Temperature control system of screw extrusion molding machine

Abstract

The invention relates to the technical field of temperature control, and particularly discloses a temperature control system of a screw extrusion forming machine, which comprises the following steps: judging and obtaining an extrusion abnormal signal, checking a feeding section, judging and obtaining a feeding section preheating qualification signal, and checking a compression section cylinder of the screw extrusion forming machine based on the feeding section preheating qualification signal; the method comprises the following steps: obtaining a compression section temperature qualified signal, checking and judging the metering section temperature of the screw extrusion molding machine based on the compression section temperature qualified signal to obtain a metering section temperature qualified signal, and cooling or heating one or more parts of which the temperature values are not in a preheating temperature value domain [JLb, JLs]. The temperature of the barrel in the compression section is regulated and controlled, the temperature of the barrel in the metering section and / or the temperature of the metering outlet end are / is adjusted, stable operation of the screw extrusion forming machine in the product production and extrusion process is guaranteed, and the operation efficiency of the screw extrusion forming machine is improved.

Description

Technical Field

[0001] This invention relates to the field of temperature control technology, and more specifically to a temperature control system for a screw extrusion molding machine. Background Technology

[0002] During the operation of a screw extruder, it is necessary to control the temperature of multiple working sections within the barrel to obtain products of acceptable quality. Temperature regulation inside the barrel is generally achieved through heating components and cooling structures outside the barrel. Traditional screw extruders typically only measure and control the temperature inside the barrel, resulting in low precision and a high likelihood of product defects during production.

[0003] During the product extrusion process, unstable temperature or excessive temperature difference in any part may lead to problems such as cracks, bubbles, and deformation. Manual control is time-consuming, labor-intensive, and increases material waste. In order to ensure the quality of products produced by screw extruders, we control multiple sections of the screw extrusion molding machine barrel to improve the adjustment accuracy and speed, and ensure the stability of the temperature inside the screw extruder. Summary of the Invention

[0004] The purpose of this invention is to provide a temperature control system for a screw extrusion molding machine to solve the problems mentioned above.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A temperature control system for a screw extrusion molding machine includes:

[0007] Product detection module: Real-time acquisition of the outer diameter of the extruded product after being extruded by the extrusion molding machine through a light curtain sensor and construction of a product model; identification and acquisition of extrusion abnormality signals;

[0008] Feeding section inspection module: Based on the extrusion anomaly signal, the feeding section is inspected, the temperature data value set P of the feeding section is obtained, and the preheating qualification signal of the feeding section is determined and obtained.

[0009] Compression Section Inspection Module: Based on the preheating qualification signal of the feeding section, inspect the compression section cylinder of the screw extrusion molding machine;

[0010] This includes: uniformly distributing markings within the compression section cylinder, labeling each marking as n, where n is 1, 2, 3…; acquiring the compression section temperature value at each marking point within the compression section cylinder using a temperature sensor, and labeling it as YS. n ;

[0011] The stable temperature value TYSB of the compression section cylinder is calculated and compared with the stable temperature threshold Tysb of the compression section cylinder to obtain the temperature fluctuation signal of the compression section.

[0012] Based on the stable temperature signal of the compression section, the average temperature YSJ of the compression section point marked inside the compression section cylinder is calculated, and the qualified temperature signal of the compression section is obtained.

[0013] Metering Section Inspection Module: Based on the qualified temperature signal of the compression section, the module inspects the temperature of the metering section of the screw extrusion molding machine, determines and obtains the qualified temperature signal of the metering section.

[0014] As a further aspect of the present invention: the anomaly ratio WY of the outer diameter per unit length segment during the extrusion process is calculated and compared with the threshold WYZ of the anomaly ratio of the outer diameter per unit length segment.

[0015] If the abnormal ratio of outer diameter per unit length segment WY is greater than the threshold WYZ for the abnormal ratio of outer diameter per unit length segment, an extrusion abnormality signal is generated.

[0016] If the abnormal ratio of outer diameter per unit length segment WY is less than or equal to the threshold WYZ, an extrusion stabilization signal is generated.

[0017] As a further aspect of the present invention, the specific working steps of the feed section inspection module include:

[0018] Obtain the maximum and minimum values ​​in the feed section temperature data set P, denoted as JLmax and JLmin respectively. Calculate the feed section anomaly value JY and compare it with the anomaly extreme value Jj. At the same time, determine whether the highest feed temperature value JLmax and the lowest feed temperature value JLmin are within the preheating temperature range [JLb, JLs].

[0019] If the feed section anomaly value JY is less than or equal to the anomaly extreme value Jj, and the highest feed temperature value JLmax and the lowest feed temperature value JLmin are both within the preheating temperature range [JLb, JLs], a feed section preheating qualified signal is generated.

