Temperature control system of weighing type paraffin continuous forming machine

Abstract

The invention belongs to the technical field of paraffin forming machines, and particularly relates to a weighing type paraffin continuous forming machine temperature control system which comprises a machine head part and a cold chamber part, the machine head part is installed at the front end of the cold chamber part, and the machine head part comprises a machine head frame, a driving mechanism, a heat exchange system, a paraffin injection system and a paraffin unloading mechanism. The automatic wax injection machine has the advantages that the influence of liquid wax density and temperature on wax injection precision is solved, the principle is simple, liquid wax enters a wax injector through a weighing control valve after heat exchange according to the production process requirement, and the wax injection accuracy is improved. The process is not influenced by external factors, and high-precision continuous production can be realized through dynamic control of the system.

Description

Technical Field

[0001] The invention belongs to the technical field of paraffin wax molding machines, and in particular relates to a temperature control system of a weighing type paraffin wax continuous molding machine. Background Art

[0002] The traditional volume measurement technology is affected by the density and temperature of liquid wax. The wax injection accuracy is difficult to meet the actual production requirements and can only be maintained within the range of ±8‰. In order to meet the needs of automatic packaging production, the weight of each bag (10 pieces / bag) can only be increased by manual weighing, resulting in unnecessary loss of paraffin and increased production costs. This wax injection technology can no longer meet the requirements of modern production. The control technology with stable operation, easy maintenance and high wax injection accuracy is increasingly recognized by users and the market. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a weighing type paraffin wax continuous molding machine temperature control system to solve the problems of unnecessary loss of paraffin wax and increased production costs in the prior art.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] It includes a head part and a cold chamber part, wherein the head part is installed at the front end of the cold chamber part, and the head part includes a head frame, a driving mechanism, a heat exchange system, a wax injection system and a wax unloading mechanism, wherein the driving mechanism is installed inside the head frame, the heat exchange system is connected to the wax injection system, and the wax unloading mechanism is installed at the rear side of the wax injection system;

[0006] The cold chamber part is connected to the head part through a conveyor. The cold chamber part includes a cold chamber, a cold chamber frame, a translation mechanism, a tensioning mechanism and a cooling mechanism. The cold chamber is installed inside the cold chamber frame. The translation mechanism and the tensioning mechanism are relatively installed on both sides of the cold chamber. The cooling mechanism is installed at the lower part of the cold chamber. The cold chamber frame is provided with upper and lower groups of interlayers, and the interlayers are evenly distributed.

[0007] Furthermore, the wax injection system includes a bracket, a connector, a wax injector, a spring and a wax storage tube. The bracket is connected to the wax injector through the connector. A group of weighing sensors are provided on both sides of the connector. The spring is provided at the bottom of the wax injector, and a sealing device is provided at the bottom of the spring. A spoiler is installed outside the sealing device. A weighing control valve is also provided under the wax injector. The wax storage tube is conductively connected to the wax injector, and a wax pump is provided between the wax storage tube and the wax injector.

[0008] Furthermore, the weighing control valve includes a valve body bracket, a multi-position actuator, a weighing linker and a valve body, the valve body bracket is arranged at the upper end of the valve body, the multi-position actuator is installed inside the valve body bracket, the weighing linker connects the multi-position actuator and the valve body, a fluid inlet is provided on one side of the valve body, a fluid outlet is provided at the lower end of the valve body, and a spoiler is provided at the fluid outlet.

[0009] Furthermore, the wax injection system also includes a wax injection platform, on which at least two groups of working lines are installed, each group of working lines is provided with at least three groups of wax injection systems, and the two groups of working lines inject wax alternately.

