JP2018094499A - Coating and drying device and coating and drying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve safety of a coating and drying device and a coating and drying method.SOLUTION: A coating and drying device, which coats and dries a steel strip while continuously conveying, includes a conveying part which continuously conveys the steel strip, a coating part which applies paint containing an organic solvent and coats the conveyed steel strip, an oven which dries and bakes the steel strip in a heating space on a downstream side than a coating position, an exhaust part which exhausts the heating space, a concentration measuring part which measures an organic solvent concentration of the organic solvent in the heating space, and a control part which controls operation of the coating and drying device. The control part calculates an arrival predicted concentration based on the organic solvent concentration measured by the concentration measuring part, and controls to stop coating by the coating part while continuing conveyance by the conveying part when the arrival predicted concentration is equal to or higher than a predetermined threshold concentration.SELECTED DRAWING: Figure 4C

Description

  The present disclosure relates to a coating / drying apparatus and a coating / drying method for performing a coating and drying process while continuously conveying a steel strip.

  Conventionally, as a device for coating a steel strip (metal strip) with a roll coater, there has been proposed a coating drying device and method for drying and baking the paint applied to the steel strip in an oven while transporting the steel strip. (For example, see Patent Documents 1-3).

  In the paint drying apparatus of Patent Documents 1-3, the oven is constantly exhausted with a blower by a blower, the temperature of the steel strip entering the oven rises as it enters the back, and the applied paint is dried. . In the middle of the oven, the entire amount of paint dries and enters the baking process.

JP-A-4-193371 JP 2005-262132 A JP-A-8-38855

  However, in the paint drying apparatus as disclosed in Patent Documents 1 and 2, the paint applied to the steel strip usually contains a flammable organic solvent, and the atmosphere in the oven has an evaporated organic solvent. The solvent is diffused. In order to prevent the components of the organic solvent from being ignited by the heat in the oven, it is desirable to maintain the concentration of the organic solvent in the atmosphere in the oven below a predetermined concentration, and by realizing such control with high accuracy. Development of technology that can improve safety and realize energy saving by optimizing the displacement is required.

  However, in actual operation, due to human error when operating the paint drying device or failure of the control device that controls the coating amount, the coating amount is erroneously doubled or excessively increased from the start of operation. May end up. In such a case, an atmosphere with a high organic solvent concentration may not be exhausted and an explosion may occur.

  On the other hand, there is a technique such as Patent Document 3 that increases the displacement based on the organic solvent concentration in the oven. However, a large blower is required to quickly exhaust the atmosphere having an excessive organic solvent concentration. This increases the production cost and requires a large installation space.

  The present disclosure is to solve the above-described problems, and an object thereof is to improve safety in a coating drying apparatus and a coating drying method, and to realize energy saving during operation.

  The coating drying apparatus according to an aspect of the present disclosure is a coating drying apparatus that performs coating and drying treatment while continuously conveying a steel strip, with respect to the transporting section that transports the steel strip, and the steel strip being transported A coating part for applying a paint containing an organic solvent at a coating position, an oven for forming a heating space for drying the steel strip downstream of the coating position, and exhausting the heating space An exhaust unit, a concentration measuring unit that measures the organic solvent concentration of the organic solvent in the heating space, and a control unit that controls the operation of the paint drying apparatus, and the control unit includes the concentration measuring unit Based on the measured concentration of the organic solvent, the predicted predicted concentration is calculated, and when the predicted predicted concentration is equal to or higher than a predetermined threshold concentration, the coating unit stops coating while continuing the transport by the transport unit. Control , It is a paint-drying apparatus.

  According to the above configuration, it is possible to control the concentration of the organic solvent in the heating space from being excessively high, and it is possible to accurately prevent the organic solvent from being ignited by the heat in the heating space. Can be improved.

  In the paint drying apparatus, the control unit may control to slow down the conveyance speed by the conveyance unit in addition to stopping painting by the coating unit when the predicted arrival density is equal to or higher than the threshold concentration. Good. Thereby, the raise of the density | concentration of an organic solvent can further be suppressed, and safety | security can be improved further.

  The paint drying apparatus further includes a removal unit that removes the paint applied to the steel strip by the coating unit on the upstream side of the heating space, and the control unit has the predicted predicted concentration equal to or higher than the threshold concentration. In this case, in addition to stopping the coating by the coating unit, the removal unit may be controlled to remove the paint. Thereby, the raise of the density | concentration of an organic solvent can further be suppressed, and safety | security can be improved further.

  In the paint drying apparatus, the control unit controls to stop the painting by the coating unit while maintaining the same exhaust amount by the exhaust unit when the predicted concentration reaches or exceeds the threshold concentration. May be. Thereby, it can implement as simple control and a mechanism.

  The coating drying method according to one aspect of the present disclosure is a coating drying method in which a steel strip is coated and continuously dried while being transported, and the step of transporting the steel strip and the steel strip being transported A coating step of applying a paint containing an organic solvent at a coating position; a drying step of drying the steel strip in a heating space downstream of the coating position; an exhausting step of exhausting the heating space; A measurement step of measuring the organic solvent concentration of the organic solvent in the heating space, a calculation step of calculating a predicted predicted concentration based on the measured organic solvent concentration, and the predicted predicted concentration being equal to or higher than a predetermined threshold concentration And a coating stopping step of stopping the coating while continuing the conveyance of the steel strip.

  According to the above configuration, it is possible to control to prevent the concentration of the organic solvent in the heating space from becoming excessively high, and to improve safety such as reliably preventing the organic solvent from being ignited by the heat in the heating space. be able to.