[0020] Otherwise, a signal indicating that the preheating of the feeding section is unqualified will be generated.

[0021] As a further aspect of the present invention: the method for obtaining the stable temperature value TYSB of the compression section cylinder in the compression section inspection module includes the following steps:

[0022] Obtain the maximum and minimum values ​​of the temperature at the compression point inside the compression section cylinder, and label them as the maximum temperature at the compression point YSmax and the minimum temperature at the compression point YSmin, respectively.

[0023] The extreme value of temperature deviation at the compression section point is obtained by calculating YSZD = YSmax - YSmin.

[0024] Meanwhile, the standard deviation value YSBC of the temperature at the compression section point is calculated using the standard deviation formula;

[0025] The number of points whose temperature values ​​in the compression section are not within the melting temperature range [RRb,RRs] is recorded as e;

[0026] Then, through The stable temperature value TYSB of the compression section cylinder is calculated, where a and b are preset proportional coefficients, and both a and b are greater than 0.

[0027] As a further aspect of the present invention: in the compression section inspection module, the stable temperature value TYSB of the compression section cylinder is compared with the stable temperature threshold Tysb of the compression section cylinder.

[0028] If the stable temperature value TYSB of the compression section cylinder is greater than the stable temperature threshold Tysb of the compression section cylinder, a temperature fluctuation signal of the compression section is generated.

[0029] If the stable temperature value TYSB of the compression section cylinder is less than or equal to the stable temperature threshold Tysb of the compression section cylinder, a stable temperature signal of the compression section is generated.

[0030] The average temperature YSJ of the compression section is calculated at the marked points inside the compression section cylinder. If the average temperature YSJ is within the melting temperature range [RRb, RRs], a qualified temperature signal for the compression section is generated. If the average temperature YSJ is greater than the maximum qualified temperature RRs, a high temperature signal for the compression section is generated. If the average temperature YSJ is less than the minimum qualified temperature RRb, a low temperature signal for the compression section is generated.

[0031] As a further aspect of the present invention: in the metering section inspection module, it is simultaneously determined whether the metering section cylinder temperature value CL and the metering outlet temperature value CK are within the metering extrusion temperature range [JCb, JCs].

[0032] If both the metering section cylinder temperature CL and the metering outlet temperature CK are within the metering extrusion temperature range [JCb, JCs], ​​a temperature difference evaluation signal is generated.

[0033] If the temperature value CL of the metering section cylinder and / or the temperature value CK of the metering outlet are not within the metering extrusion temperature range [JCb, JCs], ​​an abnormal temperature signal of the metering section is generated.

[0034] As a further aspect of the present invention: in the metering section inspection module, the temperature difference value JTK at the metering section outlet is compared with the temperature difference threshold JTKy at the metering section outlet;

[0035] If the temperature difference value JTK at the metering section outlet is less than or equal to the temperature difference threshold JTKy at the metering section outlet, a temperature qualification signal for the metering section is generated.

[0036] If the temperature difference value JTK at the metering section outlet is greater than the temperature difference threshold JTKy at the metering section outlet, a signal indicating that the temperature difference in the metering section is too large is generated.

[0037] As a further aspect of the present invention: the feeding section control module cools or heats one or more parts of the feeding section cylinder.

[0038] As a further aspect of the present invention: a compression section control module for controlling the temperature of the cylinder in the compression section.

[0039] As a further aspect of the present invention: the metering section inspection module adjusts the temperature of the metering section cylinder and / or the metering outlet end.

[0040] The beneficial effects of this invention are:

[0041] By measuring and detecting the product per unit length during the extrusion process of the screw extruder, when product size abnormalities occur, the temperature of each working section of the screw extruder is checked and adjusted in a timely manner to ensure the stable operation of the screw extruder during product production. This solves the problem of unqualified extruded products caused by temperature abnormalities in the feeding section, compression section, and metering section of the screw extruder during operation. The adjustment process is rapid, meeting the effect of automatic control. Compared with the manual inspection process, it effectively reduces the inspection and control time and improves the operating efficiency of the screw extruder. Attached Figure Description

[0042] The invention will now be further described with reference to the accompanying drawings.

[0043] Figure 1 This is a schematic diagram of the system modules of the present invention. Figure 1 ;

[0044] Figure 2 This is a schematic diagram of the system modules of the present invention. Figure 2 . Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Example 1

[0047] Please see Figure 1 and Figure 2 As shown, the present invention is a temperature control system for a screw extrusion molding machine, comprising:

[0048] Product inspection module: The light curtain sensor acquires the outer diameter data of the extruded product after it is extruded by the extrusion molding machine in real time, and simulates the acquired outer diameter data into the extrusion molding space coordinate system to build a product model;

[0049] Based on the product model in the extrusion molding spatial coordinate system, obtain the product outer diameter value of the unit length segment L, obtain the continuous abnormal product length segments whose product outer diameter value is not within the qualified value range of the product outer diameter, and mark them as YL;

[0050] pass The abnormal ratio of the outer diameter per unit length of the product during the extrusion process, WY, is calculated.

