Apparatus for extruding a fluid material

Abstract

An extrusion die (100) has first and second die bodies (114) that define an extrusion cavity (118) therebetween. The extrusion cavity (118) has an inlet (120), a primary manifold (128) extending from the inlet (120) in a flow direction, and an outlet (122) defining an elongated slot. In some examples, the cavity has an intermediate chamber (130) extending from the primary manifold (128) in the flow direction, the intermediate chamber (130) having a back line (122A, 128A, 130A, 132A, 134A) and a front line (122B, 128B, 130B, 132B, 134B) that taper away from each other as they extend outwardly toward opposite ends of the die. The primary manifold (128) has a front end (128D) portion defined between opposing interior surfaces (114A, 129A, 131A), at least one interior surface (114A, 116A) tapering toward the other as it extends along the flow direction. In some examples, the interior surfaces (114A, 116A) have first and second curved portions (129C, 131C) that curve to provide a smoother transition from the primary manifold (128) to a downstream chamber (130) of the extrusion cavity (118).

Description

[0001] Cross-reference to related applications

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 123,591, filed on December 10, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates primarily to an extrusion apparatus, and more specifically to an extrusion die for extruding fluid materials and a method of using the same. Background Technology

[0004] Traditionally, extrusion dies have been used to extrude molten thermoplastics into films or sheets. An extrusion die has a first die body and a second die body defining an extrusion cavity therebetween through which molten thermoplastics are extruded. The extrusion cavity has: a die inlet; a die outlet; and one or more chambers between the die inlet and the die outlet that dispense the molten thermoplastics from the die inlet to the die outlet. For example, in a conventional type of extrusion die, the extrusion cavity has: a die inlet; a coat hanger-shaped primary manifold downstream of the die inlet; a triangular preform downstream of the primary manifold; a melt well (otherwise referred to as a secondary discharge or secondary manifold) downstream of the preform; and a die outlet downstream of the melt well. The preform provides resistance to flow that varies across the width of the die, allowing the flow of the thermoplastics to spread laterally uniformly. The die exit can be defined between opposing lips of the extrusion die, at least one lip being adjustable to adjust the lip gap (e.g., its depth) of the die exit.

[0005] U.S. Patent No. 5,949,429 (the teachings of which are incorporated herein by reference in their entirety) discloses an extrusion die having a primary manifold with a back line parallel to the die exit, such that the distance between the back line and the die exit across the width of the extrusion die is constant. The linear back line allows a first die body and a second die body to be fastened together by fasteners spaced apart from each other along a line parallel to both the back line and the die exit. This spacing of the fasteners makes the extrusion die less susceptible to flexural variations, resulting in a more uniform flexural (if any) width across the extrusion die. This, in turn, reduces the need to adjust the lip or multiple lips defining the die exit to obtain the desired profile of the extruded sheet. Summary of the Invention

[0006] In an example, an extrusion die includes a first die body and a second die body defining an extrusion cavity therebetween. The extrusion cavity has an inlet, a primary manifold, an intermediate chamber, and an outlet. The primary manifold extends from the inlet along a flow direction. The primary manifold has a back line and a front line, the front line being spaced apart from the back line along the flow direction. The back line is substantially linear along a second direction as it extends outward toward a first end and a second end of the extrusion die, spaced apart from each other along a second direction perpendicular to the flow direction. The front line tapers toward the back line as it extends outward toward the first and second ends. The intermediate chamber extends from the primary manifold along the flow direction. The intermediate chamber has: a back line, which extends concurrently with the front line of the primary manifold; and a front line, which is spaced apart from the back line 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 as it extends outward toward the first and second ends. The intermediate chamber has a depth in a third direction perpendicular to the flow direction and the second direction, the depth of the intermediate chamber being less than the depth of the primary manifold. The outlet is in fluid communication with the primary manifold and the intermediate chamber, and the outlet defines an elongated slot along the second direction.

[0007] In another example, an extrusion die includes a first die body and a second die body defining an extrusion cavity therebetween. The extrusion cavity has an inlet, a primary manifold, and an outlet. The primary manifold extends from the inlet in a flow direction. The primary manifold has a back end and a front end, the front end extending from the back end in the flow direction. The front end is defined by opposing front end inner surfaces of the first and second die bodies, respectively. At least one of the opposing front end inner surfaces tapers toward the other as it extends in the flow direction. The at least one of the opposing front end inner surfaces has: a first bend extending from the back end toward the front line of the primary manifold; and a second bend extending from the front line toward the back end. The outlet is in fluid communication with the primary manifold in the flow direction and defines a slot elongated in the second direction. Attached Figure Description

[0008] The following description of illustrative embodiments will be better understood when read in conjunction with the accompanying drawings. It should be understood that potential examples of the disclosed systems and methods are not limited to those depicted.

[0009] Figure 1 A perspective view of the outlet side of an extrusion die device according to an example is shown;

[0010] Figure 2 A perspective view of the inlet side of an extrusion die device according to an example is shown;

[0011] Figure 3 It shows Figure 1 Exploded perspective view of the extrusion die equipment;

[0012] Figure 4 It shows Figure 1 A plan view of the inner side of the first die body of the extrusion die device;

[0013] Figure 5 It shows Figure 1 A plan view of the inner side of the first die body of the extrusion die device;

[0014] Figure 6 The image shown is taken at point 6-6 online. Figure 1 A cross-sectional view of the extrusion die head equipment;

[0015] Figure 7 The image shown is taken at point 7-7 online. Figure 1 Another cross-sectional view of the extrusion die device;

[0016] Figure 8 An example is shown. Figure 1 An enlarged cross-sectional view of the primary chamber of the extrusion die device;

[0017] Figure 9 An example based on another example is shown. Figure 1 An enlarged cross-sectional view of the primary chamber of the extrusion die device;

[0018] Figure 10 A perspective view of the outlet side of an extrusion die device according to another example is shown, in which the first die body of the device is shown in dashed lines so that the internal cavity of the device is visible;

[0019] Figure 11 The image shown is taken at position 11-11 online. Figure 10 A cross-sectional view of the extrusion die head equipment;

[0020] Figure 12 The image shown is taken at position 12-12 online. Figure 10 Another cross-sectional view of the extrusion die device;

[0021] Figure 13 A perspective top view of the outlet side of an extrusion die device according to another example is shown, in which the first die body of the device is shown in dashed lines so that the internal cavity of the device is visible;

[0022] Figure 14 It shows Figure 13A perspective bottom view of the outlet side of the extrusion die device, in which the second die body of the device is shown in dashed lines so that the internal cavity of the device is visible;

[0023] Figure 15 The image shown is taken at position 15-15 online. Figure 13 Cross-sectional view of the extrusion die head equipment; and

[0024] Figure 16 The image shown is a screenshot taken at position 16-16 online. Figure 13 Another cross-sectional view of the extrusion die device. Detailed Implementation

[0025] In conventional extrusion dies, such as those in which the primary manifold has a backline parallel to the die outlet, the primary manifold may be too large in volume toward the end of the extrusion die. This can result in a longer residence time for the fluid being extruded, a measure of the time from when fluid particles enter the extrusion die to when they exit. In some examples of this disclosure, an intermediate chamber is included that can reduce the volume of the primary manifold toward the end of the extrusion die. This, in turn, can reduce the residence time of the fluid in the extrusion die and can result in an extrusion die that produces a more uniform distribution of fluid across the width of the extrusion die. Alternatively or additionally, in some examples, the primary manifold may be defined between opposing front inner surfaces. At least one of the opposing front surfaces may taper toward the other and may be implemented with at least one radius, such as a pair of radii. Such radii can cause smaller shear variations in the fluid flow as the fluid flows through the primary manifold. Furthermore, such radii can be implemented on a primary manifold of any suitable shape, including those with parallel backlines, coat hanger shapes, or any other suitable shape. Primary manifolds with radii can also be implemented in molds with or without the intermediate chambers discussed above.

