Constant elastic alloy 3J21 torsion spring vacuum aging treatment process

(Co40CiNiMo) has a high elastic modulus and elastic limit, while having high thermal stability and fatigue strength, non-magnetic, corrosion resistance, is widely used in aviation, electronics, machinery, electric vacuum, instrumentation, etc. Used to make key elastic components. The torsion spring () produced by our company uses this material. The shape of the part is relatively complex and requires high precision. The processed part requires the length of the long arm to be within (10±0.05) mm, the size of the short arm within (6.5±0.05) mm, and the working angle at 49. 8*~50.5°. The diameter of the inner hole of the spring is guaranteed to be 2.2mm, and the spring rigidity is between 0.132 and 0.140. When the spring is used, it is required to be used in pairs. The paired two pieces of spring must have the same rigidity and no scratch on the surface. Its main processing process is: cutting-test wire diameter uniformity NC coil spring machine winding-- vacuum elasticity aging test stiffness and dimensional tolerance. Because the part is processed by 0.4 wire of rice, the supply state of raw materials is drawn hard state, after the parts are coiled, vacuum elastic aging is required, aging treatment is to ensure that the parts have good mechanical properties and elastic properties, but also To ensure the final size requirements, therefore, heat treatment is the key to the processing of the part.

The test pieces were vacuum heat treated with ZG464 high-vacuum furnace. The furnace temperature uniformity was within 2*C and the vacuum was 6X10-5Pa. The spring was tested using a TN-5 spring torsion tester manufactured by Guilin Reiter.

1 Test materials and equipment Test 0.4 for 3J21 alloy, the chemical composition in Table 1: Table 1 3J21 alloy chemical composition (0 balance 2 heat treatment before the treatment process First put the test pieces into aviation gasoline for degreasing cleaning, and then put Into the oven, at 70 * C bake 10min and then into the anhydrous alcohol in dehydration cleaning, cleaning into the oven, and then in the 70 and then into the fixture (see) aging time after clamping (Figure left two parts not added Pressure plate and screw.) 3 Test methods 3. Test results at different aging temperatures without using a jig.) The recommended heat treatment aging temperature is 450 to 550. According to [3], 3J21 is used as an elastic member. When the aging temperature should not be used for each furnace, 10 parts that have passed the inspection should be selected. Parts before and after the aging treatment are tested and the dimensions are recorded. The results are shown in Table 2. Table 2 Different Fixtures and Different Aging Temperatures Effect on Part Size Aging Temperature Long Arm Aging Pre-Long Arm Aging Post Size Short Arm Aging Front Arm Post Aging Post Aging Work Aging Post Work Aging Front Inner Hole Aging Post Boring Diameter Stiffness Size/mm Average/mm Size/mm Average/mm Angle 8°) Diameter/mm Average/mm 21 Feng 21 Table 3 Test Results at Same Fixture and Same Aging Temperature Aging Temperature Long Arm Aging Size /mm Long arm after ageing Size/mm Short arm Aging size/mm End arm ageing size/mm Aging front working angle 八°) Aging after working angle 八°) Aging 内孔孔/mm Aging 内孔孔/ Mm Stiffness 3. Test results when using the same fixture and the same ageing temperature According to the data in Table 2, 470*C is used for aging during the formal production, the holding time is 4 hours, and 10 pieces of the qualified parts are selected for each furnace before and after the aging treatment. All have been tested and dimensions have been tested and recorded. The results are shown in Table 3. 4 Analysis of test results 4.1 Through the analysis of the test data in Table 2, it can be seen that the mean value of the torsion spring long arm length after the 450C aging is 9.97mm within the design requirement (10±0.05); the average size of the short arm 6.47 within the design requirements (6.5*0.05); work angle 49*~51* within 48~55° of design requirement; spring inner hole diameter size 2.05mm, smaller than design requirement by 2.2mm by 0.05mm. In the process of the reason, the spring stiffness was tested and the stiffness was between 0.117 and 0.122, which did not meet the design requirements of the spring stiffness between 0.132 and 0.140. The 10 specimens treated with the 470C process in Table 2 are effective, and the mean length size of the long spring of the torsion spring is 9.90, which is not within the design requirement (10±0.05); the average size of the short arm is 6.42mm, which is not the design requirement (6.5*0.05). ) Within mm; working angle 49*~51°, within the design requirements 48*~55*; spring inner hole diameter to 2. 1mm, than the design requirements 2. Small 0.1mm In the process of analysis of the reasons, The stiffness of the spring was measured and the stiffness was between 0.132 and 0.138, which was in accordance with the design requirements for the spring stiffness between 0.132 and 0.140. At the same time, it can be seen that the stiffness dispersion is large and the pairing use rate is low during assembly. Ten specimens treated with the 480C process shown in Table 2 were used. The average length of the long arm of the torsion spring after aging was 9.90 mm, which was not within the design requirement (10*0.05) mm; the average length of the short arm was 6.42 mm, which was not a design requirement (6.5). * 0.05) mm or less; working angle 48* ~ 50 ° in the design requirements 48 * ~ 55 * less than the diameter of the spring inner hole 2.1mm than the design requirements of the size of 2. 2mm small 0.1mm. In the analysis of the causes of the process, The stiffness of the spring was measured. The stiffness was between 0.138 and 0.142. Some of the stiffness values ​​did not meet the design requirements of the spring stiffness of 0.132 to 0.140. At the same time, it can be seen that the stiffness dispersion is large and the pairing use rate is low during assembly.

4.2 Ten specimens treated with the 470C process in Table 3 were clamped using the fixture shown in the aging treatment, and the mean length of the torsion spring after the aging was within 9.97 05); the working angle was within 48* to 50*, The inner diameter of the spring hole 2. 2. In the process of analysis of the reasons, the spring stiffness was tested, the stiffness was 0. 137, the stiffness value meets the design requirements of the spring between 0.132 ~ 0.140. At the same time, it can be seen that the rigidity dispersion is small and the pairing use rate is high when assembling.

From the above, it can be seen that after the heat treatment, the test piece without the clamp is greatly changed in size and rigidity, which exceeds the design requirements. This shows that the clamping treatment with the clamp is necessary and the effect is very obvious.

5 Conclusions The test results show that the best aging process of the torsion spring is 470C insulation, 3.5h. After the aging under the fixture, the length of the torsion spring long arm is within (10*0.05) mm, and the short arm length is (6.5*). Within 0.05mm, the working angle is within 49.8 to 50.5, and the inner diameter of the spring ensures that the spring stiffness of 2.2 is between 0.132 and 0.140. By adopting the above process, the qualification rate of the part size and the rigidity can reach 98% and the matching success rate when using the spring is improved.

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