[0010] Furthermore, the cooling mechanism includes a cooling motor, an evaporator, a diffuser and a cooling fan, the cooling motor is connected to the cooling fan, the cooling fan blows the cooling energy provided by the evaporator into the lower layer through the upper layer of the cold chamber frame and returns to the evaporator, the diffuser diffuses the air volume of the cooling fan to the upper layer of the cold chamber frame, the cold chamber frame is provided with a plurality of layers of air guide plates, the air guide plates proportionally guide the diffuser air volume into the cold chamber frame, the cold chamber frame is also provided with an upper partition and a lower partition, the upper partition is placed between the upper layer and the lower layer of the cold chamber frame, and the lower partition is placed at the bottom layer of the cold chamber frame.

[0011] Furthermore, the driving mechanism includes a main motor, a main motor sprocket, and a transmission sprocket. The main motor is connected to the main motor sprocket, the main motor sprocket is connected to the transmission sprocket, the upper part of the transmission sprocket is also connected to a driving sprocket, the driving sprocket is connected to a plurality of flip sprockets, a tensioning sprocket is provided at the far end of the flip sprocket, and a translation sprocket is provided between the tensioning sprocket and the flip sprocket.

[0012] Furthermore, the heat exchange system includes a wax and water heat exchanger, a water and water heat exchanger, a water circulation pump, a wax regulating valve, a water regulating valve, a steam regulating valve, and a wax circulation pump. The wax and water heat exchanger is conductively connected to the wax injection system and the water and water heat exchanger, the water circulation pump is conductively connected to the wax and water heat exchanger, the wax regulating valve is conductively connected to the wax injection system, the water regulating valve is conductively connected to the water circulation pump, the steam regulating valve is arranged directly below the water circulation pump and the water regulating valve, and the wax circulation pump is conductively connected to the wax injection system.

[0013] Furthermore, the cold room wall and upper cover are formed by 100mm thick flame-retardant polyurethane foaming, each foaming board is 900mm wide, has concave and convex surfaces, and is installed in a socket-type manner.

[0014] Furthermore, the conveyor is composed of a driving roller, a driven roller, a supporting roller, a conveyor belt reduction motor, etc. and a wax tray.

[0015] Furthermore, the function of the interlayer is to evenly distribute the wax tray group into 14 layers and transmit the wax tray group to the translation and tensioning device.

[0016] Furthermore, the wax unloading mechanism is composed of a turning device, an upper top wheel, a lower top wheel, a canvas, a wax receiving plate, and a detection device, and its function is to turn over and demould the wax tray group coming out of the cold room.

[0017] Furthermore, the heat exchange system adjusts the output through a PID controller, and the principle formula of the PID controller adjusting the output is as follows:

[0018]

[0019] Among them, M(t) is the loop output as a time function;

[0020] Kc loop gain;

[0021] E loop deviation;

[0022] Minitial loop output initialization.

[0023] Furthermore, in order for the system to process this control formula, the continuous formula must be discretized into a periodic sampling deviation formula before it can be used to calculate the output value. The processing formula is as follows:

[0024]

[0025] in:

[0026] Mn is the calculated value of the loop output at sampling time n;

[0027] Kc loop gain;

[0028] En loop deviation value at sampling time n;

[0029] E(n-1) the previous value of the loop deviation;

[0030] The proportionality constant of the integral term Ki;

[0031] The initial value of the Minitial loop output;

[0032] Kd is the proportionality constant of the differential term.

[0033] Furthermore, the continuous formula must be discretized into a periodic sampling deviation formula, and the processing formula is as follows:

[0034]

[0035] in:

[0036] Mn is the calculated value of the loop output at sampling time n;

[0037] Kc is the loop gain;

[0038] En is the loop deviation value at sampling time n;

[0039] E(n-1) is the previous value of the loop deviation;

[0040] Ki is the proportional constant of the integral term;

[0041] Minitial is the initial value of the loop output;

[0042] Kd is the proportionality constant of the differential term.

[0043] Furthermore, the simplified formula of the equation for calculating the sampling time is:

[0044] in:

[0045] Mn loop output calculation value at sampling time n

[0046] MPn loop output proportional term value at sampling time n

[0047] The value of the loop output integral term at sampling time n

[0048] MDn is the value of the loop output differential term at sampling time n

[0049] Furthermore, the proportional term of the PID controller output adjustment principle formula is:

[0050] MP n =K C (SP n -PV n );

[0051] Among them, MP n is the value of the proportional term at the nth sampling moment;

[0052] Kc is the gain;

[0053] SP n is the given value at the nth sampling moment;

[0054] PV n PV n The process variable value.

