JB/T 7909-1999 This standard is a revision of JB/T 7909-95 "Wet Sintered Metal Friction Material Friction Performance Test Bench Test Method", and the technical content was modified during the revision. This standard specifies the test method for determining the friction performance of friction materials. This standard is applicable to the determination of the friction coefficient, wear rate and energy load allowable value of sintered test pieces under lubricated conditions. This standard was first issued on February 11, 1989 as GB 10428-89 and was adjusted to JB/T 7909-95 on April 14, 1996. JB/T 7909-1999 Wet Sintered Metal Friction Material Friction Performance Test Bench Test Method JB/T7909-1999 Standard Download Decompression Password: www.bzxz.net

1CS77.160
Machinery Industry Standard of the People's Republic of China
JB/T7909-1999Www.bzxZ.net
Wet Sintered Metal Friction Materials
Friction Performance Test Bench Test Method
Bench test method for frictional characteristics of sintered metal friction materials run in lubricants1999-08-06Published
National Bureau of Machinery Industry
2000-01-01Implementation
JB/T7909-1999
This standard is a revision of JB/T7909-95 "Wet Sintered Metal Friction Materials Friction Performance Test Bench Test Method". Compared with JB/T7909--95, this standard adds the calculation formula for the average dynamic friction coefficient and uses the integral formula instead of the summation formula to calculate the energy density.
This standard replaces JB/T7909-95 from the date of implementation. Appendix A of this standard is the appendix of the standard.
This standard is proposed and managed by the Technical Committee for Standardization of Powder Metallurgy Products. The drafting units of this standard are: Hangzhou Powder Metallurgy Research Institute: Huangshi Friction Material Industry Company. The main drafters of this standard are: Chen Jinxin, Xie Fanghai, Lu Naiguang, Shen Junchu, Liang Zifang. This standard was first issued as GB10428-89 on February 11, 1989, and the standard number was adjusted to JB/T790995 in April 1996.
1 Scope
Mechanical Industry Standard of the People's Republic of China
Wet Sintered Metal Friction Materials
Friction Performance Test Bench Test Method
Bench test method for frictional characteristics of sintered metal friction materials run in lubricants This standard specifies the test method for determining the friction performance of friction materials. JB/T7909-1999
Replaces JB/T790995
This standard is applicable to the determination of the friction coefficient, wear rate and energy load allowable value of sintered test pieces under lubricated conditions. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T3141-1994 ISO viscosity classification of industrial liquid lubricants 3 Terms and symbols
This standard adopts the following definitions.
3.1 Gross area
The single-surface area calculated based on the actual inner and outer circle dimensions of the friction lining surface, cm. 3.2 Net area A
The single-surface area after deducting the oil groove area from the gross area, cm. 3.3 Friction pair failure
Under the specified test conditions, the friction pair transitions from the normal state to a state that cannot work normally. 3.4 Energy density W,
Friction work per unit net area borne by the friction pair during one engagement process, J/cm. 3.5 Maximum power density N,
The maximum power per unit net area borne by the friction pair during the engagement process, W/cm. 3.6 Allowable value of energy load C,
The product of the energy density W of the friction pair before failure under the specified test conditions and the maximum power density N. 3.7 Average power density N,
Energy density per unit time, W/cm. 4 Test device
4.1 The inertia braking test device consists of a drive mechanism, an inertia wheel, an engagement frequency control system, a measurement system, a clutch, a brake and an oil supply system.
JB/T7909-1999
4,2 The measurement system should be able to measure relative speed, pressure, torque, engagement time and lubricating oil temperature. 4.3 The oil supply system should be able to provide sufficient heat exchange capacity. 5 Test pieces
Test pieces include sintered pieces and dual pieces. Three types of test pieces are recommended. Their geometric dimensions and technical requirements are shown in Figures A1 to A3 in Appendix A (Standard Appendix).
5.1 Running-in
Select appropriate running-in conditions. Run-in until the contact area of ​​the sintered piece accounts for more than 80% of the net area. The running-in is considered complete. 5.2 Arrange points according to Figure 1, use a micrometer to measure the thickness at 8 points, and calculate the arithmetic mean h. (cm). Figure 1
Determination and calculation of friction coefficient
6.1 Test conditions
The test conditions are shown in Table 1. Other test parameters can also be selected according to the situation. Table 1
Average power density
Joining frequency
Joining time
Pressure rise time
Type of lubricating oil
Number of joining
Oil supply (gross area)
Oil temperature at entrance
Times/min
cm/(min·cm)
1.0 ±0.1
The viscosity grade of mechanical oil is 32 (GB/T3141) or 200 as needed
60 ± 5
6.2 Test procedure
JB/T7909-1999
Adjust the surface pressure so that the joining time is (1.0±0.1)s, and the pressure rise time should be limited to within 0.10s. 6.2.2
Adjust the speed and inertia so that the average power density N on the net area of ​​the friction plate is 115W/cm. If necessary, adjust the surface pressure to ensure that the engagement time is (1.0±0.1)s. 6.2.3
6.2.4 Determine the dynamic friction coefficient during the 50th, 100th, 150th, and 200th engagements and the static friction coefficient after engagement. Data collection should be completed in one continuous test.
