Leaf disc filter retainer

Abstract

To provide a porous metal plate which can exert the effects of low pressure loss, high strength and high pressure resistance when used as a retainer for a filter, and can also be used for a wide variety of purposes other than the retainer for the filter.SOLUTION: In a porous metal plate 1, a plurality of through-hole rows L, in which a plurality of through-holes 2 assuming a polygonal shape in a plan view are arranged in one direction in a plate surface of a metallic plate, are arranged in parallel in another direction orthogonal to the one direction. Each through-hole is surrounded by a polygonal annular body 5 made of a narrow belt-like outer peripheral frame 6. Each side of the outer peripheral frame constituting the polygonal annular body is shared by corresponding one side of another polygonal annular body adjacent to it.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a perforated metal plate and a filter retainer. [Background technology]

[0002] Optical films used in liquid crystal displays and the like are produced by melt extrusion. In the melt extrusion method, a thermoplastic resin such as a polymer molten by an extruder is fed to a filtration device to remove impurities, and then extruded from a die into a film shape. The molten resin extruded from the extruder may contain foreign matter that has not been fully melted, burnt and solidified foreign matter, and other foreign matter that may remain or become mixed in. This makes it necessary to remove the impurities by filtration. A leaf disc filter device is known as one such filtering device. The leaf disc filter device disclosed in Patent Document 1 is equipped with a filter element having a donut-shaped retainer made of wire mesh for supporting the filter medium, and a disk-shaped filter medium made of a sintered body of metal fibers or the like arranged on both sides of the retainer via a perforated support plate (e.g., punched metal). Such filter elements are stacked around a polymer discharge pipe (center pole) having a polymer introduction hole on the outer circumferential surface by using a central hub ring to form a filter device.

[0003] The filter elements are sealed in a housing, and molten resin is supplied into the housing at a relatively high pressure. The molten resin that flows between the stacked filter elements passes through the filter medium and is filtered, then passes through the porous support plate to the retainer, where it flows in the inner diameter direction within the gaps in the wire mesh that constitutes the retainer and is collected in the center of the stacked filter elements, and the filtered fluid is sent to a specified destination via a polymer discharge pipe. If the pressure drop inside a leaf disc filter is high, the flow rate of the molten resin passing through it will become uneven, resulting in retention of the resin. Therefore, reducing pressure drop is an important factor that determines the quality of the product. In addition to the filtering resistance of the filter media, the resistance of the molten resin that passes through the filter media to the inside diameter of the retainer, passing through the porous support plate, and then reaching the hub ring, increases as the resin passes through the filter media and flows inward. In particular, in the case of a retainer made of wire mesh, the flow path is a non-linear, complex, and narrow route, so there is a limit to how much pressure loss can be reduced in the retainer, and retention in the retainer is likely to occur.

[0004] Patent Document 2 discloses a retainer for a leaf disc filter having a structure other than a wire mesh, in which a pair of etched discs having a large number of through holes formed by chemical etching arranged in a circumferential direction are joined to each other with the positions of corresponding through holes aligned, and an internal passage extending radially is formed between the pair of etched discs.

[0005] However, because the retainer is made up of two etched disks, there are problems with the number of parts and the thickness. In addition, the thickness dimension of the internal passage formed between the two etched disks is narrowed, which causes an increase in the passage resistance. In addition, the half-etched annular region located between the through holes also increases the passage resistance and reduces quality due to non-uniform residence time. Patent Document 3 discloses a filter support plate (retainer) in which a standing piece part is formed by twisting 90 degrees with respect to the plate surface of a disk-shaped flat plate member and protruding in the vertical direction. However, since the standing piece part located at the outermost periphery cannot be extended to the outer peripheral edge of the disk-shaped flat plate member, the molten resin that has entered through the outermost periphery of the filter medium tends to remain at the outermost peripheral edge (plate surface part) of the disk-shaped flat plate member. In addition, since the plate-shaped part of the flat plate member remains between the standing pieces, this part acts as a resistance to the flow of the molten resin.

[0006] Patent Document 4 also discloses a configuration in which grooves extending in the radial direction are formed on a support / drainage plate serving as a retainer made of a single metal plate, but these grooves end just before the outermost peripheral edge of the support / drainage plate, so there is a problem that the molten resin that has passed through the filter material accumulates in the groove-free portion. Also, the plate-shaped portion without the grooves acts as a resistance to the flow of the molten resin. Such defects are not limited to optical films and optical sheets, and are problems that arise when producing resin molded products, regardless of their applications or shapes. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP2016-185666A [Patent Document 2] JP2009-279517A [Patent Document 3] Japanese Patent Application Publication No. 10-337415 [Patent Document 4] Special Publication No. 6-98250 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above, and provides a perforated metal plate which, when used as a filter retainer, exhibits the effects of low pressure loss, high strength, and high pressure resistance, and which can be used for a variety of purposes other than as a filter retainer. [Means for solving the problem]

[0009] In order to solve the above problems, the perforated metal plate of the present invention is a perforated metal plate having a plurality of through holes, each of which is polygonal in plan view, arranged in one direction on the plate surface of a flat metal plate, and a plurality of rows of through holes arranged in parallel in another direction perpendicular to the one direction, wherein each of the through holes is surrounded by a polygonal ring-shaped body consisting of a narrow band-shaped outer frame, and each side of the outer frame constituting the polygonal ring-shaped body is shared with a corresponding side of another adjacent polygonal ring-shaped body. Effect of the Invention

