A device for extruding fluid materials.

Abstract

The extrusion die 100 has first and second bodies 114 defining an extrusion cavity 118 therebetween. The extrusion cavity 118 has an inlet 120, a primary manifold 128 extending from the inlet in a flow direction, and an outlet 122 with an elongated slot. In some embodiments, the cavity has an intermediate chamber 130 extending from the primary manifold 128 in a flow direction, the intermediate chamber having back lines 122a, 128a, 130a, 132a, 134a and front lines 122b, 128b, 130b, 132b, 134b that taper away from each other as they extend outward toward opposite ends of the die. The primary manifold 128 has a forward end 128D portion defined between opposing inner surfaces 114a, 129a, 131a, at least one of the inner surfaces 114a, 116a tapering toward the other as it extends along the flow direction.

Description

[Technical Field]

[0001] This disclosure (the present invention) generally relates to extrusion apparatus, and more particularly to extrusion dies for extruding fluid materials and methods for using the same.

[0002] [Cross-reference of related applications] This application is a claim application for interest in U.S. Provisional Application No. 63 / 123,591, filed on 10 December 2020, which is referenced by reference and whose entire contents are incorporated herein by reference for all purposes. [Background technology]

[0003] Conventionally, extrusion dies have been used to extrude molten thermoplastic resin into a film or sheet. An extrusion die has first and second die bodies, with an extrusion cavity formed between them, through which the molten thermoplastic resin is extruded. The extrusion cavity has a die inlet, a die outlet, and one or more chambers located between the die inlet and the die outlet that distribute the molten thermoplastic resin from the die inlet to the die outlet. For example, in one example of a conventional extrusion die, the extrusion cavity has a die inlet, a coat hanger-shaped primary manifold located downstream of the die inlet, a triangular preland section located downstream of the primary manifold, a meltwell (also known as a secondary relief or secondary manifold) located downstream of the preland section, and a die outlet located downstream of the meltwell. The preland section introduces resistance to the flow that varies with the width of the die, resulting in the thermoplastic resin flow being spread uniformly in the transverse direction. The die exit may be formed between opposing lips of the extrusion die, and it is preferable that at least one of these lips be adjustable to adjust the lip gap (e.g., lip depth) of the die exit.

[0004] U.S. Patent No. 5,949,429 discloses an extrusion die with a primary manifold having a backline parallel to the die exit, where the distance between the backline and the exit is constant across the entire width of the extrusion die. The linear backline allows the first and second die bodies to be fastened to each other by fasteners spaced apart along lines parallel to both the backline and the die exit. By spacing the fasteners in this manner, the extrusion die's sensitivity to changes in deflection can be reduced, resulting in uniform deflection (if any) across the entire width of the extrusion die. This reduces the need to adjust one or more lips that define the die exit to obtain the desired contour shape of the extruded sheet. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent No. 5,949,429 [Overview of the project]

[0006] In one embodiment, the extrusion die has a first die body and a second die body, with an extrusion cavity formed between these die bodies. The extrusion cavity has an inlet, a primary manifold, an intermediate chamber, and an outlet. The primary manifold extends from the inlet along the flow direction. The primary manifold has a backline and a frontline spaced apart from the backline along the flow direction. The backline is substantially linear along a second direction perpendicular to the flow direction, with the backline extending outward toward the first and second ends of the extrusion die, which are spaced apart from each other along the second direction. The frontline tapers toward the backline, with the frontline extending outward toward the first and second ends. The intermediate chamber extends from the primary manifold along the flow direction. The intermediate chamber has a backline with the same width as the frontline of the primary manifold and a frontline spaced apart from the backline of the intermediate chamber along the flow direction. The front line of the intermediate chamber tapers away from the back line of the intermediate chamber, extending outward toward the first and second ends. The intermediate chamber has a depth less than the depth of the primary manifold along the flow direction and a third direction perpendicular to the second direction. The outlet is in fluid communication with the primary manifold and the intermediate chamber, and the outlet has an elongated slot along the second direction.

[0007] In another embodiment, the extrusion die comprises a first die body and a second die body, and an extrusion cavity is formed between the die bodies. The extrusion cavity has an inlet, a primary manifold, and an outlet. The primary manifold extends along the flow direction from the inlet. The primary manifold has a rear end portion and a front end portion extending along the flow direction from the rear end portion. The front end portion is defined by opposed front inner surfaces of the first and second die bodies, respectively. At least one of the opposed front inner surfaces is tapered toward the other of the front inner surfaces while extending along the flow direction. At least one of the opposed front inner surfaces has a first curved portion extending from the rear end portion of the primary manifold toward a front line, and a second curved portion extending from the front line toward the rear end portion. The outlet is in fluid communication with the primary manifold along the flow direction, and the outlet comprises an elongated slot extending along a second direction.

[0008] The following description of the exemplary embodiments will be better understood when read in conjunction with the accompanying drawings. As will be appreciated, the potentially conceivable embodiments of the disclosed system and method are not limited to the illustrated systems and forms. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] [Figure 1] It is a perspective view of an outlet side of an extrusion die apparatus according to one embodiment. [Figure 2] It is a perspective view of an inlet side of an extrusion die apparatus according to one embodiment. [Figure 3] It is an exploded perspective view of the extrusion die apparatus in Fig. 1. [Figure 4] It is an inner plan view of a first die body of the extrusion die apparatus in Fig. 1. [Figure 5] It is an inner plan view of a first die body of the extrusion die apparatus in Fig. 1. [Figure 6] It is a cross-sectional view of the extrusion die apparatus taken along line 6-6 in Fig. 1. [Figure 7] It is another cross-sectional view of the extrusion die apparatus taken along line 7-7 in Fig. 1. [Figure 8] It is an enlarged cross-sectional view of the primary chamber of the extrusion die apparatus of Figure 1 according to one embodiment. [Figure 9] It is an enlarged cross-sectional view of the primary chamber of the extrusion die apparatus of Figure 1 according to another embodiment. [Figure 10] It is a perspective view of an outlet side of an extrusion die apparatus according to another embodiment, where the first body of the apparatus is shown by imaginary lines, so that the internal cavity of the apparatus can be seen. [Figure 11] It is a cross-sectional view of the extrusion die apparatus taken along line 11-11 of Figure 10. [Figure 12] It is another cross-sectional view of the extrusion die apparatus taken along line 12-12 of Figure 10. [Figure 13] It is a perspective view viewed from above the outlet side of an extrusion die apparatus according to another embodiment, where the first body of the apparatus is shown by imaginary lines, so that the internal cavity of the apparatus can be seen. [Figure 14] It is a perspective view viewed from below the outlet side of the extrusion die apparatus of Figure 13, where the second body of the apparatus is shown by imaginary lines, so that the internal cavity of the apparatus can be seen. [Figure 15] It is a cross-sectional view of the extrusion die apparatus taken along line 15-15 of Figure 13. [Figure 16] It is another cross-sectional view of the extrusion die apparatus taken along line 16-16 of Figure 13. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In conventional extrusion dies, for example, dies in which the primary manifold has a backline parallel to the die exit, the volume of the primary manifold may be too large towards the end of the extrusion die. As a result, the residence time of the fluid extruded through the primary manifold may be long, and residence time is a measure of the time from when the fluid particles enter the extrusion die to when the fluid particles exit the extrusion die. In some embodiments of the present invention, an intermediate chamber is provided that can reduce the volume of the primary manifold from the end of the extrusion die. This can shorten the residence time of the fluid in the extrusion die, and as a result, the extrusion die can produce a uniform distribution of fluid over the entire width of the extrusion die. Additionally or alternatively, in some embodiments, the primary manifold is preferably formed between opposing front inner surfaces. At least one of the opposing front surfaces is preferably tapered toward the other, and such at least one is preferably having at least one radius (r), for example, a pair of radii. As a result of providing one or more radii, the change in shear stress of the fluid flow as the fluid flows through the primary manifold can be reduced. Furthermore, the one or more radii are preferably provided in a primary manifold having an arbitrarily suitable shape, such as a parallel backline, a coat hanger shape, or any other suitable shape. A primary manifold with one or more radii can also be implemented in a die with or without the intermediate chamber described above.

