JPH03154A - Dryer - Google Patents

Abstract

PURPOSE:To prevent baking failure of a coated film by providing a dryer for controlling temp. so that a material to be baked is regulated to the baking temp. on the basis of both the temp. detection value of a temp. sensor and heat capacity of the material to be coated. CONSTITUTION:Such a thermal response curve is obtained that the surface temp. of a material W to be coated reaches the prescribed baking temp. in the interval until the material W to be coated is transferred to a curing zone Z2 from a point of time when the surface temp. of the material W has been detected by a temp. sensor 4. A controlling signal is output by which the combustion amount of a burner 8 and the feed amount of a fan are controlled for a hot air generator 7 for supplying hot air to a thermal radiation duct 2 so that the surface temp. is raised while drawing this thermal response curve. Thereby such possibilities are eliminated that baking failure and overbake are caused on the film of the material W baked in the curing zone Z2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a drying apparatus for feeding an object to be coated into a tunnel-type drying oven to bake a coating film.

[Conventional technology]

In this type of drying equipment, the inside of the tunnel-type drying oven is divided into a temperature rising zone and a curing zone, and the surface temperature of the coated material passing through the drying oven at a predetermined speed is controlled at a predetermined temperature in the temperature rising zone. The baking temperature is raised to (usually about 170 to 180'C), and the coating film on the object to be coated is reacted and cured over a certain period of time in the next curing zone.

In the curing zone, in order to prevent poor baking and overbaking of the paint film, the ambient temperature inside the drying oven is detected with a thermometer such as a thermocouple, and the atmosphere is maintained at an equilibrium temperature, which is the predetermined baking temperature. (Japanese Unexamined Patent Application Publication No. 1983-1999)
185359 and JP-A-62-62178).

[Problems to be Solved by the Invention] However, simply maintaining the atmosphere of the curing zone at a constant equilibrium temperature in this way has not been able to completely prevent defective baking and overbaking of the coating film.

The reason for this is that when the atmospheric temperature in the heating zone changes due to external disturbances, etc., and when the workpiece passes through the heating zone and moves to the curing zone, the surface temperature still remains at the specified baking temperature. This is because the actual baking time may be too short or too long because the temperature has not been reached or, conversely, the baking temperature has already been reached while passing through the temperature raising zone.

In order to prevent such problems, it would be possible to detect the ambient temperature in the heating zone in the same way as in the curing zone and adjust the temperature to a constant level. In a mixed production line where a mixture of materials are conveyed, the heat capacity of each object heated in the heating zone is different, so the graph in Figure 3 shows that the ambient temperature is constant. As such, the time required to reach the baking temperature differs depending on the size of the heat capacity, and objects with a small heat capacity reach the baking temperature while passing through the heating zone, so the baking time of the coating film will be longer. Since the object to be coated, which has a large heat capacity, does not reach the baking temperature yet when it moves from the temperature raising zone to the curing zone, the baking time of the coating film becomes short, resulting in a baking defect.

Therefore, the present invention has been developed so that even in a mixed production line where objects to be coated of different sizes are conveyed together, each object to be coated reaches a predetermined baking temperature just as it moves from the temperature rising zone to the curing zone. The technical challenge is to achieve this goal.

[Means to solve the problem]

In order to solve this problem, the drying device according to the present invention
A non-contact humidity and temperature sensor is provided to detect the surface temperature of the object to be coated as it is heated in the heating zone of the tunnel drying oven, and based on the temperature detection value of the temperature sensor and the heat capacity of the object to be coated, It is characterized by being provided with a temperature control device that adjusts the heating temperature of the object to be coated so as to draw a thermal response curve such that the object to be coated reaches a predetermined baking temperature when it moves to a curing zone. .

[Effect]

According to the present invention, instead of detecting the ambient temperature in the temperature increasing zone, the surface temperature of the object to be coated heated in the temperature increasing zone is detected by a non-contact humidity temperature sensor.