[0055] Furthermore, the integral term of the PID controller output adjustment principle formula is:

[0056] MI n =K C *TS / TI*(SP n -PV n )+MX;

[0057] Among them, MI n is the integral term value at the nth sampling moment;

[0058] TS is the sampling time interval;

[0059] TI is the integration time;

[0060] SP n is the given value at the nth sampling moment;

[0061] PV n PV n The process variable value;

[0062] MX is the integrated value at the n-1th sampling moment.

[0063] Furthermore, the differential term of the PID controller output adjustment principle formula is: MD n =K C *T D / *((SP n -PV n )·(SP n-1 -PV n-1 )).

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] This technology can solve the influence of liquid wax density and temperature on wax injection accuracy, and the principle is simple, that is, the liquid wax is heat exchanged according to the production process requirements, enters the wax injector through the weighing control valve, and is injected into the wax tray after reaching the weight requirement. The process is not affected by external factors, and high-precision continuous production can be achieved through dynamic control of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a structural schematic diagram of an embodiment of a temperature control system of a weighing type paraffin wax continuous molding machine of the present invention;

[0067] Figure 2 The partial structure of the embodiment of the temperature control system of the weighing type paraffin continuous molding machine of the present invention is shown in FIG. Figure 1 ;

[0068] Figure 3 The partial structure of the embodiment of the temperature control system of the weighing type paraffin continuous molding machine of the present invention is shown in FIG. Figure 2 ;

[0069] Figure 4 The partial structure of the embodiment of the temperature control system of the weighing type paraffin continuous molding machine of the present invention is shown in FIG. Figure 3 ;

[0070] Figure 5 The partial structure of the embodiment of the temperature control system of the weighing type paraffin continuous molding machine of the present invention is shown in FIG. Figure 4 ;

[0071] Figure 6 The partial structure of the embodiment of the temperature control system of the weighing type paraffin continuous molding machine of the present invention is shown in FIG. Figure 5 ;

[0072] Figure 7 The partial structure of the embodiment of the temperature control system of the weighing type paraffin continuous molding machine of the present invention is shown in FIG. Figure 6 ;

[0073] Figure 8 The partial structure of the embodiment of the temperature control system of the weighing type paraffin continuous molding machine of the present invention is shown in FIG. Figure 7 ;

[0074] Fig. 9 This is the schematic diagram of the temperature control system;

[0075] The reference numerals in the drawings of the specification include:

[0076] Head part 1, head frame 11,

[0077] Driving mechanism 12, main motor 121, main motor sprocket 122, transmission sprocket 123, driving sprocket 124, flip sprocket 125, tensioning sprocket 126;

[0078] Heat exchange system 13, wax-water heat exchanger 131, water-water heat exchanger 132, water circulation pump 133, wax regulating valve 134, water regulating valve 135, steam regulating valve 136, wax circulation pump 137;

[0079] Wax injection system 14, bracket 140, connector 141, wax injector 142, spring 143, weighing sensor 144, sealing device 145, wax storage tube 1400, spoiler 146;

[0080] Wax unloading mechanism 15;

[0081] Cold room part 2, cold room 21, cold room frame 22, air guide plate 221, upper partition 222, lower partition 223, translation mechanism 23

[0082] Conveyor 3;

[0083] Cooling mechanism 4, cooling motor 41, evaporator 42, diffuser 43 and cooling fan 44;

[0084] Weighing control valve 5 , valve body bracket 51 , multi-position actuator 52 , weighing linker 53 , valve body 54 , fluid inlet 540 , fluid outlet 541 , and spoiler 542 . DETAILED DESCRIPTION

