JP3625522B2 - Screen changer for plastic extrusion - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a screen changer for plastic extrusion.
[0002]
[Prior art]
When a molten plastic extruder is operated for a long time, foreign matter clogs the screen provided at the pump port, resulting in a decrease in extrusion amount and an increase in back pressure. In this case, stopping the extruder for replacing the screen causes a decrease in production volume and a loss of raw materials. Therefore, a screen changer has been developed and widely used to solve this problem. The most common type of screen changer is the slide method (Fig. 5). Slide the sliding rod P2 with two perforated plates P3 with the screen P4 with a hydraulic cylinder, etc., and replace it with a new perforated plate with a screen. It is something to be made.
[0003]
[Problems to be solved by the invention]
However, when only the screen changer is used, the most common slide method described above will cause a momentary drop in the amount of extrusion, an increase in pressure, and associated discharge fluctuations, no matter how fast the screen is replaced. However, this causes dimensional unevenness in the product (sheet, film, pipe, etc.), and that portion becomes a defect.
[0004]
An object of the present invention is to solve the above-described problems and to provide a screen changer that can reduce discharge fluctuation.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the configuration of the present invention is as follows. In other words, the first configuration includes a casing main body having a rotation rod hole for guiding the column-shaped rotation rod so as to be rotatable about its central axis, and a movable passage that is rotatably inserted into the rotation rod hole. In the outer circumferential surface, two rotating rods in series in the axial direction, a rotating drive shaft coupled to one end of each of the rotating rods, and a porous inserted into the movable passage And a changer inlet main passage and a changer outlet main passage provided in the casing body and spaced around the circumferential direction of the rotating rod hole.
[0006]
In the second configuration, in addition to the first configuration, in the casing main body, the outer surface of the main body extends from the inner surface of the rotary rod hole to a position displaced in the circumferential direction of the rotary rod with respect to the changer inlet main passage. And the rotating rod is provided at a position deviated in the circumferential direction of the rotating rod with respect to the movable passage, and from the inner surface of the movable passage to the outer circumferential surface of the rotating rod. And a movable auxiliary passage to reach.
[0007]
The third configuration includes a valve provided in the discharge passage in addition to the second configuration.
[0008]
In the fourth configuration, in addition to any one of the first to third configurations, the movable passage of the rotating rod penetrates on a straight line passing through the diameter of the rod.
[0009]
In the fifth configuration, in addition to any one of the first to third configurations, the movable passage of the rotating rod penetrates on a curve that changes its direction substantially on the radius of the rod.
[0010]
[Action]
In the operating state, the resin passes through the inlet main passage, the movable passage, the screen, the perforated plate, and the outlet main passage and exits from the pump opening passage by the rotation of the gear. Due to the pressure difference between the inlet main passage and the outlet main passage, a part of the resin passes through the inlet auxiliary passage, three-way switching valve, movable passage, outlet auxiliary passage, and prevents resin stagnation in the screen, perforated plate, and movable passage. doing.
[0011]
If the screen is clogged with foreign matter, move the slide bar to switch the screen. During this movement, the two movable passages open simultaneously in the main passage, so that the resin passes through both of the screens simultaneously. Therefore, the resin passage is not completely blocked.
[0012]
Immediately after the screen is switched, the switching valve switches the flow path. The resin passes through the outlet auxiliary passage due to the pressure difference, passes reversely through the screen, removes foreign matter adhering to the screen surface, and is discharged to the outside through the discharge passage. When the preset cleaning time is over, the switching valve returns to the original flow path, and a small amount of resin always flows through the screen from the inlet auxiliary passage to the outlet auxiliary passage, and the porous plate and the resin in the passage remain. Is prevented from deteriorating.
[0013]
【Example】
Embodiments of the present invention will be described below based on an embodiment shown in the drawings.
