Service HotlineSubject content and scope of application This technical requirement specifies the technical requirements for the manufacture, installation and inspection of high-strength bolted joints of mobile machinery and equipment. Contents not specified in this technical requirement shall be implemented in accordance with relevant national standards. This technical requirement applies to mobile machinery steel structures that require high-strength bolted connections. This technical requirement applies to quality control and construction methods for in-plant and on-site installations. 2. Joint surface treatment 2.1 For friction type high-strength bolt connections, the joint surfaces at the joints are required to be in close contact with each other and have a sufficient friction coefficient. When the design drawing does not specify the treatment requirements for the joint surface, the treatment shall be carried out according to the following regulations: sandblasting or shot blasting the joint surface of high-strength bolts, remove impurities such as rust and oil stains on the surface, and reach the Sa2.5 standard , the roughness is 50 ~ 75μm, and the friction coefficient shall not be lower than 0.40. When there are regulations in the drawings, follow the regulations in the drawings. 2.2 The friction surface of the treated high-strength bolt connection should take protective measures to prevent contamination with dirt and oil. It is strictly forbidden to make any marks on the friction surface of the high-strength bolt connection. During storage in the factory, or during transportation, to the installation site, special precautions should be taken to prevent contamination of the connection surfaces. The installation unit should pay special attention to protecting the cleanliness and friction surface characteristics of the connecting plate of the high-strength bolt and the connecting surface of the parent body. It is not allowed to use a grinder to grind the connecting surface of the connecting plate and the connecting surface of the parent body. 3 Inspection of the anti-slip coefficient of the friction surface of high-strength bolts The inspection of the anti-slip coefficient should be based on the steel structure manufacturing batch, and each 2000t of a single project is regarded as a manufacturing batch, and those less than 2000t are regarded as a batch. When two or more surface treatment processes are selected, each surface treatment process needs to be inspected. Each batch of three groups of specimens. If the connection is diffused to an external enterprise, each corresponding enterprise shall conduct an anti-slip coefficient test. 3.1 The test piece used for the anti-slip coefficient test should be processed by the factory or the diffusion enterprise. The test piece and the representative steel structure member should be of the same material, produced in the same batch, using the same friction surface treatment process and have the same surface state. And use the same batch of high-strength bolt connection pairs of the same performance level and store them under the same environmental conditions. The anti-slip coefficient test is carried out according to the test method of GB50205 Code for Acceptance of Construction Quality of Steel Structure Engineering. 3.2 The minimum value of the anti-slip coefficient inspection must be equal to or greater than the design specified value. When the above specified values are not met, the friction surface of the component should be reprocessed. The friction surface of the treated component is re-inspected. 4. Connection and installation of friction type high-strength bolts for steel structures 4.1 Preparations before installation 4.2 Select qualified bolts, nuts and washers. The guarantee period for the torque coefficient of the connecting pair is six months from the date of delivery. 4.3 Bolts, nuts and washers in the following cases are unqualified products and are prohibited from being used. a. The source (manufacturer) is unknown; b. The mechanical properties are unknown; c. The torque coefficient k is unknown; d. Defective; e. No performance test report attached; f. Mixed with other batches of bolts; g. Bolts with insufficient length, that is, the bolt head does not show the end face of the nut after tightening. Generally, the length of the end face of the nut to be taken out is 2 to 3 threads. h. The torque coefficient of the connecting pair exceeds the warranty period. Special attention should be paid to waterproofing during transportation and storage. 4.4 Before the construction of the large hexagonal head high-strength bolts, the torque coefficient of the high-strength bolt connection pair should be re-inspected according to the factory approval. Each batch of 8 sets should be re-inspected. Less than or equal to 0.010. The re-inspection method of the torque coefficient shall be carried out in accordance with the provisions of GB50205 Code for Acceptance of Construction Quality of Steel Structure Engineering. The installation of high-strength bolts should be carried out within a short period of time after the test.
