Plastics Band Projections via Cooled Revolving Elements
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Solution Overview
Problem
Current methods for producing plastics bands with projections are limited to soft and bendable thermoplastics and lack efficiency in producing bands with precise projections on harder plastics, such as polycarbonate or polystyrene, which are necessary for secure applications like passports, where precise alignment and anti-counterfeiting features are required.
Innovation Solution
A continuous extrusion process using cooled revolving elements with recesses to form precise projections on one or both sides of the band, ensuring the top side remains flat and even, and allowing for precise control over projection depth and ejection to achieve tolerances below 0.01 mm, enabling the use of harder plastics like polycarbonate or polystyrene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous extrusion process with cooled rollers is used to form projections, then the production efficiency is improved, but the method is limited to soft and bendable thermoplastics only
Solution Approach 1:
The invention changes the physical parameters of the plastic material by controlling temperature and pressure conditions during the forming process. The plastic is heated to become soft and formable, then cooled to harden and retain the projection shape. This allows harder plastics like polycarbonate and polystyrene to be processed continuously while maintaining projection integrity.
Solution Approach 2:
The invention introduces dynamic control of the forming process through adjustable pressure rollers and controlled cooling zones. The pressure applied by the rollers and the cooling rate are dynamically adjusted based on the specific plastic material being processed, enabling the same continuous process to handle various material hardness levels effectively.
2Device complexity
If conventional rolling methods are used to form projections, then the process is simple, but the projection precision and alignment accuracy deteriorate
Solution Approach 1:
The invention replaces simple mechanical rolling with a more sophisticated system combining controlled pressure application, temperature management, and precision-engineered roller surfaces. The rollers incorporate specific geometric profiles and pressure distribution mechanisms that ensure accurate projection formation and alignment, achieving tolerances below 0.01 mm while maintaining continuous production.
3Ease of manufacture
If softer plastics are used for projection formation, then the forming process is easier, but the mechanical strength and security features of the band deteriorate
Solution Approach 1:
The invention applies preliminary heating to the plastic material before it enters the forming zone, temporarily reducing its strength to make it formable. After the projections are formed through the pressure rollers, the material is rapidly cooled to restore its full mechanical strength. This preliminary softening followed by rapid hardening allows easy projection formation on high-strength materials.
Solution Approach 2:
The invention utilizes phase transitions of the plastic material between soft and hard states through controlled temperature changes. The plastic transitions from a hard, strong state to a soft, formable state during processing, then transitions back to a hard, strong state after forming. This phase transition approach enables both easy forming and high final strength.
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 the production of plastics bands with precise projections on one or both sides, ensuring a flat and even top side, suitable for secure applications like passports, and allowing for easy mechanical joining with other materials, enhancing security features and production efficiency.
Implementation Method 1
Following the extrusion, the band is led between a pair of interacting cooled rollers
Implementation Method 2
wherein a free space above punches in the recesses in the revolving element gradually increases from zero, with the onward rotation thereof from a starting point of a compression zone between the revolving elements to an end point just past the press nip of the through-running extruded band by movement of the punches in the recesses
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The method and device comprise measures and means for extruding a plastics band (1) and for continuously applying a precise relief of projections (11, 13, 16, 42) to at least one flat side, optionally both sides (24, 34). The plastic band (38) is fed through between a pair of cooled revolving elements (3, 4) having in their surface (29, 30) suitable recesses (12) of variable depth and having control means (8) for pressing punches (5) for controlling these depth variations. Markings (15, 25, 26) and identification means (7) can also be provided in the band (1). A plastics band with such projections and/or markings and/or identification means is also provided.