Composite Window Frame With Sliding Thermal Expansion Compensation

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Solution Overview

Problem

Existing composite frames for windows and doors face challenges in efficiently connecting metal and plastic frames due to different thermal expansions and manufacturing tolerances, leading to inefficiencies on production lines.

Innovation Solution

A composite frame design where metal front frames are connected in the corner area using commercially available connectors and plastic base frames are welded in the mitre area, with a locking function allowing relative displacement and compensation for thermal expansion and tolerances, ensuring a stable connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If individual facing profiles are placed on the legs of a base frame and connected using adhesives, screws, or fasteners, then the connection can be made, but the process becomes time-consuming and cannot be efficiently processed on conventional production lines

Engineering Contradiction:
Improveconnection stabilityVSAvoidassembly speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The invention merges the base frame and facing frame into a single integrated unit by injecting molten plastic into the corner connectors during base frame production. This combining of materials and processes eliminates subsequent assembly steps, allowing the integrated unit to be produced efficiently on conventional injection molding production lines while ensuring reliable connections.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The corner connectors are pre-formed and integrated into the base frame during the injection molding process before the facing frame is attached. This preliminary preparation of connection elements enables rapid subsequent assembly and eliminates time-consuming fastening operations that would otherwise be required.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If snap-in or clip-on connections are used to connect front frames to the base frame, then assembly can be simplified, but the different thermal expansion of aluminum and plastic and manufacturing tolerances create problems

Engineering Contradiction:
Improveassembly simplicityVSAvoidconnection stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the material parameter of the corner connectors by using plastic material that is compatible with both the aluminum facing frame and the plastic base frame. This parameter change allows the connector to accommodate thermal expansion differences and manufacturing tolerances while maintaining a stable, integrated connection that behaves as a unified structure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses composite construction by integrating the plastic base frame, plastic corner connectors, and aluminum facing frame into a single hybrid structure. The plastic corner connectors act as intermediate material that bridges the two different materials, allowing them to work together as a unified composite frame system that accommodates their different properties.

Inventive Principle:
Principle #40Composite materials

3Strength

If double locking bars are used to connect front frames to the plastic base frame, then connection strength can be improved, but the different thermal expansions and tolerance compensation still pose problems

Engineering Contradiction:
Improveconnection strengthVSAvoidthermal expansion compatibility
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention extracts the locking function from separate mechanical locking bars and integrates it directly into the molded plastic corner connectors. This extraction and integration of the locking mechanism into the base structure eliminates the need for separate thermal expansion compensation components while maintaining strong connections that accommodate material differences.

Inventive Principle:
Principle #2Taking out (Extraction)

4Manufacturing precision

If plastic profiles are mitered and welded together at the mitered joint, then the base frame can be formed, but the production process becomes complex and time-consuming on timed production lines

Engineering Contradiction:
Improveframe assembly precisionVSAvoidproduction line speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The invention replaces the mechanical mitering and welding process with an injection molding process. The corner connectors are formed by injecting molten plastic into molds that create the mitered joints, eliminating the need for separate mitering and welding operations. This substitution of manufacturing methods enables efficient production on conventional injection molding lines while maintaining precise frame assembly.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Enables efficient assembly on timed production lines by accommodating thermal expansion and tolerances, providing a stable and rational connection between metal and plastic frames.

Implementation Method 1

a base frame made of plastic profiles welded to one another in the mitre area

Methodology Applied
Scientific EffectWelding: Welding

Implementation Method 2

the necessary sliding capability of the front frame relative to the base frame is ensured before the panel or glazing is inserted and secured... different thermal expansions of aluminum and plastic, as well as the compensation of tolerances

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3783182B1Composite frame for a window or door
Publication Date: 2025.08.20 PROFINE GMBH
  • EP3783182B1 patent drawingFigure 1~2
  • EP3783182B1 patent drawingFigure 3~4
  • EP3783182B1 patent drawingFigure 5

AI summary

A composite frame (2) for a window (1) or door is proposed, comprising, for efficient manufacturing, an outer cover frame (3) made of metal profiles (4) connected at the corners and a base frame (13) made of plastic profiles (15) welded together at the miter joints. The composite frame (2) has a rebate area (18) for receiving a glazing unit (23), in particular multiple glazing (25), as well as a plurality of glazing blocks and/or glazing blocks (26) for fixing the end face (33) of the glazing unit (23) in the rebate area (18) of the composite frame (2). The cover frame (3) and the base frame (13) each have means that together form a locking mechanism, so that the cover frame (3) and the base frame (13) can be connected to each other by means of this locking mechanism during assembly.The folding area (18) is formed in part by the end frame (3) and in part by the base frame (13), the locking function between the end frame (3) and the base frame (13) being designed such that, after the end frame (3) is connected to the base frame (13) and before the insert (23), the end frame (3) is slidably arranged relative to the base frame (13) in a plane parallel to the insert plane (24). By inserting and fixing the insert (23) into the folding area (18) formed jointly by the end frame (3) and the base frame (13), the end frame (3) is centered relative to the base frame (13) and at least largely fixed.