JPH08300443A - Screen changer for plastic extrusion molding - Google Patents

Abstract

PURPOSE: To make a screen changer less apt to generate clogging by providing a plurality of sets each consisting of a perforated plate and a screen between the inlet and outlet of a molten resin of a movable passage in series and setting the screen on the inlet side rather coarse than the screen on the outlet side. CONSTITUTION: An inlet main passage 11, an outlet main passage 13 and a pump passage 16 are provided to a casing main body. A columnar slide rod 2 is inserted in a slide rod hole 17 in a freely slidable manner and a plurality of movable passages 2a are allowed to pierce the slide rod 2 so as to leave an interval in the length direction of the slide rod 2 and perforated plates 3 and screens 4 are inserted in the movable passages 2a. A plurality of the sets of the perforated plates 3 and the screens 4 are provided between the inlets and outlets of a molten resin of the movable passages 2a on the inlet side in series. The screens on the inlet side are set rather coarse than the screens on the outlet side and the respective screens are held so as to leave an interval through spacers 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a screen changer for extrusion of plastics.

[0002]

2. Description of the Related Art In recent years, the purity of materials for extruded plastic products has been required more and more, and from the viewpoint of resource reuse and reduction of raw material cost, the utilization of scrap or the increase of the mixing rate has been attempted. It is coming. Along with this, there has been a great demand for improving the performance of the screen changer for removing impurities such as dust and unmelted substances in the molten resin. Further, in the conventional screen changer, one set of screen and perforated plate is provided in one flow path.

[0003]

However, clogging occurred relatively early, and it was often necessary to replace the screen.

An object of the present invention is to solve the above problems and to provide a screen changer which is less likely to cause clogging.

[0005]

In order to solve the above problems, the structure of the present invention is as follows. That is, the first configuration is a casing main body having a slide rod hole for guiding the slide rod so that the slide rod can slide in the longitudinal direction, and a slidable insertion into the slide rod hole so that a plurality of movable passages are connected to each other. A sliding rod having a space in the length direction, a set of a perforated plate and a screen inserted into the movable passage, and provided on the casing body,
In the one including an inlet main passage and an outlet main passage that are spaced around the sliding rod hole, the set of the perforated plate and the screen is arranged in series between the inlet and the outlet of the molten resin of the movable passage. A plurality of sets are provided, and the screen on the inlet side is coarser than the screen on the outlet side.

In the second structure, a casing main body having a rotating rod hole for guiding the cylindrical rotating rod so as to be rotatable about its central axis, and a casing body which is rotatably inserted into the rotating rod hole and is movable. Two rotary rods having passages penetrating the outer circumferential surface thereof and arranged in series or in parallel in the axial direction, a rotary drive shaft coupled to one end of each of the rotary rods, and inserted into the movable passage. A perforated plate and a screen that are provided in the casing body, are spaced around the circumference of the pivot rod hole, and include an inlet main passage and an outlet main passage, the combination of the perforated plate and the screen. That is, a plurality of sets are provided in series between the inlet and the outlet of the molten resin in the movable passage, and the screen on the inlet side is coarser than the screen on the outlet side.

In the third structure, in addition to the first or second structure, the pair of the perforated plate and the screen is provided on the inlet side of the movable passage, and the screens are kept spaced apart from each other. It is that you are.

In the fourth structure, in addition to the first or second structure, one or more sets of the perforated plate and the screen are provided on the inlet side of the movable passage and one or more sets on the outlet side. . The fifth structure is that in addition to any one of the first to fourth structures, the movable passage of the sliding rod or the rotating rod penetrates on a straight line passing through substantially the diameter of the rod.

In the sixth structure, in addition to any one of the first to fourth structures, the movable passage of the sliding rod or the rotating rod penetrates on a curve that changes the direction substantially on the radius of the rod. That is.

