Constant temperature control method based on temperature and speed regulation

Abstract

The constant temperature control method based on temperature and speed regulation described in the present invention proposes a control means to maintain the temperature fluctuation and overshoot of the dyeing liquid in the constant temperature process of the dyeing machine, so as to improve the intelligence of the constant temperature process control, effectively and automatically detect and accurately control the temperature of the dyeing process, thereby achieving the design purpose of stable heat preservation and reaching the preset temperature conditions of the dyeing liquid in the process, and significantly improving the dyeing effect and product quality. The constant temperature control method based on temperature and speed regulation is that in the printing and dyeing process, according to the requirements of the printing and dyeing process for temperature and temperature speed indicators, after determining the insulation temperature Th of the dyeing liquid, the initial temperature speed V0 is determined according to the size of the temperature difference ΔT; the controller compares the real-time monitored temperature with the process temperature, and indirectly realizes the temperature control of the dyeing liquid in the constant temperature process by adjusting the size of the opening of the pneumatic film regulating valve. The constant temperature control method of the present invention has good control effect and high control accuracy, and effectively overcomes the shortcomings of conventional control methods.

Description

Technical Field

[0001] The invention proposes a high-precision control method for a constant temperature process in a dyeing process of an overflow dyeing machine, and belongs to the technical field of printing and dyeing equipment. Background Art

[0002] At present, overflow dyeing equipment is widely used in the domestic fabric printing and dyeing industry for pre- and post-treatment and dyeing of various pure cotton, pure polyester, polyester-cotton, spandex and other knitted fabrics. It is especially suitable for dyeing high value-added new synthetic fibers and ultra-fine fibers. It can also be used for fabric scouring, bleaching, pre-shrinking, alkali reduction and other processing.

[0003] Overflow dyeing machine is a dyeing equipment widely used in existing printing and dyeing factories. Its working principle is that the dye liquid is pumped out from the bottom of the dye tank by the main pump, sent to the heat exchanger for heating, and then enters the overflow tank at the front end of the dye tank. Two or more downward overflow pipes are installed in parallel in the overflow tank. The fabric is driven by the active cloth guide roller and the overflow of the dye liquid for circulation. Fabric printing and dyeing is a complex process, which is affected by multiple factors, and multiple factors are coupled and act together. The dyeing quality is difficult to control. There are many main factors affecting the dyeing quality of the overflow dyeing machine, such as dye liquid and addition method, dyeing temperature, salt and alkali agent type, dosage and addition method, dyeing time, dye liquor bath ratio, etc. The dyeing process has very strict requirements on temperature control. The heating, insulation and cooling of the dye liquid must meet the process requirements, otherwise color difference, cylinder difference, uneven coloring and other inferior products will be produced.

[0004] When dyeing, the overflow dyeing machine of the prior art needs to increase the temperature of the dye to increase the activity of the dye, and maintain it within a certain temperature range, that is, it needs to undergo a constant temperature process, so as to improve the dyeing efficiency. Due to the differences in different environments and machines, the actual temperature curve of the dyeing process is quite different from the ideal setting curve, which will accordingly lead to related dyeing quality problems, resulting in poor dyeing efficiency and high production costs, and cannot meet the needs of modern production processes and efficient mass production. In addition, due to the low temperature control level, a large amount of water resources will be wasted, the environmental protection cost investment will be increased, and satisfactory printing and dyeing quality control effects will not be obtained.

[0005] In view of this, this patent application is proposed. Summary of the invention

[0006] The constant temperature control method based on temperature and speed regulation described in the present invention aims to solve the problems existing in the prior art and propose a control means for maintaining the temperature fluctuation and overshoot of the dye liquid in the constant temperature process of the dyeing machine, so as to improve the intelligent control of the constant temperature process, effectively and automatically detect and accurately control the temperature of the dyeing process, thereby achieving the design purpose of stable heat preservation and reaching the preset dye liquid temperature conditions of the process, and significantly improving the dyeing effect and product quality.

