JP2007100181A - Continuous heating furnace and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous heating furnace with which in spite of flowing state of a work into the furnace, the work can stably and efficiently be heated. <P>SOLUTION: The continuous heating furnace has the constitution provided with a work sensor 5 for detecting the distributing state of the works W in the furnace 3c, and a total necessary heat-giving amount calculating part 6, in which the necessary heat-giving amount in the respective work W existing in the furnace 3c is obtained based on the distributing state of the detected work W, and the total necessary heat-giving amounts Qt as the total amounts of the obtained necessary heat-giving amounts are calculated. Further, in such the continuous heating furnace, a heater outlet heating amount control part 7 for controlling the outlet heating amount of a heater unit 4 based on the total necessary heat-giving amount Qt calculated by the total necessary heat-giving amount calculating part 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a continuous heating furnace in which a workpiece is heated by passing through a furnace heated by a heater while being conveyed in a certain direction, and a control method thereof.

  For example, as a heating furnace that heats the workpiece for heat treatment such as brazing, quenching, and annealing of parts, the workpiece is continuously heated by passing through the furnace heated by the heater in a certain direction. Continuous heating furnaces are known. Management of the in-furnace temperature of such a continuous heating furnace is normally performed by detecting the in-furnace temperature and feedback controlling the heater output so that the deviation between the preset target temperature and the detected in-furnace temperature is reduced. It has been broken.

In recent years, in order to cope with a large variety of small-quantity production, there are increasing opportunities to heat-treat various types of workpieces continuously in the same continuous heating furnace. Conventionally, a technique described in Patent Document 1 is known as a technique for controlling the temperature in a furnace for suitably performing continuous heating of such various types of workpieces. In the technique described in this document, the optimum furnace temperature is obtained for each of the workpieces existing in the furnace and the work scheduled to be carried into the furnace, and the weighted average value of the optimum temperature of each workpiece is obtained as the target temperature in the furnace. By setting to, the sudden change of the target temperature according to the work loading status is suppressed.
JP-A-9-157760

  By the way, in such a continuous heating furnace, when the carrying interval of the workpiece into the furnace changes greatly, the amount of heat that the atmosphere in the furnace dissipates to the workpiece changes, and the furnace temperature may fluctuate greatly temporarily. In recent years, due to the high-mix low-volume production, there are many opportunities to heat-treat many types of workpieces continuously in the same continuous heating furnace, but when workpieces with different heat capacities flow into the furnace, Again, the amount of heat released to the workpiece in the furnace atmosphere may change, causing fluctuations in the furnace temperature. As a result, there is a risk that excessive or insufficient heating of the workpiece may occur.

  Although the conventional technology described above suppresses sudden changes in the target temperature in consideration of the workpiece before being carried into the furnace, such a change in the workpiece carrying situation can be achieved only by feedback control of the furnace temperature as described above. It is difficult to sufficiently cope with fluctuations in the furnace temperature due to. Therefore, the heat capacity of the furnace itself is increased to suppress fluctuations in the furnace temperature with respect to changes in the inflow condition of the workpiece, the amount of work carried into the furnace is adjusted in advance, or heat treatment is performed in the same continuous heating furnace. It is necessary to stabilize the in-furnace temperature by limiting the type of work to be performed only to those having a similar heat capacity, or suppressing changes in the inflow state of the work.

  However, if the heat capacity of the furnace itself is increased, the equipment cost increases due to the increase in the furnace size and the thermal efficiency deteriorates. In addition, there is a problem in that the production line management becomes complicated in order to perform advance adjustment of the work carry-in amount. Furthermore, if the types of workpieces to be heat-treated in the same continuous heating furnace are limited, a large number of continuous heating furnaces are required, leading to an increase in production facilities.

  The present invention has been made in view of such a situation, and the problem to be solved is a continuous heating furnace capable of stably and efficiently heating regardless of the state of the work flow into the furnace. It is to provide.

  In order to achieve such an object, according to the first aspect of the present invention, as a continuous heating furnace that heats a work while being conveyed in a fixed direction through a furnace heated by a heater, the distribution state of the work in the furnace. Based on the workpiece distribution detecting means for detecting the workpiece and the distribution status of the detected workpiece, the required heating amount is calculated for each workpiece existing in the furnace, and the total required heating amount is obtained as a total requirement. A calculation means for calculating the heat amount and a control means for controlling the output heat amount of the heater based on the calculated total required heat amount are provided.

