JPH02284671A - Baking furnace for coating - Google Patents

Abstract

PURPOSE:To stably and surely bake the whole body at the prescribed temp. in the prescribed time and to achieve high-quality coating by integrally providing a concentrating and blasting means to a dolly wherein hot air discharged from a blowout port connected to a hot air generator is led to the bottom part of a work and blasted thereon. CONSTITUTION:A furnace body 1 is provided which is equipped with a hot air generator 10, the upper blowout port 7 for blasting the hot air led from the generator 10 to the side part of a work W and the lower blowout port 9 for blasting the hot air to the bottom part thereof. An air introducing port 3a correspondent to the lower blowout port 9 is provided to a dolly 2a carrying the work W. Furthermore a blasting port 3d correspondent to the bottom part Wb is provided. The air introducing port 3a is communicated with the blasting port 3d in the inside of the dolly 2a. As a result, overbaking of the side part or noncompletion of baking of the bottom part is swept off. The whole body is stably and surely baked at the prescribed temp. in the prescribed time and high-quality coating is achieved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a baking furnace for painting.

[Prior Art] A painting operation consists of a coating process by spraying, electrodeposition, etc., and a baking process in which the coated product (hereinafter referred to as a work) is dried and baked.

In order to obtain high-quality painted products, it is important not only to improve coating film uniformity and adhesion during the coating process, but also to maintain uniform and stable baking temperature and baking time, which are the basic conditions during the baking process. be. For example, in the case of an automobile body coated with a cationic paint, the baking temperature is 180° C. and the baking time is 20 minutes.

Therefore, conventional baking furnaces for painting require long-term treatment at such high temperatures, and as shown in Japanese Utility Model Publication No. 60-7814 and Japanese Utility Model Publication No. 62-43264,
Generally, the structure is such that hot air is circulated from a hot air generator while the workpiece is moved in the longitudinal direction of the tunnel type furnace body using a conveying means.

Here, method 1 of blowing hot air onto the workpiece is to provide a hot air outlet on the side of the workpiece for convenience of layout such as movement of the workpiece and circulation of hot air, and also to install a hot air outlet on the side of the workpiece from the viewpoint of changing the height of the workpiece. The suction port is located above the hot air outlet.

For this reason, while the hot air from the outlet maintains a constant temperature inside the furnace, it generally forms an upward air current, so it is often difficult to maintain the bottom of the workpiece at a predetermined temperature. .

That is, as shown in FIG. 4, when the workpiece enters the baking area, the temperature of the side part Ws quickly rises and reaches the predetermined baking temperature r, but the temperature of the bottom part Wb rises slowly and the baking process continues. It is lower than 4 Onru by Δ. Therefore, since the length of the burning area and the moving speed of the workpiece are constant, either the fullJ part Ws satisfies the prescribed burning time BT, or the bottom part Wb has a burning time BT' even if the above △ is within the allowable range. This is insufficient. On the other hand, if the predetermined baking time is BT' and the predetermined baking temperature is T', the side portion Ws will be overbaked, which is a misconception.

Therefore, as proposed in the above-mentioned Japanese Utility Model Publication No. 60-7814, air outlets (4A, 4B) are directed toward the side of the workpiece (1).
), there is also an air outlet (nozzle 21A) directed toward the bottom to resolve the problem of insufficient hot air circulation.

21B) to supplement the temperature maintenance at the bottom.

[Problem to be Solved by the Invention 1] By the way, the above-mentioned complementary method divides the hot air from the hot air generator (7) to the two blow-off ports (4A, 4B and 21A, 21).
B). That is, by forcibly increasing the amount of hot air per unit time to the bottom of the workpiece, it is attempted to indirectly raise the temperature by 1.

However, because of the size and shape of the work occupying the space inside the furnace, there is still an upward air current, so the effect of maintaining the temperature at the bottom wb is low even though the amount of hot air is increased. Moreover, since the temperature is to be maintained not at the entire bottom of the workpiece but at a portion thereof, it is not possible to expect an effect commensurate with the improvement of equipment.

