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Extrusion
- Pin-Type extruders
- Transfermix extruders (MCTD)
- Extruder gear pump systems
- Multiplex extrusion systems
- Extrusion heads
- Planetruder®
Pin-Type extruders
VMI's Pin Barrel extruders are designed to generate additional shear flow in the extruder screw channel to achieve a homogeneous temperature heat-up of the rubber and plasticisation. Due to the pins, the rubber flow is divided when passing a pin and then reunited. If high energy is needed for the extruded compound, the number if pins can be successfully increased to 36 therefore ensuring high flexibility for optimisation of the cold feed extrusion process for each compound.
The picture shows a PIN70 x 14D extruder equipped with rapid die change extrusion head for apex extrusion.
Transfermix extruders (MCTD)
Our Multicut Transfermix (MCT) extruder introduces a new concept of mixing through flow division and the rearrangement of flow elements. The heart of the system is a concentric double screw which, by reducing and increasing flight depths respectively in screw and barrel, the compound is mechanically sheared and longitudinally mixed to produce a homogeneous end product.
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The picture shows a MCTD200 x 13D extruder equipped with an adjustable wide extrusion head for tread extrusion.
Extruder gearpump systems
For applications in the tire industry
For tire applications, VMI combines the highly effective plasticising properties of pin or MCTD screw and barrel configuration with the volumetric feeding properties of a gear pump to eliminate many of the disadvantages of single screw extruders. The Shark® configuration's excellent plasticising properties in the extruder are used to effectively masticate the compound and feed the gear pump. At the same time the pump generates the high die pressures without generating excessive temperatures.
The picture shows a Shark® 70 with cross head for breaker production in the VMI Baldwin line.
By using the gear pump for pressure build-up, there is less pressure on the extruder resulting in an increase in throughput for comparative extruder sizes. The extruder is used only to achieve effective mastication and ensure sufficient feed to the gear pump therefore the gear pump feed and throughput of the entire system increases as less work energy is wasted on pressure build-up.
The picture shows a Shark® 90 with cross head for breaker production in the VMI Baldwin line.
Multiplex extrusion systems
VMI-AZ offers a wide range of duplex triplex and quadruplex extruders.
Duplex system
The picture shows the MCTD150 underpack duplex extruder with an adjustable duplex head.
Triplex system
The picture shows the mini triplex system for laboratories and bicycle tire production.
The drawing shows the Quadruplex system.
Extrusion heads
Primarily for the tire industry, VMI-AZ provides an extensive range of cross heads, wide extrusion heads and multiplex heads to accommodate its extruders or other models. Rapid die change is also possible (Rapid die change extrusion head).
VMI-AZ also offers a rapid die change extrusion head that is particularly suitable for tire profile production. Pre-heating of the new die cassette is accomplished by placing it in the pre-heating position of the extruder head whilst it is still in operation. This unique AZ technology significantly reduces die change time to just a few seconds.
Above pictures showing the rapid die-change extrusion head in operation.
Cross heads for wire and fabric coating
Our cross heads are designed for the production of breaker or body ply in tire reinforcement. The main task is for the head to keep the reinforcement material in place through specially designed guides and cover the material with rubber. In most applications the head is implemented in combination with a gear pump to ensure constant flow and pressure in order to maintain sufficient contact between the reinforcement material and the rubber. These cross heads also offer the possibility to control the pressure through a tailor-made die design for every application.
The picture shows a cross head for tire breaker production in open position.
Wide extrusion heads
VMI-AZ's wide extrusion head for tire tread production and rubber sheets are specifically designed for optimum efficiency at relatively high throughputs and controlled temperatures which is achieved using very short screw-die distances, carefully designed temperature control zones and novel compound flow channel construction. The head incorporates a simple die change system and is available from 300mm (12 inches) through to 800mm (32 inches).
Above pictures show a fully automatic adjustable wide extrusion head with an open / closed die holder.
Multiplex Heads (MFK Sandwich System)
VMI-AZ's multiplex extrusion heads are base on a traditional modular design which allows vertical retraction of the upper half of the extrusion head to enable the swift exchange of flow channels. All systems are hydraulically operated and controlled by a central hydraulic power pack and the upper part of the head is opened by vertical hydraulic cylinders to enable cleaning and changing the flow channels.
The lower flow channels are either integrated or placed into the lower part of the head body (single head). If placed in, then the head body is pressed down from the upper part and moved upwards by hydraulic cylinders for cleaning and changing.
The die package is bolted together and used as a single set plus preheating of the die package is possible for quick exchange. The entire package is pressed backwards against the flow channel by the die locking system then pressed down by clamping wedges located with the electrical die heating rods.
Above pictures show a front view of the VMI-AZ multiplex extrusion head in closed / open position.
Planetruder®
- S Single drive system
- M Single drive system
- L double drive system
- XL double drive system
The Planetruder® is the perfect combination of a drag flow conveyor and volumetric operating pump for two reasons. First, it enables efficient compound plasticisation by the extruder and also efficient pressure build up by the planetary gear pump ensuring the system offers all process advantages such as high pressure build up, improved temperature output behaviour and extremely precise output opposed to standard extruder gear pump systems.
The Planetruder's unique design features a very compact layout similar to standard extruders and there is also the option of supplying either a single or double drive system. The models for a single drive system is Planetruder® S and Planetruder® M whilst the double drive system is Planetruder® L and
Planetruder® XL.
The picture shows a Planetruder® M process section with pin-type screw.
The picture shows a Planetruder® XL process section.
- Rapid die change extrusion head
- Cross heads for wire and fabric coating
- Wide extrusion heads
- Multiplex heads (MFK Sandwich System)
For more information please see our brochures or contact us sales [at] vmi-group [dot] com.