Internal refrigeration cable extruder head

Abstract

The invention relates to a kind of extrusion machines.The purpose is to provide a kind of inner refrigeration cable extrusion head, which should be able to cool the inside and outside of the sheath simultaneously, so as to eliminate the defects of uneven stress on the inside and outside of the sheath, and improve the product quality.The technical scheme is a kind of inner refrigeration cable extrusion head, including head and mold installed in the head body;The characteristics are that:two flow channels are opened on the head, which pass through the mold and are respectively aligned with the cable core channel in the mold core hole, and the outside of the two flow channels is respectively connected with air blowing device and air suction device, so as to introduce cooling air flow acting on the inside of the sheath in the mold core hole, and realize the purpose of cooling the inside of the sheath.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of extrusion machines, specifically is the inner refrigeration cable extrusion head. BACKGROUND

[0002] With the continuous development of cable industry, cable and optical cable gradually become the best medium for connecting the world, not for people to provide energy and information transmission tool, with the rapid development of cable industry, various types of cable emerge in endlessly, and most of the cable is formed by extrusion, mainstream extrusion molding is mainly completed by extrusion machine, head and die cable sheath processing sizing.

[0003] In cable production, such as cable core and sheath material is similar, it is easy to stick together during extrusion, causing product quality problems. At present, most cable manufacturers sheath cooling method is water cooling (i.e. the sheath formed by the head die is immediately put into the cooling water tank, so as to cool the outside of the sheath). But this way makes the inside and outside of the sheath cooling time is inconsistent. The reason is that the sheath is thick, the outside surface of the sheath can be cooled quickly, while the inside of the sheath cannot be cooled quickly, and the cooling time can reach 24h or even longer. This inconsistent cooling speed is easy to cause uneven stress on the inside and outside of the sheath, which is a cause of environmental stress cracking of the sheath in the later period. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the above background technology, and to provide an inner refrigeration cable extrusion head, which can cool the inside and outside of the sheath at the same time, so as to eliminate the uneven stress on the inside and outside of the sheath and improve the product quality.

[0005] The technical solution adopted by the present application is:

[0006] An inner refrigeration cable extrusion head, comprising a head and a die installed in the main body of the head. Its features are that two flow channels are provided on the head, which pass through the die and are aligned with the cable core channel in the die core hole. The outside of the two flow channels is connected with the blowing device and the suction device respectively, so as to introduce the cooling gas flow acting on the inside of the sheath in the die core hole, realizing the purpose of cooling the inside of the sheath.

[0007] Two inclined grooves are provided on the distribution cone, and two die core holes are provided on the die core. The two flow channels are connected with the right end of the cable core channel in sequence after communicating with the inclined grooves and the die core holes respectively, so as to realize effective cooling of the inside of the sheath.

[0008] The inner wall surface of the flow channel is coated with heat insulation material to avoid the influence of cooling gas convection on the temperature field distribution of the head, and to avoid quality problems of the cable sheath.

[0009] The heat insulation material is an insulating ceramic material.

[0010] The cooling gas is an inert gas.

[0011] The blowing device is a liquefied nitrogen bottle.

[0012] The suction device is a suction pump.

[0013] The working principle of the present application is that two flow channels are opened on the outside of the head, the assembly position of the mold core and the position of the opening on the inside of the head flow channel are connected through the inclined groove on the distribution cone; the mold core is provided with a mold core hole (one flow channel is aligned with the outside of the mold core hole through the inclined groove of the distribution cone, and the other flow channel is aligned with the inside of the mold core hole through the inclined groove of the distribution cone) which communicates with the inclined groove and the cable core channel, and the other outlets of the two flow channels are connected with the blowing device and the suction device respectively. By continuously injecting inert cooling gas and sucking out the gas, convection is formed at the central position of the mold core hole (the right end of the cable core channel), so as to achieve the purpose of cooling the extruded material; since the inside and outside of the sheath are cooled at the same time, the consistency of the cooling shrinkage stress of the sheath is ensured, thereby improving the anti-cracking performance of the product; and the adhesion phenomenon between the cable core and the outer sheath can be effectively avoided, and the cable quality is improved.

[0014] The beneficial effects of the present application are that the present application optimizes the design of the extruder head structure, forms convection by the inflow and outflow of cold air, cools the inside of the extruded sheath, and acts together with the outside water cooling to avoid uneven stress between the inside and outside of the sheath caused by local rapid cooling, thereby improving the environmental stress cracking resistance of the sheath; and when the internal refrigeration effect is exerted, the adhesion problem between the homogeneous or similar cable core and the sheath can also be improved at the same time, the quality risk is reduced, and the quality of the sheath is improved; in addition, inert gas (preferably nitrogen) is used, which is low in cost and pollution-free, and is an excellent solution to improve the sheath. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the cross-sectional structure of an embodiment of the present application.

