JB/T 7590-2005

Who´s who in the Zoo?

Have a look at the wave spring washer below. This shows the same wave spring from the 4 points of the compass, or rotated by 90° degrees each time. So, how many waves does it have? Not so easy to tell necessarily, and one can understand how confusion might arise.

In general we describe a wave by its height (amplitude), frequency and wavelength.

• The amplitude is what we provide as the Free Height - L₀ and Height at Load H_L
• The frequency is implicit in the D_e and D_i dimensions
• The wavelength is the distance between successive crests of a wave - So now Fig 1.1, specifically Frames 1 and 3, most definitely show a single wavelength from that perspective.

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JB/T 7590-2005

Technical specifications for steel wave springs for motors

Here we will introduce you to the specific content of JB/T 7590-2005 steel wave spring technical conditions for motors, which is a revision of JB/T 7590-1994 "Technical Conditions for Steel Wave Springs for Motors".

• This standard was first published in December 1994, and this is the first revision.
• This standard replaces JB/T 7590-1994.
• This standard is under the jurisdiction of the National Rotating Electrical Machine Standardization Technical Committee (SAC/TC26).
• The main drafters of this standard: Huang Liming, Luo Xiaochen, Zhao Zhiyan.

1 Scope

This standard specifies the structural type, technical requirements, test methods, inspection rules, marking and packaging requirements for steel wave springs for motors (hereinafter referred to as wave springs).

This standard applies to the basic series of small and medium-sized asynchronous motors and their derivative series, and also applies to steel wave springs used in other equipment that require axial preload.

2 Normative reference documents

The provisions in the following documents become provisions of this standard through reference in this standard. For dated reference documents, all subsequent amendments (excluding corrigenda) or revisions do not apply to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. . For undated referenced documents, the latest edition applies to this standard. ▶ GB/T 90.1-2002 Fasteners Acceptance Inspection (idt ISO 3269: 2000) ▶ GB/T 191-2000 Pictorial marking for packaging, storage and transportation (eqv ISO 780: 1997) ▶ GB 755-2000 Rotating electrical machines Ratings and performance (idt IEC 60034-1: 1996) ▶ GB/T 2828.1-2003 Enumeration sampling inspection procedures Part 1: Batch-by-batch inspection sampling plan retrieved by acceptance quality limit (AQL) (ISO 2859-1: 1999, IDT) GB/T 2829-2002 Periodic inspection counting sampling procedures and tables (applicable to inspection of process stability) ▶ YB／T 5058-1993 Spring steel, tool steel cold rolled strip 3 structural type A wave spring is an elastic element with several wavy peaks and valleys on a metal sheet ring. Its shape is as shown below: wave spring structural type 4 Technical requirements 4.1 Wave springs should comply with the requirements of this standard and be manufactured according to drawings and technical documents approved through prescribed procedures. 4.2 The on-site operating environment of the wave spring should comply with the regulations of GB755. 4.3 The heat treatment and surface treatment of wave springs shall be in accordance with the requirements of Table 1, and the material properties shall comply with the requirements of YB/T 5058. Table 1 Material Heat Treatment Surface Treatment Type Brand number Standard Spring Steel 65Mn YB/T 5058 Quenched and tempered, 45HRC～52HRC(process reference) Oxidation 4.4 The surface of the wave spring should be smooth, free of rust, burrs, cracks and other defects, and the oxide layer should be uniform. 4.5 The wave curve of the wave spring should be approximately sinusoidal, the cross-section should not be curved, and each wave crest should be evenly distributed along the circumference. 4.6 The shape and installation dimensions of the wave spring should comply with the requirements in Table 2. Table 2 4.7 The elastic force of the wave spring at the specified test height should comply with the requirements of the corresponding level in Table 3. Table 3 4.8 After the elastic test of the wave spring, its elastic force should not be less than 90% of Fmin. 4.9 The wave spring is not allowed to break after passing the toughness test. 5 Test methods 5.1 The apparent quality of wave springs is judged by visual inspection and hand feel. 5.2 The shape and installation dimensions of the wave spring are measured with a vernier caliper and a micrometer with a gauge. The inner and outer diameters are measured at two points perpendicular to each other, and the average value is taken. The free height should be measured one by one at the middle diameter of each wave peak, and the average value is taken. . 5.3 Elasticity test Place the wave spring between the two parallel plates of the testing machine, gradually apply the load until the distance between the two parallel plates reaches the test height specified in Table 3, and measure the elastic force at this time. The equipment used in the elastic test should eliminate the systematic errors caused by zero drift and select appropriate accuracy. 5.4 Elasticity test Place the wave spring that has passed the elastic force test between the two parallel plates of the testing machine, gradually increase the load so that the distance between the two parallel plates reaches H mm/3, and maintain the load for 24 hours. Release the load and perform the spring test again. 5.5 Toughness test Bend the wave trough of the wave spring around a ø8mm round rod to cover 1/4 of its circumference, and visually inspect its surface. 6 Inspection rules 6.1 Wave springs must pass the inspection before leaving the factory. 6.2 Wave spring inspection is divided into factory inspection and type inspection. 6.2.1 The factory inspection items of wave springs are: a) Apparent quality (4.4); b) Appearance and installation dimensions (4.6); c) Elasticity test (4.7). 6.2.2 The wave spring type inspection items are: a) Apparent quality (4.4); b) Appearance and installation dimensions (4.6); c) Elasticity test (4.7); d) Elasticity test (4.8); e) Toughness test (4.9). 6.3 Type inspection should be carried out in any of the following situations: a) During the first trial production or small batch trial production by the manufacturer after identification and finalization; b) When there are major changes in structure, materials and processes; c) When there is a big difference between the factory inspection results and the previous type inspection results; d) The wave springs produced in batches shall be randomly tested regularly, once a year. 6.4 Sampling methods and judgment rules 6.4.1 Classification of inspection items It is divided into two types of inspection items: A and B. Class A inspection items include elasticity test, elasticity test and toughness test; Class B inspection items include apparent quality, appearance and installation dimensions. 6.4.2 Factory inspection According to GB/T 2828.1, one-time sampling for normal inspection, Class A inspection items AQL = 1.5, IL = II; Class B inspection items AQL = 2.5, IL = II. Factory inspection can also adopt the fixed sample inspection method of GB/T 90.1. AQL for Class A inspection items = 1.5 and AQL for Class B inspection items = 2.5. The arbitration shall be carried out according to GB/T 2828.1. 6.4.3 Type inspection Sampling according to GB/T 2829, judgment level DL=II, 16 pieces are selected from each item, the same sample is allowed to be used for several tests in the order of 5.1~5.5, Class A inspection item RQL=30, A. =3,R. =4; Class B inspection items RQL=50, Ac=5, R=6. 7 Logo and packaging 7.1 Logo It is composed of specifications plus elasticity grade suffix. When the elasticity grade is M level, the grade suffix can be omitted. Example: A wave spring with specification D90 and elasticity level M is marked D90-M or D90. 7.2 The wave spring should be rust-proofed before packaging. The outer packaging should be in corrugated cartons, and it should be ensured that under normal storage and transportation conditions, it should not be rusted or damaged due to poor packaging within six months from the date of shipment. 7.3 There should be a product inspection certificate in each packaging box. 7.4 The words and signs on the outer wall of the packaging box should be clear and neat, with the following contents: a) Name of manufacturer; b) Name of receiving unit: c) Wave spring model and product number: d) Product quantity; e) The net weight of the wave spring and the gross weight of the box; f) Overall dimensions of the packaging box; g) Date of production; h) The words "Afraid of Rain" should be marked on the appropriate position of the packaging box, and the graphics should comply with the requirements of GB/T 191.