[0051] Compare the anomaly ratio of outer diameter per unit length segment WY with the threshold WYZ for the anomaly ratio of outer diameter per unit length segment:

[0052] If the abnormal ratio of the outer diameter per unit length segment WY is greater than the threshold WYZ, an extrusion abnormality signal is generated. At this time, the feeding section, compression section and metering section of the screw extrusion molding machine need to be checked in sequence.

[0053] If the abnormal ratio of outer diameter per unit length segment WY is less than or equal to the threshold WYZ of the abnormal ratio of outer diameter per unit length segment, an extrusion stabilization signal is generated; at this time, the screw extrusion molding machine is kept running normally.

[0054] Feed section troubleshooting module: Based on extrusion anomaly signals, the feed section of the screw extrusion molding machine is investigated. Temperature data set P of the feed section is obtained through temperature sensors. The feed section temperature data set P includes the feed inlet temperature value JLT, the screw channel temperature value JLCT, and the hopper area temperature value JLDT.

[0055] The maximum and minimum values ​​in the temperature data set P of the feed section are obtained and denoted as JLmax and JLmin, respectively. The feed section anomaly value JY is calculated by JY = JLmax - JLmin.

[0056] Compare the feed section anomaly value JY with the anomaly extreme value Jj. At the same time, determine whether the highest feed temperature value JLmax and the lowest feed temperature value JLmin are within the preheating temperature range [JLb, JLs].

[0057] If the feed section anomaly value JY is less than or equal to the anomaly extreme value Jj, and the highest feed temperature value JLmax and the lowest feed temperature value JLmin are both within the preheating temperature range [JLb, JLs], a feed section preheating qualified signal is generated. It should be noted that JLb is the minimum qualified value of the feed section, and JLs is the maximum qualified value of the feed section. This indicates that during the operation of the screw extrusion molding machine, the temperature and temperature difference of each part of the feed section structure are in a qualified operating state. At this time, it is necessary to continue to check other parts of the screw extrusion molding machine.

[0058] Otherwise, a signal indicating that the preheating of the feeding section is unqualified will be generated;

[0059] Compression Section Inspection Module: Based on the preheating pass signal of the feeding section, the compression section cylinder of the screw extruder is inspected, specifically including the following steps:

[0060] S31: Uniformly distributed markings are made inside the compression section cylinder, and each marking is labeled n, where n is 1, 2, 3... The temperature value of the compression section point inside the compression section cylinder is obtained by a temperature sensor and marked as YS. n ;

[0061] S32: Obtain the maximum and minimum values ​​of the temperature at the compression point inside the compression section cylinder, and mark them as the maximum temperature at the compression point YSmax and the minimum temperature at the compression point YSmin, respectively.

[0062] The extreme value of temperature deviation at the compression section point is obtained by calculating YSZD = YSmax - YSmin.

[0063] Meanwhile, the standard deviation value YSBC of the temperature at the compression section point is calculated using the standard deviation formula;

[0064] The number of points whose temperature values ​​in the compression section are not within the melting temperature range [RRb,RRs] is recorded as e;

[0065] Then, through The temperature stability value TYSB of the compression section cylinder was calculated, where a and b are preset proportionality coefficients, and both a and b are greater than 0; a is 0.32 and b is 0.68.

[0066] By calculating the standard deviation and extreme value of the temperature at several points in the compression section, the stable temperature value of the compression section cylinder is obtained. This can be used to determine whether there are large fluctuations or temperature differences between the temperature values ​​at various points in the compression section of the screw extrusion molding machine, so as to determine whether the temperature operation of the compression section is normal.

[0067] S33: Compare the stable temperature value TYSB of the compression section cylinder with the stable temperature threshold Tysb of the compression section cylinder;

[0068] If the stable temperature value TYSB of the compression section cylinder is greater than the stable temperature threshold Tysb of the compression section cylinder, a temperature fluctuation signal of the compression section is generated.

[0069] If the stable temperature value TYSB of the compression section cylinder is less than or equal to the stable temperature threshold Tysb of the compression section cylinder, a stable temperature signal of the compression section is generated.

[0070] S34: Based on the temperature stability signal of the compression section, through The average temperature YSJ of the compression section point marked inside the compression section cylinder was calculated.

