Hollow Twin-Wheel Caster with Internal Support Member
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Solution Overview
Problem
Conventional twin-wheel luggage casters have weak structural strength due to their hollow shafts, which deform under load, disrupting the rolling motion of the ball bearings and reducing their loading capability.
Innovation Solution
A hollow twin-wheel caster structure with a large-diameter hollow shaft unit and a support member, such as a circular, oval, or cylindrical ball, is integrated to prevent deformation and maintain smooth rolling, enhancing structural strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the diameter of the hollow shaft is increased to support more balls in the ball bearings, then the loading capability is improved, but the structural strength is weakened causing deformation under load
Solution Approach 1:
The hollow shaft is constructed as a composite structure combining a plastic hollow shaft body with a metal support member (circular, oval, or cylindrical) inserted within the hollow portion. This composite design allows the plastic material to provide the large diameter needed for loading capability while the metal support member reinforces the structure to prevent deformation under load.
Solution Approach 2:
The support member is strategically positioned within the hollow portion of the shaft to provide localized reinforcement exactly where needed to prevent deformation. This allows the shaft to maintain its large diameter for loading capability while adding strength only in the critical areas where deformation would occur.
2Force
If the hollow shaft deforms under overload, then the weight bearing capacity is compromised, but the ball bearing rolling motion is disrupted
Solution Approach 1:
The metal support member is pre-installed within the hollow shaft to prevent deformation before it occurs. This proactive reinforcement ensures that when overload is applied, the shaft maintains its roundness and the ball bearings can continue to roll smoothly without disruption.
3Ease of manufacture
If a hollow shaft is used to reduce weight and manufacturing cost, then the ease of manufacture is improved, but the structural strength is reduced
Solution Approach 1:
The hollow shaft combines plastic material (easy to manufacture via injection molding) with a metal support member (provides structural strength). This composite approach maintains the manufacturing advantages of plastic while adding the strength properties of metal to prevent deformation.
Data Source
AI summary
A hollow twin-wheel caster structure of a luggage includes a wheel seat for coupling to the bottom of the luggage, the wheel seat having a horizontal inner annular hole; a hollow shaft unit inserted in the inner annular hole, two ends of the hollow shaft unit extending out of two sides of the inner annular hole to form a pair of coupling portions, the center of the hollow shaft unit being formed with a hollow portion communicating with the two ends of the hollow shaft unit; two plastic wheels fitted on the coupling portions; at least one bearing fitted on the hollow shaft unit; and a support member plugged into the hollow portion of the hollow shaft unit, the support member leaning against an inner wall of the hollow portion to prevent the hollow shaft unit from being compressed and deformed.