Plastic Laundry Container Screw Joint for Leak-Resistant Cap Fit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing plastic suds containers for washing machines face issues with unreliable non-positive screw connections due to material shrinkage and deformation, leading to incomplete form-fitting connections and potential leaks under transverse forces.
Innovation Solution
The design features a cone form fit with a minimal screw undercut height on the dome, adjustable inserts for optimal contact, and parabolic ribbing on the screw tube for enhanced support, along with self-tapping screws and sleeve-shaped screw channels with external ribbing to ensure a secure and stable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conical seat is used for form-fitting connection in screw channels, then a positive connection is provided, but the connection becomes imprecise due to material shrinkage and deformation leading to irregular contact patterns
Solution Approach 1:
The patent changes the geometric parameters of the screw channel by introducing a dome shape with optimized curvature radius and height. This parameter optimization ensures that the dome can be properly compressed into the conical seat without excessive material deformation, maintaining precise form fit despite material shrinkage during injection molding.
Solution Approach 2:
The patent incorporates the dome shape directly into the molded container shell before assembly. This preliminary formation of the dome during the molding process ensures consistent geometry and eliminates the need for subsequent machining or adjustment, achieving precise form-fitting connection through pre-formed geometric features.
2Manufacturing precision
If the screw undercut height on the dome is increased to improve form fit, then the cone may be crushed and deformed, but this impairs centering and connection quality
Solution Approach 1:
The patent optimizes the dome geometry by carefully selecting the curvature radius and height parameters. The dome height is specifically designed to be sufficient for form fit but limited to prevent excessive compression that would crush the conical seat. This parameter balancing achieves complete form fit in axial and radial directions without deforming the cone shape.
Solution Approach 2:
The patent uses a dome shape with optimized curvature instead of a sharp or flat top on the screw channel. This curved geometry distributes compression forces more evenly during assembly, preventing localized stress concentrations that would crush the conical seat while still achieving complete form fit through controlled material flow.
3Strength
If multiple screw connections are distributed around the circumference to handle transverse forces, then the connection strength is improved, but the complexity of the connection arrangement increases
Solution Approach 1:
The patent divides the connection task into multiple screw connections distributed around the circumference of the container shell. Each screw connection handles a portion of the transverse forces, and the distributed arrangement provides balanced load distribution. This segmentation approach improves overall connection strength without requiring overly complex individual connection details.
Solution Approach 2:
The patent designs the screw connections to serve multiple functions simultaneously: providing form-fitting positive connection through the dome-cone interface, enabling non-positive connection through thread engagement, and distributing transverse forces through distributed positioning. This multi-functionality reduces the need for separate connection mechanisms, simplifying the overall arrangement.
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 configuration achieves a complete or nearly complete form fit in both axial and radial directions, preventing deformation and ensuring secure attachment under operational forces, thus preventing leaks and enhancing the durability of the washing unit.
Implementation Method 1
a self-tapping screw which can be screwed into a screw channel formed on the front wall of the container shell to produce a non-positive connection
Implementation Method 2
screw connections that produce the non-positive connection between the container shell and the tub cap
Implementation Method 3
a dome being formed on the screw channel, which engages in a conical seat molded into the tub cap to produce a form-fitting connection when screwed in
Implementation Method 4
the dome is expanded slightly with a self-tapping screw and squeezed into the cone seat
Implementation Method 5
the plastic is crushed and melted when the screw is screwed in, which leads to a deformation of the centering cone
Implementation Method 6
the plastic is crushed and melted when the screw is screwed in
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The plastic lye container (1) has a cylindrical container (2) surrounding the drum, where the cylindrical container consists of a molded container shell (3), on which a plastic lye container cover (5) is fixed on the front side (4). The height of a screw relief groove at a dome on the front side of the container shell is less than the height of a taper formed at the lye container cover.