[0071] Determine whether the average temperature of the compression section, YSJ, is within the melting temperature range [RRb, RRs]. It should be noted that RRb is the minimum acceptable value for the compression section, and RRs is the maximum acceptable value for the compression section.

[0072] If the average temperature of the compression section YSJ is within the melting temperature range [RRb, RRs], a qualified temperature signal for the compression section is generated; at this time, the metering section of the screw extrusion molding machine needs to be checked.

[0073] If the average temperature of the compression section YSJ is greater than the maximum acceptable temperature RRs of the compression section, a high temperature signal for the compression section is generated.

[0074] If the average temperature of the compression section YSJ is less than the minimum acceptable value RRb of the compression section, a low temperature signal for the compression section is generated.

[0075] Metering Section Inspection Module: Based on the qualified temperature signal of the compression section, the metering section temperature of the screw extruder is inspected. The specific steps are as follows:

[0076] S41: The temperature values ​​CL of the metering section cylinder and CK of the metering outlet are obtained by measuring and acquiring the temperature value CK of the metering outlet through temperature sensors;

[0077] S42: Simultaneously determine whether the metering section cylinder temperature value CL and the metering outlet temperature value CK are within the metering extrusion temperature range [JCb, JCs]; where JCb is the minimum qualified value of the metering extrusion temperature of the metering section, and JCs is the maximum qualified value of the metering extrusion temperature of the metering section.

[0078] If both the metering section cylinder temperature value CL and the metering outlet temperature value CK are within the metering extrusion temperature range [JCb, JCs], ​​a temperature difference evaluation signal is generated; at this time, S43 is executed.

[0079] If the temperature value CL of the metering section cylinder and / or the temperature value CK of the metering outlet are not within the metering extrusion temperature range [JCb,JCs], ​​an abnormal temperature signal of the metering section is generated.

[0080] S43: Based on the temperature difference evaluation signal, the temperature difference value JTK at the cylinder inlet of the metering section is calculated by JTK=|CL-CK|;

[0081] Compare the temperature difference value JTK at the metering section cylinder outlet with the temperature difference threshold value JTKy at the metering section cylinder outlet;

[0082] If the temperature difference value JTK at the metering section cylinder opening is less than or equal to the temperature difference threshold JTKy at the metering section cylinder opening, a temperature qualified signal for the metering section is generated. At this time, it indicates that the feeding section, compression section and metering section are all in normal temperature condition, and other reasons need to be checked.

[0083] If the temperature difference value JTK at the metering section outlet is greater than the temperature difference threshold JTKy at the metering section outlet, a signal indicating that the temperature difference in the metering section is too large is generated.

[0084] Example 2

[0085] Based on the above embodiment 1, when the feeding section is detected to have a signal of unqualified preheating, it is necessary to control the abnormal temperature parts in the feeding section preheating process.

[0086] Based on this, this embodiment provides a feeding section control module that adjusts the temperature within the feeding section of the screw extrusion molding machine based on a preheating failure signal, including the following adjustment methods:

[0087] A: If the feed section anomaly value JY is greater than the anomaly extreme value Jj, and the highest feed temperature value JLmax and the lowest feed temperature value JLmin are both within the preheating temperature range [JLb, JLs], then it indicates that the temperature difference between the feed inlet temperature value JLT, the screw channel temperature value JLCT and the hopper area temperature value JLDT in the feed section is too large. In this case, the median value in the feed section temperature data set P is recorded as JLmid.

[0088] At this point, the intermediate value JLmid in the temperature data set P is subtracted from the maximum value JLmax and the minimum value JLmin, and the absolute value is taken.

[0089] If |JLmid-JLmax|>|JLmid-JLmin|, then the maximum temperature value in the feed section temperature data set P will be cooled down.

[0090] If |JLmid-JLmax| < |JLmid-JLmin|, then the minimum temperature value in the feed section temperature data set P will be heated.

[0091] If |JLmid-JLmax|=|JLmid-JLmin|, then the maximum temperature value in the feed section temperature data set P is cooled down, and the minimum temperature value in the feed section temperature data set P is heated up.

[0092] B: If the feed section anomaly value JY is less than the anomaly extreme value Jj, and the highest feed temperature value JLmax and / or the lowest feed temperature value JLmin are not in the preheating temperature range [JLb,JLs], then it means that the temperature difference between the feed inlet temperature value JLT, the screw channel temperature value JLCT and the hopper area temperature value JLDT in the feed section meets the standard, but there is one or more temperature values ​​that are not in the preheating temperature range [JLb,JLs].

[0093] At this point, one or more parts whose temperature values ​​are not in the preheating temperature range [JLb,JLs] can be directly cooled down or heated up.

