Automatic and Continuous Screenchanger
Over 40 years have passed since the invention of AutoScreen screenchanger. We are now glad to introduce you POWERBELT, our new model - a thoroughly renewed product, which is able to comply with the most recent requirements from the plastics industry. Thanks to the entirely new melt channels design, and to an innovative and enhanced control panel, its performance and stability are extremely powered. Today, POWERBELT is definitely suitable for processing highly contaminated materials, such as industrial post consumer ones. Screenchanger start-up has been drastically optimized. Today, POWERBELT represents the excellent solution for a wide range of products: blown and cast films, thermoformed products, foamed sections, oriented bands, yarns, wires, pipes and many other products that benefit from a continuous extrusion and extremely stable process conditions. One fact for all: an irrelevant pressure drop during screen replacement. Thanks to its compactness, POWERBELT requires reduced housing space around blow line heads and inside injection machines. POWERBELT has no motor, gears, hydraulic or pneumatic components, and no moving part except for the screen itself, thus being virtually undestroyable. With no need for manual replacement of screen and breaker, all operations and possible human mistakes - typical of manual screenchangers with sliding and rotary plate - have been definitely eliminated.
Fundamentals on Operation
Once POWERBELT has been installed, the cooling system connected to the water supply, and the resistance heaters, thermocouples and pressure transducers connected to the control panel by the pre-cabled wires supplied together with the unit, POWERBELT can be started. The filtering screen, previously rolled up, is housed into the canister. It moves through POWERBELT, advancing in the melt flow towards the exit, thus retaining the filtered contaminants contained inside the molten polymer. During the extrusion process, the screen is advanced as described below, with no mechanical backing. Screenchanging is produced by the switchover between cooling and heating of the screen and of the molten polymer.
1. Cooling – Cool water uninterruptedly circulates in the entry and exit sections. The molten polymer, if cooled, solidifies and creates a pressure-tight seal capable of standing internal pressure, thus generating a barrier between the melt flow and the air – the polymer is kept in and the air out.
2. Heating – Whenever excessive contaminant accumulation on the screen occurs, screen advance is required. To the purpose, the end part of the solidified plug is heated up and the melt seal softened, ready to be moved onwards by the melt pressure.
3. Screen Advance – The melt seal on the exit section – which contains the screen and the screen-accumulated contaminants – is pushed toward the exit section by the melt pressure. The advancing screen is slowly replaced by a new entering screen, which is obviously clean and free from contaminants.
4. Screen Advance Interruption – Whenever the molten polymer is free from contaminants, thus rendering screen advance no longer required, the heating elements on the exit side are switched off. The polymer solidifies, sealing the exit opening and interrupting screen advance.
Control System
The standard control system is fully automatic and operates screen advance depending on the material contamination level. Time, pressure, dual or manual control modes are available:
- Time control: it simply moves the screen at preset fixed intervals.
- Pressure control: it is strongly recommended in case of differently contaminated materials. A digital pressure controller maintains the set pressure difference or detects the set max. entry pressure value. Once the set threshold is reached, screen advance is operated, thus assuring stable process conditions even with different material quality and optimizing screen wear.
- Dual control: screen advance may be started both by preset time and by exceeding set pressure thresholds.
- Manual mode: continuous screen advance, uninterrupted.
Two additional heating zones are available and can be managed – normally at entry and exit flange zones.
All main operating parameters can be monitored from the control panel:
- POWERBELT upstream and downstream pressures
- Heating zone real-time temperatures and set point values
- Actual power consumption of the different heating zones
- Operating condition of the automatic screen advance process
- Timing
All system parameters are easily configurable via a touch screen type control panel.
System configuration pages are password protected.
The control system is multi-language; the required interface language is selected in the configuration page.
The control system can be integrated into the extruder one.
POWERBELT heating can be directly switched ON from the extruder control system.
