Die for extruding B1-grade flame-retardant cable outer protective material

Abstract

The utility model discloses a mold for extruding a B1-grade flame-retardant cable outer protective material. The mold comprises a mold sleeve, and a mold sleeve core and a gland which are arranged along the axial direction, the die sleeve core is cylindrical, the contact position of the die sleeve core and the gland is provided with the step face, the gland is of an annular structure and arranged on the step face in a sleeving mode, the periphery of the gland is provided with the external threads used for being in threaded connection with the die sleeve, resources are saved, one original die needs to be machined according to one size, the die can share one die sleeve base, and only the die sleeve core needs to be replaced. And resources are greatly saved.

Description

Technical Field

[0001] The utility model belongs to the technical field of electric wire and cable production, and particularly relates to a die used for extruding B1-level flame-retardant cable outer sheath materials. Background Art

[0002] Cable outer sheath extrusion process: The outer sheath of B1-grade flame-retardant cable is extruded through a single-screw extruder. The B1-grade flame-retardant cable material loaded into the hopper enters the barrel with the help of gravity or feeding screw. Under the thrust of the rotating screw, it is continuously pushed forward, starting from the preheating section and gradually moving to the homogenization section; at the same time, the plastic is stirred and squeezed by the screw, and is transformed into a viscous flow state under the action of the external heat of the barrel and the shear friction between the plastic and the equipment, forming a continuous and uniform material flow in the screw groove. Under the action of the temperature specified by the process, the plastic is transformed from a solid state to a molten plastic object, and then the fully plasticized plastic is pushed into the machine head through the push or stirring of the screw; the material flow reaching the machine head is extruded from the mold sleeve mouth through the annular gap between the mold core and the mold sleeve, and is extruded on the cable core to form a continuous and dense sheath layer, and then cooled and solidified to make wire and cable products.

[0003] Currently, B1 grade materials are very hard and require high pressure during production, so they cannot be extruded by ordinary extruders. They can only be produced after customization by equipment manufacturers, and even then the production speed is very slow.

[0004] When the material passes through the die of the machine head, the die is all internally tapered, which creates pressure on the material, making the molecules of the material closer together. Friction will occur between the material and the die, causing increased resistance, making the material flow through the die at an uneven speed, resulting in uneven cable surface thickness.

[0005] In order to ensure that the material is extruded onto the cable surface with a more uniform thickness and to improve the mechanical properties of the B1 material, it is usually necessary to reduce the friction coefficient between the material and the die and reduce the amount of material remaining at the die outlet.

[0006] The utility model with announcement number CN219311968U discloses an extrusion die for an outer sheath of a cable, and the technical scheme thereof mainly includes an extrusion die core, an extrusion die sleeve and an extrusion flow channel, wherein the extrusion die core is threadedly assembled in the extrusion die sleeve to form the extrusion flow channel for extruding the outer sheath of the cable inside the two; wherein the extrusion die sleeve is radially provided with a color stripe injection port connected to the outer wall of the extrusion die core, the outer wall of the extrusion die core is circumferentially provided with an annular flow groove, and sub-injection ports connected to the extrusion flow channel are evenly provided along the annular flow groove, and the outer wall of the extrusion die core is also provided with an axially arranged connecting groove, and the connecting groove is used to connect the color stripe injection port and the annular flow groove; however, the extrusion die mainly has a color stripe injection port radially provided with the extrusion die sleeve, which is connected to the outer wall of the extrusion die core, and the original head injection port is used to inject material to the color stripe injection port on the outer wall of the extrusion die sleeve, so as to realize the synchronous extrusion of three identification strips, and cannot reduce the friction between the material and the die. Summary of the invention

[0007] The purpose of the utility model is to provide a mold for extruding B1 grade flame retardant cable outer sheath material in view of the deficiencies of the above-mentioned prior art, which adopts a mold sleeve core with a low friction coefficient, and when the mold size is changed, only the mold sleeve core needs to be replaced, thus saving resources.

[0008] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0009] A die for extruding B1-class flame-retardant cable sheath materials, comprising a die sleeve, a die sleeve core and a gland disposed axially at the end of the die sleeve;

[0010] The mold sleeve core is set to be cylindrical and the contact point between it and the pressure cover is set to be a step surface, while the pressure cover is set to be an annular structure and is sleeved on the step surface and its outer circumference is provided with external threads for threaded connection with the mold sleeve.

[0011] The core of the mold sleeve is provided with an extrusion channel, and the end of the extrusion channel is provided with a mounting hole for mounting the mold sleeve core, and the outer diameter of the mounting hole is greater than the inner diameter of the end of the extrusion channel.

[0012] The gland is also provided with a disassembly hole for disassembly.

