What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In recent years, a spring pin connection structure has appeared in the connection between the beam and the column: a pin hole is arranged on the column, and a spring pin is arranged at the end of the beam. When installing, the spring pin can be inserted into the pin hole. However, when more than two spring pins are used, if the spring pins are slightly deviated from the pin holes, it is difficult to spring into the pin holes; and if the pin holes are drilled larger, although the spring pins are easy to spring in, it will cause the spring pins to spring into the pin holes. Looseness with pin hole. In addition, after the spring pin is used for a long time, the spring is easily corroded and fractured, which also leads to structural instability and difficulty in disassembling the beam.
Subject 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.
Bolt: A mechanical part, a cylindrical threaded fastener with a nut. A type of fastener consisting of a head and a screw (a cylinder with an external thread), which needs to be matched with a nut to fasten and connect two parts with through holes. This form of connection is called a bolted connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.
The production process of rivet nuts is basically similar to that of other screws. It's just that the screws are punched out with a screw pier, and the nuts are punched out with a nut pier. Introduce the production process of rivet nuts. 1. First, it is necessary to determine what material and material the rivet nut is, so that we can use what material to produce and what material to use. Knowing what materials and materials are used, we can buy screw wires. 2. Determine the size and length of the rivet nut. This is the best way to use a large screw wire. 3. After determining the material, material, size and type, we need to see if it is a commonly used rivet nut. If so, there must be a corresponding mold in the factory. If not, it is non-standard, then we have to order molds. 4. After everything is ready for production, it is necessary to use the nut machine to punch out the shape of the rivet nut, that is, the appearance. 5. After the pier is punched out, use the machine for tapping the nut teeth to tap it. 6. After the thread is tapped, electroplating is performed. The stainless steel rivet nut does not need electroplating, it only needs to be cleaned. If you want to electroplate other colors, you have to take it to a professional electroplating manufacturer for electroplating treatment.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
