CN117819275A - A constant speed and constant tension control method and system in a metal heat treatment process - Google Patents

Abstract

The invention discloses a constant-speed constant-tension control method and a constant-speed constant-tension control system in a metal heat treatment process, wherein equipment or the constant-speed constant-tension control system in the heat treatment process comprises an uncoiling device, a coiling device, a heat treatment furnace, a PLC control module, a straightening device, a speed sensor and a tension sensor, wherein the speed sensor is used for measuring the linear speed of heat treatment materials, the tension sensor is used for measuring the material tension in the heat treatment process, the uncoiling device and the coiling device are respectively provided with an adjustable rotating motor and an encoder, constant tension is loaded on the heat treatment metal materials, the constant linear speed is controlled, and according to a motor transfer function, a reasonable speed and tension fine adjustment method is designed, so that the constant-speed constant-tension control is realized, the problem that the traditional metal heat treatment only controls the angular speed of the motor, and the influence of fluctuation and overrun of the linear speed and the tension on the performance of the metal materials is ignored, and the product performance is more stable and the yield is higher is overcome.

Description

A constant speed and constant tension control method and system in a metal heat treatment process

Technical Field

The invention belongs to the technical field of metal heat treatment, and in particular relates to a constant speed and constant tension control method and system in a metal heat treatment process.

Background technique

During the processes of metal material processing, forming, composite rolling, etc., it is generally necessary to undergo heat treatment in a heating furnace, annealing furnace, preheating furnace (collectively referred to as a heat treatment furnace in the present invention), etc. to ensure the forming effect and performance of the metal material.

In the current heat treatment process of metal coils, such as titanium alloy strips, the metal material at the unwinding end is treated in a heat treatment furnace and then reeled in at the reeling end. This is a continuous dynamic process. Generally, only the angular velocity of the reeling device is set, and the unwinding end rotates passively to unload the material. The entire system rotates and reels at this constant angular velocity.

In this method, the actual running line speed of the metal material is low at the beginning of the winding process due to the small winding diameter. As the amount of material at the winding end increases, the diameter also increases. Under a constant angular velocity, the line speed of the material also increases. In other words, the running line speeds of different sections of material in the heat treatment furnace are different, and thus the heat treatment time in the heat treatment furnace is also different. In particular, the running line speeds of the starting section material and the last section material are quite different, which leads to a large difference in the heat treatment effect of the metal material. On the other hand, traditional heat treatment only performs constant angular velocity control, and does not consider the possible distortion and deformation of the metal strip material, which also leads to the final effect of the heat treatment of the metal material being often not ideal. Typical performance impacts on the product include uneven distribution of strength and toughness, distortion and deformation, and smaller tensile cross-section of the material.

Summary of the invention

In view of the above problems, the present invention designs a constant speed and constant tension control method and system in the metal heat treatment process. Through the joint control of the constant tension and constant linear speed of the heat-treated metal material, the performance of the heat-treated metal material can be guaranteed and the product quality rate can be greatly improved.

The invention discloses a constant speed and constant tension control method in a metal heat treatment process. The equipment or system of the heat treatment process includes an unwinding device, a winding device, a heat treatment furnace, a PLC control module and a straightening device, and also includes a speed sensor and a tension sensor. The speed sensor is used to measure the linear speed of the heat-treated material, and the tension sensor is used to measure the material tension during the heat treatment process. The unwinding device and the winding device are both provided with an adjustable speed rotating motor and an encoder, such as a traditional variable frequency motor. The straightening device is a commonly used device for metal heat treatment. The encoder is used to measure the rotation angle. The angular velocity and angular acceleration can be obtained by dynamic angle measurement. The method includes the following steps:

S0, unwinding and winding device optimization, unwinding and winding device motor optimization (with I-shaped wheels but without flat bars) when unwinding and winding devices are unloaded, so as to obtain the maximum angular acceleration α _max and moment of inertia I, and compare the load feedback curve with the theoretical load feedback curve. If the fluctuation deviation is within 2%, it is considered that the mechanical transmission mechanism meets the production requirements; this step is preparatory work, as long as the equipment has not changed significantly, it can be done once;

S1. Release the material, connect the unwinding device and the winding device, connect the material to the unwinding device and the winding device at both ends of the heat treatment furnace, start the heat treatment device in time (generally, the heat treatment device should be started before the winding device is started), so that the material can be processed by the heat treatment furnace and wound up with the rotation of the winding device;

