Continuous Plastic Welding Stationary Heat Source Rotation

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Solution Overview

Problem

Existing methods for welding plastic parts fail to achieve high cycle times and unit production rates, which are essential for manufacturing products like final packaging for food or mass-produced medical items, such as hollow needles, where secure closure welding is required.

Innovation Solution

The method involves moving plastic parts into a joined position and conveying them past a stationary heat source while rotating to ensure uniform application of welding energy around the joint region, utilizing a combination of conveying elements and a stationary heat source, such as laser or infrared heaters, to facilitate continuous welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a through-welding process with laser light source is used to weld plastic parts, then welding capability is achieved, but cycle time is high and unit production rate is low

Engineering Contradiction:

Improveunit production rateVSAvoidcycle time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

Instead of moving the heat source along the joint region as in conventional methods, the invention inverts the approach by keeping the heat source stationary and rotating the product itself. This inversion enables continuous welding without stopping the conveyance motion, thereby reducing cycle time and increasing unit production rate.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention implements continuous welding by maintaining the product in constant motion through the welding zone. The product is conveyed continuously past the stationary heat source while rotating, ensuring uninterrupted welding action and eliminating idle time between welds, thus improving productivity.

Inventive Principle:

Principle #20Continuity of useful action

2Manufacturing precision

If the laser light source is moved along the joint region to melt the plastic, then welding is achieved, but positioning and clamping times increase

Engineering Contradiction:

Improvewelding qualityVSAvoidpositioning time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The product is pre-positioned and clamped in the correct relative position before entering the welding zone. Once in position, the continuous conveyance and rotation maintain this positioning throughout the welding process, eliminating the need for repeated positioning adjustments and reducing overall positioning time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces the mechanical movement of the heat source along the joint with a rotational motion of the product itself. This substitution allows the welding to occur continuously as the product rotates past the stationary heat source, reducing the time required for positioning and clamping operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If conventional welding methods are used for plastic parts, then welding is achieved, but production speed is low

Engineering Contradiction:

Improveproduction speedVSAvoidwelding system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The conveying elements serve multiple functions: they transport the product through the welding zone and simultaneously provide the rotational motion needed for uniform heat distribution. This multi-functionality increases production speed without requiring separate dedicated rotational drive mechanisms, thus avoiding increased device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach enables high cycle times and unit production rates by ensuring consistent energy application to the entire joint region, reducing clamping and positioning times, and allowing for flexible handling of products with curved surfaces without additional rotational drives.

Implementation Method 1

conveying the product past a stationary heat source... apply the welding energy to the joint region

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

Laser light sources are advantageously employed as the heat sources

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 3

the product being rotated when being conveyed past the stationary heat source so as to apply the welding energy to the joint region

Methodology Applied

Scientific EffectRotational motion:

Implementation Method 4

the product being conveyed past a stationary heat source

Methodology Applied

Scientific EffectMechanical conveyance:

Data Source

PatentUS9221215B2Method and device for the continuous welding of plastic components of a product

Publication Date: 2015.12.29 BIELOMATIK LEUZE GMBH CO KG

AI summary

For continuous welding of plastic components (1, 2) of a product along a join region extending over the circumference, the plastic components (1, 2) to be welded are first positioned in the join position thereof and fixed therein. Then, for the welding process, the product is transported past a fixed heat source (5) and is subjected to its own rotary movement in the region of the fixed heat source (5), in addition to the transport movement, in order to insert the welding energy into the join region.