[0085] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0086] It should be noted that the same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0087] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0088] In the description of the present invention, unless otherwise clearly specified and limited, if the term "connection" or the like appears to indicate the connection relationship between components, the term should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0089] Example

[0090] like Figure 1-Figure 9 As shown, the machine head portion 1 and the cold chamber portion 2 are included. The machine head portion 1 is installed at the front end of the cold chamber portion 2. The machine head portion 1 includes a machine head frame 11, a driving mechanism 12, a heat exchange system 13, a wax injection system 14 and a wax unloading mechanism 15. The driving mechanism 12 is installed inside the machine head frame 11, the heat exchange system 13 is connected to the wax injection system 14, and the wax unloading mechanism 15 is installed at the rear side of the wax injection system 14.

[0091] The cold chamber part 2 is connected to the head part 1 through a conveyor 3. The cold chamber part 2 includes a cold chamber 21, a cold chamber frame 22, a translation mechanism 23, a tensioning mechanism 24 and a cooling mechanism 4. The cold chamber 21 is installed inside the cold chamber frame 22. The translation mechanism 23 and the tensioning mechanism 24 are relatively installed on both sides of the cold chamber 21. The cooling mechanism 4 is installed at the lower part of the cold chamber 21. The cold chamber frame 22 is provided with upper and lower groups of interlayers, and the interlayers are evenly distributed.

[0092] The translation mechanism 23 distributes the power output by the driving mechanism 12 to each layer, and smoothly moves the wax tray group to the upper track.

[0093] The chain between the tensioning mechanism 24 and the translation mechanism 23 is always in a tensioned state. At the same time, the tension value of the chain is detected by the tension sensor, and the wax tray group is smoothly moved to the upper track. The design and manufacturing technology of the tensioning device and the chain on the same center line is adopted to effectively eliminate the influence of lateral stress. The tension sensor can provide real-time online feedback on the actual chain tension. Through the control system, fault prediction and alarm can be realized to improve the reliability of equipment operation.

[0094] The cold room frame 22 evenly distributes the wax tray group in 14 layers and transmits the wax tray group to the translation and tensioning device, which is mainly composed of channel steel, angle steel, and rails. The connection points are fastened with bolts. The liquid wax comes from the process pipeline with a temperature of 58℃-86℃;

[0095] After the wax-water heat exchange and water-water heat exchange, the wax liquid is cooled. After the temperature of the wax liquid drops to 70℃, it enters the wax injector through the weighing control valve; the control system injects the liquid wax into the wax tray group of the paraffin continuous molding machine according to the weight of 5KG through dynamic weighing; the wax tray group is driven by the main motor and brought into the cold room by the chain; the temperature of the cold room is controlled at 5℃-7℃ by the evaporator, and the liquid wax in the cold room gradually solidifies; after the wax tray group in the cold room circulates on the track for one week, the liquid wax solidifies and forms a wax plate; the wax tray group reaches the wax unloading position, and the wax plate is separated from the wax tray through the wax unloading device and unloaded onto the conveyor belt. The conveyor belt transports the wax blocks to the packaging line for packaging.

[0096] The wax injection system 14 includes a bracket 140, a connector 141, a wax injector 142, a spring 143 and a wax storage tube 1400. The bracket 140 is connected to the wax injector 142 through the connector 141. A group of weighing sensors 144 are respectively provided on both sides of the connector 141. The spring 143 is provided at the bottom of the wax injector 142, and a sealing device 145 is provided at the bottom of the spring 143. A spoiler 146 is installed outside the sealing device 145. A weighing control valve 5 is also provided below the wax injector 142. The wax storage tube 1400 is connected to the wax injector 142, and the wax storage tube 1400 and the wax injector 142 are provided with a wax pump. During weighing measurement, the wax storage tube 1400 is separated from the wax injector 142; after weighing, the wax storage tube 1400 remains connected to the wax injector 142, and the liquid wax in the weighing wax storage tube 1400 is injected into the wax tray. When weighing again, it returns to the separated state, and the action is circulated in this way. A liquid flow stabilizing device is also provided inside the wax injector 142, and the liquid flow stabilizing device can minimize the impact interference of the liquid on the weighing sensor when it is dynamic.

