Jib Overhanging Storage Mechanism with Multi-Raceway Guide
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Solution Overview
Problem
Jib overhanging storage mechanisms face challenges in storing jibs due to deflection and play in large cranes, particularly with round booms, which cause positional deviations of the jib fixing pin and insertion hole, preventing successful insertion and storage.
Innovation Solution
A jib overhanging storage mechanism featuring a guide roller and guide with raceway surfaces, including a third raceway surface for correction, and a jib fixing pin with a conical end, along with insertion holes of varying dimensions to absorb positional deviations and facilitate insertion, ensuring the jib can be stored even with deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional guide mechanism is used for jib storage, then the mechanism structure is simple, but the jib fixing pin cannot be inserted into the boom side pin socket due to positional deviation caused by deflection and play
Solution Approach 1:
The guide is divided into multiple sections with different raceway surface orientations. The first raceway surface guides the guide roller during initial approach, the second raceway surface corrects positional deviation, and the third raceway surface provides final positioning. This segmentation allows each section to perform a specific function, resolving the contradiction by making the guide mechanism complex only where necessary to correct deflection and play.
Solution Approach 2:
The invention introduces a multi-dimensional guiding approach by using raceway surfaces with different orientations and positions. The guide roller moves through three-dimensional space along curved trajectories defined by the different raceway surfaces, adding spatial dimensionality to the guidance process. This allows correction of positional deviations in multiple directions simultaneously, ensuring reliable pin insertion despite deflection and play.
2Manufacturing precision
If the insertion hole dimensions are tightly fitted, then the connection precision is high, but the jib fixing pin cannot be inserted due to positional deviation
Solution Approach 1:
The insertion hole is designed with non-uniform dimensions along its length. The front end opening portion has larger dimensions to accommodate positional deviation and facilitate easy insertion, while the rear end opening portion has smaller, tightly fitted dimensions to ensure high connection precision once inserted. This local variation in quality allows the insertion hole to perform both functions: easy insertion and precise connection.
Solution Approach 2:
The guide mechanism performs preliminary positioning action before the pin reaches the insertion hole. By the time the jib fixing pin approaches the insertion hole, the guide roller has already guided it through the raceway surfaces to correct most of the positional deviation. This preliminary action reduces the tolerance requirement of the insertion hole, allowing it to maintain tight fitting dimensions while still accepting the pin easily.
Data Source
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AI summary
The overhanging storage mechanism for a jib is provided with: a guide roller (31) and a pin socket (45) that are provided to a jib (15); and a guide (32) and a jib-fixing pin (43) that are provided to a base end boom (14a). The guide (32) comprises a first raceway surface (34s) that pulls the jib (15) toward the bottom surface of the base end boom (14a) as a result of rolling of the guide roller (31), a second raceway surface (35s) on which the jib (15) moves along the base end boom (14a), and a protruding third raceway surface (36s) that protrudes from the second raceway surface (35s). The jib (15) is pulled further toward the bottom surface of the base end boom (14a) by rolling of the guide roller (31) on the third raceway surface (36s).