[0010] According to the present invention, it is possible to provide a perforated metal plate which exhibits the effects of low pressure loss, high strength and high pressure resistance when used as a filter retainer, and which is also suitable for a variety of uses other than as a filter retainer. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view (photograph) of a three-dimensional porous metal plate according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view (photograph) of the same porous metal plate. [Diagram 3] FIG. 2 is a plan view of a model that typically reproduces the flat state of the porous metal plate before it is three-dimensionally processed. [Figure 4] 4(a), (b), and (c) are a front view (a view of the flow path F1 viewed from the outer periphery on the front side), a plan view, and a left side view showing a three-dimensional model of the flat porous metal plate in FIG. [Diagram 5] FIG. [Figure 6] 13(a), (b), and (c) are plan views of a three-dimensional model of a porous metal plate, and explanatory views showing the flow paths F2 and F3 as viewed from the outer periphery side. [Figure 7] 13(a), (b) and (c) are a front view (a view showing the internal state of a first flow path F1), a plan view and a left side view of a three-dimensional porous metal plate according to a second embodiment. [Figure 8] FIG. [Figure 9]13(a), (b), and (c) are plan views of a three-dimensional model of a porous metal plate, and explanatory views showing the flow paths F2 and F3 as viewed from the outer periphery side. [Figure 10] FIG. 11 is a plan view of a model that typically reproduces a flat plate-like state (porous metal plate 30) before the perforated metal plate 40 according to the third embodiment of the present invention is three-dimensionally processed. [Figure 11] 11(a), (b), and (c) are a front view, a plan view, and a right side view showing a porous metal plate 40 which is a three-dimensional version of the flat porous metal plate 30 in FIG. [Figure 12] FIG. 4 is a perspective view of a three-dimensional porous metal plate 40. [Figure 13] 1(a), (b), and (c) are plan views of the porous metal plate 40, and explanatory views showing the flow paths F3 and F4 as viewed from the outer periphery side. [Figure 14] 13(a) and 13(b) are a perspective view (photograph) and a partially enlarged plan view (photograph) showing a configuration example in which a perforated metal plate according to a fourth embodiment is used as a retainer. [Figure 15] FIG. 11 is an enlarged view showing a main configuration of a porous metal plate according to a fourth embodiment. [Figure 16] 13(a), (b), and (c) are an external perspective view, a plan view of a main portion, and a cross-sectional view taken along line AA of an example of a porous metal plate 50 according to a fifth embodiment. [Figure 17] 13(a), (b), and (c) are an external perspective view, a plan view of a main portion, and a BB cross-sectional view of another example of the porous metal plate 50 according to the fifth embodiment. [Figure 18] 1(a) and 1(b) are a front vertical sectional view and a partially enlarged view of a leaf disc filter using a perforated metal plate 20 (1, 30, 40) of the present invention as a retainer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. [First embodiment] Fig. 1 is a plan view (photograph) of a three-dimensional porous metal plate according to the first embodiment of the present invention, and Fig. 2 is a perspective view (photograph) of the same porous metal plate. Fig. 3 is a plan view of a model that typically reproduces the flat state of the same porous metal plate before it is three-dimensionally processed, Fig. 4(a), (b) and (c) are a front view (a view of the flow path F1 viewed from the front outer periphery), a plan view and a left side view showing the three-dimensional state of the flat porous metal plate model of Fig. 3, Fig. 5 is a perspective view of the same porous metal plate, and Fig. 6(a), (b) and (c) are explanatory views showing the plan view of the three-dimensional porous metal plate model, and the state of each flow path F2 and F3 viewed from the outer periphery side.

[0013] The three-dimensionally shaped porous metal plate 20 according to this embodiment can be used as a retainer for supporting two pieces of filter media in a leaf disc filter, and is made of a stainless steel (SUS 304) plate having a thickness of 1 to 6 mm. The porous metal plate 20 can be formed by pressing a flat plate in one go, but can also be manufactured by casting or using a 3D printer.

[0014] As will be described later, the dimensions of the retainer shown in Fig. 1 are merely an example. Also, the size and shape of each polygonal ring 5 constituting one porous metal plate do not need to be completely identical, and errors and deformations in the order of μm or mm are acceptable. The filter material is made of stainless steel in the form of a nonwoven fabric or felt, so it has low strength and hardness. In addition, since the retainer has an uneven surface, a porous support plate (such as a punching plate) is interposed between the retainer and the filter material, which is a flat plate with holes perforated at a specified pitch, in order to hold the sheet-like filter material while maintaining a specified shape.

[0015] The retainer not only needs to be strong enough to support the filter medium and not collapse under pressure, but also needs to have a low-resistance flow path within it that allows the molten resin that has passed through the filter medium to move inward with minimal pressure loss.

[0016] By pressing the flat porous metal plate 1 shown in FIG. 3, it is possible to form the three-dimensional porous metal plate 20 shown in FIGS. 1, 2, 4, and 5, which can be used as a retainer. In addition, Figure 3 shows a configuration in which a vertical through hole row (through hole row) L consisting of four through holes 2 and a vertical through hole row L consisting of three through holes 2 arranged in five rows horizontally, but this only shows a portion of the perforated metal plate 20. In actual manufacturing, a single flat metal plate before the formation of through holes is pressed using a press die, so that punching into the shape having through holes as shown in Fig. 3 and processing into the three-dimensional shape as shown in Fig. 1, Fig. 2, Fig. 4, and Fig. 5 can be carried out in one go. However, for ease of understanding, this example describes a case in which an unperforated metal plate is pressed to form a perforated metal plate 1 having the through holes punched out as shown in Fig. 3, and then processing into the three-dimensional shape as shown in Fig. 1, Fig. 2, Fig. 4, and Fig. 5 is carried out.

[0017] Figures 1 and 2 show a perforated metal plate formed into a fan shape, but when actually used as a retainer for a leaf disc filter, it is formed as a single piece in a doughnut plate shape, so the fan-shaped perforated metal plate shown is only a part of the entire retainer.

[0018] The perforated metal plate 1 before three-dimensional processing shown in Figure 3 has a configuration in which a plurality of through holes 2 (maximum diameter approximately 10 mm) of approximately the same and / or similar shape, which are (regular) polygons when viewed in a plane, are arranged on the surface of a single flat metal plate, and vertical through hole rows L are arranged at a regular pitch in the vertical direction, and are arranged in parallel (parallel) in multiple rows in the horizontal direction with the vertical positions shifted alternately.

[0019] Each through-hole 2 is surrounded by a polygonal ring-shaped body 5 consisting of a narrow band-shaped outer peripheral frame (frame body) 6. Each side 6a, 6b, 6c, 6d, 6e, 6f of the outer peripheral frame 6 constituting the polygonal ring-shaped body 5 is shared (shared) with a corresponding side 6d, 6e, 6f, 6a, 6b, 6c of another adjacent polygonal ring-shaped body 5. Naturally, the polygonal ring-shaped body 5 located on the outer peripheral edge of the perforated metal plate 1 does not share all of its sides with other polygonal ring-shaped bodies because there are no other polygonal ring-shaped bodies 5 adjacent in the outward direction.

[0020] In other words, the perforated metal plate 1 has a configuration in which a plurality of polygonal rings 5 ​​having approximately the same and / or similar shapes, which are regular polygons when viewed in a plane, are arranged in a vertical ring-shaped body row L at a regular pitch in the vertical direction, and the vertical positions of the vertical ring-shaped bodies are alternately shifted in a horizontal direction to form a parallel arrangement.

[0021] The polygonal ring 5 is preferably a polygon having an even number of corners (sides), such as a square, hexagon, or octagon, but may be a polygon having an odd number of corners. Alternatively, the length of each side of a polygonal ring does not need to be strictly constant, and some error is within the allowable range. In other words, each polygonal ring may have approximately the same shape or approximately similar shapes.

[0022] In this example, each polygonal ring 5 is approximately a regular hexagon, and if we focus on the polygonal ring 5A located approximately in the center of Figure 3, the upper side 6a of its outer frame 6 is shared with the lower side 6d of the other polygonal ring 5B located directly above it. Furthermore, the diagonal side 6b diagonally upward to the right of polygonal ring 5A is shared with the diagonal side 6e diagonally downward to the left of another polygonal ring 5C located diagonally upward to the right, the diagonal side 6c diagonally downward to the right of polygonal ring 5A is shared with the diagonal side 6f diagonally upward to the left of another polygonal ring 5D located diagonally downward to the right, the bottom side 6d of polygonal ring 5A is shared with the top side 6a of another polygonal ring 5E located directly below, the diagonal side 6e diagonally downward to the left of polygonal ring 5A is shared with the diagonal side 6b diagonally upward to the right of another polygonal ring 5F located diagonally downward to the left, and the diagonal side 6f diagonally upward to the left of polygonal ring 5A is shared with the diagonal side 6c diagonally downward to the right of another polygonal ring 5G located diagonally upward to the left. In this way, corresponding sides are shared between adjacent polygonal rings 5.

