent or equivalent to those of the international standards as much as possible to meet the needs of international trade, technology and economic exchanges as soon as possible. The standard shall be implemented from November 1, 1998.
This standard is proposed and managed by Xiangtan Traction Electrical Equipment Research Institute. The drafting unit of this standard: Changzhou Industrial and Mining Electric Locomotive Factory. The drafters of this standard: Zhang Zhaorong, Rong Jiancai, Zhang Yi. 1 Scope
Machinery Industry Standard of the People's Republic of China
Specifications of involute straight and cylindricalgcars for mining & industrial electric locomotiveThis standard specifies the technical requirements, sampling and inspection of involute straight and cylindricalgcars for mining & industrial electric locomotive. This standard is applicable to various types of involute straight and cylindrical external gears for mining & industrial electric locomotive. 2 Referenced standards
JB/T8743—1998
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of the standard, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T1357 — 87 | | tt | T 8539--87
GB/T10095—88
JB2782---79
ZB T04 001—88
ZB J36 009--88
3 Definitions
This standard adopts the following definitions:
3.1 Gear geometric element code
According to GB/T2821.
3.2 Basic gear terminology
According to GB/T3374.
3.3 Tooth core hardness
Involute cylindrical gear module (neqISO54:1977) Gear geometric element code (neqISO701:1976) Technical conditions of alloy structural steel (neqrOCT4543:1971) Basic gear terminology (neqIS0/R1122-1:1983) Involute cylindrical gear load capacity calculation method Mechanical drawing gear drawing method (neqISO2 203:1973) Dimensional data to be indicated on the involute cylindrical gear drawing (eqvISO1340:1976) General provisions for gear material and heat treatment quality inspection Involute cylindrical gear accuracy (eqvISO1328:1975) Metallographic inspection of automobile carbonitriding gears
Metallographic inspection of automobile carburized gears
Metallographic inspection of steel induction hardening parts
According to 2.5 of GB/T8539.
3.4 Effective hardened layer depth
3.4.1 The effective hardened layer depth of carburized (carbonitriding) gears shall be in accordance with 2.9.1 of GB/T8539.
3.4.2 Effective hardened layer depth of surface quenching (flame or induction quenching) gears Approved by the Ministry of Machinery Industry on May 28, 1998
Implemented on November 1, 1998
According to 2.9.3 of GB/T8539.
4 Technical requirements
4.1 Basic tooth profile and module
JB/T8743-1998
4.1.1 Basic tooth profile and tooth profile parameters and code specifications are shown in Figure 1 and Table 1.p
Figure 1 Basic tooth profile of involute cylindrical gear
Tooth profile parameter name
Tooth profile angle
Tooth height
Working tooth height
Radial clearance
Tooth root fillet radius
Basic tooth profile refers to the normal tooth of the basic rack. Number
Baseline
Tooth height coefficient h:=1
The tooth shape in the working tooth height part is a straight line
The tooth thickness and tooth width are equal on the baseline
Radial tracking coefficient C=0.25
2In order to improve the strength of the tooth root, it is allowed to increase P under the condition that there is no interference in the transmission, and it is also allowed to make a single arc. 4.1.2 Tooth top chamfering and trimming
a) In order to improve the transmission quality, the tooth top chamfering or trimming is generally performed. After the tooth top chamfering or trimming, the gear should ensure that the overlap in the gear transmission is not less than 1.089;
b) For gears with an accuracy level of less than 7 (including 7), it is recommended to use the tooth top rounding method, and the tooth top rounding radius R=0.1m.