Adding Waves - So what?

The addition of waves to the profile of the washer spring, and hence the addition of more contact points between the washer spring and the relevant surfaces, has some interesting dynamics to it.

Useful Equations

The equations used for the calculations of Load, Deflection and Stress are derived from those for a simple beam and have the application of some corrective factors based on empirical measurements and experience.
These equations for loads & stresses, are not precise solutions, but they do provide very useful engineering estimates. As a measure of usefulness, they are more accurate and useful than any of the forecasting models Economists use to explain Recessions, but not nearly as accurate as Cosmologists employ to calculate the Hubble Constant.
Some skepticism should be expected if Forces are provided in Newtons with decimal places.
We can now derive various useful metrics, such as:

1. Required Material Thickness - t, to support a Load:
   
   


2. Deflection - s, expected from a Load:
   
   


3. Induced stress - σ, created by a Load:
   
   


4. Deflection - s, expected at stress threshold:
   
   

Typically, the Load Characteristic Curve for a Wave Washer Spring is only linear between 20% and 60% of s/h₀, after which the Load/Deflection relationship becomes digressive (i.e. The relationship between compression and load is no longer linear, in fact, the delta in Load/Force as the final 25% of the Free Travel is compressed yields none or very little delta in Load) - this can be very useful. The waves are formed during manufacture when the metal is in its annealed state in order to achieve the peaks and troughs that make the wave. As a good rule of thumb, the ratio of the Mean Diameter (D) to the Radial width of the spring (b) should be between 7 and 16. This dimensional relationship achieves a balance between load-carrying ability and flexibility.