JP2000343585A - Backwashing method of screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand the apertures of a mesh member to perfectly remove unnecessary matter by passing a backwashing molten resin through the cylindrical screen parts constituting a screen from the inside to the outside. SOLUTION: In a backwashing method of a screen, a molten resin is passed through a cylindrical screen part 7 from the outside to the inside to remove unnecessary matter 50 and subsequently passed through the cylindrical screen part 7 from inside to the outside. By this constitution, the apertures 7bb of a mesh member 7b are expanded to remove the unnecessary matters engaged with the apertures 7bb.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of backwashing a screen, and more particularly to a method of backflowing a molten resin from the inside to the outside of each cylindrical screen after filtration, and discharging the molten resin to the outside, thereby reducing the mesh. The present invention relates to a novel improvement for removing an unnecessary object by opening a body opening with a liquid flow.

[0002]

2. Description of the Related Art FIG. 5 shows a structure disclosed in Japanese Patent Application Laid-Open No. Hei 10-244576, for example, as a screen of this type used conventionally. That is, what is indicated by reference numeral 3 in FIG. 5 is a casing of the screen exchange device 1, and a slider 5 detachably provided in the cavity 2 in the casing 3 has a plurality of cylindrical members along its outer peripheral shape. The screen portions 7 are provided annularly at predetermined angular intervals, and each cylindrical screen portion 7 is provided.
Constitute the screen 7A. As shown in FIG. 6, each of the cylindrical screen portions 7 is formed of a mesh body 7b having a large number of mesh openings on the outer periphery of a cylindrical guide member 7a. Molten resin from the machine penetrates from the outside to the inside of each tubular screen portion 7 of this screen 7A, and at the time of this penetration, unnecessary matter is engaged with each opening on the surface of each tubular screen portion 7 and is captured. . The molten resin that has passed through the screen 7A passes through the confluence portion 11 and passes through the second resin through hole 10 to the outside (die side).
To be made into a strand.

[0003]

The conventional screen is
Because of the above configuration, the following problems exist. That is, it is difficult to remove unnecessary substances such as foreign substances adhering to the surface of each cylindrical screen portion of the screen, and there is no other way but to replace each cylindrical screen portion, which is not suitable in terms of cost and resource saving. In addition, as a conventional configuration different from the configuration shown in FIG.
A flat plate type screen disclosed in Japanese Patent Publication No. 11 is also used, and a method of back-washing the flat plate type screen after filtration by allowing a liquid to pass through the flat plate type screen in a direction opposite to a resin passing direction is also available. Although it seems to have been adopted, the opening could not be widened because of the flat plate type, and it was extremely difficult to remove unnecessary objects.

[0004] The present invention has been made to solve the above-mentioned problems, and in particular, by discharging a liquid from the inside to the outside of a cylindrical screen portion after filtration in a reverse direction and discharging the liquid to the outside. It is another object of the present invention to provide a method of backwashing a screen in which an opening of a mesh body is expanded by a molten resin flow to remove unnecessary portions.

[0005]

A method of backwashing a screen according to the present invention is directed to a screen having a plurality of cylindrical screen portions arranged in a ring shape for removing unnecessary substances in a molten resin. The unnecessary material is filtered by passing the molten resin from the outside to the inside of the screen part, and further, the molten resin is passed from the inside to the outside of the screen part and discharged to the outside by passing the molten resin to the outside. The method is a method of expanding an opening of each mesh body and removing the unnecessary object engaging with the opening from the cylindrical screen portion.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the method for backwashing a screen according to the present invention will be described below with reference to the drawings. Note that the same or equivalent parts as those in the conventional example will be described using the same reference numerals. In FIG. 1, what is indicated by reference numeral 3 is a casing of the screen changer device 1. Between the first opening 20 and the second opening 21 of the casing 3, a first flow path 22 and a second flow path 23 are provided. Formed,
First and second cavities 24 and 25 are connected to the respective flow paths 22 and 23.

A screen breaker plate 5 is provided in each of the cavities 24, 25, and a plurality of cylindrical screen portions 7 are provided in the screen breaker plate 5 in a ring shape. Each of the cylindrical screen portions 7 has a coaxial combination structure of a guide member 7a and a mesh body 7b shown in FIG.

Each of the cylindrical screen portions 7 is provided annularly at predetermined angular intervals along the annular shape of the screen breaker plate 5, and as shown in FIG. The first, second, and third slide bars 30, 31, and 32 are tie bars 33 and nuts 3.
4 is configured so as to be freely disassembled and assembled in the axial direction.

