JP2013049198A - Extrusion die of broad-line plate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extrusion die of a broad-line plate resin of which a flow rate can be uniformized much more by focusing a shape of an end of branch passage.SOLUTION: The extrusion die 1 of the broad-line plate resin includes an expansion part 5 that continues to on an outlet-side end of the respective branch passages 4 at a final stage of a branch resin passage and leads to a flat plate resin passage 6 while expanding the range the expansion part. In the expansion part 5, a pair of branch parts 9 are provided which continue to the outlet-side end of the respective branch passages 4 at the final stage, are deeper that the flat plate resin passage 6, and gradually narrow a passage width to continue to the flat plate resin passage 6.

Description

  The present invention relates to a wide plate resin extrusion mold for extruding a thermoplastic resin into a wide plate shape.

  As a mold for extruding a wide plate resin, Patent Document 1 discloses a resin inlet passage, a branched resin passage connected to the resin inlet passage and composed of a plurality of stages of branched passages, a flat resin passage connected to the resin outlet, A device is disclosed that includes a development portion that extends to the flat resin passage while expanding the width of the branch passage in the final stage of the branch resin passage.

  In the thing of patent document 1, each expansion | deployment part is made into the coat hanger-like thing of the same depth as a flat resin path, and extrusion resin is made into flat form immediately after exiting each branch passage of the last stage. ing.

  Each branch passage includes an upstream portion connected to the resin inlet passage or the upstream branch passage, and a downstream portion that is bent with respect to the upstream portion and extends in the resin extrusion direction. The angle formed by the passage or the upstream branch passage and the angle formed by the upstream portion and the downstream portion are both perpendicular.

International Publication No. WO2005 / 115720

  According to the mold for extruding a wide plate resin in Patent Document 1 described above, a branch resin passage made up of a plurality of stages of branch passages is provided, so that a thermoplastic resin, in particular, a thermoplastic resin containing a foaming agent can be widened. When a resin sheet is produced by extruding into a plate shape, there is an advantage that the flow rate of the thermoplastic resin in the width direction and the thickness direction of the thermoplastic resin can be made uniform.

  The thing of the said patent document 1 describes providing the coat hanger-like expansion | deployment part, However, The expansion | deployment part is made into flat form and it is not taking into consideration the shape of the edge part of the branch passage of the last stage. It was not done.

  Further, in the above-mentioned Patent Document 1, it is described that the length of the resin passage is taken into account so that the resin pressure (back pressure) in the width direction in the resin reservoir becomes uniform. Since the angle formed by the resin inlet passage or the upstream branch passage and the angle formed by the upstream portion and the downstream portion are both at right angles, the resistance at the right angle portion increases and the back pressure increases. There was a problem of becoming.

  An object of the present invention is to provide a die for extruding a wide plate-like resin capable of further uniforming the flow rate by paying attention to the shape of the end of the branch passage, which has not been considered in the past.

  Another object of the present invention is to provide a mold for extruding a wide plate resin that can reduce back pressure.

  A wide plate-shaped resin extrusion mold according to the present invention includes a resin inlet passage, a branch resin passage connected to the resin inlet passage and formed of a plurality of stages of branch passages, a flat resin passage connected to the resin outlet, and a branch resin passage. In the wide plate-shaped resin extrusion mold, the width of the final stage is extended to the outlet side end of each branch passage and the width of the width is expanded to reach the flat resin passage. A pair of branch portions that are connected to the outlet side end of each of the branch passages, are deeper than the plate-like resin passage and gradually narrow in the passage width, and are connected to the plate-like resin passage. is there.

  Each development portion is provided with a pair of branch portions that are continuous with the outlet side end portion of each branch passage in the final stage, and that are deeper than the flat resin passage and gradually narrow in the passage width and continue to the flat resin passage. As a result, the flow rate of the resin in the width direction can be made uniform, and the flow rate can be made even more uniform.

  The branch resin passage is composed of two first-stage branch passages branched from the resin inlet passage and a total of four second-stage branch passages branched from the first-stage branch passages. In addition, there may be a total of eight third-stage branch passages branched from the respective second-stage branch passages. In the former case, the final stage = second stage, and in the latter case, the final stage = third stage.

