1. Overview and role of mining high-strength compact chains
According to the actual use of the ring chain in the coal mine, change the geometric shape and related dimensions of the traditional mining ring chain, and design a new chain ring shape and chain structure form. The compact chain consists of a vertical ring and a flat ring. The size and type of the flat ring are the same as those of the mining circular chain. The two sides of the vertical ring are flat and the outer width is smaller than that of the mining high-strength circular chain. The change of the vertical ring shape is greatly reduced. The stress concentration on the chain ring increases the life of the chain. Therefore, without changing the size of the conveying chute, the power of the conveyor can be upgraded and the conveying capacity of the conveyor can be improved. At the same time, since the straight arm part of the vertical ring is in surface contact with the middle plate of the conveyor chute, the contact characteristics of the traditional circular chain line are changed, and the wear resistance is increased.
Second, the compact chain market analysis
With the government's rectification and technical investment in coal mining, the popularity of fully mechanized mining continues to increase. Since large-scale high-strength circular chain is a product with large equipment investment and high technology content, nearly 80% of large-scale high-strength compact chains are produced. The market share depends on imports, but with the introduction of imported equipment, the continuous improvement of localization rate, the continuous improvement of quality and technology, and the advantage of price, it is only a matter of time to replace imports.
3. There are two main types of compact chain production processes:
The first type: vertical ring is extruded and blanked → single vertical ring braided chain → vertical ring shot blasting → vertical ring welding → vertical ring heating → vertical ring extrusion molding → flat ring and vertical ring braided together → shot blasting → Flat ring welding→stretching to specified size→heat treatment→pre-stretching and shaping→inspection→pairing→warehousing
The second type: the vertical ring is forged and blanked → the flat ring and the vertical ring are braided together → shot blasting → flat ring welding → one stretch to the specified size → heat treatment → secondary pre-stretching and shaping → inspection → pairing → The high-strength compact chain for storage mining is a new type of product. It is different from the traditional chain mainly in that it is connected by vertical rings and flat rings. Therefore, the knitting method in the production process is completely different from the previous chain knitting.
The first production process is mainly used by domestic ring chain manufacturers. The vertical ring is formed by hydraulic presses. The main representative manufacturers are Jiangsu Green Machinery Co., Ltd., Tiandi Benniu and German Tiller Company. The main production process is that the vertical ring is formed by die forging equipment. The main representative manufacturers are Zhangjiakou Parsons Coal Machinery Co., Ltd., Jiangsu Green Machinery Co., Ltd., Germany Tiller and Poland Huaxing and other companies. From the above two production processes, specially designed chain braiding equipment must be used, and the forming of each chain link can only be completed by two stations, so the braiding process method and tooling mold must be redesigned. In addition, whether it is a forged vertical ring or an extruded chain ring, it is a chain ring with a variable cross-section. The welding ring and the geometric shape and cross-sectional shape are different, so the amount of deformation is also different, which must be determined through a large number of process tests. The process size requirements can ensure that the standard requirements are met, but at the same time, the instability of the pitch is also a fundamental problem of the current compact ring. In particular, the second production process, which is different from the traditional chain link due to the forging of the vertical ring, is still lacking in the selection of raw materials and the accuracy of dimensional progress.
The third type is to directly forge the bar material. Some domestic manufacturers have introduced the production technology of Poland Huaxing. First, the two sides of the bar material and the ZTE position are forged into a flat shape by die forging, and then knitted together by a chain braiding machine, and then welded.
The development of the mining high-strength compact ring is based on the improvement of the mining high-strength circular ring chain, and the chain ring size, shape and chain structure have been optimized. These improvements and optimizations are based on the results of the chain force analysis and under the condition that the power of coal mining equipment needs to be increased and the underground space of the coal mine is limited.
The increase in the specifications of mining high-strength compact chains and circular chain chains, the changes in structural forms and the improvement in mechanical performance requirements have prompted the rapid development of chain-making equipment and process technology in China.