Mold assembly for injection molding part

Abstract

The utility model discloses a mold assembly for an injection molding part. The mold assembly comprises a first mold and a second mold, the second mold is connected with the first mold, and a forming space and an injection molding channel communicated with the forming space are formed between the first mold and the second mold; and the convex blocks are arranged on the first mold and / or the second mold, and the convex blocks protrude out of the inner wall of the injection molding channel. According to the mold assembly designed by the utility model, the convex blocks protruding out of the inner wall of the injection molding channel are arranged on the first mold and / or the second mold, and the convex blocks can reduce the sectional area of the injection molding channel, so that different injection molding materials can be quickly and effectively mixed when passing through the convex blocks, and the injection molding materials entering the molding space are mixed more uniformly; bamboo joint lines are prevented from appearing on the surface of the molded injection part, and the appearance of the injection part is beautified.

Description

Technical Field

[0001] The utility model relates to the field of molds, in particular to a mold assembly for injection molded parts. Background Art

[0002] In the related art, most of the rear door exterior panels of vehicles are injection molded. In order to ensure the strength of the product, PC+ABS is generally used as the molding material. When PC+ABS is injection molded, bamboo knots are very likely to appear on the surface of the product at the main gate, which seriously affects the appearance of the product. In the prior art, the injection speed is usually reduced to less than 5% and then other process conditions are adjusted to eliminate the bamboo knot phenomenon. However, if the injection speed is too low, the product will be deformed too much and the heat of the material flow will be lost too quickly. When it merges with the material flow from the second gate, serious temperature difference lines will appear on the surface of the product, affecting the appearance quality of the product. At the same time, if the injection speed is too low, the production cycle will be extended and production efficiency will be reduced. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the utility model is to propose a mold assembly for injection molded parts. According to the mold assembly designed by the utility model, by setting a convex block protruding from the inner wall of the injection channel on the first mold and / or the second mold, the convex block can reduce the cross-sectional area of ​​the injection channel, so that different injection materials can be quickly and effectively mixed when passing through the convex block, so that the injection materials entering the molding space are mixed more evenly, and bamboo knot patterns are avoided on the surface of the injection molded part after molding, which beautifies the appearance of the injection molded part.

[0004] According to the utility model, the mold assembly includes: a first mold; a second mold, the second mold is connected to the first mold, and a molding space and an injection channel connected to the molding space are formed between the first mold and the second mold; a protrusion, the protrusion is arranged on the first mold and / or the second mold, and the protrusion protrudes from the inner wall of the injection channel.

[0005] According to the mold assembly of the utility model, by setting a protrusion on the first mold and / or the second mold, and the protrusion protrudes from the inner wall of the injection channel, the protrusion can reduce the cross-sectional area of ​​the injection channel, so that different injection materials can be quickly and effectively mixed (pressed) when passing through the protrusion, thereby making the injection materials entering the molding space more evenly mixed, avoiding the appearance of bamboo knot patterns on the surface of the injection molded part after molding, beautifying the appearance of the injection molded part, and at the same time, the mold assembly of the present application does not need to reduce the injection speed of the injection material, thereby improving the production efficiency of the injection molded parts.

[0006] According to some embodiments of the utility model, the injection channel includes: a first channel section, which extends in a horizontal direction, one end of which is connected to an injection port, and a height of which gradually decreases in a direction away from the injection port; and a second channel section, which extends in a horizontal direction, one end of which is connected to the other end of the first channel section, and the other end of which is connected to the molding space, and the protrusion is arranged on an inner wall of the second channel section.

[0007] According to some embodiments of the present invention, the protrusion is formed in the first mold, and the height of the protrusion gradually increases in a direction away from the first channel section.

[0008] According to some embodiments of the present invention, the height of the second channel section is h1, which satisfies: 1.5mm≤h1≤1.8mm, and the maximum height of the protrusion is h2, which satisfies: 0.4mm≤h2≤0.6mm.

[0009] According to some embodiments of the present invention, the injection channel also includes: a third channel segment, which is arranged between the second channel segment and the molding space and is suitable for connecting the second channel segment and the molding space, and the third channel segment extends in the height direction.

[0010] According to some embodiments of the present invention, the height of the third channel section is h3, which satisfies: 1.2 mm ≤ h3 ≤ 1.5 mm.

[0011] According to some embodiments of the present invention, an arc-shaped transition section is formed on the second mold, and two ends of the arc-shaped transition section are respectively connected to the second channel section and the third channel section.