4.1.3 Gear module
Gear module shall comply with the provisions of GB/T1357. The modules adopted in this standard are 3, 4, 5, 6, 7, 8, 9, 10, and 12 mm. 4.2 Selection of modification coefficient and calculation of geometric dimensions 4.2.1 Selection of modification coefficient
a) The modification coefficient shall be correctly selected, including the sum of modification coefficients x and the reasonable allocation of x= to x: and x2tb) This standard recommends the use of angular modification gear transmission, and xs, xi and x are all greater than zero; c) When allocating modification coefficients, under the premise of comprehensively considering the bending strength, contact strength, anti-adhesion ability and wear resistance of the gear, sufficient attention shall be paid to the fact that the large gear with interference fit on the axle is inconvenient to replace. Calculation of geometric dimensions of angular displacement gears
According to the transmission requirements, after determining the parameters Z1, Z, m, α according to strength calculation or structural design, the calculation of the geometric dimensions of the gears is shown in Table 2. Table 2
Center distance without displacement
Center distance variation coefficient
Engagement angle
Variation coefficient and
Variation coefficient distribution
Tooth height variation coefficient
Pitch circle diameter
Tooth top height
Tooth full height
Pitch circle diameter
Tooth top circle diameter
Tooth root circle diameter
X1, X2
Restrictions on gear displacement and meshing quality index formula or description
0.5m(Z+Z)
(a'-a)/m
arccos[(a · cosa)/a']
0.5(Z,+Z,)(inva--inva)
Select according to design requirements
m(h'+x-△y)
m(2 h,'+e'-Ay)
d[1+2y/(z+)]
d,-2 h
(8~13)m
a) Root cutting is not allowed during gear processing. The minimum displacement coefficient xni to avoid root cutting is calculated as follows: Xmin=h,'+c'-r'(1sina)-zsin'a/2 Where: h=1c=0.25r=0.38a=20°
b) Tooth thickness S.≥(0.3~0.4)m
S,=d(s/d+inva-inva.)
Where: S—division arc tooth thickness, mm, see formula (14); a,
top circle pressure angle, see formula (15). S=0.5 yuan m+2xmtana
α, =arc cos(d,/d,)
Where: ds-base circle diameter, mm, formula (16) d,=m·z·cosa
Formula number
c) The overlap of gear transmission ε should not be less than 1.20. For gears with chamfered or trimmed teeth, the overlap shall be in accordance with 4.1.2a. The overlap ε is calculated as follows:
[z,(tana.-tana')+z(tanaz-tana')]d) Gear transmission shall not have transition curve interference. The condition for small gears not to have transition curve interference is: tana
(tanatana')≥tana-
The condition for large gears not to have transition curve interference is: tana.
2(tana,-tana')≥tana-
4(h, -x,)
Z,·sin2a
Z,·sin2a
JB/T8743--1998
e) When using standard hobs for processing, incomplete cutting of gear teeth shall not occur. The condition to avoid incomplete cutting of gear teeth is: d,sin(α, -α)?～12
>12~18
Quenched and tempered gear
8—7-7
7—6—6
Note: The circumferential speed of the gear indexing circle refers to the circumferential speed of the gear indexing circle of industrial and mining electric locomotives under long-term operation conditions. Hardened gear
8--8-7
7-6--6
4.3.2 This standard stipulates that the accuracy level of the two gears in the gear pair is the same. Different accuracy levels can be selected for the three tolerance groups, but within the same tolerance group, the tolerances and limit deviations should maintain the same accuracy level. 4.3.3 The gear pair has the same accuracy level as the gear. 4.3.4 Surface roughness
a) The roughness of the gear tooth surface, when the accuracy level of the first tolerance group is level 6, R, the value should not be less than 0.8μm; when the first! When the accuracy level of the tolerance group is level 7, the R value should not be less than 1.6μm; when the accuracy level of the second tolerance group is level 8, the R value should not be less than 3.2μm; b) The surface roughness R value of the gear hole should not be less than 1.6umc) The surface roughness R value of the gear journal should not be less than 0.8μm; d) The surface roughness R value of the reference surface should not be less than 1.6μm. 4.4 Gear pair backlash
4.4.1 Tooth thickness measurement
The tooth thickness is measured by the average length of the common normal line and its deviation. The number of teeth k spanned when measuring the common normal line length is calculated as follows: zr1
/(1+)-cos*α-
Rcosav
The calculation result is rounded to an integer according to the digital rounding rule. 2X
anα-invaj-0. 5
The normal length W measured across the k-tooth is calculated as follows: W,=m·cosa[x(k-0.5)+z·inva+2xtana)The result is rounded to 0.01mm.