[0023] The six corners of each polygonal ring 5, i.e., the intersections of the six sides 6a-6f, form triangular corner regions 8a-8f. Focusing on polygonal ring 5A, the upper left corner region 8a is shared with the lower left corner of another polygonal ring 5B located directly above, and the right corner of polygonal ring 5G diagonally to the upper left. Furthermore, each of the other corner regions 8b-8f of polygonal ring 5A also shares a corner with the other two adjacent polygonal rings.

[0024] The six corners of each polygonal ring 5, i.e., the portions where the six sides 6a to 6f intersect, are chamfered to form triangular corner regions 8a to 8f, and although the peripheral contour shape of each polygonal ring 5 is not strictly a regular hexagon, it is referred to as a regular hexagon in this specification.

[0025] In this example, both ends of each side in the longitudinal direction are bent so that the corner regions 8a to 8f form an equilateral triangle, but this is only an example, and each side may be bent closer to the front than both ends in the longitudinal direction as in the second embodiment described later. In other words, the position at which each side is bent can be selected arbitrarily. This allows the opening area of ​​the through hole 2 in a plan view to be adjusted.

[0026] The configuration of the three-dimensional porous metal plate 20 shown in Figs. 4 and 5 will be described below with reference to an embodiment in which the plate is made of a hexagonal ring. That is, the porous metal plate 20 has a configuration in which a plurality of through holes 2 of the same shape (or / and similar shape) that is hexagonal in plan view are arranged on the plate surface of a single flat metal plate, and vertical through hole rows L arranged at a regular pitch in the vertical direction (radial direction in FIG. 1) are arranged in multiple rows in the horizontal direction (circumferential direction in FIG. 1) in parallel with alternating vertical position shifts. Each through hole 2 is surrounded by a hexagonal ring-shaped body 5 consisting of a narrow band-like outer peripheral frame 6. The outer peripheral frame 6 constitutes a part of the metal plate. The upper side 6a and the lower side 6d of the hexagonal ring 5 are respectively shared with the lower side 6d and the upper side 6a of another hexagonal ring adjacent in the vertical direction, and the other sides 6b, 6c, 6e, and 6f of the hexagonal ring are respectively shared with the corresponding sides 6e, 6f, 6b, and 6c of another hexagonal ring adjacent in each diagonal direction.

[0027] Furthermore, the six corner regions 8 of each hexagonal ring 5 are arranged such that flat and small-area (triangular) convex apexes 8 protruding toward the front (toward the paper surface) perpendicular to the surface direction of the porous metal plate 20 (porous metal plate 1 shown in FIG. 3) and flat and small-area (triangular) concave bottoms 8 recessed (protruding) toward the back (toward the paper surface) of the porous metal plate are alternately arranged in the circumferential direction. The corner regions 8a, 8c, and 8e of each hexagonal ring are the convex apexes 8, and the other corner regions 8b, 8d, and 8f correspond to the concave bottoms 8. The convex apexes 8 are on the same plane, and the concave bottoms 8 are on the same plane, with both planes being in a parallel positional relationship. Each side 6a-6f connecting the adjacent convex apexes 8 and concave bottoms 8 extends at a predetermined angle θ1 with respect to the surface direction of the perforated metal plate 20 (flat-shaped perforated metal plate 1). The convex apexes 8 when viewed from the planar side of the perforated metal plate 20 become concave bottoms when viewed from the rear side, and the concave bottoms 8 when viewed from the planar side become convex apexes when viewed from the rear side. Each polygonal ring-shaped body 5 has a bilaterally symmetrical shape when viewed from the planar side or the rear side. Since the illustrated perforated metal plate 20 is merely a model, the boundaries between each corner region 8 and each side 6a to 6f are bent at an obtuse angle, but when actually manufacturing a perforated metal plate by press processing, casting, or a 3D printer, the boundaries may have a curved shape rather than a bent shape.

[0028] Each flat convex top 8 convex and each concave bottom 8 concave are means for contacting and supporting a flat porous support plate (indicated by reference numeral 106 in FIG. 18) interposed between the filter medium and the retainer. Therefore, if the interval G1 between adjacent convex tops 8 convex and the interval G2 between adjacent concave bottoms 8 concave are too wide, the porous support plate portion located between the convex tops 8 convex and the porous support plate portion located between the concave bottoms 8 concave are likely to fall toward the retainer side due to the pressure from the molten resin and to be curved. When each porous support plate portion is curved, the filter medium supported by the porous support plate is curved accordingly, making it difficult to maintain a flat posture necessary for maintaining proper filtration performance, which causes a decrease in filtration performance.

[0029] Furthermore, if the opening area of ​​the through hole 2, i.e., the distance G1 between two adjacent convex tops 8 convex and the distance G2 between two adjacent concave bottoms 8 concave, is too narrow, this will result in an increase in resistance to the flow of molten resin that has entered the retainer through the filter medium and porous support plate within the retainer. In other words, by appropriately setting the distance G1 between adjacent convex tops 8 and the distance G2 between adjacent concave bottoms 8, it is possible to appropriately achieve both resistance to the molten resin as a filtration fluid and the ability to maintain the position of the porous support plate. Furthermore, according to the configuration of the present invention, the individual polygonal rings can be constructed with high dimensional accuracy and regularly arranged, making it possible to maintain the distances G1 and G2 constant.

[0030] The perforated metal plate 20 of the present invention can be manufactured by pressing, casting, or using a 3D printer, so that dimensional accuracy can be ensured. Moreover, since it is manufactured from a high-strength metal such as stainless steel with a sufficient thickness to provide sufficient strength, it will not be crushed or deformed even under high pressure, and the above-mentioned gaps G1 and G2 can be maintained at an optimum value, so that the resistance to the passage of molten resin can be maintained at a constant low value.

[0031] The outer peripheral frame 6 (each side 6a to 6f) connecting each of the convex apexes 8 and each of the concave bottoms 8 extends at a constant angle θ1 with respect to the surface direction of the perforated metal plate. By changing the inclination angle θ1 of each side for each perforated metal plate, the thickness of the perforated metal plate and the opening area of ​​the through hole 2 in plan view (the interval G1 between the convex apexes 8 and the interval G2 between the concave bottoms 8) can be changed. As described above, if the opening area of ​​the through hole 2 in plan view is too large or too small, it will cause problems, but according to the present invention, by setting the angle θ1 constant, it is possible to uniquely set the opening area of ​​the through hole 2 in plan view.