S2, adjust the straightening device, press down the straightening device and fix it, at this time, a constant resistance F2 is generated in the direction of material movement, and the direction of the resistance is opposite to the direction of movement;

S3, static tension is applied. When the material is transferred from the unwinding device to the winding device and fixed on the winding device, the unwinding device and the winding device apply a reverse torque constituting a pulling force to apply static tension. The static tension is required to be within the first threshold range of the tension deviation. The first threshold of the tension deviation is a threshold range based on the target tension. The target tension value F _m = kbh, in units of N (Newton), wherein k is the tension control coefficient, b is the material width, and h is the material thickness, all in units of mm. When the measured tension F ₃ reaches the allowable deviation range of the target tension value F _m , the tension is maintained;

S4. Adjust the running speed. The motors of the unwinding device and the winding device gradually speed up from a static state (during the speed regulation process from a static state to the set value, the tension may deviate or fluctuate. The tension deviation or fluctuation is allowed to be within the second threshold of the tension deviation). When the deviation between the feedback value of the speed sensor and the set target speed reaches within the second threshold of the speed deviation, it is considered that the speed has reached the target value.

Furthermore, after the speed and tension are basically in place and stable (meeting the second threshold of speed deviation and the second threshold of tension deviation respectively), continue to make fine adjustments so that the speed and tension meet the first threshold of speed deviation and the first threshold of tension deviation respectively, and the first threshold of speed deviation is less than the second threshold of speed deviation.

Furthermore, the angular velocity control method of the winding device and the unwinding device includes an angular velocity control method based on the Archimedean spiral equation.

Furthermore, the constant tension control method includes: the tension is given by the PLC control module and sends signals to the motor inverters of the unwinding device and the winding device at the same time, with the unwinding device torque being adjusted as the main priority and the winding device torque being adjusted as the auxiliary, and the tension is increased or decreased accordingly. When the tension sensor feedback tension reaches the set target value, the tension coarse adjustment is stopped; it is judged whether the tension fluctuation meets the requirements, if not, the unwinding device or the winding device is fine-tuned to make the tension fluctuation close to its mean value, and the PLC output signal is maintained.

Furthermore, the constant speed control method includes that after the material tension is adjusted, the operator gives a target speed V on the operation interface, and calculates the frequency adjustment amount, the voltage adjustment amount or the current adjustment amount according to V=rα ₀ t and the motor transfer function.

Wherein, α ₀ is the set step adjustment angular acceleration, α ₀ ≤α _max .

Furthermore, when the speed exceeds the limit and/or the tension exceeds the limit, the adopted control method includes over-limit control method 1 or over-limit control method 2.

Furthermore, the first over-limit control method includes, when the measured speed exceeds the tolerance:

S41, the PLC control module issues an adjustment command, and the winding device motor fine-tunes the speed value according to "speed fine-tuning amount = speed excess difference amount * first proportional coefficient k ₁ ", and waits until the speed is basically stable;

S42, comparing the actual measured tension value to see if it exceeds the tolerance. If the tension does not exceed the tolerance, compare the speed again to see if it still exceeds the tolerance. If both are not exceeded, the adjustment is completed. If the speed still exceeds the tolerance, continue to fine-tune the speed according to the last adjustment amount and then re-compare the tension to see if it exceeds the tolerance. If the tension exceeds the tolerance, the unwinding device fine-tunes the tension value according to "tension fine-tuning amount = tension excess tolerance amount * second proportional coefficient k ₂ ";

S43, wait for a certain period of time again, after the tension is basically stable (re-compare whether the speed exceeds the tolerance, if there is an excess, repeat the above S41~S43 process; if there is no excess in speed and tension, complete the over-limit control;

The second over-limit control method includes, when the measured tension exceeds the tolerance,

S4a, the PLC control module issues an adjustment command, and the unwinding device motor fine-tunes the tension value according to "tension fine-tuning amount = tension excess difference amount * second proportional coefficient k ₂ ", and waits until the tension is basically stable;

S4b, compare the actual speed value to see if it exceeds the tolerance. If it does not, compare the tension again to see if it still exceeds the tolerance. If it does not, complete the adjustment. If the tension still exceeds the tolerance, continue to fine-tune the tension according to the last adjustment amount and then re-compare the speed to see if it exceeds the tolerance. If the speed exceeds the tolerance, the winding device fine-tunes the speed value according to "speed fine-tuning amount = speed deviation amount * first proportional coefficient k ₁ ";

S4c, wait for a certain period of time again, and after the speed is basically stable, re-compare whether the tension is out of tolerance. If there is an out of tolerance, repeat the above S4a~S4c process; if there is no out of tolerance in both speed and tension, complete the over-limit control;

When the measured speed and tension are out of tolerance at the same time (both exceed their respective first deviation thresholds), over-limit control method 1 or over-limit control method 2 is adopted.

