Uniform temperature die structure of low-smoke halogen-free cable extruder

Abstract

The utility model discloses a kind of temperature equalizing die head structures of low smoke halogen-free cable extruder, belong to extruder die head technical field, the temperature equalizing die head structure structure of this low smoke halogen-free cable extruder includes die head body, die core and die sleeve set in die head body, melt inlet is equipped on die head body;Spiral flow sleeve is sleeved outside die core, and outer layer spiral flow passage for passing through polymer melt is formed between spiral flow sleeve and the inner wall of die head body;Spiral flow sleeve inside is equipped with independent closed fluid passage, circulating heat-conducting fluid is passed into in fluid passage, for heating and temperature regulation to die head. The temperature equalizing die head structure of this low smoke halogen-free cable extruder is physically homogenized by polymer melt in spiral flow passage, simultaneously, the composite temperature control system consisting of circulating heat-conducting oil and external electric heating, accurate, uniform heat management from inside to outside to melt flow channel, ensure that melt is always in optimum processing temperature window.

Description

Technical Field

[0001] This utility model relates to the field of extruder die head technology, specifically a uniform temperature die head structure for a low-smoke halogen-free cable extruder. Background Technology

[0002] Cables, as carriers of electrical energy and information transmission, are widely used in various fields such as construction, transportation, and energy. In recent years, with the increasing awareness of safety, extremely high requirements have been placed on the flame-retardant properties of cables in densely populated places (such as subways, airports, and high-rise buildings). Low-smoke halogen-free cables have become the preferred choice for these scenarios because they do not release halogen-containing toxic gases and produce low smoke during combustion. The insulation and sheathing materials of low-smoke halogen-free cables are mainly composed of polyolefins (such as polyethylene and EVA) filled with a large amount of metal hydrates (such as aluminum hydroxide and magnesium hydroxide). These fillers give the cables excellent flame-retardant properties, but also lead to inherent processing difficulties: high melt viscosity, significant shear heat generation effect, and extremely high thermal sensitivity.

[0003] The extrusion die is a key component in cable extrusion molding, its core function being to uniformly and stably coat the molten material from the extruder onto the conductor or cable core. Currently, the cable extrusion dies commonly used in the industry mainly fall into two structural forms: 1. Ordinary straight-through dies with external heating coils, which suffer from poor temperature uniformity, low temperature control accuracy, slow response, and are prone to forming dead zones and material accumulation in the flow channel; 2. Spiral dies, which typically still use external electric heating coils for temperature control, and the aforementioned problems of poor temperature uniformity and slow response persist. Neither of these solutions can meet the stringent requirements of low-smoke halogen-free materials.

[0004] Therefore, the temperature control systems of existing die head structures, whether simple straight-through or improved spiral types, are all based on an outside-to-inside heating mode, making it impossible to achieve active, uniform, and precise temperature management of the core area inside the die head. This has become a technical bottleneck restricting the improvement of production efficiency and product quality of high-quality low-smoke halogen-free cables. Utility Model Content

[0005] This utility model provides a uniform temperature die head structure for a low-smoke halogen-free cable extruder, aiming to solve the problems mentioned in the background art, such as the inability of existing die head structures to achieve active, uniform, and precise temperature management of the core area inside the die head.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a uniform temperature die structure for a low-smoke halogen-free cable extruder, comprising a die body, a die core and a die sleeve disposed within the die body, wherein the die body is provided with a melt inlet; a spiral flow divider sleeve is sleeved on the outer side of the die core, and an outer spiral flow channel for passing polymer melt is formed between the spiral flow divider sleeve and the inner wall of the die body; an independent closed fluid channel is provided inside the spiral flow divider sleeve, and a circulating heat-conducting fluid is introduced into the fluid channel for heating and temperature regulation of the die.

[0007] Preferably, the fluid channel is a spiral channel arranged around the axis of the mold core.

[0008] Preferably, the spiral flow divider sleeve is provided with a heat-conducting fluid inlet and a heat-conducting fluid outlet communicating with the fluid channel. The heat-conducting fluid inlet and the heat-conducting fluid outlet extend to the outside of the mold head body for connecting to an external temperature control device.

[0009] Preferably, the fluid channel, the heat-conducting fluid inlet, and the heat-conducting fluid outlet constitute an independent temperature control unit; at least two temperature control units are arranged along the mold head axis to achieve independent temperature control of different areas of the mold head.

[0010] Preferably, a cylindrical electric heating coil is provided on the outside of the mold head body.

[0011] Preferably, the circulating heat transfer fluid is heat transfer oil.

[0012] The uniform temperature die head structure of this low-smoke halogen-free cable extruder is simple and easy to use, and has the following advantages:

[0013] 1. This utility model achieves precise and uniform thermal management of the melt flow channel from the inside to the outside by setting an internal spiral flow channel for heat transfer oil circulation, ensuring that the melt is always within the optimal processing temperature window.

