JP2006132921A - Continuous heat treatment furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous heat treatment furnace capable of making the transporting speed of objects to be thermally treated in a firing area higher than that of objects to be thermally treated in a drying and binder-removing area. <P>SOLUTION: The drying and binder-removing area 21 where drying of the objects 1 to be thermally treated and/or removal of binder are carried out and the firing area 23 where the objects 1 to be thermally treated are fired are disposed in succession from inlet side towards outlet side of the furnace, and the objects 1 to be thermally treated are subjected to drying and/or removal of binder while being transported through the drying and binder-removing area 21 and thereafter are fired while being transported through the firing area 23. The heat treatment furnace has at least two transporting mechanisms disposed along the transporting direction of the objects 1, the objects 1 are transported by different transporting mechanisms in the drying and binder-removing area 21 and the firing area 23, respectively, and each transporting mechanism is set so that the transporting speed in the drying and binder-removing area 21 and the transporting speed in the firing area 23 differ from each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a continuous heat treatment furnace used for heat treatment of solar cell substrates and the like.

  In the production of solar cell substrates, conductive electrode paste is printed and formed in a predetermined pattern on the front and back surfaces of the substrate, and then heat treatment (debinder / There is a process of drying and baking. Usually, in a heat treatment furnace used for such heat treatment, a drying / debinding region for drying and / or debinding the material to be heat-treated from the inlet side to the outlet side of the furnace, and firing the material to be heat-treated And a baking region for performing the heat treatment are dried and / or debindered while being transported through the drying / debinding region, and then fired while being transported through the firing region. It is carried out.

  As a transport mechanism for transporting an object to be heat treated in a heat treatment furnace, a mesh belt conveyor is widely used when the object to be heat treated is a solar cell substrate (see, for example, Patent Document 1). Recently, the heat capacity is smaller than that of mesh belt conveyors, and rapid heating and cooling is possible. Therefore, tension is applied to the walking beam and wire such as wire, and the wire is like a walking beam. A transport mechanism that performs a transport operation is also being used (see, for example, Patent Document 2).

By the way, in the conventional continuous heat treatment furnace used for the above-mentioned purposes, the drying and / or debinding region and the firing region are transported at the same speed by one type of transport mechanism while drying and / or drying the material to be heat treated. Or it had the structure which performs a series of heat processing called a binder removal process and baking. However, the drying after the drying and / or debinding treatment on the solar cell substrate, that is, the baking of the conductive paste made of aluminum or silver onto the substrate surface is rapidly heated to about 800 ° C. in a short time and then rapidly cooled. Therefore, in order to achieve this ideal firing state, it is necessary to cover the material in the firing region rather than the conveyance speed of the material to be heat treated in the drying / debinding region. It is required to increase the conveyance speed of the heat-treated product and to quickly pass through the firing region maintained at a high temperature of 1000 ° C. or higher in a short time.
JP 2002-203888 A No. 7-4470

  The present invention has been made in view of such conventional circumstances, and the object of the present invention is to make the conveyance speed of the heat-treated material in the firing region higher than the conveyance speed of the heat-treated material in the drying / debinding region. It is an object of the present invention to provide a continuous heat treatment furnace that can be made faster.

  According to the present invention, from the inlet side to the outlet side of the furnace, at least one drying / debinding region that performs drying and / or debinding treatment of the object to be heat treated, and a firing region that performs firing of the object to be heat treated Are provided in order, and after the material to be heat-treated is dried and / or debindered while being transported through the drying / debinding region, it is fired while being transported through the firing region, As a transport mechanism for transporting the object to be heat-treated, it has at least two transport mechanisms arranged along the transport direction of the object to be heat-treated, and each of the drying / debinding area and the firing area is separately provided. The material to be heat-treated is transported by the transport mechanism, and the transport speed in the drying / debinding region and the transport speed in the baking region are as follows. DOO continuous type heat treatment furnace conveying speed is set for each transport mechanism so that the different transport speed, is provided.