[0094] C: If the feed section anomaly value JY is greater than the anomaly extreme value Jj, and the highest feed temperature value JLmax and / or the lowest feed temperature value JLmin are not within the preheating temperature range [JLb,JLs], then it indicates that the temperature difference between the feed inlet temperature value JLT, the screw channel temperature value JLCT and the hopper area temperature value JLDT in the feed section is too large, and there is one or more temperature values ​​that are not within the preheating temperature range [JLb,JLs].

[0095] At this point, one or more parts whose temperature values ​​are not in the preheating temperature range [JLb,JLs] are first cooled down or heated up to adjust the temperature values ​​to be within the preheating temperature range [JLb,JLs]. Then, the feed section anomaly value is recalculated and it is determined whether it is less than or equal to the anomaly extreme value Jj.

[0096] If the recalculated difference value of the feed section is less than or equal to the extreme difference value Jj, then the adjustment is complete;

[0097] If the recalculated feed section anomaly value is greater than the extreme anomaly value Jj, then step A in this embodiment is executed.

[0098] Example 3

[0099] Based on the above embodiment 1, when the compression section temperature fluctuation signal, high compression section temperature signal, and low compression section temperature signal are obtained during the compression inspection, it is necessary to adjust the temperature anomaly occurring in the compression section. This embodiment provides a compression section control module, specifically including:

[0100] U: If a temperature fluctuation signal is obtained in the compression section, it indicates that the temperature values ​​at n marked points in the compression section cylinder are unstable during the operation of the screw extrusion molding machine. In this case, the screw extrusion molding machine needs to be stopped and restarted to reheat the temperature in the compression section in order to further determine whether the abnormal operation of the compression section in the screw extrusion molding machine is an occasional occurrence and whether it is necessary to stop the machine for maintenance.

[0101] V: If a high temperature signal is received in the compression section, it indicates that the excessively high temperature in the compression section during the screw extrusion molding process can cause the product particles to overheat and melt, leading to localized degradation and surface abnormalities after extrusion. In this case, it is necessary to cool the inside of the compression section cylinder. Specifically:

[0102] Q1: The cooling value JWT of the compression section is obtained by calculating JWT = YSJ - RRs;

[0103] Obtain the mass flow rate m and specific heat capacity cp of the product within the compression section;

[0104] At this point, the target reduction value of shear heat Qj is obtained by calculating Qj = JWT × m × cp;

[0105] Q2: Obtain basic data for the screw extrusion molding machine, including: screw radius r, real-time screw speed N, distance h between screw outer diameter and inner wall of the barrel, volume ν of the screw groove in the compression section, and operating shear heat time ψ; at the same time, obtain material data, including the viscosity value τ of the product material;

[0106] The operating shear heat value Qy is calculated;

[0107] Specifically:

[0108] Q3: At this point, the target shear heat value Qm is obtained by calculating Qm = Qy - Qj;

[0109] At this time, through The target screw rotation speed M is calculated.

[0110] Q4: At this point, in order to ensure the stable operation of the screw extrusion molding machine and the stable melting of the product material, it is necessary to compare the target screw speed value M with the rated minimum screw speed value Me.

[0111] If the target screw speed M is greater than or equal to the rated minimum screw speed Me, then the real-time screw speed N can be directly adjusted to the target screw speed M.

[0112] If the target screw speed M is less than the rated minimum screw speed Me, then reducing the real-time screw speed will not be sufficient to reduce the temperature. Instead, the real-time screw speed N can be kept constant, the heater power can be reduced directly, and the cooling fan can be started to cool down quickly, so that the average point temperature YSJ of the compression section is reduced to the maximum acceptable value RRs of the compression section.

[0113] W: If a low compression section temperature signal is received, this indicates that the material may not fully melt and plasticize during the operation of the screw extruder. This can lead to problems such as unmelted or unevenly melted product particles, resulting in surface abnormalities after extrusion. In this case, it is necessary to raise the temperature inside the compression section cylinder. Specifically:

[0114] P1: The temperature rise value SWT of the compression section is obtained by calculating SWT = RRb - YSJ;

[0115] Obtain the mass flow rate m and specific heat capacity cp of the product within the compression section;

[0116] At this point, the target increase in shear heat, Qs, is obtained by calculating Qs = SWT × m × cp.

[0117] P2: Obtain basic data for the screw extrusion molding machine, including: screw radius r, real-time screw speed N, distance h between screw outer diameter and inner wall of the barrel, volume ν of the screw groove in the compression section, and operating shear heat time ψ; at the same time, obtain material data, including the viscosity value τ of the product material;

[0118] The operating shear heat value Qy is calculated;

[0119] Specifically:

[0120] P3: At this point, the target shear heat value Qm is obtained by calculating Qm = Qy + Qs;

[0121] At this time, through The target screw rotation speed M is calculated.

