Moldable Clip With Hinged Ribs For Undercut Avoidance

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Solution Overview

Problem

During injection molding of resin-made vehicle bumpers, the clip holding section often becomes an undercut, making mold opening difficult, and the process of bending ribs to pass between stopper sections is inefficient, leading to prolonged production times.

Innovation Solution

The design includes a movable section with first and second ribs that can easily bend due to formed grooves, allowing efficient passage between stopper sections, and are then fixed in a horizontal attitude by stopper engagement, improving production efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the clip holding section is molded in an upright attitude to avoid undercut, then mold opening becomes possible, but the clip holding section cannot be efficiently positioned in the horizontal attitude required for final product

Engineering Contradiction:

Improvemold openingVSAvoidproduction efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The clip holding section is designed as a movable section that can change its attitude from upright (during molding) to horizontal (in final product) by revolving about the hinge section. This dynamic repositioning allows the same structure to satisfy both molding requirements and final product requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The attitude parameter of the clip holding section is changed from upright to horizontal by controlling the revolution angle about the hinge section. The stopper sections are positioned to engage the ribs at a specific revolution angle, thereby fixing the attitude parameter at the desired horizontal position.

Inventive Principle:

Principle #35Parameter changes

2Strength

If the width of the clip holding section is set larger to ensure proper engagement, then the structural integrity is improved, but the time required to pass between stopper sections increases

Engineering Contradiction:

Improvestructural integrityVSAvoidpassage time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The clip holding section is segmented into a movable main body and protruding ribs. The ribs are designed to be flexible and capable of bending, allowing them to deform during passage between stopper sections and then engage firmly after passage. This segmentation enables both flexible passage and firm engagement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The ribs of the clip holding section are designed with flexibility, allowing them to bend during the passage process between stopper sections. This flexibility enables the ribs to deform temporarily to pass through the clearance and then engage firmly with the stopper sections after passage, reducing passage time while maintaining structural integrity.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If the ribs are made rigid to maintain structural stability, then the engagement reliability is improved, but the ability to bend and pass between stopper sections is reduced

Engineering Contradiction:

Improveengagement reliabilityVSAvoidbending ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Different parts of the clip holding section have different rigidity characteristics. The movable main body maintains high rigidity for structural stability, while the ribs are designed with appropriate flexibility to enable bending during passage. This local differentiation of quality allows the structure to satisfy both engagement reliability and bending ease requirements.

Inventive Principle:

Principle #3Local quality

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 enables quick attitude change of the movable section, reducing production time and improving efficiency in obtaining the final product with the clip holding section fixed in a horizontal position.

Implementation Method 1

the movable section is coupled to the main body section via a hinge section... the clip holding section is revolved with the hinge section as its center of revolution

Methodology Applied

Scientific EffectRotation:

Implementation Method 2

After passage, the clip holding section attempts to return to its original position (the upright attitude) by elastic action

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11161467B2Injection molded article

Publication Date: 2021.11.02 HONDA MOTOR CO LTD

AI summary

This injection molded article has a body part and a movable part. The body part has a first stopper part and a second stopper part, while the movable part has a movable body and a first rib and a second rib that are formed to protrude at both widthwise end parts of the movable body. A first groove and a second groove that extend in the depth direction perpendicular to the axial direction of a hinge part, are respectively formed between the movable body and the first rib and between the movable body and the second rib.