[0010]

In the operating state, the resin goes out through the inlet main passage, the movable passage, the screen, the perforated plate, and the outlet main passage. Large foreign matter is captured on the coarse screen and small foreign matter is captured on the fine screen. If the screen is clogged with foreign matter, slide the sliding rod to switch the screen or rotate the clogged rotating rod to backwash.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below based on an embodiment shown in the drawings. 1, 2, and 3, the casing main body 10 has an outer shape that is rectangular in a front view, rectangular in a side view, and T-shaped in a plan view, and has a long rectangular column portion 10 a and a short rectangular column portion 10.
It is a block of steel consisting of b. A cylindrical sliding rod hole 17 for guiding the sliding rod 2 to be described later so as to slide in the longitudinal direction is formed on the center line of the elongated rectangular column 10a in the left-right direction in parallel with the sliding rod hole. The gear holes 18 (two at the top and bottom) are housed in the short rectangular column 10 to accommodate a pair of meshing gears.
b respectively.

The casing main body 10 is provided with an inlet main passage 11, so that the sliding rod hole 17 and the gear hole 18 are communicated from one outer surface (rear surface) of the casing body to the other outer surface (front surface). An outlet main passage 13 and a pump inlet passage 16 are provided.

A plurality of cylindrical sliding rods 2 are slidably inserted into the sliding rod holes 17 and are diametrically penetrated (two in the figure).
The movable passages 2a are held at intervals in the rod length direction. The perforated plate 3 and the screen 4 are inserted into the movable passage 2a. As for the set of the porous plate 3 and the screen 4, a plurality of sets (two sets in the drawing) are provided in series on the inlet side between the inlet and the outlet of the molten resin of the movable passage 2a. The screen on the inlet side is set to be coarser than the screen on the outlet side, and the screens are kept spaced apart from each other via a spacer 8. A pair of gears 21 and 21 meshing with each other on the outer circumference is provided. In the gear hole 18, the outlet passage 13 and the pump inlet passage 1
6 and 6 are rotatably accommodated. A drive shaft 22 penetrates one (upper) of the gear 21 and penetrates the gear hole 18, and is rotatably supported by bearings 23 on both sides of the gear. A driven shaft 24 penetrates under the gear 21, and is similarly rotatably supported by a bearing 23.

A pair of casing first covers 31 are attached to the casing body 10 at both ends of the sliding rod hole 17. The cover 31 on the right side also serves as a mounting member for the hydraulic piston cylinder mechanism serving as the reciprocating means 5. A pair of casing second covers 32 is attached to the casing body 10 at both ends of the gear hole 18. Right side second cover 32
A gear drive source (not shown) is coupled to the end of the drive shaft 22 that penetrates through the casing body 10 in FIG.
A plurality of long through holes are provided in parallel with the gear hole 18, and the rod-shaped heater HT is built therein.

Now, the interval between the adjacent movable passages 2a of the sliding rod 2 is determined so that the other movable passage 2a is opened before the one movable passage 2a is closed.

In the casing main body 10, an auxiliary inlet from the main inlet passage 11 to the inner surface of the sliding rod hole 17 of the main body 10 on both sides of the main inlet passage 11 in the sliding direction of the sliding rod 2. A passage 12 is provided. Similarly, a groove-shaped outlet auxiliary passage extending from the outlet main passage 13 along the inner surface of the sliding rod hole 17 of the main body 10 on both sides of the outlet main passage 13 in the sliding direction of the sliding rod 2. 14 is provided.

Further, a discharge passage 15 extending from the auxiliary inlet passage 12 to the outer surface of the main body 10 is provided, and a three-way switching valve (or cock) is provided at a connection point between these passages 12, 15.
6 are provided.

The operation state will be described above. In the operating state of FIG. 2, the resin is the main inlet passage 11 and the movable passage 2
a, the screen 4, the perforated plate 3 and the outlet main passage 13, are accommodated in the tooth groove as the gear rotates, and are fed, and are fed from the pump inlet passage 16 to a sheet forming apparatus (not shown). Then, a large foreign matter is captured on the coarse screen and a small foreign matter is captured on the fine screen. Therefore, the area of the screen is increased and abrupt pressure rise is prevented.