[0011] Referring to Figures 1 and 2, an extrusion die 100 as an embodiment is shown. The extrusion die 100 is configured to extrude a fluid, such as a polymer, such as a monolayer or multilayer molten thermoplastic resin, through the extrusion die to form a film or sheet product. The extrusion die 100 has an inlet side 102 and an outlet side 104 that are spaced apart from each other along a first direction D1. The outlet side 104 is spaced apart from the inlet side 102 along a flow direction parallel to the first direction D1, and the flow direction is the direction of flow from the inlet side 102 to the outlet side 104. The extrusion die 100 has a first end 106 and a second end 108 that are spaced apart from each other along a second direction D2 perpendicular to the first direction D1. The extrusion die 100 has a first side 110 and a second side 112 that are spaced apart from each other along a third direction D3 perpendicular to a first direction D1 and a second direction D2. The extrusion die 100 is preferably elongated from a first end 106 to a second end 108. The extrusion die 100 is preferably having a dimension d1 from the inlet side 102 to the outlet side 104, e.g., length, a dimension d2 from the first end 106 to the second end 108, e.g., width, and a dimension d3 from the first side 110 to the second side 112, e.g., thickness. The width d2 is preferably greater than one or both of the length d1 and the thickness d3. In some embodiments, the length d1 is preferably greater than the thickness d3.

[0012] Referring to Figures 3 to 5, the extrusion die 100 has a joint die body, for example, a first die body 114 and a second die body 116. The first and second bodies are preferably offset from each other along a third direction D3 when the first and second die bodies 114 and 116 are assembled or joined together. The first and second die bodies 114 and 116 are preferably joined to each other using any suitable fasteners. For example, the first and second die bodies 114 and 116 may have a plurality of mounting holes 117, and the extrusion die 100 may have a plurality of bolts (not shown), each bolt configured to fit into a mounting hole 117 of one of the first and second die bodies 114 and 116, and into a mounting hole 117 of the other of the first and second die bodies 114 and 116, thereby fixing the first and second die bodies 114 and 116 to each other. During assembly, an extrusion cavity 118 (labeled in Figures 6 and 7) is formed between the first body 114 and the second body 116. The first body 114 has an inner surface 114a and an outer surface 114b that are opposite to each other along the third direction D3. A first recess 116c is provided in the inner surface 114a, and this first recess defines at least a first portion of the extrusion cavity 118.

[0013] Similarly, the second body 116 has an inner surface 116a and an outer surface 116b that are opposite to each other along the third direction D3. A second recess 116c is formed in the inner surface 116a, and this second recess defines at least a second portion of the extrusion cavity 118. The inner surfaces 114a and 116a face each other when the first and second die bodies 114 and 116 are assembled together. When assembled, the first and second recesses 114c and 116c can come together to form the extrusion cavity 118. In some embodiments, the first and second recesses 114c and 116c are often substantially mirror images of each other, however, not all embodiments of the present invention are limited in this way.

[0014] The extrusion die 100 may be provided with an inlet 120 and an outlet 122. The inlet 120 and the outlet 122 may be offset from each other along a first direction D1. The extrusion cavity 118 may extend from the inlet 120 to the outlet 122. The outlet 122 is configured to extrude a fluid through the outlet to form a film or sheet product. The outlet 122 may extend into the outlet 104 of the extrusion die 100. The outlet 122 may be formed between the first lip 124 of the first die body 114 and the second lip 126 of the second die body 116 with respect to a third direction D3. In other embodiments (not shown), the outlet 122 may be angled with respect to the first direction D1, so that the outlet extends along a direction located between the first direction D1 and the third direction D3. The outlet 122 may have a lip gap having a dimension d4 along the second direction D2, for example, a width, and a dimension d5 along the third direction D3. Dimension d5 may be measured from the first lip 124 to the second lip 126. The width d4 may be greater than dimension d5. Thus, the outlet 122 may have an elongated slot along the second direction D2.

[0015] The inlet 120 may extend into the inlet side 102 of the extrusion die 100. The inlet 120 may have a dimension d6 along the second direction D2, e.g., a width, which is smaller than the width d4 of the outlet 122. For example, the inlet 120 may have a width d6 that is less than half the width d4 of the outlet 122, less than, for example, 3 / 8, less than, for example, 1 / 4, less than, for example, 1 / 8 of the width d4 of the outlet 122. In some embodiments, the inlet 120 may be elongated along the first direction D1. For example, the inlet 120 may have a dimension d7 along the first direction D1, e.g., a length, which is greater than both the width d6 of the inlet 120 along the second direction D2 and the depth of the inlet 120 along the third direction D3. The inlet 120 is preferably located substantially in the center between the first end 106 and the second end 108 of the extrusion die 100, thereby allowing the fluid to be evenly distributed toward the first and second ends 106 and 108. Thus, the extrusion cavity 118 is preferably configured to spread the fluid along the second direction D2 as the fluid moves from the inlet 120 to the outlet 122.

[0016] Referring to Figures 3 to 5, the extrusion cavity 118 may have multiple chambers. These chambers may be offset from one another along a third direction D3. Each of these chambers may be elongated along a second direction D2. For example, each of these chambers may have a dimension along the second direction D2 that is greater than both the dimensions of the chamber along the first direction D1 and the dimensions of the chamber along the third direction D3. In some embodiments, each chamber may have a dimension along the second direction D2 that is substantially equal to the width d4 of the outlet 122.

[0017] The multiple chambers of the extrusion cavity 118 may be configured as a chamber referred to herein as the primary manifold 128. In some embodiments, as shown in Figures 3 to 5, the multiple chambers may be configured as a chamber referred to herein as the intermediate chamber, offset from the primary manifold 128 along the downstream direction. The downstream direction may extend from the inlet side 102 to the outlet side 104, and this downstream direction may be aligned with the first direction D1. The multiple chambers may be configured as a chamber referred to herein as the preland 132, offset from the primary manifold 128 (and the intermediate chamber 130, if configured) along the downstream direction. Thus, the intermediate chamber 130 (if configured) may be located between the primary manifold 128 and the preland 132 along the first direction D1. The multiple chambers may be configured as a chamber referred to herein as the secondary manifold 134, offset from the preland 132 along the downstream direction. Thus, the preland 132 is preferably located between (1) an intermediate chamber 130 (if configured) or a primary manifold 128 (if the intermediate chamber 130 is not configured) and (2) a secondary manifold 134, along the first direction D1. The multiple chambers may constitute an outlet 122, which is offset from the secondary manifold 134 along the downstream direction. Thus, the secondary manifold 134 is preferably located between the preland 132 and the outlet 122, along the first direction D1. As can be understood, in modified embodiments, the extrusion die 100 may not have one or more of the chambers described above, or the extrusion die 100 may have one or more chambers not disclosed above. In one modified embodiment, the extrusion die 100 may not have an intermediate chamber 130.

[0018] The primary manifold 128 is preferably extended along a first direction D1 from the inlet 120 toward the outlet 122. Thus, the inlet 120 is preferably terminated at the primary manifold 128. The primary manifold 128 is in fluid communication with the inlet 120 and is configured to discharge the fluid along a second direction D2 across the entire width of the extrusion die 100. The primary manifold 128 is preferably having a back line 128a and a front line 128b that are offset from each other along the first direction D1. The back line 128a is preferably extended from the inlet 120 along the second direction D2, and the front line 128b is preferably located at a distance from the inlet 120 along the first direction D1. At least a portion of the back line 128a is preferably linear along the second direction D2. In a preferred embodiment, the entire backline 128a is preferably linear along the second direction D2. The backline 128a is preferably substantially parallel to the outlet 122. As a result of forming the backline 128a linearly, the bolts that hold the mounting holes 117, and thus the first and second die bodies 114, 116, can be positioned along the backline 128a at equal intervals from the die outlet 122, without having to position some bolts along the backline 128a further away from the outlet 122 than other bolts. This substantially reduces the risk of the first and second die bodies 114, 116 separating at the manifold backline under pressure, and also prevents leakage between the first die body 114 and the second die body 116 at the manifold backline.