[0012] According to some embodiments of the present invention, the width of the first channel section gradually increases in a direction away from the injection port.

[0013] According to some embodiments of the present invention, two side walls of the first channel section in the width direction are respectively a first wall and a second wall, and an angle between the first wall and the second wall is α, satisfying: 40°≤α≤60°.

[0014] According to some embodiments of the present invention, the maximum width dimension of the first channel section is w, which satisfies: 20 mm ≤ w ≤ 30 mm.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0017] Figure 1 is a cross-sectional view of an injection channel of a mold assembly according to an embodiment of the utility model;

[0018] Figure 2 is a top view of an injection channel of a mold assembly according to an embodiment of the utility model;

[0019] Figure 3 It is a schematic diagram of an injection channel of a mold assembly according to an embodiment of the utility model.

[0020] Reference numerals: 1. mold assembly;

[0021] 10. First mold; 11. Bump; 12. Injection port;

[0022] 20. Second mold;

[0023] 31. First channel section; 311. First wall; 312. Second wall; 32. Second channel section; 33. Third channel section. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] In the related art, most of the rear door exterior panels of vehicles are injection molded. In order to ensure the strength of the product, PC+ABS is generally used as the molding material. When PC+ABS is injection molded, bamboo knots are very likely to appear on the surface of the product at the main gate, which seriously affects the appearance of the product. In the prior art, the injection speed is usually reduced to less than 5% and then other process conditions are adjusted to eliminate the bamboo knot phenomenon. However, if the injection speed is too low, the product will be deformed too much and the heat of the material flow will be lost too quickly. When it merges with the material flow from the second gate, serious temperature difference lines will appear on the surface of the product, affecting the appearance quality of the product. At the same time, if the injection speed is too low, the production cycle will be extended and production efficiency will be reduced.

[0030] Reference below Figure 1-Figure 3 A mold assembly 1 for injection molded parts according to an embodiment of the present invention is described.

[0031] like Figure 1-Figure 3 As shown, according to the utility model, the mold assembly 1 includes: a first mold 10, a second mold 20 and a protrusion 11. The second mold 20 is connected to the first mold 10, and a molding space and an injection channel connected to the molding space are formed between the first mold 10 and the second mold 20. The protrusion 11 is arranged on the first mold 10 and / or the second mold 20, and the protrusion 11 protrudes from the inner wall of the injection channel.

[0032] In some embodiments, one of the first mold 10 and the second mold 20 is configured as a movable mold, and the other of the first mold 10 and the second mold 20 is configured as a fixed mold. A molding space is formed between the first mold 10 and the second mold 20. After the injection molding material is molded in the molding space, the movable mold moves in a direction away from the fixed mold to open the molding space, so that the injection molded part can be taken out. An injection channel is also formed between the first mold 10 and the second mold 20, and the injection channel is connected to the molding space. The injection molding material can enter the molding space through the injection channel. An injection port 12 is also formed on the first mold 10 or the second mold 20. The injection port 12 is connected to the injection channel, and the injection molding material can enter the molding space through the injection port 12 and the injection channel in sequence.

[0033] It is understandable that in the injection-molded parts of a vehicle, such as the rear door trim of a vehicle, the injection molding materials include polycarbonate and acrylonitrile-butadiene-styrene copolymer (ABS), and bamboo knots will appear on the surface of the product after molding, seriously affecting the appearance of the product. The bamboo knots are generated because the polycarbonate and acrylonitrile-butadiene-styrene copolymer (ABS) are not mixed evenly in the molding space.

[0034] Therefore, in the mold assembly 1 of the present application, by setting a protrusion 11 on the first mold 10 and / or the second mold 20, and the protrusion 11 protrudes from the inner wall of the injection channel, the protrusion 11 is suitable for reducing the cross-sectional area of ​​the injection channel, so that carbonate (Polycarbonate) and acrylonitrile-butadiene-styrene copolymer (ABS) can be quickly and effectively mixed (pressed) when flowing through the protrusion 11, so that the carbonate (Polycarbonate) and acrylonitrile-butadiene-styrene copolymer (ABS) entering the molding space are mixed more evenly, so that after the injection material is solidified and formed in the molding space, the surface of the injection molded part has no bamboo knot pattern, so that the appearance of the injection molded part is better.

[0035] At the same time, the prior art usually reduces the injection speed of the injection molding material to improve the mixing degree of the injection molding material. In contrast, the present application does not need to reduce the injection speed of the injection molding material, so there is no problem of product deformation due to too low an injection speed, and there will be no problem of severe temperature difference lines on the product surface when merging with the second gate material flow due to too fast heat dissipation of the material flow. At the same time, there will be no problem of extended production cycle and low production efficiency due to too low an injection molding speed.