  In the coating and drying method, the coating stopping step may include a step of slowing the conveying speed of the steel strip in addition to stopping the coating when the predicted arrival concentration is equal to or higher than the threshold concentration. Thereby, the raise of the density | concentration of an organic solvent can further be suppressed, and safety | security can be improved further.

  In the paint drying method, in the paint stop step, the paint applied to the steel strip at the paint position is added to the heating space in addition to the stop of the paint when the predicted predicted concentration is equal to or higher than the threshold concentration. It may include a step of removing upstream. Thereby, the raise of the density | concentration of an organic solvent can further be suppressed, and safety | security can be improved further.

  In the paint drying method, the paint stop step may stop the paint while maintaining the same exhaust amount when the predicted concentration reaches or exceeds the threshold concentration. Thereby, it can implement as simple control.

  According to the present disclosure, safety can be improved.

The figure which shows schematic structure of the coating drying apparatus in Embodiment 1. Schematic explaining an example of the operation state of the paint drying apparatus in Embodiment 1. Schematic explaining an example of the operation state of the paint drying apparatus in Embodiment 1. Schematic explaining an example of the operation state of the paint drying apparatus in Embodiment 1. Schematic explaining an example of the operation state of the paint drying apparatus in Embodiment 1. The figure which shows an example of the density | concentration change of the organic solvent by the driving | operation of the coating drying apparatus in Embodiment 1. Schematic explaining another example of the operating state of the paint drying apparatus in the first embodiment Schematic explaining another example of the operating state of the paint drying apparatus in the first embodiment Schematic explaining another example of the operating state of the paint drying apparatus in the first embodiment Schematic explaining another example of the operating state of the paint drying apparatus in the first embodiment The figure which shows another example of the density | concentration change of the organic solvent by the driving | operation of the coating drying apparatus in Embodiment 1. Schematic explaining an example of the driving | running state of the coating drying apparatus in Embodiment 2. FIG. Schematic explaining an example of the driving | running state of the coating drying apparatus in Embodiment 2. FIG. Schematic explaining an example of the driving | running state of the coating drying apparatus in Embodiment 2. FIG. Schematic explaining an example of the driving | running state of the coating drying apparatus in Embodiment 2. FIG. The figure which shows an example of the density | concentration change of the organic solvent by the driving | operation of the coating-drying apparatus in Embodiment 2. Schematic explaining an example of the driving | running state of the coating drying apparatus in Embodiment 3. FIG. Schematic explaining an example of the driving | running state of the coating drying apparatus in Embodiment 3. FIG. Schematic explaining an example of the driving | running state of the coating drying apparatus in Embodiment 3. FIG. Schematic explaining an example of the driving | running state of the coating drying apparatus in Embodiment 3. FIG. The figure which shows an example of the density | concentration change of the organic solvent by the driving | operation of the coating drying apparatus in Embodiment 3. The figure which shows an example of the concentration change of the organic solvent when conveyance is stopped in addition to the stop of painting

  Hereinafter, preferred embodiments of a paint drying apparatus and a paint drying method according to the present disclosure will be described with reference to the accompanying drawings. The present disclosure is not limited to the specific configurations of the following embodiments, and configurations based on the same technical idea are included in the present disclosure.

(Embodiment 1)
FIG. 1 is a diagram illustrating a schematic configuration of a coating drying apparatus 2 according to the first embodiment.

  The coating and drying apparatus 2 is an apparatus that performs coating and drying and baking processes while continuously conveying the steel strip S. As shown in FIG. 1, the coating drying apparatus 2 includes a transport unit 4, a coating unit 6, an oven 8, an exhaust unit 10, a concentration measuring unit 12, and a control unit 14.

  The coating drying apparatus 2 applies a paint containing an organic solvent at the coating position 7 by the coating unit 6 (for example, a thickness of about 50 μm) while continuously conveying the steel strip S by the transport unit 4. Thereafter, the steel strip S is heated in the heating space 9 in the oven 8 on the downstream side of the coating position 7, thereby drying and baking the paint applied to the steel strip S.

  In particular, the invention of the present disclosure measures the concentration of the organic solvent in the atmosphere in the heating space 9 by the concentration measuring unit 12 connected to the heating space 9 in the oven 8, and is predicted to reach after that based on the measured concentration. The “arrival predicted density” as the density to be calculated is calculated. Further, when the predicted arrival concentration is equal to or higher than a predetermined threshold concentration, control is performed so as to stop the coating by the coating unit 6 while continuing the transport of the steel strip S by the transport unit 4.

  Hereinafter, each component of the paint drying apparatus 2 will be described.

  The conveyance unit 4 is a mechanism that continuously conveys the steel strip S to the downstream side at a constant speed. The conveyance part 4 shown in FIG. 1 is comprised by the some rotating roll. For example, the steel strip S is unwound from a coil material (not shown) obtained by winding a metal strip thinly stretched into a strip shape in the manufacturing process of the steel plate into a donut shape, and is supplied to the transport unit 4.

  The coating unit 6 is a member that applies paint at the coating position 7 to the steel strip S that is being transported by the transport unit 4. As the paint applied by the coating unit 6, a paint containing an organic solvent such as toluene or xylene is used. As shown in FIG. 1, the painting position 7 by the painting unit 6 is upstream of the oven 8.

