Custom Springs and Wire forming

Inspection content and specification for Metal spring

The following are the main inspection of springs

1.Test classification
A) first inspection;
B) quality consistency check.

2. A spring group of groups
Springs shall be checked in batches, each of which shall be made up of the same material specifications, grades, melting furnace number and the same technological conditions.

3. First test
The identification and inspection of the production of 3.1 spring first parts must be carried out according to the test or inspection items stipulated in the drawings, and the judgment of qualified and unqualified must be made.
The first part of the 3.2 spring must be fully checked and recorded, and the inspector will notify the technician of the test results.

4. Quality conformance test
The scope of application of the 4.1 whole test:
4.1.1 small batches of springs, such as less than 50 pieces;
4.1.2 special important spring, after damage will jeopardize personal safety and major economic losses, such as nuclear power stations, aeroengines, seismometers and other springs;
4.1.3 can automatically detect items such as spring load, free height, and so on.
4.2 the scope of application of sampling inspection:
4.2.1 large spring, more than 500 pieces;
4.2.2 inspection items with high cost and long period, such as fatigue test, creep and relaxation test, etc.
4.2.3 has destructive testing items, such as impact test, metallographic organization, decarburization and hardness test, etc.
4.2.4 has a certain degree of disqualification, which will not cause great influence on the inspection items, such as the end ring clearance, verticality and so on.
4.2.5 large quantities, and can not be automatically tested, such as the surface quality of the spring.
There are many kinds of springs. Their inspection items and requirements can be determined by the technical standards and specifications of each spring. This paper mainly introduces the inspection and requirements of cylindrical helical spring products, so as to make reference for other springs.

5. Inspection of the quality of spring appearance
The appearance quality of spring in the oil after blasting by visually or with five times the magnifying glass inspection. When special requirements are required, ultrasonic testing or magnetic powder detection can also be used.
The appearance quality of spring: spring ring no obvious twisting and bending phenomenon, spring should remove surface dirt, mark, mark and lead salt oxide; no spring surface crack, spall, scarring and corrosion, but in the guarantee method allows the material removed by grinding section dimension deviations range is the grinding part should be smooth; the spring surface scratches, abrasions or individual dent depth is less than half of the diameter of the material tolerances allowed.

6. Detection of geometric size of cylindrical helical spring
The measurement of geometric size of cylindrical helical spring is shown in Table 1, and the content detection of the table column is selected according to the type of spring and the requirement of the drawing.
Detection of geometric size of 6.1 compression springs
Measuring the diameter of 6.1.1 spring material:
6.1.2 spring free height or free length detection:
Detection of 6.1.3 spring diameter:
Detection of the number of 6.1.4 spring rings:
Detection of end gap and end thickness of 6.1.5 spring.
The measurement of the pitch uniformity of the 6.1.6 spring:
6.1.7 spring pressure and height detection:
Detection of 6.1.8 spring grinding:
Detection of end surface grinding degree: the angle gauge is used to detect the degree of surface grinding.
The test of surface roughness of grinding: it is allowed to compare with other grinding surfaces that are measured.
Detection of 6.1.9 spring perpendicularity:
The detection of the parallelism between the two ends of the 6.1.10 spring:
6.1.11 spring straightness measurement:
Measurement of geometry size of 6.2 stretch spring
The content of tensile spring geometry includes: material diameter, free length, spring diameter, total number of circles, relative angle of two hook rings, location of the center of the hook ring and the center line of the spring, the length of the spring hook ring part, etc. The first 4 tests refer to the detection method of the compression spring, and the following methods are mainly introduced.
The detection of the relative angle of the 6.2.1 spring two hook and the ring:
Position degree of center line and axis line of 6.2.2 spring hook and ring:
Detection of the length of 6.2.3 spring hook and ring: test with vernier caliper.
6.2.4 spring total loop number detection: the total number of rings as a reference value, when the position of the hook and ring is required, should ensure the position of the hook and ring. The detection method is visual.
Detection of geometry size of 6.3 torsion spring
The dimension of torsion spring includes: material diameter, free length, free angle, spring diameter, total circle number, torsion arm length, torsion arm bending angle and so on.
6.3.1 spring free length detection: the free length of the dense coil spring is not examined. The detection method refers to the compression spring.
6.3.2 spring free angle detection:
A spring with characteristic requirements is not examined at a free angle.
The free angle of the spring can be detected by the angle gauge, the tool microscope, or the special measure.
The angle gauge is to adjust the angle of the angle by adjusting the angle of the angle and reclosing the two arms. The angle of the angle is the free angle of the spring.
The detection of the length of the 6.3.3 spring torsion arm is detected by the vernier depth ruler or the vernier caliper.
The detection of the flexural degree of the 6.3.4 spring torsion arm: reference to the free angle of the spring.
6.3.5 test method for measuring the diameter of the torsion spring, the diameter of the material and the number of the total rings.

7. Detection of the characteristics of cylindrical helical spring
7.1 detection of the characteristics of tension and compression springs
7.1.1The characteristics of spring tension and compression spring should meet: in the specified height (or length) of the load between the spring deformation should be under test load deformation of 20% ~ 80% grade accuracy requirements, spring deformation under load specified height should be more than 4mm; the characteristics of assessment the special needs of the stiffness, the deformation should be under test load deformation from 30% to 70%.
7.1.2Detection of load and stiffness of spring
7.2 Detection of the characteristics of  torsion springs
7.3 the test of the standing and permanent deformation of a cylindrical helical spring

8, detection of fatigue property and relaxation rate of spring
8.1 spring fatigue performance testing requirements:
8.2 spring fatigue test specimen
The 8.2.1 specimen shall be manufactured in accordance with the technical documents approved by the prescribed procedure, and the test shall be qualified.
8.2.2 samples should be extracted from the same batch of products randomly and independently. The quantity is carried out according to the relevant regulations.
8.3 spring fatigue testing machine
The error of the 8.3.1 test machine should be in accordance with the relevant regulations.
The frequency of the 8.3.2 test machine should be adjustable in a certain range to meet the requirements of different tests.
The functions of 8.3.3 test machine usually include: test time or frequency preset function, automatic timing or counting function, test amplitude display or control function, automatic stop function.
Evaluation of 8.4 spring fatigue test results
8.4.1 fatigue life determination: under a given failure condition, the maximum cycle number of spring is reached, that is, the fatigue life of the spring.
8.4.2 fatigue life verification: after a given cycle test, if the spring does not fail, it is proved that the test is passed.
8.4.3 reliability verification: according to the given reliability target value, the suitable sample number is determined according to the regulations. N is determined according to the required failure mode under the specified test conditions and requirements. If the number of qualifications obtained is greater than the minimum qualified number r required, the verification test is passed and vice versa is not passed.
8.4.4 The relaxation rate of the spring:
The relaxation rate after the fatigue test should be within the range specified in the pattern.