JB/T 9127-2000 JB/T 9127-2000 Shot peening technical specification for cylindrical helical springs JB/T9127-2000 Standard download decompression password: www.bzxz.net

JB/T9127--2000
This standard is a revision of the original JB/Z25585 "Technical Specification for Shot Peening of Cylindrical Helical Compression Springs". During the revision, editorial changes were made to the original standard, and the main technical content remained unchanged. Both Appendix A and Appendix B of this standard are appendices to the standard. This standard was proposed and managed by the National Technical Committee for Spring Standardization. Drafting units of this standard: Mechanical Science Research Institute, Wuhan Spring Factory, Wuhan Spring Research Institute, Luoyang No. 1 Tractor Manufacturing Plant, Second Automobile Manufacturing Plant, Nanjing 511 Factory, Guangzhou Spring Factory, Wuxi Spring Factory 626
Standard of the Machinery Industry of the People's Republic of China
Technical Specification
Coiled Helical Spring Shot Peening
Coiled Helical Compression Springs Shot-hlasting Technical Specification1 Scope
JB/T 9127--2000
This standard applies to the shot peening technical specification of cylindrical helical compression springs with a steel wire diameter of Φ1.0~8.0mm cold rolled. 2 Terms
This standard adopts the following definitions.
2.1 Shot Peening
A process means to spray a high-speed projectile stream onto the spring to produce compressive stress on the surface to improve fatigue strength, extend service life and improve stress corrosion resistance. 2.2 Arc height
The surface of the test piece undergoes plastic deformation under the impact of the projectile, making the shot peening surface of the test piece bend in a spherical shape. The distance between the specific reference plane that cuts into the spherical surface and the highest point of the spherical surface is defined as the arc height. 2.3 Shot peening intensity Q
The arc height at the saturation point on the arc height curve is defined as the shot peening intensity. 2.4 Surface coverage
The ratio of the area occupied by the surface craters to the total area after shot peening is the surface coverage. 3 Shot peening method
3.1 Shot peening equipment
There are three main types of shot peening machines: pneumatic, mechanical centrifugal and wet. The main function of the shot peening machine is to make the projectile gain kinetic energy and make the spring move to ensure that the spring obtains the specified shot peening intensity during shot peening. 3.2 Projectiles
The projectiles used for shot peening include wire cut shot, cast steel shot, stainless steel shot, glass shot, etc. The shape of the projectile must be spherical. The broken projectiles should be screened and separated regularly and timely. The sharp edges of the steel wire cut projectiles should be removed before use. The projectiles are selected according to the material, specifications and technical requirements of the springs to be sprayed.
3.3 Test piece
3.3.1 Material
The test piece is made of 70 steel or 65Mn cold-rolled spring steel strip. 3.3.2 Hardness
The test piece should be heat treated and the hardness should be 44~50HRC. 3.3.3 The dimensional accuracy shall be in accordance with the provisions of Table 1 and Figure 1. Table 1
Approved by the National Machinery Industry Bureau on April 24, 2000 Thickness
0.787±0.025
1.295±0.025
2000-10-01 Implementation
3.4 ​​Support fixture
JB/T9127
Return 0. 025
0. 025
3.4.1 The specimen support fixture can be made of carbon structural steel. The dimensional accuracy shall be in accordance with the provisions of Figure 2 or Figure 3. 40±0.4
3.4.2 The specimen support fixture shall be inspected regularly and replaced in time if damaged. 3.5 The structure and dimensional accuracy of the arc height gauge shall be in accordance with the provisions of Figure 4. 628
JB/T 9127--2000
[6.8 (maximum)
[4x ball
The four contact ball heads must be kept in the same plane, with a tolerance of ±0.05mm Figure 4
3.6 Preparation before shot peening
3.6.1 The spring must reach the specified process dimensions before shot peening. 3.6.2 The spring must undergo the specified heat treatment before shot peening. 3.6.3 The test piece and the support fixture shot peened together with the spring shall meet the requirements of 3.3 and 3.4. The test piece must be fastened at four points when installed on the support fixture.