  According to the above configuration, the workpiece distribution state in the furnace is detected by the workpiece distribution detection unit, and the calculation unit obtains the required heat amount for each of the workpieces in the furnace based on the detected workpiece distribution state, The total required heat amount that is the sum of the required heat amounts is calculated. And a control means controls the output heat amount of a heater based on the total required heat amount calculated in this way. That is, in the above configuration, the amount of heat given to each workpiece in the furnace is obtained from the distribution state of the workpiece in the furnace, and the output heat amount of the heater is controlled accordingly. Therefore, even if the amount of heat released to the workpiece in the furnace atmosphere changes greatly due to the change in the inflow condition of the workpiece into the furnace, the heater output corresponding to the change in the amount of heat released before the furnace temperature fluctuates. Adjustments can be made. For this reason, it becomes possible to stably and efficiently heat each workpiece in the furnace regardless of the state of the workpiece flowing into the furnace. In addition, the heater output heat quantity can be adjusted according to the heat quantity to be supplied to the work in the furnace, and the work can be efficiently heated without excess or deficiency.

In such a continuous heating furnace, as a specific control of the output heat amount of the heater by the control means, for example, according to the invention of claim 2,
(A) Feed forward control of the output heat amount of the heater is performed based on the required heat amount.
Or, according to the invention of claim 3,
(B) A calorific value detecting means for detecting the total heat amount of the workpiece existing in the furnace is further provided, and the output heat amount of the heater is based on a deviation between the detected total heat amount and the total required heat amount. Feedback control.
And so on. Incidentally, according to the feedforward control of (a) above, the output heat amount of the heater can be caused to follow more quickly according to the distribution state of the work in the furnace. On the other hand, according to the feedback control of (b) above, the actual total heat quantity in the furnace supplied by the heater is detected through the heat quantity detection means, and this total heat quantity is fed back, so that the total heat quantity in the furnace is fed back. It is possible to heat the workpiece more accurately, reflecting the above.

  Further, in the continuous heating furnace according to any one of claims 1 to 3, the calculation of the required heat amount by the calculating means is specifically performed in the furnace, for example, according to the invention according to claim 4. The necessary heat supply amount of the work for each position at is determined with reference to a calculation map stored in advance.

  In this case, moreover, according to the invention described in claim 5, if the calculation means has the calculation map for each type of workpiece, more accurate heating can be performed for a variety of workpieces. Will be able to.

  Moreover, in the continuous heating furnace in any one of Claims 1-5, the workpiece | work distribution condition in a furnace is made into the said continuous heating furnace by the said workpiece | work detection means like the invention of Claim 6, for example. It is detected from the passage time of the workpiece at one point on the workpiece conveyance path.

  In this case, as in the invention described in claim 7, if the workpiece distribution detecting means also identifies the type of the workpiece together with the passing time of the workpiece, the workpiece in the furnace This makes it possible to more accurately recognize the distribution state of the workpiece, and consequently, to heat the workpiece in the furnace with higher accuracy.

  Moreover, in the continuous heating furnace in any one of Claims 1-7, in the invention of Claim 8, the said heater is each for every area | region in the said furnace divided into plurality in the conveyance direction of the said workpiece | work. The calculation means calculates the total required heat amount of the workpiece existing in each area for each of the areas, and the control means calculates the output heat amount of the heater in each area for the calculated corresponding area. It was made to control individually based on the total required heating amount.

  The amount of heat of the work necessary for heating varies depending on the position in the furnace. For example, immediately after flowing into the furnace, it is necessary to raise the temperature of the workpiece abruptly, and a large amount of heat is required. On the other hand, when the temperature of the workpiece is increased to a certain extent, a large amount of heat is not required. . In addition, when the distribution of workpieces in the furnace is uneven, a large amount of heat is required for regions with high workpiece density, whereas a large amount of heat is not required for regions with low workpiece density. . In this regard, in the above-described configuration, since the necessary amount of heat is obtained for each region and the output heat amount of the heater is individually controlled, the necessary amount of heat can be individually provided for each region. Therefore, compared with the case where the inside of the furnace is uniformly heated, the heating can be performed efficiently, and the necessary amount of heat can be provided without excess or deficiency so that the workpiece can be heated more appropriately. Also become.

  In the invention according to claim 9, as a method for controlling a continuous heating furnace that heats a workpiece while passing through a furnace heated by a heater in a fixed direction, each of the workpieces existing in the furnace The required amount of heat for changing the temperature in a desired mode is calculated, and the output heat amount of the heater is controlled based on the total required amount of heat that is the sum of the calculated required amounts of heat. .

  According to the above method, the required heating amount is obtained for each of the workpieces in the furnace based on the distribution state of the workpieces in the furnace, and the output heat amount of the heater is calculated based on the total required heating amount which is the sum of the required heating amounts. Be controlled. That is, in the above method, the amount of heat given to each workpiece in the furnace is obtained from the distribution state of the workpiece in the furnace, and the output heat amount of the heater is controlled accordingly. Therefore, even if the amount of heat released to the workpiece in the furnace atmosphere changes greatly due to the change in the inflow condition of the workpiece into the furnace, the heater output corresponding to the change in the amount of heat released before the furnace temperature fluctuates. Adjustments can be made. Therefore, similarly to the first aspect of the invention, each workpiece in the furnace can be stably and efficiently heated regardless of the state of the workpiece flowing into the furnace. In addition, the heater output heat quantity can be adjusted according to the heat quantity to be supplied to the work in the furnace, and the work can be efficiently heated without excess or deficiency.

