A double color cable sheath feeding automatic control system

Abstract

The application provides a double-color cable sheath feeding automatic control system, which comprises a host extruder, an auxiliary extruder, a detection assembly and a control assembly; the detection assembly comprises a first detection unit, a second detection unit and a third detection unit; and the control assembly comprises a controller which is configured to: calculate a melt pressure difference based on a real-time pressure detected by the second detection unit and a preset pressure, calculate a temperature deviation based on a real-time temperature detected by the third detection unit and a preset process temperature, and control a speed of an auxiliary screw of the auxiliary extruder based on a real-time rotating speed of a host screw detected by the first detection unit, an electronic gear ratio, the melt pressure difference and the temperature deviation, so as to solve the problems of discontinuity, uneven thickness and poor adaptability of a color surface layer in the prior art, realize accurate automatic control of feeding amounts of different components of a double-color cable sheath, and improve product qualification rate and production efficiency.

Description

Technical Field

[0001] This invention relates to the field of cable processing technology, and in particular to an automatic control system for feeding two-color cable sheaths. Background Technology

[0002] Two-color cable sheaths (colored outer layer wrapped around the base layer of the original color) are a key structure for cable identification and safety protection, and are widely used in power transmission, electrical equipment and other fields. Their production core relies on the two-color co-extrusion process of the main and auxiliary extruders. The stability of the feed rate directly determines the uniformity and continuity of the thickness of the colored outer layer and the overall quality of the product.

[0003] Existing dual-color cable sheath feeding control systems generally adopt simple fixed proportional speed control. This control method cannot adapt to the dynamic disturbances during the feeding process. During dual-color co-extrusion, slight blockages and carbon buildup can easily occur in the flow channel of the auxiliary die head, or uneven plasticization of the raw materials can lead to fluctuations in melt pressure. These fluctuations directly change the melt volume flow rate of the auxiliary die. Using only a fixed speed to follow the flow rate cannot respond to pressure changes in real time. When the pressure increases, the melt flow rate decreases, resulting in a thinner and intermittent color layer; when the pressure decreases, the melt flow rate increases, resulting in a thicker color layer, ultimately causing uneven color layer thickness.

[0004] Furthermore, the raw materials for the sheath of dual-color cables are all non-Newtonian fluids, and their apparent viscosity changes significantly with temperature. As the temperature increases, the viscosity decreases, the melt flow rate increases at the same rotation speed, and the colored layer becomes thicker; as the temperature decreases, the viscosity increases, the melt flow rate decreases at the same rotation speed, and the colored layer becomes thinner and discontinuous. Existing control systems ignore the effect of temperature on viscosity, leading to a gradual shift in the colored layer during production due to temperature drift at the die head and changes in ambient temperature. Especially after prolonged production, the accumulation of temperature drift exacerbates the defects in the colored layer.

[0005] Finally, in the existing technology, some control systems use the main machine's set speed as a synchronization reference. Due to factors such as power grid fluctuations, load disturbances, and changes in traction speed during the production process, the actual speed of the main machine will deviate slightly from the set speed. If the auxiliary machine still follows according to the fixed set speed ratio, it will lead to an imbalance in the feeding ratio between the main and auxiliary machines, which in turn will cause fluctuations in the thickness of the color layer.

[0006] Therefore, those skilled in the art need to improve existing control systems to overcome the aforementioned deficiencies. Summary of the Invention

[0007] This invention provides an automatic control system for feeding two-color cable sheaths, which introduces pressure PID compensation, temperature compensation and real-time speed synchronization mechanism to solve the problems of discontinuous color layer, inconsistent thickness and poor adaptability in the prior art. It realizes precise automatic control of the feeding amount of two-color cable sheaths with different components, and improves product qualification rate and production efficiency.

