Sports Racquet Frame Molding with Inflatable Bladders
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Solution Overview
Problem
Conventional methods for manufacturing sports racquet frames with enlarged string port holes are costly and may weaken the frame due to post-curing operations like drilling, or are complex and difficult to implement on a large scale.
Innovation Solution
A method involving a moldable tube structure with inflatable bladders and mold members is used to form the racquet frame, where cross channels guide the shape of the string port holes during molding, eliminating the need for post-curing operations and allowing co-molding of different materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional drilling methods are used to create string port holes after molding, then enlarged string holes can be formed, but the frame structure is weakened due to fiber breaking
Solution Approach 1:
The patent applies preliminary action by forming the string port holes during the molding process itself, before the frame is fully cured and strengthened. Mold members are inserted into the mold cavity to define the string port hole shapes, and the frame material is molded around them. This eliminates the need for post-molding drilling operations that would break fibers and weaken the frame structure.
Solution Approach 2:
The patent uses mold members as intermediaries to create the string port holes. These mold members are temporarily inserted into the mold cavity during molding to define the hole shapes, then removed after curing to leave clean, strength-preserving openings. This intermediary approach avoids direct mechanical drilling that would damage the frame fibers.
2Strength
If double tube structures are used to form string port holes, then rounded edges and improved torsional stiffness are achieved, but production costs increase
Solution Approach 1:
The patent applies local quality by using a single tube structure with strategically placed mold members only at the specific locations where string port holes are needed. Instead of using expensive double tube structures throughout the entire frame, the mold members locally define the hole shapes only at critical areas, achieving rounded edges and proper geometry where required while maintaining cost-effective single-tube construction elsewhere.
3Shape
If post-curing drilling operations are performed, then string port holes can be created, but the manufacturing process becomes complex and difficult to scale
Solution Approach 1:
The patent merges the string port hole formation operation with the frame molding operation into a single integrated process. By inserting mold members into the mold cavity before closing and molding the frame, the string port holes are created simultaneously with the frame structure itself. This eliminates separate post-curing drilling operations and reduces manufacturing process complexity, making the process easier to scale for mass production.
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 method reduces production costs, maintains the structural integrity of the racquet frame, and allows for easier stringing while improving performance by creating enlarged string holes without drilling, thus enhancing the racquet's mechanical properties and comfort.
Implementation Method 1
pressurizing the first and second bladders, so that the tube structure conforms to the shape of the mold
Implementation Method 2
heating the mold, so that the tube structure cures
Data Source
AI summary
The present invention relates to a method for manufacturing at least a portion of a sports racquet frame that comprises a step a) of providing a moldable tube structure containing a first inflatable bladder and a second inflatable bladder. The first and second inflatable bladders are positioned on opposite first and second regions of the moldable tube structure. At an intermediate region, the tube structure comprises one or more cross channels, which pass through the moldable tube structure. The method according to the present invention comprises also a further step b) of inserting said tube structure inside a mold forming a mold cavity of a desired shape. Mold members are inserted into the cross channels of the tube structure, so that the outer surface of the mold member faces the inner surface of the corresponding cross channel. The mold members have position and orientation that correspond to the position and orientation, along the string bed plane, of the string port holes, which are to be formed on said frame portion. The method, according to the present invention, comprises also a step c) of pressurizing the first and second bladders, so that the tube structure conforms to the shape of the mold, and heating the mold, so that the tube structure cures. The method, according to the present invention, comprises a further step d) of removing the cured tube structure from the mold cavity and removing the mold members from the cross channels.