Here, the inlet main passage 11 and the outlet main passage 13
Part of the resin (bypass flow) due to the pressure difference in the part of the right side, the auxiliary inlet passage 12 on the right side, the three-way switching valve 6, the movable passage 2
a, passing through the outlet auxiliary passage 14 and passing through the right side screen 4,
Resin retention in the perforated plate 3 and the movable passage 2a is prevented. The left auxiliary passage 12 is closed near the left end of the sliding rod 2, the switching valve 6 cuts off the discharge passage 15, and the resin therein does not flow.

When the screen 4 is clogged with foreign matter, the reciprocating means 5 moves the sliding rod 2 to the position shown in FIG. During this movement (FIG. 4), the two movable passages 2a simultaneously open in the main passage 11 and the outlet main passage 13, so that the resin passes through both the screens 4 at the same time. Therefore, the resin passage is not completely closed.

Immediately after the screen 4 is switched to the position shown in FIG. 5, the inlet auxiliary passage 12 shown in FIG. 6 is closed and the discharge passage 15 is opened to a switching valve 6 by an external drive source (not shown). Switches the flow path. The resin passes through the outlet auxiliary passage 14 on the left side due to the pressure difference, passes through the screen 4 in the opposite direction, removes foreign matters adhering to the surface of the screen on the left side, and is discharged outside by the discharge passage 15 on the left side.

After a preset washing time, the switching valve 6 returns to the state shown in FIG. 5, and a small amount of resin always passes through the screen 4 from the left auxiliary inlet passage 12 to the auxiliary outlet passage 14. The flow prevents the resin in the left side porous plate 3 and the passage from being deteriorated due to retention.

FIG. 7 shows another embodiment. Since there is no inlet auxiliary passage, there is no bypass flow of resin, and the resin is simply flowed back to the screen 4 and discharged. That is, in the casing body 10, the discharge passages 15 extending from the inner surface of the slide rod hole 17 of the body 1 to the outer surface of the body are provided on both sides of the inlet main passage 11 in the sliding direction of the slide rod 2. To be From the outlet main passage 13 to the main body 1 on both sides in the sliding direction of the sliding rod 2 with respect to the outlet main passage 13.
An outlet auxiliary passage 14 reaching the inner surface of the sliding rod hole of 0 is provided. A two-way switching valve (or cock) 7 is provided in the discharge passage 15 or the outlet auxiliary passage 14. In the state of FIG. 7, a part of the resin flows back and is discharged to the outside from the outlet auxiliary passage 14 and the discharge passage 15, and the screen 4 is backwashed. When the flow path of the two-way switching valve 7 is switched, the flow in the passages 14 and 15 is stopped.

FIG. 8 shows still another embodiment. That is, the outlet auxiliary passage 14 may be provided so as to penetrate the inside of the casing body 10, or the movable passages 2 a, 2 of the sliding rod 2 may be provided.
A hole or groove (indicated by a dotted line) that communicates between a is provided.

When two sets of the sliding rods 2 are provided in parallel, the movable passages of either set are always the main passages 11, 1.
Connect to 3. Therefore, the distance between the adjacent movable passages 2a of the sliding rod 2 does not need to be determined so that the other movable passage 2a is opened before the one movable passage 2a is closed, and even if the distance is wider than that. Good.

9 and 10 show another embodiment, in which the sliding rod 2 is replaced by a rotating rod 2 '. That is, a cylindrical rotating rod hole 17 for guiding the rotating rod to be described later so as to be rotatable in its axial direction is provided in the elongated rectangular column portion 10a. Two cylindrical rotating rods 2 ', 2', which are axially connected in series, are rotatably inserted in the rotating rod hole 17, and each rotating rod 2'is one movable passage penetrating in the diametrical direction. It has 2a '.

