JP6868413B2 - Screen changer and extruder and hollow molding machine using it - Google Patents

Description

The present invention relates to a screen changer that is disposed in a flow path of a fluid such as a molten thermoplastic resin and removes foreign substances in the fluid, and an extruder and a hollow molding machine using the screen changer.

The extruder used for molding a thermoplastic resin molded product includes a heating cylinder and a screw provided in the heating cylinder so as to be rotatable. A head that gives a shape to the extruded molten resin is attached to the tip of the heating cylinder, and a screen changer equipped with a screen for capturing and removing foreign substances in the molten resin is provided on the upstream side of the head. It is provided. As a representative of such a screen changer, for example, the one disclosed in Patent Document 1 is known.

The screen mounting structure for an extruder disclosed in Patent Document 1 includes a pressurizing ring that presses the screen against an external ring and an adjusting ring that adjusts the pressing force of the pressurizing ring. The contact surface between the pressure ring and the adjusting ring is provided with a fitting portion formed of a concave portion and a convex portion for preventing leakage of the molten resin. However, since the contact surface between the pressure ring and the adjustment ring on which the uneven fitting portion is formed is only pressed by the mechanical external force of the screw, the resin becomes resin when the pressure of the molten resin increases. Leakage may occur.

Therefore, in order to prevent the resin leakage as described above, Patent Document 2 discloses a screen changer in which a plurality of O-rings are used in combination as a sealing member. In the structure of the screen changer disclosed in Patent Document 2, a plurality of O-rings are used in combination as a sealing member, and then each of the first ring body, the second ring body, and the breaker plate holding the screen is used. The boss screwed in from the downstream side in the flow direction of the molten resin is used for pressure contact.

Further, a screen changer disclosed in Patent Document 3 has been proposed as a screen changer focusing on the speed of replacement work of a filter having a screen. In the screen changer disclosed in Patent Document 3, a plurality of filters are prepared in advance in the filter carrier assembly that can slide in the direction across the polymer flow passage, and the filters can be replaced by sliding the filter carrier assembly. It is designed to be done quickly. A polymer seal is used to seal the polymer flow passage and the filter.

Japanese Unexamined Patent Publication No. 8-11191 Japanese Patent No. 3945781 Special Table 2001-520131

However, in the structure disclosed in Patent Document 2, even if resin leakage can be suppressed by using a plurality of O-rings in combination, each O-ring is always subjected to the pressure and heat of the molten resin. There is a concern that the durability will decrease due to sagging.

This also applies to the structure disclosed in Patent Document 3, in which a polymer seal is used to seal the polymer flow passage and the filter. Further, particularly in the polymer seal disclosed in Patent Document 3, since an annular recess is formed on the upstream side in the polymer flow direction of the seal itself, the molten polymer (molten resin) stays in the annular recess. , There was a risk of burning the molten resin. If the molten resin that has been burnt is mixed in the molded product, the appearance of the molded product may be poor, which is not preferable.

Therefore, in order to improve the durability of the sealing member that controls the seal and prevent the molten resin from burning, it is desirable to adopt a seal structure that does not use an O-ring or a polymer seal.

The present invention has been made in view of such a problem, and similarly to the one disclosed in Patent Document 3, it is provided with at least two porous breaker plates provided with a screen, and the breaker plates are provided. We provide a screen changer that can prevent leakage of the pumping fluid without using an O-ring or polymer seal, and can prevent secondary problems such as burning of the pumping fluid, while ensuring the speed of replacement work. Is what you do. Further, the present invention provides an extruder and a hollow molding machine using the screen changer.

According to the present invention, a screen block on which a fluid pressure feeding flow path is formed, a slide plate slidably mounted in a direction crossing the fluid pressure feeding flow path of the screen block, and a slide plate detachably supported by the slide plate. Along with, at least two porous breaker plates provided with a screen are provided, and the slide operation of the slide plate causes the breaker plate supported by the slide plate to be positioned in the fluid pumping flow path of the screen block. It is a screen changer that is designed to let you.