[0026] refer to Figure 1 and Figure 2The image shows an extrusion die 100 according to an example. The extrusion die 100 is configured to extrude a fluid, such as a polymer, such as a single-layer or multi-layer molten thermoplastic, to form a film or sheet product. The extrusion die 100 has an inlet side 102 and an outlet side 104 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, wherein the flow direction is from the inlet side 102 to the outlet side 104. The extrusion die 100 has a first end 106 and a second end 108 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 spaced apart from each other along a third direction D3 perpendicular to the first direction D1 and the second direction D2. The extrusion die 100 may be elongated from the first end 106 to the second end 108. The extrusion die 100 may have: a dimension d1, such as length, from the inlet side 102 to the outlet side 104; a dimension d2, such as width, from the first end 106 to the second end 108; and a dimension d3, such as thickness, from the first side 110 to the second side 112. The width d2 may be greater than one or both of the length d1 and the thickness d3. In some examples, the length d1 may be greater than the thickness d3.

[0027] refer to Figures 3 to 5 The extrusion die 100 includes mating die bodies, such as a first die body 114 and a second die body 116. The first and second die bodies can be offset from each other along a third direction D3 when the first die body 114 and the second die body 116 are assembled together. The first die body 114 and the second die body 116 can be connected to each other using any suitable fastener. For example, the first die body 114 and the second die body 116 may include a plurality of attachment holes 117, and the extrusion die 100 may include a plurality of bolts (not shown), wherein each bolt is configured to extend into the attachment hole 117 of one of the first die body 114 and the second die body 116 and the attachment hole 117 of the other of the first die body 114 and the second die body 116, thereby securing the first die body 114 and the second die body 116 to each other. During assembly, the first die body 114 and the second die body 116 define an extrusion cavity 118 therebetween. Figure 6 and Figure 7 (Selected by the bidder). The first die body 114 has an inner surface 114a and an outer surface 114b that are opposite to each other along a third direction D3. The inner surface 114a defines a first recess 116c therein, which defines at least a first portion of the extrusion cavity 118.

[0028] Similarly, the second die body 116 has an inner surface 116a and an outer surface 116b that are opposite to each other along a third direction D3. The inner surface 116a may define a second recess 116c therein, which defines at least a second portion of the extrusion cavity 118. The inner surfaces 114a and 116a face each other when the first die body 114 and the second die body 116 are assembled together. During assembly, the first recess 114c and the second recess 116c may together define the extrusion cavity 118. In some examples, the first recess 114c and the second recess 116c may be substantially mirror images of each other, but not all examples of this disclosure are subject to this limitation.

[0029] An extrusion die 100 may define an inlet 120 and an outlet 122. The inlet 120 and outlet 122 may be offset from each other along a first direction D1. An extrusion cavity 118 may extend from the inlet 120 to the outlet 122. The outlet 122 is configured to extrude fluid through it to form a film or sheet product. The outlet 122 may extend into an outlet side 104 of the extrusion die 100. The outlet 122 may be defined with respect to a third direction D3 between a first lip 124 of a first die body 114 and a second lip 126 of a second die body 116. In other examples (not shown), the outlet 122 may be angled relative to the first direction D1, such that the outlet extends in a direction between the first direction D1 and the third direction D3. The outlet 122 may define a lip gap having a dimension d4, such as width, along a second direction D2, and a dimension d5 along the third direction D3. The dimension d5 may be measured from the first lip 124 to the second lip 126. The width d4 may be greater than the dimension d5. Therefore, outlet 122 can define a narrow slot that is elongated along the second direction D2.

[0030] Inlet 120 may extend into the inlet side 102 of extrusion die 100. Inlet 120 may have a dimension d6, such as width, along the second direction D2 that is smaller than the width d4 of outlet 122. For example, inlet 120 may have a width d6 that is less than half the width d4 of outlet 122, such as less than three-eighths, such as less than a quarter, such as less than one-eighth. In some examples, inlet 120 may be elongated along the first direction D1. For example, inlet 120 may have a dimension d7, such as length, along the first direction D1 that is greater than both the width d6 of inlet 120 along the second direction D2 and the depth of inlet 120 along the third direction D3. Inlet 120 is preferably substantially centered between the first end 106 and the second end 108 of extrusion die 100 to allow fluid to be evenly distributed toward the first end 106 and the second end 108. Therefore, the extrusion cavity 118 can be configured to spread the fluid along the second direction D2 as the fluid travels from the inlet 120 to the outlet 122.

[0031] refer to Figures 3 to 5 The extrusion cavity 118 may include multiple chambers. The chambers may be offset from each other along a third direction D3. Each chamber may be elongated along a second direction D2. For example, each of the chambers may have a dimension along the second direction D2 that is larger than both the chamber's dimension along the first direction D1 and the chamber's dimension along the third direction D3. In some examples, each chamber may have a dimension along the second direction D2 that is substantially equal to the width d4 of the outlet 122.

[0032] The multiple chambers of the extrusion cavity 118 may include chambers referred to herein as primary manifold 128. In some examples, such as Figures 3 to 5 As shown, the plurality of chambers may include a chamber referred to herein as intermediate chamber 130, which is offset downstream from the primary manifold 128. The downstream direction may extend from the inlet side 102 to the outlet side 104 and may be aligned with the first direction D1. The plurality of chambers may include a chamber referred to herein as preform 132, which is offset downstream from the primary manifold 128 (and intermediate chamber 130 in practice). Thus, intermediate chamber 130 (in practice) may be located between the primary manifold 128 and preform 132 along the first direction D1. The plurality of chambers may include a chamber referred to herein as secondary manifold 134, which is offset downstream from the preform 132. Thus, preform 132 may be located between (1) intermediate chamber 130 (in practice) or primary manifold 128 (when intermediate chamber 130 is not implemented) and (2) secondary manifold 134 along the first direction D1. The plurality of chambers may include an outlet 122, wherein the outlet 122 is offset downstream from the secondary manifold 134. Thus, the secondary manifold 134 may be located between the preform 132 and the outlet 122 along a first direction D1. It should be understood that, in alternative embodiments, the extrusion die 100 may not have one or more of the aforementioned chambers or may include one or more chambers not disclosed above. In an alternative example, the extrusion die 100 may not have the intermediate chamber 130.

