JPH0221756Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an improvement of an infrared firing furnace which has a relatively high internal temperature of 900°C to 1000°C for firing ceramic printed circuit boards and the like.

(Conventional technology) Conventional infrared firing furnaces of this type have low internal temperatures.
Because a clean atmosphere at high temperatures of 900℃ to 1000℃ is required, an infrared cylindrical heating element is installed in the ceiling and bottom of the furnace, with a heating wire housed in a quartz tube with a small coefficient of thermal expansion and excellent oxidation resistance. It is known that a large number of these are arranged in the furnace width direction of the furnace body. (For example, Japanese Utility Model Application Publication No. 59-55395) (Problems to be solved by the invention) However, such an infrared firing furnace cannot control the temperature division in the length direction of the infrared cylindrical heating element used, so As the temperature decreases due to heat dissipation into the outside air, the effective length of the infrared cylindrical heating element must be larger than the width of the object to be fired, that is, the belt width, which not only increases the furnace width but also increases the electric capacity. The problem was that it became uneconomical as it grew larger.

(Means for solving the problems) The present invention was completed with the aim of creating an infrared firing furnace with good temperature distribution that solved the problems mentioned above. A large number of infrared cylindrical heating elements extending in the width direction of the furnace body are disposed in the furnace body extending from the furnace body to the outlet side, and are formed on the inner side of the opposing side walls of the furnace body so as to protrude at right angles from both ends. The present invention is characterized in that an infrared cylindrical heating element for temperature drop compensation extending in the longitudinal direction of the furnace is attached to the side wall 1a with adjustable mounting legs 8e, 8e.

(Example) Next, the present invention will be described in detail with reference to the illustrated embodiment. 1 is a firing furnace body made of a heat insulating material such as fireproof insulation bricks and high temperature refractory fibers; A large number of infrared cylindrical heating elements 2 are arranged in parallel at regular intervals on the ceiling and bottom of the furnace body 1, extending in the width direction of the furnace body 1, that is, in a direction orthogonal to the conveying direction. The infrared cylindrical heating element 2 is made of a ceramic material such as alumina porcelain, etc., which has excellent oxidation resistance and is wrapped with a high-temperature resistance heating element 2c such as a coiled iron or chrome wire suitable for high temperatures. A rod-shaped or tubular heat-resistant core material 2b is loosely inserted into a quartz tube 2a, which has small thermal expansion and excellent oxidation resistance, and both ends of the rod-shaped or tubular heat-resistant core material 2b are filled into both end portions of the quartz tube 2a. Insulating cushioning material 2d such as fireproof fiber,
2d supports the heat-resistant core material 2b so that it is eccentric to the center or above the quartz tube 2a. Moreover, this infrared cylindrical heating element 2, which is slightly longer than the furnace width of the furnace body 1, has both ends connected to the furnace body 1.
The insertion holes 3 are arranged in a straight line in the upper part of each side wall 1a facing each other, and the insertion holes 3 are arranged in a straight line in the lower part of both side walls 1a so as to be located below between the insertion holes 3, 3. side walls 1 so that they are inserted into the furnace ceiling and bottom in a staggered manner.
The projecting end is fixed to a holder 4 which is installed in parallel between the side walls 1a and 1a and attached to the outer surface of each side wall 1a. Furthermore, the high-temperature resistance heating element 2c wound around the heat-resistant core material 2b is designed so that its effective heat generation length is approximately equal to the width inside the furnace in order to improve the temperature distribution inside the furnace as much as possible. The ends of the lead wires are led out from both ends of the quartz tube 2a, and the lead wires of the upper and lower infrared cylindrical heating elements 2 are connected.
It consists of two heater circuits. In addition, quartz tube 2
a, heat-resistant core material 2b and high-temperature resistance heating element 2
c. The bulk heat insulating buffer material 2d is not fixed by adhesive, but can be inserted and removed individually from outside the furnace by removing the bulk heat insulating buffer material 2d. Reference numeral 5 denotes an endless net conveyor type conveyor path for conveying the products to be fired, which is provided from the inlet side to the outlet side of the furnace body 1, and is made of a nickel-chromium alloy with excellent heat resistance and oxidation resistance. An endless belt-like net 5a made of wires or the like is placed on a refractory support 6 disposed at the bottom of the furnace so that its upper end is located slightly above the infrared cylindrical heating element 2. It is assumed to be slid on a guide quartz tube 7 extending in the furnace length direction. 8 is the infrared cylindrical heating element 2 located inside the opposing side walls 1a, 1a in the furnace body 1.
An infrared cylindrical heating element for temperature drop compensation extending in the direction perpendicular to the side wall 1a, that is, along the furnace length direction, and the infrared cylindrical heating element 8 is also similar to the infrared cylindrical heating element 2. Although the configuration is substantially the same, mounting legs 8e, 8e made of quartz tubes are welded to both ends of the quartz tube 8a at right angles from the quartz tube 8a, and the ends of the lead wires are connected to each end of the quartz tube 8a. is led out to the outside, and this infrared cylindrical heating element 8 is inserted into a vertically elongated insertion hole 9 provided in a heat insulating block 9 that is removably fitted into a stepped hole provided in the side wall 1a.
a with mounting legs 8e, 8e, and is attached to the side wall 1a so that it can be attached to and detached from the side wall 1a and its position can be freely adjusted in the vertical and longitudinal directions. Reference numeral 10 denotes a temperature detection end made of a thermoelectric material such as alumel-chromel. The temperature detection end 10 is inserted into the furnace from the ceiling of the furnace body 1, and is connected to a temperature controller to turn on the heater. Maintain the appropriate temperature according to the purpose of use. In addition,
In the figure, 11 is a drying furnace provided at the lower part of the furnace 1, 12 is a conveyance path for the drying furnace 11, and 13 is a fired product 2 conveyed to the outlet side of the drying furnace 11.
1 onto the conveyance path 5 on the entrance side of the firing furnace body 1; 14 and 15 are the firing furnace bodies 1;
conveyance path cleaning device and drying device installed on the exit side of the
16 and 17 are rollers of the conveyance paths 5 and 12, and 18 is a square disk-shaped far-infrared radiation heater disposed on the ceiling of the drying furnace body 11.

