The 1st step is to coil the spring. Coil the steel wire according to the direction of rotation, prefabricated height, outer diameter and number of turns, and tighten both ends of the spring;

The 2nd step, tempering, put the spring into the tempering furnace for stress relief tempering;

The 3rd step is end grinding, grinding the two ends of the spring flat, and the grinding angle is greater than 300 degrees;

The 4th step, shot blasting, three shot blasting, the diameter of the first shot blasting is larger than the diameter of the second shot blasting, and the diameter of the second shot blasting is larger than the diameter of the third shot blasting;

The 5th step is creep tempering, compress the spring to the positioning length and fix it on the fixture, put the fixture with spring into the tempering furnace to keep warm, and water cool to room temperature immediately after it comes out of the oven;

The 6th step is to clean the spring with an ultrasonic cleaner;

The 7th step, demagnetization;

The 8th step, anti-rust treatment.

In the production process, three shot blasting is used, the compressive stress on the inner surface of the spring reaches -976MPa, the peak stress reaches -1246MPa, and the stress at a depth of 0.04mm from the surface reaches -1163MPa, and the fatigue life of the spring is 1100MPa at the working pressure and the stroke is 30mm The time is increased from 800,000 times to 2 million times, and the diameter of each shot blasting decreases, which increases the residual stress of the shallow surface layer and improves the surface finish. In order to reduce the heat attenuation of the spring, the creep tempering process is adopted. The shot blasted spring is first compressed to the fixed length and then put into the continuous mesh belt tempering furnace together with the compressed and fixed fixture. After heat preservation, it is water-cooled to At room temperature, the thermal attenuation rate of springs treated by creep tempering is reduced from 3.62-4.21% of normal hot-pressing treatment to 1.44-1.64%, which meets the requirement of spring thermal attenuation rate of less than 3% for some equipment using springs. Pollutants after cleaning < 8mg/m2, remanence after demagnetization < 5 gauss. The treated spring is especially suitable for use in automotive hydraulic torque converters, where the fatigue life of the spring under high stress in the thermal environment is required, and a low thermal decay rate is required.

As preferably, the diameter of described shot blasting for the first time is 0.6 ~ 0.8mm, and the shot blasting frequency is 60HZ, and the diameter of shot blasting for the second time is 0.4 ~ 0.6mm, and the shot blasting frequency is 50HZ, and the shot blasting frequency for the third time is 50HZ. The diameter is 0.2~0.3mm, the shot blasting frequency is 50HZ, and the time of each shot blasting is 20~40 minutes. Choose different parameter values for the three shot blasting, set according to the mechanical properties required by the spring, select the appropriate steel shot diameter and shot blasting frequency to achieve the mechanical properties required by the spring, the frequency of the first shot blasting and the next two shot blasting The frequency of the shot is different, and the steel shots with different diameters are carried out at different frequencies during the next two further treatments. The fatigue life of the third shot blasting is 1.5 times higher than that of the second shot blasting.

More preferably, the temperature of the creep tempering is 200° C. to 300° C., and the temperature is kept for 20 to 40 minutes. Tempering and heat preservation are carried out at the temperature and time within the above range to reduce the amount of thermal relaxation deformation and improve the mechanical properties of the spring.

More preferably, the temperature of the creep tempering is 200° C. to 300° C., and the temperature is kept for 20 to 40 minutes. Tempering and heat preservation are carried out at the temperature and time within the above range to reduce the amount of thermal relaxation deformation and improve the mechanical properties of the spring.

Preferably, the prefabricated height=finished product length+creep attenuation length, the positioning length is the minimum working length of the spring, and the creep attenuation is obtained according to the creep tempering experiment of the spring at the positioning length. The creep tempering temperature of the creep attenuation test is 200°C~300°C, and the temperature is kept for 20~40 minutes. The creep attenuation is obtained through the above experiment. According to the different lengths of springs to be processed, the prefabricated lengths of different coil springs and the positioning lengths of creep tempering are determined to improve the qualified rate of products.

As a preference, before coiling the spring, carry out the first sample, complete all production process processing, determine whether the final product meets the requirements of the drawing, and fine-tune the production process parameters. Trial run on the assembly line first, so that the corresponding process parameters can be better adjusted, so that the pass rate is high during mass production, and the operating cost is reduced to increase the yield.

As more preferably, the raw material is inspected before the first sample, and the steel wire diameter, material tensile strength, and surface quality are inspected. Inspection of materials ensures proper functioning of springs in hot oil environments.

Preferably, a size sorting step is inserted between the fifth step of creep tempering and the sixth step of cleaning. After the sorting process, the first production inspection of the spring is realized, and the yield rate is improved.

Preferably, the temperature of the stress relief tempering in the second step is 400°C-420°C, and the holding time is 55-65 minutes.

Therefore, the manufacturing process of the spring of the present invention has the following advantages: the use of three-stage shot blasting improves the fatigue life of the spring under high stress and long test strokes, so that the spring can be used in a relatively high-demand environment; The variable tempering process, compared with the original hot pressing process, can reduce the amount of thermal relaxation and deformation, reduce the amount of heat attenuation, and can meet the requirements of the hydraulic torque converter assembly.

Detailed ways

  Below through embodiment, the technical solution of the invention is described further in detail.