[0019] The front line 128b of the primary manifold 128 is preferably tapered toward the back line 128a as the front line 128b extends outward toward the first and second ends 106,108 of the extrusion die 100. The primary manifold 128 may have a dimension d8, e.g., length, along a first direction D1 from the back line 128a to the front line 128b, where the length d8 decreases as the primary manifold 128 extends toward the first and second ends 106,108. Thus, the length d8 is preferably greater toward the center of the primary manifold 128 than its length toward the first and second ends 106,108. The primary manifold 128 may also have a dimension d9, e.g., height or depth, along a third direction D3. The height or depth d9 is preferably decreased as the primary manifold 128 extends toward the first and second ends 106,108. As can be understood, in the modified embodiment, the primary manifold 128 can have any other suitable shape when viewed in a cross-sectional plane perpendicular to the third direction D3, for example, it can have a coat hanger shape or a T-shape.

[0020] Referring to the cross-sectional views in Figures 6 and 7, the primary manifold 128 preferably has a rear end 128c and a front end 128d. In some embodiments, the height or depth d9 of the primary manifold 128 at the rear end 128c, as viewed in the cross-sectional plane, preferably is substantially uniform or constant as the rear end 128c extends toward the front end 128d. The front end 128d preferably tapers inward as viewed in the cross-sectional plane as it extends from the rear end 128c toward the front line 128b of the primary manifold 128. Thus, the height or depth d9 preferably decreases as the front end 128d extends from the rear end 128c toward the front line 128b.

[0021] Referring particularly to Figure 8, an enlarged view of the primary manifold 128 is shown according to one embodiment. The first die body 114 preferably has a rear inner surface 129a and a front inner surface 129b extending from the rear inner surface 129a toward the front line 128b. The rear inner surface 129a and the front inner surface 129b constitute the first side of the primary manifold 128. Similarly, the second die body 116 preferably has a rear inner surface 131a and a front inner surface 131b extending from the rear inner surface 131a toward the front line 128b. The rear inner surface 131a and the front inner surface 131b constitute the second side of the primary manifold 128. The inner surfaces 129a and 129b preferably face each other so as to form the primary manifold 128 between them. When viewed in cross-sectional plane, the height or depth d9 of the primary manifold 128 from the rear end inner surface 129a to the rear end inner surface 131a is preferably constant along the first direction D1. The front end inner surfaces 129b and 131b are preferably such that they extend from the rear end surfaces 129a and 131a toward the front line 128b and converge toward each other.

[0022] The front inner surface 129b preferably has a first curved portion 129c extending from the rear inner surface 129a toward the front line 128b. The first curved portion 129c preferably curves inward toward the second body 116 (viewed from the inside of the primary manifold 128) in a concave shape as it extends toward the front line 128b. The first curved portion 129c preferably has a radius of curvature that changes as it extends outward toward the first and second ends 106, 108 of the extrusion die 100. For example, the radius of curvature of the first curved portion 129c preferably increases as it extends outward toward the first and second ends 106, 108 of the extrusion die 100. In the modified embodiment, the radius of curvature is preferably constant when the first curved portion 129c extends outward toward the first and second ends 106, 108 of the extrusion die 100. The radius of curvature is preferably in the range of (depth d9÷4) to (depth d9×10).

[0023] The front inner surface 129b preferably has a second curved portion 129d extending from the front line 128b toward the rear inner surface 129a. The second curved portion 129d preferably curves outward (when viewed from the inside of the primary manifold 128) in a convex shape as it extends toward the back line 128a and moves away from the second body 116. The second curved portion 129d preferably has a radius of curvature that changes as it extends outward toward the first and second ends 106, 108 of the extrusion die 100. For example, the radius of curvature of the second curved portion 129d preferably increases as it extends outward toward the first and second ends 106, 108 of the extrusion die 100. In the modified embodiment, the radius of curvature is preferably constant when the second curved portion 129d extends outward toward the first and second ends 106, 108 of the extrusion die 100. The radius of curvature is preferably in the range of (depth d9 ÷ 4) to (depth d9 × 25).

[0024] In some embodiments, the first curved portion 129c and the second curved portion 129d are preferably in contact with each other. In some embodiments, the first curved portion 129c and the second curved portion 129d are adjacent to each other such that the front end surface 129b curves continuously from the rear end surface 129a to the front line 128b, with no straight portion extending from the first curved portion 129c to the second curved portion 129d. In other embodiments, the front end inner surface 129b is preferably having a straight portion 129e extending from the first curved portion 129c to the second curved portion 129d. In some embodiments, only 1 / 3 of the dimension of the front end surface 129b extending from the rear end surface 129a to the front line 128b is straight.

[0025] Similarly, the front inner surface 131b preferably has a first curved portion 131c extending from the rear inner surface 131a toward the front line 128b. The first curved portion 131c preferably curves inward toward the first body 114 (viewed from the inside of the primary manifold 128) in a concave shape as it extends toward the front line 128b. The first curved portion 131c preferably has a radius of curvature that changes as it extends outward toward the first and second ends 106, 108 of the extrusion die 100. For example, the radius of curvature of the first curved portion 131c preferably increases as it extends outward toward the first and second ends 106, 108 of the extrusion die 100. In the modified embodiment, the radius of curvature is preferably constant when the first curved portion 131c extends outward toward the first and second ends 106, 108 of the extrusion die 100. The radius of curvature is preferably in the range of (depth d9 ÷ 4) to (depth d9 × 10).

[0026] The front inner surface 131b preferably has a second curved portion 131d extending from the front line 128b toward the rear inner surface 129a. The second curved portion 131d preferably curves outward (when viewed from the inside of the primary manifold 128) in a convex shape as it extends toward the back line 128a and moves away from the first body 114. The second curved portion 131d preferably has a radius of curvature that changes as it extends outward toward the first and second ends 106, 108 of the extrusion die 100. For example, the radius of curvature of the second curved portion 131d preferably increases as it extends outward toward the first and second ends 106, 108 of the extrusion die 100. In the modified embodiment, the radius of curvature is preferably constant when the second curved portion 131d extends outward toward the first and second ends 106, 108 of the extrusion die 100. The radius of curvature is preferably in the range of (depth d9 ÷ 4) to (depth d9 × 25).

[0027] In some embodiments, the first curved portion 131c and the second curved portion 131d are preferably in contact with each other. In some embodiments, the first curved portion 131c and the second curved portion 131d are adjacent to each other such that the front end surface 131b curves continuously from the rear end surface 129a to the front line 128b, with no straight portion extending from the first curved portion 131c to the second curved portion 131d. In other embodiments, the front end inner surface 131b is preferably having a straight portion 131e extending from the first curved portion 131c to the second curved portion 131d. In some embodiments, only 1 / 3 of the dimension of the front end surface 131b extending from the rear end surface 131a to the front line 128b is straight.

[0028] Although the embodiment shown in Figure 8 has been described as having four curved sections 129c, 129d, 131c, and 131d, embodiments of the present invention are not limited thereto. In modified embodiments, the primary manifold 128 may have as few as one curved section, or up to four curved sections in total.