[0016] Figure 2 is Figure 1 is an enlarged schematic diagram of the structure of the mold part (i.e., a schematic diagram of the flow direction of the cooling gas).

[0017] Reference numerals in the figure: 1. head; 2. biasing screw; 3. mold sleeve; 4. mold core; 5. heating element; 6. first flow channel; 6-1. first flow channel outside opening; 7. second flow channel; 7-1. second flow channel outside opening; 8. cable core channel; 9. cooling water tank; 10. sheath; 11. distribution cone; 12. mold base; 13. gland; 14. temperature sensor; 15. feeding channel; 16. first mold core hole; 17. second mold core hole. DETAILED DESCRIPTION

[0018] The embodiments shown in the accompanying drawings are further described below.

[0019] The inner refrigeration cable extrusion head shown in the accompanying drawings is made of high-temperature-resistant steel, and is provided with a heating element 5 (preferably an electric heating wire) at the bottom for heating the head and controlled by a PLC. The middle cavity is inlaid with a mold. The left end of the mold is connected to a horizontally arranged cable core passage 8 (the left end of the cable core passage is the cable core inlet), and the right end of the mold is the extrusion outlet (the sheath extruded on the surface of the cable core is pulled out of the outlet together with the cable core, and then enters the cooling water tank 9 for cooling).

[0020] The mold is externally covered by a material distribution cone 11, which is connected to a feeding passage 15 provided in the head. The inlet of the feeding passage is provided on the side of the head and is connected to an extruder. The molten plastic output by the extruder is shaped into a mold sleeve shape and wrapped around the outer surface of the cable core after passing through the feeding passage 15 (the feeding passage sequentially penetrates the head, the material distribution cone, the mold core 4, and the mold sleeve 3).

[0021] The mold includes a mold core 4 in the center, a mold seat 12 on the right side of the mold core, a mold sleeve 3 fixed in the inner hole of the mold seat (the mold sleeve is sleeved on the right side of the mold core to fix the mold core in the cavity of the head), and a gland 13 pressing and fixing the mold sleeve on the head (the extrusion outlet is provided in the middle of the gland). Four biasing screws (two biasing screws are shown in the figure, and the biasing screws on the left and right sides are omitted) are provided on the head, and the biasing degree of the sheath can be adjusted and controlled by the biasing screws 2.

[0022] The temperature sensor 14 is used to detect the temperature of the head. When the temperature is lower than the set temperature, the PLC-controlled heating element is started. After reaching the set temperature, the PLC-controlled heating element is turned off, so as to keep the temperature of the head within a certain range.

[0023] The above structure is similar to the existing cable extrusion head.

[0024] The improvement of the application is that two flow channels are formed on the head, the slanting grooves corresponding to the flow channels are formed on the distributing cone, the core holes corresponding to the slanting grooves are formed on the core, the outer opening of one flow channel (the second flow channel 7) is connected with the blowing device (preferably a liquefied nitrogen bottle) outside the head, and the inner opening is connected with the right end of the cable core channel (close to the extrusion outlet) through a slanting groove on the distributing cone and the second core hole 17 in sequence; the outer opening of the other flow channel (the first flow channel 6) is connected with the suction device (preferably a suction pump) outside the head, and the inner opening is also connected with the right end of the cable core channel (close to the extrusion outlet) through the other slanting groove on the distributing cone and the first core hole 16 in sequence. When the blowing device and the suction device work together (see Figure 2 ), the cooling gas flows through the right end of the cable core channel, the extrusion outlet, absorbs heat and becomes hot gas, and then returns to the cable core channel; part of the hot gas is discharged to the outside of the head through the first flow channel, and the other part of the hot gas escapes from the inlet of the cable core channel (through the gap between the wall of the cable core channel and the outer circumference of the cable core). When the head works, the sheath material in a molten state is formed into a sheath (the cross section of the sheath is a circular ring) at the junction of the core 4 and the mold sleeve 3, and the inner side of the sheath faces the axis of the cable core channel; therefore, the cooling gas directly takes away part of the heat of the inner side of the sheath (the arrow shows the direction of the gas flow), thereby reducing the temperature of the inner side of the sheath. Figure 1

[0025] As a recommendation, the inner wall of the two flow channels is also coated with a layer of heat insulation material (as a recommendation, the heat insulation material is preferably an insulating ceramic material), so as to avoid the heat in the head being taken away by the cooling gas, thereby affecting the temperature field distribution of the head (if the temperature of the head decreases, the sheath material in a molten state in the mold tends to solidify quickly, thereby affecting the flowability of the sheath material), thereby causing quality problems of the cable sheath.