[0097] The weighing control valve 5 includes a valve body bracket 51, a multi-position actuator 52, a weighing linker 53 and a valve body 54. The valve body bracket 51 is arranged at the upper end of the valve body 54, the multi-position actuator 52 is installed inside the valve body bracket 51, the weighing linker 53 connects the multi-position actuator 52 and the valve body 54, a fluid inlet 540 is arranged on one side of the valve body 54, a fluid outlet 541 is arranged at the lower end of the valve body 54, and a spoiler 542 is arranged at the fluid outlet 541. The weighing control valve 5 adopts imported components such as Festo and SMC to improve the reliability of the valve to ensure the repeatability of the valve mechanical action. The spoiler 542 reduces the impact of the liquid wax on the weighing tank and the interference of the weighing system when the liquid wax passes through the weighing control valve to the wax injector.

[0098] The wax injection system 14 further comprises a wax injection platform 147 , on which at least two groups of working lines are installed, each group of working lines is provided with at least three groups of wax injection systems, and the two groups of working lines inject wax alternately.

[0099] The cooling mechanism 4 includes a cooling motor 41, an evaporator 42, a diffuser 43 and a cooling fan 44. The cooling motor 41 is connected to the cooling fan 44. The cooling fan 44 blows the cold provided by the evaporator 42 into the lower layer through the upper layer of the cold chamber frame 22 and returns to the evaporator 42. The diffuser 43 diffuses the air volume of the cooling fan 44 to the upper layer of the cold chamber frame 22. The cold chamber frame 22 is provided with a plurality of layers of air guide plates 221. The air guide plates 221 introduce the air volume of the diffuser 43 into the cold chamber frame 22 in proportion. The cold chamber frame 22 is also provided with an upper partition 222 and a lower partition 223. The upper partition 222 is placed between the upper layer and the lower layer of the cold chamber frame 22, and the lower partition is placed at the bottom layer of the cold chamber frame 22.

[0100] The evaporator 42 is used to provide cooling capacity for liquid wax cooling. It is mainly composed of 10# steel pipe, galvanized sheet, box, etc., all of which are galvanized. The cooling fan 44 blows the cooling capacity provided by the evaporator from the upper 7 layers of the cold room frame, and then returns to the evaporator through the lower 7 layers, re-cooling the wind after heat exchange with the wax tray group. The diffuser 43 diffuses the wind blown by the fan to the upper 7 layers. It is pressed and formed by galvanized sheet and fixed between the cold room and the cold room frame with bolts.

[0101] The driving mechanism 12 includes a main motor 121, a main motor sprocket 122, and a transmission sprocket 123. The main motor 121 is connected to the main motor sprocket 122, and the main motor sprocket 122 is connected to the transmission sprocket 123. A driving sprocket 124 is also connected to the upper part of the transmission sprocket 123. The driving sprocket 124 is connected to a plurality of flip sprockets 125. A tensioning sprocket 126 is provided at the far end of the flip sprocket 125, and a translation sprocket 127 is provided between the tensioning sprocket 126 and the flip sprocket 125.

[0102] The heat exchange system 13 includes a wax and water heat exchanger 131, a water and water heat exchanger 132, a water circulation pump 133, a wax regulating valve 134, a water regulating valve 135, a steam regulating valve 136, and a wax circulation pump 137. The wax and water heat exchanger 131 is conductively connected to the wax injection system 14 and the water and water heat exchanger 132, the water circulation pump 133 is conductively connected to the wax and water heat exchanger 131, the wax regulating valve 134 is conductively connected to the wax injection system 14, the water regulating valve 135 is conductively connected to the water circulation pump 133, the steam regulating valve 136 is arranged directly below the water circulation pump 133 and the water regulating valve 135, and the wax circulation pump 137 is conductively connected to the wax injection system 14.