In this case, the control of the output heat amount of the heater is performed, for example, according to the invention of claim 10,
(C) A method in which the output heat amount is feedforward controlled in accordance with the total required heat amount.
Alternatively, as in the invention according to claim 9,
(D) A method of detecting the total amount of heat of the workpiece existing in the furnace and feedback-controlling the output heat amount of the heater based on a deviation between the detected total amount of heat and the total required amount of heat.
And so on. By the way, according to the feedforward control of the above (c), the output heat quantity of the heater can be followed more rapidly according to the distribution state of the work in the furnace, as in the invention of the second aspect. become. On the other hand, according to the feedback control (d) above, the workpiece can be heated more accurately reflecting the total amount of heat in the furnace, as in the case of the invention according to claim 3.

  Moreover, in the control method of the continuous heating furnace in any one of Claims 9-11, according to the invention of Claim 12, for every area | region in the said furnace divided into plurality in the conveyance direction of the said workpiece | work. The output heat amount of the heater can be individually controlled, and the total required heat amount of the work existing in the region is calculated for each of the regions, and each of the regions based on the calculated total required heat amount of the corresponding region. It is also effective to individually control the output heat amount of the heater in the region. As described above, the amount of heat of the work necessary for heating varies depending on the position in the furnace. In addition, when the distribution of workpieces in the furnace is uneven, a large amount of heat is required for regions with high workpiece density, whereas a large amount of heat is not required for regions with low workpiece density. . In this regard, in the above-described method, a necessary amount of heat is obtained for each region, and the output heat amount of the heater is individually controlled. Therefore, the necessary amount of heat can be individually provided for each region. For this reason, as in the case of the invention described in claim 8, the heating can be performed more efficiently than when the inside of the furnace is uniformly heated, and the necessary amount of heat is supplied without excess or deficiency. Can be heated more appropriately.

(First embodiment)
Hereinafter, a first embodiment of the continuous heating furnace and the control method thereof according to the present invention will be described in detail with reference to FIGS.

  In FIG. 1, the whole structure of the continuous heating furnace of this embodiment is shown. As shown in the figure, a belt conveyor 2 for conveying a work W to be heated is disposed on an upper portion of a base 1 placed on a floor surface, and a box-shaped furnace body 3 is fixed. Yes. The workpiece W is conveyed on the belt conveyor 2 from the left side (hereinafter referred to as a workpiece carry-in side) in the drawing to the right side (described as a workpiece carry-out side) in the drawing. The belt conveyor 2 is installed so as to pass through the furnace interior 3c through a furnace inlet 3a and a furnace outlet 3b formed on the work carry-in side and the work carry-out side of the furnace body 3, respectively.

  A heater unit 4 for heating the inside 3 c of the furnace is disposed on the top of the furnace body 3. The heater unit 4 includes a heat wire 4a that heats the atmosphere in the furnace 3c, and a fan 4b that circulates the atmosphere heated by the heat wire 4a to the furnace 3c.

  A work sensor 5 is provided above the belt conveyor 2 on the work carry-in side of the furnace body 3 to detect whether or not the work W has passed and to identify the type of the work W that passes. For example, the work sensor 5 is irradiated with a sound wave toward the upper surface of the belt conveyor 2, and the reflected wave is received and analyzed to determine whether the work W has passed and to identify the type of the work W. An acoustic sensor to perform is used. From the detection result of the workpiece sensor 5, the workpiece distribution state in the furnace 3c is grasped.

  Information on the work distribution status detected by the work sensor 5 is input to the total required heat amount calculation unit 6 constituting the control system of the continuous heating furnace and is stored in the memory. The stored information is used to calculate the total required heat amount Qt in the total required heat amount calculation unit 6. The calculated total required heat amount Qt is output to the heater output heat amount control unit 7 that also constitutes the control system, and is used for the output heat amount control of the heater unit 4 by the heater output heat amount control unit 7. Actually, the total required heat amount calculation unit 6 and the heater output heat amount control unit 7 are configured to include a microcomputer or the like.

  Next, details of temperature control for adjusting the furnace temperature in the continuous heating furnace configured as described above will be described. In the continuous heating furnace of the present embodiment, the total required heating amount calculation unit 6 calculates the required heating amount Q for each of the workpieces W present in the furnace 3c based on the distribution state of the workpieces W detected by the workpiece sensor 5. The total required heat quantity Qt, which is the sum of the calculated required heat quantities, is calculated. The required heating amount Q here is the heating amount with respect to the workpiece W required to change the temperature of the workpiece W in a desired manner, and the value is calculated by the following equation (1). In the following formula (1), “m” represents the mass of the workpiece W, “c” represents the specific heat of the workpiece W, and “u” represents the heat transfer coefficient of the workpiece W.