[0032] By applying the porous metal plate 20 of this embodiment to a retainer of a leaf disc filter, in addition to the first flow path F1 along the vertical through-hole row L, a second flow path F2 and a third flow path F3 that intersect with the first flow path at an angle shifted by 60 degrees are formed (FIGS. 4 and 5). The first flow path F1 is a straight flow path extending in the radial (inner diameter) direction in FIG. 1 and FIG. 2, and the second and third flow paths F2 and F3 are straight flow paths (flow paths toward the inner diameter portion) that intersect with it at 60 degrees.

[0033] Each of the flow paths F1, F2, and F3 is formed linearly along the upper and lower sides of the inclined sides 6a to 6f. That is, the route along which the molten resin flows in the inner diameter direction (including the radial direction and other directions toward the inner diameter portion) is a linear route formed on the upper side of each of the inclined sides 6a to 6f located in each of the flow paths F1, F2, and F3, and a linear route formed on the lower side of each of the sides 6a to 6f. Since the number of non-linear routes that zigzag up and down and left and right due to the presence of obstacles is reduced, the resistance when the molten resin passes through can be reduced, and pressure loss can be reduced. Therefore, it is possible to prevent the non-uniformity of the flow rate of the molten resin and the resulting retention, thereby maintaining the quality of the product.

[0034] In addition, as is clear from Fig. 4(a) and Fig. 6(b)(c) showing the internal state of each flow path F1, F2, F3, adjacent through holes 2 communicate with each other through spaces (flow paths) formed above and below each side 6a-6f by linear routes (flow paths) with little vertical displacement and uniform width over the entire length, so that the passage resistance of the molten resin passing between the polygonal rings can be significantly reduced. From these figures, it is clear that there are almost no obstacles inside each flow path F1, F2, F3, and a linear route with a uniform width and a determined path is formed. In other words, according to the present invention, by forming each flow path F1, F2, F3 toward the inner diameter part without variation in the path, the directionality of the flow path of the molten resin can be improved, and the molten resin can be efficiently flowed to the inner diameter part by each flow path F1, F2, F3.

[0035] Note that flow path F1 is a flow path along a substantially radial direction, whereas flow paths F2 and F3 intersect with the radial direction. However, as will be described later with reference to FIG. 15, the filtered molten resin can be made to flow to a discharge pipe located in the inner diameter portion via a hole provided in the hub. More specifically, as is clear from Figs. 1 and 2, the first flow path F1 forms a flow path with few obstacles that penetrates linearly from the outermost periphery to the innermost periphery of the doughnut-shaped porous metal plate 20. Therefore, the molten resin that has flowed into the first flow path F1 through the filter material can be efficiently made to flow to the discharge pipe located in the inner diameter part. In particular, the molten resin that has flowed into the outermost periphery of the porous metal plate and is likely to remain can be stably made to flow to the inner diameter part. In addition, the second flow path F2 and the third flow path F3 have their inner diameter side terminals connected to the discharge pipe at the inner diameter part of the porous metal plate 20 or connected to the first flow path F1 on the way, so that the molten resin that has flowed into the second and third flow paths is efficiently discharged through the flow path F1 of the first flow path.

[0036] In a leaf disc filter, it is necessary to ensure the flow of molten resin in the radial direction between the filter media (retainer portion) and toward the inner diameter portion, but in a retainer made of wire mesh, the flow direction is prone to vary not only toward the inner diameter portion but also up, down, left, and right. In contrast, in this embodiment, the flow direction can be concentrated in the direction toward the inner diameter portion.

[0037] In particular, when filtering high-viscosity fluids such as molten polymers, the pressure loss in the filter material increases and the pressure difference before and after the filter material also increases, so the retainer placed in the passage of the molten resin is required to have performance such as low pressure loss, high pressure resistance, and high bending strength. However, the porous metal plate 20, which is made of a structure in which polygonal rings with a simple shape are connected vertically and horizontally, has almost no obstructing parts in each of the molten resin flow paths F1, F2, F3, and is therefore able to fully meet these requirements (low pressure loss, high pressure resistance, high bending strength).

[0038] In the case of a retainer made of wire mesh or the like, the retainer itself cannot be expected to have sufficient strength to hold the filter medium, so the majority of the filter medium's holding strength is mainly dependent on the porous support plate. In contrast, the porous metal plate 20 of the present invention has high mechanical strength, so as long as the opening area of ​​the through holes 2 is maintained at an appropriate value, the filter medium's holding strength by the retainer can be increased and the dependency on the porous support plate can be reduced. As a result, the porous support plate can be made thinner or even omitted. This allows the entire leaf disc filter to be made thinner, and the number of filter elements incorporated can be increased to increase the filtration area.

[0039] In addition, in the perforated metal plate 20 shown in Figures 1 and 2, the numbers indicating the dimensions of the retainer shown in the figures (overall diameter 288 mm, inner diameter φ97 mm, outer diameter dimension of the polygonal ring portion 95.5 mm, etc.) are merely examples. When the porous metal plate 20 is designed as a retainer for a leaf disc filter, flexible response is possible by previously adjusting the number and opening area of ​​the through holes 2 according to the pressure applied during filtration. In the illustrated and described embodiment, a retainer made of one perforated metal plate 20 is shown, but two or more perforated metal plates 20 stacked and integrated together can also be used as the retainer. In this case, this multi-layered retainer can also be manufactured by a manufacturing method using a 3D printer using inkjet printing technology or the like, a casting method in which molten metal is poured into a mold to form the retainer 1, or a manufacturing method using powder metallurgy in which metal powder is molded using a die and sintered. In the casting method and powder metallurgy, a mold is manufactured using a retainer 1 that has been manufactured in advance, and mass production can be performed using this mold, thereby increasing productivity. This also applies to the manufacturing methods of the retainers 30 according to the second, third, and fourth embodiments described below.

[0040] [Second embodiment] Next, Fig. 7(a), (b) and (c) are a front view (a view showing the internal state of the first flow path F1), a plan view and a left side view of a three-dimensional porous metal plate according to the second embodiment, and Fig. 8 is a perspective view of the same porous metal plate. Also, Fig. 9(a), (b) and (c) are a plan view of a model of a three-dimensional porous metal plate, and an explanatory diagram showing the state in which each of the flow paths F2 and F3 is viewed from the outer periphery side. In addition, the same parts as those of the perforated metal plate 20 according to the first embodiment shown in Figs. 1, 2, 4 and 5 are denoted by the same reference numerals.

[0041] This porous metal plate 20 is similar to the porous metal plate 20 according to the first embodiment in that the flat porous metal plate 1 in FIG. 3 is formed into a three-dimensional shape consisting of a plurality of polygonal ring-shaped bodies by pressing or the like. However, by varying the positions at which the sides 6a to 6f are bent (curved), the opening area of ​​each through hole 2 in a planar view is narrowed.

[0042] That is, in the first embodiment, the corner regions 8a-8f are formed in an equilateral triangle shape, so that the positions at which both ends of each side 6a-6f are bent coincide with one side 8S of each corner region 8a-8f. In contrast, in the second embodiment, a position shifted toward each side 6a-6f from each side 8S of the corner regions 8a-8f is set as a bending line (bending position) 25, and both ends of each side 6a-6f are bent along this bending line 25. Therefore, the angle θ2 between each side 6a-6f and the surface direction of the porous metal plate 20 is larger than the angle θ1 in the first embodiment. As described above, the boundaries between the corner regions 8a to 8f and the corner regions 6a to 6f may be curved surfaces.

