Multilayer Polymer Belt Construction With Low-Stress Butt Seam Positioning
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Solution Overview
Problem
Existing multilayer polymer bodies, such as drive belts and timing belts, face durability issues due to mechanical stress at the butt seam, which tends to crack under dynamic loads, particularly in areas like the back of the belt opposite the tooth side.
Innovation Solution
A method and device for positioning the butt seam of a fabric on a polymeric base body in a predetermined and reproducible manner, using a cylindrically shaped tool with a cutting unit and centering wedge to create a defined joint, positioning the seam in an area of low mechanical stress, such as above the center of a belt tooth, thereby reducing bending stress and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fabric layer is applied around the rotating tool to protect the polymer base body, then the polymer body is protected against abrasive wear and media influence, but the butt seam area becomes a mechanical weak point prone to tearing under dynamic loads
Solution Approach 1:
The invention applies different functional requirements to different locations of the fabric layer. The butt seam joint is positioned specifically in the area above the center of a belt tooth, where the local mechanical stress characteristics differ from other areas. This location experiences lower bending stresses during operation, making it suitable for joints while maintaining protective function elsewhere.
Solution Approach 2:
The cutting unit with centering wedge is designed to pre-position the butt seam joint at the optimal location (above the center of a belt tooth) before the fabric layer is fully applied and the belt is put into service. This preliminary positioning ensures that the joint is always formed in the low-stress area, preventing premature cracks before they can occur during operation.
2Strength
If the butt seam is positioned in areas subject to high mechanical stress, then the fabric provides continuous protection, but premature cracks occur in the butt seam area under dynamic loads
Solution Approach 1:
The invention exploits the local variation in mechanical stress distribution around the belt cross-section. By positioning the butt seam specifically above the center of a belt tooth, the joint is placed in a location with favorable stress characteristics (lower bending stresses) while the rest of the fabric layer continues to provide continuous protective coverage throughout the belt circumference.
Solution Approach 2:
The invention changes the positional parameter of the butt seam joint from arbitrary or conventional locations to a specifically defined location (above the center of a belt tooth). This parameter change optimizes the stress state at the joint, reducing bending stresses and extending the service life of the polymer body while maintaining the protective function of the fabric layer.
3Stability of the object's composition
If a closed butt joint is used with overlapping fabric ends, then the fabric layer provides continuous coverage, but the overlapping area creates additional stress concentration points
Solution Approach 1:
The invention extracts the joint formation process from the continuous fabric application and treats it as a separate, controlled operation. The cutting unit with movable knife severs the fabric layer at a precisely defined position, creating an open joint that is then positioned in the optimal location. This separates the protective coverage function from the joint formation complexity.
Solution Approach 2:
The centering wedge acts as an intermediary element between the cutting unit and the rotating tool. It ensures precise positioning of the cutting unit relative to the tool, enabling accurate placement of the butt seam joint above the center of a belt tooth. This intermediary mechanism simplifies the overall process by providing a reliable, repeatable positioning method.
Data Source
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Figure 3~4
AI summary
The invention relates to a method for the layer-by-layer construction of a multilayer or multi-layered polymer body, comprising a reinforcing element, a polymeric base material, and at least one sheet structure, wherein the components are applied layer by layer to a cylindrically shaped tool (10), wherein a cutting unit (12) with a cutting edge (28) and with a knife (30) movable linearly along the cutting edge (28) extends in the region of an outer partial circumference of the tool (10) across the width of the tool (10) in the axial direction, wherein the method comprises at least the following steps: - rotating the cylindrically shaped tool (10) circumferentially (U) about a concentric axis, - placing the reinforcing element around the tool (10), - applying the polymeric base material around the rotating tool (10) to form an abutment, - applying the sheet structure around the rotating tool (10),- The knife (30) moves linearly along the cutting edge (28) so that the surface structure guided over the cutting edge (28) is cut through, forming a butt joint (14). During the movement of the knife (30), the cutting unit (12) engages with a centering wedge (16) in a form-fitting manner with at least one tooth recess (22) of a radially internal toothing (20) of the tool (10), so that the cutting unit (12) is positioned relative to the tool (10).