A double-layer double-color cable extrusion die

Abstract

The application discloses a double-layer double-color cable extrusion die, relates to the technical field of cables, and comprises a die core, a large die sleeve and a small die sleeve. The die core is inserted into the large die sleeve to form an extrusion groove for the flow of glue material. The large die sleeve is fixedly connected with a flow divider, and the small die sleeve is rotatably connected to the large die sleeve. An injection hole, a first flow dividing groove and a second flow dividing groove are arranged on the large die sleeve and arranged in a circumferential direction. A total flow dividing groove is further arranged on the circumferential surface of the flow divider, and the injection hole is communicated with the total flow dividing groove. A first flow guiding groove and a second flow guiding groove are arranged on the small die sleeve, and the first flow dividing groove and the second flow dividing groove are communicated to the extrusion groove through the first flow guiding groove and the second flow guiding groove, respectively. When it is required to change the coverage of coloring material on the cable, the small die sleeve is rotated to change the communication area of the flow guiding groove and the flow dividing groove, so that the coloring width of the cable is changed. Therefore, the same head can be used to produce cables with different requirements without large modification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable, in particular to a double-layer double-color cable extrusion die. BACKGROUND

[0002] The color of the insulation of the wire and cable needs to be identified (red, yellow, green, blue, black, etc.) due to the power supply phase requirement. However, the insulation coloring requirements of the cable in different application fields are different. For example, in the field of automotive cables, the insulation core is divided into primary color and secondary color, and the laying requirement adopts two symmetrical color strips covering each other, each covering at least 7%, and the total coverage is not more than 35%. In the field of building electrical assembly, the protective grounding wire is yellow-green double color, and the proportion is 30%-70%. In the field of robot cables, the insulation color requirement is to use one or two different colors to identify the combination color. In addition, the specific proportion of the color coverage is different for different customers.

[0003] In the cable manufacturing industry, when producing cables for different fields and different customer requirements, different dies and machine heads need to be prepared according to the different insulation colors and color coverage rates. When switching, the machine head and die need to be cleaned, the glue needs to be re-discharged, and the die needs to be re-adjusted, which not only wastes materials but also wastes time. It brings difficulties to the production and batch production. For 450 / 750V and below wire fields, the current industry is promoting double-layer extrusion, that is, the outer layer of the insulation is colored by a small extruder, and the inner layer is extruded by the main machine. When switching colors, only the glue of the small extruder needs to be discharged, and the glue of the main machine does not need to be discharged, so as to save materials and shorten the processing preparation time. In order to achieve this effect, the current mature solution is to set two flow dividers in the machine head, and the two flow dividers are coaxially placed on both sides of the machine head inlet and outlet. The length of the machine head is twice as long as the current single-layer extrusion machine head. That is, the single-layer extrusion is changed to double-layer extrusion, which often needs to redesign the machine head, the cost is high, and the improvement and assembly process of the machine head will inevitably delay the production of the current equipment. The enthusiasm of various cable enterprises for the improvement of the existing extruder is not high. In summary, according to the different insulation colors and color coverage rates, different dies and machine heads need to be prepared, the machine head and die need to be cleaned, the glue needs to be re-discharged, and the die needs to be re-adjusted when switching. The following problems need to be solved:

[0004] 1. Multiple dies and machine heads need to be prepared, and the hardware investment is high.

[0005] 2. Due to the use of multiple dies, it is easy to make mistakes during production.

[0006] 3. When switching dies, the glue needs to be re-discharged and the die needs to be re-adjusted, which takes a long time to process and prepares and wastes a lot of materials.