また上式（１）における「θ」は、予定温度上昇量であり、炉内３ｃでのワークＷの温度を予定温度プロファイルに従って所望とする態様で推移させるために必要なワークＷの温度上昇量を示している。本実施形態では、上記炉内３ｃにおける炉入口３ａから炉出口３ｂまでのワークＷの搬送経路を上記総必要与熱量Ｑｔの算出周期におけるワークＷの搬送距離ずつ区分けした４つの区間Ｚ１〜Ｚ４の別に、予定温度上昇量θを求めている。すなわち、図２に示すような予定温度プロファイルでワークＷの温度を推移させるときの、各区間Ｚ１〜Ｚ４に位置するワークＷの予定温度上昇量θはそれぞれ、「Θ１」、「Θ２」、「Θ３」、「Θ４」となる。

In addition, “θ” in the above formula (1) is a planned temperature rise amount, and the temperature rise amount of the work W necessary to change the temperature of the work W in the furnace 3c in a desired manner according to the planned temperature profile. Is shown. In the present embodiment, there are four sections Z1 to Z4 obtained by dividing the transfer path of the work W from the furnace inlet 3a to the furnace outlet 3b in the furnace 3c by the transfer distance of the work W in the calculation cycle of the total required heat quantity Qt. Separately, the estimated temperature increase amount θ is obtained. That is, when the temperature of the workpiece W is changed according to the planned temperature profile as shown in FIG. 2, the planned temperature increase amounts θ of the workpieces W located in the sections Z1 to Z4 are “Θ1”, “Θ2”, “ Θ3 ”and“ Θ4 ”.

  Incidentally, in the present embodiment, the required heat quantity Q of the workpiece W existing in the furnace 3c is calculated as follows. That is, the total required heat amount calculation unit 6 is provided with a calculation map as illustrated in FIG. 3 in which the required heat supply amount of the work W for each of the sections Z1 to Z4 in the furnace 3c is stored for each type of work. ing. The total required heat amount calculation unit 6 obtains the necessary heat amount Q (Zi) wj corresponding to the section Zi where the corresponding workpiece W is located and the type Wj of the workpiece W from this calculation map. The amount of heat Q is calculated.

  In addition, the said required heat amount Q becomes large, so that the heat capacity of the workpiece | work W is large, even if it exists in the same area where the said estimated temperature rise amount (theta) is equal. For example, as shown in FIG. 4, when the heat capacity of the work W2 is larger than the heat capacity of the work W1, the necessary heat amounts Q (Z1) w2 to Q (Z4) w2 of the work W2 in the sections Z1 to Z4 are the same. The required heating amount Q (Z1) w1 to Q (Z1) w1 of the workpiece W1 in the sections Z1 to Z4 is larger. The necessary heat quantity Q of the calculation map also reflects information on the type of the work W, and an appropriate value of the required heat quantity Q according to the type of the work W can be referred to.

  The total required heat amount calculation unit 6 calculates the required heat amount Q for each of the workpieces W present in the furnace 3c, and calculates the sum of them as the total required heat amount Qt. Actually, the in-furnace loss Qf of the in-furnace 3c is also added to the total required heat amount Qt. Hereinafter, specific examples of the distribution state of the workpieces W in the furnace 3c are shown in FIGS. 5A to 5C, and the relationship between the distribution status of each workpiece W existing in the furnace 3c and the total required heat amount Qt is shown. explain.

  As shown in FIG. 5A, in the case of a distribution situation in which the workpiece W1 exists in each of the sections Z1 to Z4 of the furnace 3c, the total required heat amount Qt is the required heat amount Q (Z1) w1 + required Heating amount Q (Z2) w1 + required heating amount Q (Z3) w1 + required heating amount Q (Z4) w1 + in-furnace loss Qf. Further, in the case of a distribution situation in which the work W1 exists in each of the sections Z1, Z3, and Z4 excluding the section Z2 in the furnace 3c, the total required heat amount Qt is the required heat amount Q (Z1) w1 + required supply. The amount of heat Q (Z3) w1 + the required amount of heat Q (Z4) w1 + the in-furnace loss Qf is calculated. On the other hand, in a distribution situation where the workpiece W2 exists in the section Z1 of the furnace 3c and the workpiece W1 exists in the sections Z2 to Z4, the total required heat amount Qt is the required heat amount Q (Z1) w2 + the required heat amount Q. (Z2) w1 + required heating amount Q (Z3) w1 + required heating amount Q (Z4) w1 + in-furnace loss Qf. As described above, the total required heat amount Qt is calculated according to the distribution state of the work W present in the furnace 3c.

  The total required heat amount Qt calculated by the total required heat amount calculation unit 6 is input to the heater output heat amount control unit 7. The heater output heat amount control unit 7 controls the output heat amount of the heater unit 4 based on the total necessary heat amount Qt so that the necessary amount of heat is output without excess or deficiency. A specific configuration example of such a control system is shown below.

