(1) friction coefficient: where, F is the force that causes the specimen to generate initial slip measured in anti-slip test, nf is the number of friction surfaces, and is the sum of measured pre-tension values of tightening high-strength bolts corresponding to F.
(2) torque coefficient: where d is the nominal diameter (mm) of high-strength bolts, M is the applied torque value (N M), and P is the pre-tightening force of bolts. 10.9 high strength large hexagon bolt connection must ensure that the average torque coefficient K is 0.110 ~ 0.150. The standard deviation shall be less than or equal to 0.010.
(3) initial torque: in order to reduce the impact of steel plate deformation during bolt fastening, secondary tightening can be used to reduce the interaction between successive tightening bolts. The first screw of high strength bolt is the initial screw, and its axial force should reach 60% ~ 80% of the standard axial force.
(4) final twist torque: the torque used for the final fastening of high-strength bolts is the final twist torque. Considering the loss of various prestresses, the final torque is generally 5% ~ 10% higher than that calculated theoretically according to the design pretension.
Steel structure cleaning - steel structure shot blasting machine
Cleaning process is controlled by electric adjustable speed roller conveyer to send steel structures or steel to a cleaning machine room body mass ejection area, its around the surface hit by powerful dense projectile from different coordinates azimuth and friction, make its scale, rust layer and its dirt falls off quickly, steel surface was bright and clean surface with certain roughness, in cleaning up outdoor roller on both sides of the import and export unloading workpieces. The pellets and rust dust falling on the steel are purged by the purging device, and the scattered pellets and dust mixture are transported by the recovery spiral to the chamber funnel and vertically and horizontally to the spiral conveyor to collect in the lower part of the elevator and then to the separator on the upper part of the machine. The separated pure pellets fall into the separator hopper for the use of shot blasting cycle. During shot blasting, dust is generated and sent to the dust removal system by the exhaust pipe. After purification, the net gas is discharged into the atmosphere, and the granular dust is captured and collected.
Ii. Main composition
Steel structure shot blasting machine
Steel structure shot blasting machine
1. Clean up the room
The cleaning chamber is a large capacity cavity plate type box-type welding structure, and the inner wall of the chamber is lined with ZGMn13 wear-resistant protective plate. The cleaning operation is carried out in the sealed cavity.
2. Conveying roller table
It is divided into indoor conveying roller table and loading and unloading section conveying roller table.
The indoor roller table is covered with high chromium wear-resisting sheath and limit ring. The high chromium wear-resisting sheath is used to protect the roller table and withstand the impact of projectiles. The limit ring can make the workpiece run according to the predetermined position to prevent deviation and cause accidents.
3. The elevator
It is mainly composed of upper and lower drive, cylinder, belt and hopper.
The bottom same diameter belt pulley on the hoist adopts a polygonal structure composed of rib plate, wheel plate and wheel hub, so as to enhance the friction force, avoid skidding and extend the service life of the belt.
The shell of the hoist is bent and formed. The cover plate on the shell of the hoist can be opened to repair and replace the hopper and lap belt. Opening the cover plate on the lower casing of the hoist can remove the obstruction of the bottom projectile.
Adjust the pull plate driven by bolts on both sides of the lifting machine shell to move up and down to maintain the tightness of the lifting belt.
The upper and lower belt pulley adopts outer spherical ball bearing with square seat, which can be automatically adjusted when it is impacted by vibration and has good tightness.
4. The separator
The screw conveyor is mainly composed of reducer motor, screw shaft and screw housing.
The outer spherical ball bearing with square seat is adopted, which can be automatically adjusted when it is impacted by vibration and has good tightness.
6. Pellet delivery pipeline
The shot delivery pipeline has dual shot control functions, and a gate is set above each brake tube to cut off the projectile from the separator, so as to facilitate the maintenance of respective shot blasting devices. The size of gate opening can adjust the flow rate of the projectile, and the number of gate opening and closing can also be arbitrarily combined according to the specification of the cleaning workpiece, so as to save energy, reduce the wear of the machine and ensure to meet the production needs.
7. Shot blasting machine
Single disc shot blasting machine has become the perfect high level shot blasting machine in China. It is mainly composed of rotating mechanism, impeller, casing, directional sleeve, shot splitting wheel and guard plate, etc., among which the impeller is forged with Cr40 material and the blade, directional sleeve, shot splitting wheel and guard plate are all made of high chromium.
8. Purging device
This device adopts high-pressure fan, and sets multiple sets of elastic blow nozzles with different angles in the auxiliary chamber of the chamber body, to blow and clean the remaining projectiles on the workpiece surface.
9. Inlet and outlet seals
The workpiece inlet and outlet sealing devices are made of rubber spring steel plate, in order to prevent in blasting, the projectile spillage cleaning outdoor, in the workpiece inlet and outlet are provided with multiple ways to strengthen the sealing, its characteristics are strong elasticity, long life, good sealing effect.
10. Dust removal system
Cloth bag filter
The dust removal system is mainly composed of bag-type dust collector, fan and dust removal pipe. Dust removal efficiency up to 99.5%.
11. Electrical control
The electrical control system USES the conventional control to realize the control of the whole machine, using high-quality electrical components produced at home and abroad, with the advantages of high reliability and convenient maintenance, etc., the main circuit by the miniature circuit breaker and thermal relay to realize the short circuit, phase, overload protection of the motor. It is also equipped with several emergency stop switches to facilitate emergency shutdown and prevent the expansion of accidents.
Safety protection switch is set on each access door of cleaning room and cleaning room. When any access door is opened, shot blasting machine cannot start.
3. To summarize
Through shot blasting machine is mainly used in the metal structure, machine tool bed, steel (cast iron) products, network frame, construction machinery and bridge manufacturing industry.
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