[0007] 4. The improvement of the traditional single-layer extruder to double-layer extrusion effect needs to update the machine head, which needs a large investment. SUMMARY

[0008] This application provides a two-color double-layer cable extrusion die, which adopts the following technical solution:

[0009] A double-color, double-layer Xi'an cable extrusion die, comprising a die core, a large die sleeve, and a small die sleeve; the die core is used to be inserted into the large die sleeve to form an extrusion groove for the flow of rubber material therebetween; a diverter is fixedly connected to the large die sleeve, and the small die sleeve is rotatably connected to the large die sleeve, with the rotation axis of the small die sleeve arranged along its own axis direction;

[0010] The large mold sleeve is provided with an injection hole for the colorant to flow in, and the end surface of the diverter is provided with a first diverter groove and a second diverter groove for the colorant to flow out, wherein the first diverter groove and the second diverter groove are arranged along the circumferential direction; the circumferential surface of the diverter is also provided with a main diverter groove for driving the colorant to flow into the first diverter groove and the second diverter groove respectively, and the injection hole is connected to the main diverter groove;

[0011] The small die sleeve is provided with a guide groove 1 and a guide groove 2 along the circumferential direction, and the guide groove 1 and the guide groove 2 are respectively connected to the diversion groove 1 and the diversion groove 2; the small die sleeve rotates to change the total length of the connection; the guide groove 1 and the guide groove 2 are both connected to the extrusion groove.

[0012] Furthermore, the large mold sleeve is connected to a locking cover via threads, and the small mold sleeve is located between the large mold sleeve and the locking cover; the locking cover is also provided with a handle.

[0013] Furthermore, the total diversion groove is a semicircular arc groove; the injection hole is connected to the midpoint of the total diversion groove, and a diversion tooth 1 is provided at the midpoint of the total diversion groove; the two end points of the total diversion groove are respectively provided with a diversion tooth 2 and a diversion tooth 3.

[0014] Furthermore, the diverter groove 1 and the diverter groove 2 are respectively connected to the two end points of the total diverter groove, and the diverter groove 1 and the diverter groove 2 are respectively arranged on the two end surfaces of the diverter, and the projections of the diverter groove 1 and the diverter groove 2 in the axial direction overlap.

[0015] Furthermore, the diversion trough 1 and the diversion trough 2 are both provided with overflow weirs with gradually changing heights; the height of the overflow weirs gradually decreases from both ends to the middle.

[0016] Furthermore, the width of the guide groove 1 and the guide groove 2 is equal to the average width of the diversion groove 1 or the diversion groove 2; and a chamfer is provided at the point where the guide groove 1 and the guide groove 2 are connected to the extrusion groove.

[0017] Furthermore, the end surface of the large mold sleeve is provided with scale lines; the end surface of the small mold sleeve is provided with a pointer and a hexagonal hole.

[0018] Furthermore, the diverter is provided with a threaded hole along its radial direction, the large die sleeve is provided with a threaded hole along its radial direction, and the diverter is fixedly connected to the large die sleeve by positioning bolts.

[0019] Furthermore, a through hole is provided on the positioning bolt, and a guide groove three is provided on the diverter; the through hole is connected to the guide groove three, and the guide groove three is connected to the extrusion groove.

[0020] Furthermore, a heating ring is provided on the locking cover.

[0021] In summary, this application has the following beneficial technical effects:

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Unlike traditional extruders that design the diverter inside the die head, this patent sets the diverter directly inside the die sleeve, and the material flow diversion direction is changed from the traditional horizontal direction of cable production to perpendicular to the cable production direction; using this structure does not require increasing the die head length, and the original single die head can be used to complete double-layer extrusion of wires.

[0024] 2. The present invention designs a new type of gradual deflector, which can divide the material flow into two upper and lower half circles and distribute them more evenly into a full circle, thereby providing an extrusion basis for double-layer extrusion.

[0025] 3. The present invention comprehensively considers the requirements of double-layer extrusion and double-color extrusion. By adjusting the overlap of the glue outlet of the diverter and the small mold sleeve, a set of molds can produce cables with any coloring ratio, avoiding the cable companies from repeatedly switching molds when producing products and shortening the production preparation time.

[0026] 4. This patent adopts a structure in which the positioning bolt is made into a central through-hole structure, and a guide groove three is set along the outer edge of the small mold sleeve. A glue injection port is set in the groove, which is smaller than the width of the groove. The cross-section of the glue injection port is equal to the through-hole of the fixing bolt. Guide groove three should be on the same side as guide groove two. The second color material is injected through another glue injection machine. During production, the first color material is covered on the main material through guide groove two, and the second color material is covered on the first color material through guide groove three. If the production of double-layer + double-color products is not required, the positioning bolt in the central through-hole can be replaced with a solid positioning screw, realizing the multi-purpose use of one mold.