Furthermore, when the measured speed and tension are both out of tolerance, tension control is performed first and speed control is performed as an auxiliary.

On the other hand, a constant speed and constant tension control system in a metal heat treatment process adopts a constant speed and constant tension control method in a metal heat treatment process as described in any one of claims 1 to 8.

Furthermore, the system sequentially arranges an unwinding device, a straightening device, a tension speed measuring device, a heat treatment furnace and a winding device, the unwinding device, the tension speed measuring device and the winding device are electrically connected to the PLC control module respectively, the tension speed measuring device comprises a speed sensor and a tension sensor, the speed sensor is used to measure the linear speed of the heat-treated material, the tension sensor is used to measure the material tension during the heat treatment process, the unwinding device and the winding device are both provided with an adjustable speed rotating motor and an encoder, the heat treatment furnace comprises a heating section, a soaking section and a cooling section.

The advantages and beneficial effects of the present invention are as follows: a constant speed and constant tension control method and system in a metal heat treatment process designed by the present invention can ensure that the heat and force in the metal heat treatment process are uniform and stable, and the crystal structure of the final product is uniform and changes little, and there is no shrinkage problem (the cross-sectional size is basically unchanged before and after annealing). Taking the heat treatment of titanium alloy strips as an example, when unwinding and cutting for use, there is no autonomous deformation, and the product quality rate is greatly improved. The traditional method heat treats about 1500m of metal coil at a time, and the quality rate is about 80%. After the improvement, the quality rate can reach more than 97%. The defective products are mainly the starting section and the ending section, and the two ends can be directly removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a connection diagram of a constant speed and constant tension control system in a metal heat treatment process;

FIG2 is a block diagram of a constant speed and constant tension control method in a metal heat treatment process;

FIG3 is a block diagram of an over-limit control method;

FIG4 is a block diagram of the second over-limit control method.

Detailed ways

The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

Example 1

The present invention is designed to control a constant speed and constant tension in a metal heat treatment process. As shown in FIG1 , the equipment or system of the heat treatment process includes an unwinding device, a winding device, a heat treatment furnace, a PLC control module and a straightening device. The equipment or system of the heat treatment process also includes a speed sensor and a tension sensor. The speed sensor is used to measure the linear speed of the heat treatment material, and the tension sensor is used to measure the material tension during the heat treatment process. The unwinding device and the winding device are both provided with an adjustable speed rotating motor and an encoder, such as a traditional variable frequency motor. The straightening device is a commonly used device for metal heat treatment. The encoder is used to measure the rotation angle, and the angular velocity and angular acceleration can be obtained through dynamic angle measurement. The straightening device in this embodiment is implemented by a roller group with upper and lower offsets. The speed sensor and the tension sensor are integrated in design and adopt a three-wheel structure. The inlet is an auxiliary wheel, the outlet is a speed measuring wheel, and the middle is a tension measuring wheel. The co-location of the speed sensor and the tension sensor is called a tension speed measuring device. The constant tension refers to a constant winding tension, and the constant speed refers to a constant winding linear speed, that is, to ensure that the tension and speed of the material in the heat treatment furnace are constant. As shown in FIG2 , the method includes the following steps:

S0, unwinding and winding device optimization, unwinding and winding device when no-load motor optimization (with I-shaped wheels but without flat bars), so as to obtain the maximum angular acceleration α _max and moment of inertia I (for updating transfer function parameters), by comparing the load feedback curve with the theoretical load feedback curve, if the fluctuation or deviation is within 2%, it is considered that the mechanical transmission mechanism meets the production requirements, this embodiment directly uses the built-in optimization software of the inverter for test optimization; this step is not required for each heat treatment, a set of equipment should generally be optimized once before use, and the relevant parameters should be obtained, and no major performance changes or fault repairs are required in the future, and the latest optimization result can be used directly; it is generally recommended that even if there is no abnormality, optimization should be performed regularly, such as every six months or every year.