[0007] To achieve the above design purpose, the constant temperature control method based on temperature and speed regulation is that in the printing and dyeing process, according to the requirements of the printing and dyeing process for temperature and temperature speed indicators, after determining the insulation temperature Th of the dye solution, the initial temperature speed V0 is determined according to the size of the temperature difference ΔT;

[0008] The controller compares the real-time monitored temperature with the process temperature, and indirectly controls the temperature of the dye solution during the constant temperature process by adjusting the opening of the pneumatic membrane regulating valve.

[0009] Assume that the temperature difference ΔT at time t0 is TE. According to the temperature difference ΔT, the set value of the temperature speed can be set in stages to achieve continuous stepless control, then:

[0010]

[0011] Where V set is the set value of temperature speed, unit: ℃ / min;

[0012] V0 is the initial setting value of the temperature speed, unit: ℃ / min;

[0013] ΔT is the temperature difference between the insulation temperature Th and the real-time temperature Ts, unit: °C;

[0014] TE is a constant. When ΔT approaches 0, V set tends to 0;

[0015] ω is the attenuation coefficient;

[0016] t is time, unit: min.

[0017] 1. The constant temperature control method based on temperature and speed regulation according to claim 1 is characterized in that:

[0018]

[0019] Where, V is the real-time temperature rate, unit: ℃ / min;

[0020] Since the sampling period is TS, k is the kth sampling, the above formula (4) is discretized to obtain:

[0021]

[0022] The control law of the temperature and speed controller adopts the incremental PID formula. At time k, the discrete formula of the controller temperature and speed deviation Ve is as follows:

[0023] Ve(k)=Vset(k)-V(k) (6)

[0024]

[0025] u(k)=u(k-1)+Δu(k)

[0026] or (11)

[0027] u(k)=u(0)+Δu(k)

[0028] Formula (10) and formula (11) are iterative incremental temperature rate control formulas.

[0029] Furthermore, when the temperature rate setting Vset is less than 0.2℃ / min,

[0030] K P ′=K P / α (12)

[0031] T I ′=T I / β (13)

[0032] In the formula, α is the reduced magnification;

[0033] β is the multiple of increasing the integral effect;

[0034] Substituting the above formula (12) and formula (13) into formula (10) respectively, we can obtain:

[0035]

[0036] The PID parameters are automatically adjusted according to the temperature and speed.

[0037] As described above, the constant temperature control method based on temperature and speed regulation described in this application has the following advantages:

[0038] 1. The present application can meet the requirements of the dyeing industry process for temperature control accuracy and stability, realize high-precision control through temperature and speed adjustment, can achieve the characteristics of small overshoot, good intelligence and controllability, and has the performance of rapid response, good tracking performance and real-time elimination of dye solution temperature deviation, which significantly improves the uniformity and stability of dyeing quality.

[0039] 2. The present application can effectively maintain the temperature conditions of the dye solution according to the process requirements, which not only improves the dyeing effect and ensures the product quality, but also significantly improves the production efficiency and reduces the production cost, while avoiding the waste of water resources in the dyeing process and reducing the pressure on the environmental protection.

[0040] 3. This application is an intelligent method that integrates dyeing technology, automatic control, mechatronics, soft measurement technology, computer monitoring and other technologies, thus laying a solid foundation for the digitalization, intelligence and information development of overflow dyeing industry technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the process and system structure of an overflow dyeing machine to which the control method described in this application is applied;

[0042] Figure 2 It is a heating and insulation curve diagram;

[0043] Figure 3 It is a temperature setting curve graph.

[0044] Figure 4 It is the principle diagram of constant temperature real-time control; DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0046] Example 1, the present application proposes a constant temperature control method based on temperature and speed regulation, based on Figure 1 The overflow dyeing machine process and system structure shown in the figure, in order to meet the requirements of the dyeing process for temperature control accuracy and stability, the overflow dyeing machine includes a dyeing vat, a main pump, a heat exchanger, a nozzle, a temperature sensor, a control system, a pneumatic diaphragm regulating valve, etc. In the printing and dyeing process, the dye liquid in the dyeing vat needs to be heated, kept warm, and cooled. The heat exchange medium for heating and keeping warm is steam, and the heat exchange medium for cooling is cold water. The heat exchange is achieved through the heat exchanger, that is, only one medium can flow through the heat exchanger within a certain period of time, that is, the heating and keeping warm process cannot cool down, and the cooling only comes from the heat dissipation of the equipment itself.