[0029] Referring briefly to Figure 9, an enlarged view of the primary manifold 128 is shown according to another embodiment. In this embodiment, as with the embodiment in Figure 8, the first die body 114 may have a rear inner surface 129a and a front inner surface 129b, and the second die body 116 may have a rear inner surface 131a and a front inner surface 131b. The rear inner surfaces 129a and 131a may be configured as described above. However, unlike the primary manifold 128 in Figure 8, where the front surfaces 129b and 131b are curved, the primary manifold 128 in Figure 9 has angled front surfaces 129b and 131b. In particular, the front inner surfaces 129b and 131b are straight when these inner surfaces extend from the rear inner surfaces 129a and 131a to the front line 128b of the primary manifold 128, respectively. The front inner surfaces 129b and 131b should extend from the rear inner surfaces 129a and 131a toward the front line 128b, and converge toward each other. The front inner surfaces 129b and 131b should terminate at the rear inner surfaces 129a and 131a at the lines 129f and 131f, respectively. Furthermore, the front inner surfaces 129b and 131b should terminate at the front line 128b at the lines 129g and 131g, respectively.

[0030] The line 129f is preferably defined as having its apex between the rear inner surface 129a and the front inner surface 129b. An angle α1 is preferably defined between the rear inner surface 129a and the front inner surface 129b. α1 is preferably changed as the rear inner surface 129a and the front inner surface 129b extend outward toward the first and second ends 106, 108 of the extrusion die 100. For example, the angle α1 is preferably increased as the rear inner surface 129a and the front inner surface 129b extend outward toward the first and second ends 106, 108 of the extrusion die 100. As a modified example, the angle α1 is preferably constant when the rear inner surface 129a and the front inner surface 129b extend outward toward the first and second ends 106, 108 of the extrusion die 100.

[0031] The line 131f is preferably defined as having its apex between the rear inner surface 131a and the front inner surface 131b. An angle α2 is preferably defined between the rear inner surface 131a and the front inner surface 131b. α2 is preferably changed as the rear inner surface 131a and the front inner surface 131b extend outward toward the first and second ends 106, 108 of the extrusion die 100. For example, the angle α2 is preferably increased as the rear inner surface 131a and the front inner surface 131b extend outward toward the first and second ends 106, 108 of the extrusion die 100. As a modified example, the angle α2 is preferably constant when the rear inner surface 131a and the front inner surface 131b extend outward toward the first and second ends 106, 108 of the extrusion die 100.

[0032] Line 129g is preferably defined at the end of the front inner surface 129b opposite to line 129f, for example, between the front inner surface 129b and the surface defining the next chamber. An angle α3 is preferably defined between the front inner surface 129b and the surface defining the next chamber. α3 is preferably changed as the front inner surface 129b extends outward toward the first and second ends 106,108 of the extrusion die 100. For example, the angle α3 is preferably increased as the front inner surface 129b extends outward toward the first and second ends 106,108 of the extrusion die 100. As a modified example, the angle α3 is preferably constant when the front inner surface 129b extends outward toward the first and second ends 106,108 of the extrusion die 100.

[0033] Line 131g is preferably defined at the end of the front inner surface 131b opposite to line 131f, for example, between the front inner surface 131b and the surface defining the next chamber. An angle α4 is preferably defined between the front inner surface 131b and the surface defining the next chamber. α4 is preferably changed as the front inner surface 131b extends outward toward the first and second ends 106,108 of the extrusion die 100. For example, the angle α4 is preferably increased as the front inner surface 131b extends outward toward the first and second ends 106,108 of the extrusion die 100. As a modified example, the angle α4 is preferably constant when the front inner surface 131b extends outward toward the first and second ends 106,108 of the extrusion die 100.

[0034] Compared to the primary manifold 128 in the embodiment of Figure 9, in which the front end surfaces 129b and 131b are angled, the primary manifold 128 in Figure 8, having curved front end surfaces 129b and 131b, can reduce the change in shear stress of the fluid flow as the fluid flows through the primary manifold 128. As a result, a more uniform flow direction of the fluid is obtained inside the extrusion die 100, and even further out. As a result of providing the curved portions 129c, 129d, 131c, and 131d, greater flexibility is obtained when designing the shape of the manifold, and the fluid can be spread evenly across the entire width of the extrusion die 100 while reducing the shear stress applied to the fluid. As can be seen, virtually any primary manifold design, whether conventionally devised or not, can be equipped with curved front end surfaces in much the same way as in the embodiment of Figure 8. This can be implemented without any restrictions on the shape of the manifold or the shape of the preland (which will be further explained below). Furthermore, the curved front surface can be used for coat hanger-shaped manifolds, T-shaped manifolds, manifolds with a straight backline, manifolds with an inverted preland, or any other suitable manifold shape.

[0035] Referring back to Figures 3 to 5, the multiple chambers of the extrusion cavity 118 of the extrusion die 100 may optionally have an intermediate chamber 130 extending from the primary manifold 128 toward the outlet 122 along a first direction D1. The intermediate chamber 130 is preferably in fluid communication with the primary manifold 128 and the inlet 120. The intermediate chamber 130 is preferably having a back line 130a and a front line 130b that are offset from each other along the first direction D1. The back line 130a is preferably having the same spread as the front line 128b of the primary manifold 128. The back line 130a is preferably tapered away from the front line 130b as the back line 130a extends outward toward the first and second ends 106, 108 of the extrusion die 100. Similarly, the front line 130b is preferably tapered away from the back line 130a as the front line 130b extends outward toward the first and second ends 106, 108 of the extrusion die 100. As a result, the intermediate chamber 130 can have a bow tie cross-sectional shape in a plane perpendicular to the third direction D3. The intermediate chamber 130 has a dimension d along the first direction from the back line 130a to the front line 130b. 10 For example, it can have a length, and length d 10 The intermediate chamber 130 increases in length as it extends toward the first and second ends 106, 108. Thus, the length d 10 It is preferable that its length be greater toward the first and second ends 106,108 than toward the center of the primary manifold 128.

[0036] Referring to the cross-sectional views in Figures 6 and 7, the intermediate chamber 130 also has dimensions d along the third direction D3. 11 It is preferable to have a gap with d. 11 It is preferable that this is constant when the intermediate chamber 130 extends toward the first and second ends 106, 108. Dimension d 11 It is preferable that the height or depth d9 of the primary manifold 128 be smaller than the dimension d 11It is preferable that the dimension d is constant when the intermediate chamber 130 extends along the first direction D1 between the back line 130a and the front line 130b. However, it should be noted that the intermediate chamber 130 preferably has a front end portion that tapers inward when the intermediate chamber 130 extends along the first direction to the front line 130b, and as a result the dimension d 11 It is designed to reduce to the dimensions of Preland 132.

[0037] In conventional extrusion dies with a primary manifold having a linear backline, the volume of the primary manifold channel may become too large towards both ends of the extrusion die. This can result in a longer polymer residence time. In Figures 3 to 5, the intermediate chamber 130 can reduce the volume of the primary manifold 128 toward each end 106, 108 of the extrusion die 100. Since the frontline 128b of the primary manifold 128 tapers upstream toward each end 106, 108 of the extrusion die 100, the length d8 of the primary manifold 128 toward the first and second ends 106, 108 can be smaller than the length of an equivalent conventional extrusion die 100 having a primary manifold with a linear backline. Furthermore, the height or depth d9 of the primary manifold 128 is also preferably tapered as the primary manifold 128 extends toward each end 106, 108. This allows for a further reduction in volume at the first and second ends 106,108 compared to an equivalent conventional extrusion die 100. The intermediate chamber 130 can facilitate a uniform fluid distribution across the entire width of the extrusion die 100 along the second direction D2.

[0038] Referring back to FIGS. 3 to 5, the plurality of chambers of the extrusion cavity 118 of the extrusion die 100 may preferably include a pre-land 132 extending from the intermediate chamber 130 toward the outlet 122 along the first direction D1. The pre-land 132 is in fluid communication with the intermediate chamber 130, and consequently the primary manifold 128 and the inlet 120. Notably, in a modified embodiment not provided with the intermediate chamber 130, the pre-land 132 may preferably extend from the primary manifold 128 toward the outlet 122 along the first direction D1, as shown in FIGS. 10 and 14, and the pre-land 132 may preferably be in fluid communication with the primary manifold 128.