(Control system configuration example 1)
FIG. 6 shows the configuration of the control system when the heater output heat quantity control unit 7 controls the output heat quantity of the heater unit 4 by feedback control of the total heat quantity Qa. As shown in the figure, in this control system, the total heat amount Qa detected through the heat amount sensor disposed in the furnace 3c is fed back. And the command value of the fan air volume and the heat-wire energization amount of the heater unit 4 such that the deviation between the total required heat amount Qt and the total heat amount Qa input from the total required heat amount calculation unit 6 is reduced. It is output to the heater unit 4 through output feedback control (heater output F / B control). In the heater unit 4, the air volume of the fan 4b and the energization amount to the heat wire 4a are adjusted according to these command values. In the furnace 3c, a part of the output heat amount from the heater unit 4 is consumed as the in-furnace loss Qf, and the remaining heat amount is absorbed by the workpiece W. The heat quantity sensor is configured to detect a total heat quantity Qa, which is a heat quantity obtained by subtracting the in-furnace loss Qf and the heat quantity absorbed by the work W from the output heat quantity.

  An example of the configuration of a heat quantity sensor used in the feedback control system is shown in FIG. As shown in the figure, temperature sensors TC1 and TC2 are disposed on the outlet side and the inlet side of the fan 4b of the heater unit 4, respectively. Thereby, the said total heating amount Qa can be calculated | required from the difference of the air volume of the fan 4b, and the temperature in a furnace detected by the said temperature sensor TC1, TC2. For example, thermocouples can be used as the temperature sensors TC1 and TC2.

  Such feedback control is performed by the heater output heat quantity control unit 7 repeatedly executing the temperature control described below every predetermined time. Hereinafter, the temperature control executed by the heater output heat quantity control unit 7 will be described with reference to the flowchart shown in FIG.

  As shown in the figure, the heater output heat quantity control unit 7 first reads in the loading time and type information of the workpiece W obtained through the workpiece sensor 5 as the processing of step S10. Thereafter, in step S11, the heater output heat quantity control unit 7 derives the in-furnace position of each work W, that is, the section where the work W is located, based on the loading time of the work W. Then, in the subsequent process of step S12, in the heater output heat quantity control unit 7, the required heat quantity Q of each workpiece W existing in the furnace 3c is calculated based on the position of the workpiece W in the furnace and the type information of the workpiece W. Each is calculated from the calculation map. Further, as a process of step S13, the heater output heat amount control unit 7 sets the total required heat amount Q of each workpiece W calculated as the total required heat amount Qt. In actuality, as described above, the total required heat amount Qt is calculated as a value including the in-furnace loss Qf of the in-furnace 3c in the total sum of the required heat amounts Q of the workpiece W.

  Further, as the processing of step S20, the heater output heat amount control unit 7 calculates the total heat amount Qa for the work W in the furnace 3c based on the inlet temperature, the outlet temperature, and the air volume of the fan 4b of the heater unit 4, and the subsequent step S21. It is determined whether or not the calculated total heat amount Qa is larger than the total required heat amount Qt. Here, when it is determined that the total heat amount Qa is larger than the total required heat amount Qt, the air flow amount of the fan 4b and the energization amount of the heat wire 4a are decreased, and then the processing is ended. On the other hand, when it is determined in step S21 that the total heat amount Qa is equal to or less than the total required heat amount Qt, the air flow amount of the fan 4b and the energization amount of the heat wire 4a are increased, and then the process is terminated. .

(Control system configuration example 2)
FIG. 9 shows the configuration of the control system in the case where the heater output heat quantity control unit 7 controls the output heat quantity of the heater unit 4 by feedforward control. As shown in the figure, in this control system, the command value of the fan air volume and the heat ray energization amount of the heater unit 4 based on the total required heat quantity Qt input from the total required heat quantity calculation unit 6 is set as the heater output. It is output to the heater unit 4 through feedforward control (heater output F / F control). In the heater unit 4, the air volume of the fan 4b and the energization amount to the heat wire 4a are adjusted according to the command value.

  In addition, the fan air volume and the heat ray energization amount of the heater unit 4 are obtained based on the relationship between the total required heat amount Qt, the heat ray energization amount, and the fan air amount as shown in FIG. 10, for example. The relationship between the total required heat amount Qt, the heat-wire energization amount, and the fan air volume is obtained in advance through experiments and simulations and is stored in the heater output heat amount control unit 7.

(Control system configuration example 3)
In addition to this, as shown in FIG. 11, a control system combining the feedback control and the feedforward control is also effective as the control system configuration. Here, when PID control is adopted as the heater output feedback control, the operation amount for controlling the heater output heat amount, that is, the energization amount of the heat wire 4a of the heater unit 4 and the command value of the air amount of the fan 4b are proportional gains. When the deviation between Kp and the target temperature in the furnace and the temperature in the furnace is ΔT, the following equation (2) is obtained. In the following equation (2), the first to third terms on the right side are feedback terms, more specifically, the first term is a proportional term, the second term is an integral term, and the third term is a differential term. The fourth term is a feed forward term.

