JPS6112800B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for burning off paint stuck to painted fixtures. Painting fixtures are widely used in various painting fields for the purpose of suspending and holding objects to be painted. Painting fixtures are usually connected to a conveyor and are painted with the object while holding it, and then subjected to a curing process, which causes the paint to stick and is extremely difficult to peel off and remove. . Conventionally, a combustion method has been put into practical use as a method for removing paint stuck to painted fixtures. However, in the conventional combustion method, the painted fixtures are directly combusted with a burner flame, which results in local heating and the painted fixtures become extremely hot locally, so when they come out of the combustion furnace and come into contact with the outside air, It is rapidly cooled and deforms. In order to improve the above drawbacks, there is a method of heating the entire painted fixture directly from the side.
Methods such as burning with flame from the bottom were tried, but
In either case, the conveyor or trolley that holds the painting tools is heated, which causes more damage to the equipment. The present invention provides a method and apparatus that eliminates thermal deformation of painted fixtures due to local heating, reduces heat transfer to conveyors, and efficiently burns off fixed paint. That is, the present invention provides a method for burning and removing stuck paint from painted fixtures, which comprises blowing a flame into a convection flame using an air flow, and igniting the entire surface of the stuck paint stuck to the painted fixture by the convection flame. and apparatus suitable for carrying out the same. In order to facilitate understanding of the present invention, the present invention will be explained with reference to FIG. FIG. 1 is a sketch of a specific example of an apparatus suitable for carrying out the method of the present invention. In the figure, 1 is a combustion furnace, 2 is a burner, 3 is an air inlet, 4 is a paint fixture (hanger), 5 is a conveyor, 6 is a ceiling,
7 indicates the floor and 8 indicates the flame shield (furnace wall). Flame is emitted from the burner 2 towards the painting tool 4. In the absence of air blowing, as in the conventional method, the painting fixture is directly heated and locally reaches a significantly high temperature. In the present invention, the convection flame is made into a laminar flow by the air blown in from the air inlet 3 (also serves as secondary combustion air). The air descends along the painting fixture 4, guides the flame emitted from the burner, and descends while caressing the painting fixture, passes through the floor 7, the shield 8, and the ceiling 6, and reaches the top of the painting fixture 4. Arrive. A convection flame is continuously formed in this path, and the painted fixtures are heated substantially uniformly and ignited without being locally heated. Although the shape and direction of the convection flame differ depending on the position of the air inlet and the burner, this does not essentially change the gist of the present invention. In the present invention, the preferred air blowing rate is about 580 Nm ³ /min or less per 1 m ² of air inlets. If a larger amount of air is blown in, the temperature inside the furnace will drop, and due to the drop in self-combustion temperature, the ignition of the fixed paint will be incomplete, resulting in a decrease in combustion efficiency and an unburned portion will remain. Of course, if a burner with a large combustion rate is used, the amount of air blown can be made larger than the above, but this is not practical. A suitable convective flame flow velocity for maintaining a substantially uniform combustion temperature and good overall ignition of the painted fixture is about 8 to 25 meters per second. The flow velocity of this convection flame is closely related to the heating temperature of the painted fixtures, and within the above range, the temperature and flow velocity have an approximately proportional relationship. When the flow velocity is out of the above range, convection is disrupted and localized heating or cooling begins to appear. A particularly suitable apparatus for carrying out the method of the present invention is a combustion furnace having an air inlet 5 in the center of the ceiling 6 and a pair of left and right burners 2 disposed outside the air inlet 5 as shown in FIG. Of course, there is also a method of arranging the air inlet and the burner at the bottom of the furnace, or a method of providing the air inlet on the outside of the burner, but since the flames will heat the conveyor 5, it is necessary to provide a separate means to prevent the conveyor from heating. There is the inconvenience of not having to do so.
Place the air inlet in the center of the ceiling (pathway for transporting painting supplies)
This eliminates the need for separate means for cooling the conveyor. This is a particularly preferred embodiment. The air gap width of the air inlet may be freely adjustable. Preferably, the burner is positioned and oriented such that the flame does not flow against the air flow. If it is installed opposite to the air flow, favorable convection will not be formed and there is a risk of fire extinguishment and incomplete combustion.