  The continuous heat treatment furnace of the present invention is configured so that the object to be heat-treated is conveyed by a separate conveying mechanism in the drying / debinding region and the firing region, and the conveying speeds of these conveying mechanisms are set to be different. Thus, it becomes possible to make the conveyance speed of the object to be heat-treated in the drying / debinding region different from the conveyance speed of the object to be heat-treated in the baking region. And, if the conveyance speed of the heat treatment object in the firing region is set to be faster than the conveyance speed of the heat treatment object in the drying / debinding area, the heat treatment object passes through the firing area quickly in a short time, Since the object to be heat-treated can be rapidly heated and cooled, an ideal drying / firing curve can be obtained in the heat treatment of the solar cell substrate and the like, and a product having good characteristics can be manufactured.

  As described above, the continuous heat treatment furnace of the present invention includes at least one drying / debinding region for drying and / or debinding the heat-treated material from the furnace inlet side to the outlet side, and the heat-treated material. And a firing region for performing the firing in order, and after the material to be heat-treated is dried and / or debindered while being transported through the drying / debinding region, it is fired while being transported through the firing region. A heat treatment furnace having at least two transfer mechanisms arranged along a transfer direction of the heat treatment object as a transfer mechanism for transferring the heat treatment object, the drying / debinding region and the baking In the area, the heat treatment object is conveyed by the separate conveyance mechanisms, and the conveyance speed and the front in the drying / debinding area are Wherein as the conveying speed in the firing area is different from the conveying speed in which the transport speed of the transport mechanism is set.

  Hereinafter, representative embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and is within the scope of the present invention. It should be understood that design changes, improvements, and the like can be made as appropriate based on the general knowledge of vendors.

  FIG. 1 is a schematic explanatory view showing an example of an embodiment of a continuous heat treatment furnace according to the present invention. As described above, the continuous heat treatment furnace of the present invention includes a drying / debinding region 21 for drying and / or debinding the heat-treated object 1 from the inlet 31 side to the outlet 32 side of the furnace, and the heat treatment. A firing region 23 for firing the product 1 is provided in order, and the material to be heat-treated 1 is dried and / or debindered while being transported through the drying / debinding region 21 and then fired while being transported through the firing region 23. As a transport mechanism for transporting the object to be heat treated 1 in the furnace, it has two kinds of transport mechanisms. In the present invention, the “debinding process” refers to a process for removing the binder component contained in the object to be heat-treated by heating.

  In the present embodiment, one of the two types of transport mechanisms operates a wire 2 stretched in the furnace length direction to operate the first heat-treated object 1 placed on the wire 2. It is a transport mechanism, and in the drying / debinding area 21, the workpiece 1 is transported by the first transport mechanism. The other of the two types of transport mechanisms is a second transport mechanism that transports the workpiece 1 placed on the beam 6 by operating the beam 6. The workpiece 1 is transported by the second transport mechanism. In this example, a wire is used for the first transport mechanism and a beam is used for the second transport mechanism. However, instead of the wire of the first transport mechanism, a beam or a chain may be used. Instead of the beam of the transport mechanism, a wire or a chain may be used.

  For example, when the object to be heat-treated 1 is a rectangular solar cell substrate having a side of about 15 cm, the length of the drying / debinding region 21 is about 2 m and the length of the firing region 23 is about 0.3 m. Is preferred. The drying / debinding area 21 is adjusted to an atmospheric temperature of about 300 to 500 ° C. by a heating means such as an Infrastein (IR) heater 11 provided in the furnace ceiling, and the firing area 23 includes the furnace ceiling and the furnace. It is desirable that the ambient temperature is adjusted to about 1000 ° C. by a heating means such as a near infrared lamp heater 12 provided on the floor. The drying / debinding region may be configured as one region as shown in FIG. 1 or may be configured to be divided into a plurality of drying / debinding regions.