In FIGS. 1, 2, and 3, the casing body 10 has a rectangular outer shape when viewed from the front, a rectangular shape when viewed from the side, and a T shape when viewed from the top, and is a steel block formed of a long rectangular column portion 10a and a short rectangular column portion 10b. It is. A cylindrical rotation rod hole 17 for guiding the rotation rod, which will be described later, to rotate in the axial direction thereof, is disposed on the center line in the left-right direction of the long rectangular column portion 10a in parallel with the rotation rod hole. Gear holes 18 (two in the vertical direction) are provided in the short rectangular column portion 10b so as to accommodate a pair of meshing gears.
[0014]
The casing main body 10 has an inlet main passage 11 and an outlet main passage so as to communicate with the rotating rod hole 17 and the gear hole 18 from one outer surface (rear surface) of the casing main body and open to the other outer surface (front surface). 13 and a pump port passage 16 are provided.
[0015]
Two cylindrical rotary rods 2 'and 2' arranged in series in the axial direction in the rotary rod hole 17 are rotatably inserted, and each rotary rod 2 'passes through one movable passage in the diameter direction. 2a '. A perforated plate 3 and a screen 4 are inserted into the movable passage 2a.
[0016]
In FIG. 3, in the casing body 10, the inner surface of the rotating rod hole reaches the outer surface of the main body at a position displaced by approximately 90 degrees in the circumferential direction of the rotating rod 2 ′ with respect to the inlet main passage 11. A discharge passage 19 is provided, and a valve 7 ″ is provided here. 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.
[0017]
2 and 3, a pair of gears 21 and 21 meshing with each other on the outer periphery are rotatably accommodated in the gear hole 18 between the outlet passage 13 and the pump port passage 16. A drive shaft 22 passes through one (upper one) of the gear 21 and the gear hole 18 and is rotatably supported by bearings 23 on both sides of the gear. A driven shaft 24 penetrates the lower part of the gear 21 and is supported rotatably by a bearing 23 in the same manner.
[0018]
A pair of casing first covers 31 are attached to the casing body 10 at both ends of the rotating rod hole 17. The cover 31 also serves as an attachment member for the rotation means 5. A pair of casing second covers 32 are attached to the casing body 10 at both ends of the gear hole 18. A gear drive source (not shown) is coupled to the end of the drive shaft 22 that passes through the second cover 32 on the right side. In FIG. 3, the casing body 10 is provided with a plurality of long through holes parallel to the rotating rod hole 17 and the gear hole 18, and a rod-shaped heater HT is incorporated in them.
[0019]
The operating state will be described below. 2 and 3, the resin passes through the inlet main passage 11, the movable passage 2 a, the screen 4, the perforated plate 3, and the outlet main passage 13, is accommodated in the tooth groove as the gear rotates, and is sent to the pump port. It is sent from the passage 16 to a sheet forming apparatus (not shown). The two movable passages 2a ′ and 2a ′ are always opened in the normal operation state, and the resin flows through both the movable passages 2a ′ and 2a ′. The valve 7 'of the discharge passage is closed.
[0020]
And when either one is clogged like FIG. 4, the rotation rod is rotated 90 degree | times. Thereby, 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. When the valve 7 ′ is opened, a part of the resin that has passed through the movable passage 2a ′ of the one-turn bar flows back through the passage from the outlet passage 13 to eliminate clogging of the screen 4, and the discharge passage. Exit from 2b '.
[0021]
The sliding bar 2 and the rotating bar 2 ′ may be manually rotated. In this case, the cover 31 may not be provided.
[0022]
Next, effects of the embodiment will be described.
As shown in FIGS. 2 and 3, when the resin flows to the gear pump 21 through the screen 4, stable operation can be achieved by the gear pump absorbing the discharge fluctuation when the screen is replaced.
[0023]
When the resin flows from the gear pump 21 to the screen changer in the direction opposite to that in FIG. 3, the rotating rod 2 ′ is rotated 180 degrees. In this case, the pressure increases due to the clogging of the screen, thereby preventing the adverse effect on the extruder side at the gear pump portion at the outlet, and also prevents the reduction of the extrusion amount by the pump action even when the screen is clogged. Further, the molten resin that has exited the gear pump part can eliminate the gear mark by passing through the screen of the screen changer part, the perforated plate, and the resin passage, thereby enabling stable extrusion.