  The coating unit 6 shown in FIG. 1 is composed of a roll coater having two rotating rolls. Specifically, the coating unit 6 includes a pick-up roll 6a and an applicator roll 6b as two rotating rolls, and further includes a paint storage unit 6c and a moving mechanism 6d. The pick-up roll 6a is a rotating roll that lifts the paint stored in the paint storage section 6c and contacts the applicator roll 6b to supply or transfer it. The applicator roll 6b is a rotating roll that comes into contact with the steel strip S so that the paint supplied from the pickup roll 6a is applied to the surface of the steel strip S. The paint reservoir 6c is a member (for example, a container) that stores paint. The moving mechanism 6d is a member (for example, a hydraulic cylinder) that can integrally drive the pickup roll 6a, the applicator roll 6b, and the paint reservoir 6c.

  In such a configuration, the driving state of the moving mechanism 6d can be switched between a coating state in which the steel strip S is coated and a standby state in which the steel strip S is retracted. In FIG. 1, the paint state is shown. The coating amount of the coating on the steel strip S can be controlled by controlling the pressing force and the rotational speed for pressing the pickup roll 6a and the applicator roll 6b against each other. In the first embodiment, the amount of coating applied to the steel strip S during operation is controlled to be constant.

  The oven 8 is a furnace for heating the steel strip S to which the paint is applied and drying and baking the paint on the steel strip S. The oven 8 forms a heating space 9 on the inside that is long enough to complete the drying and baking process. By maintaining the heating space 9 in the oven 8 at a predetermined temperature, the steel strip S in the heating space 9 is entirely heated. Since the steel strip S is conveyed in the heating space 9 at a constant speed, the steel strip S is heated toward the downstream side of the heating space 9.

  As shown in FIG. 1, the oven 8 is provided on the downstream side of the coating position 7 by the coating unit 6 in the conveying direction A of the steel strip S. The coating section 6 and the oven 8 are arranged with a space between them, and the coated steel strip S is transported in an unheated state between the coating position 7 of the coating section 6 and the entrance portion of the heating space 9 of the oven 8. It becomes the empty run section 16 to be performed.

  The exhaust unit 10 is a member that exhausts the heating space 9 in the oven 8. In the example of FIG. 1, the exhaust unit 10 includes a duct 10a and a blower 10b. The duct 10a is a pipe directly connected to the heating space 9, and allows the air in the heating space 9 to be vented to the outside. The blower 10b discharges the air ventilated through the duct 10a to the outside.

  The concentration measuring unit 12 is a member that measures the organic solvent concentration of the atmosphere in the heating space 9 (for example, a concentration sensor). The concentration measuring unit 12 shown in FIG. 1 is connected to a position representing the heating space 9 so as to directly measure the organic solvent concentration of the atmosphere in the heating space 9. It is good to provide in the position where the organic solvent density | concentration is assumed to become the highest.

  The control unit 14 is a member that controls the operation of the paint drying apparatus 2. For example, the control unit 14 includes a microcomputer including a memory and a processing circuit corresponding to a processor such as a CPU. The control unit 14 is electrically connected to at least the transport unit 4, the coating unit 6, the exhaust unit 10, and the concentration measurement unit 12, and controls the operation of these members.

  An operation example of the paint drying apparatus 2 configured as described above will be described with reference to FIGS. 2A to 2D.

  First, the temperature is raised (temperature raising step). Specifically, the oven 8 is operated under the control of the control unit 14, the entire heating space 9 in the oven 8 is heated to a predetermined heating temperature (for example, 300 degrees), and the heating temperature is maintained.

  Next, the steel strip S is transported (conveying step). Specifically, as shown in FIG. 2A, the transport unit 4 is operated under the control of the control unit 14, and the steel strip S is continuously transported at a constant speed toward the downstream side (transport direction A).

  Furthermore, painting is performed (painting step). Specifically, as shown in FIG. 2A, the coating unit 6 is operated under the control of the control unit 14, and the paint is applied to the steel strip S being conveyed at the coating position 7. As described above, the coating amount of the coating unit 6 is kept constant per unit time. Thereby, a coating material is apply | coated to the steel strip S by uniform thickness.

  In the example shown in FIG. 2A, a state immediately before the steel strip S to which the paint is applied enters the heating space 9 in the oven 8 is shown. Since the steel strip S travels in an idle running section 16 from the painting position 7 to the entrance portion of the heating space 9, the painted portion of the steel strip S (illustrated by a thick line) is started after painting by the painting section 6 is started. There is a time lag before entering the heating space 9.

  Further, heating is performed (heating step). Specifically, the coated steel strip S is heated in the heating space 9 in the oven 8 maintained at a predetermined heating temperature.

  FIG. 2B shows a state where the steel strip S is further conveyed from the state shown in FIG. 2A. When the coated steel strip S is heated in the heating space 9, the organic solvent contained in the paint applied to the steel strip S evaporates. Since the steel strip S that has entered the heating space 9 at room temperature gradually increases in temperature as it progresses downstream, the organic solvent contained in the paint on the steel strip S starts to evaporate from the most upstream side in the heating space 9. The amount of evaporation gradually increases.

  In FIG. 2B, the evaporation amount 18 which shows the evaporation degree of the organic solvent in the steel strip S is shown. As shown in FIG. 2B, heating and evaporation proceed after the coated steel strip S enters the oven 8, and the evaporation amount 18 of the organic solvent increases toward the downstream side in the transport direction A of the steel strip S. Yes. In FIG. 2B, the evaporation amount 18 is visually indicated by a hatched portion. The height of the hatched portion is the evaporation amount at that position, and the area is the entire evaporation amount.

