RU2540666C1 - Device for polymer melt degassing (versions) - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: device for polymer melt degassing contains casing with input and output channels for polymer melt, gas exhaust channels, work chamber, in which two chevron gears are installed, they are in engagement and can rotate. At that each gear has limiting elements installed on the shaft and interfaced with its end faces. At that each of the limiting elements is made with diameter exceeding diameter of dedendum circle of toothed rim, but below diameter of pitch line of the gear, and side sections of the limiting elements are made with melt pushing off grooves, and interface with casing from side of the output channel.

EFFECT: improved reliability and assurance of free gas exhaust from casing.

6 cl, 9 dwg

Description

The field of technology.

The invention relates to equipment for the processing of polymeric materials by extrusion.

State of the art

The prior art design of a screw extruder for producing polymer melt (analogue see US 4088307, publ. 05/09/1978, MKI2 B29B 1/10), equipped with a housing with a gas outlet and two screws installed in the housing. Moreover, the shaft of each of the screws is provided with a surface area with hemispherical protrusions located opposite the aforementioned hole. During processing, the polymer melt falling between the protrusions is compressed, so that the gas contained in the mass of the polymer melt breaks out and exits through the gas outlet.

The disadvantages of the above extruder include the bulkiness of the structure, as well as clogging with a polymer melt of the gas outlet.

As the closest analogue, a device has been adopted for softening and homogenizing rubber mixtures (see US 6361200 B2, IPC B01F 7/00, publ. March 26, 2002), which includes a housing equipped with: an inlet channel; output channel; a working chamber made in the form of a figure of eight, in which two chevron or helical gears are mounted for rotation, engaged with each other by teeth; gas outlet channels made from the input channel opposite the zones where the gear teeth do not interact with each other. The above device is compact, has a relatively simple design, due to the performance on the basis of a gear pump.

The disadvantage of this device is that rubber mixtures can accumulate at the ends of the gears, squeeze and clog the gas outlet channels, which leads to a violation of the degassing process.

Disclosure of invention

The objective of the invention is to improve the device for the degassing of polymer melt, which would be devoid of the above disadvantages.

The technical result, to which the invention is directed, is to increase the reliability of the device, providing unimpeded removal of gases from the housing.

The set of features of the claimed device for degassing a polymer melt is in a causal relationship with the achieved technical result and is presented in an independent claim.

The specified technical result according to the first embodiment is achieved in a device for degassing a polymer melt, comprising a housing provided with inlet and outlet channels for the polymer melt, gas outlet channels, a working chamber, in which two chevron gears are engaged that are engaged with each other , according to the invention, each of the gears is equipped with restrictive elements mounted on the shaft and mating with its ends, while each of the restrictive elements made with a diameter exceeding the diameter of the circumference of the depressions of the ring gear, but not exceeding the diameter of the pitch circle of the gear, and the side sections of the restrictive elements are made with melt repelling grooves and are coupled to the housing from the outlet channel.

The restrictive elements associated with the ends of the gears can be made cylindrical in the form of disks.

The lateral sections of the restrictive elements are associated with the body of the housing covers.

The specified technical result according to the second embodiment is achieved in a device for degassing a polymer melt, comprising a housing provided with inlet and outlet channels for the polymer melt, gas outlet channels, a working chamber in which two helical gears are installed for rotation, which are engaged with each other , according to the invention, each of the gears is equipped with a restrictive element mounted on the shaft and mating with its end face, while the restrictive element is made diameter ohm greater than the root circle diameter of the gear ring, but not exceeding the pitch diameter of gear circumference, and located near the gas outlet channel and the lateral portions of the restriction members are made with repellent melt grooves and are associated with side outlet housing.

The restrictive element associated with the end face of the gear may be made cylindrical in the form of disks.

The lateral sections of the restrictive elements are associated with the body of the housing cover.

Brief Description of Explanatory Figures

Figure 1 - shows the proposed device;

figure 2 - shows the proposed device without a cover;

figure 3 - shows the details of the proposed device with chevron gears;

figure 4 - shows a chevron gear with restrictive elements at the ends;

figure 5 - depicted in meshing chevron gears located on one of the housing covers;

6 - schematically shows the proposed device in section;

Fig.7 - shows a section aa of Fig.6 with chevron gears;

Fig.8 - shows a section aa of Fig.6 with helical gears;

Fig.9 is an enlarged fragment of figures 7, 8.