[0024]
In FIG. 5, the movable passage 2a ′ of the rotating rod 2 ′ is provided penetrating on a curve that changes its direction to about 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, the direction is changed by 90 degrees with respect to the pump port passage 16, and the three functions of a screen changer, a gear pump and an elbow are provided. 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 screen 4 side of the movable passage 2a 'communicates with the discharge passage 19' (shown in phantom line). To do. The direction change angle (angle formed by the opening direction of the inlet main passage 11 and the outlet main passage 13) is practically 90 to 160 degrees.
[0025]
As shown in Figs. 3, 4, and 5, 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 part and the gear pump part, the resin traveling direction (straight, up and down, (Left / Right) can be freely selected, and there are many degrees of freedom (upward and downward) due to the extrusion method, installation position, etc.
[0026]
The present invention is also applicable to other liquids than the plastic extrusion.
[0027]
The present invention is not limited to the above-described embodiments and embodiments, but includes various modifications without departing from the spirit and scope of the claims.
[0028]
【The invention's effect】
According to the first configuration of the present invention, even if the operation of the one rotating rod is stopped, the other rotating rod works, so that the molding line can be continuously produced, the production loss can be reduced, and the fluctuation of the outlet flow rate can be reduced.
[0029]
In the second and third configurations, the screen is backwashed in addition to the effects of the first configuration.
[0030]
In the fourth configuration, in addition to the effect of any one of the first to third configurations, the processing of the movable passage is easy.
[0031]
In the fifth configuration, in addition to the effects of any one of the first to third configurations, another component for changing the direction of the flow path can be omitted.
[Brief description of the drawings]
FIG. 1 is a perspective view of an embodiment of the present invention.
2 is a cross-sectional view taken along the line II-II (horizontal) of FIG.
3 is a cross-sectional view taken along the line III-III (vertical) in FIG.
4 is an explanatory diagram of an operation state of FIG. 2;
FIG. 5 is a vertical sectional view of another embodiment.
FIG. 6 is a plan view of a conventional single slide plate type screen changer.
[Explanation of symbols]
2 '... rotating bar 2a' ... movable passage 2b '... movable auxiliary passage 3 ... perforated plate 4 ... screen 5 ... recovery means 7' ... two-way switching valve 10 ... casing body 11 ... inlet main passage 13 ... outlet main passage 16 ... pump port passage 17 ... rotating rod hole 18 ... gear hole 19 ... discharge passage 21 ... gear 22 ... drive shaft 23 ... bearing 31 ... casing first cover 32 ... casing second cover

Claims (5)

A casing body having a rotating rod hole for guiding the cylindrical rotating rod so as to be rotatable around its central axis;
Two rotating rods inserted rotatably in the rotating rod hole, having a movable passage penetrating the outer circumferential surface, and arranged in series in the axial direction;
A rotation drive shaft coupled to one end of each of the rotation rods;
A perforated plate and a screen inserted in the movable passage;
A screen changer for plastic extrusion, comprising a changer inlet main passage and a changer outlet main passage which are provided in the casing body and are spaced around the circumferential direction of the rotating rod hole. In the casing body, a discharge passage extending from the inner surface of the rotating rod hole to the outer surface of the main body at a position displaced in the circumferential direction of the rotating rod with respect to the changer inlet main passage,
A movable auxiliary passage provided at a position deviated in a circumferential direction of the rotary rod with respect to the movable passage and extending from an inner surface of the movable passage to an outer circumferential surface of the rotary rod. The screen changer for plastic extrusion according to claim 1, further comprising: The screen changer for plastic extrusion according to claim 2, further comprising a valve provided in the discharge passage. The screen changer for plastic extrusion according to any one of claims 1 to 3, wherein the movable passage of the rotating rod passes through a straight line passing through the diameter of the rod. The screen changer for plastic extrusion according to any one of claims 1 to 3, wherein the movable passage of the rotating rod passes through a curve that changes direction substantially on the radius of the rod.

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