  Furthermore, the organic solvent concentration in the atmosphere is measured (measurement step). Specifically, the concentration measuring unit 12 is operated to measure the organic solvent concentration of the atmosphere in the heating space 9. In the first embodiment, the concentration measurement unit 12 continuously measures the concentration of the organic solvent, and transmits the measurement result to the control unit 14 as needed.

  Further, exhaust is performed (exhaust step). Specifically, the exhaust unit 10 is operated under the control of the control unit 14 to exhaust the heating space 9. In the first embodiment, the exhaust amount of the blower 10b of the exhaust unit 10 is set constant per unit time.

  FIG. 2C shows a state in which the steel strip S is further conveyed from the state shown in FIG. 2B. As shown in the evaporation amount 20 of the organic solvent in FIG. 2C, the evaporation of the organic solvent is completed at the evaporation end point 22. The remaining paint remaining after evaporation of the organic solvent is further heated in the heating space 9 and is baked onto the surface of the steel strip S.

  FIG. 2D shows a state where the steel strip S is further conveyed from the state shown in FIG. 2C. As shown by the evaporation amount 24 of the organic solvent in FIG. 2D, the region from the entrance of the heating space 9 to the evaporation end point 22 becomes a dry region 23 where the organic solvent is evaporated and dried. A region from the evaporation end point 22 to the exit of the heating space 9 is a baking region 25 where the paint on the steel strip S is heated and baked.

  As described above, since the conveyance speed by the conveyance unit 4, the coating amount by the coating unit 6, and the exhaust amount by the exhaust unit 10 are controlled to be constant, the evaporation amount 24 of the organic solvent in the paint in the oven 8 is stabilized. The state shown in FIG. 2D is maintained.

  Here, as shown in FIG. 2B, after the steel strip S enters the oven 8, the evaporation of the organic solvent proceeds, and the evaporated organic solvent begins to diffuse into the oven 8. As a result, the value measured by the concentration measuring unit 12 starts to change from zero.

  An example of the concentration transition of the organic solvent in the atmosphere in the heating space 9 according to the operation example of FIGS. 2A to 2D is shown in FIG. 2A-2D and the example shown in FIG. 3 show the case where the coating amount by the coating part 6 is normally controlled.

  FIG. 3 shows time on the horizontal axis and the concentration of the organic solvent in the atmosphere of the heating space 9 on the vertical axis. As shown in FIG. 3, the actual average concentration D1 that is the actual average concentration of the organic solvent in the atmosphere of the heating space 9 and the measured concentration D2 that is the organic solvent concentration measured by the concentration measuring unit 12 are the paint drying apparatus 2. After the start of operation (time t0), it gradually increases. As shown in FIG. 3, the measured concentration D2 increases with an increase in the actual average concentration D1. This is because movement is required from the time when the organic solvent on the steel strip S evaporates until it reaches the concentration measuring unit 12. The actual average concentration D1 in the first embodiment is the amount of the organic solvent applied to the steel strip S in the coating unit 6, the distance from the coating unit 6 to the oven 8 (idle running section 16), the capacity of the oven 8, and the exhaust This is a value calculated from the volatilization amount of the organic solvent in the oven 8 based on the exhaust amount from the oven 8 by the unit 10, the speed of the steel strip S, and the like.

  Thereafter, the actual average density D1 and the measured density D2 are both constant and become a steady state.

  In the first embodiment, based on the measured concentration D2 of the organic solvent measured by the concentration measuring unit 12, the control unit 14 calculates the predicted predicted concentration D3. More specifically, the control unit 14 calculates the predicted predicted concentration D3 based on the value when the measured concentration D2 of the organic solvent measured by the concentration measuring unit 12 first changes from 0 (time t1). Thereafter, the calculation of the predicted arrival density D3 is continued.

  The “value when first changed” is not limited to the value when changed from zero during one pulse (for example, 100 ms) of the measurement cycle of the concentration measuring unit 12. It may be a value after time obtained based on past data or calculation results so that this safety measure is established (for example, 0.5 seconds after the organic solvent flows into the oven 8).

  An example of a specific calculation formula for the predicted arrival density D3 is as follows. The following calculation formula is an example, and any other calculation method may be used as long as the predicted predicted concentration D3 is calculated based on the measured concentration D2 of the organic solvent.

<Formula 1>
D3 = D2 / (1-exp (-(t1-x) / T))

  Here, t1 is an elapsed time from the start of coating, x is a variable including a lag time until inflow of the organic solvent, and T is a time constant.

  In the example shown in FIG. 3, the predicted arrival concentration D3 calculated by the control unit 14 at time t1 does not exceed a predetermined threshold concentration D4. As described above, when the arrival predicted density D3 does not exceed the predetermined threshold density D4, the control unit 14 determines that the state is normal and does not perform special control. The threshold concentration D4 is set to a value smaller than the lower limit concentration of the organic solvent.

  2A-2D and FIG. 3 show the case where the coating amount by the coating unit 6 is normally controlled. However, human error when operating the coating drying device 2 and the coating amount of the coating unit 6 are controlled. It is assumed that the application amount is erroneously excessively large from the operation start time (time t0) due to a failure of the control device.

  In preparation for such a case, the coating drying apparatus 2 of Embodiment 1 performs control based on the measured concentration D2 of the organic solvent. Specifically, the predicted arrival density D3 is calculated based on the measured density D2 by the density measuring unit 12, and the actual average density D1 sets the threshold when the predicted arrival density D3 is equal to or higher than a predetermined threshold density D4. Control is performed so that the operation (painting) of the coating unit 6 is stopped before exceeding. In the first embodiment, while the operation of the coating unit 6 is stopped, the transport of the steel strip S by the transport unit 4 is continuously performed, and the transport speed by the transport unit 4 and the exhaust amount by the exhaust unit 10 are not changed. Maintain the same speed and displacement.

