Composite Flexplate Friction Welding for Strong Lightweight Joints
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Solution Overview
Problem
Conventional flexplates in automatic transmissions, composed of steel, face limitations in weight reduction and balancing due to their material properties, and the welding processes used can lead to brittle joints that are prone to fracturing under operational stress.
Innovation Solution
A composite metal flexplate is developed using an aluminum center plate and a steel ring gear affixed with a solid-state joint, where friction welding generates frictional heat to forge the components together, minimizing brittle Fe—Al intermetallic compounds and enhancing joint strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel is used for the flexplate, then strength and durability are improved, but weight is increased and weight reduction is limited
Solution Approach 1:
The patent applies composite materials by joining an aluminum center plate with a steel ring gear through friction welding. The aluminum center plate provides weight reduction while the steel ring gear provides strength for gear engagement. This composite structure resolves the contradiction by combining materials with complementary properties - aluminum for lightweight and steel for strength - creating a flexplate that achieves both weight reduction and sufficient strength.
2Ease of manufacture
If MIG welding or laser welding is used to join steel components, then manufacturing ease is improved, but joint brittleness increases and reliability deteriorates
Solution Approach 1:
The patent replaces conventional welding processes (MIG or laser welding) with friction welding. Friction welding is a solid-state joining process that uses frictional heat and pressure to forge materials together without melting them. This substitution eliminates the formation of brittle weld joints characteristic of fusion welding processes, thereby improving joint reliability and resistance to fracturing while maintaining manufacturing feasibility.
Solution Approach 2:
The patent changes the fundamental parameters of the joining process by transitioning from high-temperature fusion welding to solid-state friction welding. This parameter change involves controlling frictional heat generation, contact pressure, and rotation speed to create a strong metallurgical bond without melting the materials. The parameter changes enable joint formation that avoids brittle intermetallic compound formation, resolving the reliability issue.
3Reliability
If solid-state joint with friction welding is used, then joint strength and reliability are improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the flexplate into two separate components - an aluminum center plate and a steel ring gear - that are joined through friction welding. This segmentation allows each component to be manufactured independently using optimal processes for its material, and then joined through a controlled friction welding process. The segmentation strategy manages manufacturing complexity by breaking down the complex task of creating a strong dissimilar metal joint into manageable steps: separate manufacturing followed by controlled joining.
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 composite flexplate achieves a strong and durable joint that resists fracturing, allowing for effective torque transfer while accommodating weight reduction and balancing requirements, thus improving the operational reliability of automatic transmissions.
Implementation Method 1
one of the aluminum center plate or the steel ring gear is rotated, while the other of the aluminum center plate or the steel ring gear remains stationary, so as to generate frictional heat between the contacting surfaces
Implementation Method 2
a force is applied to the contacting surfaces of the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate to plastically deform the softened regions and to forge together the contacting surfaces
Data Source
AI summary
A composite metal flexplate is disclosed that includes an aluminum center plate and a steel ring gear joined to the aluminum center plate by a solid-state joint. The solid-state joint that joins together the aluminum center plate and the steel ring gear may be formed by friction welding. During the friction welding process, a surface of an annular body of the steel ring gear is preheated, followed by bringing the preheated surface of the annular body into contact with a surface of a periphery of a circular body of the aluminum center plate. The two contacting surfaces are then caused to experience relative rotational contacting movement, which generates frictional heat therebetween and softens adjacent regions of the steel ring gear and the aluminum center plate. Once this occurs, an applied force is administered to compress and forge the contacting surfaces together, thereby establishing the solid-state joint.