[0103] The cold room wall and upper cover are made of 100mm thick flame-retardant polyurethane foam. Each foam board is 900mm wide, with concave and convex surfaces and socket installation. The conveyor 3 is composed of active rollers, driven rollers, rollers, conveyor belt reduction motors, etc. and wax trays. The function of the interlayer is to evenly distribute the wax tray group in 14 layers and conduct the wax tray group to the translation and tensioning device. The wax unloading mechanism is composed of a turning device, an upper top wheel, a lower top wheel, a canvas, a wax receiving plate, and a detection device. Its function is to turn over and demould the wax tray group coming out of the cold room.

[0104] The continuous formula must be discretized into a periodic sampling deviation formula, and the processing formula is as follows:

[0105]

[0106] in:

[0107] Mn is the calculated value of the loop output at sampling time n;

[0108] Kc is the loop gain;

[0109] En is the loop deviation value at sampling time n;

[0110] E(n-1) is the previous value of the loop deviation;

[0111] Ki is the proportional constant of the integral term;

[0112] Minitial is the initial value of the loop output;

[0113] Kd is the proportionality constant of the differential term.

[0114] From this formula, we can see that the integral term is a function of all error terms from the first sampling period to the current sampling period, the differential term is a function of the current sampling and the previous sampling, and the proportional term is only a function of the current sampling. In digital computers, not all error terms are saved, and in fact, it is not necessary.

[0115] Since the system must calculate the output value once for each deviation sample value starting from the first sampling, only the previous value of the deviation and the previous value of the integral term need to be saved. As a result of the repetitiveness of the system solution, a simplified formula for the equation that must be calculated at any sampling time can be obtained.

[0116] The simplified formula of the equation for sampling time calculation is:

[0117] in:

[0118] Mn loop output calculation value at sampling time n

[0119] MPn loop output proportional term value at sampling time n

[0120] The value of the loop output integral term at sampling time n

[0121] MDn is the value of the loop output differential term at sampling time n

[0122] The proportional term of the PID controller output adjustment principle formula is:

[0123] MP n =K C (SP n -PV n );

[0124] Among them, MP n is the value of the proportional term at the nth sampling moment;

[0125] Kc is the gain;

[0126] SP n is the given value at the nth sampling moment;

[0127] PV n PV n The process variable value.

[0128] The integral term of the PID controller output adjustment principle formula is:

[0129] MI n =K C *TS / TI*(SP n -PV n )+MX;

[0130] Among them, MI n is the integral term value at the nth sampling moment;

[0131] TS is the sampling time interval;

[0132] TI is the integration time;

[0133] SP n is the given value at the nth sampling moment;

[0134] PV n PV n The process variable value;

[0135] MX is the integrated value at the n-1th sampling moment.

[0136] The integral sum (MX) is the sum of all previous values ​​of the integral terms. After each calculation of MIn, MIn is used to update MX. MIn can be adjusted or limited. The initial value of MX is usually set to Minitial before the first output calculation. The integral term also includes several other constants: gain (KC), sampling time interval (TS) and integration time (TI). The sampling time is the time interval for recalculating the output, and the integration time controls the influence of the integral term on the entire output result.

[0137] The differential term of the PID controller output adjustment principle formula is: MD n =K C *T D / *((SP n -PV n )·(SP n-1 -PV n-1 )).

[0138] In order to execute PID instructions, certain parameters must be initialized and set, which can also be called tuning. Parameter tuning has a great impact on the control effect. The PID controller has four main parameters Ts, Kc, Ti and Td that need to be tuned.

[0139] In the three control actions of P, I, and D, the proportional (P) part is consistent with the error in time. As long as the error occurs, the proportional part can promptly produce a regulation effect proportional to the error, which has the characteristic of timely regulation. The larger the proportional coefficient Kc, the stronger the proportional regulation effect, but too large will aggravate the output oscillation of the system and reduce stability.

