Removable Assembly Device for Tower Crane Mast Elements
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Solution Overview
Problem
Existing jointing devices for tower crane mast elements require multiple connecting pins or bolts, leading to mechanical components projecting externally, hindering sliding and increasing assembly and disassembly times.
Innovation Solution
A removable assembly device using a single screw clamping mechanism inside the corner chords, with conical or pyramidal half-splints and a connecting screw that allows for smooth sliding and rapid assembly/disassembly, while transmitting shear forces and torsion torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple connecting pins or bolts are used to join mast elements, then the connection strength and reliability are improved, but the mechanical components project externally and hinder the sliding of mast elements
Solution Approach 1:
The connecting screw is nested within the hollow interior of the mast element chord, with its head receiving part housed inside the chord cross-section. This nesting eliminates external projections while maintaining connection functionality, allowing mast elements to slide smoothly during telescoping operations.
Solution Approach 2:
The connection mechanism is extracted from the external surface and relocated to the internal space of the mast element. By removing the connecting screw and its head receiving part from external view, the harmful external projections are eliminated while the connection function is preserved through internal positioning.
2Strength
If multiple connecting pins or bolts are used to ensure proper force transmission, then the structural integrity is improved, but the assembly and disassembly time increases
Solution Approach 1:
Multiple connection functions are merged into a single connecting screw mechanism. The screw simultaneously provides force transmission, structural integrity, and alignment functions that would otherwise require multiple separate components, thereby reducing assembly and disassembly operations.
Solution Approach 2:
The connecting screw serves multiple functions: it transmits tensile and compressive forces, provides structural reinforcement, enables alignment through its head receiving part, and facilitates rapid connection and disconnection. This multi-functionality replaces what would traditionally require multiple specialized components.
3Productivity
If a single screw clamping mechanism is used inside the corner chords, then the assembly time is reduced and sliding is facilitated, but the ability to transmit forces must be maintained
Solution Approach 1:
The force transmission mechanism is moved from an external two-dimensional surface connection to an internal three-dimensional space utilization. The connecting screw utilizes the hollow interior volume of the chord, allowing for larger diameter screws and more effective force distribution across the mast element connection.
Solution Approach 2:
The connection system employs a composite approach combining the connecting screw, the head receiving part integrated into the chord structure, and the conical bearing surfaces. This composite mechanism distributes forces across multiple contact points and material interfaces, maintaining high force transmission capability while using a single clamping element.
Data Source
Figure 1~6
Figure 3~4
AI summary
The device has a connecting screw (7) and a nut (8) arranged along vertical axes (10, 19) parallel to a longitudinal direction of half-fishplates (5, 6) of angle flanges (2), and connecting the half-fishplates. One of the half-fishplates has a recess (12), which provides access to the nut and the screw for handling the nut and the screw. The half-fishplates are fixed to corresponding ends of the flanges and have male and female support conical surfaces, whose apexes are located on the axes. The screw has a cylindrical head (23) available for its handling using a ratchet handle (29).