  Each branch passage includes an upstream portion connected to the resin inlet passage or the upstream branch passage, and a downstream portion that is bent with respect to the upstream portion and extends in the resin extrusion direction, and the upstream portion and the resin inlet passage or It is preferable that the angle formed by the upstream branch passage and the angle formed by the upstream portion and the downstream portion are both obtuse.

  By making an obtuse angle (the value is not particularly limited as long as it is greater than 90 °), the flow of the resin becomes smooth and the back pressure can be further reduced. The above-mentioned “obtuse angle” can be rephrased as “the upstream portion of each branch passage is inclined with respect to the extrusion direction and the width direction perpendicular thereto”.

  It is preferable that the butt portion of the wall surface forming the upstream portion of each branch passage is positioned upstream of the intersection of the extension lines of the wall surfaces forming the upstream portion.

  Wall surfaces that form the upstream portion of each branch passage by making the angle formed by the upstream portion and the resin inlet passage or the upstream branch passage and the angle formed by the upstream portion and the downstream portion both obtuse However, it is advantageous to reduce the back pressure by providing the butted portion so that the butted portion is positioned further upstream than the tip position of the V-shaped portion that is normally obtained. It becomes possible to further reduce the pressure.

  According to the wide plate-like resin extrusion die of the present invention, each unfolded portion is connected to the outlet side end of each branch passage in the final stage, and is deeper than the flat resin passage and the passage width gradually becomes narrower. By providing a pair of branch portions connected to the resin-like resin passage, the flow rate of the resin in the width direction can be made uniform, and the flow rate can be made even more uniform.

FIG. 1 is a plan view showing an embodiment of a wide plate resin extrusion die according to the present invention. 2A is a cross-sectional view taken along the line AA in FIG. 1, FIG. 2B is a cross-sectional view taken along the line BB in FIG. 1, and FIG. 2 is a cross-sectional view taken along line CC of FIG. 1, FIG. 2D is a cross-sectional view taken along line DD in FIG. 1, and FIG. 2E is taken along line EE in FIG. It is sectional drawing. FIG. 3 is a perspective view of a wide plate resin extrusion mold according to the present invention. FIG. 4 is a graph showing the flow rate ratio of the wide plate resin extrusion mold according to the present invention in comparison with the comparative example. FIGS. 5A and 5B are diagrams showing a wide plate-like resin extrusion mold according to a comparative example, in which FIG. 5A corresponds to FIG. 1 and FIG. 5B corresponds to FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the left and right refer to the left and right in FIG.

  1 to 3 show a mold for extruding a wide plate resin according to the present invention.

  The extrusion mold (1) includes a resin inlet passage (2), two first-stage branch passages (3) branched from the resin inlet passage (2) so as to be symmetrical, and each first stage. A total of four second-stage branch passages (4) branched in a symmetrical manner from the eye branch passage (3), and a meter provided at the end of each second-stage branch passage (4) There are provided four developed portions (5) and a flat resin passage (6) having a width of a wide plate resin to be manufactured and continuing to a resin outlet (7).

  This extrusion mold (1) is a lower mold, and is used in combination with an upper mold having a flat surface except for the resin inlet passage portion. At this time, the portion where the passage is not provided is in close contact with the flat surface of the upper mold, and the passage formed in the lower mold (resin inlet passage (2), branch passage (3) (4), deployment portion (5) In addition, the resin flows only through the flat resin passage (6)).

  The extrusion mold (1) is connected to a monoaxial or biaxial extruder and is used for producing a thermoplastic resin sheet, a thermoplastic resin foam sheet, and the like.

  The resin inlet passage (2) is provided at the center in the width direction so as to extend in the extrusion direction.

  The first-stage branch passage (3) includes an upstream portion (3a) continuous with the resin inlet passage (2) and a downstream portion (3b) that is bent with respect to the upstream portion (3a) and extends in the extrusion direction. It consists of. The downstream part (3b) of the left first stage branch passage (3) is provided so as to be located at the center of the left half of the resin outlet (7). The downstream part (3b) of the branch passage (3) is provided so as to be located at the center of the right half of the resin outlet (7).

