JPS6249685B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an energy-saving coated wire baking furnace.

As is well known, the baking furnace for painted electric wires such as enameled wires is equipped with a circulation fan that circulates hot air inside the furnace, and the insulating paint attached to the electric wire is dried and hardened by the hot air. Volatile combustible gases such as solvents contained therein are passed through a catalyst layer placed at an appropriate position in the furnace to undergo chemical changes such as combustion, and the reaction heat generated at this time is given to the circulating hot air. We are trying to use heat effectively. 1st
The figure is a vertical cross-sectional view of a vertical baking furnace, showing one example.
1 is a vertically long furnace body surrounded by an insulated furnace wall; 2 is a painted electric wire that moves at a predetermined speed within the furnace from an inlet 3 at the bottom to an outlet 4 at the top; 5 is the outlet 4
This is an air cooling tower that extends above the building.
Inside the furnace, hot air is circulated by driving the circulation fan 6 as shown by the missing marks. That is, the hot air sent out from the circulation fan 6 branches into the ventilation path 7 and the ventilation path 8, goes toward the exit 4 direction and the inlet 3 direction, and is blown into the evaporation zone A and the hardening zone B from below and above, respectively. Then, it is discharged from the circulation duct 11 connected to the intermediate portion, passes through the catalyst layer 12, and is sucked into the circulation fan 6. The catalyst layer 12 promotes combustion of combustible gas as described above. Note that the electric heating element (preheater) 13 provided in the front part of the catalyst layer 12 is energized for preheating at the start of operation. Moreover, 14 is an electric heating body (after heater) provided in the ventilation path 7. Reference numerals 15a and 15b are openings and dampers for blowing out a portion of the hot air passing through the ventilation path 8 to the evaporation zone A. Reference numeral 9 denotes a breather box provided outside the outlet 4. Air is forced into the breather box through an air supply pipe 10 to balance the pressure inside the furnace and offset the draft effect in the vertical baking furnace. I have to. Further, 21 is an outside air intake port, and 22 is an exhaust port, which are opened/closed and whose opening degree is adjusted as necessary.

As described above, the electric wire 2 to which the insulating paint is applied by a coating device (not shown) enters the furnace from the inlet 3 and receives hot air and the evaporation zone A.
The solvent is evaporated by the radiant heat of the electric heating element 16 installed in the heating element 16, and then the paint is baked by high-temperature hot air from above by passing through the curing zone B. In conventional coated wire baking furnaces, if the wires were heated only with hot air in the evaporation zone A, the paint attached to the wires would dry from the surface, so it is necessary to dry the paint from the inside. It was necessary to provide the electric heating element 16 so that the radiant heat could be obtained. In addition, in order to obtain a good coating finish, it is necessary to set the temperature inside the furnace so that it gradually increases from the inlet 3 to the outlet 4, so the electric heating element (after heater) is used to increase the temperature of the hot air blown into the curing zone B. The electricity consumption was large, as it sometimes required 14 hours.

However, in view of the recent demand for a reduction in energy costs and the need to achieve even greater energy savings, the present invention aims to provide a painted electric wire baking furnace that can meet these demands.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 5. Note that the same reference numerals as in FIG. 1 indicate the same or corresponding parts, so a detailed explanation thereof may be omitted.

To explain the embodiment shown in FIG. 2, in this baking furnace, a matzuru 17 made of a heat-resistant metal tube is provided in the furnace so as to cover the painted electric wire 2.
The hot air coming out of the circulation fan 6 is guided downward along the longitudinal direction of the Matsufuru 17 through the furnace space 18 around the outer periphery of the Matsufuru 17. A part of the hot air coming out of the fan 6 is guided into the Matsufuru 17 through the opening 19 near the outlet 4, while the hot air that has descended through the furnace space 18 is guided into the Matsufuru 17 through the opening 20 near the inlet 3. I'm trying to make a U-turn.
Reference numeral 11 denotes a circulation duct connected approximately to the middle of the matsufuru 17. Hot air from the matsufuru 17 is discharged through the circulation duct, passes through the catalyst layer 12, and is sucked into the circulation fan 6. A portion of the hot air blown from the circulation fan 6 enters the Matsufuru 17 through the opening 19 and flows through the Matsufuru 17 into the circulation duct 1.
Flows in one direction. 23 is a damper provided in the opening 19, 24 is a damper provided in the furnace space 18, and by adjusting the opening degrees of these dampers, the respective amounts of hot air are adjusted.

