Abstract
The welding deformation and cracking of hydraulic support have always been an important issue that impacts product quality and performance in the industry. In order to quantify the deformation of the welding seam of the reverse four-bar linkage hydraulic support under loading conditions, a real-time weld monitoring system based on sensitive fiber Bragg grating sensors is designed. The strength test and the cycle life test of the top coal caving reverse four-link support with four typical eccentric loads were conducted, respectively. The strength test results prove that the fiber Bragg grating sensor is accurate enough to measure welding deformation of hydraulic support; the measurement resolution reaches 0.1 μm. The eccentric load experiment produces the reverse four-bar torsion, especially when the top beam is at a low position; the maximum deformation of the weld is 100 μm. In the cycle test, a phenomenon has been captured, i.e., the welds present a baseline shift along with the cyclic load and even jump. It indicates that the hydraulic support changes from one stable state to another stable state. This work not only provides a feasible solution for welding deformation monitoring but also provides a possibility for the whole life cycle monitoring of hydraulic supports.
Highlights
According to the latest World Energy Data Statistics Report for 2019 provided by the British company BP, the total annual global power generation in 2019 was 27004.7 TWh
The underground coal mines are mainly mined in the form of comprehensive mechanized coal mining, using highly automated “three fully mechanized mining machines,” namely, shearer, scraper conveyors, and hydraulic supports [1]. e hydraulic support plays a vital role in supporting the roof of the coal mining face and protecting the equipment and workers of the coal mining face [2]
Λa is the constant nominal period of refractive index modulation; after the light passes through the fiber Bragg grating (FBG), a certain bandwidth λa corresponding to Λa is reflected. e rest of the light continues propagating forward, the reflected light is separated from the incident light by the optical coupler, and the light sensor is used to monitor the reflected light
Summary
According to the latest World Energy Data Statistics Report for 2019 provided by the British company BP, the total annual global power generation in 2019 was 27004.7 TWh. The underground coal mines are mainly mined in the form of comprehensive mechanized coal mining, using highly automated “three fully mechanized mining machines,” namely, shearer, scraper conveyors, and hydraulic supports [1]. E top coal transition support is one of the most important support equipment for comprehensive mechanized top coal mining. E mechanical characteristics of the reverse four-bar linkage mechanism of the transition support are better than those of the positive four-bar linkage transition support, and it is more suitable for top coal mining. Most of the top coal mining is faced with unfavourable situations such as large thickness drop and complex geological conditions, making it difficult for traditional simulation to obtain force characteristics close to the actual application. According to the actual application of the reverse four-bar linkage structure of the top coal caving transition support underground, the weld seam of the four-bar linkage structure
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