RU2002626C1 - Extruder for processing and production of raw rubber and thermoplastics - Google Patents

Abstract

Usage: the processing of rubber and thermoplastic plastics by their mixing and homogenization. SUMMARY OF THE INVENTION: The extruder has a mixing and transfer zone. The mixing zone is made with radially located pins and interrupted in the pins by the ridge of the screw cutting turns. In the transfer zone, the screw is made with a continuous reduction in the winding volume to zero and further increasing to the maximum. having an increase in inter-turn volume from zero to a maximum, followed by a decrease to zero. Throttle pins are located with the possibility of radial adjustment in the region of the maximum inter-turn volume of the body cutting. This solution allows to increase productivity by 60 - 100% while maintaining the quality of the mixture and using half drive torque of 7 glf. 4 id

Description

The invention relates to the processing of polymers and can be used in the chemical industry.

An extruder for processing and manufacturing rubber and thermoplastic plastics is known, comprising a housing with inlet and outlet openings, a drive for the housing located in the working chamber of the housing rotatably relative to the longitudinal axis of the screw, the extruder having two mixing and homogenizing transfer zones arranged one after another, one of which it is made in the form of a pin cylindrical zone with pins radially entering the working chamber of the housing and interrupted in the area of the pins by the crests of the screw cutting turns.

This extruder is characterized by a very high productivity and a good homogenizing effect on the processed material and, in addition, it provides the possibility, with the same number of revolutions of the screw, to increase the throughput capacity of the material per unit time, in comparison with traditional extruders with cold loading and a screw with a cutting part.

The disadvantage of the extruder is its significant structural length.

The closest in technical essence to the proposed solution is an extruder for processing and production of rubber and thermoplastic plastics, comprising a housing with inlet and outlet openings, a drive for the housing located in the working chamber with the possibility of rotation relative to the longitudinal axis of the screw, the extruder having two another mixing and homogenizing transfer zones, one of which is made in the form of a pin cylindrical zone with throttle radially entering the working chamber of the housing pins.

The presence of throttle pins in a known extruder allows control of the flow of recyclable material outside the extruder.

The disadvantage of the extruder is also a significant structural length, insufficient productivity and insufficient ability to adjust the plasticization of the material depending on its properties, which limits the technological capabilities of the extruder.

The objective of the invention is to increase the productivity of the extruder and expand its technological capabilities.

The object is achieved in that in an extruder for processing and manufacturing rubber and thermoplastic plastics,

comprising a housing with inlet and outlet openings, a drive for the housing located in the working chamber with the possibility of rotation relative to the longitudinal axis of the screw, the extruder having two mixing and homogenizing transfer zones arranged one after the other, one of which is made in the form of a pin cylindrical zone with radially pins entering the working chamber of the housing and interrupted in the area of the pins by the crests of the screw cutting turns, and protruding into the working chamber are installed at the outlet of the transfer zone in the housing

5 of the housing, the throttle pins according to the invention, in the transfer zone from the inlet to the outlet auger, are made with a continuous decrease in the inter-turn volume to a maximum value, and in the housing along the inner surface there are continuous turns located, screwed relative to the longitudinal axis of the extruder, having from the inlet part of the zone up output increase

5 of the inter-turn volume from zero to a maximum value, followed by a decrease to a zero value, while in the region of the maximum inter-turn volume, the body cuts are located with the possibility. radial adjustment throttle pins located in the intervals of the turns of the housing.

In addition, the pin cylindrical zone is located in front of the transfer zone.

With a preferred extruder length of 10 screw diameters, the length of the feed zone located in front of the mixing and homogenization zones is selected to be three

For screw diameters, the pin cylindrical zone has a length of one and a half to two screw diameters, the transfer zone has a length of up to two and a half screw diameters, and the length of the pressure zone located at the exit of the extruder is chosen to be equal to three screw diameters. One to five rows of pins are located in the pin cylindrical zone.

In the transfer zone

0 of the screw and the casing are arranged with the formation between their ridges of angles of at least 105 ° and without the formation of additional angles of up to 90 °. The extruder can be equipped with additional throttle pins located at the outlet end of the extruder.

The extruder may be equipped with actuators of a mechanical, pneumatic or hydraulic type for radially moving the throttle pins to the entire depth of the turns of the body cut.

In the input and output parts of the transfer zone, the number of entries and the number of crests of the turns of the screw and the housing are constant and independent of the cross-sectional area of the turns of the housing or the screw.