[0140] The integral (I) part is related to the size of the error and the history of the error. As long as the error is not zero, the output of the controller will continue to change due to the integral action. The integral part will not change until the error disappears and the system is in a stable state. Therefore, the integral part can eliminate the steady-state error and improve the control accuracy. However, the integral action is slow and has a strong lag, which may have an adverse effect on the dynamic stability of the system.

[0141] When the integral time constant Ti increases, the integral effect weakens, the dynamic stability of the system may change, but the speed of eliminating steady-state errors slows down.

[0142] The differential (D) part reflects the trend of the controlled quantity change, and the differential part gives a greater adjustment effect in advance based on it. It is more timely than proportional adjustment, so the differential part has the characteristics of advance and prediction. When the differential time constant Td increases, the overshoot may be reduced and the dynamic performance is improved, but the ability to suppress high-frequency interference decreases. If Td is too large, the system output may oscillate with a higher frequency.

[0143] PID parameter setting: It depends on experience and familiarity with the process, referring to the measured value tracking and set value curve to adjust the size of P\I\D.

[0144] Proportional I / differential D=2, the specific value can be determined according to the instrument, and then adjust the proportional band P. If P is too high, it will take a long time to reach stability. If P is too short, it will oscillate and will never meet the set requirements.

[0145] Engineering setting of PID controller parameters, empirical data of PID parameters in various adjustment systems can be referred to as follows:

[0146] Temperature T: P = 20 ~ 60%, Ti = 180 ~ 600s, TD = 3 ~ 180s;

[0147] Pressure P: P = 30-70%, Ti = 24-180s;

[0148] Liquid level L: P = 20 ~ 80%, Ti = 60 ~ 300s;

[0149] Flow rate L: P = 40 ~ 100%, Ti = 6 ~ 60s.

[0150] The size of the PID parameter setting should be determined according to the specific situation of the control object on the one hand; on the other hand, it should be judged based on experience. P is to solve the amplitude oscillation. If P is large, the amplitude oscillation will be large, but the oscillation frequency will be small, and the system will take a long time to reach stability; I is to solve the speed of action response. If I is large, the response speed will be slow, and vice versa; D is to eliminate static errors. Generally, D is set to a small value and has little impact on the system. For temperature control systems, P is between 5-10%; I is between 180-240s; D is below 30. For pressure control systems, P is between 30-60%; I is between 30-90s; D is below 30. Here is an empirical method. This method is essentially a trial and error method. It is an effective method summarized in production practice and has been widely used on site.

[0151] After the temperature of the incoming wax is exchanged through the wax-water heat exchanger, the temperature of the wax liquid is controlled within the range required by the process. This is the outer loop of the temperature control system. The final temperature of the liquid wax is affected by the temperature of the incoming wax and the temperature of the internal circulating water. When the temperature of the incoming wax remains unchanged, it is only affected by the temperature of the internal circulating water. Controlling the temperature of the internal circulating water also controls the temperature of the liquid wax. Therefore, the temperature control of the internal circulating water is the inner loop control system of this temperature control system. The temperature of the circulating water is controlled by controlling the feed amount of cooling water.