4.4.2 Limit backlash
The minimum normal limit backlash jamin of the gear pair is calculated as follows: jami=|Eu+E1·cosα—2f, sina-(23)
Where: E——the upper deviation of the tooth thickness of the small gear, μm; E2 the upper deviation of the tooth thickness of the large gear, μm;
JB/T8743-1998
f. f. value of the limit deviation of the center distance of the gear pair, μm; j.—-the reduction of backlash caused by processing and installation errors, μm. j.=b+b+(1.25Xcosa+1)+F
This standard does not assess the maximum normal limit backlash jm of the gear pair. 4.4.3 Gear limit deviation code
This standard recommends: When the accuracy level of the first and first tolerance groups of the gear are both level 8, the upper and lower deviation codes of the tooth thickness of the pinion are F and J respectively, and the upper and lower deviation codes of the tooth thickness of the gear are G and K respectively. When the accuracy level of the first and first tolerance groups of the gear are both level 9, the upper and lower deviation codes of the tooth thickness of the dog and pinion are F and H respectively. The deviation Ews and tolerance T on the average length of the common normal are calculated according to formula (27) and (28) respectively: E., = E.·cosα-0.72F,sina
T, = T, cosα-1. 44 F, · sina4.5 Gear materials and heat treatment
4.5.1. Gear materials
a) Quenched and tempered gears use 40Cr, 42CrMo, 40CrNiMoA; carburized gears use 20CrMnTi, 20CrMnMo. Other alloy structural steels with performance not lower than the above materials are allowed. The material of non-integral gears refers to the gear ring material of the processing gear tooth part; b) The chemical composition and mechanical properties of the material shall comply with the provisions of GB/T3077. 4.5.2 Surface hardness
a) The tooth surface hardness of the gears subjected to induction hardening shall not be less than 48HRC; b) The tooth surface hardness of the gears subjected to overall hardening, carburizing or carbonitriding, shall not be less than 56HRC, and the difference between the hardness of the tooth root transition surface and the tooth groove bottom surface and the tooth surface hardness shall not be greater than 3HRC. 4.5.3 Core hardness
a) The core hardness of the quenched and tempered gears shall not be less than 215HBS, and the quenched and tempered hardness before tooth cutting may be used instead of the core hardness inspection; b) The core hardness of the carburized (carbonitriding) gears shall not be less than 28HRC and shall not be higher than 45HRC. 4.5.4 Effective hardened layer depth
The effective hardened layer depth shall not be less than 0.15 times the modulus, and the difference between the maximum and minimum values shall not be greater than 0.5mm; the hardened layer depth of the tooth groove bottom surface and the tooth root transition surface shall not be less than 75% of the specified minimum value. 4.6 Calculation of bearing capacitywww.bzxz.net
4.6.1 Calculation rules
a) The calculation content is the contact strength of the tooth surface and the bending fatigue strength of the tooth root; b) The calculation method shall be in accordance with the general method in GB/T3480 and the relevant provisions of this standard; c) The calculation conditions shall be in accordance with the hourly or long-term operating conditions of industrial and mining electric locomotives. 4.6.2 Calculation of tooth surface contact strength
a) Strength conditions
The calculated contact stress 6 of the small gear at the lower boundary point of the meshing area of a single pair of teeth shall not be greater than its allowable contact stress oMP, or the calculated safety factor Su of the contact strength shall not be less than the minimum safety factor SHmie of the contact strength. That is: DHOHP
Sk≥SHm
Where the contact stress, N/mm, see 4.6.2b. b) Calculated contact stress H
The calculated contact stress at the lower boundary point of the meshing area of a single pair of teeth is determined by the following formula. 74
In the formula: Ka-
JB/T8743—1998
VK.. K,. Khe. Khe
Service coefficient, this standard stipulates that K=1.25; K,—dynamic load coefficient;
Kn8tooth load distribution coefficient for contact strength calculation; KHa—-tooth load distribution coefficient for contact strength calculation; K, K, KH are calculated according to GB/T3480 respectively; OHO
—basic value for calculating contact stress, N/mm. Ho = -Zh · Ze - Z. - Ze -
Nb·d,
Wherein: F.——nominal tangential force on the pitch circle, N, see formula (33) b-.working tooth width, mm, refers to the smaller width of a pair of gears; d,—pitch circle diameter of the pinion, mm;
u—tooth ratio, =zz/z
Zn—node area coefficient, see formula (34); Z~—elastic coefficient, N/mm2, taken as 189.8 in this standard; Z.-contact coefficient, see formula (35);
Z—conversion coefficient, see 4.6.2.f.