3.6.4 The surface of the spring should be dry, clean, and free of oil and other corrosive substances. 3.7 Quality control of shot peening
3.7.1 The surface coverage of the spring after shot peening should be above 90%. 3.7.2 When using A-type test piece to check the shot peening strength, the shot peening strength is selected in the range of 0.15A to 0.16A; when using N-type test piece to check the shot peening strength, it is selected in the range of 0.15N to 0.46N. 3.8 Treatment after shot peening
3.8.1 After shot peening, springs are allowed to be tempered, but the maximum tempering temperature shall not exceed 250℃. 3.8.2 If the springs after shot peening need to be surface treated, the heating temperature in each process should be controlled below 250C. 3.8.3 After shot peening, springs are allowed to be repaired by mechanical methods. Usually, repair is only allowed in the direction where the spring bears the load. 3.8.4 The surface of the spring after shot peening is prone to rust and must be immediately treated with anti-rust. 4 Inspection method
4.1 Before shot peening, the batch springs should be subjected to the first shot peening strength inspection test. Shot peening can only be carried out after the test results meet the technical requirements of the batch springs. And regular sampling inspections should be carried out during the shot peening process. 4.2 The measurement method of arc height value is shown in Figure 5. 629
JB/T9127--2000
4.3 The surface coverage is measured with a 5-10 times magnifying glass. When checking with a 10 times magnifying glass, make a judgment by referring to Figures 6 to 9. 4.4 The measurement method of shot peening intensity and the measurement method of surface coverage are shown in Appendix A (Standard Appendix) Appendix B (Standard Appendix) Figure 6 95%
Figure 8 80%
Figure 7 90%
Figure 9 50%
JB/T 9127--2000
Appendix AbZxz.net
(Appendix of the standard)
Measurement method and selection of shot peening intensity
Arc height is a function of shot peening process parameters (shot diameter, shot velocity, charge, spring loading, spray time, spray angle, etc.). When other conditions are fixed, it increases with the increase of shot peening time (or shot peening times), then gradually changes slowly and finally reaches "saturation". Although arc height is a variable. Relatively speaking, shot peening intensity is a constant, corresponding to the arc height curve, there is only one "saturation" point (when the time increases by - times, the arc height increase is less than 10%, which is the "saturation point"). That is, there is only one shot peening degree. A1 Method for determining shot peening intensity
A1.1 Fasten the test piece to the supporting fixture with four screws. A1.2 Start shot peening with the supporting fixture and spring on which the test piece is mounted. A1.3 Stop the machine after shot peening for a certain period of time. Remove the test piece from the fixture and measure the arc height of the test piece on the arc height gauge. A1.4 Take another test piece and repeat the operations specified in A1.1, A1.2 and A1.3. Several test points can be obtained (at least six test points should be obtained). Plot these data on the arc height shot peening time coordinate diagram to obtain: a line as shown in Figure 8.1 (i.e., arc height curve).
The increase in height is less than 1!
A2 Selection of shot peening intensity
A2.1 If the spring drawing has clear requirements for shot peening intensity, it shall be carried out according to the requirements of the drawing. A2.2 If the spring drawing has clear provisions for fatigue, the shot peening intensity shall be selected to ensure that the spring fatigue meets the requirements of the drawing. A3 Shot peening strengthening example
A3.1 Determination of shot peening intensity
Material of the test spring: 65Mn
Spring specification: steel wire straight Diameter d=4.5mm
Convolution ratio C=6.5
Total number of turns ni=8.25
Shot peening equipment: Q3110 shot peening machine
JB/T9127—2000
Shot type and size: cut wire shot d=0.6～~1.0mmCoverage rate:>90%
Use type A test piece to test the arc height value
Change the shot diameter, part loading and shot loading to obtain different shot peening intensities. As shown in Figure A2, Figure A3 and Figure A4. 9.
Shot peening intensity Q-0.34
Time min
A3.2 Shot peening of high-strength stainless steel spring
Wire diameter 3mm
Maximum working stress 882N
Cyclic stress ratio r=0.3
Unshot peened spring 7.2×104 fractured
After shot peening:
Glass shot d=0.35~0.45mm
Coverage 200%
Shot peening intensity 0.44A
Time min
Shot peening intensity Q=0.47
Time min
Shot peening intensity Q=0.44
Fatigue test after shot peening was continuously tested by 1×107
Conclusion: Increase the service life by 138 times
A3.3 Determination of surface coverage
Shot peening equipment: Q3110 shot peening machine
Test piece material: 65Mn44~~49 HRC
Projectile: 0.6~0.8mm steel wire cut shot
Shot quantity: 45~50kg
Loading quantity: 40kg spring
JB/T9127—2000
44-47 HRC
The test piece was installed on the supporting fixture and then shot peened together with the spring. The shot peening time was 2.5, 3.5, 5.7.9, 10, 20 and 25min respectively, and different coverage rates were obtained (see Figure A5). 10
B1 Inspection method of surface coverage
Appendix B
(Standard Appendix)
Inspection method of surface coverage
Time min
B1.1 Use a 5x or 10x magnifying glass to inspect the shot peened surface. The area occupied by the craters per unit area should be at least 90%. B1.2 The coverage exceeding 100% is determined by the shot peening time. For example: the shot peening time for 200% coverage is twice the time required to obtain 100% coverage.
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