[0043] In this way, by adjusting the positions at which each side 6a to 6f is bent (curved) along the longitudinal direction of each side, the opening area of ​​each through hole 2 can be changed, and the interval G1 between adjacent convex tops 8 and the interval G2 between adjacent concave bottoms 8 can be changed. As described above, when the opening area of ​​the through hole is increased, the intervals G1 and G2 between the corner regions are widened, making it easier for the porous support plate to bend and deform, while the resistance to the passage of molten resin can be reduced. Conversely, when the opening area of ​​the through hole is reduced, the intervals G1 and G2 between the corner regions are narrowed, making it harder for the porous support plate to bend and deform, while the resistance to the passage of molten resin increases. According to the present invention, it is possible to adjust the opening area of ​​the through hole and the intervals G1 and G2 between the corner regions to any value simply by changing the positions at which each side 6a to 6f is bent.

[0044] Even in the porous metal plate 20 according to the second embodiment, as shown in Figures 7(a) and 9(b) and (c), each flow path F1, F2, F3 is in a state in which each through hole 2 is connected by a linear flow path via the space formed above and below each side 6a to 6f, thereby significantly reducing the resistance to the passage of the molten resin. The diameters and shapes of the polygonal rings 5 ​​constituting one perforated metal plate 20 do not need to be strictly the same, and the polygonal rings may be similar in shape or may vary in shape depending on the shape of the product to which the perforated metal plate is applied. In actual manufacturing, it may be difficult to make the polygonal rings strictly the same shape and size, and errors and deformations of the order of microns or mm do not cause performance problems. For example, polygonal rings with different diameters (through hole sizes) may be mixed in one three-dimensional porous metal plate. That is, when forming a donut plate-shaped retainer, the polygonal rings located on the inner diameter side may be configured to have a smaller diameter than the polygonal rings located on the outer diameter side. Alternatively, the polygonal rings may be configured so that the diameters of the polygonal rings gradually increase from the inner diameter side to the outer diameter side. The actions and effects of the second embodiment are similar to those of the first embodiment. Also, two or more perforated metal plates 20 may be stacked and integrated together to be used as a retainer.

[0045] [Third embodiment] Next, Fig. 10 is a plan view of a model that typically reproduces a flat state (porous metal plate 30) before the porous metal plate 40 according to the third embodiment of the present invention is three-dimensionally processed, and Figs. 11(a), (b), and (c) are a front view, a plan view, and a right side view showing the porous metal plate 40 obtained by three-dimensionally processing the flat porous metal plate 30 in Fig. 10. Fig. 12 is a perspective view of the three-dimensional porous metal plate 40, and Figs. 13(a), (b), and (c) are explanatory views showing a plan view of the porous metal plate 40 and the flow paths F3 and F4 viewed from the outer periphery side. The configuration, action, and effect of the flat perforated metal plate 30 in this embodiment and the perforated metal plate 40 after three-dimensional processing are the same as those of the first and second embodiments, except that the polygonal ring-shaped body 5 is rectangular, so only the differences will be described.

[0046] The perforated metal plate 30 before three-dimensional processing shown in Fig. 10 is configured to have a configuration in which a plurality of through holes 2 having substantially the same shape or / and similar shapes, which are quadrangular (square) in plan view, are arranged in a single flat metal plate at a regular pitch in the vertical direction, and vertical through hole rows L are arranged in parallel in multiple rows in the horizontal direction. Note that Fig. 10 shows a configuration in which five vertical through hole rows L each consisting of five through holes 2 are arranged in five rows horizontally, but this only shows a portion of the perforated metal plate 30.

[0047] Each through hole 2 is surrounded by a rectangular ring-shaped body (polygonal ring-shaped body) 5 consisting of a narrow band-shaped outer peripheral frame (frame body) 6. Each side 6a, 6b, 6c, 6d of the outer peripheral frame 6 constituting the rectangular ring-shaped body 5 is shared (shared) with a corresponding side 6c, 6d, 6a, 6b of another rectangular ring-shaped body 5 adjacent to the top, bottom, left, and right.

[0048] The four corners of each rectangular ring-shaped body 5, that is, the portions where the four sides 6a to 6d intersect, form square corner regions 8a to 8d. In this example, both ends of each side in the longitudinal direction are bent so that the corner regions 8a to 8d are square, but this is only one example, and each side may be bent at a position closer to the center than both ends in the longitudinal direction. In other words, the position at which each side is bent can be selected arbitrarily, and the opening area of ​​the through hole 2 in a plan view can be adjusted accordingly. Also, each of the quadrangular rings 5 ​​may be in another quadrilateral shape, such as a rectangle, a parallelogram, or a rhombus.

[0049] Next, the configuration of the porous metal plate 40 obtained by three-dimensionally processing the flat porous metal plate 30 shown in FIG. 10 will be described with reference to FIGS.

[0050] The porous metal plate 40 has a configuration in which a plurality of through holes 2 of the same shape, which is quadrangular (square in this example) in plan view, are arranged in a single metal plate, and vertical through hole rows L, which are arranged at a regular pitch in the vertical direction (radial direction in FIG. 1), are arranged in parallel in multiple rows in the horizontal direction (approximately the circumferential direction in FIG. 1). Each through hole 2 is surrounded (surrounded) by a rectangular ring-shaped body 5 consisting of a narrow band-like outer peripheral frame 6, and the upper side 6a and lower side 6c of the rectangular ring-shaped body 5 are respectively shared with the lower side 6c and upper side 6a of another rectangular ring-shaped body adjacent in the vertical direction, and the left and right sides 6b, 6d of the rectangular ring-shaped body are respectively shared with the corresponding sides 6d, 6b of another rectangular ring-shaped body adjacent in the left and right horizontal directions. Furthermore, in the four corner regions 8 of each rectangular ring-shaped body 5, flat and small-area (square-shaped) convex apexes 8 protruding toward the front direction perpendicular to the surface direction of the perforated metal plate 40 (perforated metal plate 30 shown in FIG. 10) and flat and small-area (square-shaped) concave bottoms 8 retreating toward the back direction of the perforated metal plate are alternately arranged in the circumferential direction. The convex apexes 8 are on the same plane, and the concave bottoms 8 are on the same plane, and both planes are in a parallel positional relationship. Each side 6a to 6d connecting the adjacent convex apexes 8 and the concave bottoms 8 extends at a predetermined angle θ3 inclined with respect to the surface direction of the perforated metal plate 40 (30). The convex apexes 8 convex when viewed from the planar side of the perforated metal plate 40 become concave bottoms when viewed from the rear side, and the concave bottoms 8 concave when viewed from the planar side become convex apexes when viewed from the rear side. Moreover, each polygonal ring body 5 has a bilaterally symmetrical shape when viewed from above or from behind.