F.=19.098X10°X
Wherein: P—traction motor power under the calculated working conditions of industrial and mining electric locomotives, kW; n,
—gear speed under the calculated working conditions of industrial and mining electric locomotives, r/min. 2
Zh=Ncos'a. tana
Z.= V(4-e)/3
c) Allowable contact stress oHP
The allowable contact stress oHp for large and small gears shall be calculated according to the following formula: Smia·Z·ZL·Zv·Zx·Zw·Zx
Wherein: SHmin
Minimum safety factor for contact strength, see 4.6.2e; Contact fatigue limit of test gear, N/mm; see 4.6.2g; Z Life coefficient for contact strength calculation;
ZL——lubricant coefficient;
Zv——speed coefficient;
Zr——roughness coefficient
Zw—working hardening coefficient
Zx——size coefficient for contact strength calculation; Zs, ZL, Zv, Zx, Zw, Zx shall be calculated according to GB/T 3480 respectively. (31)
（36）
Note: *When calculated as a permanent life, Z=1; when calculated as a finite life, the working life of the gear should be no less than 20,000h, and partial pitting is allowed on the tooth surface.
d) Safety factor S for contact strength calculation
The safety factor Sn for contact strength calculation of large and small gears is calculated as follows: 75
JB/T8743—1998
Sh-SHin ·Zw, ZZv·Z ·Zw · ZxCHO
K..Ky· KH· KH
e) Minimum safety factor SHmin for contact strength (37)
This standard stipulates: The contact strength calculation is carried out under the long-hour operation condition of industrial and mining electric locomotives. The minimum safety factor SHmia for contact strength is 1. 0.
f）Conversion coefficient ZB
Conversion coefficient B is used to convert the calculated contact stress at the pitch circle of the gear into the calculated contact stress at the lower boundary point of the meshing area of a single pair of teeth. For gears with Z≥20, take Zs=1; for gears with Z,<20, Zg is calculated as follows: ZB
Vtanagai · tanap
-The pressure angle of the small gear at the lower boundary point B of the meshing area of a single pair of teeth is calculated as follows: Where:
tanag=tanαa—2n/z,
The pressure angle of the large gear at the lower boundary point B of the meshing area of a single pair of teeth is calculated as follows: tanag
g) Contact fatigue limit of the test gear Him[(u+1)· tana'-tanαn}
1) For gears that are induction hardened and tempered by each tooth and whose materials and heat treatment meet the requirements of this standard, omim=1200N/mm is taken; for carburized (carbonitriding) gears that are hardened as a whole, oHlim=1500N/mm is taken. 2) If there is a lack of material testing and strict heat treatment process and inspection, oHlim=1050N/mm is taken for gears that are induction hardened and tempered by each tooth. For carburized (carbonitrided) gears that have been fully ignited, oHlim = 1350 N/mm2 is taken. 3) In general, the average values of the two are taken. 4.6.3 Calculation of gear tooth bending fatigue strength
a) Strength conditions
The calculated tooth root stress r should not be greater than the allowable tooth root stress oFP, or the calculated safety factor Sr of the bending fatigue strength should not be less than the minimum safety factor SFmin of the bending fatigue strength. That is: CFOt
SF≥SF
b) Calculate the tooth root stress F
Calculate the tooth root stress F by the following formula:
CF=OFO·K·Kv·KF·K
Where: KA, K see 4.6.2b
KFa——tooth load distribution coefficient for bending strength calculation; KF. Inter-tooth load distribution coefficient for bending strength calculation, OFo
Basic value of tooth root stress, N/mm, should be determined separately for large and small gears. F
.Ye· Ys
Where: Ft, b see 4.6.2b;
