JPH0614826Y2 - Infrared heating furnace - Google Patents

Description

[Detailed Description of the Invention] [Industrial application] The present invention relates to an improvement of an infrared heating furnace provided with an infrared heater.

[Conventional technology]

Conventional infrared heating furnaces include a single-sided bank type that irradiates infrared rays from one side of the object to be heated to perform local heating, and a double-sided type that irradiates infrared rays evenly from both sides of the object to be heated to perform overall heating. There is a bank type.

By the way, in the manufacture of automobile doors, when heat treatment is performed to cure the thermosetting sealant that has been caulked at the joint between the outer panel (outer panel) and the inner panel (inner panel), the entire automobile door and inner panel are to be cured. It is common to use a double-sided bank type infrared heating furnace that uniformly heats both sides of the panel.

[Problems to be solved by the invention]

However, when a double-sided bank type infrared heating furnace is used to heat an automobile door formed by joining an outer panel and an inner panel, the automobile door may be deformed due to thermal strain, or the sealing material may be peeled off. there were.

When the inventors investigated the cause of this, infrared rays are converted into heat energy when hitting an object to be heated such as an automobile door, and a very strong thermal action is exerted, but the atmosphere itself in the heating furnace is directly heated to a high temperature. Therefore, when the object to be heated is loaded and unloaded by opening the open / close door of the heating furnace, the temperature inside the furnace drops significantly, and when the object to be heated is loaded into the furnace in this state, the object to be heated is preheated. It turned out that it was because it was suddenly heated to a high temperature of 200 ° C to 300 ° C by being irradiated with infrared rays. Particularly in winter, when the open / close door of the heating furnace is opened, a large amount of cold outside air enters and the atmospheric temperature in the furnace is significantly lowered, so that there is a great possibility of causing thermal strain.

That is, FIG. 3 is a graph showing the rising curve of the irradiation temperature by dividing the illuminance (W / cm ² ) of the infrared rays radiated on the object to be heated into four stages. It can be seen that the irradiation temperature rises rapidly in a shorter time as the irradiation illuminance is increased and the set value of the maximum temperature is increased. This is because the infrared rays are intensively irradiated to the object to be heated and are not irradiated to the surroundings that do not require heating, so the energy loss is very small, and the infrared rays are converted into thermal energy when they hit the object to be heated. Because the thermal action is very strong.

Therefore, when the car door is carried into the furnace where the maximum temperature of the infrared heater is set to 200 ° C to 300 ° C, and the irradiation of infrared rays is started without preheating the car door at all,
The radiant heat causes the automobile door to suddenly be partially heated from a low temperature state to a high temperature of 200 ° C or higher, causing a remarkable deformation due to a temperature gradient thermal strain.

In order to prevent such an adverse effect, instead of a radiant heating furnace using infrared rays, a combustion gas generated from a heat source or hot air directly or indirectly heated by the combustion gas is used as a hot air furnace. It is also a good idea to use a convection-type heating furnace that circulates the gas inside the furnace to heat the whole, but this convection method has much lower thermal efficiency than the radiation method, and it takes a long time to preheat the inside of the furnace. Since the rate of temperature rise of the object to be heated is slow, the productivity of heat treatment is significantly reduced. Also, in order to increase productivity by using a convection heating furnace with poor thermal efficiency, a large amount of objects to be heated must be loaded into the furnace at once, which inevitably increases the furnace length. There is a problem that a very large installation space is required.

[Means for solving problems]

Therefore, the present invention can prevent the adverse effect that the heated object carried into the furnace is rapidly heated and causes thermal strain, and at the same time, the heated object carried into the furnace is heated efficiently and quickly to the required temperature. It is intended to provide an infrared heating furnace capable of increasing productivity.

In order to achieve this object, the infrared heating furnace according to the present invention includes an infrared heater that irradiates infrared rays toward the upper surface side of the heated object carried into the furnace, and burns toward the lower surface side of the heated object. A gas burner that reflects heat is disposed at positions facing each other with the object to be heated interposed therebetween, and is also vertically movable so as to be able to approach or separate from the object to be heated. Is characterized by.

[Action]

According to the present invention, high-temperature hot air generated by the combustion of the gas burner is convective in the furnace, so that the temperature inside the furnace is surely lowered when the object to be heated is carried in and out by opening the opening / closing door of the heating furnace. Be restrained by.