S1. Release the material, connect the unwinding device and the winding device, connect the material to the unwinding device and the winding device at both ends of the heat treatment furnace, start the heat treatment device in time (generally, the heat treatment device should be started before the winding device is started), so that the material can be processed by the heat treatment furnace and wound up with the rotation of the winding device;

S2, adjust the straightening device, press down the straightening device and fix it, at this time, a constant resistance F2 is generated in the direction of material movement, and the direction of the resistance is opposite to the direction of movement;

S3, static tension is applied. When the material is transferred from the unwinding device to the winding device and fixed on the winding device, the unwinding device and the winding device apply a reverse torque constituting a pulling force. In this embodiment, the unwinding device applies a left-turning torque (counterclockwise), and the winding device applies a right-turning torque (clockwise). Static tension is applied. The actual measured value of the static tension is required to be within the first threshold range of the tension deviation. The first threshold of the tension deviation is a threshold range based on the target tension. The target tension value F _m = kbh, in units of N (Newton), wherein k is the tension control coefficient, in this embodiment, k = 2-5 N/mm ² , b is the material width, and h is the material thickness, both in units of mm. When the actual measured tension F ₃ reaches the allowable deviation range of the target tension value F _m , the tension is maintained. In this embodiment, the first threshold of the allowable tension deviation is set to ±3% of the target tension value, that is, |F ₃ -F _m |/F _m ≤0.03; as shown in FIG1 , the straightening device, the speed sensor, and the tension sensor are in a static tensioning state F ₃ = F ₁ +F m at this time. ₂ , where _F1 is the unwinding tension and the measured tension _F3 is the winding tension;

The basic method of tension control is tension F = T*D = U*K*D, where T is the motor torque, D is the I-shaped wheel diameter, U is the inverter output voltage, K is the motor torque coefficient, and the tension loading speed Af is the set value F = Af*t, t is the continuous loading time, F includes _F1 and _F3 , and other parameters are the corresponding opening and winding device parameters.

S4. Adjust the running speed. The motors of the unwinding device and the winding device gradually speed up from a static state (during the speed regulation process from a static state to the set value, the tension may fluctuate or deviate. The tension fluctuation or deviation is allowed to be controlled within the second threshold of the tension deviation. If it exceeds the deviation range, it should be adjusted. In this embodiment, the second threshold of the tension deviation is set to ±5% of the target tension value). When the deviation between the feedback value of the speed sensor and the set target speed reaches within the second threshold of the speed deviation, it is considered that the speed reaches the target value. In this embodiment, the second threshold of the speed deviation is set to ±5% of the target speed value. The equipment or system of the heat treatment process performs heat treatment on the material according to the set speed and tension until completion. The running speed is the linear speed of the material, which is essentially achieved by adjusting the angular velocity of the motor.

When the diameter of the unwinding device becomes smaller and the rotation speed (angular velocity) approaches the set value ω ₀ =V ₀ /(πD), the PLC outputs a command to inform that the coil is low and needs to be changed, where V ₀ is the set linear speed, π is the circumference, and D is the bottom diameter of the I-wheel or the minimum coil diameter.

Generally, a frequency converter controls a motor by changing the output voltage, current or frequency to change the state of the motor. In this embodiment, the torque corresponding to the motor output is changed by adjusting the voltage, thereby adjusting the tension, and the speed of the motor is changed by adjusting the frequency of the frequency converter.

Preferably, after the speed and tension are basically in place and stable (meeting the second threshold requirements of speed deviation and the second threshold requirements of tension deviation, respectively), continue to fine-tune the speed and tension so that they meet the first threshold requirements of speed deviation and the first threshold requirements of tension deviation, respectively. The first threshold of speed deviation is less than the second threshold of speed deviation. In this embodiment, the first threshold of speed deviation is ±4% of the target speed value.

Preferably, the angular velocity control method of the winding device and the unwinding device includes an angular velocity control method based on the Archimedean spiral equation.