  An example of the control is shown in FIGS. 4A to 4D and FIG.

  As shown in FIGS. 4A and 4B, the amount of application by the coating unit 6 is accidentally excessively high, so the evaporation amounts 26 and 27 are significantly larger than the evaporation amounts 18 and 20 shown in FIGS. 2B and 2C. It has become.

  As shown in FIG. 4A, since the organic solvent evaporates when the steel strip S enters the heating space 9 in the oven 8, the measurement result by the concentration measuring unit 12 starts to change. In the first embodiment, the reached predicted concentration D3 is calculated based on the value when the measured concentration D2 of the organic solvent measured by the concentration measuring unit 12 first changes from 0. Specifically, the reached predicted concentration D3 is calculated by the calculation formula shown in Formula 1.

  As shown in FIG. 5, the predicted arrival density D3 calculated by the control unit 14 at time t1 exceeds a predetermined threshold density D4. As described above, when the predicted arrival density D3 exceeds the predetermined threshold density D4, the control unit 14 performs control so as to stop the operation of the coating unit 6 while continuing the operation of the transport unit 4. Specifically, as shown in FIG. 4A, painting by the painting unit 6 is stopped by retracting the painting unit 6 from the painted state to the standby state. Although the coating on the steel strip S is finished at the coating end point 29, the transport of the steel strip S is continued.

  FIG. 4C shows a state in which the transport of the steel strip S by the transport unit 4 is continued in a state where the coating by the coating unit 6 is stopped. As shown in FIG. 4C, the organic solvent does not evaporate upstream from the coating end point 29, which is the point at which the coating unit 6 was last applied. At this time, the evaporation amount 28 of the organic solvent in the entire heating space 9 is smaller than the evaporation amount 27 shown in FIG. 4B (the state at the moment when the coating end point 29 enters the heating space 9 of the oven 8). . Thus, the increase in the concentration of the organic solvent in the heating space 9 is suppressed.

  According to such control, as shown in FIG. 5, the maximum value P of the actual average density D1 can be prevented from exceeding the predetermined threshold density D4 even after the time t1, thereby eliminating the risk of explosion. be able to.

  FIG. 4D shows a state where the steel strip S is further conveyed from the state shown in FIG. 4C. As shown in FIG. 4D, the steel strip S that has been dried and baked is discharged to the outside of the oven 8. Since this steel strip S is due to abnormal operation in which the coating amount of the coating part 6 is set in error, it may be discarded thereafter.

  Thereafter, the cause of the abnormal operation is removed, and the operation is started again in a normal state.

  As described above, the coating and drying apparatus 2 according to the first embodiment is the coating and drying apparatus 2 that performs coating and drying processing while continuously feeding the steel strip S. The coating drying apparatus 2 includes a transport unit 4 that transports the steel strip S, a coating unit 6 that applies a paint containing an organic solvent to the transported steel strip S at the coating position 7, and a coating position 7. An oven 8 for drying the steel strip S in the heating space 9 on the downstream side, an exhaust unit 10 for exhausting the heating space 9 of the oven 8, and a concentration measurement for measuring the concentration of the organic solvent in the atmosphere in the heating space 9 of the oven 8 The control part 14 which controls the operation | movement of the part 12 and the coating drying apparatus 2 is provided. Furthermore, the control unit 14 calculates the predicted predicted concentration D3 based on the measured concentration D2 of the organic solvent measured by the concentration measuring unit 12, and when the predicted predicted concentration D3 is equal to or higher than the predetermined threshold concentration D4, the transport unit 4 Control is performed so as to stop the coating by the coating unit 6 while continuing the conveyance by the above.

  Similarly, the coating and drying method according to the first embodiment is a coating and drying method in which the steel strip S is coated and dried while continuously transporting the steel strip S. The step of transporting the steel strip S and the steel strip S being transported A coating step in which a paint containing an organic solvent is applied at the coating position 7, a drying step in which the steel strip S is dried in the heating space 9 downstream of the coating position 7, and the heating space 9 is exhausted. An exhaust step, a measurement step for measuring the organic solvent concentration in the atmosphere in the heating space 9, a calculation step for calculating the predicted predicted concentration D3 based on the measured measured concentration D2 of the organic solvent, and the predicted predicted concentration D3 is a predetermined threshold value A coating stopping step of stopping the coating while continuing the conveyance of the steel strip S when the concentration is D4 or more.

  According to the above configuration, when the calculated predicted arrival concentration D3 is equal to or higher than the predetermined threshold concentration D4, the increase in the concentration of the organic solvent in the heating space 9 can be suppressed by stopping the operation of the coating unit 6. . Such control enables control to prevent the concentration of the organic solvent in the heating space 9 from becoming excessively high, and prevents the organic solvent from being ignited by heat of the heating space 9 with high accuracy. Can be improved. Furthermore, energy saving during operation can be realized.

  Since the exhaust amount by the exhaust unit 10 can be optimized by the above method and apparatus, the sensible heat of the exhaust gas can be suppressed to a low level, resulting in an improvement in thermal efficiency.