[0036] It is worth noting that the first mold 10 may be provided with a bump 11, and the bump 11 protrudes from the inner wall of the injection channel; the second mold 20 may be provided with a bump 11, and the bump 11 protrudes from the inner wall of the injection channel; the first mold 10 and the second mold 20 may be provided with bumps 11 respectively, and the bumps 11 on the first mold 10 and the bumps 11 on the second mold 20 respectively protrude from the inner wall of the injection channel, and there is no limitation here.

[0037] It is worth mentioning that the injection channel may extend in the length direction, in which case the protrusion 11 may protrude from the inner wall of the injection channel in the height direction, or the protrusion 11 may protrude from the inner wall of the injection channel in the width direction, which is not limited here.

[0038] According to the mold assembly 1 involved in the utility model, by setting a protrusion 11 on the first mold 10 and / or the second mold 20, and the protrusion 11 protrudes from the inner wall of the injection channel, the protrusion 11 can reduce the cross-sectional area of ​​the injection channel, so that different injection materials can be quickly and effectively mixed (pressed) when passing through the protrusion 11, thereby making the injection materials entering the molding space more evenly mixed, avoiding the appearance of bamboo knot patterns on the surface of the injection molded part after molding, beautifying the appearance of the injection molded part, and at the same time, the mold assembly 1 of the present application does not need to reduce the injection speed of the injection material, thereby improving the production efficiency of the injection molded parts.

[0039] According to some embodiments of the present invention, Figure 1-Figure 3 As shown, the injection channel includes: a first channel section 31 and a second channel section 32, the first channel section 31 extends in the horizontal direction, one end of the first channel section 31 is connected to the injection port 12, the height of the first channel section 31 gradually decreases in the direction away from the injection port 12, the second channel section 32 extends in the horizontal direction, one end of the second channel section 32 is connected to the other end of the first channel section 31, the other end of the second channel section 32 is connected to the molding space, and the protrusion 11 is arranged on the inner wall of the second channel section 32.

[0040] It can be understood that the first channel section 31 and the second channel section 32 are arranged in sequence in the horizontal direction, one end of the first channel section 31 is connected to the injection port 12, the other end of the first channel section 31 is connected to one end of the second channel section 32, and the other end of the second channel section 32 is connected to the molding space, and the injection material passes through the injection port 12, the first channel section 31 and the second channel section 32 in sequence and then enters the molding space.

[0041] It is worth noting that the height of the first channel section 31 gradually decreases in the direction away from the injection port 12, so that the pressure of the injection material gradually increases when flowing through the first channel section 31, thereby increasing the flow rate of the injection material, and at the same time, the injection material can be gradually mixed when flowing through the first channel section 31, so that the injection material entering the second channel section 32 has been preliminarily mixed. The protrusion 11 protrudes from the inner wall of the second channel section 32, that is, the injection material that has been preliminarily mixed can continue to be mixed when passing through the second channel section 32, and when the injection material passes through the protrusion 11, the protrusion 11 can further enhance the mixing efficiency of the injection material, so that the injection material entering the molding space is mixed more evenly.

[0042] According to some embodiments of the present invention, Figure 1-Figure 3 As shown, the protrusion 11 is formed in the first mold 10, and the height of the protrusion 11 gradually increases in the direction away from the first channel section 31. It can be understood that the gradual increase in the height of the protrusion 11 in the direction away from the first channel section 31 makes the transition between the surface of the protrusion 11 and the surface of the second channel section 32 more uniform, avoiding the side wall of the protrusion 11 from blocking the injection molding material when the injection molding material flows in the second channel section 32, improving the passing efficiency of the injection molding material in the second channel section 32, thereby improving the injection molding efficiency, and thus improving the production efficiency of the injection molded parts.

[0043] According to some embodiments of the present invention, Figure 1-Figure 3 As shown, the height of the second channel section 32 is h1, which satisfies: 1.5 mm ≤ h1 ≤ 1.8 mm, and the maximum height of the protrusion 11 is h2, which satisfies: 0.4 mm ≤ h2 ≤ 0.6 mm.