  In addition, as shown in FIG. 1, a buffer region 22 may be provided between the drying / debinding region 21 and the baking region 23 to alleviate the thermal effect that one of these regions receives from the other. The front end portion and the rear end portion of the buffer region 22 are provided with partition walls 13 that narrow the cross-sectional area of the portion through which the object to be heat-treated 1 passes, and the drying / debinding region 21 and the firing region before and after the buffer region 22 It is preferable to prevent heat transfer between the two.

  For the first transport mechanism, instead of the beam (columnar member) in the conventional walking beam, it is also possible to use a wire rod or chain stretched in the furnace length direction by applying a tension that can support the object to be heat treated. It was devised based on the idea that there are two kinds of wire rods arranged at predetermined intervals so as to perform different operations with respect to the continuous heat treatment furnace, such as a so-called double walking beam, or It may consist of a chain or, like a general walking beam, two types arranged at predetermined intervals so that one is fixed to the heat treatment furnace and the other moves relative to the heat treatment furnace. You may consist of a wire or a chain.

  FIG. 2 is a schematic explanatory diagram illustrating an example of an embodiment of the first transport mechanism. The first transport mechanism transports the object to be heat-treated placed on the wire, beam or chain by operating the wire, beam or chain stretched in the furnace length direction. Then, the example at the time of using a wire is demonstrated. In this example, the first transport mechanism has two types of wires, a first wire 2a and a second wire 2b, each composed of two wires. The end of the first wire 2a is fixed to the first wire holder 3a. Since the end of the first wire 2a is fixed to the first wire holder 3a via the winding spring 4a, the same tension is always applied to the first wire 2a. Similarly, the end of the second wire 2b is fixed to the second wire holder 3b via the winding spring 4b, and the same tension is always applied. In FIG. 2, one end of the first wire 2a and the second wire 2b is omitted, but the end on the omitted side is similarly fixed to the first wire holder or the second wire holder. Has been.

  As shown in FIG. 1, the first wire holder 3a and the second wire holder 3b are fixed to a first support 5a and a second support 5b, respectively. The first support 5a is configured to periodically repeat the ascending, advancing, descending, and retreating operations with a fixed movement stroke by a driving mechanism (not shown), whereby the first wire 2a is similar. Perform periodic operation. The second support 5b is configured to periodically repeat the forward and backward movements with a constant movement stroke by a drive mechanism (not shown), whereby the second wire 2b also has the same periodicity. Perform the action.

  In this transport mechanism, first, the first wire 2a is in a lowered state. At this time, the object to be heat-treated 1 is placed on the second wire 2b. Next, the second wire 2b moves forward by a predetermined stroke, while the first wire 2a moves backward by a predetermined stroke while descending. Subsequently, the first wire 2a rises by a predetermined stroke, and the heat-treated object 1 is transferred from the second wire 2b onto the first wire 2a in the course of this rise. Next, the first wire 2a moves upward by a predetermined stroke while being raised, while the second wire 2b moves backward by a predetermined stroke. Finally, the first wire 2a is lowered, and in this descending process, the object to be heat-treated 1 is transferred from the first wire 2a onto the second wire 2b, and each wire returns to its original position. This conveyance mechanism can convey a to-be-processed object because each wire repeats these operation | movement.

  In addition, the conveyance operation of the wire in the first conveyance mechanism is not limited to this. For example, in the above example, the second wire 2b is fixed to the continuous heat treatment furnace, and the first wire Only 2a may operate as described above. In this case, first, the heat-treated object 1 placed on the second wire 2b is transferred onto the first wire 2a when the first wire 2a rises. Next, the 1st wire 2a advances and the to-be-processed object 1 is conveyed forward. Further, when the first wire 2a is lowered, the workpiece 1 is transferred onto the second wire 2b. Finally, the first wire 2a moves backward and returns to the initial position. This transport mechanism can transport the object to be heat-treated by the second wire 2b repeating the above operation even if the first wire 2a does not operate.

