Caving caused casualties, damage to equipment, production suspension and other accidents, still one coal mine production of major disasters, many special geo-technical environments need to develop special roof support security measures, and relevant cadres to go to the site command. In soft coal, rock formations and quicksand and geological fracture zones, it is more likely that large-scale leakage will occur when the fault zone is driven into the mine shaft. For example, in July 2001, a mine in Baishan City, Jilin Province, suffered a roof collapse in the construction of the wellbore. When the roof fell, the roof collapsed and collapsed, and five workers on the spot were buried. During the rescue process, the roof collapse and water collapse occurred again, and 13 miners and 3 rescuers were all buried. After the accident, the local provinces and municipalities and the Tonghua Mining Bureau formulated an active and safe accident rescue plan. After 16 days, all 21 people were buried. The direct cause of the accident: violation of the rules to deal with the top, after the burial accident, and blindly violated the regulations to cause the roof and collapse, resulting in an accident. It can be seen that it is very necessary to prevent the roof from falling and paying attention to the roof leakage.
Second, the prevention and control of leakage accidents in the wells
Due to the soft dip angle of the coal seam in the mine roadway, the direct roof is abnormally broken. If the working face support fails or cannot be supported, a local leakage occurs, and the broken roof may leak from this position under the action of gravity. , causing a leak in the work surface.
(1) Geological prediction and prediction of mine roadway engineering
1. Geological prediction and prediction before construction of wells and roads, using geological exploration, existing wells and roadways to expose relevant geological data, predicting geological fracture zones, large faults, subsided columns, back-slanting extrusions, etc. that may be encountered during construction Construction, location of soft and thick coal seams, and scope of influence, in order to develop targeted safety technical measures.
2. Special geological technical environment observation during the construction process of the roadway engineering, the roof cracks of the roadway engineering are developed, the geological fracture zone appears, and the fault layer is filled with powder or mud. The fault planes are relatively smooth, between the upper and lower plates. There is almost no cohesive force in the rock. Especially when the fault plane becomes a water-conducting fissure, it is separated from each other, leaking coal, and dripping water. It is a possible sign of a roof, and it must be decisively predicted and prevented. ()
(II) Safety technical measures to prevent leakage and roof collapse in the shaft
1. Select appropriate support, the roadway bracket should have sufficient support strength to counter the surrounding rock pressure. The amount of deformation that the bracket can withstand should be compatible with the possible deformation of the surrounding rock during use of the roadway.
2. As far as possible, the bracket and the surrounding rock are co-bearing. When selecting the bracket, use the bracket with the initial supporting force as much as possible. The construction of the bracket should be strictly in accordance with the quality requirements of the process, and pay special attention to the problem of the back and the back of the gang, and eliminate the empty top and the empty between the bracket and the surrounding rock. Help the phenomenon.
3. Where the roof is empty due to the failure of the support, the roof should be protected before the new support. When replacing the bracket with the roadway, you must first support the new bracket and then remove the old bracket. Supports within 10 meters of the face of the tunneling face must be reinforced before blasting, and the brackets that have collapsed or collapsed by blasting must be repaired first.
4. Improve the stability of the roadway support in the roadway where the roof is prone to collapse. The struts can be connected and fixed between the brackets of the roadway to increase the stability of the shed to prevent it from being pushed down. In the inclined roadway, the bracket is more likely to be pushed down, and the strength and density of the rear tensioning member of the bracket should be appropriately increased, and there are safety measures for preventing the meteorite, the material, the bracket from rolling off and the bracket falling down.
(III) Construction of the roadway ahead of the support The application of the roadway engineering project encounters an abnormally broken roof, and the soft coal seam needs to continue to move forward. The key to prevent roof fall is to control the roof. In this regard, in recent years, we have applied advanced support in the practice of coal mine roadway construction to reduce roofing and the effect is obvious. Use the advanced drill pipe at the top of Yingtoujing Lane to advance the roof. Drill the eye in the direction of the roadway, leave the drill pipe, and several drill pipes form the canal and the surrounding rock to jointly carry the control to the top plate. The length of the drill pipe is 3 to 5 meters, the distance between the parallel drill pipes is 15-20cm, and the number of drill pipe is selected according to the width of the roadway section. Generally, the common section of the 6.1m2 is 1.7 meters wide, and the diameter of the drill pipe is 6-8. Controlled at 5 ° ~ 8 °. In order to ensure that the distribution of the drill pipe is balanced and parallel, in principle, the long drill collar is not used once, but after a short drill pipe is used for about 1.5 meters, the long drill pipe is gradually deepened to the final long drill pipe. Whether the drill pipe is reused or recycled must be determined according to the safety and recovery cost of the project. The roof of the broken roof is long and can be reused and superimposed on each other. For example: Fenghai Coal Mine 307 mining area +15C9N, two over thick coal seams, 301 mining area -60C9S over-crushing belt adopt this method, the tunnel construction passed smoothly.