[0014] 2. This utility model completely eliminates the porosity and pitting caused by local overheating, as well as the "bambooing" phenomenon caused by pressure fluctuations, through a uniform temperature field and stable extrusion pressure, making the cable surface extremely smooth and dense, and significantly improving product quality.

[0015] 3. By setting up a heat-conducting fluid circulation, this utility model has a large heat capacity and high heat transfer efficiency of the heat-conducting oil, which greatly shortens the time required for the mold head to heat up and the process to stabilize. It effectively prevents frequent shutdowns for mold cleaning caused by defects such as carbon buildup, crystal points, and glue breakage, extends continuous production time, and improves the overall efficiency of the equipment. Attached Figure Description

[0016] Figure 1A schematic diagram of the front structure of the isothermal die head structure of a low-smoke halogen-free cable extruder;

[0017] Figure 2 This is a schematic diagram of the internal structure of the die body in the isothermal die structure of a low-smoke halogen-free cable extruder.

[0018] Figure 3 This is a schematic diagram of the cross-sectional structure of the die body in the uniform temperature die structure of a low-smoke halogen-free cable extruder.

[0019] Figure 4 This is a schematic cross-sectional view of the tail section of the outer spiral flow channel in the isothermal die structure of a low-smoke halogen-free cable extruder.

[0020] In the picture:

[0021] 1. Die head body; 11. Melt inlet;

[0022] 2. Mold core;

[0023] 3. Mold;

[0024] 4. Spiral flow divider sleeve; 41. Outer spiral flow channel; 42. Fluid channel; 43. Heat transfer fluid inlet; 44. Heat transfer fluid outlet;

[0025] 5. Cylindrical electric heating coil;

[0026] 6. External temperature control equipment. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] This embodiment provides a uniform temperature die structure for a low-smoke halogen-free cable extruder, such as... Figures 1 to 4 As shown, the uniform temperature die structure of the low-smoke halogen-free cable extruder includes a die body 1, a die core 2 and a die sleeve 3 disposed inside the die body 1. The die body 1 is provided with a melt inlet 11. A spiral flow divider 4 is sleeved on the outside of the die core 2. An outer spiral flow channel 41 for passing polymer melt is formed between the spiral flow divider 4 and the inner wall of the die body 1. An independent closed fluid channel 42 is provided inside the spiral flow divider 4. A circulating heat-conducting fluid is introduced into the fluid channel 42 for heating and temperature regulation of the die.

[0029] In one embodiment, the fluid channel 42 is a spiral channel arranged to spiral around the axis of the mold core 2.

[0030] In this embodiment, refer to Figure 2 and Figure 3 This design not only has a homogenizing effect—the spiral flow effectively disrupts the original flow front of the melt, eliminating the "memory effect" and making the temperature and composition of each part of the melt more uniform—but also establishes stable pressure. The spiral flow channel helps to form a stable and continuous pressure field, providing a stable foundation for subsequent extrusion molding.

[0031] In one embodiment, the spiral diverter sleeve 4 is provided with a heat-conducting fluid inlet 43 and a heat-conducting fluid outlet 44 that communicate with the fluid channel 42. The heat-conducting fluid inlet 43 and the heat-conducting fluid outlet 44 extend to the outside of the mold body 1 for connecting to an external temperature control device 6.

[0032] In this embodiment, refer to Figure 2 and Figure 3 An external temperature control device (oil temperature controller) 6 pumps heated or cooled heat transfer oil into the fluid channel 42 from the heat transfer fluid inlet 43. The heat transfer oil flows within the spirally coiled channel, efficiently and evenly transferring heat to the spiral distribution sleeve 4 through the metal wall. Since the spiral distribution sleeve 4 is in direct contact with the polymer melt flow channel, heat can act quickly and directly on the melt itself, achieving rapid heating or heat preservation.

[0033] In one embodiment, the fluid channel 42, the heat-conducting fluid inlet 43, and the heat-conducting fluid outlet 44 constitute an independent temperature control unit; at least two temperature control units are arranged along the mold head axis to achieve independent temperature control of different areas of the mold head.

[0034] In this embodiment, refer to Figure 2 and Figure 3 This zoned independent temperature control can perfectly adapt to the temperature requirements of the melt at different stages during the flow process, thereby achieving zoned temperature control.

[0035] In one embodiment, a cylindrical electric heating coil 5 is provided on the outside of the mold head body 1.

[0036] In this embodiment, refer to Figure 1 The cylindrical electric heating coil 5 is wrapped around the outside of the die head body 1 as an auxiliary heating source, responsible for heating the entire die head to the approximate temperature range set by the process, and compensating for the heat loss of the die head to the environment.

[0037] In one embodiment, the circulating heat transfer fluid is heat transfer oil.