In addition, in actual operation]7, it is not only difficult to adjust the amount of hot air to a reasonable level, but also changing the setting of the baking temperature may cause over-paking or incomplete baking. Ta.

Furthermore, conventional structures are no longer able to meet the current demands for high quality and diversification of layers.

That is, when the workpiece is an automobile body, the so-called body floor forming the bottom has a complicated shape, and t is also large, so indirect temperature rise tends to result in insufficient baking temperature. Also, the paint film on the body floor has +1 resistance compared to others.
! ! ! When the thickness becomes even thicker in terms of the direction of production f-, etc., it is no longer possible to track it using the written complementation method.

In addition, this problem is not limited to the one-jet two-component spraying method in which hot air is directly sprayed onto the workpiece.For example, heating ducts are installed on both sides of the furnace body, and hot air is guided into the heating ducts to utilize radiant heat. This problem also occurs in the case of the so-called radiant heating method.

The present invention was made in view of the above circumstances, and its purpose is to achieve a predetermined baking temperature by blowing hot air intensively onto the bottom of the workpiece without overbaking or other effects on the pond area. To provide a paint baking furnace that can quickly set up and maintain high-quality baking reliably and stably.

[Means for Solving the Problem 1] The invention as set forth in claim 1 provides a hot air generator, an upper blower outlet for blowing the hot air guided from the hot air generator to four parts of a workpiece, and a lower part for blowing the hot air to the bottom of the workpiece. In a painting baking furnace formed of a furnace body having a blowout [1], the trolley for transporting the workpiece is provided with an air guide [ ] corresponding to the bottom blowout [1] and a blowing blower corresponding to the bottom part. It has a configuration in which an opening is provided and the air guide opening and the blower (10) are communicated with each other inside the truck.

In addition, the invention as claimed in claim 2 provides a coating baking to 1 furnace formed including a furnace body having a hot air generator and a heating duct that radiantly heats a workpiece with hot air guided from the hot air generator, An air outlet is provided in the furnace body for blowing hot air guided from the hot air generator onto the workpiece, and an air guide port corresponding to the air outlet is provided on a cart for transporting the workpiece, and an air outlet is provided in correspondence with the bottom of the workpiece. , and the air guide 1 and the blower ``l'' are communicated within the truck.

[Function] In the invention described in claim 1, the hot air from the upper air outlet is blown onto the side of the workpiece, and the hot air from the lower air outlet is directed to the concentrated blowing means, that is, the air guide port and the communication passage installed on the cart. Spray efficiently and intensively from the spray port to the desired bottom area (
1rah,ru.

Moreover, the relative position of the bottom and the spray nozzle is
Since it remains constant regardless of the movement of the ball, it can be effectively blown without being deflected.

7. As a result, the bottom of the workpiece can be baked as well as other parts, and there is no effect of overbaking on other parts, and overall thermal efficiency is high and quick and high-quality coating can be achieved. be able to.

Moreover, in the invention described in claim 2, the entire workpiece is uniquely heated by radiant heat from the heating duct. At the same time,
The hot air from the outlet is efficiently and efficiently blown from the outlet to a desired bottom portion through a concentrated blowing means attached to the truck, that is, an air guide port and a communication passage.

Moreover, the relative position of the bottom and the spray port is
Since it remains constant regardless of the movement of the air, it can be blown efficiently without being deflected.

Therefore, the bottom of the workpiece can be baked as well as other parts, and the temperature can be quickly increased as in the case of the invention described in claim 2, without affecting other parts by overbaking or the like. It is possible to achieve quality painting.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

(First Example) As shown in Fig. 1 (overall configuration diagram), this baking furnace for painting is as follows:
Broadly speaking, it is composed of a tunnel type furnace body 1, a conveyance means 2, a concentrated blowing means 3, a hot air generator 10, a circulation system 20, and a control means 30.