[0039] The pre-land 132 may preferably include a back line 132a and a front line 132b offset from each other along the first direction D1. The back line 132a may preferably be coextensive with the front line 130b of the intermediate chamber 130 or the front line 128b of the primary manifold 128 (in embodiments where the intermediate chamber 130 is not provided). The back line 132a may preferably taper toward the front line 132b while extending outward toward the first and second ends 106, 108 of the extrusion die 100. At least a portion (up to the entire) of the front line 132b may preferably be linear along the second direction D2 when the front line 132b extends outward toward the first and second ends 106, 108 of the extrusion die 100. The front line 132b may preferably be substantially parallel to the outlet 122. Thus, the pre-land 132 may preferably have a substantially triangular cross-sectional shape in a plane perpendicular to the third direction D3. The pre-land 132 has a dimension d along the first direction from the back line 132a to the front line 132b 12 , for example a length, and the length d 12 decreases as the intermediate chamber 130 extends toward the first and second ends 106, 108. Thus, the length d 10 may preferably be smaller toward the first and second ends 106, 108 than toward the center of the pre-land 132.

[0040] Typically, a pressure drop occurs from the center of the primary manifold 128 as the fluid spreads out in a fan shape toward the first and second ends 106,108. The preland 132 is configured to elongate toward the center of the extrusion die 100 so as to reduce the pressure near the center, thereby making the pressure uniform across the entire width of the extrusion die 100. Preferably, the preland 132 should be configured such that the velocity, pressure, and shear stress of the fluid material at the ends of the preland 132 are uniform across the entire width of the extrusion die 100 along the second direction D2.

[0041] Referring to the cross-sectional views in Figures 6 and 7, the preland 132 is dimensioned d along the third direction D3. 13 For example, it is preferable to define a pre-land gap having a height or depth. Height or depth d 13 It is preferable that this is constant when the preland 132 extends toward the first and second ends 106, 108. As a modification, the height or depth d 13 The preland 132 may increase in height or depth d as it extends toward the first and second ends 106, 108. 13 The dimensions d of the intermediate chamber 130 11 And it is preferable that it be smaller than the height or depth d9 of the primary manifold 128. 13 It is preferable that the preland 132 is constant when it extends along the first direction D1 between the backline 132a and the frontline 132b. However, it is noteworthy that the preland 132 is preferable to be tapered outward at its front end to the frontline 132b so that it is positioned adjacent to the secondary manifold 134.

[0042] Referring back to Figures 3 to 5, the multiple chambers of the extrusion cavity 118 of the extrusion die 100 may have a secondary manifold 134, sometimes called a meltwell, extending from the preland 132 toward the outlet 122 along a first direction D1. The secondary manifold 134 may be in fluid communication with the preland 132, and consequently with the intermediate chamber 130, primary manifold 128, and inlet 120. The secondary manifold 134 may have a backline 134a and a frontline 134b offset from each other along the first direction D1. The backline 134a may have the same extent as the frontline 132b of the preland 132.

[0043] At least a portion (up to its entirety) of the back line 134a is preferably linear along the second direction D2 when the back line 134a extends outward toward the first and second ends 106, 108 of the extrusion die 100. The back line 134a is preferably substantially parallel to the exit 122. Similarly, at least a portion (up to its entirety) of the front line 134b is preferably linear along the second direction D2 when the front line 134b extends outward toward the first and second ends 106, 108 of the extrusion die 100. The front line 134b is preferably substantially parallel to the exit 122. Thus, the secondary manifold 134 is preferably rectangular in cross-sectional shape in a plane perpendicular to the third direction D3. The secondary manifold 134 is preferably dimension d along the first direction from the back line 134a to the front line 134b. 14 For example, it is preferable that it has a length, such as length d 14 This is constant when the secondary manifold 134 extends toward the first and second ends 106,108. Thus, length d 14The lines are preferably identical at the center of the secondary manifold 134 and at the first and second ends 106, 108. If an intermediate chamber 130 is provided, the preland 132 is preferably configured as shown in the figure, with its triangular tip facing the inlet, and the front line 132b of the preland 132 is preferably substantially parallel to the outlet 122. This allows the secondary manifold 134 to take a rectangular shape, thereby promoting a more linear fluid flow in the first direction D1 across the entire width of the secondary manifold 134 and toward the outlet 122. This is in contrast to conventional extrusion dies having an inverted preland (i.e., the triangular tip facing toward the outlet). In such conventional dies, as a result of the inverted preland, the dimensions of the secondary manifold change from the center to the end of the die. As a result, lateral fluid flow (i.e., flow along the second direction D2) may occur in the secondary manifold at times when lateral fluid flow is undesirable.

[0044] Referring to the cross-sectional views in Figures 6 and 7, the secondary manifold 134 is oriented along the third direction D3, with dimension d 15 For example, it is preferable that it has a height or depth. Height or depth d 15 It is preferable that the height or depth d is constant when the secondary manifold 134 extends toward the first and second ends 106, 108. 15 The height or depth d of the pre-land 132 is 13 It is better if it is larger than d. In some embodiments, the height or depth d 15 The dimensions d of the intermediate chamber 130 11 Larger than d is better. Height or depth d 15It is preferable that the secondary manifold 134 is constant when it extends from the back line 134a toward the front line 134b along the first direction D1. However, it is noteworthy that the secondary manifold 134 is preferable to be tapered inward at its front end toward the front line 134b so as to be located adjacent to the outlet 122. The secondary manifold 134 is configured to have a height or depth greater than the height or depth of the preland 132, and as a result, the secondary manifold 134 acts to decelerate the fluid velocity. By decelerating the velocity, the fluid pressure on the first lip 124 and the second lip 126 is reduced, and this pressure would, if not configured so, cause the lips 124 and 126 to flex and move away from each other.

[0045] Referring back to Figures 3 to 5, the multiple chambers of the extrusion cavity 118 of the extrusion die 100 preferably have outlets 122 extending away from the inlet 120 along a first direction D1 from the secondary manifold 134. The outlets 122 preferably have fluid communication with the secondary manifold 134, and consequently with the preland 132, intermediate chamber 130, primary manifold 128, and inlet 120. The outlets 122 preferably have back lines 122a and front lines 122b that are offset from each other along the first direction D1. The back line 122a preferably has the same spread as the front line 132b of the secondary manifold 134. At least a portion, and up to its entirety, of the back line 122a is preferably linear along the second direction D2 when the back line 122a extends outward toward the first and second ends 106, 108 of the extrusion die 100. Similarly, at least a portion, and up to its entirety, of the front line 122b is preferably linear along the second direction D2 when the front line 122b extends outward toward the first and second ends 106, 108 of the extrusion die 100. As a result, the exit 122 is preferably rectangular in cross-sectional shape in a plane perpendicular to the third direction D3. The exit 122 is preferably along the first direction from the back line 122a to the front line 122b with respect to dimension d 16For example, it is preferable that it has a length, such as length d 16 This is constant when the outlet 122 extends toward the first and second ends 106,108. Thus, length d 16 It is preferable that this is the same at the center of the exit 122 and at the first and second ends 106, 108.

[0046] Referring to the cross-sectional views in Figures 6 and 7, the outlet 122 is preferably defined as having a gap of dimension d5 along the third direction D3. Dimension d5 is the dimension d of the secondary manifold 134. 15 It is better if it is smaller than d. In some embodiments, dimension d5 is the height or depth d of the preland 132. 13 It is preferable that it be smaller than . The exit 122 is preferably composed of a lip 124 of the first die body 114 and a lip 126 of the second die body 116. In some embodiments, the first die body 114 is preferably having a hinge 125, which is configured to bend to fine-tune dimension d5 by moving at least a portion of lip 124 closer to or further away from lip 126 along a third direction D3. Although not shown, a plurality of adjusters are preferably spaced apart from each other along a second direction D2, each adjuster being configured to engage with lip 124 and move another portion of lip 126 along the third direction D3. Lip 124 is preferably configured to be adjusted by the adjusters so that dimension d5 can be changed along the second direction D2 to obtain a desired contour shape of the extruded sheet. Thus, lip 124 can be considered a flexible lip. On the other hand, it is preferable that the lip 126 is a fixed lip that does not move relative to the rest of the second die body 116.