On top of that, a pressure ring forming the fluid pressure feeding passage is provided facing the side surface on the upstream side of the slide plate, and a seal ring capable of increasing the diameter is provided adjacent to the upstream side of the pressure ring. A pressure receiving ring is provided so as to face the downstream side surface of the slide plate and form the fluid pressure feeding passage. The seal ring is characterized in that the pressure ring is brought into pressure contact with the slide plate by expanding the diameter in response to the pressure of the fluid flowing in the fluid pressure feeding flow path. ..

The screen changer according to the present invention is mainly provided at the tip of a heating cylinder in an extruder, but its application is not limited to the extruder. For example, in various production facilities, manufacturing plants, etc., it is possible to interpose in a pumping path for pumping a relatively viscous fluid.

The function of the seal ring is to form a part of the fluid pressure feed flow path, expand the diameter by receiving the pressure of the fluid flowing in the fluid pressure feed flow path, and attach a pressure ring adjacent to the pressure ring to the slide plate. It is a pressure contact. As a more specific embodiment, the seal ring is divided into a plurality of ring pieces in the circumferential direction, and each ring piece slides to expand the diameter, and pressurizes the seal ring with the seal ring. It is desirable that the ring is in contact with the tapered surface.

Such a seal ring composed of a plurality of ring pieces can smooth the movement of each ring piece in the outer peripheral direction due to the pressure of the fluid to be pumped, make the sealing force uniform in the ring circumferential direction, and enhance the sealing force. Is. The number of ring pieces forming the seal ring is not particularly limited as long as the function of the seal ring described above can be achieved. The larger the number of ring pieces, the more preferable, but from the viewpoint of manufacturing, for example, about 4 to 8 is desirable.

The pressure receiving portion may be provided as a separate pressure receiving ring, for example, or a part of the screen block may function as the pressure receiving portion.

Further, the screen block may be an integral type as long as it has a structure capable of slidably supporting the slide plate, but when considering the assembling property with other related members, the screen blocks are individually provided. It is desirable that an upstream block and a downstream block in which a fluid pumping flow path is formed are provided, and a slide plate is arranged between the upstream block and the downstream block.

The slide type of the slide plate may be a linear motion type as described in Patent Document 3, but as a form in consideration of space efficiency, the slide plate swings in a direction crossing the fluid pumping flow path of the screen block. It is desirable that it is a so-called swing type that slides while sliding.

Therefore, in the present invention, the diameter of the seal ring is expanded by receiving the pressure of the fluid to be pumped, and the pressure ring is pressed against the slide plate by the force of the diameter expansion, so that the two are in pressure contact with each other. As a result, the sealing property of the breaker plate located in the fluid pressure feed flow path is ensured. In this case, the pressure receiving portion backs up the slide plate to which the pressure ring is pressed.

According to the present invention, the sealing property of the breaker plate located in the fluid pumping flow path can be ensured without using a sealing member such as an O-ring, leakage of the pumping fluid can be prevented, and the pumping fluid can be prevented from leaking. No problems such as scorching occur.

A side view showing an example of an extruder to which the screen changer is applied as a first embodiment of the screen changer according to the present invention. An enlarged perspective view of the screen changer shown in FIG. An exploded perspective view of a main part of the screen changer shown in FIG. Explanatory drawing which shows the movement of the screen changer shown in FIG. An explanatory view showing the movement of the screen changer also shown in FIG. FIG. 2 is a vertical cross-sectional view of the screen changer shown in FIG. An enlarged view of a main part of FIG. FIG. 7 is a perspective view of the seal ring shown in FIG. FIG. 3 is a perspective view of one ring piece forming the seal ring shown in FIG. The functional explanatory view of the seal ring shown in FIG. The functional explanatory view of the seal ring shown in FIG. It is a figure which shows the 2nd Embodiment of the screen changer which concerns on this invention, and is the vertical sectional view of the part equivalent to FIG. It is a figure which shows the 3rd Embodiment of the screen changer which concerns on this invention, and is the vertical sectional view of the part equivalent to FIG. An enlarged view of a main part of FIG. FIG. 5 is a side view of the hollow molding machine provided with the extruder of FIG.