POWERBELT is thus enabled to communicate the extruder that the required temperature set point has been reached.
| Processing | Continuous flow, automatic |
|---|---|
| Type of material | Steel |
| Nominal diameter breaker | From 35 to 200 mm (1-1/4" to 8") |
| Heaters | Armored |
| Material contamination | High, post industrial consumption too |
| Operating temperature | Up to 350º C (662° F) |
| Pressure | Up to 700 bar (10,000 psi) |
| Hourly capacity | Up to 2500 kg/h (5500 pounds) |
| Polymers | HDPE, LDPE, LLDPE, PP, ABS, PET, PS, Nylon, etc. |
| Products and Applications | Suitable to any kind of product and application |
POWERBELT vs AutoScreen
- Higher Speed in Screen Advance
The thoroughly redesigned inner channel and the relevant high lubricating capacity surface treatments allow an incredibly higher speed in screen changing (i.e. the time the screen takes to be advanced of a whole breaker plate diameter is definitely shortened). To make an actual example, AutoScreen took 60-90 minutes where POWERBELT takes 10-15 minutes. Obviously, no precise parameters may be provided as performance depends on several factors, such as material type, process conditions and required filtering level. We will be much pleased to offer you a trial at our lab, even with your material, to let you see the actual results obtained with the material you are interested in.
- Performance Evenness
As a wider range of operating parameters may be more precisely configured, POWERBELT is suitable for a wider range of operating conditions (material, pressure, temperature, contaminants, MFI, ...), thus making its applicability extremely enhanced. AutoScreen was extremely performing only in a limited number of applications and provided that process conditions did not significantly vary.
- Processability of Highly Contaminated Materials
Thanks to its quicker screen advance, POWERBELT may process higher contaminated materials if compared to AutoScreen, such as post industrial ones.
- Higher Filtering Level
Thanks to its capacity to make screen advance in highly contaminated conditions, POWERBELT applicable filtering levels, at the same operating conditions, are significantly enhanced if compared to AutoScreen ones.
- Modification of Filtering Screen Pre-Tensioning
With POWERBELT, pre-tensioning of the screen is automatic and does not required any operator intervention, unlike AutoScreen, whose manual pre-tensioning could cause misalignments and consequent stoppages.
- Easier Cleaning Procedure
Today, extraordinary maintenance operations, such as inner melt channel cleaning, may be carried out simply and quickly, as POWERBELT is openable in two parts. AutoScreen did not allow such operation as it consisted of a single block.
- Enhanced Operating Parameter Control
POWERBELT operating parameters are easily configurable, thus allowing a more precise control of screen advance and stop.
- Higher Wear Resistance
POWERBELT innovative surface treatment provides maximized wear resistance. AutoScreen featured no surface treatments, thus inevitably causing wear and rusting.
- Reduced Screen Wear Thanks to Enhanced Control
POWERBELT screen advance and stop is much quicker, thus maximising screen wear resistance and prolonging screen replacement intervals and considerably lowering costs.
- A Single Model for Any Pressure Level
Unlike AutoScreen, which featured 3 different modes for low, mid and high pressures, POWERBELT was designed as a single model, which perfectly suites any pressure level up to 700bar (10,000psi) max. This allows for easy management of different process conditions on the same production line.
- 3 Freely Configurable Heating Zones
POWERBELT control panel provides management of 4 heating zones. One is dedicated to exit zone heating. The remaining 3 zones may be freely configured (body, entry flange, exit flange) or switched off whenever other existing temperature control zones are employed (e.g. on the extruder control panel). AutoScreen did not allow control of any heating zone.
- Extremely Easy Wiring
POWERBELT connection to control panel is via cables featuring pre-wired connectors, which only require to be connected to plugs. AutoScreen had no pre-wired connectors.
- Easier Screenchanger Start-Up
Start-up has been sensibly simplified by screen pre-tensioning and by the independent management of the 2 cooling zones. Cleaning operations are infinitely easier as screenchanger parts can be rapidly disassembled.