YF—Tooth shape coefficient when load acts on the upper boundary point of the meshing area of a single pair of teeth: Ys—Stress correction coefficient when load acts on the upper boundary point of the meshing area of a single pair of teeth; K, Kp, Yr, Ys are calculated according to GB/T3480. c) Allowable tooth root stress p
The allowable tooth root stress of large and small gears shall be calculated according to the following formula: 76
（41）
Wherein: oFim
YRrelT
JB/T8743-1998
Sete-Yst. Yur . Ynt . Yrut - Y.SFmin
tooth root bending fatigue limit of the test gear, N/mm, see 4.6.3.f; - stress correction factor of the test gear, when calculated according to the oFlim value given in this standard, Yst=2.0; life factor for bending strength calculation, this standard stipulates that Ynr=1.0; - relative tooth root fillet sensitivity coefficient;
- relative tooth root surface condition coefficient;
size coefficient for bending strength calculation;
minimum safety factor for bending strength.
YelT, YRrelT, Y, are calculated according to GB/T3480. d) Calculation safety factor Sp for bending strength
The calculation safety factor S for bending strength of large and small gears is calculated as follows: Fline·Yst. YnT.
Yret . Yrelt . Y,
K·Ky·Kp·KF.
e) Minimum safety factor Semia..-....
8++eeee
This standard stipulates that the bending strength calculation is carried out under the hourly operating condition of industrial and mining electric locomotives. The minimum safety factor of bending strength Semin = 1.5
f) The bending fatigue limit Flim of the tooth root of the test gear 1) For the heat treatment of the material in accordance with the provisions of this standard, if the hardness of the bottom surface of the tooth groove is the same as the hardness of the tooth surface, flim = 240N/mm;
If the hardness of the bottom surface of the tooth groove is significantly lower than the hardness of the tooth surface, then oFlim = 220N/mm; for the overall quenched carburized (or carbonitrided) gear, oplim = 330N/mm. 2) If there is a lack of material testing and strict heat treatment process and inspection, then oFim 200N/mm is taken for the tooth-by-tooth induction quenched and tempered gear; oFlm = 300N/mm is taken for the overall quenched carburized (or carbonitrided) gear. 3) In general, the average value of the two can be taken. If the tooth surface is strengthened, the value of lim can be appropriately increased. 4.7 Drawing and marking
4.7.1 Drawing
The drawings of gears and gear meshing shall be drawn in accordance with GB/T4459.2. 4.7.2 Gear parts drawings and markings
Gear parts drawings and markings shall be in accordance with GB/T6443. The contents and styles of the parameter table are shown in Table 4. Table 4
Tooth profile angle
Tooth top height coefficient
Modification coefficient
Average length of common normal and its deviation
Number of span teeth
Accuracy grade
Center distance of gear pair and its limit deviation
(GB/T10095)
Matching gear
Tolerance group
JB/T8743—1998
Table 4 (end)
Inspection item code
Note: The inspection items listed in the table are applicable to gears of level 8 and above, and the specific inspection items can be increased or decreased according to actual needs. 4.7.3 Gear assembly drawing annotation
Tolerance (or limit deviation) value
The accuracy grade, backlash requirements, inspection items and tolerance of the gear pair should be marked in the appropriate part of the assembly drawing. Marking example 1
The part number of the pinion in the gear pair in the assembly drawing is 7, and the part number of the gear is 12. The tangential comprehensive tolerance Fc, the tangential comprehensive tolerance of one tooth fic and the contact spot of the gear pair are all level 8; the minimum normal limit backlash jami=223μm, Fz=308μm, fic=73μm. Its marking content and style are shown in Table 5.