The angular velocity control method based on the Archimedean spiral equation is as follows: During the operation of the system, the change in the winding diameter r (radius or diameter, calculated by radius in this embodiment) of the material during winding and unwinding follows the Archimedean spiral equation, that is,

r＝a+cθ

Where a is the distance from the winding starting point to the origin of the polar coordinates, which is a constant; c = h/(2π) is the value that increases with each unit angle r of the spiral line, that is, the angle increases by 360 degrees for each rotation, and the radius increases by the thickness of the material h; θ is the continuous winding angle of the Archimedean spiral, expressed in radians. In fact, the winding point θ = 0, and θ = 4π for two consecutive rotations;

By differentiating the time, we can get the relationship between the linear velocity V and the angular velocity ω based on the Archimedean spiral equation:

V＝cθ ² +(a+cθ)ω

Thus there is

ω＝(V-cθ ² )/(a+cθ)

That is, the angular velocity of the winding and unwinding device can be determined in real time according to the constant linear velocity requirement and the rotation angle of the Archimedean spiral. It should be noted here that since the general strip material is wound with a non-continuous Archimedean spiral, different layers of materials follow the Archimedean spiral equation, and the same layer of material may have multiple turns, but they have the same coil diameter and their angular velocity is also consistent. That is, for the winding method of materials with multiple turns in the same layer, the angular velocity control of the open roll should be a segmented angular velocity control method based on the Archimedean spiral equation plus a same angular velocity control method between segments (materials in the same layer). For the winding method with only one turn per layer, that is, the winding is a continuous Archimedean spiral, the control method is relatively simple, and the angular velocity control method based on the Archimedean spiral equation can be directly adopted.

Preferably, the constant speed control method includes: after the material tension is adjusted, the operator gives a target speed V on the operation interface. In this embodiment, the line speed control is mainly based on the winding speed, and the PLC simultaneously gives the speed instruction to the unwinding and winding frequency converter (or vice versa). The speed is calculated according to V=rα ₀ t and the motor transfer function to calculate the frequency adjustment amount, voltage adjustment amount or current adjustment amount. In this embodiment, the speed is mainly adjusted by adjusting the motor frequency, and the data is adjusted once per second. When the speed measured by the speed meter is consistent with the set speed, the speed control ends.

Wherein, α ₀ is the set step adjustment angular acceleration, α ₀ ≤ α _max , and in this embodiment, α _o = α _max /2.

In order to implement the control method, the unwinding device and the rewinding device should be provided with an angle measuring instrument and/or an angular velocity measuring instrument. In this embodiment, encoders are respectively provided to perform real-time angle measurement.

Example 2

The difference from Example 1 is that this embodiment considers tension fine-tuning, and the constant tension control method includes: the tension is given by the PLC control module and the motor frequency converter of the unwinding device and the winding device is sent a signal at the same time, so as to give priority to adjusting the torque of the unwinding device as the main, and to adjust the torque of the winding device as the auxiliary (adjusting the torque can change the tension, at least when the unwinding motor torque is adjusted once and the target is not reached, according to the actual effect, such as when the unwinding motor torque is close to the maximum value or is obviously larger, or the effect is not obvious after multiple adjustments, it can be considered to adjust the torque of the winding motor. The priority adjustment and priority control described in the present invention can be understood with reference to this), the tension is increased or decreased accordingly, and the tension coarse adjustment is stopped when the tension sensor feedback tension reaches the set target value; it is judged whether the tension fluctuation meets the requirements. In this embodiment, less than 1% of the mean is used as the judgment condition. If not, the unwinding device or the winding device is fine-tuned to make the tension fluctuation close to its mean, that is, the tension is fine-tuned to reduce the fluctuation to within 1%, and the PLC output signal is maintained.

To avoid excessive impact, motor adjustment is usually based on the stepping method, such as increasing/decreasing the output value of voltage, current or frequency by one frame per second. The step amount is mainly based on being able to achieve adjustment quickly and smoothly, which is called coarse adjustment. After the adjustment is basically in place, the step amount is reduced for fine-tuning.

When adjusting the speed over a large range, it is also possible to distinguish between coarse adjustment and fine adjustment and their combination.

Generally, the combination of coarse adjustment and fine adjustment is used when static tension is applied and operation is started. Fine adjustment is used when large fluctuations/exceeding limits occur in tension or speed during operation.

Example 3

The difference from Example 2 is that when the speed exceeds the limit and/or the tension exceeds the limit, the control method used includes the over-limit control method 1 or the over-limit control method 2. Because when one of the speed and tension changes, it will affect the change of the other. Therefore, when controlling, it is necessary to control these two parameters separately, cyclically fine-tune, and gradually approach the target value. The over-limit mentioned in the present invention includes the actual measured value exceeding the limit during fluctuation. When the fluctuation is large, the fine-tuning method is generally adopted, that is, reducing the frequency, voltage or current step amount, adjusting the tension and/or speed. This embodiment is implemented according to the unwinding device giving priority to controlling the tension and the winding device giving priority to controlling the speed.

