A die for cable extrusion

Abstract

The utility model relates to cable manufacturing technical field, concretely relates to a die bushing for cable extrusion, including die bushing main part, die bushing main part has die bushing import, die bushing export and runner, along the length direction of die bushing main part, die bushing import and die bushing export are separately arranged at both ends of die bushing main part, the runner is trunconical and has feeding hole and discharge hole, the cross section size of feeding hole is greater than the cross section size of discharge hole, feeding hole constitutes die bushing import, discharge hole constitutes die bushing export, wherein, the end surface of die bushing main part near die bushing import is plane, the end surface of die bushing main part near die bushing export is concave and forms recess inward, in the length direction of die bushing main part, the projection of recess is circular ring shape, this application can improve the qualified rate of cable, promote production efficiency and reduce the cost of loss.

Description

Technical Field

[0001] This utility model relates to the field of cable manufacturing technology, and specifically to a die for cable extrusion. Background Technology

[0002] In recent years, security standards have been continuously improving. During a fire, the combustion of halogenated materials produces large amounts of toxic halogenated fumes, causing suffocation or obstructed vision, hindering rescue and escape. Therefore, low-smoke halogen-free cables have emerged. To improve the flame-retardant properties of low-smoke halogen-free materials such as TPU, halogenated flame retardants are used. However, the halogens in these flame retardants violate security regulations in some regions, affecting the application scope of these cables. To address this issue, low-smoke halogen-free flame-retardant materials typically use inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide. However, because the flame-retardant efficacy of inorganic flame retardants is far lower than that of halogenated flame retardants, the amount required is much greater than that of halogenated flame retardants. To ensure the fusion of inorganic particles with the substrate, a coupling agent, such as silicone masterbatch or silane coupling agent, needs to be added along with the inorganic flame retardant for the fusion of inorganic particles and organic materials.

[0003] During cable extrusion, the screw rotation pushes the plastic forward while the barrel remains stationary. Relative motion occurs between the barrel and screw, and the friction between the barrel's inner wall and the low-smoke halogen-free material is greater than the friction between the screw surface and the material. The material is "draggled" along the screw grooves towards the die head, while the conveying action of the grooves further propels the material. Simultaneously, the resistance from the die, perforated screen, and filter in the die head, as well as the matching degree between the screw compression section and the material properties, collectively generate a reaction force as the low-smoke halogen-free material advances, resulting in backflow and leakage. Since low-smoke halogen-free materials have a low melt index and high extrusion viscosity, the material experiences both "dragging flow" and "pressure flow" simultaneously within the screw grooves. This superposition creates a strong shear field, generating significant shear stress, which intensifies friction between the material and the screw, die head, and mold. This shear stress is converted into frictional heat, generating a large amount of additional heat.

[0004] During extrusion production, some materials decompose due to excessive heating. For example, silicone masterbatch (which functions as both a lubricant and a coupling agent) can effectively improve the compatibility of inorganic fillers and resins, but its disadvantage is its low thermal decomposition temperature. The large amount of heat generated during extrusion can easily cause silicone masterbatch and other additives to decompose and become ineffective. The separated decomposition products are poorly dispersed in the melt material system, thus causing friction and adsorption with metal surfaces such as the screw and die.

[0005] In the extrusion process, taking coupling agents as an example (flame retardants, fillers, and other materials may also decompose), impurities generated from the decomposition of coupling agents gradually adhere to the surface of the extruded melt stream. When the melt stream flows to the die head (especially at the die opening), the impurities gradually separate from the melt and float on the surface of the melt stream. After the melt stream leaves the die, it begins to cool and crystallize under rapid heating conditions, and impurities easily adhere to the die surface, forming die-hole accumulation. In particular, existing sizing zones are located near the die exit. These sizing zones are generally cylindrical and have a smaller cross-sectional size than other areas inside the die, causing impurities to be subjected to greater pressure as they leave the die exit, resulting in adhesion near the die exit. Die-hole accumulation can easily lead to uneven cable outer diameter. For example, if die-hole accumulation reaches a certain level, impurities will form lumps and deposit on the cable surface with the melt stream, requiring cable segmentation, increasing the cable defect rate, and causing some cables to be scrapped.

[0006] Therefore, how to overcome the shortcomings of the existing technology mentioned above has become the subject of this utility model. Utility Model Content

[0007] The purpose of this invention is to provide a die for cable extrusion.