  The second-stage branch passage (4) includes an upstream portion (4a) continuous with the first-stage branch passage (3) and a downstream side that is bent with respect to the upstream portion (4a) and extends in the extrusion direction. It consists of part (4b). The downstream portion (4b) of each branch passage (4) is provided so as to be located at the exact center of the width obtained by dividing the resin outlet (7) into four equal parts.

  A branched resin passage is formed by the two first-stage branch passages (3) and the four second-stage branch passages (4).

  In each branch passage (3) (4), the angle formed by the upstream portion (3a) (4a) and the upstream passage (resin inlet passage (2) or first-stage branch passage (3)) and The angles formed by the upstream portions (3a) and (4a) and the downstream portions (3b) and (4b) are both obtuse angles.

  Each development portion (5) has a substantially isosceles triangle in plan view, the upstream width is equal to the width of the second-stage branch passage (4), which is the final-stage branch passage, and the downstream width is flat. The total width of the flat resin passages (6) is made equal to ¼ of the total width of the plate-shaped resin passages (6).

  Each development part (5) is connected to the flat resin passage (6) and has the same depth as the flat resin passage (6), and isosceles triangular part (8) and isosceles triangle part (8). The passage width on the upstream side is equal to ½ of the passage width of the second-stage branch passage (4), and the passage width gradually becomes narrower toward the downstream side thereafter. It consists of a pair of branch parts (9) connected to the resin passage (6).

  The butted portions (P1) and (P2) of the wall surfaces forming the upstream portions (3a) and (4a) of the respective branch passages (3) and (4) indicated by P1 and P2 in FIG. It is located upstream of the intersection (Q1) (Q2) of the extension line of the wall surface forming 4a).

  The flat resin passage (6) is provided with one resin reservoir (10) orthogonal to the resin flow direction. The resin reservoir (10) is formed in a groove shape having a substantially trapezoidal cross section.

  As shown in FIG. 2, the first-stage branch passage (3) is smaller in width and depth than the resin inlet passage (2), and the second-stage branch passage (4 ) Is smaller in width and almost the same depth as the first-stage branch passage (3), and the isosceles triangular portion (8) of the developed portion (5) has a flat resin passage. Same as (6), the branch part (9) of the expanded part (5) is deeper than the isosceles triangle part (8) (and therefore deeper than the flat resin passage (6)). .

  As shown in FIG. 5, the coat hanger-shaped development portion (55) of the conventional mold (51) is a part of the flat resin passage (56), and the extruded resin is fed to each branch passage in the final stage. Immediately after leaving (54), it was flat. For this reason, there is a problem that it is difficult to develop the width direction end portion only by this development portion (55), and the difference in flow rate balance in the width direction cannot be eliminated. Therefore, in the present invention, a pair of branch portions (manifolds) (9) whose passage width is gradually narrowed are provided so as to be connected to the outlet side end portion of each branch passage (4) in the final stage, By passing through the branch portion (9) to reach the flat resin passage (6), the flow rate balance difference in the width direction is eliminated.

  The effect of providing a pair of branch portions (manifolds) (9) is shown in FIG. FIG. 4 shows the result of comparing the flow rate ratio between the wide plate resin extrusion mold (1) of the present invention and the wide plate resin extrusion mold (51) shown in FIG. .

  The vertical axis in the figure represents the flow rate ratio, and the horizontal axis corresponds to each part of the extrusion mold shown in the upper part of the figure. The flow rate ratio is calculated from the flow rate at each location / the average flow rate of the whole. According to this, in the comparative example shown in FIG. 5, the flow rate balance difference is 1.8%, and the difference is recognized although it is relatively small. On the other hand, according to the extrusion die (1) of the present invention, it is extremely small as 0.7%. These numerical values are calculated, but the actual variation tends to be larger (about 3 to 10 times) than the calculated variation, as in the extrusion die (1) of the present invention. By making it as very small as 0.7%, it becomes possible to make the actual variation extremely small.