なお、こうした本実施の形態では、ワークセンサ５がワーク分布検出手段に、総必要与熱量算出部６が算出手段に、ヒータ出力熱量制御部７が制御手段にそれぞれ相当する構成となっている。更に、温度センサＴＣ１，ＴＣ２が熱量検出手段に相当する構成となっている。

In this embodiment, the work sensor 5 corresponds to the work distribution detection means, the total required heat amount calculation section 6 corresponds to the calculation means, and the heater output heat amount control section 7 corresponds to the control means. Furthermore, the temperature sensors TC1 and TC2 are configured to correspond to a heat quantity detection means.

According to the continuous heating furnace and its control method according to the present embodiment described above, the following effects can be obtained.
(1) The inside 3c of the furnace is divided into four sections Z1 to Z4 in the conveyance direction of the workpiece W, and the total required heating amount calculation unit 6 requires the workpiece W existing in the section for each of the sections Z1 to Z4. The total required heat quantity Qt as the sum total was calculated from the heat quantity Q. Further, the heater output heat quantity control unit 7 adjusts the air volume of the fan 4b and the energization quantity of the heat wire 4a in the heater unit 4 based on the calculated total required heat quantity Qt. For this reason, even if the amount of heat released to the workpiece W in the furnace atmosphere changes greatly due to a change in the inflow state of the workpiece W into the furnace 3c, it responds to the change in the amount of heat released before the temperature in the furnace changes Thus, the air volume of the fan 4b and the energization amount of the heat wire 4a in the heater unit 4 can be adjusted. Therefore, it becomes possible to stably and efficiently heat each workpiece W in the furnace 3c regardless of the state of the work flow into the furnace 3c. In addition, since a necessary amount of heat is obtained for each of the sections Z1 to Z4 and the output heat amount of the heater unit 4 is controlled, a necessary amount of heat can be provided for each of the sections Z1 to Z4. Therefore, as compared with the case where the furnace 3c is uniformly heated, the heating can be performed efficiently, and the work W can be heated more appropriately by supplying the necessary amount of heat without excess or deficiency. It becomes like. This eliminates the need to increase the heat capacity of the furnace body 3 itself according to the maximum load of the furnace body 3 as in the prior art, and it is also possible to reduce the size of the furnace body 3 and suppress power consumption in the continuous heating furnace. become able to.

  (2) Since the type of the workpiece W carried into the furnace body 3 is also identified through the workpiece sensor 5, not only the same type of workpiece W but also various types of workpieces W are heated more accurately. Will be able to.

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to FIG.
In the continuous heating furnace according to the present embodiment, a heater unit is provided for each of the regions in the furnace 3c that are divided into a plurality of parts in the conveyance direction of the workpiece W. The continuous heating furnace individually calculates the total required heat amount of the workpiece W existing in each region for each of these regions, and the output heat amount of the heater unit in each region is calculated for each of the calculated regions. It is configured to individually control based on the total required heat amount. In the present embodiment, members having structures and functions similar to or similar to those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 12, in the continuous heating furnace according to the present embodiment, the inside 3 c of the furnace is divided into two regions, an inlet side region Rin and an outlet side region Rout in the workpiece W conveyance direction. In these regions Rin and Rout, individual heater units 4in and 4out are provided, respectively. In addition, individual heater output heat quantity control units 7in and 7out are provided corresponding to the regions Rin and Rout, respectively.

  The total required heat amount calculation unit 6 individually calculates the total required heat amounts Qin and Qout of the workpiece W existing in each region for each of the regions Rin and Rout. The calculation of the total required heat amount Qin, Qout of the workpiece W existing in each of the regions Rin, Rout is performed according to the previous first embodiment. The total required heat amount Qin in the region Rin is input to the heater output heat amount control unit 7in, and the total required heat amount Qout in the region Rout is input to the heater output heat amount control unit 7out.

  Each of the heater output heat amount control units 7in and 7out individually controls the output heat amounts of the corresponding heater units 4in and 4out based on the total required heat amounts Qin and Qout of the corresponding regions Rin and Rout respectively input. That is, the heater output heat amount control unit 7in obtains the command value of the fan air flow rate and the heat ray energization amount from the total required heat amount Qin calculated based on the distribution state of the workpiece W existing in the region Rin, and the heater unit 4in is determined accordingly. Control. Further, the heater output heat quantity control unit 7out similarly obtains a command value for the fan air volume and the heat ray energization quantity from the total required heat quantity Qout calculated based on the distribution state of the workpiece W existing in the region Rout, and the heater is accordingly determined. Control unit 4out.