[0047] Referring to Figures 10 to 12, the extrusion die 100' is illustrated according to another embodiment. The extrusion die 100' has several features similar to those described above with respect to the extrusion die 100 in Figures 1 to 9. Therefore, identical features are indicated by the same reference numerals, and the above description of such features applies equally to the corresponding features in Figures 10 to 12. In this embodiment, the extrusion die 100' comprises an extrusion cavity 118 having an inlet 120, a primary manifold 128', a preland 132, a secondary manifold 134, and an outlet 122. The inlet 120, preland 132, secondary manifold 134, and outlet 122 are preferably configured as described above in relation to the extrusion die 100 in Figures 1 to 9. However, the extrusion die 100' lacks the intermediate chamber 130 shown in Figures 1 to 9, and as a result, the primary manifold 128' shown in Figures 10 to 12 has a front line 128b' which has a slightly different configuration from the primary manifold 128 shown in Figures 1 to 9.

[0048] In particular, the front line 128b' is preferably tapered so as to extend outward toward the first and second ends 106, 108 of the extrusion die 100 while moving away from the back line 128a. In some embodiments, the front line 128b' is preferably linear when it extends toward the first end 106 and also linear when it extends toward the second end 108. In other embodiments (not shown), the front line 128b' is preferably curved toward the back line 128a when it extends toward the first end 106 to form an arc of the first circle and also curved toward the back line 128a when it extends toward the second end 108 to form an arc of the second circle. The primary manifold 128 may have a dimension d8, for example, a length, along a first direction from the back line 128a to the front line 128b', the length d8 increasing as the primary manifold 128' extends toward the first and second ends 106,108. Thus, the length d8 may be greater toward the first and second ends 106,108 than toward the center of the primary manifold 128'. Apart from different forms of the front line 128b', the primary manifold 128' may have a rear end 128c and a front end 128d, which may be configured as described above, and may have a cross-section similar to the cross-section described above in relation to Figure 8 or Figure 9.

[0049] Next, referring to Figures 13 to 16, an extrusion die 100″ is shown according to yet another embodiment. The extrusion die 100″ has several features similar to those described above in relation to the extrusion die 100 in Figures 1 to 9. Therefore, identical features are indicated by the same reference numerals, and the above description of such features applies equally to the corresponding features in Figures 13 to 16. In this embodiment, the extrusion die 100″ comprises an extrusion cavity 118 having an inlet 120, a primary manifold 128″, a preland 132″, a secondary manifold 134″, and an outlet 122. The inlet 120 and outlet 122 are preferably configured as described above with respect to the extrusion die 100 in Figures 1 to 9. However, the extrusion die 100″ lacks the intermediate chamber 130 shown in Figures 1 to 9, and the primary manifold 128″, preland 132″, and secondary manifold 134″ have different configurations from the primary manifold 128, preland 132, and secondary manifold 134 shown in Figures 1 to 9, respectively. Furthermore, the first and second recesses provided in the first die body 114 and the second die body 116 together form the extrusion cavity 118, and the first and second recesses are different from each other and thus do not form a mirror image relationship.

[0050] The primary manifold 128'' may have a linear backline 128a similar to the linear backline described above with reference to Figures 1 to 9. However, the frontline 128b'' of the primary manifold 128'' may also be linear along the second direction D2 when the frontline 128b'' extends outward toward the first and second ends 106, 108 of the extrusion die 100''. Thus, the frontline 128b'' may be substantially parallel to the exit 122. The primary manifold 128'' may have a dimension d8, for example, a length, along the first direction from the backline 128a to the frontline 128b'', the length d8 being constant when the primary manifold 128'' extends toward the first and second ends 106, 108. The primary manifold 128'' may have a cross-section similar to the cross-section described above with reference to Figure 8 or Figure 9.

[0051] The preland 132" is preferably linear along the second direction D2 when the backline 132a" extends outward toward the first and second ends 106,108 of the extrusion die 100". Thus, the backline 132a" is preferably substantially parallel to the exit 122. The frontline 132b" of the preland 132" is preferably tapered toward the backline 132a" as the frontline 132b" extends outward toward the first and second ends 106,108 of the extrusion die 100". The preland 132" is preferably linear along the first direction d from the backline 132a" to the frontline 132b". 12 For example, it is preferable that it has a length, such as length d 12 The preland 132″ decreases as it extends toward the first and second ends 106,108. Thus, the length d 12 It is preferable that its length be greater toward the center of the preland 132″ than toward the first and second ends 106,108.

[0052] The secondary manifold 134″ preferably has a back line 134a″, which tapers away from the front line 134b″ as it extends outward toward the first and second ends 106,108 of the extrusion die 100″. The front line 134b″ preferably is linear along the second direction D2 as it extends outward toward the first and second ends 106,108 of the extrusion die 100″. Thus, the front line 134b″ is preferably substantially parallel to the exit 122. The secondary manifold 134″ has a dimension d along the first direction from the back line 134a″ to the front line 134b″. 14 For example, it is preferable that it has a length, such as length d 14 The secondary manifold 134″ increases while extending toward the first and second ends 106,108. Thus, the length d 14 It is preferable that its length be greater towards the first and second ends 106,108 than at the center of the secondary manifold 134″.

[0053] As shown in Figures 15 and 16, the extrusion cavity 118 may have a first side formed by a first die body 114 and a second side located opposite the first side along the third direction D3 and provided by a second die body 116. The first side may be substantially flat across the preland 132'', the secondary manifold 134'', and the outlet 122, and the depth of the second side of the extrusion cavity may vary across the preland 132'', the secondary manifold 134'', and the outlet 122.

[0054] The following are many non-limiting embodiments of various aspects of the present invention. One embodiment includes the following embodiment claim: namely, [Embodiment Claim 1] an extrusion die having a first die body and a second die body, an extrusion cavity formed between the die bodies, the extrusion cavity having an inlet and a primary manifold extending from the inlet in the flow direction, the primary manifold having a back line and a front line spaced apart from the back line in the flow direction, the back line being substantially linear in a second direction perpendicular to the flow direction while extending outward toward the first and second ends of the extrusion die, the front line tapering toward the back line while extending outward toward the first and second ends, and the extrusion cavity extending from the primary manifold The extrusion cavity further comprises an intermediate chamber extending in the direction of flow, the intermediate chamber having a back line having the same width as the front line of the primary manifold and a front line of the intermediate chamber positioned at a distance from the back line of the intermediate chamber in the direction of flow, the front line of the intermediate chamber tapering away from the back line of the intermediate chamber as it extends outward toward the first and second ends, the intermediate chamber having a depth less than the depth of the primary manifold in a third direction perpendicular to the direction of flow and the second direction, and the extrusion cavity further comprises an outlet in fluid communication with the primary manifold and the intermediate chamber, the outlet comprising an elongated slot in the second direction.