[0008] To achieve the above objectives, in a first aspect, this application provides an automatic control system for feeding two-color cable sheaths, comprising: a main extruder for extruding the natural-colored base layer of the cable sheath, a secondary extruder for extruding the colored surface layer of the cable sheath, a detection component, and a control component; The detection assembly includes a first detection unit for detecting the main screw speed of the main extruder, a second detection unit for detecting the melt pressure of the auxiliary extruder, and a third detection unit for detecting the melt temperature of the auxiliary extruder. The control component includes a controller configured to: calculate the melt pressure difference based on the real-time pressure detected by the second detection unit and the preset pressure; calculate the temperature deviation based on the real-time temperature detected by the third detection unit and the preset process temperature; and control the auxiliary extruder screw speed based on the real-time speed of the main screw, the electronic gear ratio, the melt pressure difference, and the temperature deviation detected by the first detection unit.

[0009] Optionally, the auxiliary screw speed of the auxiliary extruder , Where G is the electronic gear ratio, n1(k) is the rotational speed of the main screw at time k, ΔP(k) is the melt pressure difference at time k, ΔT is the temperature deviation, and K p K is the proportionality coefficient. i K is the integral coefficient. d K is the differential coefficient. T This is the temperature compensation coefficient.

[0010] Optionally, the auxiliary screw speed of the auxiliary extruder Where G is the electronic gear ratio, n1(k) is the rotational speed of the main screw at time k, ΔP(k) is the melt pressure difference at time k, ΔT is the temperature deviation, and K p K is the proportionality coefficient. i K is the integral coefficient. d K is the differential coefficient. T K is the temperature compensation coefficient. Ti This is the temperature integral coefficient.

[0011] Optionally, when ΔT≤1, K T =0, when 1 < ΔT ≤ 5, When ΔT > 5, K T =K Tmax K T0 = -0.04 or -0.06, K Tmax = -0.08 or -0.1.

[0012] Alternatively, for PVC cable sheath K Ti =0.002, for PE or XLPE cable sheath K Ti=0.003.

[0013] Optionally, the first detection unit is a photoelectric encoder or a Hall effect speed sensor, the second detection unit is a pressure sensor, and the third detection unit is a temperature sensor.

[0014] Optionally, the second detection unit is installed at the outlet of the flow channel of the auxiliary machine head, and the third detection unit is installed at the position of the auxiliary machine head near the flow channel.

[0015] Optionally, the main extruder includes a main body, a main die head connected to the main body, a main feed hopper connected to the main body, a main screw rotatably disposed within the main body, and a main drive module for driving the main screw to rotate.

[0016] Optionally, the auxiliary extruder includes an auxiliary machine body, an auxiliary machine head connected to the auxiliary machine body, an auxiliary machine feed hopper connected to the auxiliary machine body, an auxiliary machine screw rotatably disposed within the auxiliary machine body, and an auxiliary machine drive module for driving the auxiliary machine screw to rotate, wherein the auxiliary machine drive module includes a frequency converter.

[0017] Optionally, the components of the two-color cable sheath are any one of PVC, PE, and XLPE, and the base layer and the surface layer are the same component.