1 to 11 show a first embodiment for carrying out the screen changer according to the present invention, and FIG. 1 particularly shows an example of an extruder for a hollow molding machine (blow molding machine) to which the screen changer according to the present invention is applied. The outline is shown as.

The extruder 1 shown in FIG. 1 is installed on a gantry of a molding machine (not shown), and has a hopper 2, a screw 3, a heating cylinder (barrel) 4 containing the screw 3, and the like. A screen changer 5 is provided at the tip of the heating cylinder 4. As is well known, the screw 3 is composed of a feed unit, a compression unit, and a measuring unit in this order from the hopper 2 side where the base end is located to the tip end.

The feed portion is a boundary area in which resin pellets supplied from the hopper 2 of the extruder 1, that is, solid resin is transported while being heated toward the tip of the screw 3, and has an equal pitch interval from the base end to the tip of the screw 3. It is equipped with a main flight arranged in a spiral shape. The groove depth of the feed portion is constant, and is always set to be larger than that of the compression portion and the measuring portion.

The compression section is a region that promotes the melting of the resin by pressurizing and compressing the resin that has been preheated in the feed section and partially melted and supplies mechanical energy, and is composed of a main flight that continues from the feed section. A subflight that crosses the main flight diagonally is provided in the screw groove to form a melting promoting portion of the molten resin.

The measuring unit is a region that promotes homogenization of the resin that has been almost completely melted in the compression unit and rectifies it. Has a subfreight in.

Therefore, in the extruder 1 shown in FIG. 1, the resin pellets supplied from the hopper 2, that is, the solid resin, is transferred from the feed portion of the screw 3 to the compression portion, and is heated from the heating cylinder 4 and sheared heat generated by the heating cylinder 4. However, it is separated into a molten resin part and a solid-state resin part by the subflight of the compression part, and shear heat generation works effectively in the solid-state resin part to improve the melting ability, stabilize the melting, and melt. Is also promoted.

The molten resin pumped from the compression section to the measuring section is further disturbed and mixed in the measuring section, and is swept away in a homogeneous state as a whole and pumped to the screen changer 5. In the screen changer 5, foreign matter in the molten resin is captured and removed and pumped to the downstream side. The detailed structure and function of the screen changer 5 will be described later.

2 is an enlarged perspective view of the screen changer 5 shown in FIG. 1, FIG. 3 is an exploded perspective view of a main part of the screen changer 5 shown in FIG. 2, and FIGS. 4 and 5 are screens shown in FIG. The movements of the changer 5 are shown respectively. Further, FIG. 6 shows a vertical cross-sectional view of the screen changer 5 shown in FIG.

As shown in FIG. 2, the screen changer 5 can be freely inserted into and removed from the screen block 6 having a resin passage 10 (see FIG. 6) that serves as a passage for molten resin as a fluid pumping flow path. It is composed of a mounted slide plate 9.

As shown in FIG. 1, the screen block 6 is attached to the tip of the heating cylinder 4 in the screw type extruder 1, and is upstream in which a resin passage 10 through which the pumped molten resin flows is formed in the axial direction. It includes a side block 7 and a downstream block 8. As shown in FIGS. 1 and 6, these upstream block 7 and downstream block 8 are formed by a plurality of (three in this case) bolts 11a and 11b and collars 12 inserted into the respective bolts 11a and 11b. The distance between the two is fixed to each other in a manner regulated by the collar 12.

Further, a slide plate 9 is arranged between the upstream block 7 and the downstream block 8, and one of the plurality of bolts 11a and 11b and the collar 12 inserted therein are the slide plate 9. Is rotatably and removablely supported. That is, the slide plate 9 arranged so as to be sandwiched between the upstream block 7 and the downstream block 8 is formed as a so-called swivel or swing type that can swing around one bolt 11a as the center of rotation. Has been done.

Here, as shown in FIG. 6, the portion of the resin passage 10 on the upstream side block 7 side of the slide plate 9 with the slide plate 9 sandwiched therein is referred to as an upstream side passage 10a. On the other hand, on the downstream side of the slide plate 9, since the venturi ring 18 is inserted into the downstream block 8 as described later, the passage of the venturi ring 18 becomes the downstream passage 10b of the resin passage 10. There is. As a matter of course, the upstream passage 10a and the downstream passage 10b are located on the same axis.