[0055] The above embodiments may further include any one or more combinations of the following embodiments: Namely, [Embodiment 2] An extrusion die according to any of the above embodiments, characterized in that the intermediate chamber has a bow tie cross-sectional shape in a plane perpendicular to the third direction. [Embodiment 3] An extrusion die according to any of the above embodiments, characterized in that the extrusion cavity has a preland, the preland having a preland backline and a preland frontline offset from the preland backline along the flow direction, the preland backline having the same spread as the frontline of the intermediate chamber, the preland backline tapering toward the preland frontline while extending outward toward the first and second ends of the extrusion die, and the preland having a depth less than the depth of the intermediate chamber along the third direction. [Embodiment 4] An extrusion die according to any of the above embodiments, characterized in that the preland front line is linear along the second direction while extending outward toward the first and second ends of the extrusion die. [Embodiment 5] An extrusion die according to any of the above embodiments, characterized in that the extrusion cavity has a secondary manifold, the secondary manifold has a back line and a front line offset from the back line of the secondary manifold along the flow direction, the back line of the secondary manifold has the same width as the front line of the preland, the front and back lines of the secondary manifold are linear along the second direction while extending outward toward the first and second ends of the extrusion die, and the secondary manifold has a depth greater than the depth of the preland along the third direction.[Embodiment 6] The primary manifold has a rear end portion and a front end portion extending from the rear end portion along the flow direction, the front end portion is composed of opposing front inner surfaces of the first and second die bodies, at least one of the opposing front inner surfaces tapers toward the other front inner surface while extending along the flow direction, and at least one of the opposing front inner surfaces has a first curved portion extending from the rear end portion toward the front line of the primary manifold and a second curved portion extending from the front line of the primary manifold toward the rear end portion, characterized in that the extrusion die is described in any of the above embodiments. [Embodiment 7] The first curved portion is curved inward in a concave shape toward the extrusion cavity while extending toward the front line, characterized in that the first curved portion curves inward in a concave shape toward the extrusion cavity. [Embodiment Clause 8] An extrusion die according to any of the above embodiments, characterized in that the first curved portion has a radius of curvature that changes as the first curved portion extends outward toward the first and second ends of the extrusion die. [Embodiment Clause 9] An extrusion die according to any of the above embodiments, characterized in that the radius of curvature of the first curved portion increases as the first curved portion extends outward toward the first and second ends of the extrusion die. [Embodiment Clause 10] An extrusion die according to any of the above embodiments, characterized in that the second curved portion curves outward in a convex shape, moving away from the extrusion cavity while extending toward the rear end portion of the primary manifold. [Embodiment Clause 11] An extrusion die according to any of the above embodiments, characterized in that the second curved portion may have a radius of curvature that changes as the second curved portion extends outward toward the first and second ends of the extrusion die. [Embodiment Clause 12] An extrusion die according to any one of the above embodiments, characterized in that the radius of curvature of the second curved portion increases as the second curved portion extends outward toward the first and second ends of the extrusion die.[Embodiment Clause 13] An extrusion die according to any of the above embodiments, characterized in that the first curved portion and the second curved portion are in contact with each other. [Embodiment Clause 14] An extrusion die according to any of the above embodiments, characterized in that the first curved portion and the second curved portion are adjacent to each other such that the front inner surface is continuously curved from the rear end portion of the primary manifold to the front line, with no straight portion extending from the first curved portion to the second curved portion. [Embodiment Clause 15] An extrusion die according to any of the above embodiments, characterized in that the front inner surface has a straight portion extending from the first curved portion to the second curved portion. [Embodiment Clause 16] An extrusion die according to any of the above embodiments, characterized in that only 1 / 3 of the dimension of the front surface extending from the rear end surface of the primary manifold to the front line is straight.

[0056] One embodiment includes the following embodiment clause: namely, [Embodiment Clause 17] an extrusion die having a first die body and a second die body, an extrusion cavity formed between the die bodies, the extrusion cavity having an inlet and a primary manifold extending from the inlet in the direction of flow, the primary manifold having a rear end portion and a front end portion extending from the rear end portion in the direction of flow, the front end portion being composed of opposing front end inner surfaces of the first and second die bodies, at least one of the opposing front end inner surfaces is At least one of the front end surfaces extends along the flow direction and tapers toward the other of the front end surfaces, and at least one of the opposing front end surfaces has a first curved portion extending from the rear end portion of the primary manifold toward the front line and a second curved portion extending from the front line toward the rear end portion, and the extrusion cavity further has an outlet that is in fluid communication with the primary manifold along the flow direction, and the outlet has an elongated slot along the second direction.

[0057] The above embodiments may further include any one or more combinations of the following embodiment claims: namely, [Embodiment Claim 18] an extrusion die according to any of the above embodiment claims, characterized in that the first curved portion is concavely curved inward toward the extrusion cavity while extending toward the front line. [Embodiment Claim 19] an extrusion die according to any of the above embodiment claims, characterized in that the first curved portion has a radius of curvature that changes while extending outward toward the first and second ends of the extrusion die. [Embodiment Claim 20] an extrusion die according to any of the above embodiment claims, characterized in that the radius of curvature of the first curved portion increases while extending outward toward the first and second ends of the extrusion die. [Embodiment Clause 21] An extrusion die according to any of the above embodiments, characterized in that the second curved portion extends toward the rear end portion of the primary manifold and curves outward in a convex shape away from the extrusion cavity. [Embodiment Clause 22] An extrusion die according to any of the above embodiments, characterized in that the second curved portion may have a radius of curvature that changes as the second curved portion extends outward toward the first and second ends of the extrusion die. [Embodiment Clause 23] An extrusion die according to any of the above embodiments, characterized in that the radius of curvature of the second curved portion increases as the second curved portion extends outward toward the first and second ends of the extrusion die. [Embodiment Clause 24] An extrusion die according to any of the above embodiments, characterized in that the first curved portion and the second curved portion are in contact with each other. [Embodiment Clause 25] An extrusion die according to any one of the above embodiments, characterized in that the first curved portion and the second curved portion are adjacent to each other such that the front inner surface is continuously curved from the rear end portion of the primary manifold to the front line, with no straight portion extending from the first curved portion to the second curved portion.[Embodiment Clause 26] An extrusion die according to any of the above embodiments, characterized in that the inner surface of the front end has a straight portion extending from the first curved portion to the second curved portion. [Embodiment Clause 27] An extrusion die according to any of the above embodiments, characterized in that only 1 / 3 of the dimension of the front end surface extending from the rear end surface of the primary manifold to the front line is straight.

[0058] It should be noted that the descriptions and explanations of the illustrated embodiments are for illustrative purposes only and should not be construed as limiting the invention. As will be understood by those skilled in the art, this disclosure envisions a variety of embodiments. Furthermore, it should be understood that the technical ideas described above can be adopted alone or in combination with any of the other embodiments described above in relation to the embodiments described above. Moreover, it should be understood that the various modifications described above in relation to one illustrated embodiment apply to all embodiments described herein unless otherwise specified.

[0059] Conditional words used in the original specification, such as in particular "can" (sometimes translated as "can" or "should"), "could," "might" ("possibly"), or "may," or "eg" ("etc."), generally mean, unless otherwise specified or understood differently within the context in which they are used, that a particular embodiment includes certain features, certain elements, and / or certain steps, while other embodiments do not include them. Thus, such conditional words generally do not suggest that the features, elements, and / or steps are required in any way for one or more embodiments, or that one or more embodiments necessarily include these features, elements, and / or steps. In the original specification, terms such as "comprising" (often translated as "possessing"), "including" (often translated as "containing"), and "having" (often translated as "equipped with") are synonyms and are used comprehensively and non-restrictively, without excluding additional elements, additional features, additional actions, or additional functions.

[0060] While certain embodiments have been described, these embodiments are provided for illustrative purposes only and do not limit the scope of the invention disclosed herein. Thus, nothing in the above description suggests that any particular feature, characteristic, step, module, or block is necessary or essential. Indeed, the novel methods and systems described herein can be embodied in various other forms, and furthermore, various omissions, substitutions, and modifications in the forms of methods and systems described herein can be implemented without departing from the spirit of the invention disclosed herein. The scope of the invention as described in the appended claims and their equivalents are intended to extend to such forms or modifications that fall within the scope and spirit of certain particular aspects of the invention disclosed herein.

[0061] It should be understood that the steps of the exemplary methods described herein do not necessarily have to be performed in the order described, and the order of the steps of such methods should be understood to be merely illustrative. Similarly, additional steps may be included in such methods, and certain steps may be omitted or combined in a manner consistent with various embodiments of the present invention.

