Coextrusion Machine Parallel Flow Ducts Roller Stress Relaxation
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Solution Overview
Problem
Coextrusion machines for elastomeric compounds often induce high stresses in the materials due to convergent extrusion head arrangements, leading to deformation and residual stresses in the coextruded profiled element strips, which are not adequately addressed by existing solutions.
Innovation Solution
A coextrusion machine design featuring mutually parallel flow ducts perpendicular to the circumferential direction of a rotating roller die, where the coextruded profiled element strip is joined to the roller surface for an equivalent length of at least 700 mm to relax stresses, ensuring a precise geometry and constant thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If convergent extrusion head arrangement is used, then coextrusion of multiple elastomeric compounds is achieved, but high stresses and deformation occur in the coextruded profiled element strip
Solution Approach 1:
The extrusion head is segmented into multiple independent extrusion zones, each handling a specific elastomeric compound. The flow ducts are arranged in parallel rather than convergent, allowing each compound to be extruded independently without interfering with others, thus maintaining geometry precision while achieving coextrusion capability
Solution Approach 2:
A cooling roller is introduced as an intermediary element between the extrusion head and the final product. This roller provides a cooling surface that allows the coextruded strip to adhere and cool progressively, reducing internal stresses and preventing deformation while maintaining the complex profile geometry
2Adaptability or versatility
If convergent flow ducts are used in extrusion head, then multiple compounds are combined, but residual stresses and swelling occur after extrusion
Solution Approach 1:
The cooling roller applies preliminary cooling action to the coextruded strip immediately after extrusion. By progressively cooling the strip as it adheres to the roller surface, internal stresses are relieved before the product completes its formation, preventing subsequent swelling and dimensional instability
Solution Approach 2:
The solution moves from a purely linear extrusion path to a curved path along the cooling roller. This dimensional change allows the strip to follow the roller's circumference, providing gradual cooling and stress relief in addition to the primary extrusion direction, thereby improving dimensional stability
3Manufacturing precision
If parallel flow ducts are used, then stress concentration is reduced, but complex die design is required
Solution Approach 1:
The cooling roller serves multiple functions simultaneously: it acts as a shaping die for the complex profile, a cooling surface for stress relief, and a support element for the coextruded strip. This multi-functionality reduces the need for separate complex die components while maintaining good stress distribution
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 design effectively reduces residual stresses and maintains the precise geometry of the coextruded profiled element strips, achieving better cohesion and reducing deformation, as demonstrated in tire tread and sidewall manufacturing applications.
Implementation Method 1
the profiled element strip is joined to the roller along an equivalent length of at least 700 mm... by reducing the internal stresses which are partially relaxed while the complex product remains attached to the roller
Implementation Method 2
a die which is adjacent to a roller and is designed to cooperate with the latter to shape the profiled element strip
Implementation Method 3
Each extruder is formed of a cylindrical body or barrel which is stationary, and inside which there is a screw that is coaxial with the longitudinal axis of the barrel and driven in rotation about this axis. Its purpose is to homogenize a rubber mix introduced into it in the form of a strip
Data Source
AI summary
The machine includes an extrusion head having flow ducts, the inlet orifices of which are connected to the outlets of at least two extruders for supplying extruded strips made of elastomeric compounds. The outlet orifices lead into a die which is adjacent to a roller and is designed to cooperate with the latter to shape the profiled element strip. The roller has a central axis surrounded by an external surface intended to receive the profiled element strip and a means for driving the roller in rotation about its central axis. The flow ducts are mutually parallel and are perpendicular to the circumferential direction of the roller, and the profiled element strip is joined to the receiving surface of the roller along an equivalent length of at least 700 mm.