As a result, the object to be heated that has been loaded into the furnace by opening the opening / closing door of the heating furnace is first adapted to the ambient temperature in the furnace where convection of high-temperature hot air occurs, and the upper and lower surfaces are evenly preheated.

Next, the upper surface side and the lower surface side of the object to be heated preheated by the hot air convection in the furnace as described above are efficiently heated by the radiant heat of infrared rays emitted from the infrared heater and the combustion heat of the gas burner.

Therefore, the object to be heated carried into the furnace is quickly heated to the required temperature without causing thermal strain.

In addition, since the infrared heater and the gas burner can be kept away from the object to be heated until the object to be heated is adapted to the ambient temperature in the furnace, it is possible to more reliably prevent the occurrence of thermal strain due to rapid heating. .

〔Example〕

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

1 and 2 are a side view and a front view showing an example of an infrared heating furnace according to the present invention.

The infrared heating furnace 1 has a loading / unloading port 2 which is opened in the front thereof.
An opening / closing door 3 is provided in the vehicle, and the opening / closing door 3 is opened to carry in / out the automobile door 4 as an object to be heated into / out of the furnace. Further, in the furnace of the heating furnace 1, an infrared heater H that radiates infrared rays toward the upper surface side of the automobile door 4 carried into the furnace, and a gas burner that radiates combustion heat toward the lower surface side of the automobile door 4. B and B are arranged to face each other.

The infrared heater H is formed by arranging a required number of near infrared heater units 5, 5 ... Having an effective emission wavelength of 5 μ or less on the upper frame 7, and the gas burner B is a relatively clean gas such as city gas or LP gas. A required number of burner units 6, 6 ... Using gas as fuel are arranged side by side on the lower frame 8.

The upper frame 7 is screwed onto a plurality of feed screw rods 9, 9 ... Hanging from the ceiling of the heating furnace 1 and hung horizontally. A sprocket 10 is provided on each of the feed screw rods 9, 9 ... And an endless chain 11 is hung between these sprockets to form a specific feed screw rod 9.
The bundle 12 attached to the upper frame 7 is rotated to interlock with the other feed screw rods 9, 9 ,.
It is designed to be able to move up and down.

The lower frame 8 is horizontally supported by being screwed onto a plurality of feed screw rods 13, 13 ... Standing on the bottom of the heating furnace 1. And each feed screw rod 13, 13 ...
Each of them is provided with a sprocket 14, and a sprocket 16 provided on a rotary shaft 15 standing upright outside the heating furnace 1 in parallel with the feed screw rods 13, 13 ,. The endless chain 17 is hung between the sprocket 14 and the sprocket 14, and the handle 18 attached to the rotary shaft 15 is turned to rotate the feed screw rods 13, 13.
... are interlocked with each other so that the lower frame 8 can be moved up and down.

The burner units 6, 6 of the gas burner B arranged side by side on the lower frame 8 have the burner units in the front row and the rear row in the central row when viewed from the loading side of the vehicle door 4 loaded and unloaded on the carriage 19. It is connected to the unit by a hinge 20, and is rotated up and down with each hinge 20 as a fulcrum by an angle varying mechanism 21 so that the angle can be adjusted according to the shape of the lower surface side of the automobile door 4.

In the figure, reference numeral 22 denotes a heater cooling flexible duct provided to prevent heating of the infrared heater H.

The above is the configuration of the infrared heating furnace 1 according to the present invention, and its operation will be described below.

First, by operating the handle 12 and the handle 18 to move up and down the upper frame 7 and the lower frame 8, respectively,
The distance between the infrared heater H facing the upper surface side of the automobile door 4 carried into the heating furnace 1 and the gas burner B facing the lower surface side is properly adjusted in advance, respectively, and each angle burner of the gas burner B is controlled by the angle varying mechanism 21. Units 6, 6 ...
The angle of ... Is adjusted in advance according to the shape of the lower surface side of the automobile door 4.

In this state, the opening / closing door 3 provided at the loading / unloading port 2 is closed and the infrared heater H and the gas burner B are operated to heat the atmosphere in the heating furnace 1 to a required temperature (for example, 200 ° C. to 300 ° C.).

