JPS63133211A - Temperature control method for treating product - Google Patents

Abstract

PURPOSE:To properly control the temperature of a treating product by detecting the passing time interval of the treating product to use this as an arithmetic element for both integration and differentiation terms. CONSTITUTION:A radiation thermometer 6 is set at a single side of a carry-in conveyor 4 corresponding to the transport downstream part of a treating conveyor 3 to measure the temperature of a treating product 1 together with a sensor 7 which detects the pass of the product 1. The temperature measurement signal of the product 1 obtained by the thermometer 6 is supplied to a microprocessor 8 together with the pass pulse signal of the product 1 obtained by the sensor 7. Then the processor 8 calculates the correction value DELTAPn by an equation including a 1st proportion term, a 2nd integration term and a 3rd differentiation term. Furthermore, Xn means the latest measured temperature of the product 1 in the equation together with Xn-1 and Xn-2 meaning the measured temperatures of the product 1 passed before a step and two steps, Rn meaning target temperature of the product 1, K meaning the proportion gain, T1 meaning the integration time, TD meaning the differentiation time, and tau meaning the passing time interval of the product 1. The value DELTAPn is converted by an inverter 9 into a signal that controls a variable speed motor 10 of the conveyor 3 and then supplied to the processor 8.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a method for continuously heat-treating billet-like, block-like processed products, or single-processed products such as automobile parts to a required temperature. This invention relates to a method of controlling the processing temperature by controlling the speed of a conveyor.

[Prior art and problems] Conventionally, in continuous heat treatment equipment in which the processed product is cooled or heated to a target temperature by passing through a heat treatment chamber such as a cooling chamber or a heating chamber, the transport speed of the processed product has traditionally been controlled. By adjusting the temperature, the residence time of each processed item in the heat treatment chamber is changed to control the processing temperature of the processed item. That is, a thermometer such as a radiation thermometer to measure the temperature of the processed product is installed at an appropriate location near the exit of the heat treatment chamber, and the measured temperature of the processed product at each temperature is compared with the target processing temperature, and the deviation is determined through a controller. There is a known system that automatically controls the temperature of processed products to a target processing temperature by operating the operating speed of a processing conveyor according to the processing speed. However, in the conventional method, the control system does not operate as expected unless the processed product is in a continuous form, such as a strip of material. In other words, 1. For example, when single products such as connecting rods for automobile engines are placed one after another on a processing conveyor at appropriate intervals and then transported and heat-treated, especially if the intervals between the products are irregular. In the conventional method described above, even if sampling (temperature measurement) is performed at regular intervals, the processed product may not be at the temperature measurement position at the time of sampling, and an accurate feedback signal cannot be obtained, so the control system does not work properly. There was a risk that it would not.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a system in which a large number of single-piece processed products are placed on a processing conveyor at appropriate intervals and transported one after another, and during the transport, the In a device that cools or heats the processed product, a thermometer is installed to measure the temperature of the processed product downstream of the processing conveyor, and a sensor is installed to detect the passage of the processed product, and the operating speed of the processing conveyor is determined by the following formula: The present invention aims to provide a method for controlling the temperature of a processed product, which is characterized by performing feedback control using a correction amount ΔPn given by ΔPn.

[Action] The correction amount ΔPn given by this equation is based on the three-term operation (proportional, integral,
(differential) PID control can be performed.

[Example] Next, the present invention will be described in detail with reference to the drawings. In this embodiment, processed products 1゜1... pressed by a forging machine are transferred from a relay conveyor 2 to a processing conveyor 3 for natural air cooling, and are processed while being conveyed on the processing conveyor 3. Item 1,
1. After cooling to the required temperature by natural cooling,
Furthermore, this line transfers the treated products 1.1, . In this line, the operating intervals of the forging machines are not constant, so the processed products 1.1... are not always sent at regular intervals. In other words, the intervals between the processed products 1, 1, . . . on the processing conveyor 3 are random.

