Two-Flange Pulley Joint Geometry to Prevent Ultrasonic Weld Burrs
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Solution Overview
Problem
Weld burrs are ejected during ultrasonic welding of pulley bodies and flange bodies, leading to defects and increased production costs due to the need for removal and processing.
Innovation Solution
A pulley with two flanges is designed with a male-female fitting manner, incorporating annular-shaped fitting protrusions and recesses with inclined surfaces to guide molten resin flow, preventing weld burrs by providing continuous protrusions or recessed grooves that inhibit resin movement during ultrasonic welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultrasonic welding is used to join pulley body and flange body, then joining strength is improved, but weld burrs are ejected causing defects and increased production costs
Solution Approach 1:
The patent converts the harmful effect of molten resin ejection into a beneficial feature by designing protrusions and recessed grooves that redirect the molten resin flow. The molten resin that would normally form burrs is now channeled into filling the recessed grooves, transforming the harmful ejection into a useful filling action that prevents burr formation while maintaining strong joints
Solution Approach 2:
The patent applies local quality by creating specific geometric features (protrusions and recessed grooves) at critical locations where molten resin flows during welding. These localized structural modifications are positioned precisely to intercept and redirect resin flow, preventing burr formation at the joint interface while maintaining overall joint strength
2Manufacturing precision
If weld burrs are removed and processed, then product quality is improved, but production cost increases
Solution Approach 1:
The patent applies preliminary action by incorporating protrusions and recessed grooves into the mold design before welding occurs. These features are pre-formed in the pulley body and flange body, so that during welding the molten resin is automatically directed into the recessed grooves, preventing burr formation in the first place and eliminating the need for subsequent burr removal operations
Solution Approach 2:
The patent eliminates post-welding processing by converting the harmful molten resin ejection into a beneficial filling action. The recessed grooves capture the molten resin that would otherwise form burrs, transforming a quality defect into a design feature that prevents the need for additional processing steps
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
The design effectively prevents weld burrs from forming, reducing production costs and ensuring smooth assembly by maintaining the integrity of the joint without burrs.
Implementation Method 1
ultrasonic welding of the pulley body and the flange body
Implementation Method 2
a weld burr ejected from a joining portion
Implementation Method 3
a region including an annular-shaped area between the first inclined surface and the second inclined surface includes a joint portion of a molten resin
Data Source
AI summary
A pulley body has a first flange and a fitting protrusion. The flange body has a second flange and a fitting recess fitted to the fitting protrusion. The fitting recess has an inner surface including, in a radially inward direction, a first inclined surface inclined so as to approach the first flange, as extending in the radially inward direction. The fitting protrusion has a distal end surface including, in the radially inward direction, a second inclined surface facing the first inclined surface. The flange body has an outer peripheral surface that faces an inner peripheral surface of the pulley body, and has a protrusion which continues in a circumferential direction with no end. A region including an annular-shaped area between the first and second inclined surfaces includes a joint portion of a molten resin.