[0013] The mold sleeve core is made of polytetrafluoroethylene with a low friction coefficient.

[0014] The axial length of the mold sleeve core is set to 3-5 mm.

[0015] The extrusion channel is configured as a hammer-shaped channel with a gradually decreasing inner diameter and smoothly transitions to the inner hole of the die sleeve core.

[0016] The beneficial effects of the utility model are:

[0017] (1) The die for extruding B1-class flame-retardant cable sheath material comprises a die sleeve and a die sleeve core and a gland arranged along the axial direction; the die sleeve core is set to be cylindrical and the contact point between it and the gland is set to be a step surface, while the gland is set to be an annular structure and sleeved on the step surface and its outer circumference is provided with an external thread for threaded connection with the die sleeve, thereby saving resources. The original die needs to be processed one by one size, while the die can share a die sleeve base, and only the die sleeve core needs to be replaced, thereby greatly saving resources.

[0018] (2) The replacement efficiency is improved. When replacing, only the mold sleeve core needs to be replaced, and the mold sleeve base does not need to be disassembled.

[0019] (3) The surface quality of the product is improved. The mold core is made of polymer material, which reduces the friction between the material and the mold, makes the material smoother, and thus increases the physical and mechanical properties of the material.

[0020] (4) Reduce the length of the material receiving area of ​​the die sleeve core, thereby reducing the residence time of the material in the die sleeve receiving area, better matching the extrusion of B1 grade high hardness materials, with a rounded surface and consistent thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the utility model;

[0022] Figure 2 It is a structural diagram of the mold sleeve. DETAILED DESCRIPTION

[0023] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0024] The present invention provides a die and an extrusion method for extruding a B1-class flame-retardant cable outer sheath material, such as Figure 1 and Figure 2 shown.

[0025] A die for extruding B1-class flame-retardant cable sheath material, comprising a die sleeve 1, a die sleeve core 2 and a gland 3 axially arranged at the end of the die sleeve 1, and the die sleeve core 2 is made of a material with a low friction coefficient; the die sleeve core 2 is set to be cylindrical and the contact point between it and the gland 3 is set to be a step surface, and the gland 3 is set to be an annular structure and sleeved on the step surface and its outer circumference is provided with an external thread for threaded connection with the die sleeve 1. The die sleeve 1 is provided with an extrusion channel 11 in the center and a mounting hole 12 for mounting the die sleeve core is provided at the end of the extrusion channel, and the outer diameter of the mounting hole 12 is larger than the inner diameter of the end of the extrusion channel 11.

[0026] The gland 3 is also provided with a disassembly hole 31 for disassembly. In this embodiment, the die core 2 is made of polytetrafluoroethylene, a material with a low friction coefficient, and the axial length of the die core is set to 3-5 mm, which reduces the friction between the material and the die, is more lubricated, and the surface of the extruded material is smoother, and the physical and mechanical properties of the material test are better. In addition, a gland 3 is added outside the die core 2 to fix the die core 2, and an 8mm screw disassembly hole is punched on the gland for easy disassembly.

[0027] The extrusion channel 11 is configured as a hammer-shaped channel with a gradually decreasing inner diameter and smoothly transitions with the inner hole of the mold sleeve core 2. When the extruder is in normal use and a mold sleeve of similar size needs to be replaced, only the mold sleeve core needs to be replaced without disassembling the entire mold sleeve, thereby improving replacement efficiency. At the same time, during processing, only the mold sleeve core needs to be processed, thereby reducing the cost of using the mold.

[0028] The extrusion method of the die for extruding B1-class flame-retardant cable sheath material comprises the following steps:

[0029] (1) Select the extrusion process according to the production, and select the finished plate and raw materials according to the extrusion process;

[0030] (2) Mold matching: Select appropriate tooling mold according to the outer diameter of the cable and assemble it;

[0031] (3) Prepare semi-finished products and finished products;

[0032] (4) Adjust the eccentricity of the extruded material and the content to be printed;

[0033] (5) In extrusion production, measure the outer diameter and control the thickness.

[0034] In step (2), when matching the mold, the stretching balance ratio is 1.2~1.3, so that the distance from the material extruded to the cable core is shortened, close to the cable core, and the inner diameter of the mold core is 7~10mm larger than the outer diameter of the cable. At the same time, in order to further ensure the flame retardant performance and ensure that the extruded material is as close to the cable core as possible, a vacuum device can be added at the inlet position to generate negative pressure so that the material is close to the cable core.

[0035] The inner side of the die sleeve rubs against the extruded material for a long time, resulting in greater resistance. In order to reduce the pressure inside the die sleeve as much as possible, the inner surface is made as smooth as possible during processing.

