Diaphragm Spring Introduction
Clutch Disc Spring, Technical Conditions
I. Scope
This standard specifies the structural type, technical requirements, testing methods, and inspection rules for diaphragm springs.
This standard applies to diaphragm spring for mechanical clutch (hereinafter referred to as diaphragm spring), and the diaphragm spring in the damper is also applicable for reference.
Section II: Normative References
The following documents are essential for the application of this document. For referenced documents with dates, only the version with the date applies to this document. For referenced documents without dates, the latest version (including all amendments) applies to this document.
Method for Determining the Decarburization Layer Depth of Steel According to GB/T 224
GB/T 230.1 Metal Materials Rockwell Hardness Test Part 1: Test Method (Scales A, B, C, D, E, F, G, H, K, N, T)
GB/T 1222 Spring Steel
GB/T 1800.2-2009 Product Geometric Technical Specification (GPS) Limits and Fits Part 2: Standard Tolerance Grades and Limits of Fit Tables for Holes and Shafts
GB/T 1972 Disc Spring
GB/T 3279 Hot-Rolled Steel Sheets for Springs
YB/T 5058 Cold-Rolled Spring Steel, Tool Steel Strip
Section 3: Parameter Name, Code, and Unit
Parameter names, codes, and units are listed in Table 1.
Table 1: Parameter Name, Code, and Unit
Parameter Name | Code | Unit |
Diaphragm Spring Outer Diameter | D | mm |
Diaphragm Spring Inner Diameter | d | |
Inner diameter of the enclosed ring section in diaphragm springs | Dm | |
Diaphragm spring thickness | t | |
Inner cone height of the sealed ring section in diaphragm spring | y | |
Free height of the diaphragm spring | H。 | |
Large deformation of diaphragm spring (inner cone height) | Smax(Smax=Ho-t) | |
Separation refers to the minor diameter width | b1 | |
Separation refers to the width of the window slot. | b2 | |
Inner radius of the sealed ring in diaphragm spring | r | |
Outer radius of the sealed ring section in diaphragm spring | R | |
Deformation amount | S | mm |
Deformation amount of the sealed ring section in the diaphragm spring | Is | |
Deformation amount of the tongue part in the diaphragm spring | S2 | |
Separation Index (number of tongue blades) | Z | |
Workload | F | N |
IV. Structural Style
4.1Diaphragm Spring Structure Type
The diaphragm spring structure is as shown in Figure 1.
Figure 1: Diaphragm Spring
Six: Technical Requirements
6.1 Materials
6.1.1 Material
The material for diaphragm springs is generally 50CrVA or 60Si2MnA, with its chemical composition and physical properties complying with the GB/T 1222 specifications; if other materials are used, they can be agreed upon by both the supplier and the buyer.
6.1.2 Requirements
The steel strip used for diaphragm springs should comply with YB/T 5058 specifications, or with GB/T 3279 specifications.
6.1.3 Inspection
Materials must be accompanied by a quality certificate from the material manufacturer and must pass a re-inspection before they can be used.
6.2 Dimensional Tolerance Limits
6.2.1 Thickness
The allowable deviation of the thickness "t" of the diaphragm spring should comply with the specifications in Table 2. In case of special requirements, the allowable deviation of the thickness "t" shall be agreed upon by both the supplier and the buyer.
Table 2: Maximum Deviation of Thickness tOff (unit: millimeters)
Thickness t | Ultimate deviation |
0.5~1.0 | +0.02 -0.03 |
>1.0~2.3 | +0.03 -0.05 |
>2.3~3.0 | +0.04 -0.05 |
>3.0~4.0 | ±0.05 |
6.2.2 Free Height
The allowable deviation of the free height of the diaphragm spring should comply with the specifications in Table 3. The free height can be appropriately adjusted during manufacturing while ensuring the characteristic requirements, but the tolerance value remains unchanged.。
Table 3: Limiting Deviation of Free Height (in millimeters)
Free Height H. | Ultimate deviation |
<10 | +0.20 -0.10 |
>10~20 | +0.20 -0.20 |
>20~50 | +0.10 -0.50 |
>50~100 | ±1.50 |
6.2.3 Diameter
The inner and outer diameter tolerances of the diaphragm spring are in accordance with the H13 and h13 grades specified in GB/T 1800.2-2009.
6.3 Flatness
The sealed portion of the diaphragm spring should have a flatness tolerance of 0.25mm on the bottom surface, and the arc length of the non-contact surface should not exceed 1/3 of the circumference.