[0008] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0009] A die for cable extrusion includes a die body having a die inlet, a die outlet, and a flow channel;

[0010] Along the length of the mold body, the mold inlet and the mold outlet are respectively located at both ends of the mold body;

[0011] The flow channel is frustum-shaped and has an inlet and an outlet; the cross-sectional dimension of the inlet is larger than that of the outlet; the inlet constitutes the mold sleeve inlet, and the outlet constitutes the mold sleeve outlet;

[0012] Wherein, the end surface of the mold body near the mold inlet is flat; the end surface of the mold body near the mold outlet is recessed inward to form a concave portion; and the projection of the concave portion along the length direction of the mold body is annular.

[0013] Based on existing understanding, the main body of the mold is actually an improvement on the existing mold with some details, and the operating principle is basically the same as the existing mold.

[0014] The flow channel is frustum-shaped and has an inlet and an outlet. The cross-sectional dimension of the inlet is larger than that of the outlet. The inlet forms the mold sleeve inlet, and the outlet forms the mold sleeve outlet. Based on this, the sizing zone near the mold sleeve outlet on the existing mold sleeve is eliminated (at this time, there is no square or approximately square area in the flow channel), so that impurities will not be subjected to greater pressure and adhere to the vicinity of the mold sleeve outlet when leaving the mold sleeve body. On this basis, by setting a recess, these impurities or small particles formed by the aggregation of impurities (described below as small particle impurities) can enter the recess, and may gradually form viscous slurry (small particle impurities can continue to be heated after entering the recess). The operator only needs to use tweezers to grasp the viscous slurry and then remove it (for example).

[0015] In summary, after the sizing zone is eliminated, small particulate impurities are less likely to adhere to the vicinity of the die outlet and are less likely to form blocky impurities (which may also be elongated, etc., but will be described as blocky impurities). Furthermore, due to the recess, these small particulate impurities are more likely to enter the recess and form viscous slurry after subsequent heating. This suppresses the phenomenon that these small particulate impurities gradually form blocky impurities and adhere to the cable surface with the molten material flow, thereby improving the cable qualification rate and reducing loss costs.

[0016] For comparison, the following explanation is provided: During die extrusion, impurities produced by the decomposition of inorganic substances in the material crystallize and accumulate, forming powdery impurities. These impurities accumulate and adhere to the die surface as the molten material is extruded. After accumulating to a certain extent, they suddenly "break" and flow to the cable surface with the molten material, resulting in a rough cable surface with granular or continuous striped bumps. This forces the continuous production of cables to be segmented. The improved die in this application solves this problem.

[0017] It should be noted that this application only adjusts the details of the mold structure and does not change the way the mold is used. The way it is used to produce cables is the same as the existing method.

[0018] In a further technical solution, the recess includes a first wall portion and a second wall portion that are in contact with each other;

[0019] Along the length of the mold body, the projections of the first wall portion and the second wall portion are both annular.

[0020] The first wall portion is connected to the edge of the mold sleeve outlet;

[0021] The second wall portion is in contact with the edge of the end surface of the mold body near the mold outlet.

[0022] In this section, the recessed area has a large capacity, ensuring sufficient storage for impurities. Based on the annular projection, the first and second walls can be inclined planes or curved surfaces, facilitating the flow of impurities within the recess.

[0023] In a further technical solution, the first wall portion is connected to the edge of the mold sleeve outlet via a first plane;

[0024] And / or, the second wall portion is connected to the edge of the end surface of the mold body near the mold outlet via a second plane.

[0025] The following explanation uses the "enclosing structure that forms an approximately frustum-shaped structure by the self-enclosing of the first wall portion" as an example: The setting of the first plane ensures that the end of the enclosing structure near the mold outlet (i.e., the "small end" below) has a certain thickness, thereby ensuring the structural strength of the mold body near the mold outlet and preventing this end from being easily damaged. The effect of setting the second plane is the same as that explained for the first plane.

[0026] A further technical solution is that the first wall portion is a single curved surface, and the curved surface bends toward the mold outlet, which facilitates the flow of fluid in the recess and makes the inner space of the recess larger.

[0027] The first wall portion encloses itself to form an enclosed structure that approximates a frustum shape. The difference is that the outer surface of the sidewall of the frustum shape can be considered a plane (also an inclined plane), while the outer surface of the sidewall of the enclosed structure is a single curved surface (similar to the surface of a semicircle, not a combination of multiple curved surfaces). The enclosed structure has a large end and a small end, with the small end closer to the mold outlet.