The purpose of Guangdong Yueluo Hardware Industry Co., Ltd. is to overcome the above shortcomings and provide a limit screw. The technical scheme of Guangdong Yueluo Hardware Industry Co., Ltd. is realized in the following way. Its structure is composed of screws, hexagonal copper posts and limit necks. The left end of the limit neck is open, the hexagonal copper column is communicated with the inside of the limit neck, and the inside is provided with screw threads. The design length of the screw thread in the hexagonal copper column is 1/3-2/3 of its own length. The advantages of Guangdong Yueluo Hardware Industry Co., Ltd. are (7), which can effectively prevent the problem of poor memory contact caused by the increase of the deformation of the motherboard due to the warping and deformation of the motherboard during installation and fixation, and can effectively control the amount of deformation effect.
The process of removing iron oxide plate from cold heading steel wire rod is stripping and dephosphorization. There are two methods: mechanical dephosphorization and chemical pickling. Replacing the chemical pickling process of wire rod with mechanical phosphorus removal not only improves productivity, but also reduces environmental pollution. This phosphorus removal process includes bending method (the round wheel with triangular grooves is commonly used to repeatedly bend the wire rod), spray nine method, etc. The phosphorus removal effect is good, but the residual iron and phosphorus cannot be removed (the removal rate of iron oxide scale is 97%) ), especially when the iron oxide scale is very sticky, therefore, mechanical phosphorus removal is affected by iron scale thickness, structure and stress state. Carbon steel wire rods used for low strength fasteners (less than or equal to 6.8) High-strength bolts (greater than or equal to grade 8.8) use wire rods to remove all iron oxide scales after mechanical dephosphorization, and then go through a chemical pickling process for compound dephosphorization. For low carbon steel wire rods, the iron sheets left by mechanical dephosphorization are likely to cause uneven wear of grain draft. When the grain draft hole adheres to the iron sheet when the wire rod rubs against the external temperature, the surface of the wire rod produces longitudinal grain marks. More than 95% are caused by scratches on the surface of the steel wire during the drawing process. Therefore, the mechanical phosphorus removal method is not suitable for high-speed drawing.
In order to achieve this purpose, the rivet nut is cold extruded from low carbon steel, the brim is cold forged, the deformed skirt is extruded in the die, and the threaded hole is extruded at the lower end of the deformed skirt. It is characterized in that it consists of a brim, a deformed skirt and a threaded hole. There are fish teeth below the brim; the outer side of the lower end of the threaded hole has a lead angle; the cross section of the thread on the inner wall of the threaded hole is an isosceles trapezoid, and the upper bottom of the trapezoid is a concave arc. Thus, the riveted object is tightly connected with the rivet nut.
The main technical problem solved by Guangdong Yueluo Hardware Industry Co., Ltd. is to provide a fixing screw for installation, so as to provide a PCB fixing method with convenient operation, reliable connection and low production cost. In order to solve the above-mentioned technical problems, a technical solution adopted by Guangdong Yueluo Hardware Industry Co., Ltd. is to provide a fixing screw for installation, which includes a screw body, the axial surface of the screw body is formed with extended screw teeth, and the screw body is The bottom has a hemispherical screw tail, the top of the screw body is provided with a screw head, and the upper surface of the screw head is provided with a slot. According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the screw body is composed of an upper tapered rod and a lower cylindrical screw rod, and the tapered rod is an inverted cone. According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the diameter of the circular upper surface of the inverted cone of the taper rod is equal to the diameter of the screw mounting hole. According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the screw further has a washer, the washer is arranged between the screw head and the screw body, and the washer is a cylinder. According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the lower surface of the cylindrical washer has a plurality of teeth, and the teeth are along the edge of the connection between the upper surface of the inverted cone of the tapered rod and the washer Ribs formed by extending outwards. According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the teeth of the washer are in contact with and pressed against the PCB board. According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the protruding strip is an arc-shaped or straight-shaped structure. According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the notch opened on the upper surface of the screw head is a slot. [0018] According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the notch provided on the upper surface of the screw head is a cross groove. According to a preferred embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the fixing screw is integrally formed with conductive material. Compared with the existing technology, the fixing screws for installation designed by Guangdong Yueluo Hardware Industry Co., Ltd. can not only ensure the accuracy of the PCB installation position, but also can be installed easily and reliably, which greatly reduces the manufacturing cost and waste of metal materials.
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