[0044] It is understandable that the height of the second channel section 32 satisfies 1.5mm≤h1≤1.8mm to ensure that different injection molding materials can be effectively mixed when passing through the second channel section 32. Here, the second channel section 32 is provided with a protrusion 11, and the maximum height of the protrusion 11 satisfies 0.4mm≤h2≤0.6mm, so that the height of at least part of the second channel section 32 can be reduced to 0.9mm-1.4mm, thereby improving the mixing efficiency of different injection molding materials when passing through the protrusion 11, thereby improving the mixing degree of the injection molding materials entering the molding space. Preferably, h2=0.5mm.

[0045] It is worth noting that when the bump 11 reduces the height of the second channel section 32 to less than 0.9 mm, the injection molding material will be subjected to a large shear force when passing through the bump 11, thereby causing the temperature of the injection molding material to rise sharply, resulting in deterioration (carbonization) of the injection molding material; when the bump 11 reduces the height of the second channel section 32 to more than 1.4 mm, although the mixing efficiency of the injection molding material is improved when flowing through the bump 11, bamboo knot patterns still exist on the surface of the injection molded part during molding.

[0046] According to some embodiments of the present invention, Figure 1-Figure 3 As shown, the injection channel further includes: a third channel section 33, which is disposed between the second channel section 32 and the molding space and is suitable for connecting the second channel section 32 with the molding space, and the third channel section 33 extends in the height direction.

[0047] It can be understood that the upper inner wall of the first channel section 31 of the present application is in a horizontal state, and the lower inner wall of the first channel section 31 gradually tilts toward the upper inner wall of the first channel section 31 in the direction toward the second channel section 32, and the injection material passes through the injection port 12, the first channel section 31, the second channel section 32 and the third channel section 33 in sequence and then vertically enters the molding space in the height direction. Preferably, the angle between the lower inner wall of the first channel section 31 and the upper inner wall of the first channel section 31 is β, which satisfies: 25°≤β≤30°.

[0048] According to some embodiments of the present invention, Figure 1-Figure 3 As shown, the height of the third channel section 33 is h3, which satisfies: 1.2 mm ≤ h3 ≤ 1.5 mm. It can be understood that, through the above arrangement, the cross-sectional area of ​​the third channel section 33 can be almost equal to the cross-sectional area of ​​the second channel section 32, so that the injection molding material can maintain an efficient mixing state when flowing through the third channel section 33, thereby making the injection molding material more mixed after entering the molding space.

[0049] According to some embodiments of the present invention, Figure 1-Figure 3 As shown, an arc-shaped transition section is formed on the second mold 20, and the two ends of the arc-shaped transition section are connected to the second channel section 32 and the third channel section 33 respectively. It can be understood that the injection material flows in the horizontal direction in the second channel section 32, and the injection material flows vertically upward in the third channel section 33. Therefore, the present application sets an arc-shaped transition section on the second mold 20, and the surface of the arc-shaped transition section is connected to the lower inner wall of the second channel section 32 and the lower inner wall of the third channel section 33 respectively, so as to make the transition between the second channel section 32 and the third channel section 33 better. Therefore, when the injection material flows from the second channel section 32 to the third channel section 33, the arc-shaped transition section can guide the injection material to avoid the lower inner wall of the third channel section 33 from blocking the injection material, thereby ensuring the flow rate of the injection material, improving the efficiency of the injection material entering the molding space, and thus improving the production efficiency of the injection molded parts.

[0050] According to some embodiments of the present invention, Figure 1-Figure 3As shown, the width of the first channel section 31 gradually increases in the direction away from the injection port 12. It can be understood that in the direction away from the first injection port 12, the height of the first channel section 31 gradually decreases, and the lower inner wall of the first channel section 31 gradually extends toward the upper inner wall of the first channel section 31 in the direction toward the second channel section 32, thereby, the lower inner wall of the first channel section 31 can guide the injection material, so that the injection material has a speed toward the upper inner wall of the first channel section 31, so that the injection material has a higher speed in the height direction when entering the third channel section 33, thereby improving the efficiency of the injection material entering the molding space.

[0051] However, since the height of the first channel section 31 gradually decreases in the direction away from the first injection port 12, the speed of the injection molding material will gradually increase when it flows through the first channel section 31, so that the shear force on the injection molding material gradually increases, and the injection molding material will deteriorate (carbonize) when it is subjected to a large shear force. Therefore, the present application makes the width of the first channel section 31 gradually increase in the direction away from the injection port 12 to reduce the shear force on the injection molding material when it flows through the first channel section 31, thereby avoiding the injection molding material from being deteriorated (carbonized) due to the large shear force when it flows through the first channel section 31.

