A radiation thickness gauge and its calculation method of temperature compensation coefficient

Abstract

The present invention discloses a method for calculating the temperature compensation coefficient of a ray thickness gauge, belonging to the field of steel production, including: step (1) obtaining the temperature compensation coefficient K; step (2) setting the deviation limit amplitude; step (3) obtaining the digital temperature signal; step (4) temperature compensation; step (5) obtaining the cold state thickness value of the strip. Compared with the prior art, the present invention can improve the thickness detection accuracy, avoid the influence of abnormal temperature zones on thickness calculation and detection, achieve the purpose of accurately measuring the thickness, crown and wedge of the strip, and improve the product quality and production stability at the same time.

Description

Technical Field

[0001] The present invention relates to a measurement and calculation method, in particular to a radiation thickness gauge suitable for strip thickness detection and a calculation method for its temperature compensation coefficient. Background Art

[0002] Steel rolling is an important link in the production of steel by steel enterprises, and thickness is the key to determining the quality of steel. Different from length and width, the strip thickness cannot be cut and processed according to customer requirements. The strip thickness must be accurately detected and controlled during the rolling process. Therefore, a high-precision thickness gauge must be used in the production process to detect the real-time strip thickness. When the radiation thickness gauge measures the thickness, it is necessary to convert the detected hot-state thickness value of the strip into a cold-state thickness value. The temperature compensation coefficient used in the algorithm is calculated based on the temperature measured by the single-point pyrometer inside the thickness gauge. However, in the thin slab continuous casting and rolling production line, since there is no traditional gas heating furnace in front of the rough rolling stand for heating, there is generally an uneven temperature distribution across the strip. If the strip temperature in the detection area of the point pyrometer is abnormal, calculating the strip temperature compensation coefficient based on this will inevitably cause a large deviation in the conversion process of hot and cold state thickness values. The strip thickness, crown, and wedge calculated in this way will have large errors, which is not conducive to controlling the strip shape and quality.

[0003] Therefore, our company has developed "A Temperature Compensation Method and Device for Improving the Detection Accuracy of Radiation Thickness Gauges" (Application No. CN202011579550.5). This set of equipment includes a thickness gauge and a scanning pyrometer. The scanning pyrometer detects the temperature across the entire cross-section of the strip, and the collected signals are connected to a dedicated processor for processing and then transmitted to the thickness gauge control system through serial port or Ethernet, etc. The temperature compensation calculation program block in the thickness gauge control system is used to calculate the temperature compensation coefficients at each point in the width direction; and a deviation value is set to correct the data. However, the formula of the temperature compensation calculation method of this equipment uses the calculation method in the inherent calculation program block in the thickness gauge control system. This calculation method is based on single-point calculation. In the actual production process, when this kind of coefficient calculation formula is applied to multi-point calculation, there is a large deviation from the actual result.

[0004] Therefore, there is an urgent need for a temperature detection and temperature compensation coefficient calculation method for radiation thickness gauges suitable for thin slab continuous casting and rolling production lines. Summary of the Invention

[0005] The technical task of the present invention is to overcome the above deficiencies in the prior art and provide a temperature detection and temperature compensation coefficient calculation method for a radiation thickness gauge to improve the thickness detection accuracy, avoid the influence of abnormal temperature zones on thickness calculation and detection, achieve the purpose of accurately measuring the strip thickness, crown, and wedge, and at the same time improve product quality and production stability.

[0006] The technical solution of the present invention to solve the technical problem is: a method for calculating the temperature compensation coefficient of a ray-type thickness gauge, characterized by comprising the following steps:

[0007] Step (1): Obtain the temperature compensation coefficient K

[0008] Assuming S2 is the hot thickness value at different temperature values and S1 is the cold thickness value of the strip, the temperature compensation coefficient and the hot and cold thickness of the strip (1) can be expressed as:

[0009] K = (S2 - S1) / S1;

