Crosshead Die Trapezoidal Flow Channel for Uniform Elastomer Coating
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Solution Overview
Problem
The existing crosshead dies for extruding tire plies result in non-uniform flow of molten elastomer due to a 90-degree bend, leading to a less-than-optimum cross section and uneven coating thickness, as the elastomer flows more rapidly on the inside of the bend than the outside, causing the flow to be centered closer to the inside rather than aligning with the center of the channel.
Innovation Solution
A crosshead die with a trapezoidal-shaped flow channel, where the first side wall is shorter and the second side wall is longer, compensating for slower material velocity by being higher, ensuring the flow aligns with the center of the channel, thus achieving a uniform melt and coating thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rectangular cross section flow channel with a 90-degree bend is used, then the reinforcement cords can pass through in a straight, aligned manner, but the elastomer flow rate becomes non-uniform with faster flow on the inside of the bend
Solution Approach 1:
The patent applies asymmetry by changing the flow channel cross-section from a symmetric rectangular shape to an asymmetric trapezoidal shape. The first side wall is positioned closer to the centerline than the second side wall, creating an asymmetric configuration that compensates for the non-uniform flow caused by the 90-degree bend. This asymmetric design balances the flow rates on the inner and outer sides of the bend, achieving uniform elastomer flow while maintaining straight cord passage.
2Shape
If the flow channel has a rectangular cross section, then it approximates the shape of the profile die opening, but the actual flow centers closer to the inside of the bend rather than aligning with the channel center
Solution Approach 1:
The patent applies local quality by modifying specific regions of the flow channel cross-section while maintaining the overall rectangular approximation. The first side wall is positioned closer to the centerline than the second side wall, creating local asymmetry in the cross-sectional geometry. This localized modification adjusts the flow distribution to center the actual elastomer flow at the channel centerline, while the overall shape still approximates the profile die opening.
3Adaptability or versatility
If a 90-degree bend is used in the flow channel, then the channel can accommodate the extruder configuration, but the elastomer on the inside of the bend flows more rapidly than on the outside
Solution Approach 1:
The patent applies asymmetry by configuring the flow channel with a trapezoidal cross-section where the first side wall is closer to the centerline than the second side wall. This asymmetric geometry compensates for the flow rate differential caused by the 90-degree bend, balancing the velocities on the inner and outer sides of the bend while maintaining compatibility with the extruder configuration.
Data Source
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AI summary
A crosshead die for use with an extruder is disclosed. The crosshead die (100) comprises a body (101), an inlet formed in the body (101), the inlet being configured for being in fluid communication with an extruder, an outlet formed in the body, and a flow channel formed in the body (101). The flow channel extends between the inlet and the outlet and is bounded by an upper wall (140), a lower wall (142), a first side wall (144), and a second side wall (146). The flow channel is formed with a cross section that has or includes a trapezoidal shape.