[0051] Focusing on the polygonal ring 5H in the center of Fig. 11(b), the corner region 8a in the upper left corner and the corner region 8c diagonally opposite it are convex apexes 8convex, and the corner region 8b in the upper right corner and the corner region 8d diagonally opposite it are concave bottoms 8concave. In addition, in the polygonal ring 5I directly above the polygonal ring 5H, the corner region 8a in the upper left corner and the corner region 8c diagonally opposite it are concave bottoms 8concave, and the corner region 8b in the upper right corner and the corner region 8d diagonally opposite it are convex apexes 8convex. Furthermore, in the polygonal ring 5J on the right side of the polygonal ring 5H, the corner region 8a in the upper left corner and the corner region 8c diagonally opposite it are concave bottoms 8concave, and the corner region 8b in the upper right corner and the corner region 8d diagonally opposite it are convex apexes 8convex. The polygonal ring 5K below the polygonal ring 5H and the polygonal ring 5L on the left side have the same circumferential arrangement of the convex apexes 8 convex and the concave bottoms 8 concave as the polygonal ring 5J. When viewed from the center of one polygonal ring 5H, the circumferential arrangements of the convex apexes 8 convex and the concave bottoms 8 concave in each of the polygonal rings 5I, 5J, 5K, and 5L located above, below, left and right are the same and are reversed from the arrangement in the polygonal ring H.

[0052] The arrangement of the convex apexes 8 convex and the concave bottoms 8 concave in the other polygonal rings located diagonally above and below the polygonal ring 5H is the same as that of the polygonal ring 5H. Each convex top 8 convex and each concave bottom 8 concave, which are flat surfaces, are means for contacting and supporting the flat porous support plate interposed between the filter medium and the retainer. The effects of the spacing G1 between the convex tops 8 convex and the spacing G2 between the adjacent concave bottoms 8 concave on the flatness of the porous support plate and the effects on the passage resistance of molten resin are the same as those described in the first embodiment, so duplicated descriptions will be omitted.

[0053] As in the first embodiment, the perforated metal plate 40 of this embodiment can be manufactured by pressing, casting, or using a 3D printer, so that dimensional accuracy can be ensured. Moreover, since it is manufactured from a high-strength metal such as stainless steel, it will not be crushed or deformed even under high pressure, and the above-mentioned gaps G1 and G2 can be maintained at an optimum level, so that the resistance to the passage of the molten resin can be maintained constant. The peripheral frame 6 (each side 6a to 6d) connecting each convex top 8 and each concave bottom 8 extends at a constant angle θ3 with respect to the surface direction of the porous metal plate. The advantages of changing the inclination angle θ3 of each side for each porous metal plate are the same as in the first embodiment, so a duplicated explanation will be omitted.

[0054] By applying the porous metal plate 40 of this embodiment to a donut-shaped retainer used in a leaf disc filter, in addition to the first flow passage F1 along the vertical through-hole row L, a second flow passage F2 intersecting (orthogonal to) the first flow passage is formed. In the donut-shaped retainer shown in Figures 1 and 2, the first flow passage F1 is a linear flow passage extending in the radial (inner diameter) direction, and the second flow passage F2 is a linear flow passage intersecting the first flow passage F1. Each of the flow passages F1 and F2 is formed linearly along the upper and lower sides 6a to 6d of the inclined sides. In other words, the route through which the molten resin flows in the inner diameter direction (radial direction, other direction toward the inner diameter portion) and other directions is a straight route of uniform width formed on the upper side of each of the inclined sides 6a-6d located in each of the flow paths F1 and F2, and a straight route of uniform width formed on the lower side of each of the sides 6a-6d, and the number of non-linear routes that zigzag up and down and left and right is reduced, so that the resistance when the molten resin passes through can be reduced and pressure loss can be reduced. Therefore, it is possible to prevent unevenness in the flow rate of the molten resin and the resulting retention, thereby maintaining the quality of the product.

[0055] In this way, adjacent through holes 2 are connected to each other via the spaces formed above and below each side 6a to 6d, by vertical displacement and linear routes of uniform width (flow paths F1, F2), so that the molten resin that passes through the upper and lower filter media and flows into the retainer experiences significantly reduced resistance to flow when it flows between the polygonal rings. In addition to the first and second flow paths F1 and F2, third and fourth flow paths F3 and F4 are formed extending in the diagonal direction of each polygonal ring 5. The third and fourth flow paths F3 and F4 are formed along the concave bottoms 8 arranged in the diagonal direction. The adjacent through holes 2 communicate with each other through a continuous space formed on each concave bottom 8 by a linear route (flow paths F3 and F4) without vertical displacement, so that the passage resistance of the molten resin passing between the polygonal rings can be significantly reduced. When the first flow path F1 is set in a direction along the radial direction of the donut plate-shaped retainer shown in Figures 1 and 2, the filtered molten resin that has flowed into the first flow path F1 is quickly discharged to the discharge pipe in the inner diameter part without stagnation. The molten resin that has flowed into the third and fourth flow paths F3 and F4 is discharged directly to the discharge pipe from the inner diameter side opening, or is discharged to the discharge pipe via the first flow path F1. The molten resin that has flowed into the second flow path F2 is discharged via the first, third or fourth flow path F1, F2 or F3.

[0056] Like the first and second embodiments, the porous metal plate 40 according to this embodiment also satisfies the requirements for high pressure resistance and high bending strength, and can ensure a radial flow of molten resin through each flow path. In the illustrated and described embodiment, a retainer made of one perforated metal plate 40 is shown, but a retainer made of two or more perforated metal plates 40 stacked and integrated together can also be used.

[0057] [Fourth embodiment] The flat perforated metal plate 1 shown in FIG. 3 can also be used as a retainer by stacking two perforated metal plates 1 with the positions of the through holes 2 shifted, without machining them three-dimensionally.

[0058] That is, Figures 14(a) and (b) are an oblique view and a partially enlarged plan view (both are photographs) of a retainer made of two stacked perforated metal plates 1, and Figure 15 is a plan view of the main parts showing the positional relationship of the polygonal rings that make up each perforated metal plate.

[0059] As shown in each figure, two porous metal plates 1 are directly stacked in parallel, and the positions of the through holes 2 of each porous metal plate are offset to form a zigzag flow path in the thickness direction. If the quality of the molten resin that flows into the retainer through the filter media arranged on both sides of the retainer is not uniform when filtered by each filter media, the quality of the molten resin finally discharged into the discharge pipe in the inner diameter part may vary. However, the retainer of this embodiment can form regular zigzag flow paths in each polygonal ring portion, so that the molten resin from the filter media located above and below can be mixed and uniformed. If necessary, a spacer (not shown) may be interposed between the two perforated metal plates 1 to form a passage between the two plates.

