Machining process of high strength bolt for steel space frame bolted spherical joint

Abstract

The invention discloses a machining process of a high strength bolt for a steel space frame bolted spherical joint, which relates to a machining process of a high strength connecting piece. A bolt is manufactured by the processes of high frequency induced current hot forging, cold extrusion and the like. The machining process is provided on the basis of a patent application of which the patent application number is 200810020089.2, the hot forging of the machining process adopts high frequency induction heating, the frequency is controlled to be between 20,000 and 50,000 Hz, and by using the advantages of high heating speed, uniform heating and the like of the high frequency induction heating, the surface of a workpiece obtains a uniform structure and performance from the core to the surface, the heating uniformity of the workpiece is improved, a better crystalline phase structure can be obtained, and the high strength bolt with better performance is obtained; and simultaneously, in a softening annealing step, a large amount of carbon-rich substances are put into a softening furnace to snatch oxygen atoms in the furnace at a high temperature, reduce the oxidizing atmosphere in the furnace, reduce the oxidative decarburization degree of the workpiece, and further ensure the quality of the workpiece.

Description

technical field [0001] The invention relates to a processing technology of a high-strength connecting piece, in particular to a processing technology of a high-strength bolt used for a steel grid frame bolt ball joint. Background technique [0002] High-strength bolts for steel grid bolt ball joints are commonly used fasteners in the machinery industry. The current processing method is generally formed by turning, and its strength is often difficult to guarantee. When the tensile strength exceeds a certain value, in the gap concentration Places such as the transition between the rod and the head or the root of the thread are likely to cause delayed fracture and fatigue fracture, which will seriously affect the quality of the project. In severe cases, it will cause safety accidents due to insufficient connection strength. Therefore, traditional high-strength The production process of bolts should be studied and improved to efficiently carry out mass production under the premi...

AI Technical Summary

Problems solved by technology

[0002] High-strength bolts for steel grid bolt ball joints are commonly used fasteners in the machinery industry. The current processing method is generally formed by turning, and its strength is often difficult to guarantee. When the tensile strength exceeds a certain value, in the gap concentration Places such as the transition between the rod and the head or the root of the thread are likely to cause delayed fracture and fatigue fracture, which will seriously affect the quality of the project. In severe cases, it will cause safety accidents due to insufficient connection strength. Therefore, traditional high-strength Research and improve the production process of bolts, so as to efficiently carry out mass production under the premise of ensuring its quality, and meet the society's extensive needs for high-strength bolts for steel grid bolt ball joints

Therefore, the patent application No. 200810020089.2 provides a processing technology for high-strength large hexagonal head bolts for steel structures. The surface or internal fibrous structure, at the same time, salt bath quenching and nitrate tempering are used in the heat treatment, which reduces the degree of oxidation and decarburization on the surface of the workpiece, and further ensures the quality of the bolts, but in the hot forging step, use a hot forging furnace Heating, there are slow heating speed and uneven heating, resulting in the defects of overheating in some parts of the workpiece and insufficient heating in some places, which may easily cause defects such as skinning, slag inclusion, cracking, and cracking in the workpiece; at the same time, in the softening step , due to the serious oxidation atmosphere in the softening furnace, the oxidation and decarburization layer of the workpiece is serious, which also affects the quality of the workpiece