[0047] Based on the principle of gas-liquid overflow temperature and speed regulation, during the printing and dyeing process, the main pump is used as the power to send the dye liquid at the bottom of the dyeing tank to the heat exchanger for heating or cooling, so that the temperature of the dye liquid reaches the temperature required by the process, and then the dye liquid is sprayed on the fabric by the nozzle to achieve the purpose of dyeing. At the same time, the dyed fabric moves downward with the liquid flow, and the dye liquid naturally falls to the bottom of the dyeing tank, and works in this cycle. When the dye liquid is heated, the heat exchanger passes steam, and when it is cooled, the heat exchanger passes cold water. According to the requirements of the printing and dyeing process for temperature and temperature speed indicators, the controller compares the real-time monitored temperature with the process temperature; by measuring the dye liquid temperature, the deviation from the set temperature is calculated, and the deviation from the actual temperature speed is calculated in real time based on the temperature deviation. The size of the opening of the pneumatic diaphragm regulating valve is controlled to indirectly realize the control of the dye liquid temperature and temperature speed, so as to achieve the purpose of controlling the temperature and temperature speed.

[0048] Since the system temperature of the overflow dyeing machine in the prior art is over-temperature and uncontrollable, this application proposes a method of segmented temperature speed control. That is, the state control of the temperature is to achieve the purpose of controlling the temperature, and the process temperature expected curve is as follows Figure 2 shown.

[0049] Specifically, the temperature speed setting value V is determined according to the temperature difference ΔT between the real-time dye solution temperature Ts and the insulation temperature Th. set The controller makes the temperature velocity V follow V in real time. set In order to achieve the purpose of controlling temperature.

[0050] Assume that the temperature difference ΔT at time t0 is TE. According to the temperature difference ΔT, the set value of the temperature speed can be set in stages to achieve continuous stepless control, then:

[0051]

[0052] Where V set is the set value of temperature speed, unit: ℃ / min;

[0053] V0 is the initial setting value of the temperature speed, unit: ℃ / min;

[0054] ΔT is the temperature difference between the insulation temperature Th and the real-time temperature Ts, unit: °C;

[0055] TE is a constant. When ΔT approaches 0, V set tends to 0;

[0056] ω is the attenuation coefficient;

[0057] t is time, unit: min.

[0058] According to the above formula (1), the temperature speed setting value V set The curve is as Figure 3 shown.

[0059] Assume that the deceleration process lasts tn-t0=m minutes, the sampling period is TS, and the total number of sampling times is n=m / ts. That is to say, after n sampling times, ΔT≈0 and Vset≈0. Since ΔT=Th-Ts, the sign of Vset is the same as ΔT. Discretize the changing part of formula (1) to obtain:

[0060] V set =sgn(ΔT)·V0·e -ω·i·TS (i=0,1,2,…,n) (2)

[0061] In the formula, m is the adjustment process time, unit: min;

[0062] n is the number of adjustments within the adjustment process time;

[0063] sgn(ΔT) takes the sign of ΔT;

[0064] TS is the sampling period, unit: min;

[0065] i is the i-th sampling (i=0,1,2,3,…,n);

[0066] According to the test results, when i=n, ​​Vset=0.05℃ / min can meet the temperature control requirements. Substituting this parameter into the above formula (2) to obtain:

[0067]

[0068] As analyzed and deduced above, when the temperature is uncontrollable, the follow-up control system theory and conventional PID algorithm are used to implement the following temperature control method based on temperature and speed control.

[0069] The constant temperature control method based on temperature and speed regulation described in the present application is applied to various overflow dyeing machines with the same process. During the printing and dyeing process, according to the requirements of the printing and dyeing process for temperature and temperature speed indicators, after determining the insulation temperature Th of the dye solution, the initial temperature speed V0 can be determined according to the size of the temperature difference ΔT. The controller compares the real-time monitored temperature with the process temperature, and indirectly realizes the temperature control of the dye solution during the constant temperature process by adjusting the size of the opening of the pneumatic diaphragm regulating valve.