[0060] In the retainer made of the perforated metal plate 1, the sides 6a to 6f and the corner regions 8a to 8f are flat with no steps except for the through holes 2, so that the perforated support plate made of the punching plate can be supported by a completely flat surface. This makes it possible to prevent the perforated support plate from being deformed by the pressure during filtration. Alternatively, since the perforated metal plate 1 can directly support the filter medium, it is possible to omit the perforated support plate and contribute to making the entire filter element thinner. In the illustrated and described embodiment, the retainer is made up of two perforated metal plates 1, but a retainer made up of three or more perforated metal plates 1 stacked on top of each other can also be used.

[0061] [Fifth embodiment] Figures 16 and 17 are explanatory diagrams of a porous metal plate 50 relating to the fifth embodiment, Figures 16(a) and 17(a) are external perspective views, Figures 16(b) and 17(b) are enlarged plan views of the main parts, and Figures 16(c) and 17(c) are cross-sectional views along the lines AA and BB, respectively. By forming the perforated metal plate 50 into a doughnut plate shape, it can be used as a material for a retainer for a leaf disc filter.

[0062] The perforated metal plate 50 has a configuration in which a column member row L consisting of a plurality of column members 52 arranged in parallel in a line at a predetermined pitch in one direction (vertical direction) on one plane and erected in a posture perpendicular to the plane is arranged at a predetermined pitch in a direction (horizontal direction) perpendicular to the arrangement direction, with each column member position in the one direction being shifted alternately. Furthermore, the plurality of column members arranged closely to form each corner of a polygon are connected by side members 55. The perforated metal plate 50 is made of stainless steel or the like, and can be manufactured by injection molding, a 3D printer, or the like.

[0063] In each of the embodiments of Figures 16 and 17, the individual pillar members 52 are arranged to form a quadrangle, but this is just one example, and they may also be arranged to form a triangle, pentagon, hexagon, or octagon.

[0064] 16, the side members 55 correspond to sides connecting four pillar members 52 forming corners of a quadrangle (square, rectangle, parallelogram, rhombus, etc.), and are made of wire or rod material. The opening area between the four pillar members 52 is kept large to reduce the resistance to the passage of molten resin, while the side members 55 provide reinforcement to increase strength.

[0065] In addition, when the porous metal plate 50 is used as a retainer for a leaf disc filter, the first flow passage F1 becomes a straight flow passage in the inner diameter direction, allowing the molten resin to pass through efficiently with low resistance. The second and third flow passages F2 and F3 intersecting the first flow passage F1 are also straight flow passages in the inner diameter direction with few obstacles.

[0066] In the embodiment of Fig. 17, a large number of column member groups, each consisting of three column members 52 arranged closely together to form a triangle (equilateral triangle, isosceles triangle, etc.) in a plan view, are arranged continuously in the vertical, horizontal and diagonal directions. Furthermore, the three column members 52 at the positions corresponding to the three vertices of the triangle are connected by side members 55. Therefore, the pressure resistance is stronger than that of the embodiment of Fig. 16.

[0067] In addition, when the porous metal plate 50 is used as a retainer for a leaf disc filter, the first flow passage F1 becomes a straight flow passage in the inner diameter direction, allowing the molten resin to pass through efficiently with low resistance. The second and third flow passages F2 and F3 intersecting the first flow passage F1 are also straight flow passages in the inner diameter direction with few obstacles.

[0068] These porous metal plates 50 have flat upper and lower end faces of each pillar member 52, which are arranged along a single plane, so that when used as a leaf disc filter retainer, the porous support plate arranged between the filter medium can be stably supported. In particular, by adjusting the pitch between each pillar member 52, the opening area formed by the four pillar members can be set to an appropriate value, making it possible to appropriately set the support stability of the porous support plate and the passage resistance of molten resin.

[0069] [Application example to leaf disc filters] Next, FIGS. 18(a) and (b) are a front vertical sectional view and a partially enlarged view of a leaf disc filter using the perforated metal plate 20 (1, 30, 40) of the present invention as a retainer.

[0070] The leaf disc filter 100 generally comprises a retainer 102 made of a doughnut-shaped perforated metal plate 20, a hub 104 made of a solid metal material fixed to the center of the retainer, doughnut-shaped punching plates (perforated support plates) 106 arranged on the upper and lower outer surfaces of the retainer 102, with the inner diameter portion welded to the hub 104, doughnut-shaped filter media 108 arranged on the outer surface of each punching plate, rings 110 as annular bodies arranged on both the upper and lower sides of the hub outer periphery and welded to the hub with the inner diameter side outer surface of the filter media 108 sandwiched between the hub, and a spacer 112 arranged on the outer surface of the upper filter media 108 and consisting of a plurality of rod-shaped bodies extending radially from the center like spokes. The outer diameter side ends of the punching plate 106, the filter media 108, and each spacer 112 are fixed by welding.

[0071] The molten resin that has passed through the filter material 108 and punched plate 106 in sequence enters the inside of the retainer 102 from its outer surface, passes through each of the flow paths F1, F2, F3 and other flow paths of the retainer, is collected in the center, and is sent to a discharge pipe (not shown) in the center via a hole provided in the hub.

[0072] A void S is formed between the outer periphery of retainer 102 and the inner wall of the outer periphery of spacer 112, and the molten resin that enters the void from the filter media portion located outside this void S moves through each flow path of retainer 102 toward the inner diameter side inside the retainer and is sent to a discharge pipe (not shown) in the center through a hole provided in the hub. In this way, the molten resin that passes through the filter media can flow toward the inner diameter side through the retainer without stagnation at the outer periphery.

[0073] It is also important that the quality of the molten resin that is filtered by the two filter media 108 and flows into the retainer 102 is uniform. In the perforated metal plate of the present invention, the molten resin that has passed through each filter media in the through hole 2 and each flow path joins together and mixes to become uniform.

[0074] <Summary of the configuration, action, and effects of the present invention> The perforated metal plate 1, 30 according to the first aspect of the present invention has a plurality of through holes 2, each of which is polygonal in plan view, arranged in the plate surface of a flat metal plate, and a plurality of vertical through hole rows L, each of which is arranged in parallel in the horizontal direction, and each through hole is surrounded by a polygonal ring-shaped body 5 consisting of a narrow band-like peripheral frame (frame body) 6. Each side of the peripheral frame 6 constituting the polygonal ring-shaped body is shared with a corresponding side of another adjacent polygonal ring-shaped body. In other words, the perforated metal plates 1, 30 are each configured by arranging a plurality of polygonal rings 5, each of which has a polygonal shape when viewed in a plane, in a vertical direction, and a vertical ring-shaped body row L, which is arranged in parallel in multiple rows in the horizontal direction, and each side of the outer peripheral frame 6 constituting the polygonal rings is shared with a corresponding side of another adjacent polygonal ring.

[0075] The polygon may have an even or odd number of sides, such as a quadrilateral, hexagon, octagon, etc. Also, it does not have to be a regular polygon. Each through hole 2 formed on a single metal plate may have the same shape, similar shapes, or different sizes. The through holes constituting the vertical through hole row L are arranged in a row in the vertical direction (one direction) at a regular pitch. This vertical through hole row is arranged in multiple rows in parallel in the horizontal direction (the other direction perpendicular to the one direction). Depending on the shape of the through hole, for example, if it is hexagonal, it is necessary to arrange the vertical positions of adjacent vertical through hole rows by shifting them. By constructing the perforated metal plate from a metal material with sufficient strength, such as stainless steel, it is possible to suppress deformation due to pressure during filtration, and to increase strength, durability over time, and shape retention. The flat porous metal plate 1 can be used as a structural material for a variety of purposes, such as a filter retainer, by machining each polygonal ring into a three-dimensional shape.