First, a furnace body 1 is thermally insulated around its periphery, and is provided with a transport means 2 inside thereof for moving a workpiece W made of an automobile body at a constant speed in the longitudinal direction (direction perpendicular to the plane of the paper in FIG. 1). There is. The conveyance means 2 is a cart 2a with wheels 2c, 2c.
, a carrier 2b for fixing the workpiece W to the cart 2a, a rail 2d, and a side drive Ia (not shown).

A pair of upper blowing ducts 1-6.6 are installed on both sides of the furnace body l.
and F blower 4 tacts 8, 8, and above these suction ducts 1 to 23 and 23 for exhaust are arranged.

In addition, the soil 2 part blowout lower is provided in the upper blowing duct 1 to 6 and faces the side Ws of the i-work W, and the lower blowing outlet 9 is provided in the lower blowing duct 8 and is formed to blow hot air into the concentrated blowing means 3. has been done.

Here, the concentrated blowing means 3 is a means for blowing hot air intensively and efficiently onto the bottom Wb of the workpiece W (=tCf), and as shown in FIGS. It is formed from an air passage 3C and a blowing port 3d, and is integrally attached to the truck 2a.

The air guide port 3a has a plurality of lower air outlets [
19, with an opening 3b at the end thereof.
The diameter is enlarged in the direction of air guiding efficiency. Opening 3
b and the corresponding lower air outlet 9 should be arranged closer to each other as long as it allows for convenience of transportation and flexibility in changing the type of workpiece W. However, it is not necessary that both 3b and 9 communicate with each other in a completely sealed manner.

If the trolley 2a moves with respect to the lower air outlet 9 and the position relative to the air guide port 3a is shifted, the hot air from the lower air outlet [19] lowers the temperature of the entire lower side of the workpiece W, which is relatively low in temperature. This is because it can be effectively used for raising the temperature.

Further, the number of blowing ports 3d corresponds to the number of air guide ports 3a,
The bottom part wb is arranged facing upward.

A rectifying distribution plate 3e whose angle can be adjusted is provided at each blowing port 3d to carry out concentrated spraying.

Note that the air guide path 3c has a corresponding air guide port 3a and a blowing port 3d.
It is formed from a duct.

However, depending on the form of the truck 2a, the truck structure itself may be used.

Therefore, the hot air from the lower outlet 9 is stably blown efficiently and intensively to the specific bottom part wb via the concentrated blowing means 3 regardless of the movement of the workpiece W.

Furthermore, in this embodiment, not only is it intended to achieve effective local concentrated spraying, but also to achieve a prescribed baking time within a prescribed time even when the coating film on the bottom part Wb is thick. The hot air generator 10, the circulation system 20, and the control means 30 have a special configuration in order to economically increase the temperature of the hot air blown onto the air.

This hot air generator 10 is a means for generating two types of hot air with different temperatures, and in this embodiment, it is configured as a mixing method using one burner device 11 from the viewpoint of improving thermal efficiency and advantageous equipment economy. There is. That is, the hot air at a temperature (T h ) generated by the burner device 11 is treated as hot air at a high temperature Th, and the hot air at a low temperature TI is mixed with the exhaust air at a relatively low temperature i' c in the mixing unit 15. It is supposed to be obtained by mixing. Low temperature hot air is
The temperature can be lowered by increasing the opening degree of the manual damper 19.

In this way, the generated low-temperature hot air at the temperature TI is energized by the fan 14, guided to the low-temperature supply duct 1 via 21 to the rain blowing duct l, and then from the upper blowing lower, 7. It is blown out toward the side Ws of the workpiece W. On the other hand, temperature T
The high-temperature hot air of h passes through the fan 17, the high-temperature supply tact 22, and the lower blowing duct 8.8, and is blown out from the lower blowing ports 9, 9 through the concentrated blowing means 3 toward the bottom wb.