Most preferably, a pair of left and right parts are attached to the outside of the air inlet of the ceiling part 6 symmetrically with respect to the painting fixture. The burner outlet (nozzle) should be positioned at an angle of approximately 0 to 20 degrees to the vertical, or with its extended center axis between the top and bottom quarter of the fixture, depending on the shape of the fixture. It is appropriate to locate it. It is best to install it so that this angle can be changed arbitrarily. A preferred burner is a long flame burner. Flame shielding is essential to create convection. The shielding and the floor and/or ceiling may be rounded to effectively achieve convection. By using the method of the present invention, the painted fixtures are not locally heated and, therefore, are not deformed by heat at all, so that the cost of replacing painted fixtures can be significantly reduced. In addition, since the entire body is heated compared to conventional direct heating methods, the fixed paint is ignited more reliably, achieving complete combustion through self-combustion. Furthermore, the use of the top blow type has many advantages, such as avoiding heating of the conveyors and facilitating maintenance of the entire conveyor system. The present invention will be explained below by giving specific examples. The device used is shown in FIG. 1, and its detailed specifications are as follows. Burner: Long flame burner (combustion capacity 1
~20/hour, steam pressure and oil pressure 2-6Kg/
^cm2 , required air amount ^0.2m3 /min) Combustion furnace volume: 1000mm (height) x 600mm (width) x 1000mm
(Length) Air inlet slit width: 100mm Burner nozzle position and spray angle (α): 4 to 20
Variable temperature air blowing amount: ^560Nm3 /min (converted per ^m2 ) Blowing air temperature: 24 to 38℃ Test piece dimensions: 12mm (diameter) x 800mm (length) Fixed paint type: Alkyd resin paint Fixed paint thickness: 2750μ Conveyor speed: 100mm/min Processing time: 120 seconds The temperature and convection flame flow velocity at the positions shown in Figure 1 were measured under the following conditions. Table 1 shows the positions corresponding to the symbols in the figure. The position is expressed in mm as the distance (x) from the center line of the furnace and the distance (y) from the line indicating the ceiling (external) with respect to the cross-section of the furnace including the axis of the burner. Note that the ± symbol is omitted. Measurement was carried out using a remote thermocouple (150℃>, main thermocouple: copper-constantan) for medium temperature areas, and a remote thermocouple (1100℃, main thermocouple: platinum-rhodium) for high temperature areas, Rh = 10%. Ivy.

[Table] Furnace ceiling parts A, B, B', C and upper part of the furnace a,
Table 2 shows the temperature change over time at a'.

[Table] As is clear from the results in Table 2, even if the temperature of the upper parts a and a' of the furnace is heated to about 800°C, the temperature of the furnace ceiling is maintained below 70°C during the combustion of the objects to be treated. Therefore, there is no problem with damage caused by heat conduction in the ceiling of the furnace body, conveyor, or cart, which was a problem in the past. Furthermore, the temperature and flow velocity of the convective flame at positions a, b, c, d, e, f and the corresponding positions a', b', c', d', e', f' in the furnace were measured over time. . The temperature is shown in Figure 2, and the flow velocity of the convection flame is shown in Figure 3. In Fig. 2, the horizontal axis (x100°C) indicates temperature change, and the temperature decreases as you move from the center to the left and right. The vertical axis indicates the vertical position of each measurement position within the furnace, and corresponds to the measurement position shown in the center of the figure. From the top of Figure 2, 30 seconds after combustion ignition, 1