[0010] Take a standard thickness sample, heat it to different temperatures under laboratory conditions, and use a radiographic thickness gauge to measure the thickness of the standard sample under the condition of canceling temperature compensation. The compensation coefficient at different temperatures is obtained, and it is fitted with the temperature value into a sixth-order polynomial curve. The expression formula of temperature compensation coefficient and temperature is obtained (2): K = 1.082e -18 *t 6 -4.054e -15 *t 5 +6e -12 *t 4 -3.065e -9 *t 3 -1e -6 *t 2 +0.0015t+0.596

[0011] Write formula (1) and formula (2) into the temperature compensation program of the thickness gauge control system;

[0012] Step (2): Set the deviation limit value

[0013] Set the deviation limit value in the temperature compensation program of the thickness gauge control system;

[0014] Step (3): Obtain digital temperature signal

[0015] The pyrometer measures the surface radiation heat energy in the width direction of the strip, and transmits the measurement signal to the temperature measurement system processor, which amplifies and performs A / D conversion on the measured temperature value, and transmits the digital temperature signal to the temperature measurement control system;

[0016] Step (4): Temperature compensation

[0017] The temperature data of each point on the cross section collected in step (3) is connected to the temperature compensation program of the thickness gauge control system in step (1);

[0018] If the temperature in the width direction does not exceed the deviation limit set in step (2), the temperature compensation coefficient of each point in the width direction can be calculated according to formula (2);

[0019] If the temperature in the width direction exceeds the deviation limit amplitude set in step (2), the average temperature in the width direction is used to substitute into formula (2) to calculate the temperature compensation coefficient at this point;

[0020] Step (5): Obtaining the cold state thickness value of the strip

[0021] Substitute the temperature compensation coefficient obtained in step (4) into formula (1) to obtain the cold state thickness of each point on the cross-section of the strip.

[0022] In the optimization scheme, the deviation limit amplitude in step (2) is 20°C.

[0023] In the optimization scheme, the correct thickness, crown and wedge values are calculated according to the cold state thickness of the strip in step (5).

[0024] Compared with the prior art, the present invention has the following prominent beneficial effects:

[0025] 1. By innovating the calculation method of the temperature compensation coefficient in the system, the present invention realizes the improvement of the thickness detection accuracy, avoids the influence of abnormal temperature zones on the thickness calculation and detection, and achieves the purpose of accurately measuring the thickness, crown and wedge of the strip;

[0026] 2. The present invention avoids the influence of abnormal thickness on product quality and scrap steel accidents, reduces the proportion of defective products caused by abnormal thickness, improves product quality and production stability, and increases economic benefits. Description of the Drawings

[0027] Figure 1 is a schematic structural diagram of the ray thickness gauge of the present invention.

[0028] Figure 2 is a schematic structural diagram of the pyrometer of the present invention. Detailed Embodiment

[0029] The present invention will be further described below in conjunction with the drawings of the specification and the detailed embodiment.

[0030] The present invention provides a ray thickness gauge and a calculation method for its temperature compensation coefficient. In this embodiment, the ray thickness gauge is installed at the outlet of the finishing mill of the thin slab continuous casting and rolling production line, and is the final thickness detection device for the rolled strip.

[0031] As Figure 1 shown, the ray thickness gauge includes a ray source 1, an ionization chamber 2, a C-frame 3 and a central control unit. The ray source 1 and the ionization chamber 2 are multiple.

[0032] The described radiation source 1 is arranged on the upper arm of the C-shaped frame 3, the ionization chamber 2 is arranged below the lower arm of the C-shaped frame 3, and the strip steel 4 is located between the upper and lower arms of the C-shaped frame 3. The ionization chamber 2 is connected to the central control unit for data. The ionization chamber 2 receives the ionization energy passing through the strip steel. The central control unit is used to display and receive the instructions of the operator, and convert the received signals and perform thickness calculation. The upper arm of the C-shaped frame 3 is also provided with an altimeter connected to the central control unit for data. The altimeter includes a scanning pyrometer 5 and a single-point altimeter 6. The scanning pyrometer 5 is installed at the middle position of the upper arm of the C-shaped frame 3. The central control unit includes a temperature measurement system processor and a temperature measurement control system. In this embodiment, the M-client control system of the thickness gauge is adopted. The dual design of the scanning pyrometer 5 and the single-point altimeter 6 can effectively prevent abnormal deviations, that is, the scanning pyrometer 5 is the main data source, and the single-point altimeter 6 is the verification data source. When there is an obvious deviation in the data of the two at the same measurement point, manual verification is prompted, and the data of the pyrometer is switched to prevent calculation compensation coefficient errors.

