GB/T 12730-2018 in English

1. Background and significance of standard revision

Narrow V-belt is a core component in the transmission system, and its performance directly affects the transmission efficiency and equipment life. The formulation of GB/T 12730—2018 standard aims to meet the needs of high-speed and large-power transmission, replace the outdated GB/T 12730—2008 version, and make important adjustments in technical requirements.

Main revisions include:

• Optimization of dimensional performance requirements and test methods
• Delete the requirements for cord bonding strength in physical properties
• Improvement of fatigue performance indicators

2. Structure and classification of narrow V-belts

Narrow V-belts are divided into wrapped and cut-edge types according to their structure, and the latter is further divided into three types: ordinary cut-edge, toothed cut-edge and bottom rubber and cloth cut-edge. Its basic components include wrapping cloth, top cloth, top rubber, buffer rubber, tensile body, bottom rubber, etc. (see Figure 1).

The model system of narrow V-belts is as follows:

• SPZ, SPA, SPB, SPC
• 9N, 15N, 25N
• Toothed models: XPZ, XPA, XPB, XPC, 9NX, 15NX, 25NX

3. Technical requirements and test methods

Appearance quality: The defect limits of edge-wrapped and edge-cut narrow V-belts are strictly regulated (see Table 1).

Dimension measurement: The reference width system and effective width system are applicable to different scenarios, and the specific requirements are in accordance with GB/T 11544.

Physical performance test: Tensile strength and reference force elongation are in accordance with GB/T 3686 (Table 2).

Fatigue performance test: A new Appendix B specifies the test method for a two-wheel test machine, requiring the test to be stopped when the termination condition is reached or the slip rate reaches 8%.

4. Implementation suggestions

Choose a suitable narrow V-belt model: According to the transmission power and speed requirements, give priority to the corresponding model (such as SPZ or 15N).

Strictly abide by the inspection rules: The frequency of factory inspection and type inspection must meet the standard requirements to ensure product quality.

Proper storage and transportation: Avoid high temperature and humid environment to prevent mechanical damage. It is recommended to use professional packaging and pay attention to the storage temperature range (-18°C to 40°C).