[0038] In this embodiment, refer to Figure 3 The heat transfer oil has a large heat capacity and high heat transfer efficiency. The temperature rise and fall of the mold head is much faster than that of the heating coil alone, which shortens the downtime for start-up and material replacement.

[0039] Working principle: High-temperature, low-smoke, halogen-free melt from the extruder enters the die body 1 through melt inlet 11. The melt first enters the outer spiral flow channel 41 formed between the spiral flow divider sleeve 4 and the inner wall of the die body 1. In this outer spiral flow channel 41, the melt is forced to advance along the spiral path.

[0040] After being homogenized and pressurized by the outer spiral flow channel 41, the melt continues to flow forward, passing through the annular gap formed by the mold core 2 and the mold sleeve 3, and is finally squeezed and shaped, covering the cable conductor or core wire to form a complete, dense, and uniformly thick insulation layer or sheath layer.

[0041] Inside the spiral distributor sleeve 4, one or more independent, closed fluid channels 42 are provided. Heat transfer oil (or other heat transfer fluid) circulates within these channels. Heating mode: When the die temperature is lower than the set value, the external temperature control device (oil temperature controller) 6 pumps heated high-temperature heat transfer oil from the heat transfer fluid inlet 43 into the fluid channel 42. The heat transfer oil flows within the spirally coiled channel, efficiently and evenly transferring heat to the spiral distributor sleeve 4 through the metal wall. Because the spiral distributor sleeve 4 is in direct contact with the polymer melt flow channel, heat can act quickly and directly on the melt itself, achieving rapid heating or heat preservation. Cooling mode: Because low-smoke halogen-free materials are temperature sensitive, local temperatures may become excessively high during high-speed extrusion or when frictional heating is severe. At this time, the external temperature control device (oil temperature controller) 6 can switch to cooling mode, pump low-temperature heat transfer oil into the fluid channel 42 to absorb excess heat in the die head, and bring it back to the temperature control device (oil temperature controller) from the heat transfer fluid outlet 44 for cooling, thereby achieving active cooling of the die head and preventing the material from overheating and decomposing.

[0042] When multiple independent temperature control units (i.e., multiple independent fluid channels) are set along the die head axis, independent temperature control for each zone can be achieved. For example, a higher temperature can be set for the section near the melt inlet 11 to reduce the melt viscosity, while a slightly lower temperature can be set for the shaping section near the outlet to facilitate shaping. This precise control can perfectly adapt to the temperature requirements of the melt at different stages during the flow process, thereby achieving zoned temperature control.

[0043] In summary, the polymer melt is physically homogenized in the spiral flow channel. At the same time, a composite temperature control system consisting of circulating heat transfer oil and external electric heating provides precise and uniform thermal management of the melt flow channel from the inside to the outside, ensuring that the melt is always within the optimal processing temperature window.

[0044] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A uniform temperature die head structure for a low-smoke halogen-free cable extruder, comprising a die head body (1), a die core (2) and a die sleeve (3) disposed within the die head body (1), wherein the die head body (1) is provided with a melt inlet (11). Its features are: The outer side of the mold core (2) is fitted with a spiral flow divider sleeve (4), and an outer spiral flow channel (41) for passing polymer melt is formed between the spiral flow divider sleeve (4) and the inner wall of the mold head body (1); the spiral flow divider sleeve (4) is provided with an independent closed fluid channel (42), and circulating heat-conducting fluid is introduced into the fluid channel (42) for heating and temperature regulation of the mold head.

2. The uniform temperature die structure of the low-smoke halogen-free cable extruder according to claim 1, characterized in that: The fluid channel (42) is a spiral channel arranged around the axis of the mold core (2).

3. The uniform temperature die structure of the low-smoke halogen-free cable extruder according to claim 2, characterized in that: The spiral diverter sleeve (4) is provided with a heat-conducting fluid inlet (43) and a heat-conducting fluid outlet (44) that communicate with the fluid channel (42). The heat-conducting fluid inlet (43) and the heat-conducting fluid outlet (44) extend to the outside of the mold body (1) for connecting to an external temperature control device (6).

4. The uniform temperature die structure of the low-smoke halogen-free cable extruder according to claim 3, characterized in that: The fluid channel (42), the heat-conducting fluid inlet (43), and the heat-conducting fluid outlet (44) constitute an independent temperature control unit; at least two of the temperature control units are arranged along the mold head axis to realize independent temperature control of different areas of the mold head.

5. The uniform temperature die structure of the low-smoke halogen-free cable extruder according to claim 1, characterized in that: The outer side of the mold head body (1) is provided with a cylindrical electric heating coil (5).

6. The uniform temperature die structure of the low-smoke halogen-free cable extruder according to any one of claims 1-5, characterized in that: The circulating heat transfer fluid is heat transfer oil.

Images