[0028] In a further technical solution, the second wall portion is a single curved surface, and this curved surface bends towards the mold outlet. This arrangement further facilitates fluid flow within the recess and also increases the inner space of the recess.

[0029] In a further technical solution, both the mold body and the flow channel are axisymmetric structures with a first axis as the axis of symmetry, and the first axis extends along the length direction of the mold body.

[0030] The main body of the mold is an axisymmetric structure, which can not only ensure structural strength, but also facilitate the flow channel to be an axisymmetric structure.

[0031] The flow channel has an axisymmetric structure, which allows the melt to be subjected to uniform force within the flow channel, ensuring product quality.

[0032] A further technical solution is that the recess is an axisymmetric structure with the first axis as the axis of symmetry. Based on this configuration, the structural strength of the corresponding end of the mold body can be guaranteed, and it is also beneficial to ensure that impurities flowing out of the flow channel flow in several directions to enter the recess.

[0033] In a further technical solution, any area of ​​the end surface of the mold body near the mold outlet and any area of ​​the surface of the recess are covered with a polytetrafluoroethylene coating.

[0034] Preferably, a PTFE coating with a thickness of 55-70 μm can be applied to the corresponding end surface of the mold body using a PTFE coating process (such as deposition). This coating can reduce the adhesion of (small particulate) impurities to the corresponding surface (such as the first plane), ensuring that impurities can be deposited into the recess and preventing them from adhering to the cable surface with the molten material flow. The deposition of impurities into the recess also prevents them from easily adhering.

[0035] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0036] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0037] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0038] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the case.

[0039] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0040] The working principle and advantages of this utility model are as follows:

[0041] The flow channel is frustum-shaped and has an inlet and an outlet. The cross-sectional dimension of the inlet is larger than that of the outlet. The inlet forms the mold sleeve inlet, and the outlet forms the mold sleeve outlet. Based on this, the sizing zone near the mold sleeve outlet on the existing mold sleeve is eliminated, so that impurities will not be subjected to greater pressure and adhere to the vicinity of the mold sleeve outlet when leaving the mold sleeve body. On this basis, by setting a recess, these impurities or small particles formed by the aggregation of impurities (described below as small particle impurities) can enter the recess, and then gradually form a viscous slurry (the small particle impurities can continue to be heated after entering the recess). The operator only needs to use tweezers to grasp the viscous slurry and then remove it (for example).

[0042] In summary, after the sizing zone is eliminated, small particulate impurities are less likely to adhere to the vicinity of the die outlet and are less likely to form blocky impurities (which may also be elongated, etc., but will be described as blocky impurities). Furthermore, due to the recess, these small particulate impurities are more likely to enter the recess and form viscous slurry after subsequent heating. This suppresses the phenomenon that these small particulate impurities gradually form blocky impurities and adhere to the cable surface with the molten material flow, thereby improving the cable qualification rate and reducing loss costs. Attached Figure Description

[0043] Figure 1 This is a front view of the extrusion die sleeve according to an embodiment of the present utility model;

[0044] Figure 2 This is a cross-sectional view of the extrusion die sleeve according to an embodiment of the present invention.

[0045] In the above figures: 1. Mold body; 11. Mold inlet; 12. Mold outlet; 13. Flow channel; 131. Feed hole; 132. Discharge hole; 2. Recess; 21. First wall; 22. Second wall; 3. First plane; 4. Second plane; 5. First axis. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0047] Example: The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the examples of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0048] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0049] See Figures 1-2A die for cable extrusion includes a die body 1, the die body 1 having a die inlet 11, a die outlet 12 and a flow channel 13;

[0050] Along the length of the mold body 1, the mold inlet 11 and the mold outlet 12 are respectively located at both ends of the mold body 1;

[0051] The flow channel 13 is frustum-shaped and has an inlet hole 131 and an outlet hole 132; the cross-sectional dimension of the inlet hole 131 is larger than the cross-sectional dimension of the outlet hole 132; the inlet hole 131 constitutes the mold sleeve inlet 11, and the outlet hole 132 constitutes the mold sleeve outlet 12.

[0052] Wherein, the end surface of the mold body 1 near the mold inlet 11 is flat; the end surface of the mold body 1 near the mold outlet 12 is recessed inward to form a recess 2; in the length direction of the mold body 1, the projection of the recess 2 is annular.

