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The transmission thread of the currently used gas cylinder charging valve largely follows the design scheme of mature models, employing the same ordinary triangular thread as the fastening thread. Ordinary thread connections offer good self-locking performance and are commonly used for fastening connections or fine-pitch adjustment screws. Due to inherent issues with the thread profile's applicability, a problem of thread stripping in the transmission thread occurred during the standard life test of batch-produced products. To address this issue, a thread improvement scheme was proposed. Through research on the improved design of the transmission thread for the gas cylinder charging valve, the original triangular thread was replaced with a trapezoidal thread. The improved trapezoidal thread exhibits a lower stress level and a larger margin relative to the allowable stress, demonstrating a good improvement effect. Four 3J1 studs successfully passed the 1 000-cycle high-pressure limit life test under pressure. The service life of the thread pair increased from less than 250 cycles to 1 000 cycles, verifying the feasibility of the trapezoidal thread scheme and improving the service life of the thread pair.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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