[0033] A primary manifold 128 may extend from an inlet 120 toward an outlet 122 along a first direction D1. Thus, the inlet 120 may terminate at the primary manifold 128. The primary manifold 128 is in fluid communication with the inlet 120 and is configured to distribute fluid across the width of the extrusion die 100 along a second direction D2. The primary manifold 128 may have a back line 128a and a front line 128b offset from each other along the first direction D1. The back line 128a may extend from the inlet 120 along the second direction D2, while the front line 128b may be spaced apart from the inlet 120 along the first direction D1. At least a portion of the back line 128a may be linear along the second direction D2. In a preferred embodiment, the entire back line 128a may be linear along the second direction D2. The back line 128a may be substantially parallel to the outlet 122. Forming the back line 128a linearly enables the positioning of attachment holes 117 at points equidistant from the die outlet 122 along the back line 128a, thereby positioning and retaining the bolts holding the first die body 114 and the second die body 116, without causing some bolts along the back line 128a to be spaced further from the outlet 122 than others. This also significantly reduces the risk of the first die body 114 and the second die body 116 separating under pressure at the manifold back line, and prevents leakage from developing between the first die body 114 and the second die body 116 at the manifold back line.

[0034] The front line 128b of the primary manifold 128 may taper toward the back line 128a as the front line 128b extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The primary manifold 128 may have a dimension d8, such as length, along a first direction D1 from the back line 128a to the front line 128b, wherein the length d8 decreases as the primary manifold 128 extends toward the first end 106 and the second end 108. Thus, the length d8 may be greater toward the center of the primary manifold 128 than toward the first end 106 and the second end 108. The primary manifold 128 may also have a dimension d9, such as height or depth, along a third direction D3. The height or depth d9 may decrease as the primary manifold 128 extends toward the first end 106 and the second end 108. It should be understood that, in alternative examples, the primary manifold 128 may have any other suitable shape in a cross-sectional plane perpendicular to the third direction D3, such as a coat hanger shape and a T-shape.

[0035] refer to Figure 6 and Figure 7The primary manifold 128 may have a back end 128c and a front end 128d in its cross-section. In some examples, the height or depth d9 of the primary manifold 128 at the back end 128c may be substantially uniform or constant in the cross-sectional plane as the back end 128c extends toward the front end 128d. The front end 128d may taper inward in the cross-sectional plane as it extends from the back end 128c toward the front line 128b of the primary manifold 128. Thus, the height or depth d9 may decrease as the front end 128d extends from the back end 128c toward the front line 128b.

[0036] For more specific reference Figure 8 The diagram shows an enlarged view of a primary manifold 128 according to an example. A first manifold body 114 may have a back end inner surface 129a and a front end inner surface 129b extending from the back end inner surface 129a toward the front line 128b. The back end inner surface 129a and the front end inner surface 129b define a first side of the primary manifold 128. Similarly, a second manifold body 116 may have a back end inner surface 131a and a front end inner surface 131b extending from the back end inner surface 131a toward the front line 128b. The back end inner surface 131a and the front end inner surface 131b define a second side of the primary manifold 128. The back end inner surface 129a and the front end inner surface 129b may be opposite the back end inner surface 131a and the front end inner surface 131b, respectively, to define the primary manifold 128 therebetween. The height or depth d9 of the primary manifold 128 from the inner surface 129a to the inner surface 131a of the back end in the cross-sectional plane can be constant along the first direction D1. The inner surface 129b and the inner surface 131b of the front end can converge toward each other as they extend from the inner surface 129a and the inner surface 131a of the back end toward the front line 128b, respectively.

[0037] The front inner surface 129b may have a first bend 129c extending from the back inner surface 129a toward the front line 128b. The first bend 129c may be concave inward toward the second die body 116 as it extends toward the front line 128b (as observed from the inside of the primary manifold 128). The first bend 129c may have a radius of curvature that varies as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. For example, the radius of curvature of the first bend 129c may increase as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. In an alternative example, the radius of curvature may be constant as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The range of the radius of curvature can be from... Up to (depth d9×10).

[0038] The front inner surface 129b may have a second bend 129d extending from the front line 128b toward the back inner surface 129a. The second bend 129d may bend outwardly away from the second die body 116 as it extends toward the back line 128a (as observed from the inside of the primary manifold 128). The second bend 129d may have a radius of curvature that varies as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. For example, the radius of curvature of the second bend 129d may increase as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. In an alternative example, the radius of curvature may be constant as the second bend 129d extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The range of the radius of curvature can be from... Up to (depth d9×25).

[0039] In some examples, the first bend 129c and the second bend 129d may be tangent to each other. In some examples, the first bend 129c and the second bend 129d may be adjacent to each other, such that the front end inner surface 129b bends continuously from the back end inner surface 129a to the front line 128b without any linear portion extending from the first bend 129c to the second bend 129d. In other examples, the front end inner surface 129b may include a linear portion 129e extending from the first bend 129c to the second bend 129d. In some examples, the length of the front end inner surface 129b from the back end inner surface 129a to the front line 128b is linear for no more than one-third of the time.

[0040] Similarly, the front inner surface 131b may have a first bend 131c extending from the back inner surface 131a toward the front line 128b. The first bend 131c may bend inward toward the first die body 114 as it extends toward the front line 128b (as observed from the inside of the primary manifold 128). The first bend 131c may have a radius of curvature that varies as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. For example, the radius of curvature of the first bend 131c may increase as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. In an alternative example, the radius of curvature may be constant as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The range of the radius of curvature can be... Up to (depth d9×10).

[0041] The front inner surface 131b may have a second bend 131d extending from the front line 128b toward the back inner surface 129a. The second bend 131d may bend outwardly away from the first die body 114 as it extends toward the back line 128a (as observed from the inside of the primary manifold 128). The second bend 131d may have a radius of curvature that varies as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. For example, the radius of curvature of the second bend 131d may increase as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. In an alternative example, the radius of curvature may be constant as the second bend 131d extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The range of the radius of curvature can be... Up to (depth d9×25).

[0042] In some examples, the first bend 131c and the second bend 131d may be tangent to each other. In some examples, the first bend 131c and the second bend 131d may be adjacent to each other, such that the front end inner surface 131b bends continuously from the back end inner surface 129a to the front line 128b without any linear portion extending from the first bend 131c to the second bend 131d. In other examples, the front end inner surface 131b may include a linear portion 131e extending from the first bend 131c to the second bend 131d. In some examples, the length of the front end inner surface 131b from the back end inner surface 131a to the front line 128b is linear for no more than one-third of the length.

[0043] Although Figure 8 Examples disclosed are shown as having four bends 129c, 129d, 131c, and 131d, but the examples disclosed herein are not limited thereto. In alternative examples, the primary manifold 128 may have as few as one bend and as many as four bends.