Therefore, a radiation thermometer 6 for measuring the temperature of the processed products 1, 1, etc. is provided on one side of the charging conveyor 4, which is downstream of the processing conveyor 3. A sensor 7 is provided to detect the passage of... The temperature signal measured by the thermometer 6 and the pulse No. 43 obtained from the sensor 7 are input to the microprocessor 8 which performs a PID calculation. Then, the microprocessor 8 calculates the following correction amount ΔPn.

-Xn-2) is a differential term.

The formula (■) giving this ΔPn is known as a control formula for the idealized three-term operation of an analog controller (To: differential time j) The differential PID control formula derived from this formula is Pn=KCLen +Σ- Th
en-1-P-(en en-+) becomes .■. To convert this into a velocity form that gives the correction amount ΔPn for the position of the operating end, differentiate the above equation (■) and calculate -2en-+
+en-z)・・・・・・・・・■In this formula, err
= Rn −Xn+ en−+ = Rn −Xn −
By substituting +en -2=Rn -Xn-2, the above formula (2) is derived.

Therefore, the integral term Gelling time in formula (2) used in the present invention, that is, the transit time interval 7 of the processed product, is added as a weighting element to the numerator and denominator, respectively, and the integral term is the time during which the deviation lasted, and the differential term is the deviation change. The time ratio is also calculated each time a processed product passes through. The correction amount ΔPn given by 2〇 is converted into a signal for controlling the variable speed motor 10 of the processing conveyor 3 by the inverter 9, and the operating speed of the processing conveyor 3 is corrected and the processed products 1 on the processing conveyor 3 are controlled. , 1... by controlling the conveyance speed and adjusting the cooling time to automatically control the temperature of the treated products 1, 1... at the downstream part of the conveyance to the target temperature, and then transfer them to the continuous heat treatment furnace 5. The processed product 1 when being charged
．． 1. Keep the temperature constant.

Note that this time 7 is the sensor 7 installed just before the radiation thermometer 6.
However, the sensor does not necessarily have to be in this position as long as it can detect the passage of the processed product.

In this way, the present invention weights the passing time interval of the processed product as an element of the integral term gain and the differential term gain, so even if the sampling period is not constant, the integral term and the differential term will have abnormal values. There is no.

[Effects of the Invention] As described above with respect to the embodiments, the method for controlling the processed product according to the present invention detects the passing time interval of the processed product and uses this as a calculation element for the integral term and the differential term. Even if the passing interval is irregular and temperature measurement sampling cannot be performed at regular intervals, the ideal control characteristics of three-term operation using the proportional, integral, and differential terms are always achieved and the temperature of the processed product can be properly controlled. It is beneficial.

4. The drawing is a temperature control system diagram of a continuous heat treatment apparatus for processed products showing an embodiment of the present invention.

l...Processing product, 3...Processing conveyor, 6...
・Thermometer, 7... Passage detection sensor, 8... Microprocessor, 9... Inverter, lO...
Variable speed motor.

Claims (1)

[Scope of Claims] In an apparatus in which a large number of single products to be processed are placed on a processing conveyor at appropriate intervals and conveyed one after another, and the processed products are cooled or heated during the conveyance, the downstream part of the processing conveyor is A thermometer is provided to measure the temperature of the processed product in the section, and a sensor is provided to detect the passage of the processed product, and the operating speed of the processing conveyor is adjusted by the correction amount ΔPn given by the following equation.
A method for controlling the temperature of a processed product, characterized by feedback control. ΔPn=K(Xn_-_1-Xn)+(K・τ/T_I
)(Rn-Xn)+(K・T_D)/τ(2Xn_-_
1-Xn-Xn_-_2) [However, Xn: Latest measured temperature of processed product
____2; Measured temperature Rn of the processed product that passed two times ago; Target processing temperature K of the processed product; Proportional gain (constant) T_I; Integral time (constant) T_D; Derivative time (constant) τ; Passage of the processed product Time interval〕