What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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.
The tooling for screw standard parts provided by Yueluo Guangdong Yueluo Hardware Industry Co., Ltd. mainly solves the problems of low manual operation matching efficiency, wrong specifications of screw standard parts, and easy falling of screw standard parts into the product when assembling screws in the prior art. . The specific technical solutions of Guangdong Yueluo Hardware Industry Co., Ltd. are as follows. The screw standard parts supporting tooling includes a stud sleeve hole plate, a gasket sleeve hole plate and a nut sleeve hole plate with matching structure; the stud sleeve hole plate There is at least one stud hole matching with the assembled stud structure, at least one gasket hole matching with the assembled gasket structure is arranged on the gasket sleeve hole plate, and the nut sleeve hole plate is provided with at least one gasket hole matching with the assembled gasket structure. At least one nut hole matched with the assembled nut structure; the number of stud holes, gasket holes and nut holes are equal. The above-mentioned stud sleeve hole plate is provided with a positioning device, and the gasket sleeve hole plate is provided with a matching positioning hole; or the gasket sleeve hole plate is provided with a positioning device, and the stud sleeve hole plate is provided with a matching positioning hole. The above stud holes are through holes; the nut holes are blind holes. Forty to one hundred and fifty stud holes are arranged on the stud sleeve hole plate. The above-mentioned positioning device is a positioning plate and/or a positioning column. The advantage of Guangdong Yueluo Hardware Industry Co., Ltd. is that the matching tooling for screw standard parts improves the matching quality of screw standard parts, effectively prevents screw standard parts from falling into the product easily and screw specifications are wrong; it simplifies the matching difficulty of screw standard parts and improves assembly efficiency. . The screw standard parts supporting tooling can be processed differently according to different screw standard parts specifications, and the applicability is very wide.
Reference standard GB 90 Fastener acceptance inspection, marking and packaging GB 196 Basic dimensions of ordinary threads (1～600mm in diameter) GB 197 Tolerance and fit of ordinary threads (1～355mm in diameter) GB 230 Test method for Rockwell hardness of metals GB 699 High-quality carbon Plain structural steel technical conditions GB 1237 Marking method of fasteners GB 5267 Electroplating layer of threaded fasteners GB6394 Determination of average grain size of metals
Bolt: 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. [1] Stud: A type of fastener that has no head and only has external threads on both ends. When connecting, one end of it must be screwed into the part with the internal threaded hole, the other end must pass through the part with the through hole, and then the nut must be screwed on, even if the two parts are tightly connected as a whole. This form of connection is called a stud connection, which is also a detachable connection. It is mainly used for occasions where one of the connected parts is thick, requires a compact structure, or is not suitable for bolt connection due to frequent disassembly. [1] Screw: It is also a type of fastener consisting of a head and a screw. It can be divided into three categories according to the purpose: machine screws, set screws and special-purpose screws. Machine screws are mainly used for a fastened connection between a part with a fixed threaded hole and a part with a through hole, without the need for nut matching (this connection form is called screw connection, which is also a detachable connection; it can also be Cooperate with the nut, it is used for the fast connection between two parts with through holes.) The set screw is mainly used to fix the relative position between the two parts. Special purpose screws, such as eyebolts, are used for hoisting parts. [1] Nuts: with internal threaded holes, generally in the shape of a flat hexagonal column, but also in a flat square column or flat cylindrical shape, with bolts, studs or machine screws, used to fasten and connect two parts, make it a whole. [1] 5. Self-tapping screw: Similar to machine screw, but the thread on the screw is a special thread for self-tapping screw. It is used to fasten and connect two thin metal components to make them a whole. Small holes need to be made in advance on the components. Due to the high hardness of this kind of screw, it can be directly screwed into the hole of the component, so that the Forming a corresponding internal thread [1] 6. Wood screw: It is also similar to a machine screw, but the thread on the screw is a special thread for wood screws, which can be directly screwed into wooden components (or parts) to connect a band through The metal (or non-metallic) part of the hole is fastened to a wooden member. This connection is also a detachable connection. [1] 7. Washers: A type of fastener with an oblate annular shape. It is placed between the supporting surface of the bolt, screw or nut and the surface of the connecting part, which increases the contact surface area of the connected parts, reduces the pressure per unit area and protects the surface of the connected parts from damage; another type of elastic washer, It can also play a role in preventing the nut from loosening. [1] 8. Retaining ring: It is installed in the shaft groove or shaft hole groove of the machine and equipment, and plays the role of preventing the parts on the shaft or the hole from moving left and right. [1] 9. Pins: mainly used for positioning the left and right parts, and some are also used for connecting parts, fixing parts, transmitting power or locking fasteners. [1] 10. Rivet: A type of fastener consisting of a head and a shank, which is used to fasten and connect two parts (or components) with holes to make them a whole. This form of connection is called rivet connection, or riveting for short. It is a non-removable link. Because if the two parts joined together are separated, the rivets on the parts must be broken. [1] 11. Components and connection pairs: Assemblies are a type of fasteners supplied in combination, such as a combination of a certain machine screw (or bolt, self-supplied screw) and a flat washer (or spring washer, lock washer); Connection pair refers to a type of fastener that is supplied by a combination of special bolts, nuts and washers, such as high-strength hexagon head bolt connection pairs for steel structures. [1] 12. Welding nail: a heterogeneous fastener composed of a nail rod and a nail head (or no nail head), which is fixed to a part (or component) by welding, so as to be connected with other parts. .
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