[0044] Brief Reference Figure 9 The image shows an enlarged view of a primary manifold 128 according to another example. In this example, it is similar to... Figure 8 For example, the first mold body 114 may have a back end inner surface 129a and a front end inner surface 129b, and the second mold body 116 may have a back end inner surface 131a and a front end inner surface 131b. The back end inner surfaces 129a and 131a can be constructed as discussed above. However, with the front end inner surfaces 129b and 131b being curved... Figure 8 The primary manifold 128 is different. Figure 9The primary manifold 128 has angled front inner surfaces 129b and 131b. Specifically, the front inner surfaces 129b and 131b are linear as they extend from the rear inner surfaces 129a and 131a, respectively, towards the front line 128b of the primary manifold 128. The front inner surfaces 129b and 131b may converge toward each other as they extend from the rear inner surfaces 129a and 131a toward the front line 128b, respectively. The front inner surfaces 129b and 131b may terminate at lines 129f and 131f, respectively, at the rear inner surfaces 129a and 131a. Furthermore, the front inner surfaces 129b and 131b may terminate at lines 129g and 131g, respectively, at the front line 128b.

[0045] Line 129f may define a vertex between the back end inner surface 129a and the front end inner surface 129b. An angle α1 may be defined between the back end inner surface 129a and the front end inner surface 129b. Angle α1 may vary as the back end inner surface 129a and the front end inner surface 129b extend outward toward the first end 106 and the second end 108 of the extrusion die 100. For example, angle α1 may increase as the back end inner surface 129a and the front end inner surface 129b extend outward toward the first end 106 and the second end 108 of the extrusion die 100. Alternatively, angle α1 may remain constant as the back end inner surface 129a and the front end inner surface 129b extend outward toward the first end 106 and the second end 108 of the extrusion die 100.

[0046] Line 131f may define a vertex between the inner surface 131a of the back end and the inner surface 131b of the front end. An angle α2 may be defined between the inner surface 131a of the back end and the inner surface 131b of the front end. Angle α2 may vary as the inner surfaces 131a of the back end and 131b of the front end extend outward toward the first end 106 and the second end 108 of the extrusion die 100. For example, angle α2 may increase as the inner surfaces 131a of the back end and 131b of the front end extend outward toward the first end 106 and the second end 108 of the extrusion die 100. Alternatively, angle α2 may remain constant as the inner surfaces 131a of the back end and 131b of the front end extend outward toward the first end 106 and the second end 108 of the extrusion die 100.

[0047] Line 129g may have a vertex defined at the end of the front inner surface 129b opposite to line 129f, such as between the front inner surface 129b and the surface defining the next chamber. An angle α3 may be defined between the front inner surface 129b and the surface defining the next chamber. Angle α3 may vary as the front inner surface 129b extends outward toward the first end 106 and the second end 108 of the extrusion die 100. For example, angle α3 may increase as the front inner surface 129b extends outward toward the first end 106 and the second end 108 of the extrusion die 100. Alternatively, angle α3 may remain constant as the front inner surface 129b extends outward toward the first end 106 and the second end 108 of the extrusion die 100.

[0048] Line 131g may have a vertex defined at the end of the front inner surface 131b opposite to line 131f, such as between the front inner surface 131b and the surface defining the next chamber. An angle α4 may be defined between the front inner surface 131b and the surface defining the next chamber. Angle α4 may vary as the front inner surface 131b extends outward toward the first end 106 and the second end 108 of the extrusion die 100. For example, angle α4 may increase as the front inner surface 131b extends outward toward the first end 106 and the second end 108 of the extrusion die 100. Alternatively, angle α4 may remain constant as the front inner surface 131b extends outward toward the first end 106 and the second end 108 of the extrusion die 100.

[0049] Angled to the front inner surfaces 129b and 131b Figure 9 Compared to the primary manifold 128 in the example, Figure 8 The primary manifold 128, with its curved inner front surfaces 129b and 131b, can induce smaller shear changes in the fluid as it flows through it. This, in turn, can result in a more uniform flow orientation of the fluid in its further trajectory within and even outside the extrusion die 100. Implementing bends 129c, 129d, 131c, and 131d allows for greater flexibility in manifold shape design and enables a more uniform fluid distribution across the width of the extrusion die 100, resulting in less shear introduced into the fluid. It should be understood that virtually any primary manifold design, whether previously disclosed or not, can be similar to... Figure 8 The example is implemented using a curved front end surface. This can be done without any restrictions on the shape of the manifold or the shape of the preform (discussed further below). Furthermore, the curved front end surface can be applied to coat hanger manifolds, T-shaped manifolds, manifolds with straight back lines, manifolds with inverted preforms, or any other suitable manifold shape.

[0050] Re-reference Figures 3 to 5 The extrusion cavity 118 of the extrusion die 100 may optionally include an intermediate chamber 130 extending along a first direction D1 from the primary manifold 128 toward the outlet 122. The intermediate chamber 130 may be in fluid communication with the primary manifold 128 and the inlet 120. The intermediate chamber 130 may have a back line 130a and a front line 130b offset from each other along the first direction D1. The back line 130a may coexist with the front line 128b of the primary manifold 128. The back line 130a may taper away from the front line 130b as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. Similarly, the front line 130b may taper away from the back line 130a as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. As a result, the intermediate chamber 130 can have a bow-shaped cross-section in a plane perpendicular to the third direction D3. The intermediate chamber 130 can have a dimension d along the first direction from the back line 130a to the front line 130b. 10 Such as length, where length d 10 The length d increases as the intermediate chamber 130 extends toward the first end 106 and the second end 108. 10 It can be oriented towards the first end 106 and the second end 108 larger than it is oriented towards the center of the primary manifold 128.

[0051] refer to Figure 6 and Figure 7 The cross-section of the intermediate chamber 130 may also have a gap, which has a dimension d along the third direction D3. 11 Size d 11 It can remain constant as the intermediate chamber 130 extends toward the first end 106 and the second end 108. Dimension d 11 It can be smaller than the height or depth d9 of the primary manifold 128. Dimension d 11 The intermediate chamber 130 can remain constant as it 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 can have a front end that tapers inward as it extends along the first direction to the front line 130b, such that the dimension d 11 Reduced to the size of the preform 132.

[0052] In conventional extrusion dies with primary manifolds featuring linear backlines, the primary manifold channels may be too large in volume towards the end of the extrusion die. This can result in long polymer residence times. Figures 3 to 5In this design, the intermediate chamber 130 can reduce the volume of the primary manifold 128 toward each of the first end 106 and the second end 108 of the extrusion die 100. Because the front line 128b of the primary manifold 128 tapers upstream toward each of the first end 106 and the second end 108 of the extrusion die 100, the length d8 of the primary manifold 128 toward the first end 106 and the second end 108 can be less than the length toward the first and second ends of a comparable conventional extrusion die 100 with a primary manifold having a linear backline. Furthermore, the height or depth d9 of the primary manifold 128 can also taper as it extends toward each of the first end 106 and the second end 108. This can further reduce the volume at the first end 106 and the second end 108 compared to a comparable conventional extrusion die 100. The intermediate chamber 130 can facilitate a more uniform distribution of fluid along the second direction D2 across the width of the extrusion die 100.

[0053] Re-reference Figures 3 to 5 The extrusion cavity 118 of the extrusion die 100 may include a preform 132 extending along a first direction D1 from an intermediate cavity 130 toward an outlet 122. The preform 132 is in fluid communication with the intermediate cavity 130 and thus with the primary manifold 128 and the inlet 120. It should be noted that in alternative examples where the intermediate cavity 130 is not implemented, the preform 132 may extend along the first direction D1 from the primary manifold 128 toward the outlet 122, such as... Figure 10 and Figure 14 As shown in the figure, the preformed part 132 can be in fluid communication with the primary manifold 128.