In this example, in consideration of the properties of the paint, the form and heat capacity of the workpiece W (side part Ws, bottom part wb), baking time, etc., the temperature T1 of the low-temperature hot air, which is the basic baking temperature, is set to 160°C, and the complementary baking temperature is set to 160°C. Assuming the temperature TF1 of high temperature hot air is 180℃, 20
A temperature difference of 0.degree. C. is provided, and the flow rate ratio between the high temperature hot air flow iQ and the low temperature hot air Qh is set to 1=9.

Here, in this embodiment, the flow of hot air inside the furnace body 1 is generally an upward air flow, and the tolerance 1 of the bottom part wb is higher than that of the side part Ws.
Considering that the coating film on the bottom wb is large or thicker than other parts, and that the baking time is set to a certain minimum time, it is necessary to take a relatively long time to reach the prescribed baking temperature. By directly increasing the heat energy supplied to the bottom part wb by the concentrated spraying means 3 and without causing a large change in the overall hot air volume balance, It is understood that the entire workpiece is baked more uniformly and simultaneously.

Next, the hot air circulation system 2Q is connected to the low temperature supply duct 21.
, high temperature supply duct I/22, and both suction ducts h23,2.
3, and a circulation duct I/24 that connects both suction ducts 23, 23 and the hot air generator 10. Therefore, except for the combustion air supply in the burner device 11,
forming a closed loop.

The control means 30 includes a baking temperature control system 31 and a flow rate control system 35.
This system guarantees quick and accurate driving.

The baking temperature control system 31 includes a temperature sensor 32 that detects the temperature of the -11 low-temperature hot air region, and a temperature controller 33 that is integrally provided with a baking temperature setting device (not shown). Therefore, if a predetermined basic baking temperature is set on the setting device, a low temperature of 1゛l can be obtained from the relationship between the flow rates Qc1 and Qc2 regulated by the preset opening degree of the manual damper 19 and the temperature Th of high-temperature hot air. You can get hot air.

In addition, in the above, the temperature difference between low temperature rl and high temperature Th is 20
℃, one manual damper can be used as an automatically adjusting damper, and the low temperature TI can be automatically adjusted as a set value regardless of the value of high temperature h, or the temperature difference and high temperature can be adjusted automatically.
It can also be implemented by configuring that both the low temperature TI and the high temperature Th are automatically adjusted by setting T' h as a set value.

The flow control system 35 also controls the fan 1 of the hot air generator 10.
A temperature sensor 36 for detecting the temperature of the hot air in the downward blowing duct l-8 and a controller It is formed from a roller 37. This controller 37 is integrally provided with a temperature setting device.

Next, the effect will be explained.

First, a basic baking temperature of 160° C. is set in the setting device in the temperature controller 33 of the control means 30, and a complementary baking temperature, for example, 180° C. is set in the setting device in the controller 37.

At the start of baking, the hot air generator 10 is automatically started by a control device (not shown). The air inside the furnace body 1 is circulated through the circulation system 2.
Cycled through 0.

When the steady state is reached, the set baking temperature 1 is sent from the burner device 11.
Hot air with a temperature higher than 60°C by 20'C (180°C) is generated. The high temperature hot air is branched into ducts 12A and 12B.

The high-temperature hot air forced by the fan 17 is supplied to the high-temperature supply Tough 1
-22. High-temperature hot air is supplied to the lower blowing decks I-8, 8, passed through the duct 12A at the sewing part 15, and the circulation duct 2
Mixing with exhaust hot air of temperature Tc sent through 4,
Low-temperature hot air with a temperature of 160°C is generated. This low-temperature hot air is energized by the fan 14 and is supplied to the top blowing duct 6°6 through the low-temperature supply duct 21.

Here, low-temperature hot air is blown 4-5 from the upper blowing lower 7 to the side Ws of the workpiece W that has entered the baking area, and the lower blowing outlet 9 and the concentrated blowing means 3 are blown to the bottom Wb having a large heat capacity. High-temperature hot air is blown through the Therefore, baking 4 is started simultaneously on the side portion W s and the bottom portion wb at a predetermined baking temperature.