The above figures show:

1 - housing;

2 - input channel;

3 - output channel;

4 - a working chamber;

5 - chevron gear;

5a - helical gear;

6 - chevron gear;

6a - helical gear;

7 - gear shaft;

8 - gear shaft;

9 - housing cover 1;

10 - hole;

11 - hole;

12 - gas outlet openings;

13 - gas outlet channels;

14 - restrictive elements;

14a is a peripheral portion of a restriction member;

14b is a side portion of the restrictive element;

15 - groove;

16 - ledge.

It should be understood that those skilled in the art will be able to propose other embodiments of the invention and that some of its details can be changed in various other aspects without departing from the spirit and scope of the present invention. Accordingly, the explanatory figures 1-9 and a detailed description of a device for degassing a polymer melt are illustrative, but not restrictive.

The best embodiments of the invention

The device for degassing a polymer melt, shown in figures 1-9, contains a housing 1, in which are made: the input channel 2 for the receipt of the polymer melt; output channel 3 for output of the polymer melt; the working chamber 4 with installed gears 5 and 6, placed on the respective shafts 7 and 8.

The housing 1 can be made of several parts, motionlessly interconnected. In a specific embodiment, the housing 1 includes a central portion in which the working chamber 4 is made, and two oppositely located covers 9 in which openings 10 and 11 are made for mounting the shafts 7 and 8 of the corresponding gears 5 and 6, the openings 12 and the channels 13 gas outlet.

The working chamber 4 is made in the shape of a figure-shaped figure-eight with curved surfaces covering most of the circumference of the teeth of the gears 5 and 6, which are engaged with each other.

The teeth of the gears 5, 6 serve as scrapers, stratifying the polymer melt into many thin strips, from which the gas breaks out and is removed through the channels 13 and the gas outlet 12.

According to the first embodiment, gears 5 and 6 are made chevron. At both ends of the shafts 7, 8, restrictive elements 14 are mounted that are mated without a gap with the ends of the gears 5, 6. Moreover, the diameter of each of the restrictive elements 14 exceeds the diameter of the circumference of the valleys of the ring gear, but does not exceed the diameter of the pitch circle of the gear 5, 6, with which he is paired. The restrictive elements 14 from the side of the ends of the gears 5, 6 overlap with their peripheral section 14a the grooves between the teeth of the said gears 5, 6, preventing the polymer melt from entering the channels 13 and the gas outlet 12. Thus, the openings 12 and the gas outlet channels 13 are not clogged by the melt and remain clean.

The restriction elements 14 can be made of individual cylindrical parts with central holes for accommodating the shafts 7, 8. The restriction elements 14 can be connected to the gears 5, 6 by means of an integral, for example, welding connection, or detachable connection by means of fasteners, for example, bolts. It is possible that each of the gears 5, 6 can be made integral with the restrictive elements 14.

In a specific embodiment, the restrictive elements 14 are made in the form of disks mounted on shafts 7, 8 and are permanently connected to the ends of the gears 5, 6 by means of a welding joint.

Gears 5 and 6 can be made of the same diameter, as shown in the explanatory figures, and of different diameters (not shown in the figures). In the case of gears 5, 6 of different diameters, the restrictive elements 14 are made in accordance with the dimensions of the gears 5, 6, with which they are mated without a gap or connected.

The aforementioned gas outlet channels 13 are made in the covers 9 of the housing 1 from the side of the inlet channel 2. In a specific embodiment, the gas outlet channels 13 are made in a circular arc.

To prevent the melt from entering the gas outlet openings 12 outside the restriction elements 14, the side sections 14b of the said restriction elements 14 contain melt repelling grooves 15 and are connected (without a gap) to the housing 1 from the outlet channel 3 (in the high pressure zone). In a specific embodiment, the side portions 14b of the restriction elements 14 are associated with the body of the covers 9 of the housing 1, in particular, with local protrusions 16 made along an arc of a circle. Said protrusions 16 are as close as possible to the side portions 14b in order to avoid a gap between them, i.e. the protrusions 16 and the side sections 14b, while the protrusions 16 should not impede the rotation of the restrictive elements 14 with the gears 5, 6. The grooves 15 are made right-side and left-sided respectively to the direction of the teeth of the gears 5, 6. For example, if the restrictive element 14 is paired with the end face of the gear with the right teeth, then the groove 15 is made right-handed, if the restrictive element 14 is paired with the end face of the gear with left-hand teeth, then the groove 15 is made left-handed.