The slide plate 9 shown in FIG. 2 is composed of a prismatic grip portion 13 to which a handle for rotation operation (not shown) is detachably attached, and a substantially fan-shaped plate-shaped holder portion 14 connected to the grip portion 13. To. As shown in FIGS. 2 to 4, the holder portion 14 has two breakers provided with screens 15a (see FIG. 6) at two locations on the same arc centered on one bolt 11a at predetermined intervals. The plate 15 is detachably provided.

As shown in FIG. 6, the breaker plate 15 is a so-called porous structure in which a large number of through holes are formed to guide the molten resin that has passed through the upstream passage 10a, passed through the screen 15a, and was pumped from the upstream side to the downstream passage 10b. It is a shape. As shown in FIG. 3, each breaker plate 15 is detachably inserted and supported in a support hole 14a formed in the holder portion 14. Then, as shown in FIGS. 2 and 4 and 5, by rotating the slide plate 9 with one bolt 11a as the center of rotation, one of the breaker plates 15 supported by the slide plate 9 is selected. It can be positioned in the resin passage 10.

As shown in FIGS. 2 and 6, the slide plate 9 arranged between the upstream block 7 and the downstream block 8 secures a predetermined gap between the upstream block 7 and the downstream block 8. Has been done. On the other hand, in the upstream block 7, a pressure ring 16 is arranged at the peripheral edge of the opening facing the upstream side surface of the slide plate 9 in the upstream passage 10a. The pressure ring 16 forms a part of the resin passage 10, and as will be described later, has a function of pressure-contacting the holder portion 14 of the slide plate 9 and sealing the portion by the pressure contact force or the adhesion force thereof. Have.

Similarly, in the downstream block 8, a pressure receiving ring 17 as a pressure receiving portion is arranged at an opening peripheral edge portion of the downstream passage 10b facing the downstream side surface of the slide plate 9. As will be described later, when the pressure ring 16 is in pressure contact with the holder portion 14 of the slide plate 9, the pressure receiving ring 17 is pressed against the holder portion 14 while backing up the holder portion 14, and the pressure contact force or the adhesion force is used. It has a function to seal the part. Further, in the downstream block 8, a venturi ring 18 for accelerating the molten resin that has passed through the screen 15a and the breaker plate 15 and pumping it to the downstream side is arranged on the inner peripheral side of the pressure receiving ring 17.

Further, the upstream block 7 is provided with a diameter-expandable seal ring 19 that is in close contact with the pressure ring 16 so as to be adjacent to the upstream side of the pressure ring 16, and is located on the upstream side of the seal ring 19. A pressure receiving ring 20 as a pressure receiving member that is in close contact with the seal ring 19 is arranged. As shown in FIG. 6, the pressure ring 16, the seal ring 19, and the pressure receiving ring 20 provided on the upstream block 7 are fitted and supported by the support recess 7a formed in the upstream block 7. Similarly, the pressure receiving ring 17 provided on the downstream block 8 is fitted and supported by the support recess 8a formed on the downstream block 8.

7 is an enlarged view of the pressure ring 16, the seal ring 19, and the pressure receiving ring 20 shown in FIG. 6, similarly, FIG. 8 is an enlarged perspective view of the seal ring 19, and FIG. 9 is an enlarged perspective view of the seal ring 19. A perspective view of one ring piece 21 which is a component of the above is shown.

As shown in FIGS. 6 and 7, one side surface of the pressure ring 16 is inclined so that its thickness dimension (dimension in the axial direction of FIG. 7) gradually increases from the inner peripheral surface side to the outer peripheral surface side. The surface of the slide plate 9 in contact with the holder 14 is a flat surface, whereas the surface of the slide plate 9 in contact with the adjacent seal ring 19 is formed as a tapered surface 16a. Further, the surface of the pressure receiving ring 20 that comes into contact with the seal ring 19 is also formed as a tapered surface 20a that has a symmetrical shape with the tapered surface 16a on the pressure ring 16 side with the seal ring 19 interposed therebetween. The surface of the pressure receiving ring 20 opposite to the tapered surface 20a is a flat surface, and is seated on the inner bottom surface of the support recess 7a as shown in FIG.