  Moreover, according to the coating drying apparatus 2 of the first embodiment, the control unit 14 is configured to change the measured concentration D2 of the organic solvent measured by the concentration measuring unit 12 from 0 when the coating unit 6 starts coating. Based on the value, the predicted arrival density D3 is calculated. Similarly, according to the coating drying method of the first embodiment, the calculation step calculates the predicted predicted concentration D3 based on the value when the measured concentration D2 of the organic solvent first changes from 0 after the start of coating. .

  According to the said structure, when calculating | requiring the arrival prediction density | concentration D3, the coating stop by the coating part 6 can be rapidly determined by using the value when the measurement density | concentration D2 changes first. Thereby, the raise of the density | concentration of the organic solvent in the heating space 9 can be suppressed rapidly, and safety can further be improved.

  Furthermore, according to the paint drying apparatus 2 of the first embodiment, the control unit 14 maintains the exhaust amount by the exhaust unit 10 at the same amount when the predicted arrival concentration D3 is equal to or higher than the predetermined threshold concentration D4. Stop painting by the paint unit 6. Similarly, according to the paint drying method of the first embodiment, the paint stop step performs the paint stop while maintaining the exhaust amount at the same amount when the arrival predicted concentration D3 is equal to or higher than the predetermined threshold concentration D4.

  According to the said structure, it can implement as a simple mechanism and control compared with the case where an exhaust_gas | exhaustion amount is increased when the organic solvent density | concentration in atmosphere becomes high.

(Embodiment 2)
The coating drying apparatus 30 according to the second embodiment of the present disclosure will be described. In the second embodiment, differences from the first embodiment will be mainly described. In the second embodiment, the same or equivalent components as those in the first embodiment will be described with the same reference numerals. In the second embodiment, descriptions overlapping with those in the first embodiment are omitted.

  In the first embodiment, when the arrival predicted concentration D3 is equal to or higher than the predetermined threshold concentration D4, control is performed to stop the coating by the coating unit 6, but in the second embodiment, in addition to stopping the coating, the transport unit 4 The difference is that the control to slow down the conveyance speed is also performed.

  FIGS. 6A-6D and FIG. 7 show an example of operation of the paint drying apparatus 30 according to the second embodiment and an example of the concentration transition of the organic solvent, respectively.

  As shown in FIG. 6A, as in the first embodiment, the paint unit 6 is retracted from the paint state to the standby state, and the paint by the paint unit 6 is stopped. This is because, as shown in FIG. 7, the arrival predicted density D3 calculated based on the measured density D2 by the density measuring unit 12 at time t1 exceeds the predetermined threshold density D4. In the second embodiment, the control unit 14 further controls the conveyance speed of the conveyance unit 4 to be slow (for example, 40 to 80%). Specifically, as shown in FIG. 6A, the rotational speed of the motor 31 that drives the transport unit 4 is decreased.

  FIG. 6B shows a state where the steel strip S is further conveyed from the state of FIG. 6A. In the state shown in FIG. 6B, the evaporation of the organic solvent is completed at the evaporation end point 32 on the downstream side from the inlet of the heating space 9. Compared with the evaporation end point 22 of Embodiment 1 shown in FIG. 4B, the evaporation end point 32 of Embodiment 2 shown in FIG. 6B is located on the upstream side. This is because the steel strip S is heated for the same time even when the steel strip S is short because the transport speed of the transport unit 4 is reduced.

  In this way, in addition to stopping the coating by the coating unit 6, the amount of paint entering the heating space 9 per unit time is reduced by slowing the conveyance speed by the conveyance unit 4. Thereby, compared with the case where it maintains at the same speed without making the conveyance speed by the conveyance part 4 slow, the evaporation amounts 34 and 36 (FIG. 6C) of the organic solvent in the heating space 9 decrease, and the density | concentration rise of an organic solvent is reduced. Further suppression can be achieved. As shown in FIG. 7, the increase in the actual average concentration D1 of the organic solvent in the heating space 9 after the coating stop (time t1) by the coating unit 6 can be further suppressed. The maximum value P of the actual average density D1 is also lower than that of the first embodiment (FIG. 5).

  As described above, according to the coating drying apparatus 30 of the second embodiment, the control unit 14 controls to slow down the conveyance speed by the conveyance unit 4 in addition to stopping the painting by the coating unit 6. Similarly, according to the coating drying method of the second embodiment, the coating stopping step slows the conveying speed of the steel strip S in addition to stopping the coating.

  According to such control, since the amount of paint entering the heating space 9 per unit time can be reduced by slowing the conveying speed of the steel strip S, the concentration of the organic solvent in the heating space 9 increases. Can be further suppressed. Thereby, safety can be further improved.

  Even though the transport speed is slowed down, if the transport is stopped, even the most upstream portion of the steel strip S in the heating space 9 reaches the heating temperature of the oven 8 (for example, 300 ° C.). Since the organic solvent evaporates all at once from the entire paint that has risen and stopped in the heating space 9, the actual average concentration D1 may exceed the threshold concentration D4 (see the evaporation amount 47 shown in FIG. 10). Therefore, when the conveyance speed is decreased, it is effective to set the speed so as not to approach such a state.

(Embodiment 3)
The coating drying apparatus 40 of Embodiment 3 which concerns on this indication is demonstrated. In the third embodiment, differences from the first embodiment will be mainly described. In the third embodiment, the same or equivalent components as those in the first embodiment will be described with the same reference numerals. In the third embodiment, descriptions overlapping with those in the first embodiment are omitted.

  In the first embodiment, control is performed so as to only stop the coating when the predicted concentration D3 is equal to or higher than the predetermined threshold concentration D4. However, in the third embodiment, in addition to stopping the coating, the coating has already been performed. The difference is that the paint is removed before drying and baking.