[0018] The present invention provides an automatic control system for feeding dual-color cable sheaths. Compared with the prior art, its advantages are as follows: It introduces pressure PID compensation and temperature compensation terms respectively, and adopts real-time speed feedback as the basic synchronization logic. When the auxiliary machine's flow channel is slightly blocked or the back pressure increases, the auxiliary machine speed can be quickly reduced to avoid the decrease in flow rate leading to discontinuous or thinning of the color layer. When the temperature is too high, the auxiliary machine speed can be reduced to offset the increase in flow rate caused by the decrease in viscosity, preventing the color layer from thickening. When the temperature is too low, the auxiliary machine speed can be increased to compensate for the decrease in flow rate caused by the increase in viscosity, preventing the color layer from thinning or becoming discontinuous. This ensures a constant feed ratio between the main and auxiliary machines, avoiding fluctuations in color layer thickness due to synchronization mismatch. The detection unit collects speed, pressure, and temperature signals in real time, and the control unit automatically outputs control commands based on the core algorithm to adjust the auxiliary machine speed. Frequent manual parameter adjustments are unnecessary, controlling the color layer thickness fluctuation within ±0.1mm. The incidence of discontinuous color layer defects is reduced by more than 95%, and the product qualification rate is increased to more than 99%, significantly reducing labor costs and improving production efficiency. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0023] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0024] In addition, the term "multiple" should mean two or more.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] like Figure 1As shown, an automatic control system for feeding dual-color cable sheaths includes: a main extruder for extruding the natural-colored base layer of the cable sheath, an auxiliary extruder for extruding the colored surface layer of the cable sheath, a detection component, and a control component. The detection assembly includes a first detection unit for detecting the main screw speed of the main extruder, a second detection unit for detecting the melt pressure of the auxiliary extruder, and a third detection unit for detecting the melt temperature of the auxiliary extruder. The first detection unit is a photoelectric encoder or a Hall effect speed sensor, the second detection unit is a pressure sensor, and the third detection unit is a temperature sensor. The second detection unit is installed at the flow channel outlet of the auxiliary extruder head, and the third detection unit is installed near the flow channel of the auxiliary extruder head.

[0027] The main extruder includes a main body, a main die head connected to the main body, a main feed hopper connected to the main body, a main screw rotatably disposed within the main body, and a main drive module for driving the main screw to rotate.

[0028] The auxiliary extruder includes an auxiliary machine body, an auxiliary machine head connected to the auxiliary machine body, an auxiliary machine feed hopper connected to the auxiliary machine body, an auxiliary machine screw rotatably disposed within the auxiliary machine body, and an auxiliary machine drive module for driving the auxiliary machine screw to rotate, wherein the auxiliary machine drive module includes a frequency converter.

[0029] The control component includes a controller configured to: calculate the melt pressure difference based on the real-time pressure detected by the second detection unit and the preset pressure; calculate the temperature deviation based on the real-time temperature detected by the third detection unit and the preset process temperature; and control the frequency converter to adjust the auxiliary extruder screw speed based on the real-time speed of the main screw, the electronic gear ratio, the melt pressure difference, and the temperature deviation detected by the first detection unit.

[0030] The auxiliary extruder's auxiliary screw speed , Where G is the electronic gear ratio, n1(k) is the rotational speed of the main screw at time k, ΔP(k) is the melt pressure difference at time k, ΔT is the temperature deviation, and K p K is the proportionality coefficient. i K is the integral coefficient. d K is the differential coefficient. TThe temperature compensation coefficient is used. It should be noted that the parameters in the above formula are calculated using only their numerical values ​​and do not contain dimensions. As for the electronic gear ratio G, it is the preset speed of the auxiliary screw / the preset speed of the main screw, which is a fixed value. Based on real-time synchronization with the main machine, a combination of temperature compensation and pressure PID is added. Temperature is compensated slowly, while pressure is used for fast correction, constructing a pressure PID closed-loop + temperature feedforward compensation composite control, thereby achieving more precise control.

[0031] To counteract the gradual thickening or thinning of the color layer caused by prolonged head heating and changes in the workshop environment, a temperature lag integral compensation is introduced based on the above solution. Specifically: The auxiliary extruder's auxiliary screw speed Where G is the electronic gear ratio, n1(k) is the rotational speed of the main screw at time k, ΔP(k) is the melt pressure difference at time k, ΔT is the temperature deviation, and K p K is the proportionality coefficient. i K is the integral coefficient. d K is the differential coefficient. T K is the temperature compensation coefficient. Ti This is the temperature integral coefficient.

[0032] When ΔT≤1, K T =0, when 1 < ΔT ≤ 5, When ΔT > 5, K T =K Tmax K T0 = -0.04 or -0.06, K Tmax = -0.08 or -0.1.

[0033] Alternatively, for PVC cable sheath K Ti =0.002, for PE or XLPE cable sheath K Ti =0.003.