Thanks to the specific design of the transfer zone and the specific placement of the throttle pins, it is possible with the same mixing quality and the same number of revolutions of the screw to reduce the drive power of the extruder to 50% and increase the throughput of the material to 60-100%.

This 50% reduction in drive torque in the manufacture of the extruder results in a significant reduction in transmission costs. Moreover, by connecting the pin cylinder and the transmission part of this design, the design length of the mixing zone, necessary for the same quality of mixing, can be reduced by about 50%, compared with an extruder operating solely on the principle of a pin cylinder.

Due to the placement of interchangeable throttle pins extending radially into a part of the transfer zone of the extruder body with a maximum inter-turn cutting volume, the proposed extruder can be adjusted to process various rubber mixtures. Thus, by varying the penetration depth of the throttle pins, the cutting of the body and the working chamber of the extruder can arbitrarily and taking into account the mixture make a preliminary selection of the plasticization productivity.

Thus, in comparison with the well-known extruders still belonging to this genus, in addition to the screw speed and temperature at various stages of the process, one can resort to a further freely chosen process parameter.

The invention can be explained on the basis of exemplary embodiments and with reference to FIG. 1-4.

In FIG. 1 shows a longitudinal section through a single screw extruder with throttle pins in the transfer zone; in FIG. 2-4 is a graphical representation of the experimental results with the extruder of the proposed design, in comparison with a traditional pin extruder.

In FIG. 1 is a schematic longitudinal sectional view of a single screw extruder 1. The body 2 of the extruder 1 has an inlet 3 for feeding the extrudable material and an outlet 4 for the exit of the mixed and homogenized material. A screw 6 is located in the housing 2 and connected to the drive 5. It is mounted rotatably relative to its longitudinal axis. The extruder 1 has two mixing consecutive 7 and a homogenizing transfer

0 zone 8. At the inlet to the extruder 1, an input zone 9 is located, and at the output, a pressure zone 10.

The screw 6 of the extruder 1 has in the input zone 9 a screw geometry suitable for

5 in order to tighten the material introduced through the inlet 3 into the extruder 1 in a known manner and plasticize it.

Downstream of this input zone 9, a mixing pin is provided

0 is a cylindrical zone 7 in which two rows of pins 11 protrude radially through the housing 2 of the extruder 1 in the direction of the axis of the screw b. In this zone 7, the crests of the turns 12 of the screw 6 are interrupted in a known manner in the plane

5 pins 11 in order to avoid collision with pins 11.

In the transfer zone 8 in the housing along the inner surface there are made continuous turns 13 of a screw located differently relative to the longitudinal axis of the cutting extruder, having from the input part of the zone to the output increase the inter-turn volume from zero to the maximum value, followed by a decrease to

5 zero value. In the transfer zone 8 in the working chamber 14 of the extruder body 1, the screw 6 has a cut 15 made with a continuous decrease in the inter-turn volume to a zero value and a subsequent increase in the inter-turn volume to a maximum value. In the region 16 of the maximum inter-turn volume of the body cutting, throttle pins 17 are located in the spaces of the turns 13

5 buildings. In the pressure zone 10, the screw 6 is located in a sleeve 18 mounted in the housing. For thermostatting of the extruder, holes 19 are provided. In the transfer zone 8, the screw 6 is placed in

0 sleeve 20, on the inner surface of which are located turns 13.

Downstream from the pin cylindrical zone 7 in the transfer zone 8 in this embodiment, the angles between the ridges 5 of the turns 15 of the screw b of the extruder 1 and the ridges of the turns 13 of the body of the extruder 1 are greater than or equal to 105 ° and do not form complementary to 90 ° angles. The transfer zone 8 can be divided into input and output parts, both parts being separated

from each other by entering the body with the highest profile height. In this transfer zone 8. in addition, the number of entries in the input and output parts is constant, due to which the number of crests of turns in the input, respectively output parts, is independent of the cross section of the turns in the housing 2 and the screw 6.

In addition to this embodiment, other implementation possibilities for this pin transfer extruder can also be imagined. Thus, for example, the transfer zone 8 may also be located upstream of the cylindrical pin zone 7, although the above embodiment provides better mixing and homogenization results. In addition, it should be noted here that the pin cylindrical zone 7 fulfills its task of mixing and homogenizing also with the number of rows of pins 11 exceeding two. With regard to the cost-to-mix ratio, it is most advantageous to equip the pin cylinder zone 7 with one to five rows of pins 11

The preferred length of the individual zones of the extruder is, when the extruder has a length of 10, screw diameters (D) of approximately 3D for the entry zone 9, from 1.5 to 10 D, preferably from 1.5 to 2 D for the pin cylindrical zone 7, from 2 to 2. 5 D for the transfer zone 8 and about 3 D for the pressure boost zone

Regardless of these indications, depending on the need, however, additional process zones may also be located before, after or between the pin cylindrical 7 and the transfer 8 zones. for example, degassing or kneading zones.