[0027] 5. A smaller mold sleeve can be designed inside the small mold sleeve. When used with the small mold sleeve, it can reduce mold manufacturing costs and quickly replace molds.

[0028] 6. Traditional mold replacement requires downtime to clean the mold head and readjust the eccentricity, which takes one to two hours. This design, however, can be completed in seconds, reducing the loss of polymer material during commissioning. Production efficiency is greatly improved. Switching between different coloring widths requires only loosening the mold sleeve fastening cover and rotating the small mold sleeve to produce products of different coloring widths.

[0029] 7. Low implementation cost. The improvement of this application only requires changing the mold core and mold sleeve, which is a small change and low cost. Compared with the cost of 50,000 to 100,000 yuan to improve the double-layer extrusion head, this patent can be used on a single-layer head only by improving the mold sleeve to achieve the double-layer extrusion effect, and the cost is less than 5% of the head modification fee.

[0030] 8. Highly versatile: The design concept of this application is applicable to mold improvements for most common plastic extrusion production lines, such as 70, 80, 90, 120, and 150 extruders. It is also suitable for common cable polymer materials such as polyethylene, polyvinyl chloride, cross-linked polyethylene, polyolefins, and nylon.

[0031] 9. Low mold cost. Compared with traditional double-layer and double-color products that require the production of a large number of mold sets, this design only requires one set of molds, greatly reducing mold manufacturing costs and management costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the overall structural diagram of a double-layer, double-color cable extrusion die in this application;

[0033] Figure 2 This is an exploded view of the overall structure of a double-layer, double-color cable extrusion die in this application;

[0034] Figure 3 Figure 1 is a cross-sectional view of the overall structure of a double-layer, double-color cable extrusion die in this application;

[0035] Figure 4 yes Figure 2 The overall structure diagram of the middle diverter and small mold sleeve;

[0036] Figure 5 yes Figure 2 The overall structure of the middle diverter and small mold sleeve from another perspective.

[0037] Description of reference numerals:

[0038] 1. Mold core; 11. Extrusion groove; 2. Large mold sleeve; 21. Injection hole; 3. Diverter; 31. Main diverter groove; 32. Diverter groove one; 33. Diverter groove two; 34. Diverter tooth one; 35. Diverter tooth two; 36. Diverter tooth three; 38. Overflow weir; 4. Small mold sleeve; 41. Diverter groove one; 42. Diverter groove two; 43. Diverter groove three; 44. Rotary adjustment hole; 5. Locking cover; 51. Handle; 6. Heating coil; 7. Positioning bolt; 71. Through hole. DETAILED DESCRIPTION

[0039] The following is combined with Figure 1-5 This application is described in further detail.

[0040] The present application discloses a double-layer double-color cable extrusion die, which can realize double-color double-layer cable extrusion, is applicable to a variety of machine heads, and does not require major modifications to the machine heads; the die comprises a die core 1, a large die sleeve 2 and a small die sleeve 4; similar to the existing die, the die core 1 is inserted into the large die sleeve 2, and an extrusion groove 11 is formed between the two; a diverter 3 is fixedly connected to the large die sleeve 2 by a positioning bolt 7, and the positioning bolt 7 is arranged in the radial direction of the diverter 3; the small die sleeve 4 is rotatably connected to the large die sleeve 2; an injection molding machine is provided on the large die sleeve 2 in the radial direction The inlet hole 21 and the circumference of the diverter 3 are provided with an arc-shaped main diverter groove 31, which is connected to the diverter groove 1 32 and the diverter groove 2 33. The two end surfaces of the small die sleeve 4 are respectively provided with a guide groove 1 41 connected to the diverter groove 1 32 and a guide groove 2 42 connected to the diverter groove 2 33. The guide groove 1 41 and the guide groove 2 42 are ultimately connected to the extrusion groove 11. The colorant flows from the injection hole 21 into the diverter 3 and finally enters the extrusion groove 11 through the guide groove 1 41 and the guide groove 2 42, thereby achieving the double color strip extrusion of the cable. When the color strip coverage needs to be changed, the small die sleeve 4 is rotated to change the connectivity between the guide groove 1 41 and the diverter groove 1 32, and the connectivity between the guide groove 2 42 and the diverter groove 2 33, thereby changing the color strip coverage, that is, the width.