6.4 Coaxiality
The coaxial tolerance of the diaphragm spring should comply with the specifications in Table 4.
Table 4: Axial Tolerance (in millimeters)
Outer Diameter: D | 30~50 | >50~125 | >125~250 | >250~500 |
Axial tolerance | 0.2 | 0.25 | 0.3 | 0.4 |
6.5 Load Characteristic Limit Deviation
The membrane spring working area's characteristics are required based on user needs, but the load deviation at the working point is within the range of -10% to 20%.
6.6 Heat Treatment
Diaphragm springs must be quenched and tempered, and the quenching process should not exceed two times.
6.7 Hardness
The hardness value of the sealed part of the spring diaphragm after tempering should be selected within the range of 71.5HRA to 76.8HRA, and the allowable tolerance for the hardness of a single spring diaphragm is ±2HRA.
For the upper surface of the separated tip section (with a maximum diameter of ø70mm), the hardness value should be above 79HRA, with a depth greater than 0.5mm. A hardness transition zone is permissible between the separated tip section and the sealed part, but the minimum hardness within the transition zone should not be less than 68.9HRA.
6.8 Carbon Deposition Depth
The heat-treated diaphragm spring should have a single-sided decarburization layer depth not exceeding 1% of its thickness, and the maximum depth should not be more than 0.05mm.
6.9 High-pressure treatment
The diaphragm spring should undergo high-pressure treatment, which is performed by compressing the diaphragm spring using a load not less than twice the value of s = 0.75h for a duration of at least 12 hours, or by short-term compression, with at least 5 compression cycles.
6.10 Surface Quality
The surface of the diaphragm spring should be free from burrs, cracks, and any defects harmful to its use.
6.11 Surface Corrosion Treatment
Diaphragm springs are typically dipped in rust preventive oil after shot blasting, and can also be treated with oxidation, phosphatizing, electro-phoresis, etc., as per customer requirements. Diaphragm springs are not suitable for electroplating treatment.
6.12 Fatigue Life
When fatigue life requirements are specified, the number of fatigue life cycles can be agreed upon by both parties.
Section 7: Test Methods
7.1 Dimension and Positional Tolerances
7.1.1 Thickness
The thickness of the diaphragm spring should be measured at least at three points along the circumference, both inside and outside the diameter of the diaphragm spring, using a micrometer, and the maximum value should be taken.
7.1.2 Diameter
The diameter of the diaphragm spring is measured using a micrometer caliper with a least count of less than or equal to 0.02mm. At least three measurements are taken at different positions along the circumference, with the outer diameter being the largest value and the inner diameter being the smallest value.
7.1.3 Free Height
The free height of the diaphragm spring should be measured on a grade 2 precision flat plate with a depth micrometer having a graduation value of less than or equal to 0.02mm. At least 3 measurements should be taken at different positions around the circumference, and the maximum value should be taken.
7.1.4 Flatness
Place the diaphragm spring on a secondary precision flat plate, measure the diaphragm spring plane clearance at a load of 2% s = 0.75ho using a feeler gauge, and take the largest clearance value. The maximum load should not exceed 300N, as shown in Figure 3.
Figure 3: Diagram of Flatness
7.1.5 Coaxiality
Place the diaphragm spring on a secondary precision flat plate, measure its diaphragm spring width with a caliper with a least count of 0.02mm or less, as shown in Figure 4. Measure at least three positions, and calculate the difference between the maximum measured value and the theoretical value. This difference is the coaxiality error.
Axial alignment error can also be agreed upon by both parties for measurement using a converted tooling.
Figure 4: Coaxiality Error Measurement
7.2 Load Characteristics
The load of the diaphragm spring is tested on a machine with accuracy not less than 1%, and its load is measured when loaded to the required deformation amount. Lubricant must be used during the test. The hardness of the upper and lower plates measuring the load characteristics of the diaphragm spring must be above 52HRC, and the surface roughness Rz must be less than 1.6μm.
7.3 Hardness
The hardness test of diaphragm springs is conducted according to GB/T 230.1 specifications. The indentation should be made between the outer diameter of the diaphragm spring and the window, with 4 points per piece, the first point being disregarded, and the average of the last three points taken. The separation finger hardness test should be performed within a range of 2mm to 10mm below the finger tip (refer to Figure 5 of this standard); the method is the same as above.