[0054] The preform 132 may have a back line 132a and a front line 132b offset from each other along a first direction D1. The back line 132a may coexist with the front line 130b of the intermediate chamber 130 or the front line 128b of the primary manifold 128 (in an example where the intermediate chamber 130 is not implemented). The back line 132a may taper toward the front line 132b as the back line 132a extends outward toward the first end 106 and the second end 108 of the extrusion die 100. At least a portion, and indeed the entirety, of the front line 132b may be linear along a second direction D2 as the front line 132b extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The front line 132b may be substantially parallel to the outlet 122. Thus, the preform 132 may have a substantially triangular cross-sectional shape in a plane perpendicular to a third direction D3. The preformed portion 132 may have a dimension d along a first direction from the back line 132a to the front line 132b. 12 Such as length, where length d 12 The length d decreases as the intermediate chamber 130 extends toward the first end 106 and the second end 108. 10The diameter of the first end 106 and the second end 108 can be smaller than that of the center of the preform 132.

[0055] Typically, as the fluid fans out towards the first end 106 and the second end 108, there is a pressure drop from the center of the primary manifold 128. The preform 132 is configured to be longer toward the center of the extrusion die 100 in order to reduce pressure near the center and thereby make the pressure more uniform across the width of the extrusion die 100. The preform 132 should preferably be configured such that the velocity, pressure, and shear of the fluid material at the ends of the preform 132 are each uniform along the second direction D2 across the width of the extrusion die 100.

[0056] refer to Figure 6 and Figure 7 The preformed portion 132 can define a preformed portion gap, the preformed portion gap having a dimension d along the third direction D3. 13 Such as height or depth. Height or depth d 13 It can remain constant as the preform 132 extends toward the first end 106 and the second end 108. Alternatively, the height or depth d 13 The height or depth d can be increased as the preformed portion 132 extends toward the first end 106 and the second end 108. 13 It can be smaller than the size d of the intermediate chamber, which is 130. 11 And the height or depth d9 of the primary manifold 128. Height or depth d 13 The preformed portion 132 can remain constant as it extends along the first direction D1 between the back line 132a and the front line 132b. However, it should be noted that the preformed portion 132 can taper outward at its front end to the front line 132b to abut the secondary manifold 134.

[0057] Re-reference Figures 3 to 5 The extrusion cavity 118 of the extrusion die 100 may include a secondary manifold 134, also referred to as a melt well, which extends along a first direction D1 from the preform section 132 toward the outlet 122. The secondary manifold 134 may be in fluid communication with the preform section 132, and thus with the intermediate chamber 130, the primary manifold 128, and the inlet 120. The secondary manifold 134 may have a back line 134a and a front line 134b that are offset from each other along the first direction D1. The back line 134a may coexist with the front line 132b of the preform section 132.

[0058] At least a portion, and indeed the entirety, of the back line 134a may be linear along a second direction D2 as the back line 134a extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The back line 134a may be substantially parallel to the outlet 122. Similarly, at least a portion, and indeed the entirety, of the front line 134b may be linear along a second direction D2 as the front line 134b extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The front line 134b may be substantially parallel to the outlet 122. Therefore, the secondary manifold 134 may have a rectangular cross-sectional shape in a plane perpendicular to a third direction D3. The secondary manifold 134 may have a dimension d along a first direction from the back line 134a to the front line 134b. 14 Such as length, where length d 14 The length d remains constant as the secondary manifold 134 extends toward the first end 106 and the second end 108. 14 The same can be achieved at the center of the secondary manifold 134 and at the first end 106 and the second end 108. When implementing the intermediate chamber 130, the preform 132 can be implemented as shown, such that the apex of the triangular shape points towards the inlet, and the leading line 132b of the preform 132 can be substantially parallel to the outlet 122. This allows the secondary manifold 134 to have a rectangular shape, which facilitates a more linear fluid flow across the width of the secondary manifold 134 and towards the outlet 122 in the first direction D1. This is in contrast to conventional extrusion dies with an inverted preform (i.e., the apex of the triangular shape points towards the outlet). In such conventional dies, the inverted preform causes the secondary manifold to vary in size from the center of the die to the end of the die. This, in turn, can lead to lateral fluid flow within the secondary manifold (i.e., fluid flow along the second direction D2) when lateral fluid flow is not desired.

[0059] refer to Figure 6 and Figure 7 The cross-section of the secondary manifold 134 can have a dimension d along the third direction D3. 15 Such as height or depth. Height or depth d 15 It can remain constant as the secondary manifold 134 extends toward the first end 106 and the second end 108. Height or depth d 15 It can be greater than the height or depth d of the preform 132. 13 In some examples, height or depth d 15 It can be larger than the size d of the intermediate chamber by 130. 11 Height or depth d 15The secondary manifold 134 can be kept constant as it extends along the first direction D1 between the back lines 134a toward the front line 134b. However, it should be noted that the secondary manifold 134 can taper inward at its tip toward the front line 134b to abut the outlet 122. The secondary manifold 134 is configured to have a greater height or depth than the preform 132, such that the secondary manifold 134 acts to slow down the fluid velocity. This slowing down reduces the pressure of the fluid on the first lip 124 and the second lip 126, which, under other circumstances, could cause the first lip 124 and the second lip 126 to deflect away from each other.

[0060] Re-reference Figures 3 to 5 The extrusion cavity 118 of the extrusion die 100 may include an outlet 122 extending from the secondary manifold 134 away from the inlet 120 along a first direction D1. The outlet 122 may be in fluid communication with the secondary manifold 134, and thus with the preform section 132, the intermediate chamber 130, the primary manifold 128, and the inlet 120. The outlet 122 may have a back line 122a and a front line 122b offset from each other along the first direction D1. The back line 122a may coexist with the front line 132b of the secondary manifold 134. At least a portion, and indeed the entirety, of the back line 122a may be linear along a second direction D2 as the back line 122a extends outward toward the first end 106 and the second end 108 of the extrusion die 100. Similarly, at least a portion, and indeed the entirety, of the front line 122b can be linear along the second direction D2 as the front line 122b extends outward toward the first end 106 and the second end 108 of the extrusion die 100. As a result, the outlet 122 can have a rectangular cross-sectional shape in a plane perpendicular to the third direction D3. The outlet 122 can have a dimension d along the first direction from the back line 122a to the front line 122b. 16 Such as length, where length d 16 As outlet 122 extends towards the first end 106 and the second end 108, the length d remains constant. 16 It can be the same at the center of outlet 122 and at the first end 106 and the second end 108.