[0041] To facilitate the rotation of the small die sleeve 4, a locking cap 5 is threadedly connected to the large die sleeve 2. The large die sleeve 2 is provided with an internal thread, and the locking cap 5 is provided with an external thread. The locking cap 5 is connected to the large die sleeve 2, and the small die sleeve 4 is pressed against the large die sleeve 2. A hexagonal wrench adjustment hole 44 is provided on the small die sleeve 4. The small die sleeve 4 can be rotated by inserting a hexagonal wrench into the adjustment hole 44.

[0042] The diverter 3 is a circular ring with a main diverter trough 31 located along its outer cylindrical surface. The central angle of this main diverter trough 31 is 180°. A diverter tooth 1 34 is located in the center of this main diverter trough 31, dividing the colored material flow into two left and right streams. Diverter trough 1 32 and diverter 2 33 are located on the sides of the cylinder. The central angles of diverter trough 1 32 and diverter 2 33 are 180° and 190°, respectively. Diverter teeth 2 35 and 36 are located at the left and right ends of the main diverter trough 31. Both diverter teeth 35 and 36 have arcs and fillets on their sides to guide the material flow in the direction of the diverter teeth. The left and right materials are evenly divided again by the second diverter tooth 35 and the third diverter tooth 36 to form four material flows, two of which flow along the diverter groove 1 32 and merge in the middle of the diverter groove 1 32; the other two flow along the diverter groove 2 33 and merge.

[0043] The schematic diagram of the diverter 3 is shown in FIG4 ; the diverter slot three is 10° wider than the diverter slot two 33 because diverter teeth two 35 , diverter teeth three 36 and a guide arc need to be provided here, and at the same time, the material flows of the two semicircles are partially overlapped, that is, the projections in the axial direction are partially overlapped.

[0044] In order to enhance the smoothness of the flow of the coloring material, the diverter trough 1 32 and the diverter trough 2 33 are provided with a gradual overflow weir 38, the height of the overflow weir 38 gradually decreases from the two ends to the middle, that is, the outflow cross-section gradually increases from the two ends to the middle of the flow channel, that is, the diverter trough 1 32 and the diverter trough 2 33 both have a slope, the purpose of which is to compensate for the decrease in flow velocity when the material flows from the two ends to the middle along the flow channel, thereby ensuring that the material flows out of the two semicircular overflow weirs 38 of the diverter trough 1 32 and the diverter trough 2 33 to form a relatively uniform annular coloring layer.

[0045] Since the volume of molten plastic after extrusion through the extruder is considered uncompressed within the flow channel, the law of conservation of volumetric flow states: Sv = constant, where S is the outflow cross-section and V is the outflow velocity. When the total area of ​​the outflow holes equals the total cross-section of the diverter channel 31, the average outflow velocity through the diverter channel 31 equals the velocity of the material flow. Fluid flow due to material flow will experience pressure losses along the flow direction (along-the-line pressure loss, local pressure loss, and pressure loss in the flow reduction zone), gradually decreasing along the flow direction. According to the Poiseuille equation for flow, flow rate is directly proportional to the pressure difference and inversely proportional to the flow path L. As pressure decreases along the flow direction, flow rate also decreases. Flow rate Q = flow velocity V * outflow cross-section S. When the outflow cross-section S remains constant, a decrease in flow rate indicates a gradual decrease in flow velocity. Using outlet holes with uniform cross-sections results in a gradual decrease in flow rate, which does not meet the requirements for producing a uniform colored layer. Since the change in pressure is affected by many factors such as material viscosity, flow channel size changes, temperature, etc., it is difficult to find the formula relationship between flow rate and flow path.

