Screw extrusion machine

BACKGROUND OF THE INVENTION The present invention relates to an extruder screw for the processing and manufacture of rubber and thermoplastics, consisting of a body which is formed by a housing having an inlet opening at its inlet end and an outlet opening at the outlet end. The housing is rotatably mounted with an external thread worm to which the drive unit is connected.

BACKGROUND OF THE INVENTION

It has long been known in the field of extruder screw technology that the extruder screw can be formed in such a way that in the mixing zones the metal pins penetrate the envelope into the processing area of ​​the molded material. For this reason, the screw of the extruder screw is interrupted at the points where the metal pins penetrate inwards. Such known screw extruders are described, for example, in DE 22 35 784 and DE 30 03 615. These screw extruders are characterized by good mixing and homogenizing action on the material to be processed and, moreover, at the same screw speed, increased throughput of the material to be extruded by the screw extruder per unit of time. These advantages have led to the fact that cylindrical screw extruders with metal pins have become the most frequently used mixing and homogenizing screw extruders in the last 15 years with continuous improvement.

DE 11 42 839 describes a screw press with a mixing zone, which became known as transfermix. In this mixing zone, the worm and the inner wall of the sleeve are provided with a certain length of grooves and projections, while in the longitudinal direction of the sleeve the depth of engagement of the worm decreases to zero and increases in the same way as the grooves of the sleeve increase or decrease.

With such a screw and sleeve design, with the rotating screw in the mixing zone, it is possible to transport the molded mass from the screw grooves to the sleeve grooves, thereby mixing the molded material well.

The transfermix screw press has a certain market share compared to a pin worm, especially when the screw press is to be short. The disadvantage of this construction of the mixing zone is its high production demands.

SUMMARY OF THE INVENTION

These drawbacks are largely eliminated by an extruder screw for the processing and production of rubber and thermoplastics, consisting of a housing consisting of a housing having an inlet opening at its inlet end and an outlet opening at the outlet end, with a worm with an outer A drive unit is connected to the thread to which the body has two mixing and homogenizing parts arranged one behind the other. The mixing part is formed by a cylindrical zone and the homogenizing part is formed by a conveying mixing zone.

Pins are provided in the housing in the region of the cylindrical zone, extending into the processing interior of the housing.

According to a preferred embodiment, the transport mixing zone is located downstream of the cylindrical zone from the inlet end to the outlet end of the housing.

- 1 GB 284331 B6

According to a further preferred embodiment, a draw-in zone is formed in the body upstream of the roller zone and a pressure-increasing zone is formed downstream of the conveyor mixing zone.

According to another preferred embodiment, the total length of the sleeve is 10 times greater than the diameter of the screw. The length of the draw-in zone is 3 times the diameter of the screw. The length of the cylindrical zone is 1.5 to 2 times greater than the screw diameter. The length of the conveyor mixing zone is 2 to 2.5 times greater than the diameter of the screw and the length of the pressure boosting zone is 3 times greater than the diameter of the screw.

According to a further preferred embodiment, the pins are disposed in the direction of the longitudinal axis of the housing in one to five rows, in particular in two rows, and extend radially through the housing.

According to a further preferred embodiment, an internal thread is formed in the housing in the region of the conveying mixing zone. The angle opening in the direction of movement of the workpiece between the female thread and the external screw thread is greater than or equal to 105 ° in the region of the conveying mixing zone.

The main advantage of the proposed solution is that a new generation of mixing and homogenizing extruding screw presses is created, which at the same mixing quality and at the same screw speed have a worm drive power input of 50% less and the throughput of the molded material is increased by 60-100%.

Another advantage is the reduction of the drive torque by 50%, which leads to a great reduction in drive costs and a reduction in the length of the conveyor mixing zone with the same mixing quality.

Overview of the drawings

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in more detail by means of a drawing, in which a longitudinal section of a screw extruder is shown schematically.

DETAILED DESCRIPTION OF THE INVENTION

The extruder screw for processing and production of rubber and thermoplastics consists of a body 1, which is formed by a sleeve 2, in which a screw 6 is rotatably placed. At the inlet end of the sleeve 2 an outlet opening 4 for exiting the molded mixture. The screw 6 is connected to the drive unit 5 at the inlet end of the housing 2 to rotate the screw 6 about its longitudinal axis.

The body 1 has two downstream mixing and homogenizing portions, wherein the mixing portion is formed by a cylindrical zone 7 and the homogenizing portion is formed by a conveying mixing zone 8. The housing 2 is therefore divided into an inlet direction from the inlet end towards the outlet end and zone 9 followed by a cylindrical zone 7, followed by a transport mixing zone 8, followed by a pressure-increasing zone 10. The worm 6 has a geometry in the drawing zone 9 which is suitable for drawing the plasticized molded material into the housing 2. In the cylindrical zone 7, two rows of pins 11 are disposed in the direction of the longitudinal axis of the housing 2 and extend radially through the housing 2 and extend into the processing interior 14 of the housing 2. More than two rows of pins 11 may be spaced in the cylindrical zone. In view of the cost / quality relationship of the molded mixture, it is preferable that one to five rows of pins 11 are located in the cylindrical zone 7. In the cylindrical zone 7, the external threads 12 of the screw 6 are interrupted in the plane of the pins 11. with TL pins

-2GB 284331 B6

In the conveying mixing zone 8, the angles opening in the direction of movement of the workpiece between the external threads 12 of the screw 6 and the internal threads 13 of the housing 2 are greater than or equal to 105 °.

In the pressure-increasing zone 10, the geometry of the screw 6 is selected such that the crushing pressure is increased to the necessary tool pressure.

In addition to this exemplary embodiment, it is also possible to provide other high-performance extruder screw designs. In a further exemplary embodiment, the conveying mixing zone 8 may be positioned upstream of the cylindrical zone 7, for better mixing and homogenization results.

The total length of the sleeve 2 is 10 times greater than the diameter of the auger 6. The length of the pulling zone 9 is 3 times greater than the diameter of the auger 6. The length of the cylindrical zone 7 is 1.5 to 2 times greater than the diameter of the auger 6. up to 2.5 times the diameter of the auger 6. The length of the pressure boosting zone 10 is 3 times the diameter of the auger 6.

Irrespective of these data, additional zones, such as degassers or kneaders, may be provided upstream or downstream of the conveyor mixing zone 8 or between the conveyor zone 7 and the conveyor mixing zone 8 as desired.

PATENT CLAIMS