When the atmosphere in the heating furnace 1 reaches the required temperature,
The vehicle door 4 is loaded into the furnace from the loading / unloading port 2 by opening the open / close door 3, and the upper surface side and the lower surface side of the loaded vehicle door 4 are
The infrared radiant heat emitted from the infrared heater H and the combustion heat radiated from the gas burner B are evenly heated.

The automobile door 4 that has been heated in this way is the opening / closing door 3
Is opened and is carried out of the furnace through the carry-in / out port 2, and the next new automobile door 4 is carried into the furnace.

At this time, a part of the hot air filling the heating furnace 1 escapes from the carry-in / out port 2 to the outside, but new hot air is generated in the heating furnace 1 one after another due to the combustion of the gas burner B. Because of the convection caused by the convection, the decrease of the temperature in the furnace is surely suppressed.

As a result, the automobile door 4 carried into the heating furnace 1 through the carry-in / out port 2 is adapted to the ambient temperature in the furnace where the hot air generated by the combustion of the gas burner B is convected, and its upper and lower surfaces are evenly preheated. It

Then, the automobile door 4 preheated by the high-temperature hot air convective in the furnace in this manner, the radiant heat of the infrared rays radiated from the infrared heater H on the upper surface side and the lower surface side thereof, and the gas burner B
It is heated with good heat efficiency by the combustion heat emitted from the.

Therefore, the automobile door 4 carried into the heating furnace 1 is prevented from being rapidly heated from a low temperature state to be deformed due to thermal strain, and the lower surface side of the automobile door 4 is radiated from the gas burner B. An automobile door 4 which is heated by combustion heat and cannot be effectively heated only by convection of hot air generated by combustion of the gas burner B.
Is heated by the radiant heat of infrared rays emitted from the infrared heater H, so that the entire automobile door 4 is quickly heated to a required temperature, and the productivity thereof is enhanced.

Immediately before the automobile door 4 is loaded into the heating furnace 1, the handle 12 and the handle 18 are operated to make the infrared heater H and the gas nanar B stand by at a position away from the automobile door 4, and the automobile door 4 is heated. If the infrared heater H and the gas burner B are adjusted so as to approach the vehicle door 4 to an appropriate distance when the vehicle is brought into the furnace 1 and completely adjusted to the ambient temperature in the furnace, the vehicle door 4 suddenly moves. It is possible to more reliably prevent the occurrence of thermal strain due to stable heating.

[Effect of device]

As described above, in the infrared heating furnace according to the present invention, high temperature hot air generated by the combustion of the gas burner is convected in the furnace, so that it occurs when the object to be heated is carried in and out by opening the opening / closing door. The temperature inside the furnace can be surely suppressed from falling, and at the same time, the heated object carried into the furnace can be preheated by adjusting it to the ambient temperature inside the furnace. There is a very excellent effect that the adverse effect that the object is abruptly heated from the low temperature state and the thermal strain is prevented. Further, the lower surface side of the heated object carried into the furnace is effectively heated by the combustion heat of the gas burner, and the heating rate becomes slow only by convection of the hot air generated by the combustion of the gas burner into the furnace. The upper surface of the object to be heated is effectively heated by the radiant heat of the infrared rays emitted from the infrared heater. Can be increased.

[Brief description of drawings]

1 and 2 are a side view and a front view showing an example of an infrared heating furnace according to the present invention, and FIG. 3 is a graph showing an increase curve of irradiation temperature according to irradiation illuminance of infrared rays. Explanation of symbols 1 ... Infrared heating furnace, 2 ... Carry-in / out port, 3 ... Open / close door,
4 ... Automotive door (object to be heated), H ... Infrared heater, B ... Gas burner.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Satoshi Yasumatsu 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (56) Reference JP-A-47-29606 (JP, A) JP-A-59-105871 (JP, A) JP-A-62-117661 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A heated object (4) carried into a furnace (1).
An infrared heater (H) that radiates infrared rays toward the upper surface side of the object and a gas burner (B) that radiates combustion heat toward the lower surface side of the object (4) to be heated heat the object (4) to be heated. An infrared heating furnace, wherein the infrared heating furnace is arranged at positions facing each other, and is so arranged as to be movable up and down so as to approach or separate from the object to be heated (4).