[0046] In order to make the thickness of the extruded colored layer as uniform as possible, the flow rate along the annular flow outlet needs to be as uniform as possible. Although the formula relationship between flow velocity and flow path is difficult to determine, the trend of flow velocity decreasing with increasing flow distance is clear (it’s just that this decreasing trend is not linear, but a curve). The present application gradually increases the flow outlet to compensate for the decrease in flow velocity, and designs the width of the outflow hole to be in a proportional linear relationship with the flow distance along the diverter trough 1 32 and the diverter trough 2 33. When setting the flow outlet, in order to ensure that the extruded colored material flow is not blocked here, the minimum width cannot be 0. For conventional cable material PVC, it can be designed to be 0.05-1mm. The maximum process port width is determined according to the total cross-section of the flow outlet. During design, the total cross-section of the semicircular outlet should be ≤ the cross-section of diverter trough 1 32 and diverter 2 33 ≤ half the total diverter trough 31 . That is, the lengths of diverter trough 1 41 and diverter 2 42 should be equal to the lengths of diverter trough 1 32 and diverter 2 33 , respectively. This increases the dynamic pressure of the material flow, allowing the material flow to be more tightly combined in the center, thus avoiding the formation of glue seams. As a color layer extrusion, cable product standards do not assess the uniformity of the color layer thickness. However, according to this patented design, the surface after coloring is smooth, meeting visual quality requirements.

[0047] To enhance the mold's robustness, a reinforcing rib is provided in the center of guide groove 1 (41). The rib is triangular in shape, larger on the outside and smaller on the inside. The outside corners should be rounded to facilitate the material flow to converge toward the center. The outlet widths of guide groove 1 (41) and guide groove 2 (42) are equal to the average width of diverter groove 1 (32) or diverter groove 2 (33) of diverter 3. A 45° chamfer is provided where guide groove 1 (41) and guide groove 2 (42) connect to the extrusion groove 11. The chamfer length is equal to the maximum outlet width of diverter 3 minus the outlet width. After the chamfer, a chamfer with the same radius is added, allowing the material flow at the maximum outlet width of diverter 3 to flow smoothly along the chamfer into the guide groove of the small die sleeve 4.

[0048] When the small die sleeve 4 is assembled with the diverter 3, the guide groove 1 41 and the guide groove 2 42 overlap with the diverter groove 1 32 and the diverter groove 2 33 respectively, forming a double-layer extrusion effect, and forming a double-color stripe effect when the angles are staggered.

[0049] To facilitate adjustment of the required rotation angle of the small die sleeve 4 based on the desired coverage, the large die sleeve 2 is equipped with scale lines. The end surface of the small die sleeve 4 is equipped with a pointer and a hexagonal rotation adjustment hole 44. A hexagonal wrench is used to rotate the adjustment hole 44. The guide groove 1 (41) should be positioned as far away from the die sleeve's sizing area (working surface) as possible to facilitate the compression of the colorant and main material within the mold through the core 1 and the die sleeve, ensuring a more uniform combination of the colorant and main material. The length of the sizing area of ​​the die sleeve 2 and the difference in taper angle between the core 1 and the die sleeve can also be appropriately increased to increase the extrusion pressure and facilitate a tighter combination of the colorant and main material.

[0050] Because this design extends the length of the mold sleeve as a whole, the temperature of the extended part will drop after leaving the machine head, affecting the plasticizing fluidity of the material flow. In order to maintain the temperature, a heating coil 6 is provided in the extended part of the mold sleeve; the heating coil 6 can be fixedly connected to the locking cover 5. As an accessory, the heating coil 6 is relatively easy to purchase.

[0051] Furthermore, in order to simultaneously produce double-layer, two-color cables (for example, double-layer yellow-green two-color wires), the inner layer is the original color main material, and the outer layer is the two-color coloring material. This application adopts the structure of making the positioning bolt 7 into a middle through hole 71, and setting a guide groove three 43 along the outer edge of the small mold sleeve 4 at 120 degrees. The groove is provided with a glue injection port that is smaller than the groove width, also at 120 degrees. The through hole 71 of the positioning bolt 7 is connected to the guide groove three 43, and the guide groove three 43 is connected to the extrusion groove 11; the guide groove three 43 should be on the same side as the guide groove two 42; the second color material is injected through another glue injection machine. During production, the first coloring material is covered on the main material (original color material) through the guide groove two 42, and the second coloring material is covered on the first coloring material through the guide groove three 43, and the coverage is 120 degrees (meeting the coloring coverage requirement of 30%-70% required by the product standard). If it is not necessary to produce a double-layer + double-color product, the positioning bolt 7 of the middle through hole 71 can be replaced with a positioning screw.