At this time, the concentrated blowing means 3 is configured to blow the high-temperature hot air from the lower air outlet 9 intensively onto a specific bottom part wb regardless of the movement of the trolley 2a, so that the bottom part wb can be quickly heated to a predetermined baking temperature. Can be baked upright.

The hot air in the upper low-temperature hot air area is exhausted from the suction duct 23° 23 to the circulation duct 24.

Then, while the workpiece W exists, the baking temperature control system 31
(32, 33), the hot air temperature TI in the low temperature hot air area on one side is stably maintained at the set basic baking temperature of 160°C. The hot air temperature T h of the lower high temperature hot air area is maintained at 180°C, which is 20°C higher. At this time, if there is a fluctuation in the temperature Th, the flow rate control system 35 (
36, 37) act to adjust the opening of the adjustment damper 18 to increase or decrease its energy and back it up.

As a result, the entire workpiece W is uniformly and stably baked at a predetermined baking temperature for a predetermined baking time, and a high-quality coating is completed.

According to this embodiment, the hot air from the lower air outlet 9 is concentratedly and efficiently blown onto a specific bottom part wb of the workpiece W via the concentrated blowing means 3 mounted on the trolley 2a. Because of this configuration, high-quality baking can be performed at a predetermined baking temperature and time, even on the bottom portion Wb, which has a large heat capacity or a thick coating film, regardless of the movement of the upward air flow 9 cart 2a (workpiece W) in the furnace.

In addition, the concentrated blowing means 3 connects an air guide port 3a corresponding to the lower air outlet 9, a blower port 3d facing the bottom wb, and an air guide path 3c communicating these 3a, 3d to the trolley 2a. Since it is integrally attached to the structure, the structure is simple, low cost, and thermal efficiency can be further increased.

Furthermore, the hot air generator 'It10 is formed to generate two types of hot air having different temperatures, and the hot air on the low temperature side is blown directly onto the side W S of the workpiece W from the upper blowing lower blower 7, and the hot air on the high temperature side is from the lower outlet 99 to the concentrated spraying means 3
Since the structure is such that the spray is directly applied to the bottom part wb through the
This eliminates problems such as overbaking, and enables high-quality baking of the entire workpiece by using the specified baking temperature and time.

Furthermore, the temperature TI of low-temperature hot air and the temperature of high-temperature hot air '1゛h
Since the configuration allows the settings to be changed arbitrarily, even if the heat capacity of the bottom part wb is large and the coating film thereof is thicker than that of the pond part, it can be sufficiently coped with and has a wide range of applicability. In addition, the hot air to the bottom part wb not only indirectly increases the supplied energy by increasing the amount of low-temperature hot air, but also directly establishes a predetermined baking temperature by supplying high energy held in a unit flow rate. Therefore, stable operation with high fS requirements is guaranteed without changing the hot air volume balance of the entire device, and handling is easy.

Furthermore, the hot air generator 10 generates high-temperature hot air with one burner device 11, and low-temperature hot air is generated by mixing high-temperature hot air and exhaust air, so the thermal efficiency is high and the equipment cost is low.

Furthermore, since the flow rate ratio between the amount of high-temperature hot air Qh and the amount of low-temperature hot air Ql is 1:9, the burner device! The heat capacity of No. 11 is small and low cost because it is only necessary to heat a small amount of low-temperature hot air to make high-temperature hot air.

Furthermore, since the baking temperature control system 31 of the control means 30 is a feedback control system that sets the low temperature rfX temperature TI, which is the basic baking temperature, to 1, it is possible to accurately and stably maintain the original baking temperature 1. I can do it. Since a flow rate control system 35 is also provided, it is possible to correct excess or deficiency in the absolute energy of the high temperature hot air by increasing or decreasing the flow rate while ensuring that the original baking temperature is maintained.From this point of view as well, the bottom part wb can be baked well. (Second Embodiment) This second embodiment is shown in FIG. In this embodiment, unlike the first embodiment, in which the entire workpiece W is baked with hot air blown directly from the upper blowing lower blower of the upper blowing duct 6.6, the heating ducts 6a and 6a are This is the case with a baking oven that uses radiant heat.