[0033] As Figure 2 shown, a gas blowing device 8 with a cooling air pipe 7 is connected below the measurement window of the pyrometer. The purging air port 9 of the gas blowing device 8 is connected to the bottom of the pyrometer through a fixing bolt to prevent the pyrometer detection from being interfered by on-site water vapor and dust.

[0034] The pyrometer housing has a sandwich layer, and there are a water inlet and a water outlet on the sandwich layer for connecting a cooling water pipe 10 to cool the pyrometer body.

[0035] Except for special instructions, the above-mentioned hardware and operation control systems have different specifications and data connection methods due to different models. The specific connection methods and data acquisition, conversion, and processing methods are existing technologies and will not be elaborated here.

[0036] The calculation method of the temperature compensation coefficient of the radiation thickness gauge is as follows:

[0037] Step (1): Obtain the temperature compensation coefficient K

[0038] Let S2 be the hot state thickness value at different temperature values and S1 be the cold state thickness value of the strip steel. Then the formula (1) for the temperature compensation coefficient and the hot and cold state thickness of the strip steel can be expressed as:

[0039] K = (S2 - S1) / S1;

[0040] Take a standard thickness sample plate, heat it to different temperatures (such as 800 °C, 900 °C, 1000 °C, etc.) under laboratory conditions, and then use the radiation thickness gauge to measure the thickness of the standard sample plate under the condition of canceling temperature compensation, obtain the compensation coefficients at different temperatures, and fit them with the temperature values into a sixth-degree polynomial curve to obtain the expression formula (2) of the temperature compensation coefficient and temperature:

[0041] K = 1.082e -18 *t 6 - 4.054e -15 *t 5 + 6e -12 *t 4 - 3.065e -9 *t 3 - 1e -6 *t 2 + 0.0015t + 0.596

[0042] Wherein, e is a real number, and in this embodiment, this formula can also be written as:

[0043] K = 1.082 * 10 -18 *t 6 - 4.054 * 10 -15 *t 5 + 6 * 10 -12 *t 4 - 3.065 * 10 -9 *t 3 - 1 * 10 -6 *t 2 + 0.0015t + 0.596

[0044] Write Formula (1) and Formula (2) into the temperature compensation program of the thickness gauge control system.

[0045] Step (2): Set the deviation limit amplitude

[0046] Set the temperature deviation limit amplitude in the width direction in the temperature compensation program of the thickness gauge control system to prevent incorrect thickness value calculation caused by abnormal temperature detection at a certain point;

[0047] In this embodiment, the deviation limit amplitude is 20 °C.

[0048] Step (3): Obtain the digital temperature signal

[0049] The pyrometer measures the surface radiant heat energy in the width direction of the strip steel. The measurement signal is transmitted to the temperature measurement system processor through a serial cable, and the measured temperature value is amplified and A / D converted, and the digital temperature signal is transmitted to the temperature measurement control system by means of serial port or Ethernet, etc.

[0050] Step (4): Temperature compensation

[0051] Connect the temperature data of each point in the cross-section collected in Step (3) to the temperature compensation program of the thickness gauge control system in Step (1);

[0052] If the temperature in the width direction does not exceed the deviation limit amplitude set in step (2), the temperature compensation coefficients at each point in the width direction can be calculated according to formula (2).

[0053] If the temperature in the width direction exceeds the deviation limit amplitude set in step (2), the average temperature in the width direction is used to substitute into formula (2) to calculate the temperature compensation coefficient at this point.

