According to the force of the connection, it is divided into ordinary and hinged holes. According to the shape of the head: there are hexagonal head, round head, square head, countersunk head and so on. Among them, the hexagonal head is the most commonly used. Generally, countersunk heads are used where connections are required. The English name of the riding bolt is U-bolt. It is a non-standard part. The shape is U-shaped, so it is also called a U-bolt. There are threads on both ends that can be combined with nuts. It is mainly used to fix tubular objects such as water pipes or sheets such as automobile plates. Springs are called riding bolts because of the way they fix things like a person rides a horse. According to the length of the thread, it is divided into two categories: full thread and non-full thread. According to the thread type, it is divided into two types: coarse thread and fine thread. The coarse thread type is not displayed in the bolt mark. The bolts are divided into eight grades: 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9 according to their performance grades. Among them, the bolts above grade 8.8 (including grade 8.8) are made of low-carbon alloy steel or medium-carbon steel and are heat-treated (quenched). + Tempering), commonly known as high-strength bolts, and below grade 8.8 (excluding 8.8) are commonly known as ordinary bolts. Ordinary bolts can be divided into three grades: A, B, and C according to the production accuracy. Grades A and B are refined bolts, and grade C is rough bolts. For connecting bolts for steel structures, unless otherwise specified, they are generally ordinary rough grade C bolts. There are differences in the processing methods of different grades. Usually the corresponding processing methods are as follows: ① The bolts of grade A and B bolts are processed by lathes, with smooth surfaces and accurate dimensions. High, rarely used; ②C-grade bolts are made of unmachined round steel, the size is not accurate enough, and its material property grade is 4.6 or 4.8. The deformation is large during shear connection, but the installation is convenient and the production cost is low. It is mostly used for tensile connection or temporary fixation during installation.
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.
Nuts are parts that tightly connect mechanical equipment. Through the inner threads, nuts and bolts of the same specification can be connected together. For example, M4-P0.7 nuts can only be connected with M4-P0.7 series bolts (in the nut). Among them, M4 means the inner diameter of the nut is about 4mm, and 0.7 means that the distance between the two threads is 0.7mm); the same is true for American products, for example, a 1/4-20 nut can only be matched with a 1/4-20 screw ( A 1/4 finger nut has an inner diameter of about 0.25 inches, and 20 fingers have 20 teeth in each inch).
In the riveting operation, the rivet used is composed of a mandrel and a deformed collar. When in use, a through hole is drilled on the two components to be connected, and then the head of the rivet is passed through the through hole and clamped by a rivet. The tail of the rivet will break the rivet, the head of the rivet and the deformed collar remain in the through hole, and the whole riveting process is completed. The existing pull rivets have the following shortcomings: first, the parts where the pull rivet and the two components are connected cannot be completely and tightly fitted, which meets the requirements of non-sealing for parts that have waterproof and leak-proof requirements; second, the existing pull rivets The separation groove of the rivet mandrel is close to its head. When the mandrel is broken by the rivet during the riveting process, basically only the head of the mandrel remains in the deformation collar, and the connection of the two components depends on the deformation of the collar. Under the action of compressive stress, the inside of the deformed collar becomes hollow due to the breaking of the mandrel, and cannot bear large shear stress.
rivet assembly device is provided with a base, the middle of the base is provided with a vertical groove, the bottom wall of the vertical groove extends forward and a horizontal convex block is suspended; the top surface of the convex block is fixed with a vertical rivet Needle and a guide column, the column body of the guide column is covered with a return spring; a downwardly open sliding block is mounted on the convex block, and the upper ends of the rivet needle and the guide column respectively protrude into the sliding block on the top wall of the sliding block. In the riveting pin hole and the guide hole, the inner wall of the riveting pin hole is provided with a large upper and a lower small horizontal step; the upper part of the bottom wall of the vertical groove is provided with a guiding limit rib. Guangdong Yueluo Hardware Industrial Co., Ltd. sets the rivet needle under the workpiece, and uses the upper die punch to press down the workpiece, and the rivet needle completes the operation of the rivet, omitting the operator to turn over and carry the rivet terminal board, thus effectively avoiding the rivet from The phenomenon that the rivet hole comes out. In addition, during operation, the workpiece is placed on the top surface of the slider, and the workpiece guide limit ribs and guide columns are used as shafts and radial limiters respectively. The riveting quality is good, and the purpose of saving time and labor and high efficiency is achieved.
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