Convex Roller Telescopic Boom Plate Deformation
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Solution Overview
Problem
The existing telescopic booms in working vehicles and cranes face issues with deformation of the lower plate due to self-weight and vibrations, leading to uneven load distribution and potential permanent deformation, which hinders smooth extension and contraction of the boom body.
Innovation Solution
A telescopic boom design featuring rollers with an outer peripheral surface curved in a convex shape to ensure that both end portions are away from the lower plate, dispersing loads and preventing point contact, thereby reducing the risk of deformation during vehicle travel or operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the lower plate is formed to be thin in thickness for lightweight of the boom body, then the weight of the boom body is reduced, but the lower plate becomes susceptible to deflection by self-weight and collision damage from the roller
Solution Approach 1:
The lower plate is designed with non-uniform thickness, being thicker at the contact portions with the roller and thinner at other areas. This local quality variation allows the lower plate to maintain overall lightweight while providing enhanced strength and rigidity specifically where the roller contacts, preventing deflection and collision damage.
2Device complexity
If the roller makes point-contact with the lower plate during vibration, then the contact area is minimized, but load overconcentration causes deformation of the lower plate
Solution Approach 1:
The lower plate incorporates locally thickened contact portions positioned exactly where the roller makes contact. This local structural enhancement transforms the contact interface from a weak point to a reinforced zone, distributing the roller's load over a larger area and preventing the overconcentration that leads to deformation.
Solution Approach 2:
The thickened contact portions act as pre-designed cushioning structures that absorb and distribute impact loads before they can cause deformation. By providing this structural cushioning in advance at the contact points, the design prevents harmful stress concentration during vibration and operation.
3Strength
If the lower plate is reinforced to prevent deformation, then the strength is improved, but the weight of the boom body increases
Solution Approach 1:
Instead of uniformly reinforcing the entire lower plate, the design applies local thickening only at the specific contact portions where the roller interacts with the plate. This selective reinforcement provides the necessary strength at critical locations while maintaining thin and lightweight construction in non-critical areas, optimizing the strength-to-weight ratio.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The convex roller design effectively disperses loads across a wider area, preventing deformation of the lower plate and allowing for smooth extension and contraction of the boom body, even under vibrational conditions.
Implementation Method 1
a roller which is provided at a tip end portion of the telescopic cylinder and is disposed to roll in the longitudinal direction
Data Source
AI summary
A telescopic boom provided in a crane includes a boom body and a telescopic cylinder for extending/contracting the boom body. A roller is provided in a tip end portion of the telescopic cylinder to be rotatable in a longitudinal direction. A peripheral surface of the roller is formed to be curved (crowning) in a convex shape outside as viewed in the longitudinal direction and make contact with a lower plate of the boom body in a state where both corner parts are away from the lower plate.