A second slide bar 31 is provided between the first and third slide bars 30, 32.
A mounting portion 7c of the cylindrical screen portion 7 is provided in a mounting portion 41 formed in a base channel 40 of a base portion 31a of the slide bar 31 in a screw type or a fitting type, and a guide member for the cylindrical screen portion 7 is provided. The mesh member 7a and the mesh body 7b are located in a ring-shaped screen gap 43 that communicates with the operation input section 42 into which the molten resin is input during operation. Further, at an end of the screen breaker plate 5 at a position outside the first slide bar 30, a discharge groove 44 for discharging both unnecessary matter such as foreign matter and molten resin for discharge is formed.
An adjusting nozzle 44 for adjusting a degree of discharging the unnecessary matter is connected to a tip of the discharging groove 44.

Next, the operation will be described. First, FIG.
In the operation state, when the molten resin melt-kneaded is supplied from the extruder (not shown) from the operation input section 42, the molten resin is supplied from the screen gap 43 to the cylindrical screen portion 7
Through the mesh member 7b and the guide member 7a, and is sent from the base passage 40 to the die (not shown) through the operation output unit 46. Therefore, in the case described above, various unnecessary substances in the molten resin are engaged and captured in the openings 7bb of the mesh 7ba of the mesh body 7b shown in FIG. 4, and countless unnecessary substances 50 are engaged with the openings 7bb. Is done.

In the above-described state, in the related art, each cylindrical screen part 7 is taken out for cleaning or replacement. However, in the present invention, after the operation state of FIG. As shown at the time of washing, when a molten resin for back washing is supplied from the back washing input section 60 provided in the third slide bar 32, the molten resin is supplied to the communication flow path 61 connected to the base flow path 40. Through the guide member 7a and the mesh body 7b to the outside through the discharge groove 44 and the adjustment nozzle 45.

In this case, when the backwashing molten resin passes from the inside to the outside of the opening 7bb of the mesh body 7b, as shown in FIG. As a result, the unnecessary material 50 engaged with the opening 7bb is pushed outward together with the molten resin, so that the mesh 7ba is expanded outward and in the lateral direction, the opening 7bb is enlarged, and the unnecessary material 50 is engaged with the mesh 7ba. Removed from the match. In this case, in order to allow the liquid to pass from the inside to the outside of the cylindrical screen portion 7, the cylindrical mesh body 7b
Thus, the pressure of the molten resin is uniformly applied to all surfaces, all the openings 7bb are widened, and the unnecessary matter 50 is efficiently removed. Accordingly, each cylindrical screen portion 7 is cleaned while being attached to the third slide bar 32, and unnecessary substances are effectively removed. The stop position of the third slide bar 32 is adjusted so that each cylindrical screen portion 7 is not damaged by the pressure difference, so that the difference in the resin inflow amount is reduced. In addition, the adjustment nozzle 45
The pressure difference of the molten resin passing through each cylindrical screen part 7 is adjusted by the adjustment. The above-mentioned molten resin for backwashing is used by backflowing part of the molten resin that has passed through the screen from outside to inside.

[0013]

The method for backwashing a screen according to the present invention comprises:
With the above configuration, the following effects can be obtained. That is, in order to supply the molten resin for backwashing from the inside to the outside of each cylindrical screen part constituting the screen, unnecessary pressure is applied to the outside together with the molten resin by the pressure of the molten resin, and the opening of each mesh is opened. Is expanded so that unnecessary objects can be reliably removed. Therefore, each cylindrical screen portion can be used repeatedly, and the interval of the replacement work can be greatly extended to reduce the running cost. Further, the number of operations required for replacement can be greatly reduced, and the cost of replacement operation can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating a method for backwashing a screen according to the present invention.

FIG. 2 is a sectional configuration diagram of a main part showing an operation state of FIG. 1;

FIG. 3 is a cross-sectional configuration diagram of a main part showing a backwash state of FIG. 1;

FIG. 4 is a configuration diagram showing a state of a mesh body during operation and backwashing of FIG. 1;

FIG. 5 is a configuration diagram showing a conventional screen exchange device.

FIG. 6 is a cross-sectional view showing a cylindrical screen part used in the present invention and a conventional one.

[Explanation of symbols]

 7 Cylindrical screen 7b Mesh body 7bb Opening 50 Unnecessary object

Claims (1)

[Claims] 1. A screen comprising a plurality of cylindrical screen portions (7) for removing unnecessary matter (50) in a molten resin, wherein the plurality of cylindrical screen portions (7) are arranged in an annular shape. The unnecessary material (50) is filtered by passing the molten resin from the inside to the inside, and further, the cylindrical screen portion (7)
The opening (7bb) of the mesh body (7b) of the cylindrical screen portion (7) is expanded by passing the molten resin from the inside to the outside and discharged to the outside to engage with the opening (7bb). A method of backwashing a screen, comprising removing the unnecessary matter (50) from the tubular screen part (7).