[0036] The processing technology of each component in the present invention is described below:

[0037] Mold sets

[0038] The steel material is processed and then nitrided. The nitriding mold is the core of the processing. In this step, the mold is placed in a nitriding furnace containing nitrogen gas, and then high temperature, high pressure and other conditions are used to allow nitrogen atoms to penetrate into the surface of the metal material to form a nitrided layer. The nitriding depth can reach 0.4-0.5mm, which can significantly improve the hardness and wear resistance of the mold and extend its service life. After nitriding, the surface has a frosted feel and needs to be polished. Polishing requires multiple grinding and polishing. Polishing sandpaper with different roughness is used for step-by-step grinding. The workpiece surface is processed using flexible polishing tools and abrasives or other polishing media, and the rough texture is first ground off with an oil stone, and then polished with fine sandpaper. Finally, polishing is performed with polishing paste or grinding paste to achieve the required polishing effect, and the surface finish can reach up to level 10.

[0039] Mold core:

[0040] The mold core is made of polytetrafluoroethylene material, which has a relatively low friction coefficient compared to most solid materials, good self-cleaning properties, is not affected by ultraviolet rays, is fatigue-resistant, distortion-resistant, aging-resistant, has a long service life, and has outstanding corrosion resistance. Therefore, after contacting with B1 flame-retardant material, the friction is small and the material flow is smooth.

[0041] Mold core gland:

[0042] Since this component is a vulnerable part, this embodiment uses ordinary 45# steel, which has a lower hardness than the mold sleeve and protects the mold sleeve.

[0043] Disassembly and assembly of mold core:

[0044] A tooling for disassembling the mold sleeve core gland is specially designed. The tooling is fixed to the two holes on the mold sleeve core gland by rotating it to unscrew the gland and remove the mold sleeve core for replacement.

[0045] The die and extrusion method for extruding B1-class flame-retardant cable outer sheath material save resources through the die sleeve and the die sleeve core and the pressure cover arranged along the axial direction. The original die needs to be processed one by one size, while the die can share a die sleeve base, and only the die sleeve core needs to be replaced, which greatly saves resources; at the same time, the replacement efficiency is improved, and when replacing, only the die sleeve core needs to be replaced, and the die sleeve base does not need to be disassembled; the surface quality of the product is improved, the die sleeve core adopts a polymer material, the friction between the material and the die is reduced, and the material is smoother, thereby increasing the physical and mechanical properties of the material; the length of the material receiving area of ​​the die sleeve core is reduced, and the residence time of the material in the die sleeve wire receiving area is reduced, so as to better match the extrusion of B1-class high-hardness materials, and the surface is round and the thickness is consistent.

[0046] If the words "first", "second" and the like are used in this patent to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of describing the present invention and simplifying the description, and the above words have no special meaning.

[0047] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the invention claimed for protection. The scope of protection claimed for the present invention is defined by the attached claims and their equivalents.

[0048] In the description of the present invention, it is necessary to understand that the terms "front", "rear", "left", "right", "center", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the protection content of the present invention.

Claims

1. A die for extrusion of B1 grade flame retardant cable sheath material, characterized by: It includes a mold sleeve, a mold sleeve core and a pressure cover which are axially arranged at the end of the mold sleeve, and the mold sleeve core is made of a material with a low friction coefficient; The die sleeve core is set to be cylindrical and the contact point between it and the gland is set to be a step surface, while the gland is set to be an annular structure and sleeved on the step surface and its outer circumference is provided with external threads for threaded connection with the die sleeve; The axial length of the mold sleeve core is set to 3-5 mm.

2. The die for extruding B1-class flame-retardant cable sheath material according to claim 1, characterized in that: The core of the mold sleeve is provided with an extrusion channel, and the end of the extrusion channel is provided with a mounting hole for mounting the mold sleeve core, and the outer diameter of the mounting hole is greater than the inner diameter of the end of the extrusion channel.

3. The die for extruding B1-class flame-retardant cable sheath material according to claim 2, characterized in that: The extrusion channel is configured as a hammer-shaped channel with a gradually decreasing inner diameter and smoothly transitions to the inner hole of the die sleeve core.

4. The die for extruding B1-class flame-retardant cable sheath material according to claim 1, characterized in that: The gland is also provided with a disassembly hole for disassembly.

5. A die for extruding B1-class flame-retardant cable sheath material according to any one of claims 1 to 4, characterized in that: The mold sleeve core is made of polytetrafluoroethylene with a low friction coefficient.

6. The die for extruding B1-class flame-retardant cable sheath material according to claim 5, characterized in that: The gland is made of 45# steel.

7. The die for extruding B1-class flame-retardant cable sheath material according to claim 5, characterized in that: The die sleeve is made of steel and is nitrided.

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