[0061] refer to Figure 6 and Figure 7 The cross-section of the outlet 122 can be defined along the third direction D3 with a gap of size d5. Size d5 can be smaller than the size d of the secondary manifold 134. 15 In some examples, the dimension d5 can be smaller than the height or depth d of the preform 132. 13The outlet 122 may be defined by a first lip 124 of a first die body 114 and a second lip 126 of a second die body 116. In some examples, the first die body 114 may include a hinge 125 configured to flex to move at least a portion of the first lip 124 toward or away from the second lip 126 along a third direction D3 to fine-tune the dimension d5. Although not shown, a plurality of adjusters may be spaced apart from each other along a second direction D2, wherein each adjuster is configured to engage the first lip 124 to move a different portion of the second lip 126 along the third direction D3. The first lip 124 may be configured to be adjusted by the adjusters to change the dimension d5 along the second direction D2 to obtain a desired profile of the extruded sheet. Thus, the first lip 124 may be considered a flexible lip. On the other hand, the second lip 126 may be a fixed lip that does not move relative to the rest of the second die body 116.

[0062] refer to Figure 10 and Figure 12 The image shows an extrusion die 100' according to another example. The extrusion die 100' has several features similar to those described above. Figures 1 to 9 The features discussed in the extrusion die 100. Therefore, the same features are labeled with the same reference numerals, and the above description of those features also applies. Figures 10 to 12 The corresponding features. In this example, the extrusion die 100' defines an extrusion cavity 118, which includes an inlet 120, a primary manifold 128', a preform section 132, a secondary manifold 134, and an outlet 122. The inlet 120, the preform section 132, the secondary manifold 134, and the outlet 122 can be as described above regarding... Figures 1 to 9 The extrusion die 100 is constructed as discussed. However, the extrusion die 100' does not... Figures 1 to 9 The intermediate chamber 130, leading to Figures 10 to 12 The primary manifold 128' with front 128b' has a slightly different design. Figures 1 to 9 The structure of the primary manifold 128.

[0063] Specifically, the front line 128b' may taper away from the back line 128a as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. In some examples, the front line 128b' may be linear as it extends toward the first end 106 and as it extends toward the second end 108. In other examples (not shown), the front line 128b' may be curved toward the back line 128a as it extends toward the first end 106 to form an arc of a first circle, and as it extends toward the second end 108 to form an arc of a second circle. The primary manifold 128 may have a dimension d8, such as a length, along a first direction from the back line 128a to the front line 128b', wherein the length d8 increases as the primary manifold 128' extends toward the first end 106 and the second end 108. Therefore, the length d8 can be greater toward the first end 106 and the second end 108 than it is toward the center of the primary manifold 128'. Apart from the different construction of the front end 128b', the primary manifold 128' can have a rear end 128c and a front end 128d constructed as discussed above, and can have the same characteristics as described above. Figure 8 or Figure 9 The similar cross sections discussed.

[0064] Now for reference Figures 13 to 16 The diagram shows yet another example of an extrusion die 100. The extrusion die 100 has several features similar to those described above. Figures 1 to 9 The features discussed in the extrusion die 100. Therefore, the same features are labeled with the same reference numerals, and the above description of those features also applies. Figures 13 to 16 The corresponding features. In this example, the extrusion die 100” defines an extrusion cavity 118, which includes an inlet 120, a primary manifold 128”, a preform section 132”, a secondary manifold 134”, and an outlet 122. The inlet 120 and outlet 122 can be as described above regarding... Figures 1 to 9 The extrusion die 100 is constructed as discussed. However, the extrusion die 100 does not... Figures 1 to 9 The intermediate chamber 130, and the primary manifold 128", the preformed section 132", and the secondary manifold 134" respectively have with Figures 1 to 9 The primary manifold 128, the preform section 132, and the secondary manifold 134 have different structures. Furthermore, the first recess and the second recess (which together define the extrusion cavity 118) defined in the first die body 114 and the second die body 116 are different from each other and are therefore not mirror images of each other.

[0065] "Primary manifold 128" can include similar features to those mentioned above. Figures 1 to 9The discussion focuses on the linear back line 128a. However, the front line 128b” of the primary manifold 128” can also be linear along the second direction D2 as the front line 128b” extends outward toward the first end 106 and the second end 108 of the extrusion die 100”. Thus, the front line 128b” can be substantially parallel to the outlet 122. The primary manifold 128” can have a dimension d8, such as length, along the first direction from the back line 128a to the front line 128b”, wherein the length d8 is constant as the primary manifold 128” extends toward the first end 106 and the second end 108. The primary manifold 128” can have a similar dimension as described above regarding the back line 128a. Figures 1 to 9 The cross sections of those discussed.

[0066] The preform 132” may have a back line 132a”, which is linear along a second direction D2 as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100”. Therefore, the back line 132a” may be substantially parallel to the outlet 122. The front line 132b” of the preform 132” may taper toward the back line 132a” as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100”. The preform 132” may have a dimension d from the back line 132a” to the front line 132b” along a first direction. 12 Such as length, where length d 12 The length d decreases as the preformed portion 132” extends toward the first end 106 and the second end 108. 12 The center of the preform 132” can be larger than the center of the first end 106 and the second end 108.

[0067] The secondary manifold 134” may have a back line 134a” that tapers away from the front line 134b” as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. The front line 134b” may be linear along a second direction D2 as it extends outward toward the first end 106 and the second end 108 of the extrusion die 100. Thus, the front line 134b” may be substantially parallel to the outlet 122. The secondary manifold 134” may have a dimension d along the first direction from the back line 134a” to the front line 134b”. 14 Such as length, where length d 14 The length d increases as the secondary manifold 134” extends toward the first end 106 and the second end 108. 14 It can be larger toward the first end 106 and the second end 108 than it is at the center of the secondary manifold 134".

[0068] like Figure 15 and Figure 16As shown, the extrusion cavity 118 may have a first side defined by a first die head body 114 and a second side defined by a second die head body 116 that is opposed to the first side in a third direction. The first side may be substantially planar across the preform section 132”, the secondary manifold 134”, and the outlet 122, while the depth of the second side may vary across the preform section 132”, the secondary manifold 134”, and the outlet 122.

[0069] The following are several non-limiting examples of aspects of this disclosure. One example includes: Example 1. An extrusion die, a first die body and a second die body defining an extrusion cavity therebetween, the extrusion cavity having: an inlet; a primary manifold extending from the inlet in a flow direction, the primary manifold having a back line and a front line, the front line being spaced apart from the back line in the flow direction, the back line being substantially linear in a second direction as it extends outward toward the extrusion die toward a first end and a second end spaced apart from each other in a second direction perpendicular to the flow direction, the front line tapering toward the back line as it extends outward toward the first end and the second end; an intermediate chamber extending from the primary manifold. Extending along the flow direction, the intermediate chamber has a back line and a front line, the back line of the intermediate chamber extending together with the front line of the primary manifold, the front line of the intermediate chamber being 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 in a third direction perpendicular to the flow direction and the second direction, the depth of the intermediate chamber being less than the depth of the primary manifold; and an outlet in fluid communication with the primary manifold and the intermediate chamber, the outlet defining a slot elongated along the second direction.