  In addition, the heater output heat quantity control unit 7out of the present embodiment cancels the excess and deficiency of the heating generated for the workpiece W existing in the region Rin in the region Rout that is a region on the subsequent conveyance path. I have to. Specifically, the total required heat amount calculation unit 6 obtains the total heat amount Qa in the furnace 3c through the heat amount sensor, and the deviation between the total heat amount Qa and the total required heat amount Qin with respect to the work W in the region Rin. Find the excess and deficiency of heating. When the total required heat amount calculation unit 6 recognizes that the workpiece W exists in the region Rout, the deviation is added to the total required heat amount Qout obtained based on the distribution state of the workpiece W existing in the region Rout. A value obtained by adding or subtracting the minute is output to the heater output heat quantity control unit 7out. Thereby, the excess and deficiency of the heating with respect to the workpiece | work W which generate | occur | produced in area | region Rin will be absorbed in area | region Rout. For this reason, the required amount of heat can be more reliably applied to the workpiece W carried into the continuous heating furnace.

According to the continuous heating furnace and the control method thereof according to the present embodiment described above, the following new effects can be obtained.
(3) The inside 3c of the furnace is divided into two regions, an inlet-side region Rin and an outlet-side region Rout, in the conveyance direction of the workpiece W, and individual heater units 4in and 4out are provided in these regions Rin and Rout, respectively. In addition, individual heater output heat quantity control units 7in and 7out are provided corresponding to these regions Rin and Rout, respectively. And about each of these area | regions Rin and Rout, while calculating the total required heat amount Qin and Qout of the workpiece | work W which exists in the area | region separately, respectively the output calorie | heat amount of the heater unit of each area | region is each calculated said area It was made to control separately based on the total required heating amount Qin, Qout of the. For this reason, the heater output calorie | heat amount control part 7out can eliminate the excess and deficiency of the heating which generate | occur | produced with respect to the workpiece | work W which exists in area | region Rin in area | region Rout which is an area | region on a subsequent conveyance path | route. Thus, the required amount of heat can be more reliably given to the workpiece W carried into the continuous heating furnace.

  Note that the continuous heating furnace and the control method thereof according to the present invention are not limited to the above-described embodiments, and can be implemented as, for example, the following forms obtained by appropriately changing the embodiments.

  In the first embodiment, the furnace interior 3c is divided into four sections Z1 to Z4 in the conveyance direction of the workpiece W. However, the number of divisions is not limited to four, and the furnace interior 3c may be divided into an arbitrary number. Moreover, the structure which the furnace 3c becomes one area may be sufficient.

  In the second embodiment, the total required heat amount calculation unit 6 calculates the total required heat amount Qt for each of the regions Rin and Rout, and when excessive or insufficient heating occurs for the work W in the region Rin, By adding or subtracting this excess / deficiency to the total required heat amount Qt in the region Rout, the excess / deficiency of heating of the workpiece W in the region Rin is absorbed. In addition to this, as a method of absorbing the excess and deficiency of heating with respect to the workpiece W, the total required heat amount to be given to the workpiece W is obtained through each region Rin, Rout, and given to the workpiece W in the region Rin. A heat amount obtained by subtracting the total heat amount Qa from the total required heat amount may be set as the total required heat amount Qout. Even in this case, the excess and deficiency of heating of the workpiece W in the region Rin is suitably absorbed in the region Rout which is the subsequent region.

  -In the said 2nd Embodiment, when the excess and deficiency of a heating generate | occur | produces with respect to the workpiece | work W of area | region Rin, this excess / deficiency part is eliminated in area | region Rout. However, when it is not necessary to eliminate the excess and deficiency of heating for the workpiece W in the region Rin as described above, the calculation regarding the excess and deficiency of heating for the workpiece W in the total required heat amount calculation unit 6 is omitted. Also good.

  In the second embodiment, the inside 3c of the furnace is divided into two regions, the region Rin on the inlet side and the region Rout on the outlet side, in the conveyance direction of the workpiece W. However, the number of divisions is not limited to two, and an arbitrary number can be selected.

  In each of the above embodiments, the required heat quantity Q of the workpiece W is calculated based on the calculation map. However, the method for obtaining the required heating amount Q is not limited to the method using the calculation map. For example, the temperature profile for the workpiece W is stored in advance in the total required heating amount calculation unit 6 as an arithmetic expression, and the total required heating amount calculation unit 6 substitutes the position of the workpiece W existing in the furnace 3c into the above arithmetic expression. Then, the estimated temperature increase amount θ is calculated. The total required heat amount calculation unit 6 stores in advance physical property values such as the mass m of the workpiece W, the specific heat c, the heat transfer coefficient u, or their multiplication value (m × c × u) for each type of the workpiece W. Thus, when calculating the required heat quantity Q, the physical property values of the corresponding type of workpiece W are read out. Then, the calculated required temperature rise Q of each workpiece W is calculated by substituting the calculated expected temperature increase amount θ and the read physical property value into the above equation (1). Even if it does in this way, calculation of the total required heat amount Qt can be performed similarly to the said embodiment.

The type of the work W may be identified through reading of identification information registered in an IC tag, a barcode or the like attached to each work W.
In each of the above embodiments, the type of the workpiece W is also identified by the workpiece sensor 5 in order to grasp the distribution state of the workpiece W existing in the furnace 3c. However, in a production mode in which the same type of workpiece W flows continuously, such type information of the workpiece W is not necessarily required, and the acquisition of the type information by the workpiece sensor 5 may be omitted.