(Function) With this configuration, when the article to be fired 21 placed on the conveyance path 5 for conveying the article to be fired is sent into the furnace body 1 for firing, the article to be fired 21 is transferred to the furnace body 1.
In addition to being heated by radiant heat from infrared cylindrical heating elements 2 extending in the width direction of the furnace body 1, which are arranged in large numbers inside the furnace body 1, it is heated by the radiant heat from the infrared cylindrical heating elements 2 disposed inside the furnace body 1, and is placed along each side wall 1a at an inside position of the opposing side walls 1a, 1a of the furnace body 1. The product to be fired 21 is uniformly heated by auxiliary radiation heating from an infrared cylindrical heating element 8 disposed in the longitudinal direction of the furnace.
When the temperature inside the furnace is set to 1000°C, the temperature difference between the center and the edge directly above the conveyance path 5 is ±7.5 when there is no infrared cylindrical heating element 8 along the side walls 1a, 1a.
℃, but by installing the infrared cylindrical heating element 8 to compensate for the temperature drop, the temperature has been improved to ±1℃.The temperature distribution is good, so the width of the furnace can be kept to a minimum, and the electric It is economical because the capacity can be reduced. Moreover, since the infrared cylindrical heating element 8 extends in the furnace length direction, the temperature drop in the portion along the side walls 1a, 1a inside the furnace body 1 can be compensated for with a small number of installations, and the installation process can be simplified. There is also. Furthermore, since the high-temperature resistance heating element 2c is wrapped around the heat-resistant core material 2b and completely housed within the quartz tube 2a, even if the temperature reaches 1000°C or higher, the quartz tube
There is no deformation of the infrared cylindrical heating element 2 due to the thermal deformation of a or the weight of the high-temperature resistance heating element 2c, and the irradiation distance to the fired product 21 does not become uneven due to deformation, so the temperature distribution in the furnace is maintained. Furthermore, the phenomenon of falling oxides, etc., which is observed in heaters with exposed heating elements, is eliminated, and a clean atmosphere can be created in the furnace. In addition, if the infrared cylindrical heating element 8 is attached to each side wall 1a so that its position can be adjusted as in this embodiment, the insertion position can be adjusted from outside the furnace, and the temperature distribution inside the furnace can be finely adjusted. In addition, if the infrared cylindrical heating element 8 is inserted into the heat insulating block 9 and the heat insulating block 9 is made detachable from the stepped hole, when the infrared cylindrical heating element 8 is replaced, the furnace body It can be easily replaced from outside the furnace in a short time without disassembling the infrared cylindrical heating element 1, and the quartz tube of the infrared cylindrical heating element 2, 8, high temperature resistance heating element, heat resistant core material, and bulk insulation. If the cushioning material is not fixed with adhesive, only the high-temperature resistance heating element needs to be replaced in the event of heater breakage, resulting in economical maintenance costs.

(Effect of the invention) As is clear from the above description, the present invention provides temperature reduction that extends in the furnace length direction along the side wall of the furnace body in which a large number of infrared cylindrical heating elements are arranged extending in the furnace width direction. The provision of a compensating infrared cylindrical heating element improves the temperature distribution within the furnace, and it is extremely economical, minimizing the width of the furnace and reducing the electric capacity, compared to conventional infrared rays of this type. It is of great practical value as it solves the problems of firing furnaces.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing an embodiment of the present invention, Fig. 2 is a partially cutaway front view of the main part, and Fig.
The figure is also a partially cutaway side view of the main part. 1: Furnace body, 1a: Side wall, 2: Infrared cylindrical heating element extending in the furnace width direction, 5: Conveyance path, 8: Infrared cylindrical heating element for temperature drop compensation extending in the furnace length direction, 8
e: Mounting leg.

Claims (1)

[Scope of utility model registration request] A large number of infrared cylindrical heating elements 2 extending in the furnace width direction of the furnace body 1 are disposed within the furnace body 1 in which a transfer furnace 5 for transferring the products to be fired is provided from the inlet side to the outlet side. A temperature drop compensating device extending in the furnace length direction is attached to the side wall 1a so that its position can be adjusted freely, with mounting legs 8e, 8e formed at right angles on both ends of the inner side of the opposing side walls 1a, 1a. An infrared firing furnace characterized by disposing an infrared cylindrical heating element 8.