On the other hand, the seal ring 19, which is sandwiched between the pressure ring 16 and the pressure receiving ring 20, has a thickness dimension (dimension in the axial direction of FIG. 7) from the inner peripheral surface side to the outer peripheral surface side as its cross-sectional shape. Both sides are symmetrical and have an inclined shape so that they gradually become smaller. That is, the surface of the seal ring 19 in contact with the pressure ring 16 and the surface in contact with the pressure receiving ring 20 are formed as tapered surfaces 19a and 19b corresponding to the respective tapered surfaces 16a or 20a.

Further, as shown in FIGS. 7 and 8 and 9, the seal ring 19 is divided into a plurality of seal rings 19 in the circumferential direction, and in the present embodiment, four ring pieces 21 having the same shape, and the respective joint surfaces 21a. As shown in FIG. 6, they are arranged in the support recess 7a so as to be sandwiched between the pressure ring 16 and the pressure receiving ring 20. Then, as shown in FIGS. 8 and 9 and FIG. 10 described later, the joint surfaces 21a at both ends of one ring piece 21 are set to be orthogonal to each other, and a seal ring composed of four ring pieces 21 is formed. As shown in FIG. 7, the outer diameter of 19 is set to be slightly smaller than the outer diameter of the pressure ring 16 and the pressure receiving ring 20 on both sides. Therefore, in the state of FIGS. 6 and 7, as will be described later, a radial force acts on the inner peripheral side of the seal ring 19, so that the seal ring 19 is sandwiched between the pressure ring 16 and the pressure receiving ring 20. Is capable of expanding the diameter while sliding on the joint surface 21a between the ring pieces 21.

Therefore, in the screen changer 5 configured in this way, it is assumed that one of the breaker plates 15 is located in the resin passage 10 in the state of FIG. 4 or FIG. 5 and maintains the state of FIG. .. In this state, the molten resin is pumped from the upstream passage 10a toward the downstream passage 10b.

In such a pumping process of the molten resin, when the pumped molten resin passes through the upstream passage 10a, as shown in FIG. 10, the resin pressure acts in the seal ring 19 in the radial direction outward as indicated by the arrow A. Will be done. In response to this resin pressure A, the ring pieces 21 forming the seal ring 19 slide with each other on the joint surface 21a shown in FIG. 10 and by a small amount outward in the radial direction indicated by the arrow B. Will move. That is, the four ring pieces 21 forming the seal ring 19 move slightly outward while forming a slight step on the joint surface 21a on the inner peripheral surface side, and the diameter of the seal ring 19 as a whole is slightly expanded. It will be.

As shown in FIG. 11, as each ring piece 21 forming the seal ring 19 moves in the B direction, the sliding operation between the tapered surfaces 19b and 20a of the seal ring 19 and the pressure receiving ring 20 and the seal ring Based on the sliding operation between the tapered surfaces 19a and 16a of the pressure ring 19 and the pressure ring 16, the seal ring 19 pushes out the pressure ring 16 in the direction of arrow C in the figure.

The pressure ring 16 pressed by the force in the direction of arrow C in FIG. 11 has a downstream side surface located on the slide plate 9 side shown in FIG. 6 pressed against the holder portion 14 of the slide plate 9. Will be pressure-welded or in close contact. As a result, the sealing function between the slide plate 9 supporting the breaker plate 15 and the pressure ring 16 is exhibited. On the other hand, the holder portion 14 of the slide plate 9 that receives the pressure contact force of the pressure ring 16 is pressed against the pressure receiving ring 17 on the downstream side thereof, and both are pressed or brought into close contact with each other. As a result, the sealing function between the slide plate 9 supporting the breaker plate 15 and the pressure receiving ring 17 is exhibited.

Then, in the process of pumping the molten resin as described above, when the molten resin passes through the screen 15a, the foreign matter contained in the molten resin is captured and removed, and further passes through the porous breaker plate 15. , It will be accelerated when passing through the venturi ring 18 on the downstream side thereof, and will be sent out further to the downstream side.

Further, for example, when the pressure feeding operation of the molten resin is stopped at the time of switching the shot operation or changing the setup, the pressure of the molten resin applied to the seal ring 19 decreases, so that the upstream side of the holder portion 14 of the slide plate 9 and the upstream side of the slide plate 9 and The sealing force acting on each of the downstream surfaces will also decrease. As a result, the slide plate 9 can be swiveled, and as shown in FIGS. 4 and 5, the breaker plate 15 can be replaced by switching the position of the holder portion 14.

As described above, according to the present embodiment, the resin pressure of the molten resin to be pumped is positively and effectively utilized, and the holder portion 14 of the slide plate 9 and the pressure ring 16 and the pressure receiving ring on the upper and downstream sides thereof are used. Since the sealing force with 17 is obtained to ensure the sealing property of each, it is possible to prevent the molten resin from leaking out without using a sealing member such as an O-ring. Further, under the seal structure of the present embodiment, as is clear from FIG. 6, since there is no space in which the molten resin stays, it is possible to prevent the molten resin from being burnt.

Here, in the screen changer 5 shown in FIG. 2, the slide type of the slide plate 9 is a swivel type or a swing type, but a linear motion type that moves linearly may also be used. Further, the screen block 6 does not necessarily have to be divided into the upstream block 7 and the downstream block 8, and if the slide plate 9 can be slid, the upstream block 7 and the downstream block 8 can be separated from each other. It may be formed substantially integrally. Further, the number of divisions of the ring piece 21 forming the seal ring 19 is not limited to four, and can be any number. Moreover, the number of breaker plates 15 held on the slide plate 9 can of course be more than two.

FIG. 12 shows a second mode for carrying out the screen changer 5 according to the present invention, and shows a cross-sectional view of a portion equivalent to that of FIG. In the second embodiment shown in FIG. 12, the parts common to those in FIG. 6 are designated by the same reference numerals, and duplicate description will be omitted.

In the screen changer 5 shown in FIG. 12, the pressure receiving block 27 that functions as the pressure receiving portion of the downstream side block 8 is integrally formed with the downstream side block 8 itself. Therefore, in this second embodiment as well, the same actions and effects as those in the first embodiment will be exhibited.

13 and 14 show a third embodiment for carrying out the screen changer 5 according to the present invention, FIG. 13 shows a cross-sectional view of a portion equivalent to that of FIG. 6, and FIG. 14 shows a cross-sectional view of the same portion as that of FIG. The enlarged view of the main part of is shown. Also in the third embodiment shown in FIGS. 13 and 14, the same reference numerals are given to the parts common to those in FIGS. 6 and 7, and duplicate description will be omitted.

In the screen changer 5 shown in FIGS. 13 and 14, as is clear from comparison with FIGS. 6 and 7, the seal ring 19 shown in FIGS. 6 and 7 and the pressure receiving ring 20 on the upstream side thereof are integrally formed to be wide. This is the seal ring 29 of. In the third embodiment, only the surface of the seal ring 29 in contact with the pressure ring 16 on the downstream side is a tapered surface 19a, and the surface on the upstream side of the seal ring 29 is a flat surface. , This flat surface is seated on the inner bottom surface of the support recess 7a. Further, since the seal ring 29 can be expanded in diameter in the same manner as those shown in FIGS. 7 and 8, the outer diameter of the entire seal ring 29 shown in FIGS. 13 and 14 is the seal ring 19 shown in FIGS. 7 and 8. It is set to the same size as the outer diameter of. Further, the divided form of the ring piece 31 forming the seal ring 29 is the same as in FIGS. 8 and 9. Therefore, in this third embodiment as well, the same actions and effects as those in the first embodiment will be exhibited.

FIG. 15 shows a side view of the hollow molding machine provided with the extruder 1 shown in FIG. 1 as an example.

The hollow forming machine shown in FIG. 15 includes the extruder 1 shown in FIG. 1, a head 22 connected to the downstream side of the screen changer 5 of the extruder 1 to extrude and hang a tubular parison, and a lower portion of the head 22. A molding die (not shown) that receives the parison hanging from the head 22 and forms it into a predetermined hollow molded product shape. The extruder 1 is provided on the gantry 23 of the hollow forming machine. Further, the hollow molding machine shown in FIG. 15 has a mold clamping device for opening / closing and clamping a molding die, a parison cutting device for cutting a hanging parison to a predetermined length, and a molding die at a predetermined position. It is equipped with a mold transfer device that moves back and forth between molds, an air blowing device that supplies compressed air inside the parison housed in the molding mold, and an extraction device that takes out the molded product, but it is an essential part of the invention. Since it is not directly related, the illustration is omitted.

Therefore, in this hollow molding machine, the molten resin that has passed through the extruder 1 and the head 22 is extruded from the head 22 as a tubular parison, hangs down, is housed in an open molding die, and is molded by a mold clamping device. In this state, it is transferred directly under the air blowing device by the mold transfer device. The air blowing device lowers the driving nozzle and drives it into the molding die, blows compressed air into the parison in the molding die, and presses the expanded parison into the cavity in the molding die to form the molded product shape. ..

According to this hollow molding machine, since the screen changer 5 described above is provided, foreign matter in the molten resin is surely captured and removed by the screen changer 5, and if there is no resin leakage, the resin is used. It is possible to obtain a good molded product without causing scorching.

In the above embodiment, the extruder 1 for extruding the molten resin and the hollow molding machine provided with the extruder 1 have been described as an example. However, the screen changer 5 of the above embodiment includes the extruder 1 and the extruder 1. Not limited to the hollow molding machine provided with the extruder 1, it can also be applied as a screen changer interposed in a pumping path for pumping a relatively viscous fluid, for example, in various production facilities and manufacturing plants.

1 ... Extruder 4 ... Heating cylinder 5 ... Screen changer 6 ... Screen block 9 ... Slide plate 10 ... Resin passage (fluid pumping flow path)
15 ... Breaker plate 15a ... Screen 16 ... Pressurized ring 16a ... Tapered surface 17 ... Pressure receiving ring (pressure receiving part)
19 ... Seal ring 19a ... Tapered surface 21 ... Ring piece 22 ... Head

Claims (4)

A screen block on which a fluid pumping flow path is formed, a slide plate slidably mounted in a direction crossing the fluid pumping flow path of the screen block, and a screen that is detachably supported by the slide plate and is provided. With at least two perforated breaker plates,
A screen changer in which the breaker plate supported by the slide plate is positioned in the fluid pumping flow path of the screen block by the sliding operation of the slide plate.
A pressure ring is provided on the upstream side surface of the slide plate to form the fluid pressure feed flow path, and a pressure ring is provided.
A seal ring capable of increasing the diameter is provided adjacent to the upstream side of the pressure ring.
A pressure receiving ring is provided so as to face the downstream side surface of the slide plate and form the fluid pressure feeding flow path.
The seal ring is divided into four ring pieces having the same shape in the circumferential direction, and the joint surfaces of the ring pieces are abutted to form a ring shape so that the joint surfaces at both ends of each ring piece are orthogonal to each other. Ring pieces that are set and face each other in the radial direction across the center of the seal ring have one joint surface parallel to one radial direction passing through the center of the seal ring and the other joint surface. The seal is parallel to the other radial direction orthogonal to the one radial direction, and the one joint surface and the other joint surface of the ring pieces adjacent in the circumferential direction are slid. The ring and the pressure ring are in contact with each other on a tapered surface.
The screen changer is characterized in that the pressure ring is brought into pressure contact with the slide plate by expanding the diameter in response to the pressure of the fluid flowing in the fluid pressure feeding flow path. The screen changer according to claim 1, wherein the slide plate is a swing type that slides while swinging in a direction crossing a fluid pressure feeding flow path of the screen block. An extruder according to claim 1 or 2, wherein the screen changer is provided at the tip of a heating cylinder that extrudes a molten resin material. An extruder with a heating cylinder that extrudes the molten resin material,
A head that gives a shape to the molten resin extruded from the heating cylinder, and
At least have
A hollow molding machine according to claim 1 or 2, wherein the screen changer is provided between the extruder and the head.

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