In the painted electric wire baking furnace configured in this way, the high temperature hot air sent out from the circulation fan 6 heats the matsufuru 17 from the outside, so that radiant heat is radiated from the inner circumferential surface of the matsufuru 17 to the painted electric wire 2. The hot air that has descended through the furnace space 18 makes a U-turn through the opening 20, enters the matsufuru 17, dries the painted electric wires, rises, and is sucked into the circulation duct 11 together with the solvent vapor. In this way, in this baking furnace, in the evaporation zone 9, the hot air flow inside the pine ful 17 and the hot air flow around the outer periphery of the pine ful 17 flow in opposite directions (counterflow type).

Another embodiment of the present invention shown in FIG. 3 is an improved version of the baking furnace shown in FIG. 2 so that the temperature can be adjusted individually for each zone. That is, when the hot air descends, a bypass duct 25 is created in the middle of the furnace space 18.
The bypass duct 25 is connected to the suction side of the circulation fan 6, and the bypass duct 25 is provided with a damper 26. Further, a ventilation passage 27 is formed on the outer periphery of the Matsufuru 17 near the outlet 4 for raising high-temperature hot air blown from the circulation fan 6 along the outer periphery of the Matsufuru 17, and a damper 28 is also provided in the ventilation passage. Note that BU1 is a burner provided in the front part of the catalyst layer 12. Fig. 4 shows the temperature control system of the baking furnace shown in Fig. 3. In the figure, BL1 to BL3 are blowers, thick lines extending from each blower to the furnace body side are air supply pipes, and T1 to T5 are air supply pipes at various locations in the furnace. Thermocouple to measure temperature, TC1 to TC5 are temperature controllers, CM1 to CM
7 is a control motor, Bu1 is a burner, and FU is its fuel supply pipe. The blower BL1 sends air to the pressure box 9 with its air supply amount adjusted under the control of a control motor CM1 which is movable in response to a command from TC1. In addition, the blower BL2 supplies air (atmosphere) to the inlet 3 of the furnace space 18, the rear of the catalyst layer 12, and the front of the catalyst layer 12 under the control of the control motors CM4, CM5, and CM7, causing the hot air temperature to rise excessively. I'm trying to keep it in check. When the burner BU1 starts operating, combustion air is supplied from the blower BL3 to burn the fuel and raise the temperature inside the furnace. The control motor CM2 automatically adjusts the opening degree of the damper 26, and the control motor CM3 automatically adjusts the opening degree of the damper 23. Note that the damper 28 can be manually adjusted in this case.

In the painted electric wire baking furnace configured as described above, by adjusting the damper 26 of the bypass duct 25, part or most of the hot air descending in the furnace space 18 can be returned to the suction side of the circulation fan 6 midway. can.

By adopting such a configuration, as shown in the temperature curve of Fig. 5, from evaporation zone A to hardening zone B,
This enables ideal control to gradually increase the temperature. That is, in the evaporation zone A, the provision of the bypass duct 25 prevents a drop in temperature inside the matsufuru 17, and the temperature can be increased as it moves upward. In addition, as mentioned above, by appropriately supplying cold air to the position near the entrance 3 of the furnace space 18 using the blower BL2, the temperature inside the Matsufuru 17 near the entrance 3 of the evaporation zone A can be suppressed to a low level. There is no possibility that air bubbles will be generated in the coating film due to sudden heating of the electric wire 2.