[0062] The components of the following method claims (if any) are described in a specific order by corresponding labeling, but unless the claim description otherwise suggests a specific order for carrying out some or all of these components, these components are not necessarily limited to being carried out in that specific order.

[0063] To be understood, when “a” or “one” is used in the original specification to describe a feature such as a component or step, these do not preclude the presence of additional features or a number of features. For example, when referring to an apparatus having or defining “one” of a feature, this does not preclude the apparatus having or defining two or more of the same feature, provided that the apparatus has or defines at least one of the features. Similarly, when referring to “one” of several features in this specification, this does not preclude the invention from including two or more, or at most all, of the features. For example, when referring to an apparatus having or defining “one of X and Y,” this does not preclude the apparatus having both X and Y.

Claims

1. It is an extrusion die. It has a first die body and a second die body, and an extrusion cavity is formed between the die bodies, and the extrusion cavity is It has an entrance, The apparatus has a primary manifold extending from the inlet along the flow direction, the primary manifold having a back line and a front line spaced apart from the back line along the flow direction, the back line being substantially linear along a second direction perpendicular to the flow direction while extending outward toward the first and second ends of the extrusion die which are spaced apart from each other along the second direction, and the front line being tapered toward the back line while extending outward toward the first and second ends. The intermediate chamber extends from the primary manifold along the flow direction, the intermediate chamber having a back line having the same width as the front line of the primary manifold and a front line of the intermediate chamber spaced apart from the back line of the intermediate chamber along the flow direction, the front line of the intermediate chamber tapering away from the back line of the intermediate chamber as it extends outward toward the first and second ends, and the intermediate chamber having a depth less than the depth of the primary manifold along a third direction perpendicular to the flow direction and the second direction. An extrusion die having an outlet in fluid communication with the primary manifold and the intermediate chamber, the outlet having an elongated slot along the second direction.

2. The extrusion die according to claim 1, wherein the intermediate chamber has a bow tie cross-sectional shape in a plane perpendicular to the third direction.

3. The extrusion die according to claim 1 or 2, wherein the extrusion cavity has a preland, the preland has a preland backline and a preland frontline offset from the preland backline along the flow direction, the preland backline has the same spread as the frontline of the intermediate chamber, the preland backline tapers toward the preland frontline while the preland backline extends outward toward the first and second ends of the extrusion die, and the preland has a depth less than the depth of the intermediate chamber along the third direction.

4. The extrusion die according to claim 3, wherein the preland front line is linear along the second direction, extending outward toward the first and second ends of the extrusion die.

5. The extrusion die according to claim 4, wherein the extrusion cavity has a secondary manifold, the secondary manifold has a back line and a front line offset from the back line of the secondary manifold along the flow direction, the back line of the secondary manifold has the same extent as the front line of the preland, the front line and the back line of the secondary manifold are linear along the second direction with the front line and the back line extending outward toward the first and second ends of the extrusion die, and the secondary manifold has a depth greater than the depth of the preland along the third direction.

6. The extrusion die according to claim 1 or 2, wherein the primary manifold has a rear end portion and a front end portion extending from the rear end portion along the flow direction, the front end portion is composed of opposing front inner surfaces of the first and second die bodies, at least one of the opposing front inner surfaces tapers toward the other front inner surface while extending toward the flow direction, and at least one of the opposing front inner surfaces has a first curved portion extending from the rear end portion toward the front line of the primary manifold and a second curved portion extending from the front line of the primary manifold toward the rear end portion.

7. The extrusion die according to claim 6, wherein the first curved portion extends toward the front line and curves concavely inward toward the extrusion cavity.

8. The extrusion die according to claim 6, wherein the first curved portion has a radius of curvature that changes as the first curved portion extends outward toward the first and second ends of the extrusion die.

9. The extrusion die according to claim 8, wherein the radius of curvature of the first curved portion increases as the first curved portion extends outward toward the first and second ends of the extrusion die.

10. The extrusion die according to claim 6, wherein the second curved portion extends toward the rear end portion of the primary manifold and curves outward in a convex shape away from the extrusion cavity.

11. The extrusion die according to claim 10, wherein the second curved portion may have a radius of curvature that changes as the second curved portion extends outward toward the first and second ends of the extrusion die.

12. The extrusion die according to claim 11, wherein the radius of curvature of the second curved portion increases as the second curved portion extends outward toward the first and second ends of the extrusion die.

13. The extrusion die according to claim 6, wherein the first curved portion and the second curved portion are in contact with each other.

14. The extrusion die according to claim 6, wherein the first curved portion and the second curved portion are adjacent to each other such that the front inner surface is continuously curved from the rear end portion of the primary manifold to the front line, with no straight portion extending from the first curved portion to the second curved portion.

15. The extrusion die according to claim 6, wherein the inner surface of the front end has a straight portion extending from the first curved portion to the second curved portion.

16. The extrusion die according to claim 6, wherein only one-third of the dimension of the front inner surface extending from the rear end surface of the primary manifold to the front line is linear.

17. It is an extrusion die, It has a first die body and a second die body, and an extrusion cavity is formed between the die bodies, and the extrusion cavity is It has an entrance, The device has a primary manifold extending from the inlet in the direction of flow, the primary manifold having a rear end portion and a front end portion extending from the rear end portion in the direction of flow, the front end portion being composed of opposing front inner surfaces of the first and second die bodies, at least one of the opposing front inner surfaces tapering toward the other front inner surface while extending in the direction of flow, and at least one of the opposing front inner surfaces having a first curved portion extending from the rear end portion of the primary manifold toward the front line and a second curved portion extending from the front line toward the rear end portion. The primary manifold has an outlet that is in fluid communication with the flow direction, and the outlet has an elongated slot along a second direction. The first curved portion has a radius of curvature that changes as the first curved portion extends outward toward the first and second ends of the extrusion die.

18. The extrusion die according to claim 17, wherein the first curved portion extends toward the front line and curves concavely inward toward the extrusion cavity.

19. The extrusion die according to claim 17, wherein the radius of curvature of the first curved portion increases as the first curved portion extends outward toward the first and second ends of the extrusion die.

20. The extrusion die according to claim 17, wherein the second curved portion extends toward the rear end portion of the primary manifold and curves outward in a convex shape away from the extrusion cavity.

21. The extrusion die according to claim 20, wherein the second curved portion may have a radius of curvature that changes as the second curved portion extends outward toward the first and second ends of the extrusion die.

22. The extrusion die according to claim 21, wherein the radius of curvature of the second curved portion increases as the second curved portion extends outward toward the first and second ends of the extrusion die.

23. The extrusion die according to claim 17 or 18, wherein the first curved portion and the second curved portion are in contact with each other.

24. The extrusion die according to claim 17 or 18, wherein the first curved portion and the second curved portion are adjacent to each other such that there is no straight portion extending from the first curved portion to the second curved portion, and the inner surface of the front end curves continuously from the rear end portion of the primary manifold to the front line.

25. The extrusion die according to claim 17 or 18, wherein the inner surface of the front end has a straight portion extending from the first curved portion to the second curved portion.

26. An extrusion die, It has a first die body and a second die body, and an extrusion cavity is formed between the die bodies, and the extrusion cavity is It has an entrance, The device has a primary manifold extending from the inlet in the direction of flow, the primary manifold having a rear end portion and a front end portion extending from the rear end portion in the direction of flow, the front end portion being composed of opposing front inner surfaces of the first and second die bodies, at least one of the opposing front inner surfaces tapering toward the other front inner surface while extending in the direction of flow, and at least one of the opposing front inner surfaces having a first curved portion extending from the rear end portion of the primary manifold toward the front line and a second curved portion extending from the front line toward the rear end portion. The primary manifold has an outlet that is in fluid communication with the flow direction, and the outlet has an elongated slot along a second direction. An extrusion die in which only one-third of the dimension of the front inner surface extending from the rear end surface of the primary manifold to the front line is straight.

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