[0076] The second perforated metal plate 20, 30 according to the present invention has a plurality of through holes 2, each of which is a (regular) polygon in plan view, arranged on the surface of a metal plate, and a plurality of rows of vertical through holes, each of which is arranged at a predetermined pitch in the vertical direction, arranged in parallel in the horizontal direction. Each through hole is surrounded by a polygonal ring 5 made of a narrow band-like outer peripheral frame (frame body) 6. Each side of the outer peripheral frame 6 constituting the polygonal ring 5 is shared with a corresponding side of another adjacent polygonal ring. In each corner region 8 of each polygonal ring, a flat and small-area convex apex 8 protruding toward the front direction perpendicular to the surface direction of the perforated metal plate and a flat and small-area concave bottom 8 recessed toward the back direction of the perforated metal plate are alternately arranged in the circumferential direction, and each of the convex apexes and each of the concave bottoms are on the same plane. Each side 6a, 6b, ... of the outer peripheral frame connecting each convex top portion and each concave bottom portion extends at a predetermined angle with respect to the plate surface direction of the perforated metal plate.

[0077] By forming each corner region 8 of the polygonal ring 5 constituting the flat porous metal plate 1, 30 according to claim 1 alternately in the circumferential direction as a convex top portion 8 and a concave bottom portion 8, a zigzag shape can be constructed in which the sides connecting the corners are alternately inclined in different directions along the circumferential direction. With this configuration, adjacent through holes are in communication with each other through a linear flow path via the spaces formed above and below each side. Since the porous metal plates 20, 30 form multiple regularly shaped flow paths penetrating along the surface direction of the porous metal plate, when used, for example, as a leaf disc filter retainer (donut plate shape), it becomes possible to efficiently flow a stable flow rate in the radial direction (radial direction, other direction toward the radial center) which is the discharge direction of the molten resin filtered by the filter material in the leaf disc filter type filtration device.

[0078] In addition, the molten resin that is filtered by the two filter media of the leaf disc filter and flows into the retainer joins together through the through hole 2 and each flow path, and then mixes and becomes homogenized within each flow path. If the intervals between the corner regions 8 constituting one polygonal ring 5 (the interval G1 between the convex tops 8 adjacent to each other, and the interval G2 between the concave bottoms 8 adjacent to each other) are too large, when pressure is applied from the molten resin passing through the filter medium, the porous support plate (punching plate) located between the filter medium and the retainer will bend and deform, causing the filter medium to be deformed. On the other hand, if the intervals G1 and G2 are too small, the porosity will decrease and the passage resistance will increase. Although it is difficult to achieve this balance, according to the present invention, fine adjustments can be made by adjusting the opening area of ​​the through hole 2 and the width of each side so that the intervals G1 and G2 are optimal values. Depending on how the intervals G1 and G2 are set, it is also possible to make the leaf disc filter thinner by directly supporting the filter medium with the retainer without providing a porous support plate.

[0079] In the porous metal plates 20, 30, 40 according to the third aspect of the present invention, each of the through holes 2 has substantially the same shape and / or similar shapes. The through holes 2 constituting the vertical through hole row may have the same shape and size, or may have similar shapes. In particular, when used as a retainer for a leaf disc filter, since the overall shape of the retainer is a doughnut plate, the opening area of ​​the through holes 2 on the inner diameter side may be made the smallest, and the opening area may be gradually increased toward the outer diameter side.

[0080] The polygonal ring 5 constituting the perforated metal plate 20 according to the fourth aspect of the present invention is a hexagonal ring, and is characterized in that the vertical through hole rows are arranged in parallel in multiple rows in the horizontal direction, with the vertical positions shifted. When the maximum diameter of the through hole 2 is set to about 10 mm, the polygonal ring body 5 is made to be a hexagonal ring body, which makes the processing easier.

[0081] The filter retainer according to the fifth aspect of the present invention is characterized in that the polygonal ring-shaped body is formed in a doughnut plate shape. The perforated metal plates 20, 30, 40 are used as filter retainers, and when used as leaf disc filter retainers, their overall shape is a doughnut plate.

[0082] The filter retainer according to the sixth aspect of the present invention is characterized in that two flat, doughnut-shaped perforated metal plates 1 are stacked together with the positions of the through holes 2 offset from one another. This corresponds to the fourth embodiment, and one retainer can be formed by stacking two flat porous metal plates 1 with a spacer between them. [Explanation of symbols]

[0083] 1...perforated metal plate, 2...through hole, 5...polygonal ring body, 6...periphery frame (frame body), 6a to 6f...sides, 8...corner region, 8 convex...convex top, 8 concave...concave bottom, 8a to 8f...corner region, 20...perforated metal plate, 25...bend line, 30...perforated metal plate, 40...perforated metal plate, 50...perforated metal plate, 52...column member, 55...side member, 100...leaf disc filter, 102...retainer, 104...hub, 106...punched plate, 108...filter material, 110...ring, 112...spacer.

Claims

1. A retainer for a leaf disc filter, comprising a perforated metal plate having a disk-shaped flat metal plate surface on which a plurality of through holes, each of which is polygonal in plan view, are arranged in a vertical direction, and a plurality of rows of vertical through holes arranged in parallel in a horizontal direction, each of which is surrounded by a polygonal ring-shaped body formed of a narrow band-like outer peripheral frame, Each side of the outer periphery of the polygonal ring is shared with a corresponding side of another adjacent polygonal ring, Each corner of each of the polygonal rings has a flat, small-area convex apex protruding toward the front direction perpendicular to the surface direction of the porous metal plate, and a flat, small-area concave bottom receding toward the rear direction of the porous metal plate, the flat, small-area concave bottom being alternately arranged in the circumferential direction, The convex tops and the concave bottoms are on the same plane, Each side of the outer circumferential frame connecting each of the convex apexes and each of the concave bottoms extends at a predetermined angle with respect to a plate surface direction of the perforated metal plate, a flow path formed linearly along each of the sides constituting the plurality of polygonal rings linearly arranged adjacent to each other, The flow path comprises at least a first flow path extending linearly from the outer peripheral edge of the porous metal plate in the radial direction and having its inner diameter side terminal end at the inner peripheral edge of the porous metal plate, and a second flow path extending linearly from the outer peripheral edge of the porous metal plate in an oblique inner diameter direction and intersecting with the first flow path midway to communicate with the first flow path.

2. 2. The leaf disc filter retainer according to claim 1, wherein each of the through holes has substantially the same shape and / or similar shapes.

3. 2. The leaf disc filter retainer according to claim 1, wherein the polygonal ring is a hexagonal ring.

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