Based on the surface temperature of the workpiece detected by the temperature sensor and the heat capacity of the workpiece, the temperature control device determines whether the surface temperature is just when the workpiece transitions from the temperature rising zone to the curing zone. The heating temperature of the object to be coated is set to 1! so that it rises with a thermal response curve that reaches the predetermined baking temperature. ! make a clause

As a result, even if the objects to be coated have different heat capacities depending on their size, the surface temperature of each object when it passes through the temperature increase zone and moves to the curing zone will reach the desired baking temperature. Reach temperature.

Therefore, it is possible to prevent baking defects and overbaking from occurring in the coating film of the object to be coated, which is baked over a certain period of time in the curing zone.

〔Example〕

Embodiments of the present invention will be specifically described below based on the drawings.

FIG. 1 is a block diagram schematically showing an example of a drying apparatus according to the present invention, and FIG. 2 is a graph showing its operation.

The tunnel type drying furnace 1 has a temperature increasing zone Zl that heats the coated IFJw by radiant heat emitted from the thermal radiation duct 2.
and a curing zone Z2 where the object W to be coated is heated by the hot air blown out from the hot air blowing duct 3.

The temperature increasing zone Zl is provided with a non-contact humidity temperature sensor 4 that detects the surface temperature of the object to be coated W heated within the zone.

This temperature sensor 4 is a radiation thermometer that detects energy radiated by an object according to its temperature and measures the temperature of the object in a non-contact manner.

5 is a temperature control device that adjusts the heating temperature of each workpiece W based on the temperature detection value input from the temperature sensor 4 and the heat capacity data of each workpiece W input from the setting device 6; As shown in the graph of FIG.
From the time when the surface temperature of the object W to be coated is detected to the time when the object W to be coated moves to the curing zone Z2,
Thermal response curves ■ to ■ such that the surface temperature of the object W to be coated reaches a predetermined baking temperature are determined, and the heat radiation duct 2 is set so that the surface temperature is increased while drawing the thermal response curves ■ to ■. A control signal for adjusting the combustion amount of the burner 8 and the air supply amount of the fan 9 is output to the hot air generator 7 that supplies hot air.

As shown in Fig. 2, the surface temperature of the object W with a small heat capacity draws a thermal response curve ■ and reaches the predetermined baking temperature, and the surface temperature of the object W with a large heat capacity shows a thermal response curve. The baking temperature is reached by drawing a curve (■), but in any case, the baking temperature is reached when each object W is in the temperature rising zone Z,
It is now time to move from curing zone Z2.

Therefore, even if the drying device is used for a mixed production line in which objects W to be coated with different heat capacities are conveyed in a mixed manner, the coating film of each object W to be baked in the curing zone Z2 is
There is no risk of poor baking or overbaking.

In addition, when the conveyance pitch between each workpiece W is small and two workpieces W, front and rear, pass in front of the thermal radiation duct 2 at the same time, the thermal radiation duct 2 is divided into front and rear parts, and The amount of radiant heat radiated from the side heat radiant duct is calculated for each workpiece W.
You can adjust it accordingly.

〔Effect of the invention〕

As described above, according to the present invention, even when objects to be coated with different heat capacities are fed into the tunnel drying furnace, each object to be coated moves from the temperature increasing zone to the curing zone. Since the predetermined baking temperature is reached exactly when the baking time is applied, it has the excellent effect of reliably preventing defective baking and overbaking of the paint film that would occur if the baking time was too short or too long.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing an example of a drying apparatus according to the present invention, FIG. 2 is a graph showing its operation, and FIG. 3 is a graph showing problems of the prior art. Description of symbols W... - object to be coated, 1 - - tunnel type drying oven, Zl - temperature raising zone, Z2 - curing zone, 2 -
Thermal radiation duct, 3-hot air blowing duct, 4...-non-contact temperature sensor, 5...-temperature control device, 6-setting device, 7-
・Hot air generator, 8-burner, 9-fan.

Claims (1)

[Claims] A non-contact temperature sensor (4) is provided to detect the surface temperature of the workpiece (W) being heated in the temperature increasing zone (Z_1) of the tunnel drying oven (1). ) and the heat capacity of the object to be coated (W), determine the heating temperature of the object to be coated (W).
It is characterized by being provided with a temperature control device (5) that adjusts to draw a thermal response curve ((1) to (3)) that reaches a predetermined baking temperature when transitioning to the curing zone (Z_2). drying equipment.