[0026] The working principle of the application is that the cooling gas blows the inner side of the sheath through the head and the cavity of the mold, absorbs heat and becomes hot gas, and then is discharged outward, thereby achieving cooling of the inner side of the sheath; the outer side of the sheath still adopts the cooling water (9) mode to cooperate with each other, so that the cooling speed of the inner and outer sides of the sheath is close, thereby avoiding stress uneven caused by local cooling, improving the quality of the sheath and improving the stress cracking resistance of the sheath; and the cooling of the inner sheath can also avoid the adhesion of the sheath and the cable core, thereby greatly improving the product quality. The heat insulation material (6) is coated on the inner walls of the two flow channels, which can prevent the heat in the head from being lost through the flow channels (conduction and convection of heat in the flow channels). ​

[0027] As preferred, the cooling gas adopts nitrogen, which is close to air density, has good refrigeration effect, is pollution-free and low in cost.

[0028] As preferred, the heat insulation material layer is preferably selected from insulating ceramic materials. The coating process of the insulating ceramic materials is a prior art, which is not described here in detail.

[0029] As preferred, the gland adopts a threaded fixing structure.

[0030] As preferred, the material cone adopts die steel and is plated with chromium, so as to avoid corrosion of the material cone by plastic and prolong the service life.

[0031] Characteristics of the present application:

[0032] 1. The inner refrigeration cable extrusion head adopts high-performance die steel, which is high in temperature resistance and does not deform at high temperature.

[0033] 2. The head cooling gas channel is coated with heat insulation material, so as to avoid heat conduction of the head into the cooling gas and also avoid the influence of the cooling gas on the head temperature and thus on the sheath.

[0034] 3. The cooling gas adopts inert gas, which does not cause adverse effects on the sheath. The inert gas is preferably nitrogen, which is convenient to obtain, low in price, close to air density and good in refrigeration effect.

[0035] 4. The inner refrigeration cable extrusion head inner material cone adopts high-performance die steel and is plated with chromium, so that the contact surface with the sheath material is not easy to corrode, and the service life is greatly prolonged.

[0036] 5. The inner refrigeration cable extrusion head produced sheath is cooled almost simultaneously inside and outside, which can avoid stress unevenness caused by local cooling to the greatest extent, improve the sheath strength, elongation and environmental stress cracking resistance, and is an optimal solution for high-performance sheath production.

[0037] The above is a detailed introduction to the inner refrigeration cable extrusion head provided by the present application. For general manufacturers in the field, there will be changes in specific implementation and application range according to the idea and principle of the embodiment of the present application. Therefore, the content of the specification should not be understood as a limitation of the present application.

Claims

1. An internally refrigerated cable extrusion head comprising a head (1) and a die mounted in the head body; characterized in that: Two flow channels are formed on the head and pass through the mold and align with the cable core channels in the mold core holes, and the outer sides of the two flow channels are respectively connected with the air blowing device and the air suction device, so that the cooling gas acting on the inner side of the sheath (10) is introduced into the mold core hole, and the purpose of cooling the inner side of the sheath is achieved; The mold comprises a mold core (4) in the center, a mold base (12) on the right side of the mold core, a mold sleeve (3) fixed in the inner hole of the mold base, and a pressure cover (13) pressing the mold sleeve and fixing it on the head under pressure; Two inclined grooves are formed on the distribution cone, and two mold core holes are formed on the mold core; the two flow channels are respectively communicated with the inclined grooves and the mold core holes in sequence and then pass through the right end of the cable core channel, so that the inner side of the sheath is effectively cooled; The inner wall surface of the flow channel is coated with a heat insulation material layer. The heat insulation material layer is an insulating ceramic material.

2. The internally refrigerated cable extrusion head of claim 1, wherein: The cooling gas is an inert gas.

3. The internally refrigerated cable extrusion head of claim 2, wherein: The air blowing device is a liquefied nitrogen gas bottle.

4. The internally refrigerated cable extrusion head of claim 3, wherein: The air suction device is an air suction pump.

5. The internally refrigerated cable extrusion head of claim 4, wherein: ​

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