The schematic diagram which shows the schematic structure about 1st Embodiment of the continuous heating furnace concerning this invention. The graph which shows the relationship between the workpiece | work position in a furnace, and a workpiece | work temperature. The table | surface which shows an example of the calculation map which the total heating requirement calculation part of the continuous heating furnace concerning the embodiment has. The graph which compares and displays the transition of the required heat amount in each section in the furnace, using two works with different heat capacities as an example. (A), (b), (c) is a schematic diagram which shows the relationship between an example of the distribution condition of the workpiece | work which exists in a furnace, and total required heat amount. The block diagram which shows an example of the control system used when controlling the output calorie | heat amount of a heater unit in the continuous heating furnace concerning the embodiment. The elements on larger scale near the heater unit. The flowchart which shows the process sequence about the temperature control which the heater output calorie | heat amount control part of the continuous heating furnace concerning the embodiment performs. The block diagram which shows an example of the control system used when controlling the output calorie | heat amount of a heater unit in the continuous heating furnace concerning the embodiment. The graph which shows the relationship between a total required heat amount, a fan air volume, and a heat ray energization amount. The block diagram which shows an example of the control system used when controlling the output calorie | heat amount of a heater unit in the continuous heating furnace concerning the embodiment. The schematic diagram which shows the schematic structure about 2nd Embodiment of the continuous heating furnace concerning this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Belt conveyor, 3 ... Furnace main body, 3a ... Furnace inlet, 3b ... Furnace outlet, 3c ... In-furnace, 4, 4in, 4out ... Heater unit, 4a ... Hot wire, 4b ... Fan, 5 ... Work sensor , 6... Total required heat amount calculation unit, 7, 7 in, 7 out... Heater output heat amount control unit, TC1, TC2.

Claims (12)

In a continuous heating furnace that heats the workpiece by passing it through the furnace heated by the heater in a certain direction,
Workpiece distribution detection means for detecting the distribution of workpieces in the furnace;
Based on the detected distribution state of the workpieces, a calculation means for calculating a required heating amount for each of the workpieces present in the furnace and calculating a total required heating amount that is a sum of the required heating amounts,
Control means for controlling the output heat amount of the heater based on the calculated total required heat amount;
A continuous heating furnace comprising: The continuous heating furnace according to claim 1, wherein the control unit performs feedforward control on the output heat amount of the heater based on the required heat amount. In the continuous heating furnace according to claim 1,
And further comprising a calorific value detecting means for detecting the total amount of heat of the workpiece existing in the furnace,
The said control means feedback-controls the output heat amount of the said heater based on the deviation of the detected total heat amount and the said total required heat amount. The continuous heating furnace characterized by the above-mentioned. The continuous heating furnace according to claim 1, wherein the calculation means calculates the required heat amount with reference to a calculation map in which a required heat supply amount of a work for each position in the furnace is stored in advance. The continuous heating furnace according to claim 4, wherein the calculation unit has the calculation map for each type of workpiece. The continuous heating furnace according to any one of claims 1 to 5, wherein the workpiece distribution detecting means detects the distribution status from a passing time of the workpiece at one point on a workpiece conveyance path to the continuous heating furnace. The continuous heating furnace according to claim 6, wherein the workpiece distribution detection means identifies the type of the workpiece together with the passage time of the workpiece. The heater is provided for each region in the furnace divided into a plurality in the workpiece conveyance direction,
The calculation means calculates the total required heat amount of the work existing in the area for each of the areas,
The said control means controls each output heat amount of the heater of each area | region separately based on the calculated total required heat amount of the said applicable area | region, The any one of Claims 1-7 characterized by the above-mentioned. Continuous heating furnace. In a control method of a continuous heating furnace that heats a workpiece by passing through a furnace heated by a heater while passing in a certain direction,
For each of the workpieces present in the furnace, the required heat amount for changing the temperature in a desired manner is calculated, and based on the total required heat amount that is the sum of the calculated required heat amounts A control method for a continuous heating furnace, characterized in that the output heat amount of the heater is controlled. The method for controlling the continuous heating furnace according to claim 9, wherein the control of the output heat amount is performed by feedforward control of the output heat amount according to the total required heat amount. The output heat amount is controlled by detecting the total heat amount of the work existing in the furnace and feedback control of the output heat amount of the heater based on a deviation between the detected total heat amount and the total required heat amount. The method for controlling a continuous heating furnace according to claim 9, wherein the control method is performed. While making it possible to individually control the output heat amount of the heater for each region in the furnace divided into a plurality in the conveyance direction of the workpiece,
Calculating the total required heat amount of the work existing in the region for each of the regions, and individually controlling the output heat amount of the heater in each region based on the calculated total required heat amount of the corresponding region. The method for controlling a continuous heating furnace according to any one of claims 9 to 11, wherein the method is a control method.

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