(Part number 7/12)Gear pair accuracy grade: pair 8(223)nMinimum normal limit backlash
Inspection items
Marking example 2:
Tangential comprehensive tolerance
Tangential comprehensive tolerance of one tooth
Contact spot
Not less than 40% in height and not less than 50% in lengthit
The part number of the pinion in the gear pair in the assembly drawing is 13, and the part number of the gear is 5. The tangential comprehensive tolerance Fs of the gear pair and the tangential comprehensive tolerance fic of one tooth are both level 8, the contact spot is level 7, the minimum circumferential limit backlash jemin=237μm, Fic=308μm, fic=73μm, and the marking content and style are shown in Table 6.
(Part No. 13/5) Gear pair accuracy grade: pair 887(237)t minimum circumferential limit side exposure
Inspection items
5 Sampling and inspection
5.1 Sampling
Tangential comprehensive tolerance
Tangential comprehensive tolerance of one tooth
Contact spot
Not less than 45% in height and not less than 60% in length. According to this standard, industrial and mining electric locomotive gears shall be sampled by piece inspection. 5.2 Inspection
5.2.1 Tooth damage inspection
Tooth damage shall be inspected according to the relevant items in the following items according to actual needs and in accordance with the provisions of Appendix B Table B1 in GB/T10095. 78
a) Dimensional deviation and shape error of gear hole; b) Dimensional deviation and shape error of gear journal; c) Dimensional deviation of gear circle diameter;
d) Radial runout of reference surface;
e) End face runout of reference surface:
f) Surface roughness.
5.2.2 Gear inspection
JB/T8743—1998
Error inspection items for gears of different accuracy grades are shown in Table 7. Table 7
Accuracy grade
First tolerance group
First tolerance group
First tolerance group
Normal line average length deviation
6, 7, 8
Af and △fg
Note: If the contact spots in the tooth height and tooth length direction can meet the requirements of Table 8, the tooth shape and tooth direction can be exempted from inspection. Table 8
Contact spots of gear pair
Tooth height direction (%)
Tooth length direction (%)
5.2.3 Gear heat treatment inspection
a) Metallographic inspection
1) Induction hardening gears shall be carried out according to ZBJ36009; 2) Carburizing gears shall be carried out according to ZBT04001;
3) Carbonitriding gears shall be carried out according to JB2782. b) Inspection of specimens
Hard tooth surface
AF. and AF.
△f and △fpb
Medium-hard tooth surface
This standard stipulates that the determination of the surface hardness and the depth of the hardened layer of the gear teeth and the metallographic inspection shall be replaced by inspection specimens. The cross section of the inspection specimen should be as similar as possible to the cross section of the gear teeth, and should be the same as the material and heat treatment process of the gear. The number of inspection specimens with the furnace shall not be less than two, and they shall be placed on the top and bottom of the furnace respectively near the gear teeth. In case of dispute, the inspection result of the gear teeth shall prevail. 5.2.4 Gear pair inspection
The inspection items of gear pairs of various accuracy grades are listed in Table 9. Table 9
Tangential comprehensive error of gear pair
Tangential comprehensive error of one tooth of gear pair
Contact spot of gear pair
Minimum normal backlash of gear pair
Note: The tangential comprehensive error △Fi of gear pair and the tangential comprehensive error △fi of one tooth are allowed to be assessed according to the sum of the tangential comprehensive errors △F\ of a single gear and the sum of the tangential comprehensive errors △f of one tooth.
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