Dumbbell Weight Assembly Collar Welding Method
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Solution Overview
Problem
Conventional dumbbells and barbells face issues with loose collars leading to weight rotation and disconnection, increasing manufacturing costs due to the need for threaded securing means and high tensile screws, and poor tolerance between the bar and weight head, resulting in wobbling and loosening.
Innovation Solution
The method involves forming a weight section around a collar, which acts as a second securing member, providing an interference fit to prevent movement, and using an end plate secured by welding or flaring to distribute force and secure the weight assembly, eliminating the need for threaded fastenings and improving fit accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded securing means (locking nuts, mounting screws) are used to secure weights to the bar, then the weights can be retained in position, but the manufacturing cost increases due to the need for high-quality threads, high tensile screws, and thread locking compounds
Solution Approach 1:
The patent extracts and eliminates the threaded securing means (locking nuts, mounting screws, thread locking compounds) from the dumbbell construction. Instead, it uses a dual-fixing mechanism consisting of an interference fit between the bar end portion and weight head, combined with a collar and welding, thereby removing the need for expensive threaded components while maintaining secure weight retention.
Solution Approach 2:
The patent replaces the threaded mechanical fastening system with a welding-based mechanical system. The collar is welded to the bar end portion, creating a permanent mechanical bond that substitutes for the removable threaded securing means, thereby eliminating the need for screws, nuts, and thread locking compounds.
2Reliability
If threaded securing means are used to retain weight heads, then weights can be secured to the bar, but additional manufacturing steps (thread formation, nut attachment, screw attachment, locking compound application) increase manufacturing time and cost
Solution Approach 1:
The patent removes the multi-step threaded securing process (thread formation, nut attachment, screw attachment, locking compound application) and replaces it with a simplified process involving interference fit assembly followed by collar welding, significantly reducing the number of manufacturing steps required to secure weights to the bar.
Solution Approach 2:
The interference fit between the bar end portion and weight head is established during the casting or machining of these components, before assembly. This preliminary preparation eliminates the need for thread formation and multiple fastening steps during final assembly, thereby reducing manufacturing time.
3Ease of manufacture
If poor tolerance exists between the bar end portion and weight head inner bore, then manufacturing is easier, but lateral movement occurs leading to wobbling and loosening of securing means
Solution Approach 1:
The patent changes the dimensional parameters of the bar end portion and weight head inner bore to create an interference fit, where the bar end portion has a slightly larger diameter than the weight head inner bore. This parameter change eliminates lateral movement and wobbling while maintaining ease of manufacture through standard machining tolerances.
Solution Approach 2:
The collar acts as an intermediary component between the bar end portion and the weight head. It is fitted over the bar end portion and welded to it, providing a stable mounting surface for the weight head while compensating for any minor tolerance variations, thereby preventing wobbling and loosening.
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
This approach reduces manufacturing time and cost, enhances the stability of the weight assembly by preventing loosening and fracture, and allows for a permanent securement of the weight assembly to the bar, ensuring user safety and improved performance.
Implementation Method 1
The collar is provided to prevent movement between the end portion and the weight assembly. An interference fit is provided between the collar and the end portion.
Implementation Method 2
The end plate is secured to the end portion by a weld.
Implementation Method 3
The outer skin is compressed until the end plate contacts the first projection. The outer skin remains compressed when the compressive force is subsequently removed. Due to its resilient properties, the compressed outer skin applies a force to the weight assembly to urge it against the locating member.
Data Source
AI summary
A method of manufacturing an exercise device, includes the steps of providing a bar having an end portion; providing a collar for receiving the end portion; forming a weight section about the collar to form a weight assembly including a weight section and a collar; mounting the weight assembly on the end portion; providing a first securing member; and securing the weight assembly to the bar using the first securing member. The weight section is formed about the collar by casting.