In FIG. 1 shows an extruder 1 with throttle pins 11 in a transfer structural member. The entry zone 9 of this extruder corresponds to a conventional cold-loading extruder and has a screw length ratio (D) to screw diameter of three.

Behind the entry zone 9, there is a portion of the extruder, which is equal in length to the total length 6 D, on which there is a pin cylindrical zone 7 with two consecutive planes with pins 11 Downstream of the pin cylindrical zone 7, a transfer zone 8 with a length of approximately 2 is provided D and pressure zone 9 with a length of approximately 1.5 O

As noted above, the rise of the turns 15 of the screw 6 and the turns 13 of the sleeve 20 of the transfer zone 8 is selected so that the ridges

turns between the screw and the sleeve form an angle equal to or greater than 105 °. The result of this, in a preferred manner, is that the extrudate pass through

the transfer zone due to the resulting on the basis of this large number of points of intersection of the ridges of the turns of the screw and the sleeve for one revolution of the screw 6 is subjected to an intensive cutting process.

0 In contrast to the turns of the screw 15, the turns of the sleeve 20 in the transfer zone do not have interruptions. Moreover, they spin continuously and continuously from the inlet of the transfer zone to its outlet

5 parts, approximately increasing, respectively decreasing in a spiral form around the imaginary longitudinal axis of the extruder.

In the first third of the transfer zone, the diameter of the core of the screw 6 increases from the maximum height of the profile to the outer diameter, i.e., the inter-turn volume of the screw 6 drops from the maximum value in the input part to zero. The inter-turn volumes of bushings 20 have the opposite tendency. Thereby, the passage volume for the extrudate is kept constant in the axial and radial directions of transport. Forced based

0 of these circumstances, there is a 100% exchange of the extrudate between the screw 6 and the sleeve 20 of the extruder body.

In the output portion of the transfer zone according to FIG. 1, equal to about 1.4 D, the inter-turn volume of the screw 6 is continuously increasing and in the sleeve 20 it is continuously decreasing, and in turn, the total inter-turn cutting volume is kept constant for the extrudate

0 screw 6 and sleeve 20.

Studies have shown that, in particular, when processing highly viscous mixtures of natural rubber, preliminary plasticization of the extruder in the pin zone 7

5 at low shear drops before intensive plasticization work in the transfer zone affects both productivity increase and positively on the pulsation characteristic of the ex0 labor

In addition to the number of revolutions of the screw 6 and the temperature of the technological parts, the extruder has the following process parameter, which can be freely preselected and extends the versatility of the extruder in relation to the ability to process a wide range of different rubber mixtures.

In this embodiment, at the end of the first third of the transfer zone 8, there is a throttle element having throttle pins 17 distributed symmetrically around the circumference of the transfer structural element, which radially enter the turns 13 of the sleeve 20 of the transfer zone 8 and can change the inter-turn volume of the sleeve 20 in this zone from the maximum value to zero.

By means of these throttle pins 17, which are manually manually mechanically, pneumatically or hydraulically actuated from the outside by means of actuators 21, the plasticization performance can be arbitrarily set, respectively, the friction energy converted to the extrusion zone in the transfer zone.

The throttle pins 17, among other things, should be attributed to the fact that using a pin transfer extruder for the first time it was possible to process the quality of rubber mixtures, which until now have not been processed with sufficient homogeneity using cold loading extrusion, even by using specially optimized cylindrical pin extruders . This refers to the qualifications of natural rubber, for example, for the manufacture of lugs for armored targets, as well as mixtures for treads with the same base polymer for truck tires.

If we combine the test results achieved so far with an extruder, it can be established that, in comparison with a pin cylindrical extruder with small viscosity mixtures of synthetic rubber up to viscosities from 55 to 60 MLI + 4 (100 ° С), an increase in productivity from 25 to 50%, with a decrease in specific energy to 20%.