  Example 1:

The manufacturing process of the spring includes the following processes:

The first step is to coil the spring. The steel wire is coiled according to the direction of rotation, prefabricated height, outer diameter and number of turns, and the two ends of the spring are tightened together to complete the preliminary spring shape;

The second step, tempering, put the spring into the tempering furnace for stress relief tempering;

The third step is end grinding, grinding the two ends of the spring flat, and the grinding angle is greater than 300 degrees;

The fourth step, shot blasting, three shot blasting, the diameter of the first shot blasting is larger than the diameter of the second shot blasting, the diameter of the second shot blasting is larger than the diameter of the third shot blasting, the first shot blasting The frequency is higher than the frequency of the second and third shot blasting, the three shot blasting times are the same, and the residual stress and fatigue life are improved after shot blasting;

The fifth step is creep tempering, compress the spring to the fixed length and fix it on the fixture, put the fixture with the spring into the tempering furnace to keep warm, and water cool to room temperature immediately after it comes out of the furnace, so as to reduce thermal relaxation and deformation, and increase the heat decay rate ;

The sixth step, cleaning, cleaning the spring with ultrasonic waves;

The seventh step, demagnetization;

The eighth step, anti-rust treatment, immerse in anti-rust oil.

Among them, the prefabricated height = finished product length + creep attenuation length, the positioning length is the minimum working length of the spring, and the creep attenuation is obtained according to the creep test of the spring at the positioning length. That is, first get the spring that the target requires to be processed, and its positioning length is known. After the spring is compressed to the positioning length, it is kept in a tempering furnace with a tempering temperature of 240°C for 35 minutes. The creep attenuation is obtained through the above experiment. quantity. Carry out tests to calculate the creep attenuation length, so as to obtain the prefabricated height, and process according to the above-mentioned process according to the test data.

Example 2:

If it is necessary to make a spring with a length of 68mm and an outer diameter of 13.5mm, using the manufacturing process of the spring of the present invention, the spring is first rolled, the steel wire is wound and the two ends of the spring are tightened, and the spring parameter after winding is 13.6 ±0.1mm, the prefabricated height is 79±0.5mm, and the total number of turns is 17.8; then, carry out stress-relief tempering on the coiled spring in a tempering furnace with a tempering temperature of 410±10°C, and the tempering holding time is 60 ±3 minutes; After the tempering treatment is completed, the end faces of the springs are ground, and the two ends are ground flat, and the angle of the grinding surface is greater than 300 degrees; after the grinding, the shot blasting treatment is carried out, and the shot blasting treatment includes 3 shots. A steel shot with a diameter of 0.6mm is shot blasted in a shot blasting machine with a frequency of 60HZ for 30 minutes, and then the second shot is shot, and the second shot is shot with a steel shot with a diameter of 0.4mm at a frequency of 50HZ. Shot blasting in the shot blasting machine for 30 minutes, and then the third shot blasting is carried out. The third shot blasting uses steel shots with a diameter of 0.3mm in the shot blasting machine with a frequency of 50HZ for 30 minutes; after The spring after shot blasting is put into the tempering furnace for creep tempering. The creep tempering is to compress the spring after shot blasting to the positioning length of 36.5mm (that is, the minimum working length of the spring) and fix it with the clamp, and then the clamp Bring the spring into the 240-degree continuous mesh belt tempering furnace, keep warm for 35 minutes and then water-cool to room temperature. The length of the cooled spring is 68mm; then clean the spring with an ultrasonic cleaner to make the pollutants <8mg /m2, after cleaning, use a demagnetizer to demagnetize the spring to make the residual magnetism <5 gauss, and finally immerse the spring in anti-rust oil for anti-rust treatment.

Example 3:

The production process of the spring, the first step is to inspect the raw materials, check the diameter of the steel wire, the tensile strength of the material, the surface quality, etc., to ensure the normal work of the spring in the hot oil environment; the second step is to carry out the first sample , according to the online equipment, complete all production process processing, determine whether the final product meets the requirements of the drawing, and fine-tune the production process parameters; the third step is to coil the spring according to the spring parameters such as the outer diameter of the spring, the prefabricated height, and the total number of turns. And tighten the two ends of the spring; the fourth step is to carry out stress relief tempering in the tempering furnace, the tempering temperature is kept at 400 degrees, and the temperature is kept for 60 minutes; the fifth step is to grind the two ends of the spring, and the grinding surface angle Greater than 300 degrees; the sixth step is to carry out three shot blasting, the first shot blasting diameter is 0.7mm, the shot blasting frequency is 60HZ, the second shot blasting diameter is 0.5mm, the third shot blasting diameter is 0.3mm, and the third shot blasting diameter is 0.3mm. The frequency of the second and third shot blasting is 50HZ, and the third shot blasting time is 30 minutes; the seventh step, creep tempering, press the spring to the fixed length with a clamp, put it in the tempering furnace for 30 minutes and then cool it with water to room temperature; step 8, size sorting according to product specifications; step 9, clean the spring with an ultrasonic cleaner; step 10, demagnetize the spring with a demagnetizer; step 11, immerse the spring as a whole The antirust oil is subjected to antirust treatment; the twelfth step is to pack.