  8A-8D and FIG. 9 show an example of operation of the paint drying apparatus 40 according to the third embodiment and an example of the concentration transition of the organic solvent.

  As illustrated in FIGS. 8A to 8D, the coating drying apparatus 40 according to the third embodiment includes a removing unit 42. The removing unit 42 is a member that removes the paint applied to the steel strip S at the application position 7 on the upstream side of the heating space 9 of the oven 8. The removal part 42 shown to FIG. 8A-8D has a plate which can be moved up and down, and is an apparatus which scrapes the coating material on the steel strip S by pressing the front-end | tip of a plate against the surface of the steel strip S. FIG. The lifting / lowering of the plate of the removing unit 42 is controlled by the control unit 14. A tray 43 is provided below the plate, and the paint scraped off by the plate flows down to the tray 43 below.

  As shown in FIG. 9, since the predicted arrival density D3 calculated based on the measured density D2 at time t1 exceeds a predetermined threshold density D4, as shown in FIG. 8A, the coating unit 6 is changed from the painted state to the standby state. Withdrawing, the painting by the painting unit 6 is stopped.

  In the third embodiment, the paint is removed by the removing unit 42 in addition to the stop of painting by the painting unit 6. Specifically, as shown in FIG. 8A, the plate of the removing portion 42 is lowered and brought into contact with the surface of the steel strip S, whereby the paint is scraped off at the tip of the plate. Thereby, the steel strip S in the state where the paint is not applied is conveyed to the heating space 9 of the oven 8.

  FIG. 8B shows a state in which the steel strip S is further conveyed from the state shown in FIG. 8A. In the state shown in FIG. 8B, the evaporation of the organic solvent is completed at the evaporation end point 44. Compared to the evaporation end point 22 of Embodiment 1 shown in FIG. 4B, the evaporation end point 44 of Embodiment 3 shown in FIG. 8B is located at the same point. This is because the third embodiment maintains the same speed without changing the transport speed by the transport section 4 as in the first embodiment.

  On the other hand, since the paint is removed by the removing unit 42, as shown in FIG. 8B, no paint is applied to the upstream portion of the steel strip S in the heating space 9, and the organic solvent evaporates. Not. The coating end point 48 shown in FIG. 8B has moved to a downstream position in the same steel strip S than the coating end point 29 shown in FIG. 4B. Further, the evaporation amount 46 of the organic solvent shown in FIG. 8B is significantly smaller than the evaporation amount 27 of the organic solvent shown in FIG. 4B. Thereafter, as shown in FIG. 8C, the plate of the removal section 42 is raised and returned to the original position, and the applied portion is discharged as shown in FIG. 8D.

  In this way, in addition to stopping the coating by the coating unit 6, the removal of the coating by the removing unit 42 can reduce the amount of the coating that enters the heating space 9 per unit time (Embodiment 3). Then set it to 0). Thereby, the evaporation amount 46 of the organic solvent in the heating space 9 is reduced, and an increase in the concentration of the organic solvent can be suppressed. As shown in FIG. 9, the increase in the actual average concentration D1 of the organic solvent in the heating space 9 after the coating stop (time t1) by the coating unit 6 is further suppressed, and the maximum value P of the actual average concentration D1 is further increased. It is low. In this way, safer control is possible.

  As described above, the coating drying apparatus 40 of the third embodiment further includes the removing unit 42 that removes the paint applied to the steel strip by the coating unit 6 on the upstream side of the heating space 9 of the oven 8. Furthermore, the control unit 14 performs control so that the removal unit 42 removes the paint in addition to stopping the painting by the painting unit 6 when the predicted arrival density D3 is equal to or higher than the predetermined threshold concentration D4. Similarly, according to the paint drying method of the third embodiment, the paint stop step removes the paint applied to the steel strip S at the paint position 7 upstream of the heating space 9 in addition to the stop of the paint. Including the steps of:

  According to the above configuration, the paint applied to the steel strip S (the paint in the idling section 16) is removed upstream of the heating space 9 of the oven 8, so that the paint entering the heating space 9 per unit time is removed. The amount can be reduced. Thereby, the raise of the density | concentration of the organic solvent in the heating space 9 can further be suppressed, and safety can further be improved.

  As described above, the invention of the present disclosure has been described with reference to the above-described embodiment 1-3, but the invention of the present disclosure is not limited to the above-described embodiment 1-3. For example, in Embodiment 1-3, the case where the transport unit 4 is configured by a plurality of rotating rolls has been described. However, the present invention is not limited to such a case, and any configuration is possible as long as the steel strip S can be continuously transported. May be adopted. Moreover, although the said Embodiment 1-3 demonstrated the case where the coating part 6 was comprised with a roll coater, not only in such a case but if a coating material can be apply | coated to the steel strip S, arbitrary structures are employ | adopted. (For example, a slit nozzle). Further, in Embodiment 1-3 described above, the case where the exhaust unit 10 includes the duct 10a and the blower 10b has been described. However, the present invention is not limited to this, and the heating space 9 in the oven 8 can be exhausted. Any configuration may be employed as long as it exists.

  Moreover, although the said Embodiment 1-3 demonstrated the case where it was an apparatus which dries and bakes the steel strip S as the coating drying apparatus 2, it is not restricted to such a case, A drying process is performed without performing a baking process. The present invention can be applied even to a paint drying apparatus that performs only the above.