Common tool:
1. Air leg rock drill YZ-24 type.
2. Drill specifications: Ф42mm, Ф38mm.
3. Drill pipe: B22-1.5 B22-3.5.
(4) The arrangement of the blasthole and the amount of charge are reasonable, so as to avoid collapse of the bracket
Third, after the roof of the shaft is damaged
(1) The principle of controlling the expansion of the roof to prevent and weaken the damage of large areas is to change the physical and mechanical properties of the rock mass to reduce the ceiling and the area of ​​the roof, reduce the height of the roof and reduce the air discharge speed. The first is to use the pit% test-test-large% wood top to control the roof to fall; the second is to spray the slurry, which can weaken the roof and enlarge the cracks in the rock layer to weaken the surface.
(2) Partially-circumferential concrete filling wells have large roof-topping space with a height of 5-6 meters. It is difficult and impossible to control the roof. The concrete arching is over the roof area. It is difficult to operate according to the formal procedures. dig. According to the space, it is necessary to construct the arch or the wall to partially pour the concrete. The surrounding rock near the roof area is often stressed and broken. In order to ensure that the masonry of the new construction around the irrigation has a certain initial pressure resistance, the rail arch or the steel is generally used as the skeleton. Finally, the incomplete parts of the masonry are gradually trimmed and perfected. Fenghai Mine 307 mining area - 130 Shimen roofing treatment, Jiafu Mine 206 mining area track Shangshan-20 å²” mouth roof are adopted this plan to cross the roof area.
Investment casting technical flow process
The silica sol casting process also called precision investment casting process. It is a less cutting or no cutting casting process. It is an excellent technique in foundry industry. Its application is very extensive. It not only applicable to various types, various kinds of alloy and casting, and produce the casting dimension accuracy and surface quality is higher than other casting method, Even other casting method can not do the complex, high temperature resistant, not easy machining castings, all can be used for investment precision casting process.
The investment casting process, it is a process that use fusible materials make soluble model, and coated with several layers of tailor-made refractory coating on the surface, after drying and hardening become a whole shell, melt the shell model by steam or hot water. Then put the shells in the sand, filling dry sand in all round and modeling. Finally roasting it based on high-temperature in the furnace, the shell after roasting, and getting the casting part after pouring molten metal.
The investment casting process can produce High precision dimensional parts, generally can reach to CT4-6(sand casting is CT10-13, die casting is CT5-7). Due to the complexity of investment casting process, there are many factors influencing the casting dimension accuracy. Such as shrinkage of mold material, deformation of the casting, Shell heating and cooling line quantity change in the process, alloy shrinkage and deformation of castings in the solidification process. The surface finish of investment castings is higher than the ordinary casting, can reach to Ra1.6~3.2.
The greatest advantages of investment casting is casting parts have high dimensional accuracy and surface finish, so it can reduce the mechanical processing. The another advantage of investment casting method is that it can cast all kinds of alloy and complex casting part, special casting high temperature alloy casting part.
The precision of the Steel Casting Part: ±0.15mm~
Smoothness of surface of rough part: Ra6.4;
Shrinkage rate of steel investment casting products: 0.6%;
Material wastage rate: 5%;
General stainless steel casting part machining allowance: 0.7mm;
Surface preparation methods: Sand blasted, Shot blasting, Powder coating, Painting, Plating, Electrophoresis, Polishing.
Our company's production equipment and management system
CNC machining center: 8 sets AIGEMA A-8;
CNC lathe machine: 6 Guangzhou Machines and 7 Shenyang Machines;
Work days of one week: From Monday to Saturday;
Shift work: 2 shift per day;
Working hours: From AM 8:00 to PM 5:00;
2D and 3D drawing Software: AutoCAD, UG, Pro/E, SolidWorks 2013;
QC control: New type NANO CMM, FPI M5000 desktop metal analyzer, Easson projector, Mechanical properties tester.
The steel casting process and machining equipment:
Steel Casting Part
Stainless Steel Lost Wax Casting, Steel Casting Part, Steel Investment Casting Part, Steel Silica Sol Casting Part
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