[0070] like Figure 4 As shown, according to the servo control system theory, the real-time dye liquid temperature Ts is measured by the temperature sensor installed between the dye liquid outlet of the heat exchanger and the dye liquid inlet of the main cylinder. The relationship between the real-time dye liquid temperature Ts and the temperature velocity V is:

[0071]

[0072] Where, V is the real-time temperature rate, unit: ℃ / min;

[0073] Since the sampling period is TS, k is the kth sampling, the above formula (4) is discretized to obtain:

[0074]

[0075] The control law of the temperature and speed controller adopts the incremental PID formula. At time k, the discrete formula of the controller temperature and speed deviation Ve is as follows:

[0076] Ve(k)=Vset(k)-V(k) (6)

[0077] At time k, the PID position discrete formula is:

[0078]

[0079] Where, u is the controller output value;

[0080] K P is the controller magnification;

[0081] T Iis the controller integration time, in min;

[0082] T D is the controller differential time, in min;

[0083] TS is the controller differential time, in min;

[0084] According to the above formula (7), at time k-1, the PID position discrete formula is:

[0085]

[0086] Assuming the temperature speed control increment is Δu, we have:

[0087] Δu(k)=u(k)-u(k-1) (9)

[0088] Where Δu is the controller output increment;

[0089] Substituting equations (7) and (8) into equation (9) at time k, we have

[0090]

[0091] The above formula (10) is the differential PID increment formula.

[0092] Formula (9) can be transformed into:

[0093] u(k)=u(k-1)+Δu(k)

[0094] or (11)

[0095] u(k)=u(0)+Δu(k)

[0096] The above formulas (10) and (11) are iterative incremental temperature rate control formulas.

[0097] In order to better eliminate temperature deviation and enhance system stability, when the temperature speed setting Vset is less than 0.2℃ / min, reduce the proportional effect and increase the integral effect, that is,

[0098] K P ′=K P / α (12)

[0099] T I ′=T I / β (13)

[0100] In the formula, α is the reduced magnification;

[0101] β is the multiple of increasing the integral effect;

[0102] Substituting the above formula (12) and formula (13) into formula (10) respectively, we can obtain:

[0103]

[0104] As mentioned above, the self-tuning of PID parameters can be realized according to the size of the temperature speed, thereby ensuring the control accuracy of the temperature speed and indirectly realizing the precise control of the dye solution temperature during the constant temperature process.

[0105] As described above, similar technical solutions can be derived from the solutions given in the drawings and descriptions. However, any solution content that does not deviate from the structure of the present invention still belongs to the scope of rights of the technical solution of the present invention.

Claims

1. A constant temperature control method based on temperature and speed regulation, characterized in that: In the printing and dyeing process, according to the requirements of the printing and dyeing process for temperature and temperature speed indicators, after determining the insulation temperature Th of the dye solution, the initial temperature speed V0 is determined according to the size of the temperature difference ΔT; The controller compares the real-time monitored temperature with the process temperature, and indirectly controls the temperature of the dye solution during the constant temperature process by adjusting the opening of the pneumatic membrane regulating valve. Specifically, the temperature speed setting value V is determined according to the temperature difference ΔT between the real-time dye solution temperature Ts and the insulation temperature Th. set The controller makes the temperature velocity V follow V in real time. set To achieve the purpose of controlling temperature; Assume that the temperature difference ΔT at time t0 is TE. According to the temperature difference ΔT, the set value of the temperature speed can be set in stages to achieve continuous stepless control, then: Where V set is the set value of temperature speed, unit: ℃ / min; V0 is the initial setting value of the temperature speed, unit: ℃ / min; ΔT is the temperature difference between the insulation temperature Th and the real-time temperature Ts, unit: °C; TE is a constant. When ΔT approaches 0, V set tends to 0; ω is the attenuation coefficient; t is time, unit: min.

2. The constant temperature control method based on temperature and speed regulation according to claim 1, characterized in that: Where, V is the real-time temperature rate, unit: ℃ / min; Since the sampling period is TS, k is the kth sampling, the above formula (4) is discretized to obtain: The control law of the temperature and speed controller adopts the incremental PID formula. At time k, the discrete formula of the controller temperature and speed deviation Ve is as follows: Ve(k)=Vset(k)-V(k) (6) Formula (10) and Formula (11) are iterative incremental temperature and speed control formulas.

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