[0053] The main body 1 of the mold sleeve, based on existing understanding, is actually a detailed improvement on the existing mold sleeve, and its operating principle is basically the same as the existing mold sleeve. The shape of the cable and the main body 1 is understood based on existing understanding, and is considered cylindrical to ignore production factors, and is described accordingly.

[0054] The flow channel 13 is frustum-shaped and has an inlet 131 and an outlet 132. The cross-sectional dimension of the inlet 131 is larger than that of the outlet 132. The inlet 131 constitutes the mold sleeve inlet 11, and the outlet 132 constitutes the mold sleeve outlet 12. Based on this, the sizing area near the mold sleeve outlet 12 on the existing mold sleeve is eliminated (at this time, the flow channel 13 does not have a square or approximately square cross-section area, which can also be described as a cylindrical area), so that impurities will not be subjected to greater pressure and adhere to the vicinity of the mold sleeve outlet 12 when leaving the mold sleeve body 1 through the mold sleeve outlet 12. On this basis, by setting the recess 2, these impurities or small particles formed by the aggregation of impurities (described below as small particle impurities) can enter the recess 2, and may gradually form viscous slurry (small particle impurities can continue to be heated after entering the recess 2). The operator only needs to use tweezers to grasp the viscous slurry and remove it (for example).

[0055] In summary, after the sizing zone is eliminated, small particulate impurities are less likely to adhere to the vicinity of the die sleeve outlet 12 and are less likely to form blocky impurities (which may also be elongated, etc., but will be described as blocky impurities). Furthermore, due to the setting of the recess 2, these small particulate impurities are more likely to enter the recess 2 and form viscous slurry after subsequent heating. This suppresses the phenomenon that these small particulate impurities gradually form blocky impurities and adhere to the cable surface with the melt flow, thereby improving the cable qualification rate and reducing loss costs.

[0056] For comparison, the following explanation is provided: During die extrusion, impurities produced by the decomposition of inorganic substances in the material crystallize and accumulate, forming powdery impurities. These impurities accumulate and adhere to the die surface as the molten material is extruded. After accumulating to a certain extent, they suddenly "break" and then flow to the cable surface with the molten material, resulting in a rough cable surface with granular or continuous striped bumps. This forces the cable, which should be produced continuously, to be segmented. The improved die in this embodiment solves this problem.

[0057] It should be noted that this embodiment only adjusts the details of the mold structure and does not change the way the mold is used. The way it is used to produce cables is the same as the existing method.

[0058] In this embodiment, the recess 2 includes a first wall portion 21 and a second wall portion 22 that are in contact with each other;

[0059] Along the length of the mold body 1, the projections of the first wall portion 21 and the second wall portion 22 are both annular.

[0060] The first wall portion 21 is in contact with the edge of the mold sleeve outlet 12;

[0061] The second wall portion 22 is in contact with the edge of the end surface of the mold body 1 near the mold outlet 12.

[0062] In this section, the recess 2 has a large capacity, ensuring sufficient storage for impurities. Based on the annular projection, the first wall 21 and the second wall 22 can be inclined planes or curved surfaces, facilitating the flow of impurities within the recess 2.

[0063] In this embodiment, the first wall portion 21 is connected to the edge of the mold outlet 12 via the first plane 3;

[0064] And / or, the second wall portion 22 is connected to the edge of the end surface of the mold body 1 near the mold outlet 12 via the second plane 4.

[0065] The following description, "the enclosing structure formed by the first wall portion 21 itself into an approximately frustum-shaped structure," illustrates this: the first plane 3 ensures that the end of the enclosing structure near the mold outlet 12 (i.e., the "small end") has a certain thickness, thereby guaranteeing the structural strength of the end of the mold body 1 near the mold outlet 12 and preventing that end from being easily damaged. The effect of the second plane 4 is the same as that described for the first plane 3.

[0066] In this embodiment, the first wall portion 21 is a single curved surface, and the curved surface bends toward the mold outlet 12, which facilitates the flow of fluid in the recess 2 and makes the inner space of the recess 2 larger.

[0067] The first wall portion 21 encloses itself to form an enclosed structure that approximates a frustum shape. The difference is that the outer surface of the side wall of the frustum shape can be considered as a plane (also an inclined plane), while the outer surface of the side wall of the enclosed structure is a single curved surface (refer to the surface of a semicircle, not a combination of multiple curved surfaces). The enclosed structure has a large end and a small end, with the small end close to the mold outlet 12.