As mentioned above, the sole purpose of the conventional pressure box 9 was to prevent hot air from being discharged due to the draft effect inside the furnace. By aggressively supplying the cold air or hot air into the furnace, it is possible to control the temperature of the hardening zone inside the furnace, and the direction of travel of the cold or hot air wires blowing into the furnace can be controlled. Since it is oriented in the opposite direction, it also has the effect of blowing off the solvent vapor that adheres to the wire and rises.It not only functions as a conventional pressure box, but also functions as a temperature control and solvent vapor removal function. can do.

As described above in the embodiments, the painted electric wire baking furnace of the present invention is provided with a matsufuru in the furnace so that the combustion air flows in one direction along the longitudinal direction of the matsufuru through the inner space of the furnace around the outer circumference of the matsufuru. At the same time, the hot air is made to make a U-turn into the Matsuful near the end of the furnace, and the hot air flow inside the Matsuful and the hot air flow around the outer circumference of the Matsuful are counterflow type, so the thermal energy of the hot air is transferred to the Matsuful. Heat can be efficiently transferred to the coated electric wires inside, and therefore running costs such as power consumption can be significantly reduced without the need for an auxiliary heat source. Moreover, by employing the Matsufuru coating, radiant heat can be radiated to the coated wire, thereby eliminating various problems such as the generation of bubbles caused by the paint layer drying from the surface first. In addition, temperature can be easily controlled by adjusting the damper installed in the furnace space and the ventilation volume of the bypass duct connected to the furnace space, so it can meet a wide range of needs and provide high quality products. It is very useful industrially, as painted electric wires can be produced.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an example of a conventional painted electric wire baking furnace, Fig. 2 is a longitudinal sectional view of a painted electric wire baking furnace showing one embodiment of the present invention, and Fig. 3 is a longitudinal sectional view showing another embodiment. 4 is a temperature control system diagram of the painted electric wire baking furnace of FIG. 3, and FIG. 5 is a diagram showing an example of the temperature curve of the painted electric wire baking furnace of FIG. 3. 1...Furnace body, 2...Painted electric wire, 3...Inlet, 4
...Outlet, 6...Circulation fan, 11...Circulation duct, 12...Catalyst layer, 17...Matsuful, 18...
... Furnace space, 19, 20... Opening, 24... Damper provided in the furnace space, 25... Bypass duct, 26... Damper provided in the bypass duct.

Claims (1)

[Claims] 1. A circulation fan is provided that circulates hot air in the furnace, and the hot air dries and hardens the insulating paint attached to the wires, and also passes the flammable gas volatilized from the insulating paint to the catalyst layer. It is a painted electric wire baking furnace in which chemical changes such as combustion are caused by direct combustion with a direct flame burner, and the reaction heat generated at that time is given to the circulating hot air. A Matsuful is provided, and the hot air is guided to flow in one direction along the longitudinal direction of the Matsuful in the furnace space around the outer circumference of the Matsuful, and the hot air is made to make a U-turn into the Matsuful near the end of the furnace. 1. A painted electric wire baking furnace characterized in that the hot air flow of the matsufuru and the hot air flow of the outer periphery of the matsufuru are of a counterflow type. 2. Claim 1, wherein a circulation duct for discharging the hot air inside the Matsuful is connected to approximately the middle of the Matsuful, and the hot air is made to make a U-turn into the Matsuful at both ends of the Matsuful. Painted electric wire baking furnace described in . 3. The painted electric wire baking furnace according to claim 1 or 2, further comprising a damper for adjusting the flow of hot air in the furnace space around the outer periphery of the matsufuru. 4. A method according to claim 1, 2, or 3, wherein a bypass duct is provided in the furnace space around the outer periphery of the Matsufuru for discharging the hot air for circulation, and a damper is provided in the bypass duct. Painted wire baking furnace.