In the casing body 10, with respect to the inlet main passage 11, there is approximately 9 in the circumferential direction of the rotating rod 2 '.
A discharge passage 19 extending from the inner surface of the rotating rod hole to the outer surface of the main body is provided at a position offset by 0 degree. Further, in the rotating rod 2 ', a movable auxiliary passage 2b' extending from the inner surface of the movable passage 2a 'to the outer peripheral surface of the rotating rod 2'is provided.

The operating state will be described below. In FIGS. 9 and 10, the two movable passages 2a 'and 2a' are always opened in the normal operation state, and the resin flows through both movable passages 2a 'and 2a'. The valve 7'in the discharge passage is closed. Then, when one of them causes clogging, the rotation bar is rotated 90 degrees as shown in FIG. As a result, the inlet main passage 11 and the movable passage 2a 'are blocked, and the outlet main passage 13, the auxiliary movable passage 19, the movable passage 2a', the perforated plate 3, the screen 4 and the discharge passage 2b 'communicate with each other. Then, when the valve 7'is opened, a part of the resin that has passed through the movable passage 2a 'of the one-side turning rod flows back through the passages from the outlet passage 13 to clear the clogging of the screen 4 and to discharge the discharge passage Exit from 2b '.

The sliding rod 2 and the rotating rod 2'may be manually rotated, and in this case, the cover 31 may not be provided.

In the embodiment of FIG. 24, one or more sets of the perforated plate 3 and the screen 4 are provided on the inlet side of the movable passages 2a, 2a 'and one or more sets on the outlet side. In this case, in addition to the above effects, the inlet pressure P1 and the outlet pressure P2 cancel each other out, so that the force for pressing the sliding rod 2 and the rotating rod 2'to the casing 10 becomes weak, and the force required to move these rods. Is less.

As shown in FIGS. 16 and 17, the casing body 10 includes a long rectangular column portion 10a having a sliding rod and a rotating rod,
The short rectangular column portion 10b having the gear is separated from the flange portion 10c and the bolt B protruding from both or one side.
They may be combined with each other to form a block, and this form is also included in the present invention.

Next, another effect of the above embodiment will be described. This device combines the excellent functions of the screen changer and the gear pump, and has the feature of complementing the drawbacks of the single use. In addition, the entire structure is compact and has a large energy saving effect, and the extrusion direction and function order can be easily changed by only changing some parts without using any other means for the extrusion molding method or space relations. It is a high equipment.

If the movable passages 2a and 2a 'penetrate straightly, the machining is easy, and if they penetrate the curved passage, a separate component for changing the direction of the flow path can be omitted.

As shown in FIGS. 3 and 10, the screen 4
When the resin flows to the gear pump 21 through the gear pump 21, the gear pump absorbs the fluctuation in the discharge when the screen is replaced, so that stable operation can be performed.

In the opposite direction of FIGS. 3 and 10, the gear pump 21
If the resin flows from the screen changer to the screen changer, the pressure increase due to the screen clogging, which adversely affects the extruder side, is prevented by the gear pump section at the outlet, and even when the screen is clogged the pump action Prevents a decrease in extrusion rate. Further, the molten resin discharged from the gear pump portion can eliminate the gear mark by passing through the screen of the screen changer portion, the perforated plate, and the resin passage, and stable extrusion can be performed. In this case, in the sliding rod type as shown in FIG. 21, the inlet passage serves as the outlet passage 13 and the outlet passage serves as the inlet passage 11. Accordingly, the auxiliary passages 12 and 14 and the discharge passage 15 have an inverse relationship to the above. In the case of the rotating rod type, in FIG. 10, the rotating rod 2'is rotated by 180 degrees.

FIG. 14 shows an arrangement of a commonly used extruder EX--screen changer SC--connection passage JC--gear pump GP, and FIG. 15 shows an extruder EX--breaker plate BP--gear pump GP--screen. The sequence of changer SC is shown. As can be seen from these and FIGS. 3 and 10, considerable space saving can be achieved.