The input channel 2 is performed with a height h1 not exceeding the width of the rim h2 of the gear 5, 6, which prevents the polymer melt from entering the channels 13 and the gas outlet 12. The input channel 2 may be made of round or rectangular cross-sectional shape.

According to a second embodiment, the gears are helical 5a and 6a. In this case, each of the helical gears 5a, 6a is provided with one restrictive element 14 mounted on the corresponding shaft 7, 8 and mating with one of its end faces. Moreover, the restrictive element 14 is made with a diameter exceeding the diameter of the circumference of the depressions of the ring gear, but not exceeding the diameter of the pitch circle of the gear 5a, 6a with which it is mated. The aforementioned restriction elements 14 are located near the gas outlet channel 13. And the side sections 14b of the restriction elements 14 are associated with the body of the cover 9 of the housing 1, in particular with the previously mentioned local protrusions 16.

The channels 13 and openings 12 of the gas outlet in the device with helical gears 5a, 6a are located only on one side of the housing 1.

Next, the operation of the device with chevron gears 5 and 6 will be described.

The polymer melt entering through the input channel 2 into the cavity 4 of the housing 1, is captured by the teeth of the rotating gears 5, 6 and moves along the cylindrical sections of the walls of the working chamber 4 into the channel 3 of the output of the polymer melt. Part of the polymer melt moves along the grooves between the teeth to the ends of the gears 5, 6 and abuts against the peripheral sections 14a of the restriction elements 14 overlapping the lower part of the said grooves. Thus, the peripheral portions 14a prevent the polymer melt from entering the channels 13 and the gas outlet 12. In the high pressure zone from the side of the output channel 3, the melt penetrated between the side portions 14b of the adjacent restrictive elements 14 of the gears 5 and 6 is discharged along the grooves 15 into the area between the gear teeth 5, 6.

In the particular case of the implementation of the device 1, gas can be removed from the channels 13 by means of a vacuum pump connected to the holes 12.

The proposed device is characterized by increased reliability, since the channels 13 and the gas outlet 12 are not clogged by the processed polymer melt and remain clean, as a result, the degassing quality of the polymer melt is improved. Moreover, the device is suitable for processing a wide range of polymeric materials, such as high and low pressure polyethylene, polystyrene, polypropylene, rubber mixtures, etc.

Claims (6)

1. A device for degassing a polymer melt, comprising a housing provided with inlet and outlet channels for the polymer melt, gas outlet channels, a working chamber, in which two chevron gears are engaged that are engaged with each other, characterized in that each of the gears is equipped with restrictive elements mounted on the shaft and mating with its ends, while each of the restrictive elements is made with a diameter exceeding the diameter of the circumference of the depressions of the ring gear, but not greater than the operation gear pitch circle diameter and the side portions of the restriction members are made with repellent melt grooves and are associated with side outlet housing. 2. The device for degassing a polymer melt according to claim 1, characterized in that the restrictive elements are cylindrical or in the form of disks. 3. The device for degassing a polymer melt according to claim 1, characterized in that the side portions of the restrictive elements are associated with the body of the housing covers. 4. A device for degassing a polymer melt, comprising a housing provided with inlet and outlet channels for the polymer melt, gas outlet channels, a working chamber in which two helical gears are mounted for rotation, which are engaged with each other, characterized in that each of the gears is equipped with a restrictive element mounted on the shaft and mating with its end face, while the restrictive element is made with a diameter exceeding the diameter of the circumference of the depressions of the ring gear, but not exceeding the diameter p of the pitch circle of the gear, and is located near the gas outlet channel, and the side sections of the restrictive elements are made with melt repelling grooves and are coupled to the housing from the outlet channel side. 5. A device for degassing a polymer melt according to claim 4, characterized in that the restrictive elements are cylindrical or in the form of disks. 6. A device for degassing a polymer melt according to claim 4, characterized in that the side portions of the restrictive elements are associated with the body of the housing cover.

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