[0052] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A double-layer, double-color cable extrusion die, characterized by: The invention comprises a mold core (1), a large mold sleeve (2) and a small mold sleeve (4); the mold core (1) is used to be inserted into the large mold sleeve (2) to form an extrusion groove (11) between the two for the flow of rubber material; a diverter (3) is fixedly connected to the large mold sleeve (2); the small mold sleeve (4) is rotatably connected to the large mold sleeve (2), and the rotation axis of the small mold sleeve (4) is arranged along the direction of its own axis; The large die sleeve (2) is provided with an injection hole (21) for the colorant to flow in, and the end surface of the diverter (3) is provided with a diverter groove (32) and a diverter groove (33) for the colorant to flow out, and the diverter groove (32) and the diverter groove (33) are arranged along the circumferential direction; the circumferential surface of the diverter (3) is also provided with a main diverter groove (31) for driving the colorant to flow into the diverter groove (32) and the diverter groove (33) respectively, and the injection hole (21) is communicated with the main diverter groove (31); The small die sleeve (4) is provided with a guide groove 1 (41) and a guide groove 2 (42) along the circumferential direction, and the guide groove 1 (41) and the guide groove 2 (42) are respectively connected to the diversion groove 1 (32) and the diversion groove 2 (33); the small die sleeve (4) rotates to change the total length of the connection; the guide groove 1 (41) and the guide groove 2 (42) are both connected to the extrusion groove (11).

2. The double-layer double-color cable extrusion die according to claim 1, characterized in that: The large die sleeve (2) is connected to a locking cover (5) via threads, and the small die sleeve (4) is located between the large die sleeve (2) and the locking cover (5); the locking cover (5) is also provided with a handle (51).

3. The double-layer double-color cable extrusion die according to claim 1, characterized in that: The total diverter groove (31) is a semicircular arc groove; the injection hole (21) is connected to the midpoint of the total diverter groove (31); the midpoint of the total diverter groove (31) is provided with a diverter tooth 1 (34); the two end points of the total diverter groove (31) are respectively provided with a diverter tooth 2 (35) and a diverter tooth 3 (36).

4. The double-layer double-color cable extrusion die according to claim 3, characterized in that: The diverter groove 1 (32) and the diverter groove 2 (33) are respectively connected to the two end points of the main diverter groove (31), and the diverter groove 1 (32) and the diverter groove 2 (33) are respectively arranged on the two end surfaces of the diverter (3), and the projections of the diverter groove 1 (32) and the diverter groove 2 (33) in the axial direction overlap.

5. The double-layer double-color cable extrusion die according to claim 4, characterized in that: The first diversion trough (32) and the second diversion trough (33) are both provided with overflow weirs (38) with gradually changing heights; the heights of the overflow weirs (38) gradually decrease from both ends to the middle.

6. The double-layer double-color cable extrusion die according to claim 5, characterized in that: The width of the guide groove 1 (41) and the guide groove 2 (42) is equal to the average width of the diversion groove 1 (32) or the diversion groove 2 (33); the guide groove 1 (41) and the guide groove 2 (42) are connected to the extrusion groove (11) and a guide angle is provided.

7. The double-layer double-color cable extrusion die according to claim 1, characterized in that: The end surface of the large die sleeve (2) is provided with a scale line; the end surface of the small die sleeve (4) is provided with a pointer and a rotation adjustment hole (44).

8. The double-layer double-color cable extrusion die according to claim 1, characterized in that: The diverter (3) is provided with a smooth hole along its radial direction, and the large die sleeve (2) is provided with a threaded hole along its radial direction. The diverter (3) is fixedly connected to the large die sleeve (2) via positioning bolts (7).

9. The double-layer double-color cable extrusion die according to claim 8, characterized in that: A through hole (71) is provided on the positioning bolt (7), and a guide groove three (43) is provided on the small die sleeve (4); the through hole (71) is communicated with the guide groove three (43), and the guide groove three (43) is communicated with the extrusion groove (11).

10. The double-layer double-color cable extrusion die according to claim 2, characterized in that: The locking cover (5) is also provided with a heating ring (6).

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