Preferably, as shown in FIG3 , the first over-limit control method includes, when the measured speed exceeds the tolerance (exceeds the allowable range of the target speed, in this embodiment, the first threshold value of the speed deviation is taken):

S41, the PLC control module issues an adjustment command, and the motor of the winding device fine-tunes the speed value according to "speed fine-tuning amount = speed deviation amount * first proportional coefficient k ₁ " (actually, the PLC fine-tunes the frequency of the inverter according to the speed fine-tuning amount and the motor transfer function), and in this embodiment k ₁ =50%; since speed adjustment will inevitably affect the tension change, it is necessary to wait for a certain time, generally waiting until the speed is basically stable (in this embodiment, the speed is basically stable after 5s of fine-tuning);

S42, comparing the actual measured tension value to see if it exceeds the tolerance (exceeds the target tension allowable range, and in this embodiment, the first threshold value of the tension deviation is used). If the tension does not exceed the tolerance, compare again to see if the speed still exceeds the tolerance. If both are not exceeded, the adjustment is completed. If the speed still exceeds the tolerance, continue to fine-tune the speed according to the last adjustment amount and then re-compare to see if the tension exceeds the tolerance. If the tension exceeds the tolerance, the unwinding device fine-tunes the tension value according to "tension fine-tuning amount = tension excess tolerance amount * second proportional coefficient k ₂ " (actually, the PLC fine-tunes the motor voltage or current according to the fine-tuning tension fine-tuning amount and the motor transfer function). In this embodiment, k ₂ = 30%;

S43, wait for a certain period of time again, after the tension is basically stable (in this embodiment, after the tension is fine-tuned for 5 seconds), re-compare whether the speed is out of tolerance, if there is an out of tolerance, repeat the above S41-S43 process; if both the speed and the tension are within the tolerance, then complete the over-limit control. In the figure, two diamond blocks are used to express the judgment of whether the tension is out of tolerance, which is essentially the same thing, but the program flowchart is drawn in this way just to express the situation that both the speed and the tension are within the tolerance;

The second over-limit control method includes, when the measured tension exceeds the tolerance (exceeds the target tension allowable range, that is, the over-limit is too large, and the first threshold value of the tension deviation is taken in this embodiment), as shown in FIG4,

S4a, the PLC control module issues an adjustment command, and the unwinding device motor fine-tunes the tension value according to "tension fine-tuning amount = tension deviation amount * second proportional coefficient k ₂ ", which is actually the PLC fine-tuning the motor voltage or current according to the tension fine-tuning amount and the motor transfer function). In this embodiment, k ₂ =30%, and wait until the tension is basically stable (in this embodiment, the tension is basically stable after 5s of fine-tuning);

S4b, compare the actual speed value to see if it exceeds the tolerance (exceeds the target speed allowable range, in this embodiment, the first threshold value of the speed deviation is taken). If it does not exceed the tolerance, compare again to see if the tension still exceeds the tolerance. If it does not exceed the tolerance, the adjustment is completed. If the tension still exceeds the tolerance, continue to fine-tune the tension according to the last adjustment amount and then re-compare to see if the speed exceeds the tolerance. If the speed exceeds the tolerance, the winding device fine-tunes the speed value according to "speed fine-tuning amount = speed excess tolerance amount * first proportional coefficient _k1 " (actually, the PLC fine-tunes the frequency of the inverter according to the speed fine-tuning amount and the motor transfer function). In this embodiment, _k1 = 50%;

S4c, wait for a certain period of time again, and after the speed is basically stable (in this embodiment, after the speed is fine-tuned for 5 seconds), re-compare whether the tension is out of tolerance. If there is an out-of-tolerance, repeat the above S4a to S4c process; if there is no out-of-tolerance in both speed and tension, complete the over-limit control; the difference between the control method 2 and the control method 1 mainly lies in the interchange of tension and speed, the interchange of winding and unwinding devices, and the fine-tuning amount is carried out according to the respective set ratios.

When the measured speed and tension are out of tolerance at the same time (both exceed the first threshold of their respective deviations), over-limit control method 1 or over-limit control method 2 is adopted.

If the adjustment strategy is that the winding device prioritizes tension control and the unwinding device prioritizes speed control, the over-limit control method 1 and the over-limit control method 2 only need to make adaptive changes to the device objects, and the basic principles, methods and steps remain unchanged.