  Note that the mold (51) shown in FIG. 5 is not a conventional product itself, but a comparative example for examining the effect of the presence or absence of a manifold. The mold (1) of the present invention also has the following points. This is different from that shown in Patent Document 1.

  In the prior art, the angle formed by the upstream portion of each branch passage and the resin inlet passage or the upstream branch passage and the angle formed by the upstream portion and the downstream portion are both perpendicular, and the resin inlet After the resin is introduced from the passage in the extrusion direction, the resin is flown in the width direction orthogonal thereto, and then the resin is flowed again in the extrusion direction, and the resin is not sent in an oblique direction. It was. In this invention, the angle formed between the upstream portion (3a) (4a) of each branch passage (3) (4) and the resin inlet passage (2) or the upstream branch passage (3) and the upstream portion (3a ) (4a) and the downstream portion (3b) (4b) are both obtuse, the upstream portion (3a) (4a) of each branch passage (3) (4), The resin is sent in a direction oblique to the extrusion direction and the width direction orthogonal thereto. In this way, by making the portion that has conventionally been a right angle an obtuse angle, the flow of the resin becomes smooth and the back pressure can be further reduced.

  In addition, in the conventional one, the angle formed by the upstream portion of each branch passage and the resin inlet passage or the upstream branch passage and the angle formed by the upstream portion and the downstream portion are both perpendicular, The abutting portions of the wall surfaces forming the upstream portion of each branch passage are continuous in the width direction. In contrast, in the present invention, the angle formed between the upstream portion (3a) (4a) of each branch passage (3) (4) and the resin inlet passage (2) or the upstream branch passage (3) and upstream The angles formed by the side portions (3a) (4a) and the downstream portions (3b) (4b) are both obtuse, so that the upstream portions (3a) (4a) of each branch passage (3) (4) ) Of the wall surface forming the upper portion (3a) and (4a) (in other words, the intersection point of the extension line of the wall surface forming the upstream portion (3a) (4a)) Butt portions (P1) (P2) are provided so as to be located further upstream than Q1) and (Q2). Thereby, it becomes possible to further reduce the back pressure.

  In the above, the branch passages (3) and (4) are provided only up to the second stage, but a total of eight third stage branches branched from the respective second stage branch paths (4). You may make it provide a channel | path further and provide the expansion | deployment part of the said structure in the downstream of the 3rd step | paragraph branch passage.

(1) Mold for extrusion of wide plate resin
(2) Resin inlet passage
(3) First-stage branch passage (branch resin passage)
(3a) Upstream part
(3b) Downstream part
(4) Second stage (final stage) branch passage (branch resin passage)
(4a) Upstream part
(4b) Downstream part
(5) Development department
(6) Flat resin passage
(7) Resin outlet
(9) Branch
(P1) (P2) Butting part
(Q1) (Q2) Intersection of extension lines

Claims (3)

A resin inlet passage, a branch resin passage that is connected to the resin inlet passage and includes a plurality of stages of branch passages, a flat resin passage that is continuous to the resin outlet, and an outlet side end portion of each branch passage in the final stage of the branch resin passage. In the mold for extruding a wide plate-shaped resin having an expanded portion that reaches the flat resin passage while expanding the width,
Each development portion is provided with a pair of branch portions that are continuous with the outlet side end portion of each branch passage in the final stage, and that are deeper than the flat resin passage and gradually narrow in the passage width and continue to the flat resin passage. A mold for extruding a wide plate-like resin.   Each branch passage includes an upstream portion connected to the resin inlet passage or the upstream branch passage, and a downstream portion that is bent with respect to the upstream portion and extends in the resin extrusion direction, and the upstream portion and the resin inlet passage or 2. The wide plate-like resin extrusion mold according to claim 1, wherein an angle formed by the upstream branch passage and an angle formed by the upstream portion and the downstream portion are both obtuse.   3. The wide plate according to claim 2, wherein a butt portion of the wall surface forming the upstream portion of each branch passage is located upstream of the intersection of the extension lines of the wall surface forming the upstream portion. Mold for extrusion of plastic resin.

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