The screen changer S shown in FIG.
In comparison between the heater (not shown) provided around C, the connection passage JC and the gear pump GP and the heater HT in FIG. 3, energy saving of about 40% can be achieved.

It is clear from the comparison between FIGS. 14 and 3 that the shortening of the resin passage is shortened, and by this, the residence time of the resin can be shortened, so that the deterioration of the resin and thus the product can be prevented.
Further, since the pressure rise is small, there is no adverse effect on the extruder (for example, vent up, thrust pressure rise). Here, the term "vent up" means that the resin flows backward due to a rise in the tip pressure at the gas outlet at the exit of the extruder cylinder and overflows from the gas outlet.

FIG. 12 shows that the movable passages 2a, 2a 'of the sliding rod 2 or the rotating rod 2'are provided so as to penetrate through a curve that turns around 90 degrees on the radius of the rod. . In this case, the inlet main passage 11 is provided on the upper surface of the casing body 10, and the direction of the pump main passage 16 is changed by 90 degrees, and it has three functions of a screen changer, a gear pump and an elbow. In the case of the rotating rod 2 ′, the movable auxiliary passage 2b ′ is provided outside the bent portion (shown in phantom), and when the passage 2b ′ communicates with the outlet passage 13, the movable passage 2a ′ is provided.
The screen 4 side of is communicated with the discharge passage 19 '(shown in phantom). In addition, the turning angle as described above (the entrance main passage 11
And the angle between the outlet main passage 13 and the opening direction) is 90 to 16
0 degree is practical.

As shown in FIGS. 3, 10, 11, and 12, by replacing some parts, changing the rotation direction, and changing the position of the inlet / outlet hole, the front / rear relationship between the screen changer portion and the gear pump portion, the advancing direction of the resin ( (Straight, up / down, left / right)
Can be freely selected, and there are many degrees of freedom (upward and downward) due to the extrusion molding method and installation position.

Now, a case where the present invention is applied to an upward blow film forming apparatus will be described. FIG. 19 is a vertical sectional view of a conventional upward blow film forming apparatus. A film F is formed into a balloon shape from the die lip DL through the extruder EX, the screen changer SC, the vertical elbow EL, and the die DE, is drawn into a sheet by the take-up roll ER, and is wound up by the winder W. However, the difference in the flow velocity of the molten resin inside the elbow portion EL and the difference in the passage time due to the difference in the passage length expand in the circumferential direction at the die lip portion DL, and the thickness difference and the quality difference when the film is formed. Will appear.

FIG. 18 shows an example in which the apparatus of the present invention in which the direction of the flow path is changed by 90 degrees as shown in FIG. 12 is applied to a blow film molding apparatus. Extruder EX for sending molten resin horizontally
And the die DE that pushes the film from bottom to top,
The device of the present invention is connected. The device of the present invention is in a state where the sliding rod 2 or the rotating rod 2 ′ is on the lower side and the gears 21 and 21 are on the upper side, and the inlet main passage 11 is opened on the lower side surface and the pump inlet passage 16 is opened on the upper surface. . The direction of the resin flow is changed in the same space as the screen changer SC and the elbow EL of FIG. 19, and the functions of the screen changer and the gear pump are exhibited at the same time. It is possible to absorb the adverse effect of uneven flow in the elbow portion EL in FIG. 19 in the gear pump 21. Further, the high pressure generated in the die DE is received by the gear pump, and an excessive load is not applied to the extruder EX part.

FIG. 20 shows an embodiment in which a gear hole 18 is provided in the sliding body hole (rotating bar hole) 17 of the casing main body 10 so as to intersect with each other at right angles.

In FIG. 2, if another set of gear pumps is integrated with the resin inlet of the screen changer, the pressure of the resin is boosted by two sets of gear pumps, so high-pressure and high-precision resin molding is possible. Become. Further, in FIG. 21, another set of the second screen changer unit is integrated with the resin inlet of the gear pump unit, and when the screen of the second screen changer is coarse and the first screen is fine, molding with a large amount of resin is achieved. There is a winning effect.