6.3 Calculate the instantaneous dynamic friction coefficient according to formula (1). (t)μ()=M(t)/(pArz)
Where: M(t)-instantaneous torque, N·m;-surface pressure, Pa;
average radius, m;
Z-number of friction surfaces.
6.4 Calculate the average dynamic friction coefficient μ during the engagement process according to formula (2). @
6.5 Determination and calculation of static friction coefficient
（2）
After completing the 50th, 100th, 150th, and 200th engagements, remove the pressure and then re-apply pressure; determine the static torque during slippage and calculate it according to formula (3):
μ,-M/(pArz)
Where: M static torque, N·m.
7 Determination and calculation of test piece wear rate
·（3）
7.1After 2000 engagements according to Table 1, take out the test piece and measure the thickness of each point of the original mark on the test piece with a micrometer. Calculate the arithmetic mean h, (cm).
Calculate the wear rate 8, cm according to formula (4):
h. -h,
Where: number of engagements.
8 Determination and calculation of energy load allowable value
8.1 Principles for determining the test method
This test uses an average power density of 115Wlcm2 as the starting test condition, and determines the energy load allowable value of the friction pair by gradually increasing the average power density. The test starting conditions and super tests can also be determined based on material properties. 8.2 Determination of energy load allowable value
First, fix the speed and inertia, increase the surface pressure to shorten the engagement time, and increase the average power density (see Table 2); if the friction pair does not fail after the test in Table 2, further increase the energy density and average power density, and keep the other parameters unchanged, and conduct the next test until failure. Test parameters
Average power density
Joining rate
Number of joints
Type of lubricating oil
Oil supply
Oil temperature at inlet
Test level
Times/min
cm/（min·cm）
Level 1 test
115~128
JB/T7909 -1999
Level 2 test
128~144
Level 3 test
144~164
Level 4 test
164~192
Level 5 test
192~230
The viscosity grade of the machine oil is 32 (GB/T3141), or 8
60 ± 5
8 as required.3 Determination of friction performance failure of friction pair
Level 6 test
230-288
Determine based on the torque curve. Stop the test when the torque curve changes abnormally. Disassemble and inspect the test piece, observe and record the failure of the friction pair.
8.4 Value and calculation of energy load allowable value The energy load allowable value is the average value of the 100th, 120th, 140th, 160th, 180th, and 200th test data of the round of test before the friction performance failure of the friction pair.
Energy density W is calculated according to formula (5):
Where: (t) angular velocity, rad/s;
t. —Engagement start time, s;
t——Engagement completion time, s.
The maximum power density N is calculated according to formula (6): N
Wherein: (M)
M(t)w-(t)dt
(M@)
The maximum value of the product of the membrane torque and its corresponding angular velocity during the bonding process, W. The energy load allowable value C is calculated according to formula (7): C = W, N,
9 Test report
The test report should include the following contents:
a) State the geometric dimensions, accuracy, material, form, state and other relevant information of the test piece; (5)
(6)
b) Indicate the test conditions for determining the friction coefficient and the energy load allowable value, and indicate the speed, inertia and surface pressure under the test conditions;
c) Draw the relationship curve between the average dynamic friction coefficient, static friction coefficient and the number of engagements; d) Draw the relationship curve between the dynamic friction coefficient and the relative speed: e) Give the wear rate of the friction material and, if necessary, the wear rate of the mating material: f) Give the energy load allowable value C;
g) Record the failure of the friction performance of the friction pair; h) Other relevant information about the test process.
JB/T7909-1999
Appendix A
(Appendix to the standard)
Geometric dimensions and technical requirements of the test piece
The geometric dimensions and technical requirements of the test piece are shown in Figures A1 to A3. (disappearance)
oil horizontal enlargement
144H10 (14)
center 145 (pitch circle)
point 190
a) sintered sheet
3h10 (-go
equal account shortage 0.02
b) dual sheet
pressure angle
rod distance
involute
14.07-1-27
pressure angle
normal length
involute
78.641-333
235.45H11
center 242.25 (pitch member
JB/T7909-1 999
Oil fine magnification
a) Sintered sheet
13.5H12 (@1M
b) Dual sheet
Pressure angle
Rod spacing
3JS12. (±0.05)
Equal thickness difference 0.03
Involute
60 (division
Electricity: 118
JB/T7909-1999
Precision magnification
a) Sintered sheet
b) Dual sheet
Pressure angle
Accuracy level
Pressure angle
Accuracy level
Involute
Involute
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