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Original Title: Drilling Processing (I) 1. Drilling type and its application The drilling processing method for steel structure engineering mainly uses drill bit processing, shearing processing and gas cutting processing, and its application range is divided by the hole diameter and the plate thickness of the part, which is roughly as shown in Figure 1. In addition, although the drilling using laser processing and electric ion processing has been reviewed recently, it has not yet reached the stage of formal practical application due to the limitation of applicable board thickness. In addition, the processing method used to distinguish the purpose and use of drilling is shown in Table 1. 2. Drill hole with drill bit The drilling method using a drill bit is suitable for the NC machining method, and the progress in the past ten years is very striking. As is well known, the drill machining method is a kind of cutting machining, which is a deformation of a tool machining method for cutting a surface with a material harder than the material to be machined. The tool is processed into a spiral shape as a drill, and the drill is pressurized and rotated to perform a circular cutting process. The principle is shown in fig. 2. Because there is little thermal change in the base material during machining and there is little hardening of the machined surface, excellent characteristics of high hole accuracy are used in a wide range of fields, and also become the mainstream of drilling machining methods in steel skeleton engineering. Expand the full text a. Type of drill bit Table 2 shows the types and characteristics of the drill bits used in the drill bit drilling method, and Table 3 shows the oil (water) feeding method of cutting oil or cutting water. b. Grinding of drill bit (Figure 3) The dimensional accuracy of the hole diameter is affected by the grinding of the drill bit, and if it is poor, not only the hole diameter will become larger, but also it will not become a true circle. When grinding by hand, be sure to use the residual material for trial drilling to confirm the accuracy of the hole diameter. Therefore, it is desirable to use a grinder for the grinding of the drill. The standard of the front end angle of the drill bit is 118 118. On the other hand, in the case of using the so-called straight grinding with the front end angle of 150 150 to 180 180, compared with the standard angle, it is possible to drill at the correct position at the beginning of drilling, and there is an advantage that there is less burr in the feed of the drill before the hole is penetrated. However, in-line lapping is not suitable for the drilling of overlapping plates or the deep hole processing of thick plates. In addition, the cutting speed at the central part of the drill is extremely small, so that the drill cannot cut, and the cutting material is forcibly crushed to advance. Thining of the drill tip is performed for the purpose of sharpening the center portion and discharging the chips well, and as shown in fig. 4, there are S-type, X-type, N-type, and their combinations, among which the S-type is widely used. c. Drilling method (1) Drilling period The occurrence of shrinkage and deformation cause by welding in that weld structure portion is unavoidable, and therefore, the drilling time in the manufacturing process has a great influence on the accuracy of the finis product. In particular, the dimensional accuracy between the holes in the construction site joint of the column or beam immediately affects the finishing accuracy of the steel skeleton. Therefore, the drilling period of the member, except for an additional plate or a joint plate, is 1. Make a sample of the hole on the material sheet in advance, and then make a sample confirmation after the assembly, welding and deformation correction, and then make a drilling process. 2. Drill the hole at one end of the material sheet first, and then drill the hole at the other end after assembly, welding, Borehole Drill Bits , and deformation correction. 3. After the welding and deformation correction of the parts, the two ends shall be finished, and the drilling shall be carried out on the basis of the finished surface. 4. The shrinkage caused by welding and deformation correction of the material sheet is predicted first, and the shrinkage is added to the material for drilling processing and assembly. Among them, 1-3 is implemented when it is difficult to predict the welding shrinkage due to the complex structure, and the operation efficiency of the reversal, sample dropping, drilling and processing of the parts is lower than "." Can accurately predict that amount of shrinkage, can reduce the cost, and is an excellent proces method. Therefore, it is necessary to collect shrinkage data frequently, and after full review, it should be collated into processing data for proper storage. In addition, the NC drilling machine is widely used recently, and its specialty is that the drilling accuracy is good, while the general joint hole of parts is "" as the mainstream. (2) Drilling The application of NC drill machines, which do not require sample drop, has been increasing in order to prevent that decrease in accuracy and efficiency caused by the use of sample drop for each hole or the drilling of holes one by one in accordance with the sample drop, for the drilling of parts such as holes in a field joint, which are required to have dimensional accuracy relative to each other at the hole position. For the drilling of the small and medium plates such as the spliced plate or the connecting plate which are not operated by the NC machine, it is desired to use a correctly manufactured template for the overlapping drilling, or to use a multi-spindle drilling machine, a profile drilling machine, etc. If you want to use the template repeatedly, it is better to embed it in the template. Quenched sleeve. The pressing force and the number of revolutions of the drill during drilling are different depending on the material of the material to be processed, the type of the drill, the cooling method, etc., and it is necessary to select the correct conditions in advance. In order to increase the drilling speed, drilling with unreasonable pressure or number of revolutions will not only cause large burrs or poor hole diameter accuracy, but also cause mechanical failure and safety problems, which should be avoided. (3) Treatment after drilling The burr of the hole on the joint surface must be removed. Especially in the high tension bolt friction joint, it is to make the parts close to each other, and the friction force is used to ensure the endurance, so the close joint between the parts is particularly important, and there must be no foreign matter mixed in. In addition, the rust, black skin, oil, paint, etc. on the joint surface shall be completely removed. On the other hand, there are the following three methods for the treatment of the friction surface of the high tension bolt joint, the drilling period, and the removal of burrs. 1. Drill holes in the black skin state, remove the burrs, and then use sandblasting to ensure that the roughness of the friction surface is more than 50 μmRy. 2. Similarly, after drilling in the black skin state,dth button bits, remove the burrs with a grinder and treat the friction surface to make red rust. 3. Sand blasting is used before drilling to ensure that the roughness of the friction surface is more than 50 μmRy. At this time, in ord to treat that burrs and the like generate during the drilling, a method of removing only the burr is required if the friction surface around the hole is not rusted due to adverse effects caused by a commonly used surface grinder. To be continued. Return to Sohu to see more Responsible Editor:. wt-dthtools.com
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