In response to the suspension point defects of European wire rope electric hoists, systematic improvements need to be made from five aspects: design optimization, installation specifications, material upgrades, regular inspections, and intelligent monitoring. The specific solutions are as follows:

1、 Design optimization: Strengthen the load-bearing chain structure

Upgrade the diameter of the pin shaft: Increase the diameter of the pin shaft for fixing the steel wire rope at the front end of the suspension crossbeam from 18mm to above 20mm, ensuring that its load-bearing capacity forms a more reasonable strength gradient with the work platform pin shaft (16mm). For example, if the original design pin material is 45 # steel, it can be upgraded to 40Cr alloy steel to improve tensile strength and wear resistance.

Unified bolt specifications: Replace the two M14 bolts at the connection between the front crossbeam and the front bracket with M16 or M18 high-strength bolts, and adopt a double nut anti loosening design to reduce the problem of single bolt stress caused by insufficient machining accuracy. At the same time, optimize the bolt layout to make the force more uniform.

Improvement of hanger support structure: Upgrade the hanger support bolts from ordinary M14 to high-strength M16 bolts with anti loosening devices, or use welded support structures to eliminate the risk of bolt loosening. For example, using Q345B steel plate welded hangers and adding triangular reinforcement bars to improve overall rigidity.

2、 Installation specifications: Strictly control the construction process

Bolt pre tightening force control: Use a torque wrench to apply pre tightening force to M16 and above bolts, such as controlling the pre tightening force of M16 bolts within the range of 180-220N · m to ensure a secure connection. At the same time, record the pre tightening force data of each bolt and establish an installation file.

Installation inspection of pin shaft: Before installation, check the surface of the pin shaft for defects such as cracks and scratches. After installation, measure the gap between it and the hole wall to ensure that the gap is ≤ 0.1mm. Regularly conduct non-destructive testing (such as magnetic particle testing) on the pin shaft to detect early cracks in a timely manner.

Suspension mechanism leveling: Use a spirit level to adjust the height of the front and rear supports, ensuring that the horizontal error of the front and rear beams is ≤ 1/500. After adjustment, fix the adjusting rod with a locking nut to prevent loosening during operation. For example, on a 10 meter long front beam, the horizontal error should be ≤ 20mm.

3、 Material upgrade: Select high-strength components

Replacement of shaft material: Replace ordinary carbon steel shaft with 40Cr or 42CrMo alloy steel shaft to improve tensile strength and fatigue life. For example, the tensile strength of 40Cr pin shaft can reach 980MPa, which is more than 1.5 times that of ordinary carbon steel.

Bolt material optimization: Use 8.8 or 10.9 grade high-strength bolts instead of ordinary 4.8 grade bolts. For example, the tensile strength of M16 grade 8.8 bolts is 800 MPa, which is twice that of grade 4.8 bolts (400 MPa).

Strengthening of hanger structure: Upgrade the hanger material from Q235 steel to Q345B steel and increase the wall thickness (such as from 6mm to 8mm). At the same time, optimize the shape of the hanger to reduce stress concentration points.

4、 Regular testing: Establish a maintenance mechanism

Bolt condition inspection: Check the bolts monthly for looseness, rust, or breakage, and use a torque wrench to verify the pre tightening force. For example, for M16 bolts, tighten them again every 3 months to ensure that the pre tightening force is within the specified range.

Measurement of pin wear: Use a vernier caliper to measure the diameter of the pin every six months. If the wear exceeds 5% of the original diameter, replace it immediately. At the same time, check whether there are defects such as indentation and cracks on the surface of the pin shaft.

Structural deformation monitoring: Use a total station to measure the bending deformation of the front and rear beams every year. If the deformation exceeds 1/1000 of the beam length (such as a 10 meter beam deformation>10mm), it needs to be corrected or replaced.

5、 Intelligent monitoring: introducing early warning system

Bolt pre tightening force monitoring: Install intelligent torque sensors on key bolts to monitor changes in pre tightening force in real time. When the pre tightening force decreases by more than 20%, the system will automatically sound an alarm and prompt for tightening.

Stress analysis of the pin shaft: Stick strain gauges on the surface of the pin shaft and analyze the stress distribution through a data acquisition system. If the stress exceeds 70% of the material's yield strength, the system will issue a warning and the pin shaft needs to be checked or the load adjusted.

Suspension mechanism tilt monitoring: Install tilt sensors on the front and rear brackets to monitor the tilt angle of the suspension mechanism in real time. If the tilt angle exceeds 1 ° (i.e. the anti overturning safety factor K is close to 2), the system will automatically stop running to prevent overturning.

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment