JP2018126867A - Screen changer, extruder using the same, and blow molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of a molten resin without using an O-ring or the like, and to prevent secondary defects such as burns caused by stagnation of the molten resin.SOLUTION: A screen changer comprises: a slide plate 9 slidable in a direction crossing a resin passage 10 of a screen block 6; and two porous breaker plates 15, provided in the slide plate 9, including a screen 15a. The screen changer comprises: a pressure ring 16 provided in the upstream side of the slide plate 9 in the resin passage 10; a diameter-expandable seal ring 19 adjacent to the pressure ring 16; and a pressure receiving ring 17 provided in the downstream side of the slide plate 9 in the resin passage 10. The pressure ring 16 is pressed against the slide plate 9 for sealing due to the seal ring 19 expanding by receiving pressure from a molten resin flowing in the resin passage 10.SELECTED DRAWING: Figure 6

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 matters in the fluid, and an extruder and a hollow molding machine using the screen changer.

  An 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 rotationally driven. A head for imparting a shape to the extruded molten resin is attached to the tip of the heating cylinder, and a screen changer having a screen for capturing and removing foreign matter in the molten resin is provided upstream of the head. Is provided. As a typical example of such a screen changer, for example, one disclosed in Patent Document 1 is known.

  The screen mounting structure for an extruder disclosed in Patent Document 1 includes a pressure ring that presses the screen against the outer ring, and an adjustment ring that adjusts the pressing force of the pressure ring. A contact portion between the pressure ring and the adjustment ring is provided with a fitting portion including 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 in which the concave and convex fitting portion is formed is merely pressed by a mechanical external force due to a screw, the resin is increased 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 that uses a plurality of O-rings as seal members. In the structure of the screen changer disclosed in Patent Document 2, after using a plurality of O-rings as a seal member, each of the first ring body, the second ring body, and the breaker plate holding the screen, It is made to press-contact with the boss | screw screwed in from the downstream of the flow direction of molten resin.

  Moreover, what was disclosed by patent document 3 as a screen changer which paid its attention to the quickness of the replacement | exchange operation | work of the filter which has a screen is proposed. In the screen changer disclosed in Patent Document 3, a plurality of filters are prepared in advance in a filter carrier assembly slidable in a direction crossing the polymer flow passage, and the filter is replaced by sliding the filter carrier assembly. It can be done quickly. A polymer seal is employed for sealing the polymer flow passage and the filter.

JP-A-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 always receives the pressure and heat of the molten resin. There is a concern that the durability may be reduced due to damage.

  This also applies to the structure disclosed in Patent Document 3 in which a polymer seal is employed for sealing the polymer flow passage and the filter. In addition, in the polymer seal disclosed in Patent Document 3 in particular, an annular recess is formed on the upstream side in the polymer flow direction of the seal itself, so that the molten polymer (molten resin) is retained in the annular recess. There was a risk of causing scorching of the molten resin. If the molten resin that has been burnt is mixed in a molded product, it may cause an appearance defect of the molded product and the like.

  For this reason, it is desirable to employ a seal structure that does not use an O-ring or a polymer seal in order to prevent the burnt of the molten resin while improving the durability of the sealing member that controls the seal.

  The present invention has been made paying attention to such a problem. Like the one disclosed in Patent Document 3, the present invention includes at least two porous breaker plates each having a screen. Providing a screen changer that can prevent the pumping fluid from leaking without using an O-ring or polymer seal, and prevent secondary problems such as scorching of the pumping fluid, while ensuring the speed of replacement. To do. Furthermore, an extruder and a hollow molding machine using the screen changer are provided.

  The present invention includes a screen block in which a fluid pressure feed channel is formed, a slide plate that is slidably mounted in a direction across the fluid pressure feed channel of the screen block, and is detachably supported by the slide plate. And at least two porous breaker plates each having a screen, and the slide plate supported by the slide plate is positioned in the fluid pressure-feed passage of the screen block by the sliding operation of the slide plate. It is a screen changer designed to let you.

  In addition, a pressure ring that forms the fluid pressure-feed passage facing the upstream side surface of the slide plate is provided, and a seal ring that can be expanded in diameter is provided adjacent to the upstream side of the pressure ring, A pressure receiving ring is provided which faces the downstream side surface of the slide plate and forms the fluid pressure feeding passage. The seal ring is configured to be brought into pressure contact with the slide plate by expanding the diameter by receiving the pressure of the fluid flowing in the fluid pumping flow path. .

  The screen changer according to the present invention is mainly provided at the tip of the heating cylinder in the extruder, but the 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.

  As the function of the seal ring, while forming a part of the fluid pressure-feeding channel, the diameter of the fluid is increased by receiving the pressure of the fluid flowing in the fluid pressure-feeding channel, and the pressure ring adjacent to the pressure ring is set against the slide plate. It is to be pressed. As a more specific aspect, the seal ring is divided into a plurality of ring pieces in the circumferential direction, and each ring piece expands while sliding, and the seal ring and the pressure ring It is desirable that the ring comes into contact with the tapered surface.

  Such a seal ring made up of a plurality of ring pieces can smoothen the movement of each ring piece in the outer circumferential direction due to the pressure of the fluid to be pumped to make the sealing force uniform in the ring circumferential direction and increase the sealing force. It 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 better. However, for example, about 4 to 8 pieces are desirable from the viewpoint of manufacturing.

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

  The screen block may be integrated as long as the slide plate can be slidably supported. However, when considering the assembly with other related members, the screen blocks are respectively provided. It is desirable to have an upstream block and a downstream block in which a fluid pumping flow path is formed, and a slide plate is disposed between the upstream block and the downstream block.

  The slide type of the slide plate may be a direct acting type similar to that described in Patent Document 3, but as a form considering the space efficiency, the slide plate swings in a direction crossing the fluid pumping flow path of the screen block. A so-called swing type that slides while moving is desirable.

  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 receiving the diameter expansion force, so that the two come into pressure contact with each other. Thereby, the sealing performance of the breaker plate located in the fluid pressure feeding flow path is ensured. In this case, the pressure receiving portion serves as a backup for the slide plate against which the pressure ring is pressed.

  According to the present invention, it is possible to ensure the sealing performance of the breaker plate located in the fluid pumping flow path without using a sealing member such as an O-ring, and to prevent leakage of the pumping fluid, Problems such as scorching will not occur.

The side view which shows an example of the extruder with which the screen changer is applied as 1st Embodiment of the screen changer which concerns on this invention. The expansion perspective view of the screen changer shown in FIG. The disassembled perspective view of the principal part of the screen changer shown in FIG. Explanatory drawing which shows the motion of the screen changer shown in FIG. Explanatory drawing which similarly shows the movement of the screen changer shown in FIG. The longitudinal cross-sectional view of the screen changer shown in FIG. The enlarged view of the principal part of FIG. The perspective view of the seal ring shown in FIG. The perspective view of one ring piece which forms the seal ring shown in FIG. FIG. 9 is a functional explanatory diagram of the seal ring shown in FIG. 8. Functional explanatory drawing of the seal ring shown in FIG. The figure which shows 2nd Embodiment of the screen changer which concerns on this invention, and is a longitudinal cross-sectional view of a site | part equivalent to FIG. The figure which shows 3rd Embodiment of the screen changer which concerns on this invention, and is a longitudinal cross-sectional view of a site | part equivalent to FIG. The enlarged view of the principal part of FIG. The side view of the hollow molding machine provided with the extruder of FIG.

  FIGS. 1-11 shows the 1st form for implementing the screen changer which concerns on this invention, Especially FIG. 1 is an example of the extruder for hollow molding machines (blow molding machine) to which the screen changer which concerns on this invention was applied. The outline is shown.

  An extruder 1 shown in FIG. 1 is installed on a frame of a molding machine (not shown), and has a hopper 2, a screw 3, a heating cylinder (barrel) 4 in which the screw 3 is built, 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 portion, a compression portion, and a metering portion in order from the hopper 2 side where the base end is located toward the tip.

  The feed part is a boundary where the resin pellets supplied from the hopper 2 of the extruder 1, that is, a solid resin is transported while being heated toward the tip of the screw 3, and the pitch interval is equal from the base end to the tip of the screw 3. And a main flight arranged in a spiral shape. The groove depth of the feed part is constant and is always set larger than the compression part and the measurement part.

  The compression part is an area that accelerates the melting of the resin by pressurizing and compressing partially heated and partially melted resin in the feed part and supplying mechanical energy, and is configured by the main flight that continues from the feed part A subflight that obliquely crosses the main flight is provided in the screw groove to form a melt-promoting portion of the molten resin.

  The metering unit is a region for rectifying by promoting homogenization of the resin that has been almost melted in the compression unit, and has a main flight that continues from the main flight of the compression unit, and in the screw groove between adjacent main flights. Has a subflight.

  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 the molten resin part and the solid phase resin part by the subflight of the compression part. In the solid phase resin part, the shear heat generation works effectively to improve the melting ability, and the melting is stabilized and melted. Is also promoted.

  The molten resin that has been pumped from the compression unit to the metering unit is further mixed in the metering unit by being disturbed in its flow, and is swept away in a homogeneous state and pumped to the screen changer 5. In the screen changer 5, foreign matters in the molten resin are captured and removed and pumped downstream. 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 the main part of the screen changer 5 shown in FIG. 2, and FIGS. 4 and 5 are screens shown in FIG. The movement of the changer 5 is shown respectively. FIG. 6 is a longitudinal sectional view of the screen changer 5 shown in FIG.

  As shown in FIG. 2, the screen changer 5 includes a screen block 6 having a resin passage 10 (see FIG. 6) serving as a fluid passage for a molten resin as a fluid pumping passage, and a screen block 6 that can be inserted into and removed from the screen block 6. And 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 has an upstream formed with a resin passage 10 in the axial direction through which the molten resin to be pumped flows. A side block 7 and a downstream block 8 are provided. As shown in FIGS. 1 and 6, the upstream block 7 and the downstream block 8 are composed of a plurality (three in this case) of bolts 11a and 11b and a collar 12 inserted in each of the bolts 11a and 11b. The distance between the two is fixed by the collar 12.

  Furthermore, a slide plate 9 is disposed between the upstream block 7 and the downstream block 8, and one bolt 11 a and the collar 12 inserted into the bolt 11 a and 11 b are connected to the slide plate 9. Is supported rotatably and removably. In other words, the slide plate 9 disposed between the upstream block 7 and the downstream block 8 is formed as a so-called swivel type or swing type that can swing around a single bolt 11a. Has been.

  Here, as shown in FIG. 6, a portion of the resin passage 10 on the upstream block 7 side with respect to the slide plate 9 across the slide plate 9 is referred to as an upstream passage 10 a. On the other hand, since the venturi ring 18 is inserted into the downstream block 8 on the downstream side of the slide plate 9 as described later, the passage of the venturi ring 18 becomes the downstream side passage 10b of the resin passage 10. Yes. 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 includes a prismatic grip portion 13 to which a rotation operation handle (not shown) is detachably attached, and a substantially fan-shaped plate-like holder portion 14 connected to the grip portion 13. The As shown in FIGS. 2 to 4, the holder portion 14 includes two breakers each having a screen 15 a (see FIG. 6) at two predetermined positions on the same arc with the single bolt 11 a as the rotation center. The plate 15 is detachably provided.

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

  As shown in FIGS. 2 and 6, the slide plate 9 disposed 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. On the other hand, in the upstream block 7, a pressure ring 16 is disposed at the opening peripheral edge facing the upstream side surface of the slide plate 9 in the upstream passage 10 a. The pressure ring 16 forms a part of the resin passage 10 and, as will be described later, has a function of pressing the holder portion 14 of the slide plate 9 and sealing the portion with the pressing force or adhesion force. Have.

  Similarly, in the downstream block 8, a pressure receiving ring 17 as a pressure receiving portion is disposed at an opening peripheral edge facing the downstream side surface of the slide plate 9 in the downstream passage 10 b. 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 in pressure contact with the holder portion 14 being backed up, and the pressure contact force or adhesion force It has the function of sealing the part. In the downstream block 8, a venturi ring 18 for accelerating the molten resin that has passed through the screen 15 a and the breaker plate 15 and feeding it to the downstream side is disposed on the inner peripheral side of the pressure receiving ring 17.

  Further, the upstream block 7 is provided with an 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 on the upstream side of the seal ring 19. A pressure receiving ring 20 is disposed as a pressure receiving member in close contact with the seal ring 19. As shown in FIG. 6, the pressure ring 16, the seal ring 19, and the pressure receiving ring 20 provided in the upstream block 7 are fitted and supported in a support recess 7 a formed in the upstream block 7. Similarly, the pressure receiving ring 17 provided in the downstream block 8 is fitted and supported in a support recess 8 a formed in 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 a seal ring 19. The perspective view of the one ring piece 21 which is a component of is shown, respectively.