Preferably, when the measured speed and tension are both out of tolerance, tension control is performed first, and speed control is performed as an auxiliary, such as the second over-limit control method. This design mainly takes into account that the speed change mainly affects the heat treatment time of the material in the heat treatment furnace, and the impact on the material performance is not immediately reflected; while the tension directly affects the material performance by affecting the internal organizational structure of the material, so adjusting the tension first can reduce the impact of the over-limit on the material performance. If the over-limit range of both speed and tension is not large, the actual impact of the adjustment sequence is not obvious.

Example 4

The difference from Example 3 is that this embodiment is implemented by controlling the tension by the winding device and the speed by the unwinding device.

Example 5

A constant speed and constant tension control system in a metal heat treatment process, wherein the system adopts a constant speed and constant tension control method in a metal heat treatment process as described in any one of Examples 1 to 4, or a preferred combination thereof.

Preferably, the system sequentially arranges an unwinding device, a straightening device, a tension speed measuring device, a heat treatment furnace and a winding device, the unwinding device, the tension speed measuring device and the winding device are electrically connected to the PLC control module respectively, the tension speed measuring device comprises a speed sensor and a tension sensor, the speed sensor is used to measure the linear speed of the heat treatment material, the tension sensor is used to measure the material tension during the heat treatment process, the unwinding device and the winding device are both provided with an adjustable speed rotating motor and an encoder, the heat treatment furnace comprises a heating section, a soaking section and a cooling section.

The basic principle of the present invention is: by setting a tension and speed monitoring device, according to the real-time monitoring results and the physical parameters and transfer function model of the unwinding device and the winding device, the unwinding device and the winding device are adjusted in steps to achieve the tension and speed approaching the target value, so that the metal material can complete the heat treatment process with a relatively stable cycle and tension, so that the internal crystal structure of the metal is more uniform, the performance is more stable, and there is no shrinkage phenomenon; in the initialization and startup process of the heat treatment, the straightening device is preferentially set to load the static tension, and then the speed is loaded, and the system is gradually started to the target tension and speed. The system can enter a steady state at a faster speed, and the efficiency can be improved while ensuring product performance.

The above is only a part of the more systematic and comprehensive constant speed and constant tension control method and system implementation scheme in the metal heat treatment process of the present invention. In fact, the speed and tension can be adjusted directly by fine-tuning. During static startup, the tension can be loaded during or after startup. In dynamic conditions, the speed can be adjusted first and then the tension, especially when there are deviations in tension and speed but the speed deviation is large. These combinations or preferred schemes should also be regarded as the scope of protection of the present invention and will not be listed one by one here.

Claims (10)