With highly viscous difficult-to-process natural rubber qualities between 90 and 120 MLI + 4 (100 ° С), the advantages are even more relevant, since in the case of a pin cylindrical extruder, the extrudate homogeneity limit, as revealed, is already reached at approximately 800- 1000 kg / h and thus, in some cases, when using a pin transfer extruder, doubling the productivity is possible.

In FIG. 2-4 show the results of experiments in a graphical representation.

which were obtained using an extruder according to the prior art (dashed curves) and a laboratory pin transfer extruder (continuous curves 5) of comparable size. A mixture of natural rubber NK 90-95 MLI + 4 (100 ° C), known as a highly viscous and especially difficult to process mixture, was used as an extrudate. In all three images, a vertical stroke with hatching indicates the number of revolutions equal to 25 revolutions per minute, to which a conventional extruder with the proper quality could process such a rubber mixture.

5 in FIG. 2, rubber release is plotted depending on the number of revolutions of the screw, while in FIG. 3 shows the temperature of the mass and in FIG. 4 - specific energy consumption per 1 kg of extrudate, respectively, as

0 function of the screw speed. A comparison of these three graphs shows that, using the concept of an extruder proposed here, with excellent effect on mixing and homogenization

5, high extrudate production is possible at an acceptable extrudate temperature and substantially reduced energy consumption.

In addition, the fact that

0 there were no problems with the porosity of the product along the profile occurring in the case of a pin cylindrical extruder already in the lower productivity region.

5 In conclusion, it should be pointed out that the proposed pin cylindrical extruder can be used with or without throttle pins in the gear unit. although in the case of an optimal design, throttle pins should not be discarded. Finally, by positioning them, the extruder can be adjusted to a wide variety of rubber mixtures and their processing parameters.

5 and thereby universally usable. In an improved embodiment, the present throttle pins may also be located at the end of the extruder downstream, approximately at the end of the pressure zone 10.

(56) US Pat. No. 4,178,104, cl. B 29 B 1/06, 1979.

EP patent No. 00822494, CL B 29 F 3/03, 1983.

Claims (8)

1. EXTRUDER FOR THE PROCESSING AND PRODUCTION OF RUBBER AND THERMOPLASTIC PLASTICS, comprising a housing with inlet and outlet openings, a drive for the housing located in the working chamber with the possibility of rotation relative to the longitudinal axis of the screw, the extruder having two mixing and homogenizing transfer zones, one of which is made in the form of a pin cylindrical zone with radially The pins entering the working chamber of the housing and interrupted in the area of the pins by the ridge of the screw cutting turns, and at the output of the transfer zone, throttle pins protruding into the working chamber of the housing are installed, characterized in that the transfer zone from the inlet to the output screw is made with continuous a decrease in the inter-turn volume to zero and the subsequent increase in the inter-turn volume to a maximum value, and continuous turns of a helical relation are made in the housing along the inner surface along the longitudinal axis of the cutting extruder, having from the input part of the zone to the output increase in the inter-turn volume from zero to a maximum value, followed by a decrease to a zero value, while in the region of the maximum inter-turn volume of the body cutting, throttle pins located in between turns of the case. 2. An extruder according to claim 1, characterized in that the pin cylindrical zone is located in front of the transfer zone. 3. The extruder according to claim 1, characterized in that, with a preferred length of ex a labor equal to 10 auger diameters, the length of the feed zone located in front of the mixing and homogenization zones is selected to be 3 auger diameters, the pin cylindrical zone has a length of 1.5-2 auger diameters, the transfer zone is 2.5 auger diameters, and the length of the increased zone the pressure at the exit of the extruder is selected equal to 3 screw diameters. 4. An extruder according to claims 1 to 3, characterized in that from one to five rows of pins are located in the pin cylindrical zone. 5. An extruder according to claims 1 to 3, characterized in that in the transfer zone the turns of the auger and the body are arranged to form at least 105 angles between their ridges and without forming up to 90 additional angles. 6. An extruder according to claims 1 to 4, characterized in that it is provided with additional throttle pins located at the output end of the extruder. 7.Extruder for PP. 1 and 6, characterized in that it is equipped with actuators of a mechanical, pneumatic or hydraulic type for radially moving the throttle pins to the entire depth of the turns of the cut of the housing. 8. Extruder 1-7, characterized in that in the input and output parts of the transfer zone, the number of entries and the number of ridges of the turns of the screw and the casing is constant and does not depend on the cross-sectional area of the turns of the casing or auger. Priority on points: 04/29/91 - according to claims 1, 6-8; 12.14.90-according to claims 2-5. T m u I kg / W 2000 FIG. g