[0070] The above embodiments may further include any one or a combination of the following examples: 2. An extrusion die according to any example herein, wherein the intermediate cavity has a bow-shaped cross-section in a plane perpendicular to the third direction. 3. An extrusion die according to any example herein, wherein the extrusion cavity includes a preformed portion having a preformed portion back line and a preformed portion front line, the preformed portion front line being offset from the preformed portion back line along the flow direction, the preformed portion back line coexisting with the front line of the intermediate cavity, and the preformed portion back line tapering toward the preformed portion front line as the preformed portion back line extends outward toward the first and second ends of the extrusion die, the depth of the preformed portion along the third direction being less than the depth of the intermediate cavity. 4. An extrusion die according to any example herein, wherein the preformed portion front line is linear along the second direction as the preformed portion front line extends outward toward the first and second ends of the extrusion die (100). 5. According to any example of the extrusion die herein, the extrusion cavity includes a secondary manifold having a back line and a front line, the front line of the secondary manifold being offset from the back line of the secondary manifold along the flow direction, the back line of the secondary manifold being co-extended with the front line of the preform, and the front line and the back line of the secondary manifold being linear along the second direction as they extend outward toward the first and second ends of the extrusion die, the depth of the secondary manifold along the third direction being greater than the depth of the preform. 6. An extrusion die according to any example herein, wherein the primary manifold has a back end and a front end, the front end extending from the back end along the flow direction, the front end being defined by opposing front end inner surfaces of the first die body and the second die body, at least one of the opposing front end inner surfaces tapering toward the other as it extends along the flow direction, the at least one of the opposing front end inner surfaces having a first bend and a second bend, wherein the first bend extends from the back end toward the front line of the primary manifold, and the second bend extends from the front line of the primary manifold toward the back end. 7. An extrusion die according to any example herein, wherein the first bend bends inwardly toward the extrusion cavity as it extends toward the front line. 8. An extrusion die according to any example herein, wherein the first bend has a radius of curvature that varies as the first bend extends outward toward the first end and the second end of the extrusion die. 9. An extrusion die according to any example herein, wherein the radius of curvature of the first bend increases as the first bend extends outward toward the first end and the second end of the extrusion die.10. An extrusion die according to any example of this document, wherein the second bend bends outwardly away from the extrusion cavity as the second bend extends toward the back end of the primary manifold. 11. An extrusion die according to any example of this document, wherein the second bend is capable of having a radius of curvature that varies as the second bend extends outward toward the first and second ends of the extrusion die. 12. An extrusion die according to any example of this document, wherein the radius of curvature of the second bend increases as the second bend extends outward toward the first and second ends of the extrusion die. 13. An extrusion die according to any example of this document, wherein the first bend and the second bend are tangent to each other. 14. An extrusion die according to any example of this document, wherein the first bend and the second bend are adjacent to each other such that the inner surface of the front end bends continuously from the back end to the front line of the primary manifold without any linear portion extending from the first bend to the second bend. 16. An extrusion die according to any example herein, wherein the dimension of the front end surface extending from the back end surface to the front line of the primary manifold is not more than one-third linear. 15. An extrusion die according to any example herein, wherein the inner surface of the front end includes a linear portion extending from the first bend to the second bend.

[0071] One example includes Example 17. An extrusion die includes a first die body and a second die body defining an extrusion cavity therebetween, the extrusion cavity having: an inlet; a primary manifold extending from the inlet in a flow direction, the primary manifold having a back end and a front end, the front end extending from the back end in the flow direction, the front end being defined by opposing front end inner surfaces of the first die body and the second die body, at least one of the opposing front end inner surfaces tapering toward the other as it extends in the flow direction, the at least one of the opposing front end inner surfaces having a first bend and a second bend, wherein the first bend extends from the back end toward the front line of the primary manifold, and the second bend extends from the front line toward the back end; and an outlet in fluid communication with the primary manifold in the flow direction, and the outlet defining a slot elongated in the second direction.

[0072] The above embodiments may further include any one or a combination of more than one of the following examples: 18. An extrusion die according to any example herein, wherein the first bend is concavely bent toward the extrusion cavity as the first bend extends toward the front line. 19. An extrusion die according to any example herein, wherein the first bend has a radius of curvature that varies as the first bend extends outward toward the first and second ends of the extrusion die. 20. An extrusion die according to any example herein, wherein the radius of curvature of the first bend increases as the first bend extends outward toward the first and second ends of the extrusion die. 21. An extrusion die according to any example herein, wherein the second bend is convexly bent away from the extrusion cavity as the second bend extends toward the back end of the primary manifold. 22. An extrusion die according to any example herein, wherein the second bend is capable of having a radius of curvature that varies as the second bend extends outward toward the first and second ends of the extrusion die. 23. An extrusion die according to any example herein, wherein the radius of curvature of the second bend increases as the second bend extends outward toward the first and second ends of the extrusion die. 24. An extrusion die according to any example herein, wherein the first bend and the second bend are tangent to each other. 25. An extrusion die according to any example herein, wherein the first bend and the second bend are adjacent to each other such that the inner surface of the front end bends continuously from the back end to the front line of the primary manifold without any linear portion extending from the first bend to the second bend. 27. An extrusion die according to any example herein, wherein the dimension of the front end surface extending from the back end surface to the front line of the primary manifold is not more than one-third linear. 26. An extrusion die according to any example herein, wherein the inner surface of the front end includes a linear portion extending from the first bend to the second bend.

[0073] It should be noted that the illustrations and descriptions of the examples shown are for illustrative purposes only and should not be construed as limiting this disclosure. Those skilled in the art will understand that various examples are contemplated in this disclosure. Furthermore, it should be understood that the concepts described above through the examples can be used alone or in combination with any of the other examples described above. It should be further understood that the various alternative examples described above with respect to one illustrated example are applicable to all examples as described herein, unless otherwise stated.

[0074] Conditional language used herein, such as “can,” “able,” “may,” “e.g.,” unless otherwise specifically stated or understood in the context, is generally intended to convey that certain embodiments include certain features, elements, and / or steps that are not included in other embodiments. Therefore, such conditional language is not generally intended to imply that features, elements, and / or steps are required in any way by one or more examples or that one or more examples necessarily include such features, elements, and / or steps. The terms “comprising,” “including,” “having,” etc., are synonymous and used inclusively in an open-ended manner, and do not exclude additional elements, features, behaviors, operations, etc.

[0075] While certain examples have been described, these examples are presented by way of illustration only and are not intended to limit the scope of the invention disclosed herein. Therefore, nothing in the foregoing description is intended to imply that any particular feature, characteristic, step, module, or block is necessary or indispensable. Indeed, the novel methods and systems described herein can be embodied in many other forms; and various omissions, substitutions, and variations in the form of the methods and systems described herein can be made without departing from the spirit of the inventions disclosed herein. The appended claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of certain inventions disclosed herein.

[0076] It should be understood that the steps of the exemplary methods described herein are not necessarily required to be performed in the order described, and the order of steps in such methods should be understood as merely exemplary. Similarly, additional steps may be included in such methods, and certain steps may be omitted or combined in methods consistent with various embodiments of the present invention.

[0077] Although the elements (if any) in the method claims below are described in a particular order by corresponding references, those elements are not necessarily intended to be implemented in that particular order unless the description of the claims otherwise implies a particular order for implementing some or all of those elements.

[0078] It should be understood that the use of "a" or "an" to describe features such as components or steps herein does not exclude additional features or multiples of features. For example, a reference to a device having or defining "an" feature does not exclude that the device has or defines more than one feature, provided that the device has or defines at least one feature. Similarly, a reference to "an" of a plurality of features herein does not exclude that the invention includes two or more, up to all of the features. For example, a reference to a device having or defining "one of X and Y" does not prevent the device from having both X and Y.