[0122] P4: At this point, in order to ensure the stable operation of the screw extrusion molding machine and the stable melting of the product material, it is necessary to compare the target screw speed value M with the rated maximum screw speed value ME.

[0123] If the target screw speed M is greater than or equal to the rated maximum screw speed ME, then the real-time screw speed N can be directly adjusted to the target screw speed M.

[0124] If the target screw speed M is less than the rated maximum screw speed ME, then increasing the real-time screw speed will not be enough to achieve the temperature reduction effect. Instead, the real-time screw speed N can be kept constant, and the heater power can be directly increased to heat up quickly and raise the average point temperature YSJ of the compression section to the minimum qualified value RRb of the compression section.

[0125] Example 4

[0126] Based on the above embodiments, in a situation where an abnormality is detected in the preheating of the metering section during inspection and detection, it is necessary to adjust the abnormal part of the metering section. Therefore, this embodiment provides a metering section adjustment module, including:

[0127] X: Based on the abnormal temperature signal of the metering section, it should be noted that when the system performs abnormal detection on each stage during the operation of the screw extrusion molding machine, if the detection reaches the metering section, it means that there are no abnormalities in the feeding section and the compression section. At this time, under the abnormal temperature signal of the metering section, the adjustment process should not affect the feeding section and the compression section. Since the screw speed of the screw extrusion molding machine affects the temperature of the compression section, the screw speed must be kept stable during the adjustment of the metering section.

[0128] At this time, if the metering section barrel temperature value CL is not within the metering extrusion temperature range [JCb, JCs], ​​the heater power is increased or decreased to adjust the metering section barrel temperature value CL to within the metering extrusion temperature range [JCb, JCs]. It should be noted that when the metering section barrel temperature value CL is less than the minimum acceptable value for metering extrusion temperature, the heater power is increased; when the metering section barrel temperature value CL is greater than the maximum acceptable value for metering extrusion temperature, the heating power is decreased. At the same time, in order to cool down quickly, cooling can also be assisted by a fan or liquid cooling.

[0129] If the metering outlet temperature CK is not within the metering extrusion temperature range [JCb, JCs], ​​then the metering outlet temperature needs to be adjusted. At this time, heat will also be generated due to the friction between the screw and the metering section cylinder. However, adjusting the screw speed will affect the temperature of the compression section. Therefore, when adjusting the metering outlet temperature, the screw speed is not adjusted, but the extrusion pressure is adjusted. During the extrusion process of the screw extrusion molding machine, if the extrusion pressure is too high when the molten material enters the die from the metering section outlet, the material temperature will increase, which will affect the temperature at the metering section outlet. When the back pressure increases, the temperature will rise.

[0130] Therefore, when the metering outlet temperature CK is less than the minimum acceptable metering extrusion temperature JCb, the extrusion pressure can be increased. Specifically:

[0131] K11: The temperature rise value LSW in the metering section is obtained by calculating LSW = JCb - CK. Then, the specific heat capacity cp and material density ρ of the material in the metering section are obtained. The extrusion pressure rise value MP is obtained by calculating MP = LSW × cp × ρ.

[0132] K12: Obtain the extrusion pressure value YP of the metering section, and calculate the target value MY of the extrusion pressure of the metering section by MY=YP+MP;

[0133] Compare the target value MY of the metering section extrusion pressure with the safe value QY of the extrusion pressure;

[0134] If the target value of the metering section extrusion pressure MY is greater than the safe value of the extrusion pressure QY, then excessively increasing the extrusion pressure may cause safety hazards. In this case, it is possible to keep the metering section extrusion pressure value YP unchanged and directly increase the heater power to heat it up quickly, so that the metering outlet temperature value CK in the metering section rises to the minimum qualified value of the metering extrusion temperature JCb.

[0135] If the target value of the metering section extrusion pressure MY is less than or equal to the safe value of the extrusion pressure QY, then directly increasing the metering section extrusion pressure value YP to the target value of the metering section extrusion pressure MY will meet the requirement of increasing the metering outlet temperature value CK.

[0136] Y: When the metering outlet temperature CK is greater than the maximum acceptable metering extrusion temperature JCs, the extrusion pressure can be reduced. Specifically:

[0137] K21: The temperature drop value LJW in the metering section is obtained by calculating LJW = CK - JCs. Then, the specific heat capacity cp and material density ρ of the material in the metering section are obtained. The extrusion pressure reduction value MJ is obtained by calculating MJ = LJW × cp × ρ.

