Specification for high strength bolts of steel grid

Type and specification

The thread specification of high-strength bolt of grid structure is m12-m64, which can be seen in details: high strength bolt for steel grid bolt ball joint GB / t16939-1997, of which the bolt below M20 is mostly used in decoration grid structure. Because of the fixed interrelation in the joint structure, the screw length of each specification of high-strength bolt of grid structure is also fixed. For details, please refer to relevant data. Because the high-strength bolt and sleeve of the grid structure are matched, the specification of the bolt is determined by checking the pressure of the sleeve when designing the joint.

Quality inspection and acceptance

The main basis for the inspection and acceptance of high-strength bolts of grid structure is code for acceptance of construction quality of steel structures (GB50205-2001) and jg12-1999 standard for inspection and acceptance of steel grid structure.

In code for acceptance of construction quality of steel structure engineering (GB50205-2001), the high-strength bolts of grid structure are used as standard parts for site inspection and acceptance. See article 4.4 for details. In addition, article 4.4.5 has special instructions for "surface hardness test".

According to jg12-1999 inspection and acceptance standard for steel grid structure, the main inspection items for high-strength bolts are hardness, crack and length.

Solid shape

The shape is as shown in the figure. The special place is that there is a chute on the screw rod, and there is a part of deep groove near the head. That is the place where the fastening screw (PIN) on the matching "sleeve" (nut without grain) is embedded. Because of the insertion of the pin, when installing, turning the wrench can drive the bolt to screw into the bolt ball. At the same time, the pin slides in the chute. When the bolt is screwed in place, the fastening screw is just in the deep groove At this time, tighten the fastening screw to make it fall into the deep groove, so as to achieve the effect of retaining and anti loosening.