Claims

1. An extrusion die comprising: a first die body and a second die body defining an extrusion cavity therebetween, the extrusion cavity having: an inlet; a primary manifold extending from the inlet in a flow direction, the primary manifold having a back line and a front line, the front line being spaced apart from the back line in the flow direction, the back line being linear in a second direction perpendicular to the flow direction as the back line extends outwardly toward first and second ends of the extrusion die that are spaced apart from each other in the second direction, the front line tapering toward the back line as the front line extends outwardly toward the first and second ends; an intermediate chamber extending from the primary manifold in the flow direction, the intermediate chamber having a back line and a front line, the back line of the intermediate chamber being coextensive with the front line of the primary manifold, the front line of the intermediate chamber being spaced apart from the back line of the intermediate chamber in the flow direction, the front line of the intermediate chamber tapering away from the back line of the intermediate chamber as the front line of the intermediate chamber extends outwardly toward the first and second ends, and the intermediate chamber having a depth in a third direction perpendicular to the flow direction and the second direction, the depth of the intermediate chamber being less than a depth of the primary manifold; an outlet in fluid communication with the primary manifold and the intermediate chamber, the outlet defining a slot that is elongated in the second direction. The intermediate chamber has a bowtie cross-sectional shape in a plane perpendicular to the third direction.

2. The extrusion die of claim 1, wherein, The extrusion cavity includes a preform portion having a preform portion back line and a preform portion front line, the preform portion front line being offset from the preform portion back line in the flow direction, the preform portion back line being coextensive with the front line of the intermediate chamber, and the preform portion back line tapering toward the preform portion front line as the preform portion back line extends outwardly toward first and second ends of the extrusion die, the preform portion having a depth in the third direction that is less than the depth of the intermediate chamber.

3. The extrusion die of claim 1 or 2, wherein, The preform portion front line is linear in the second direction as the preform portion front line extends outwardly toward first and second ends of the extrusion die.

4. The extrusion die of claim 3, wherein, The extrusion cavity includes a secondary manifold having a back line and a front line, the front line of the secondary manifold being offset from the back line of the secondary manifold in the flow direction, the back line of the secondary manifold being coextensive with the front line of the preform portion, and the front and back lines of the secondary manifold each being linear in the second direction as they extend outwardly toward first and second ends of the extrusion die, the secondary manifold having a depth in the third direction that is greater than the depth of the preform portion.

5. The extrusion die of claim 4, wherein, ​ 6. The extrusion die of claim 1 or 2, wherein, The primary manifold has a back end and a front end extending from the back end in the flow direction, the front end being defined by opposing front inner surfaces of the first die body and the second die body, respectively, at least one of the opposing front inner surfaces tapering toward the other of the front inner surfaces as it extends in the flow direction, the at least one of the opposing front inner surfaces having a first curved portion and a second curved portion, the first curved portion extending from the back end toward a front line of the primary manifold, and the second curved portion extending from the front line toward the back end.

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

8. The extrusion die of claim 6, wherein, The radius of curvature of the first curved portion varies as the first curved portion extends outward toward the first end and the second end of the extrusion die.

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

10. The extrusion die of claim 6, wherein, The second curved portion curves convexly outward away from the extrusion cavity as the second curved portion extends toward the back end of the primary manifold.

11. The extrusion die of claim 10, wherein, The radius of curvature of the second curved portion varies as the second curved portion extends outward toward the first end and the second end of the extrusion die.

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

13. The extrusion die of claim 6, wherein, The first curved portion and the second curved portion are tangent to each other.

14. The extrusion die of claim 6, wherein, The first curved portion and the second curved portion are contiguous with each other such that the front inner surface curves continuously from the back end to the front line of the primary manifold without any linear portion extending from the first curved portion to the second curved portion.

15. The extrusion die of claim 6, wherein, The front inner surface includes a linear portion extending from the first curved portion to the second curved portion.

16. The extrusion die of claim 6, wherein, No more than one-third of the front inner surface extending from a back end surface of the primary manifold to the front line of the primary manifold is linear.

17. An extrusion die, comprising: a first die body and a second die body defining an extrusion cavity therebetween, the extrusion cavity having: an inlet; a primary manifold extending from the inlet in a flow direction, the primary manifold having a back end and a front end extending from the back end in the flow direction, the front end being defined by opposing front inner surfaces of the first die body and the second die body, respectively, at least one of the opposing front inner surfaces tapering toward the other of the front inner surfaces as it extends in the flow direction, the at least one of the opposing front inner surfaces having a first curved portion and a second curved portion, the first curved portion extending from the back end toward a front line of the primary manifold, and the second curved portion extending from the front line toward the back end; an intermediate chamber extending from the primary manifold in the flow direction, the intermediate chamber having a back line and a front line, the back line of the intermediate chamber being coextensive with the front line of the primary manifold, the front line of the intermediate chamber being spaced apart from the back line of the intermediate chamber in the flow direction, the front line of the intermediate chamber tapering away from the back line of the intermediate chamber as the front line of the intermediate chamber extends outwardly toward the first end and the second end, and the intermediate chamber having a depth in a third direction that is perpendicular to the flow direction and perpendicular to the flow direction, the depth of the intermediate chamber being less than the depth of the primary manifold; and an outlet in fluid communication with the primary manifold in the flow direction, the outlet defining a slot that is elongated in a direction that is perpendicular to the flow direction.

18. The extrusion die of claim 17, wherein, The first curved portion curves concavely inwardly toward the extrusion cavity as the first curved portion extends toward the front line.

19. The extrusion die of claim 17 or 18, wherein, The radius of curvature of the first curved portion varies as the first curved portion extends outwardly toward the first end and the second end of the extrusion die.

20. The extrusion die of claim 19, wherein, The radius of curvature of the first curved portion increases as the first curved portion extends outwardly toward the first end and the second end of the extrusion die.

21. The extrusion die of claim 19, wherein, The second curved portion curves convexly outwardly away from the extrusion cavity as the second curved portion extends toward the back end portion of the primary manifold.

22. The extrusion die of claim 21, wherein, The radius of curvature of the second curved portion varies as the second curved portion extends outwardly toward the first end and the second end of the extrusion die.

23. The extrusion die of claim 22, wherein, The radius of curvature of the second curved portion increases as the second curved portion extends outwardly toward the first end and the second end of the extrusion die.

24. The extrusion die of claim 17 or 18, wherein, The first curved portion and the second curved portion are tangential to each other.

25. The extrusion die of claim 17 or 18, wherein, The first curved portion and the second curved portion are contiguous with each other such that the front end inner surface curves continuously from the back end portion to the front line of the primary manifold without any linear portion extending from the first curved portion to the second curved portion.

26. The extrusion die of claim 17 or 18, wherein, The front end inner surface includes a linear portion extending from the first curved portion to the second curved portion.

27. The extrusion die of claim 17 or 18, wherein, The front end inner surface extending from the back end surface of the primary manifold to the front line of the primary manifold is linear for no more than one-third of the dimension.

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