These are graphs taken after minutes, 1 minute 30 seconds, and 2 minutes. As is clear from FIG. 2, the temperature inside the furnace changes over time in a nearly symmetrical manner with respect to the test piece suspended in the center of the furnace, and the temperature at each measurement point changes successively. This is a feature of the method of the present invention, in which the flame emitted from the burner is not applied directly to the test piece, but is turned into a convection flame by the air flow blown from the upper part of the furnace body, and the convection flame is applied to the entire surface of the test piece. to ignite the adhered paint with substantially uniform heat transfer. In FIG. 3, the horizontal axis (m/sec) indicates the flow velocity of the convective flame, and the flow velocity decreases as one moves from the center to the left and right. As in FIG. 2, the vertical axis indicates the vertical position of each measurement position within the furnace, and corresponds to the measurement position shown in the center of the figure. These graphs were measured 30 seconds, 1 minute, 1 minute 30 seconds, and 2 minutes after combustion ignition from the top of FIG. 3, respectively. As is clear from FIG. 3, the flame flow velocity within the furnace changes over time almost symmetrically with respect to the center line of the furnace, and the flow velocity at each measurement point changes successively. The results shown in FIG. 3 also demonstrate the characteristics of the method of the present invention described above. The preferred convective flame flow velocity when carrying out the present invention is about 8 to 25
As already mentioned, it is expressed in m/sec and is approximately proportional to the heating temperature. Such a dense relationship between the heating temperature of the painted fixtures and the flow velocity of the convection flame in the furnace can be easily understood from a comparison of FIGS. 2 and 3.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a combustion furnace of a fixed paint combustion removal device. 1 is a combustion furnace, 2 is a burner, 3 is an air inlet, 4 is a paint fixture (hanger), 5 is a conveyor, 6 is a ceiling, 7 is a floor, and 8 is a flame shield (furnace wall). Also, A, B, C,...
Symbols such as , etc. indicate points at which temperature and/or flame velocity are measured during combustion of fixed paint. Figure 2 shows the change in temperature over time after ignition of the fixed paint at measurement points a, b, c, etc. shown in Figure 1. From the top, 30 seconds, 1 minute, and 1 minute, respectively. These are graphs after 30 seconds and 2 minutes. The horizontal axis represents the temperature (×100°C), and the vertical axis represents the vertical position of each measurement position. Figure 3 shows the change in flame flow velocity over time after ignition of the fixed paint at measurement points a, b, c, etc. shown in Figure 1. These are graphs after 30 minutes and 2 minutes. The horizontal axis represents the flow velocity (m/sec), and the vertical axis represents the vertical position of each measurement position.

Claims (1)

[Claims] 1. Combustion of fixed paint on painted fixtures, characterized by blowing a flame into a convection flame using an air flow, and igniting the entire surface of the fixed paint attached to the painted fixture by the convection flame. Removal method. 2 The amount of blown air per ^1m2 of air outlet, approx.
580Nm ³ /min or less The method according to item 1. 3. The first stage where the flow velocity of the convection flame is approximately 8 to 25 m/sec.
or the method described in paragraph 2. 4. The method according to any one of paragraphs 1 to 3, wherein the painting fixture is a paint hanger. 5. The method according to any one of paragraphs 1 to 3, wherein the painting fixture is a painting trolley. 6 Combustion furnaces equipped with one or more burners, blowers and air inlets in the ceiling and a flame shield along the direction of movement of painted fixtures, in which the descending flame emitted from the burners is A device for burning stuck paint on painted fixtures arranged to create a convection flame by means of an air flow from an inlet and a flame shield. 7. The device according to paragraph 6, wherein the air inlet is located in the center and the paired burners are arranged on the outside symmetrically with respect to the painting fixture. 8. The apparatus according to claim 7, wherein the injection shafts of the pair of burners are arranged to form an angle of 0 to 20 degrees with respect to the line of gravity of the furnace cross section including the shafts. 9 The size of the air inlet is determined by the amount of air blown in
9. The apparatus of any of clauses 6 to 8, wherein the apparatus is adjusted to a convective flame flow rate of about 8 to 25 m/sec or less, with a convective flame flow rate of about 580 Nm ³ /min per m ² or less. 10. The device according to any one of items 6 to 9, wherein the flame shield forms a radius with the ceiling and/or the floor. 11. The apparatus according to any one of paragraphs 6 to 10, wherein the painting fixture is a paint hanger. 12. The device according to any one of paragraphs 6 to 11, wherein the painting tool is a painting trolley.