[0152] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement the scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for the ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. Temperature control system of weighing type paraffin continuous molding machine, characterized by: The machine comprises a head part (1) and a cold chamber part (2), wherein the head part (1) is mounted at the front end of the cold chamber part (2), the head part (1) comprises a head frame (11), a driving mechanism (12), a heat exchange system (13), a wax injection system (14) and a wax removal mechanism (15), wherein the driving mechanism (12) is mounted inside the head frame (11), the heat exchange system (13) is connected to the wax injection system (14), and the wax removal mechanism (15) is mounted at the rear side of the wax injection system (14); The cold chamber part (2) is connected to the head part (1) via a conveyor (3); the cold chamber part (2) comprises a cold chamber (21), a cold chamber frame (22), a translation mechanism (23), a tensioning mechanism (24) and a cooling mechanism (4); the cold chamber (21) is installed inside the cold chamber frame (22); the translation mechanism (23) and the tensioning mechanism (24) are installed on two sides of the cold chamber (21) relative to each other; the cooling mechanism (4) is installed at the bottom of the cold chamber (21); and the cold chamber frame (22) is provided with two groups of upper and lower partitions, and the partitions are evenly distributed; The cooling mechanism (4) comprises a cooling motor (41), an evaporator (42), a diffuser (43) and a cooling fan (44); the cooling motor (41) is connected to the cooling fan (44); the cooling fan (44) blows the cooling energy provided by the evaporator (42) into the lower layer through the upper layer of the cold chamber frame (22) and returns to the evaporator (42); the diffuser (43) diffuses the air volume of the cooling fan (44) to the upper layer of the cold chamber frame (22); the cold chamber frame (22) is provided with a plurality of air guide plates (221); the air guide plates (221) guide the air volume of the diffuser (43) into the cold chamber frame (22) in proportion; the cold chamber frame (22) is also provided with an upper partition plate (222) and a lower partition plate (223); the upper partition plate (222) is placed between the upper layer and the lower layer of the cold chamber frame (22); and the lower partition plate is placed at the bottom layer of the cold chamber frame (22); The heat exchange system (13) comprises a wax and water heat exchanger (131), a water and water heat exchanger (132), a water circulation pump (133), a wax regulating valve (134), a water regulating valve (135), a steam regulating valve (136), and a wax circulation pump (137); the wax and water heat exchanger (131) is conductively connected to the wax injection system (14) and the water and water heat exchanger (132); the water circulation pump (133) is conductively connected to the wax and water heat exchanger (131); the wax regulating valve (134) is conductively connected to the wax injection system (14); the water regulating valve (135) is conductively connected to the water circulation pump (133); the steam regulating valve (136) is arranged directly between the water circulation pump (133) and the water regulating valve (135); and the wax circulation pump (137) is conductively connected to the wax injection system (14).

2. The weighing type paraffin wax continuous molding machine temperature control system according to claim 1, characterized in that: The heat exchange system (13) adjusts the output through a PID controller, and the principle formula of the PID controller adjusting the output is as follows: Among them, M(t) is the loop output as a time function; KC is the loop gain; e is the loop deviation; M initial This is the initial value of the loop output.

3. The weighing type paraffin continuous molding machine temperature control system according to claim 2 is characterized in that: The continuous formula must be discretized into a periodic sampling deviation formula, and the processing formula is as follows: in: Mn is the calculated value of the loop output at sampling time n; Kc is the loop gain; En is the loop deviation value at sampling time n; E(n-1) is the previous value of the loop deviation; Ki is the proportional constant of the integral term; Minitial is the initial value of the loop output; Kd is the proportionality constant of the differential term.

4. The weighing type paraffin continuous molding machine temperature control system according to claim 3 is characterized in that: The simplified formula of the equation for calculating the sampling time is: in: Mn loop output calculation value at sampling time n MPn loop output proportional term value at sampling time n The value of the loop output integral term at sampling time n MDn is the value of the loop output differential term at sampling time n.

5. The temperature control system of the weighing type paraffin continuous molding machine according to claim 4 is characterized in that: The proportional term of the PID controller output adjustment principle formula is: MP n =K C (SP n -PV n ); Among them, MP n is the value of the proportional term at the nth sampling moment; Kc is the gain; SP n is the given value at the nth sampling moment; PV n PV n The process variable value.

6. The weighing type paraffin wax continuous molding machine temperature control system according to claim 5, characterized in that: The integral term of the PID controller output adjustment principle formula is: MI n =K C *TS / TI*(SP n -PV n )+MX; Among them, MI n is the integral term value at the nth sampling moment; TS is the sampling time interval; TI is the integration time; SP n is the given value at the nth sampling moment; PV n PV n The process variable value; MX is the integrated value at the n-1th sampling moment.

7. The weighing type paraffin wax continuous molding machine temperature control system according to claim 6, characterized in that: The differential term of the PID controller output adjustment principle formula is: MD n =K C *T D / *((SP n -PV n )·(SP n-1 -PV n-1 )).

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