[0034] Example 1: Feeding control for PVC-based two-color cable sheaths This embodiment is for PVC-based two-color cable sheaths (the base layer is PVC, and the colored surface layer is PVC + color masterbatch). The raw material formula by weight parts is as follows: base layer: PVC 100 parts, plasticizer 40 parts, environmentally friendly heat stabilizer 6 parts, kaolin 12 parts, calcium powder 25 parts; colored surface layer: PVC 100 parts, plasticizer 38 parts, environmentally friendly heat stabilizer 5.5 parts, color masterbatch 1.2 parts (yellow). It is suitable for the production of two-color cable sheaths for home decoration and general electrical equipment.

[0035] The main screw speed is set to 25 r / min, and the auxiliary screw speed is set to 8 r / min, resulting in an electronic gear ratio of 0.32. The sampling period is set to 15 ms, and the preset pressure is 14 MPa. p K is 0.6 i K is 0.1 d The value is 0.03. Regarding temperature, the preset process temperature is 160℃, the draw ratio is fixed at 1.1, and the traction line speed is 80m / min. K T0 =-0.04, K Tmax =-0.08, K Ti =0.002.

[0036] The specific control process is as follows: 1. After the system starts, the control unit calls the preset parameters of PVC components, and the main unit starts at the set speed of 25r / min. The speed sensor collects the real-time speed of the main unit in real time. 2. The control unit calculates the base speed of the auxiliary machine based on the core algorithm; 3. Pressure sensors collect the pressure at the auxiliary machine head in real time; 4. Temperature sensors collect the temperature of the auxiliary machine head in real time; 5. Calculate the output speed of the auxiliary machine, and the control unit outputs this command to the auxiliary machine frequency converter to adjust the auxiliary machine speed to ensure that the feed rate of the auxiliary machine matches that of the main machine; 6. When a slight blockage occurs in the flow channel, the pressure PID compensation term increases rapidly, and the auxiliary machine speed is reduced to prevent the color layer from becoming thin and intermittent; when the machine head temperature drops to the preset value, the auxiliary machine speed is increased to replenish the flow.

[0037] The PVC dual-color cable sheath produced in this embodiment has a color layer thickness fluctuation of ≤±0.08mm, no discontinuity, no wavy edges, and a product qualification rate of 99.2%. Compared with the prior art, the color layer defect rate is reduced by 96%.

[0038] Example 2: Feed control for PE or XLPE component dual-color cable sheaths Taking PE as an example: This embodiment is for PE-component dual-color cable sheaths (the base layer is HDPE, and the colored surface layer is LLDPE + color masterbatch). The raw material formula by weight is as follows: base layer: HDPE 100 parts, light stabilizer 0.4 parts, antioxidant 1076 0.15 parts; colored surface layer LLDPE: LLDPE 100 parts, light stabilizer 0.35 parts, antioxidant 1076 0.12 parts, color masterbatch 1.0 part (green). It is suitable for the production of dual-color cable sheaths for buried and bending scenarios.

[0039] The specific parameter settings for the dual-color cable sheath feeding automatic control system in this embodiment are as follows: The main screw speed is set to 22 r / min, and the auxiliary screw speed is set to 7 r / min, resulting in an electronic gear ratio of 0.318. The sampling period is set to 12 ms, and the preset pressure is 18 MPa. p K is 0.8 i K is 0.12. d The value is 0.04. Regarding temperature, the preset process temperature is 150℃, the draw ratio is fixed at 1.15, the traction line speed is 100m / min, and K... T0 =-0.06, K Tmax =-0.1,K Ti =0.003.

[0040] The control process in this embodiment is basically the same as that in embodiment 1, with the key difference being: 1. The viscosity-temperature coefficient of PE material is approximately 0.018~0.028, making it more sensitive to temperature; therefore, K is set as... T0 = -0.06, resulting in faster temperature compensation response; 2. PE requires higher melt pressure, therefore K is set. p The value is 0.8 to ensure rapid correction of pressure fluctuations.