[0054] Step (5): Obtaining the cold state thickness value of the strip

[0055] Substitute the temperature compensation coefficient obtained in step (4) into the strip thickness in the cold state at each point on the cross-section obtained by using formula (1), and then obtain the correct thickness, crown and wedge values.

[0056] In the optimization scheme, the deviation limit amplitude of the temperatures of the scanning pyrometer 5 and the single-point altimeter 6 at the same temperature measurement point is also set in step (2), and if the deviation limit amplitude of the temperatures at the same point exceeds the limit, an alarm prompt is triggered, and the operator manually checks the pyrometer data and switches the data substitution in step (4).

[0057] It should be noted that the specific embodiments of the present invention have been described in detail. For those skilled in the art, various obvious changes made without departing from the spirit and scope of the present invention are within the protection scope of the present invention.

Claims

1. A method for calculating the temperature compensation coefficient of a ray thickness gauge, characterized in that: It includes the following steps: Step (1): Obtain the temperature compensation coefficient K Let S2 be the hot state thickness value at different temperature values, and S1 be the cold state thickness value of the strip. Then, the formula (1) for the temperature compensation coefficient and the hot and cold state thickness of the strip can be expressed as: K = (S2 - S1) / S1; Take a standard thickness sample plate, heat it to different temperatures under laboratory conditions, measure the thickness of the standard sample plate using a ray thickness gauge under the condition of canceling temperature compensation, obtain the compensation coefficients at different temperatures, fit them with the temperature values into a sixth-degree polynomial curve, and obtain the expression formula (2) for the temperature compensation coefficient and temperature: K = 1.082e -18 *t 6 -4.054e -15 *t 5 +6e -12 *t 4 -3.065e -9 *t 3 -1e -6 *t 2 +0.0015t + 0.596 Write formula (1) and formula (2) into the temperature compensation program of the thickness gauge control system; Step (2): Set the deviation limit amplitude Set the deviation limit amplitude in the temperature compensation program of the thickness gauge control system; set the temperature deviation limit amplitude of the scanning pyrometer and the single-point altimeter at the same temperature measurement point. When the temperature deviation limit amplitude at the same point exceeds the limit, an alarm prompt is triggered, and manual data verification of the scanning pyrometer and the single-point altimeter and data substitution and switching in step (4) are performed; Step (3): Obtain the digital temperature signal The scanning pyrometer measures the surface radiant heat energy in the width direction of the strip. The measurement signal is transmitted to the temperature measurement system processor, and the measured temperature value is amplified and A / D converted, and the digital temperature signal is transmitted to the temperature measurement control system; Step (4): Temperature compensation Connect the temperature data of each point in the cross-section collected in step (3) to the temperature compensation program of the thickness gauge control system in step (1); If the temperature in the width direction does not exceed the deviation limit amplitude set in step (2), the temperature compensation coefficient of each point in the width direction can be calculated according to formula (2); If the temperature in the width direction exceeds the deviation limit amplitude set in step (2), the average temperature in the width direction is substituted into formula (2) to calculate the temperature compensation coefficient of this point; Step (5): Obtain the cold state thickness value of the strip Substitute the temperature compensation coefficient obtained in step (4) into the formula (1) to obtain the cold state thickness of the strip at each point in the cross-section.

2. The method for calculating the temperature compensation coefficient of the ray thickness gauge according to claim 1, wherein: The deviation limit amplitude in step (2) is 20°C.

3. The method for calculating the temperature compensation coefficient of the ray thickness gauge according to claim 1, characterized in that: Calculate the correct thickness, crown, and wedge values according to the cold state thickness of the strip in step (5).

4. The method for calculating the temperature compensation coefficient of the ray thickness gauge according to claim 1, characterized in that: The scanning pyrometer and the single-point altimeter are located on the upper arm of the C-frame of the radiation thickness gauge, and the scanning pyrometer and the single-point altimeter are data-connected to the central control unit.

5. The method for calculating the temperature compensation coefficient of the ray thickness gauge according to claim 4, wherein: The scanning pyrometer is located at the middle position of the upper arm of the C-frame of the radiation thickness gauge.

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