1. A constant speed and constant tension control method in a metal heat treatment process, wherein the equipment or system of the heat treatment process comprises an unwinding device, a winding device, a heat treatment furnace, a PLC control module and a straightening device, characterized in that the equipment or system of the heat treatment process further comprises a speed sensor and a tension sensor, wherein the speed sensor is used to measure the linear speed of the heat-treated material, and the tension sensor is used to measure the material tension during the heat treatment process, and the unwinding device and the winding device are both provided with an adjustable speed rotary motor and an encoder, and the method comprises the following steps: S1, releasing the material, and connecting the material to an unwinding device and a winding device at both ends of the heat treatment furnace; S2. Adjust the straightening device, press down the straightening device and fix it. At this time, a constant resistance F2 is generated in the direction of material movement; S3, static tension is applied. When the material is transferred from the unwinding device to the winding device and fixed on the winding device, the unwinding device and the winding device apply a reverse torque constituting a pulling force to apply static tension. The static tension is required to be within the first threshold range of the tension deviation. The first threshold range of the tension deviation is a threshold range based on the target tension. The target tension value F _m = kbh, where k is the tension control coefficient, b is the material width, and h is the material thickness. S4. Adjust the running speed. The motors of the unwinding device and the winding device gradually increase their speed from a static state. When the deviation between the feedback value of the speed sensor and the set target speed reaches within the second threshold of the speed deviation, it is considered that the speed reaches the target value. 2. According to claim 1, a constant speed and constant tension control method in a metal heat treatment process is characterized in that after the speed and tension are in place and stable, fine-tuning is continued so that the speed and tension meet the requirements of the first speed deviation threshold and the first tension deviation threshold respectively, and the first speed deviation threshold is less than the second speed deviation threshold. 3. According to a constant speed and constant tension control method in a metal heat treatment process according to claim 1, it is characterized in that the angular velocity control method of the winding device and the unwinding device includes an angular velocity control method based on the Archimedean spiral equation. 4. According to a constant speed and constant tension control method in a metal heat treatment process according to claim 1, it is characterized in that the constant speed control method includes, after the material tension adjustment is completed, giving a target speed V, and calculating the frequency adjustment amount, voltage adjustment amount or current adjustment amount according to the motor transfer function. 5. A constant speed and constant tension control method in a metal heat treatment process according to claim 1, characterized in that the constant tension control method includes: the tension is given by the PLC control module and a rotation signal is sent to the unwinding device and the winding device at the same time, with the unwinding device torque being adjusted as the main priority and the winding device torque being adjusted as the auxiliary, and the tension is roughly adjusted to follow the increase or decrease, and the tension coarse adjustment is stopped when the measured tension value reaches the first threshold range of the tension deviation; it is judged whether the tension fluctuation meets the requirements, if not, the unwinding device or the winding device is fine-tuned to make the tension fluctuation close to its mean value, and the PLC output signal is maintained. 6. A constant speed and constant tension control method in a metal heat treatment process according to any one of claims 1 to 5, characterized in that when the speed exceeds the limit and/or the tension exceeds the limit, the control method adopted includes over-limit control method one or over-limit control method two. 7. A constant speed and constant tension control method in a metal heat treatment process according to claim 6, characterized in that the over-limit control method 1 includes, when the measured speed exceeds the tolerance, S41, the PLC control module issues an adjustment command, and the winding device motor fine-tunes the speed value according to "speed fine-tuning amount = speed deviation amount * first proportional coefficient k ₁ ", and waits until the speed is stable; S42, comparing the actual measured tension value to see if it is out of tolerance, if not, comparing the speed again to see if it is still out of tolerance, if both are not out of tolerance, the adjustment is completed, if the speed is still out of tolerance, continue to fine-tune the speed according to the last adjustment amount and then re-compare the tension to see if it is out of tolerance; if the tension is out of tolerance, the unwinding device fine-tunes the tension value according to "tension fine-tuning amount = tension out of tolerance amount * second proportional coefficient k ₂ "; S43, after the tension is stable, re-compare the speed to see if there is an error. If there is an error, repeat the above S41 to S43 process; if there is no error in both the speed and the tension, complete the over-limit control; The second over-limit control method includes, when the measured tension exceeds the tolerance, S4a, the PLC control module issues an adjustment command, and the unwinding device motor fine-tunes the tension value according to "tension fine-tuning amount = tension excess difference amount * second proportional coefficient k ₂ ", and waits until the tension is stable; S4b, compare the actual speed value to see if it exceeds the tolerance. If it does not, compare the tension again to see if it still exceeds the tolerance. If it does not, complete the adjustment. If the tension still exceeds the tolerance, continue to fine-tune the tension according to the last adjustment amount and then re-compare the speed to see if it exceeds the tolerance. If the speed exceeds the tolerance, the winding device fine-tunes the speed value according to "speed fine-tuning amount = speed deviation amount * first proportional coefficient k ₁ "; S4c, after the speed is stable, re-compare the tension to see if it is out of tolerance. If it is, repeat the above S4a to S4c process; if both the speed and tension are within tolerance, the over-limit control is completed; When the measured speed and tension are out of tolerance at the same time, use over-limit control method 1 or over-limit control method 2. 8. A constant speed and constant tension control method in a metal heat treatment process according to claim 7, characterized in that when the measured speed and tension are both out of tolerance, tension control is performed first and speed control is performed as an auxiliary. 9. A constant speed and constant tension control system in a metal heat treatment process, characterized in that the system adopts a constant speed and constant tension control method in a metal heat treatment process as described in any one of claims 1 to 8. 10. A constant speed and constant tension control system in a metal heat treatment process according to claim 9, characterized in that the system is sequentially provided with an unwinding device, a straightening device, a tension speed measuring device, a heat treatment furnace and a winding device, the unwinding device, the tension speed measuring device and the winding device are electrically connected to the PLC control module respectively, the tension speed measuring device comprises a speed sensor and a tension sensor, the speed sensor is used to measure the linear speed of the heat treatment material, the tension sensor is used to measure the material tension during the heat treatment process, and the unwinding device and the winding device are both provided with an adjustable speed rotating motor and an encoder.