  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 in FIG. 7) gradually increases from the inner peripheral surface side toward the outer peripheral surface side. The surface that contacts the holder 14 of the slide plate 9 is a flat surface, whereas the surface that contacts 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 is symmetrical to the tapered surface 16a on the pressure ring 16 side with the seal ring 19 interposed therebetween. In addition, the surface on the opposite side to the taper surface 20a of the pressure receiving ring 20 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 that is sandwiched between the pressure ring 16 and the pressure receiving ring 20 has a cross-sectional shape with a thickness dimension (dimension in the axial direction in FIG. 7) from the inner peripheral surface side to the outer peripheral surface side. Both sides are symmetrical and inclined so as to gradually become smaller. That is, the surface of the seal ring 19 that contacts the pressure ring 16 and the surface that contacts 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, 8, and 9, the seal ring 19 is divided into a plurality of ring pieces 21 having the same shape in the circumferential direction, and in this embodiment, four ring pieces 21 having the same shape. As shown in FIG. 6, it is arranged in the support recess 7 a so as to be sandwiched between the pressure ring 16 and the pressure receiving ring 20. As shown in FIGS. 8 and 9 and FIG. 10 to be described later, the joint surfaces 21 a at both ends of one ring piece 21 are set so as to be orthogonal to each other, and a seal ring comprising four ring pieces 21. As shown in FIG. 7, the outer diameter of 19 is set slightly smaller than the outer diameters 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, the seal ring 19 is sandwiched between the pressure ring 16 and the pressure receiving ring 20 by the radial force acting on the inner peripheral side of the seal ring 19. The diameter can be increased while sliding on the joint surface 21a between the ring pieces 21.

  Therefore, in the screen changer 5 configured as described above, it is assumed that one of the breaker plates 15 is positioned in the resin passage 10 in the state of FIG. 4 or 5 and the state of FIG. 6 is maintained. . In this state, the molten resin is pumped from the upstream side passage 10a toward the downstream side passage 10b.

  In such a molten resin pumping process, when the pumped molten resin passes through the upstream passage 10a, the resin pressure acts radially outwardly as indicated by an arrow A in the seal ring 19 as shown in FIG. Will do. Receiving this resin pressure A, each ring piece 21 forming the seal ring 19 slides on the joint surface 21a shown in FIG. Will move. That is, the four ring pieces 21 forming the seal ring 19 slightly move outward while causing 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 increased. It will be.

  As the respective ring pieces 21 forming the seal ring 19 move in the B direction, as shown in FIG. 11, the sliding movement between the taper surfaces 19b and 20a of the seal ring 19 and the pressure receiving ring 20, and the seal ring On the basis of the sliding motion between the tapered surfaces 19a and 16a of the pressure ring 19 and the pressure ring 16, the seal ring 19 pushes 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 the arrow C in FIG. 11 has its downstream side surface located on the slide plate 9 side shown in FIG. Will be in pressure contact or close contact. Thereby, 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, so that the two are in pressure contact or in close contact with each other. Thereby, the sealing function between the slide plate 9 supporting the breaker plate 15 and the pressure receiving ring 17 is exhibited.

  In the process of feeding the molten resin as described above, when the molten resin passes through the screen 15a, foreign substances contained in the molten resin are captured and removed, and further, after passing through the porous breaker plate 15. , It is accelerated when passing through the venturi ring 18 on the downstream side, and is further sent to the downstream side.

  Further, for example, when the molten resin pumping operation 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 sealing force acting on the downstream side surface is also reduced. As a result, the slide plate 9 can be turned, and the breaker plate 15 can be replaced by switching the position of the holder portion 14 as shown in FIGS.

  Thus, according to the present embodiment, the resin portion of the molten resin to be pumped is positively and effectively used, and the holder portion 14 of the slide plate 9, the pressure ring 16 and the pressure receiving ring on the upstream and downstream sides thereof. Since the sealing force is obtained with the sealing member 17 and the respective sealing properties are secured, leakage of the molten resin can be prevented without using a sealing member such as an O-ring. Further, under the seal structure of the present embodiment, as is apparent from FIG. 6, there is no space where the molten resin stays, so that 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 swing type or a swing type, but it may be a linear type that moves linearly. Further, the screen block 6 is not necessarily divided into the upstream block 7 and the downstream block 8, and if the sliding movement of the slide plate 9 is possible, the upstream block 7 and the downstream block 8 are separated. It may be formed substantially integrally. Furthermore, the number of divisions of the ring piece 21 forming the seal ring 19 is not limited to four, and can be any number. In addition, the number of breaker plates 15 held on the slide plate 9 may be more than two.

  FIG. 12 shows a second embodiment for implementing the screen changer 5 according to the present invention, and shows a cross-sectional view of a portion equivalent to FIG. In the second embodiment shown in FIG. 12, parts common to those in FIG. 6 are denoted by the same reference numerals, and redundant description is omitted.