[0068] In this embodiment, the second wall portion 22 is a single curved surface, and this curved surface bends toward the mold outlet 12. This arrangement further facilitates fluid flow within the recess 2, while also increasing the inner space of the recess 2.

[0069] In this embodiment, both the mold body 1 and the flow channel 13 are axisymmetric structures with the first axis 5 as the axis of symmetry, and the first axis 5 extends along the length direction of the mold body 1.

[0070] The main body of the mold sleeve 1 is an axisymmetric structure, which not only ensures structural strength but also facilitates the axisymmetric structure of the flow channel 13. The main body of the mold sleeve 1 can be regarded as a cylindrical structure, and the flow channel 13 can be regarded as a frustum-shaped structure.

[0071] The flow channel 13 has an axisymmetric structure, which can make the melt be subjected to uniform force within the flow channel 13, thus ensuring product quality.

[0072] In this embodiment, the recess 2 is an axisymmetric structure with the first axis 5 as the axis of symmetry. Based on this setting, the structural strength of the corresponding end of the mold body 1 can be guaranteed, and it is also beneficial to ensure that impurities flowing out of the flow channel 13 flow in several directions to flow into the recess 2.

[0073] In this embodiment, any area of ​​the end surface of the mold body 1 near the mold outlet 12 and any area of ​​the surface of the recess 2 are covered with a polytetrafluoroethylene coating.

[0074] Preferably, a PTFE coating with a thickness of 55-70 μm (not shown in the figure) can be applied to the corresponding end surface of the mold body 1 using a PTFE coating process (such as deposition). This coating can reduce the adhesion of (small particulate) impurities to the corresponding surface (such as the first plane 3), ensuring that impurities can be deposited into the recess 2 and preventing impurities from adhering to the cable surface with the molten material flow. After the impurities are deposited into the recess 2, they are also prevented from easily adhering.

[0075] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. A die for cable extrusion, characterized in that: It includes a mold body (1), which has a mold inlet (11), a mold outlet (12) and a flow channel (13). Along the length of the mold body (1), the mold inlet (11) and the mold outlet (12) are respectively located at both ends of the mold body (1); The flow channel (13) is frustum-shaped and has an inlet hole (131) and an outlet hole (132); the cross-sectional dimension of the inlet hole (131) is larger than the cross-sectional dimension of the outlet hole (132); the inlet hole (131) constitutes the mold inlet (11), and the outlet hole (132) constitutes the mold outlet (12). Wherein, the end surface of the mold body (1) near the mold inlet (11) is flat; the end surface of the mold body (1) near the mold outlet (12) is recessed inward to form a recess (2); in the length direction of the mold body (1), the projection of the recess (2) is annular.

2. The die sleeve for cable extrusion according to claim 1, characterized in that: The recess (2) includes a first wall portion (21) and a second wall portion (22) that are in contact with each other. Along the length of the mold body (1), the projections of the first wall portion (21) and the second wall portion (22) are both annular; The first wall portion (21) is in contact with the edge of the mold sleeve outlet (12); The second wall portion (22) is in contact with the edge of the end surface of the mold body (1) near the mold outlet (12).

3. A die for cable extrusion according to claim 2, characterized in that: The first wall portion (21) is connected to the edge of the mold outlet (12) through the first plane (3); And / or, the second wall portion (22) is connected to the edge of the end surface of the mold body (1) near the mold outlet (12) via the second plane (4).

4. A die for cable extrusion according to claim 2, characterized in that: The first wall portion (21) is a single curved surface, and the curved surface is bent toward the mold outlet (12).

5. A die for cable extrusion according to claim 4, characterized in that: The second wall portion (22) is a single curved surface, and the curved surface bends toward the mold outlet (12).

6. A die for cable extrusion according to any one of claims 1-5, characterized in that: Both the mold body (1) and the flow channel (13) are axisymmetric structures with the first axis (5) as the axis of symmetry, and the first axis (5) extends along the length direction of the mold body (1).

7. A die for cable extrusion according to claim 6, characterized in that: The recess (2) is an axisymmetric structure with the first axis (5) as the axis of symmetry.

8. A die for cable extrusion according to any one of claims 1-5, characterized in that: Any area of ​​the end surface of the main body of the mold (1) near the mold outlet (12) and any area of ​​the surface of the recess (2) are covered with a polytetrafluoroethylene coating.

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