Therefore, since the concentrated spraying means 3 is the same as in the first embodiment, its explanation will be omitted.

Here, the heating duct 6a has almost the same structure as the above-mentioned double blow duct 6, but the blow ducts 23.
23 and extends to the ceiling, and the suction duct t-
23a is relatively small enough to exhaust the amount of hot air from each blowing port 3d, and is provided on the ceiling.

Further, the lower duct 1-8a and the blower outlet 9a are the same as the lower blower duct 1-8 and the lower blower outlet 9 of the first embodiment.

Note that in relation to the hot air generator 10 and the first control stage 30, the low temperature '1' should be set as high as necessary from the standpoint of radiation heating.

According to this second embodiment, the workpiece W is uniquely heated by radiation, and the bottom part wb is heated locally and intensively by the concentrated spraying means 3. Therefore, the same effects as in the first embodiment are achieved.

Incidentally, if one baking furnace uses a radiation heating method on the upstream side to prevent dust adhesion and uses a direct hot air blowing method on the downstream side, concentrated blowing stage 1 and stage 3 can be used as they are.

In the above embodiment, the air guide port 3a is arranged to correspond to the lower air outlet 9 in the horizontal direction, but it may also be arranged in a corresponding manner in the vertical direction. In addition, the air guide port 3
It is clear that the number and form of the guide pipes 3c, 3d and the openings 3d are not limited to those disclosed above.

[Effects of the Invention] The present invention has a structure in which a concentrated blowing means for guiding and blowing hot air from the blower [1] to the bottom of the workpiece, which is not connected to the hot air generator, is integrally provided on the cart. It is possible to avoid overbaking of the bottom part or incomplete baking of the bottom part, and to bake the whole body stably and reliably at the specified temperature and time, achieving a high quality coating, as well as having high thermal efficiency, easy handling, and great applicability. It is also possible to provide a baking oven for painting.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram showing the first embodiment of the present invention, Fig. 2 is a diagram showing the relationship between the concentrated spray means and the lower air outlet, and Fig. 3 is a configuration diagram of the main parts showing the second embodiment. and FIG. 4 are diagrams for explaining baking temperature mismatch in conventional painting baking furnaces. DESCRIPTION OF SYMBOLS 1...Furnace body, 2...Transporting means, 2a...Dolly, 3...Concentrated blowing means, 3a...Blowing port, 3c...Blowing path, 3d...Blowing port, 6a... Heating duct, 7... Upper outlet, 9... Lower outlet]] 9a... Outlet, 10... Hot air generator, 15... Mixing section, 20... Circulation System, 30...control means. Applicant: Trinity Industries Co., Ltd.

Claims (2)

[Claims] (1) In a painting baking furnace that includes a furnace body having a hot air generator, an upper outlet that blows the hot air guided from the hot air generator onto the side of the workpiece, and a lower outlet that blows the hot air to the bottom of the hot air generator. , the trolley for transporting the work is provided with an air guide port corresponding to the lower air outlet, and a blowing port corresponding to the bottom portion, and the air guide port and the blowing port are communicated within the cart. Baking furnace for painting. (2) In a painting baking furnace formed to include a furnace body having a hot air generator and a heating duct that radiantly heats a workpiece with the hot air guided from the hot air generator, the hot air guided from the hot air generator is inside the furnace body. An air outlet is provided for blowing the air onto the work, an air guide port corresponding to the air outlet is provided on a cart for transporting the work, and an air outlet is provided corresponding to the bottom of the work, and the air guide port and the air outlet are connected to each other. A baking furnace for painting, which is characterized by communicating within the carriage.