22 and 23 show still another embodiment, in which a groove or hole communicating between the movable passages 2a, 2a of the sliding rod 2 is provided as the inlet auxiliary passage 12, and a two-way switching valve (or cock) is provided. 7 is provided in the discharge passage 15.

In FIG. 22, the main flow Q of resin flows through the inlet main passage 11, the left movable passage 2a, and the outlet main passage 13.
The minute flow (bypass) ΔQ flows through the inlet auxiliary passage 12, the right movable passage 2a, and the outlet auxiliary passage 14 to prevent stagnant flow in the right movable passage 2a.

In FIG. 23, when the screen 4 is clogged, the sliding rod 2 is moved to the left and the left valve 7 is opened. The main stream Q passes through the movable passage 2a on the right, and exits the main passage 1
Go out of 3. At the same time, the minute flow ΔQ from the right movable passage 2a flows backward through the outlet auxiliary passage 14 and the left movable passage 2a due to the pressure difference, and the clogging of the screen 4 is discharged from the valve 7 through the discharge passage 15 and washed. . At that time, the minute flow ΔQ from the inlet auxiliary passage 12 is also discharged at the same time, but since this is extremely small with respect to the main flow Q, the performance is not affected. When the cleaning is completed and the valve 7 is closed, the minute flow from the inlet auxiliary passage 12 prevents the stagnant flow in the left movable passage 2a, as described above.

When the right screen 4 is clogged, the sliding rod 2 is moved to the right again to the state shown in FIG. 22, the valve 7 is opened and the washing is performed in the same manner as described above, and then the valve 7 is closed. A minute flow ΔQ is secured in the right movable passage 2a.

The present invention is applicable to other liquids than the above plastic extrusion.

The present invention is not limited to the above-described examples and embodiments, but includes various modifications without departing from the spirit and scope of the claims.

[0051]

According to the first configuration of the present invention, large foreign matter is captured on the coarse screen and small foreign matter is captured on the fine screen. For this reason, the time until the clogging is significantly increased. In addition, the screen area is increased, and a sudden pressure increase is prevented.

The second structure exhibits the same effect as the first structure. In addition, there is little fluctuation in the flow rate when the screen is replaced.

With the third structure, the same effects as those of the first or second structure are exhibited.

In addition to the effects of the first or second structure, the fourth structure offsets the inlet pressure and the outlet pressure of the movable flow path, so that the force for pressing the sliding rod and the rotating rod against the casing becomes weak. , It requires less force to move these rods.

According to the fifth structure, in addition to the effect of any one of the first to fourth structures, it is easy to process the movable passage.

According to the sixth structure, in addition to the effect of any one of the first to fourth structures, a separate component for changing the direction of the flow path can be omitted.

[0057]

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment (sliding rod type) of the present invention.

[0058]

FIG. 2 is a sectional view taken along line II-II (horizontal) of FIG.

[0059]

3 is a III-III (vertical) sectional view of FIG.

[0060]

FIG. 4 is an explanatory diagram of an operating state of FIG.

[0061]

5 is an explanatory diagram of an operating state of FIG. 2. FIG.

[0062]

FIG. 6 is an explanatory diagram of an operating state of FIG.

[0063]

FIG. 7 is a vertical sectional view of another embodiment of the present invention.

[0064]

FIG. 8 is a vertical sectional view of another embodiment of the present invention.

[0065]

FIG. 9 is a horizontal sectional view of another embodiment (rotating rod type) of the present invention.

[0066]

10 is a cross-sectional view taken along line XX of FIG. 9.

[0067]

11 is an explanatory view of the operating state of FIG.

[0068]

FIG. 12 is a diagram of another embodiment of FIGS.

[0069]

FIG. 13 is a plan view of a conventional single slide plate type screen exchange device.

[0070]

FIG. 14 is a first example view of a conventional arrangement of a changer and a gear pump.

[0071]

FIG. 15 is a second example view of the arrangement of the conventional changer and the gear pump.