  In the screen changer 5 shown in FIG. 12, a pressure receiving block 27 that functions as a pressure receiving portion of the downstream block 8 is formed integrally with the downstream block 8 itself. Therefore, also in the second embodiment, the same operations and effects as the first embodiment are exhibited.

  13 and 14 show a third embodiment for implementing the screen changer 5 according to the present invention. FIG. 13 shows a cross-sectional view of the same portion as FIG. 6, and FIG. 14 shows FIG. The enlarged view of the principal part of is shown. In the third embodiment shown in FIGS. 13 and 14 as well, the same reference numerals are given to portions common to FIGS.

  In the screen changer 5 shown in FIGS. 13 and 14, the seal ring 19 shown in FIGS. 6 and 7 and the pressure-receiving ring 20 on the upstream side thereof are integrally formed so as to be wide as apparent from the comparison with FIGS. The seal ring 29 is used. In the third embodiment, only the surface in contact with the pressure ring 16 on the downstream side of the seal ring 29 is a tapered surface 19a, and the upstream surface of the seal ring 29 is a flat surface. The flat surface is seated on the inner bottom surface of the support recess 7a. Further, since the seal ring 29 can be enlarged in diameter as 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. It is set to the same size as the outer diameter of. Furthermore, the division form of the ring piece 31 forming the seal ring 29 is the same as that shown in FIGS. Therefore, also in the third embodiment, the same operations and effects as those of the first embodiment are exhibited.

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

  A hollow molding machine shown in FIG. 15 includes an extruder 1 shown in FIG. 1, a head 22 that is connected to the downstream side of the screen changer 5 of the extruder 1 to extrude and suspend a cylindrical parison, and below the head 22. And a molding die (not shown) that receives the parison suspended from the head 22 and molds it into a predetermined hollow molded product shape. The extruder 1 is provided on a frame 23 of a hollow molding machine. Further, the hollow molding machine shown in FIG. 15 includes a mold clamping device that opens / closes and molds a molding die, a parison cutting device that cuts a suspended parison into a predetermined length, and a molding die at a predetermined position. A die transfer device that reciprocates between them, an air blowing device that supplies compressed air to the inside of the parison accommodated in the molding die, a take-out device that takes out the molded product, and the like. Since there is no direct relationship, 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 cylindrical parison, hangs down, is accommodated in an open molding die, and is clamped by a mold clamping device. In this state, it is transferred directly below 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 against the cavity in the molding die to form a molded product shape. .

  According to this hollow molding machine, since the screen changer 5 described above is provided, the foreign material in the molten resin is surely captured and removed by the screen changer 5 and there is no occurrence of resin leakage. Thus, it is possible to obtain a good molded product.

  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 examples. However, the screen changer 5 of the above embodiment includes the extruder 1, The present invention is not limited to the hollow molding machine provided with the extruder 1, and 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.

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

Claims (5)

A screen block in which a fluid pressure-feed passage is formed; a slide plate that is slidably mounted in a direction across the fluid pressure-feed passage of the screen block; and a screen that is detachably supported by the slide plate and includes a screen A porous at least two breaker plates,
A screen changer in which the breaker plate supported by the slide plate is positioned in a fluid pressure feeding flow path of the screen block by a sliding operation of the slide plate,
While providing a pressure ring that forms the fluid pressure-feed passage facing the upstream side surface of the slide plate,
A seal ring capable of expanding the diameter is provided adjacent to the upstream side of the pressure ring,
Provided with a pressure receiving ring that faces the downstream side surface of the slide plate and forms the fluid pressure feeding passage,
The screen changer according to claim 1, wherein the seal ring is expanded in diameter by receiving the pressure of the fluid flowing in the fluid pumping flow path, so that the pressure ring is pressed against the slide plate. The seal ring is divided into a plurality of ring pieces in the circumferential direction, and the diameter of each ring piece is increased while sliding,
The screen changer according to claim 1, wherein the seal ring and the pressure ring are in contact with each other at a tapered surface.   3. The screen changer according to claim 1, wherein the slide plate is of a swing type that slides while swinging in a direction crossing the fluid pressure feeding flow path of the screen block.   An extruder, wherein the screen changer according to any one of claims 1 to 3 is provided at a tip portion of a heating cylinder for extruding a molten resin material. An extruder having a heating cylinder for extruding molten resin material;
A head for imparting a shape to the molten resin extruded from the heating cylinder;
At least,
A hollow molding machine, wherein the screen changer according to any one of claims 1 to 3 is provided between an extruder and a head.

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