[0052] According to some embodiments of the present invention, Figure 1-Figure 3 As shown, the two side walls of the first channel section 31 in the width direction are respectively the first wall 311 and the second wall 312, and the angle between the first wall 311 and the second wall 312 is α, which satisfies: 40°≤α≤60°. It can be understood that the angle between the first wall 311 and the second wall 312 satisfies: 40°≤α≤60°, which can ensure that the first channel section 31 has a good guiding and drainage effect while avoiding the injection molding material from being subjected to a large shear force. In some embodiments, when α is less than 40°, the injection molding material will be subjected to a large shear force when flowing through the first channel section 31, thereby causing the injection molding material to deteriorate (carbonize); when α is greater than 40°, the injection molding material is subjected to too small a shear force when flowing through the first channel section 31, resulting in a too fast drop in the injection molding material speed, affecting the injection molding efficiency. At the same time, when α is greater than 40°, the first channel section 31 has a low pre-mixing efficiency for the injection molding material, resulting in a poor mixing degree of the injection molding material entering the molding space.

[0053] According to some embodiments of the present invention, Figure 1-Figure 3As shown, the maximum width dimension of the first channel section 31 is w, which satisfies: 20mm≤w≤30mm. In some embodiments, the diameter of the injection port 12 is 10mm, and the width dimension of the end of the first channel section 31 away from the injection port 12 satisfies: 20mm≤w≤30mm. The injection material enters the first channel section 31 through the injection port 12, and enters the second channel section 32 and the third channel section 33 in turn after being guided by the first channel section 31. The width dimensions of the second channel section 32 and the third channel section 33 are both 20mm to 30mm.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0055] Although embodiments of the present invention have been shown and described above, changes, modifications, substitutions and variations may be made to the embodiments described above.

Claims

1. A mold assembly for injection molded parts, characterized in that: include: A first mold (10); a second mold (20), wherein the second mold (20) is connected to the first mold (10), and a molding space and an injection channel communicating with the molding space are formed between the first mold (10) and the second mold (20); A convex block (11), wherein the convex block (11) is arranged on the first mold (10) and / or the second mold (20), and the convex block (11) protrudes from the inner wall of the injection channel.

2. The mold assembly for injection molded parts according to claim 1, characterized in that: The injection channel comprises: A first channel section (31), the first channel section (31) extending in a horizontal direction, one end of the first channel section (31) being connected to the injection port (12), and the height of the first channel section (31) gradually decreasing in a direction away from the injection port (12); A second channel section (32), the second channel section (32) extends in a horizontal direction, one end of the second channel section (32) is connected to the other end of the first channel section (31), the other end of the second channel section (32) is connected to the molding space, and the protrusion (11) is arranged on the inner wall of the second channel section (32).

3. The mold assembly for injection molded parts according to claim 2, characterized in that: The convex block (11) is formed on the first mold (10), and the height of the convex block (11) gradually increases in a direction away from the first channel section (31).

4. The mold assembly for injection molded parts according to claim 3, characterized in that: The height of the second channel section (32) is h1, which satisfies: 1.5 mm ≤ h1 ≤ 1.8 mm; the maximum height of the protrusion (11) is h2, which satisfies: 0.4 mm ≤ h2 ≤ 0.6 mm.

5. The mold assembly for injection molded parts according to claim 4, characterized in that: The injection channel further comprises: a third channel section (33), the third channel section (33) being arranged between the second channel section (32) and the molding space and being suitable for connecting the second channel section (32) with the molding space, and the third channel section (33) extending in a height direction.

6. The mold assembly for injection molded parts according to claim 5, characterized in that: The height of the third channel section (33) is h3, which satisfies: 1.2 mm ≤ h3 ≤ 1.5 mm.

7. The mold assembly for injection molded parts according to claim 5, characterized in that: An arc-shaped transition section is formed on the second mold (20), and two ends of the arc-shaped transition section are respectively connected to the second channel section (32) and the third channel section (33).

8. The mold assembly for injection molded parts according to claim 2, characterized in that: In a direction away from the injection port (12), the width of the first channel section (31) gradually increases.

9. The mold assembly for injection molded parts according to claim 8, characterized in that: The two side walls of the first channel section (31) in the width direction are respectively a first wall (311) and a second wall (312); an included angle α between the first wall (311) and the second wall (312) satisfies: 40°≤α≤60°.

10. The mold assembly for injection molded parts according to claim 8, characterized in that: The maximum width dimension of the first channel section (31) is w, which satisfies: 20 mm ≤ w ≤ 30 mm.

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