[0041] The PE dual-color cable sheath produced in this embodiment has a color layer thickness fluctuation of ≤±0.07mm, no discontinuity, no color bleeding, and a product qualification rate of 99.5%, which is suitable for the environmental stress cracking resistance requirements of buried scenarios.

[0042] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An automatic control system for feeding dual-color cable sheaths, characterized in that, include: A main extruder for extruding the natural base layer of cable sheath, an auxiliary extruder for extruding the colored surface layer of cable sheath, a detection assembly, and a control assembly; The detection assembly includes a first detection unit for detecting the main screw speed of the main extruder, a second detection unit for detecting the melt pressure of the auxiliary extruder, and a third detection unit for detecting the melt temperature of the auxiliary extruder. The control component includes a controller configured to: calculate the melt pressure difference based on the real-time pressure detected by the second detection unit and the preset pressure; calculate the temperature deviation based on the real-time temperature detected by the third detection unit and the preset process temperature; and control the auxiliary screw speed of the auxiliary extruder based on the real-time speed of the main screw, the electronic gear ratio, the melt pressure difference, and the temperature deviation detected by the first detection unit, wherein the electronic gear ratio is the preset speed of the auxiliary screw / the preset speed of the main screw.

2. The automatic control system for feeding dual-color cable sheaths as described in claim 1, characterized in that: The auxiliary extruder's auxiliary screw speed , Where G is the electronic gear ratio, n1(k) is the rotational speed of the main screw at time k, ΔP(k) is the melt pressure difference at time k, ΔT is the temperature deviation, and K p K is the proportionality coefficient. i K is the integral coefficient. d K is the differential coefficient. T This is the temperature compensation coefficient.

3. The automatic control system for feeding dual-color cable sheaths as described in claim 1, characterized in that: The auxiliary extruder's auxiliary screw speed Where G is the electronic gear ratio, n1(k) is the rotational speed of the main screw at time k, ΔP(k) is the melt pressure difference at time k, ΔT is the temperature deviation, and K p K is the proportionality coefficient. i K is the integral coefficient. d K is the differential coefficient. T K is the temperature compensation coefficient. Ti This is the temperature integral coefficient.

4. An automatic control system for feeding dual-color cable sheaths as described in claim 2 or 3, characterized in that, When ΔT≤1, K T =0, when 1 < ΔT ≤ 5, When ΔT > 5, K T =K Tmax K T0 = -0.04 or -0.06, K Tmax = -0.08 or -0.

1.

5. The automatic control system for feeding dual-color cable sheaths as described in claim 3, characterized in that: For PVC cable sheath K Ti =0.002, for PE or XLPE cable sheath K Ti =0.

003.

6. The automatic control system for feeding dual-color cable sheaths as described in claim 1, characterized in that: The first detection unit is a photoelectric encoder or a Hall effect speed sensor, the second detection unit is a pressure sensor, and the third detection unit is a temperature sensor.

7. The automatic control system for feeding dual-color cable sheaths as described in claim 6, characterized in that: The second detection unit is installed at the outlet of the flow channel of the auxiliary machine head, and the third detection unit is installed at the position of the auxiliary machine head near the flow channel.

8. The automatic control system for feeding dual-color cable sheaths as described in claim 1, characterized in that: The main extruder includes a main body, a main die head connected to the main body, a main feed hopper connected to the main body, a main screw rotatably disposed within the main body, and a main drive module for driving the main screw to rotate.

9. The automatic control system for feeding dual-color cable sheaths as described in claim 1, characterized in that: The auxiliary extruder includes an auxiliary machine body, an auxiliary machine head connected to the auxiliary machine body, an auxiliary machine feed hopper connected to the auxiliary machine body, an auxiliary machine screw rotatably disposed within the auxiliary machine body, and an auxiliary machine drive module for driving the auxiliary machine screw to rotate, wherein the auxiliary machine drive module includes a frequency converter.

10. The automatic control system for feeding dual-color cable sheaths as described in claim 1, characterized in that: The components of the dual-color cable sheath are any one of PVC, PE, and XLPE, and the base layer and the surface layer are made of the same component.

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