  In Embodiment 1-3, the case where the concentration measuring unit 12 is directly connected to the heating space 9 has been described. However, the present invention is not limited to such a case. For example, the concentration is measured in the middle of the exhaust duct 10a of the exhaust unit 10. A measurement unit may be provided. Even in such a case, the concentration of the organic solvent in the atmosphere in the heating space 9 can be measured. Thus, the organic solvent concentration in the atmosphere in the heating space 9 may be indirectly measured.

  Moreover, although the said Embodiment 3 demonstrated the case where the removal part 42 had a plate which can be raised / lowered and was attached to the inlet_port | entrance of the oven 8, it is not restricted to such a case. As long as the paint can be removed on the upstream side of the heating space 9 of the oven 8, for example, a removal unit having an arbitrary configuration such as a mechanism for sucking an undried liquid paint may be employed.

  Further, in Embodiment 1-3, the predicted predicted concentration D3 is set based on the value when the measured concentration D2 of the organic solvent measured by the concentration measuring unit 12 first changes from 0 after the coating unit 6 starts painting. Although the case of calculating has been described, it is not limited to such a case. For example, the organic solvent concentration may be continuously measured, and the predicted arrival concentration D3 may be calculated based on the measurement value at an arbitrary timing.

  In the second and third embodiments, in order to reduce the amount of paint that enters the heating space 9 per unit time, control for slowing the transport speed by the transport unit 4 (second embodiment), or removal unit 42. The case where the control for removing the paint on the steel strip S is performed (Embodiment 3) has been described. Other controls may be executed as long as the amount of paint entering the heating space 9 per unit time can be reduced.

  It is to be noted that, by appropriately combining arbitrary embodiments of the various embodiments described above, the effects possessed by them can be produced.

  While the present disclosure has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various variations and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present disclosure as set forth in the appended claims. In addition, combinations of elements and changes in the order in each embodiment can be realized without departing from the scope and spirit of the present disclosure.

  The present disclosure is applicable as long as it is a coating drying apparatus and a coating drying method for coating and drying / baking a steel strip while continuously conveying it.

2, 30, 40 Coating / drying device 4 Conveying unit 6 Coating unit 7 Coating position 8 Oven 9 Heating space 10 Exhaust unit 10a Duct 10b Blower 12 Concentration measuring unit 14 Control unit 16 Free running section 18, 20, 24, 26, 27, 28, 34, 36, 46, 47 Evaporation amount 22, 32, 44 Evaporation end point 23 Drying area 25 Baking area 29, 48 Coating end point 31 Motor 42 Removal part 43 Dish tray A Transport direction D1 Actual average density D2 Measurement density D3 reach Predicted concentration D4 Threshold concentration P Maximum value of actual average concentration S Steel strip

Claims (8)

A coating and drying device that performs coating and drying while continuously conveying steel strips,
A transport unit for transporting the steel strip;
A coating part for applying a paint containing an organic solvent to the steel strip being transported at a painting position;
An oven for forming a heating space for drying the steel strip on the downstream side of the coating position;
An exhaust part for exhausting the heating space;
A concentration measuring unit for measuring the organic solvent concentration of the organic solvent in the heating space;
A control unit for controlling the operation of the paint drying apparatus,
The control unit calculates a predicted arrival concentration based on the organic solvent concentration measured by the concentration measurement unit, and continues the conveyance by the conveyance unit when the arrival predicted concentration is a predetermined threshold concentration or more. A paint drying device that controls to stop painting by the painting unit.   The said control part is a coating of Claim 1 which controls so that the conveyance speed by the said conveyance part may be slowed in addition to the coating stop by the said coating part, when the said arrival density | concentration is more than the said threshold density | concentration. Drying equipment. A removal unit for removing the paint applied to the steel strip by the coating unit on the upstream side of the heating space;
3. The control unit according to claim 1, wherein, when the predicted predicted concentration is equal to or higher than the threshold concentration, in addition to stopping the coating by the coating unit, the control unit performs control so that the paint is removed by the removing unit. Paint drying equipment.   The said control part is controlled to perform the coating stop by the said coating part, maintaining the exhaust_gas | exhaustion amount by the said exhaust part at the same amount, when the said arrival density | concentration is more than the said threshold density | concentration. The paint drying apparatus as described in any one of these. A coating and drying method in which a steel strip is coated and dried while being continuously conveyed,
Conveying the steel strip;
A coating step of applying a coating containing an organic solvent to the steel strip being transported at a coating position;
A drying step of drying the steel strip in a heating space on the downstream side of the coating position;
An exhaust step for exhausting the heating space;
A measuring step for measuring an organic solvent concentration of the organic solvent in the heating space;
Based on the measured organic solvent concentration, a calculation step for calculating a predicted concentration reached;
When the predicted arrival concentration is equal to or higher than a predetermined threshold concentration, a coating stop step for stopping the coating while continuing to convey the steel strip;
Including a paint drying method.   The continuous coating drying method according to claim 5, wherein the coating stopping step includes a step of slowing a conveyance speed of the steel strip in addition to stopping the coating when the predicted predicted concentration is equal to or higher than the threshold concentration.   The coating stop step removes the paint applied to the steel strip at the coating position on the upstream side of the heating space in addition to stopping the coating when the predicted predicted concentration is equal to or higher than the threshold concentration. The continuous paint drying method of Claim 5 or 6 including the step to perform.   The continuous paint drying according to any one of claims 5 to 7, wherein the paint stop step stops the paint while maintaining the exhaust amount equal when the predicted arrival concentration is equal to or higher than the threshold concentration. Method.

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