[0138] K22: Obtain the extrusion pressure value YP of the metering section, and calculate the target value MY of the extrusion pressure of the metering section by MY = YP - MJ;

[0139] Compare the target value of the metering section extrusion pressure MY with the rated value of the extrusion pressure QE;

[0140] If the target value of the metering section extrusion pressure MY is greater than the rated value of the extrusion pressure QE, then the requirement to reduce the metering section extrusion pressure YP to the target value of the metering section extrusion pressure MY can be met.

[0141] If the target value of the metering section extrusion pressure MY is less than or equal to the rated value of the extrusion pressure QE, then reducing the extrusion pressure too much may cause unstable extrusion. In this case, you can choose to keep the metering section extrusion pressure value YP unchanged, directly reduce the heater power, and cooperate with the cooling system to reduce the metering outlet temperature value CK in the metering section to the maximum qualified value of the metering extrusion temperature JCs.

[0142] It should be explained that extrusion pressure is a factor in the stable operation of a screw extrusion molding machine. Too low an extrusion pressure cannot guarantee the normal operation of extrusion production, while too high an extrusion pressure may lead to safety hazards such as excessive pressure and internal overheating.

[0143] Z: Based on the signal of excessive temperature difference in the metering section, the fastest adjustment method can be adopted, namely, increasing or decreasing the heater power to adjust the temperature value CL of the metering section cylinder, so that the temperature difference between the temperature value CL of the metering section cylinder and the temperature value CK of the metering outlet is closer, and the temperature difference value JTK at the metering section cylinder outlet is less than or equal to the temperature difference threshold JTKy at the metering section cylinder outlet.

[0144] By measuring and detecting the product per unit length during the extrusion process of the screw extruder, when product size abnormalities occur, the temperature of each working section of the screw extruder is checked and adjusted in a timely manner to ensure the stable operation of the screw extruder during product production. This solves the problem of unqualified extruded products caused by temperature abnormalities in the feeding section, compression section, and metering section of the screw extruder during operation. The adjustment process is rapid, meeting the effect of automatic control. Compared with the manual inspection process, it effectively reduces the inspection and control time and improves the operating efficiency of the screw extruder.

[0145] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A temperature control system for a screw extrusion molding machine, characterized in that, include: Product inspection module: Constructs a product model, obtains continuous abnormal product length segments YL on the unit length segment L of the product; calculates the abnormal ratio of the outer diameter of the unit length segment WY, and judges and obtains the extrusion abnormal signal; Feed section troubleshooting module: Based on extrusion anomaly signals, obtain the feed section temperature data set P, including the feed inlet temperature JLT, screw channel temperature JLCT, and hopper area temperature JLDT; The anomaly value JY of the feeding section is calculated, and the preheating qualification signal of the feeding section is determined and obtained. Compression Section Inspection Module: Based on the preheating qualification signal of the feeding section, uniformly distributed markings are made inside the compression section cylinder, and each marking is labeled as n, where n is 1, 2, 3... The temperature value of the compression section at each marking point inside the compression section cylinder is obtained through temperature sensors and marked as YS. n ; The stable temperature value TYSB of the compression section cylinder is calculated and compared with the stable temperature threshold Tysb of the compression section cylinder to obtain the stable temperature signal of the compression section; the average temperature value YSJ of the compression section point marked inside the compression section cylinder is calculated to obtain the qualified temperature signal of the compression section. Metering section inspection module: Based on the qualified temperature signal of the compression section, obtain the temperature value CL of the metering section cylinder and the temperature value CK of the metering outlet; judge and obtain the temperature difference evaluation signal; then calculate the temperature difference value JTK at the cylinder outlet of the metering section through JTK=|CL-CK|; judge and obtain the qualified temperature signal of the metering section.

2. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, In the product testing module, through The abnormal ratio of the outer diameter per unit length of the product during the extrusion process, WY, is calculated. If the abnormal ratio of outer diameter per unit length segment WY is greater than the threshold WYZ, an extrusion anomaly signal is generated; otherwise, an extrusion stability signal is generated.

3. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, The specific working steps of the feeding section inspection module include: The maximum and minimum values ​​in the temperature data set P of the feed section are obtained and denoted as JLmax and JLmin, respectively. The feed section anomaly value JY is calculated by JY = JLmax - JLmin. If the feed section anomaly value JY is less than or equal to the anomaly extreme value Jj, and the highest feed temperature value JLmax and the lowest feed temperature value JLmin are both within the preheating temperature range [JLb, JLs], a feed section preheating qualified signal is generated. Otherwise, a signal indicating that the preheating of the feeding section is unqualified will be generated.

4. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, In the compression section inspection module, the method for obtaining the stable temperature value TYSB of the compression section cylinder includes the following steps: Obtain the maximum and minimum values ​​of the temperature at the compression point inside the compression section cylinder, and label them as the maximum temperature at the compression point YSmax and the minimum temperature at the compression point YSmin, respectively. The extreme value of temperature deviation at the compression section point is obtained by calculating YSZD = YSmax - YSmin; the standard deviation value of temperature at the compression section point is obtained by calculating YSBC using the standard deviation formula. The number of points whose temperature values ​​in the compression section are not within the melting temperature range [RRb,RRs] is recorded as e; Then, through The stable temperature value TYSB of the compression section cylinder is calculated, where a and b are preset proportional coefficients, and both a and b are greater than 0.

5. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, In the compression section investigation module, if the stable temperature value TYSB of the compression section cylinder is greater than the stable temperature threshold Tysb of the compression section cylinder, a temperature fluctuation signal of the compression section is generated. Otherwise, generate a temperature stabilization signal for the compression section; Based on the temperature stability signal of the compression section, through The average temperature YSJ of the compression section point marked inside the compression section cylinder was calculated. If the average temperature of the compression section YSJ is greater than the maximum acceptable temperature RRs of the compression section, a high temperature signal for the compression section is generated. If the average temperature of the compression section YSJ is less than the minimum acceptable value RRb of the compression section, a low temperature signal for the compression section is generated. Otherwise, generate a signal indicating that the temperature of the compression section is within acceptable limits.

6. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, In the metering section inspection module, it is simultaneously determined whether the metering section cylinder temperature value CL and the metering outlet temperature value CK are within the metering extrusion temperature range [JCb, JCs]. If both the metering section cylinder temperature value CL and the metering outlet temperature value CK are within the metering extrusion temperature range [JCb, JCs], ​​a temperature difference evaluation signal is generated; otherwise, a metering section temperature anomaly signal is generated.

7. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, In the metering section inspection module, the temperature difference value JTK at the metering section outlet is compared with the temperature difference threshold JTKy at the metering section outlet. If the temperature difference value JTK at the metering section outlet is less than or equal to the temperature difference threshold JTKy at the metering section outlet, a signal indicating that the metering section temperature is within acceptable limits is generated; otherwise, a signal indicating that the temperature difference in the metering section is too large is generated.

8. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, It also includes a feeding section control module, which is used to cool or heat one or more parts of the feeding section cylinder.

9. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, It also includes a compression section control module, the working steps of which include: If a high temperature signal is received in the compression section, the interior of the compression section cylinder will be cooled down. Specifically: The cooling value JWT of the compression section is obtained by calculating JWT = YSJ - RRs; Obtain the mass flow rate m and specific heat capacity cp of the product within the compression section; calculate the target reduction value of shear heat Qj using Qj=JWT×m×cp; Obtain basic data of the screw extrusion molding machine, including screw radius r, real-time screw speed N, distance h between screw outer diameter and inner wall of barrel, volume ν of screw groove in compression section and operating shear heat time ψ; obtain material data, including product viscosity value τ; calculate operating shear heat value Qy; Specifically: The target shear heat value Qm is obtained by calculating Qm = Qy - Qj; then... The target screw rotation speed M is calculated. If the screw target speed value M is greater than or equal to the screw rated minimum speed value Me, adjust the screw real-time speed value N to the screw target speed value M; If the target screw speed M is less than the rated minimum screw speed Me, reduce the heater power so that the average point temperature YSJ of the compression section is reduced to the maximum qualified value RRs of the compression section. If a low temperature signal is obtained in the compression section, adjust the average temperature YSJ of the compression section point temperature to increase it to the minimum acceptable value RRb of the compression section.

10. The temperature control system for a screw extrusion molding machine according to claim 1, characterized in that, It also includes a metering section investigation module, the working steps of which include: When the metering outlet temperature value CK is less than the minimum acceptable value for metering extrusion temperature JCb: The temperature rise value LSW in the metering section is obtained by calculating LSW = JCb - CK. Then, the specific heat capacity cp and material density ρ of the material in the metering section are obtained. The extrusion pressure rise value MP is obtained by calculating MP = LSW × cp × ρ. Obtain the extrusion pressure value YP of the metering section, and calculate the target value MY of the extrusion pressure of the metering section using MY = YP + MP; If the target value of the extrusion pressure MY in the metering section is greater than the safe value of the extrusion pressure QY, increase the heater power so that the metering outlet temperature CK in the metering section rises to the minimum qualified value of the metering extrusion temperature JCb. If the target value of the metering section extrusion pressure MY is less than or equal to the safe value of the extrusion pressure QY, the extrusion pressure value YP of the metering section will be increased to the target value of the metering section extrusion pressure MY. If the metering outlet temperature value CK is greater than the maximum acceptable value of the metering extrusion temperature JCs, adjust the metering outlet temperature value CK in the metering section to reduce it to the maximum acceptable value of the metering extrusion temperature JCs.

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