[0072]

FIG. 16 is an embodiment diagram in which the casing main body is divided into two parts, and the casing main body is connected by facing flanges.

[0073]

FIG. 17 is an embodiment diagram in which the casing main body is divided into two and is joined by one flange.

[0074]

FIG. 18 is a vertical cross-sectional view of an example in which the device of the present invention having a direction changing flow path is applied to an upward blow film molding device.

[0075]

FIG. 19 is a vertical cross-sectional view of an example of a conventional upward blow film molding apparatus.

[0076]

FIG. 20 is a vertical cross-sectional view of an embodiment in which a sliding rod hole and a gear hole are orthogonal to each other in a streak.

[0077]

FIG. 21 is the entrance of the screen changer in FIG.
In this embodiment, the outlet is reversed.

[0078]

FIG. 22 is a horizontal sectional view of another embodiment (sliding rod type) of the present invention.

[0079]

FIG. 23 is an explanatory diagram of an operating state of FIG. 22.

[0080]

FIG. 24 is a vertical cross-sectional view of another embodiment (screen position) of the present invention.

[0081]

[Explanation of symbols]

 2 ... Sliding bar 2a ... Movable passage 3 ... Perforated plate 4 ... Screen 5 ... Reciprocating means 6 ... 3-way switching valve 7 ... 2-way switching valve 8 ... Spacer 10 ... Casing body 11 ... Inlet main passage 12 ... Inlet auxiliary passage 13 Outlet main passage 14 Outlet auxiliary passage 15 Discharge passage 16 Pump outlet passage 17 Sliding rod hole 18 Gear hole 21 Gear wheel 22 Drive shaft 23 Bearings 31 Casing first cover 32 Casing second cover

Claims (6)

[Claims] 1. A casing main body having a slide rod hole for guiding the slide rod so that the slide rod can slide in the longitudinal direction, and a plurality of movable passages that are slidably inserted into the slide rod hole. A slide rod having a space in the direction, a set of a perforated plate and a screen inserted into the movable passage, and an inlet main passage provided in the casing body and spaced around the slide rod hole. And an outlet main passage, the set of the perforated plate and the screen, a plurality of sets are provided in series between the inlet and the outlet of the molten resin of the movable passage,
A screen changer for plastic extrusion molding, characterized in that the screen on the inlet side is coarser than the screen on the outlet side. 2. A casing body having a rotating rod hole for guiding a cylindrical rotating rod so as to be rotatable about its central axis, and a casing body which is rotatably inserted into the rotating rod hole and which is outside the movable passage. Two rotating rods penetrating the circumferential surface and connected in series or in parallel in the axial direction, a rotating drive shaft connected to one end of each of the rotating rods, and a multi-hole inserted in the movable passage. A plate and a screen, which are provided in the casing body, are spaced around the circumference of the pivot rod hole, and include an inlet main passage and an outlet main passage, wherein the combination of the perforated plate and the screen is A plurality of sets are provided in series between the inlet and the outlet of the molten resin of the movable passage,
A screen changer for plastic extrusion molding, characterized in that the screen on the inlet side is coarser than the screen on the outlet side. 3. The combination of the perforated plate and the screen is provided on the inlet side of the movable passage, and the screens are kept spaced apart from each other. A screen changer for the described plastic extrusion. 4. The plastic extrusion according to claim 1, wherein at least one set of the perforated plate and the screen is provided at an inlet side of the movable passage and at least one set is provided at an outlet side of the movable passage. Screen changer for molding. 5. The movable passage of the sliding rod or the rotating rod is
The screen changer for plastic extrusion molding according to any one of claims 1 to 4, wherein the screen changer penetrates on a straight line that passes through substantially the diameter of the rod. 6. The movable passage of the sliding rod or the rotating rod,
A screen changer for plastic extrusion according to any one of claims 1 to 4, wherein the screen changer penetrates on a curve that changes the direction of the rod substantially on a radius.