  FIG. 3 is a schematic explanatory diagram illustrating an example of an embodiment of the second transport mechanism. The second transport mechanism transports the object to be heat-treated placed on the beam, wire, or chain by operating the beam, wire, or chain. In this example, a beam is used. An example will be described. In this example, the second transport mechanism includes an elevating drive device 8 that raises and lowers the lifter 7, a beam drive device 10 that moves the beam 6 attached to the lifter 7 in the front-rear direction, and the elevating drive device 8 itself. And a horizontal movement device 9 that horizontally moves in the front-rear direction. With these devices, the beam 6 periodically repeats the operations of ascending, advancing, descending, and retreating with a constant movement stroke with respect to the continuous heat treatment furnace. Be able to.

  FIG. 4A to FIG. 4E are schematic explanatory views showing an operation in which the second transport mechanism receives the heat-treated material from the first transport mechanism and transports the inside of the firing region. . First, as shown in FIG. 4 (a), the beam 6 is in a lowered state, and as shown in FIG. 4 (b), the object to be heat-treated 1 is moved to the front of the firing region 23 by the first transport mechanism. It starts to rise when it is transported. During the ascending process, the object to be heat-treated 1 is transferred onto the beam 6 from the wire 2 of the first transport mechanism. Next, as shown in FIG. 4 (c), the beam 6 moves upward while moving upward, and by this forward movement, the object to be heat-treated 1 on the beam 6 passes through the firing region 23 and passes through the furnace outlet 32 to the outside of the furnace. It is conveyed to. Subsequently, as shown in FIG. 4D, the beam 6 is lowered, and the object to be heat-treated 1 is transferred from the beam 6 onto the wire 2 in the course of the descent. Finally, as shown in FIG. 4 (e), the beam 6 moves backward while descending and returns to the initial state. By repeating these operations, the second transport mechanism can transport the object to be heat treated.

  In this example, the stroke of the movement of the beam 6 in the front-rear direction is set to be longer than the length of the firing region 23. By setting in this way, the beam 6 can be moved forward once. Since the object to be heat-treated 1 passes through the firing region 23 and is taken out of the furnace, it is easy to quickly pass the material to be heat-treated 1 through the firing region 23 in a short time. Cooling can be performed.

  In the first transport mechanism and the second transport mechanism, as shown in FIGS. 2 and 3, the object to be heat-treated 1 is held and transported on the wires 2 a, 2 b and the beam 6 in direct contact with them. However, in the case where the object to be heat-treated 1 is a solar cell substrate, a holding member for holding the object to be heat-treated 1 is attached to the wire, beam or chain. It is preferable to hold the heat treatment object in a state where the holding member is in contact with only the edge of the heat treatment object. The solar cell substrate is printed with the electrode paste pattern on the back surface as well as on the back surface, and if the transport mechanism is in contact with it, the printed surface will be scratched or burned, and the material to be heat treated In order to adversely affect the performance and appearance, it is desirable to use the holding member as described above and to limit the contact of the transport mechanism to the object to be heat-treated only to the edge of the object to be heat-treated without pattern printing.

  For example, FIG. 5 illustrates a state where a holding member is attached to the beam. In this example, the holding member 35 of the beam 6 is a member having a claw-like portion extending in a direction perpendicular to the axial direction of the beam 6, and a plurality of holding members 35 are provided on the beam 6 with a predetermined interval in the transport direction. A piece is installed. The holding member 35 has an inclined portion 36 that is inclined so as to become lower toward the center line L side of the conveyance path, and contacts only the edge of the object to be heat-treated 1 at the inclined portion 36. Hold object 1.

  As described above, the continuous heat treatment furnace of the present invention has a plurality of transport mechanisms, and is configured to transport the heat-treated material by separate transport mechanisms in the drying / debinding region and the firing region. Therefore, by setting the transport speeds of these transport mechanisms to be different, the transport speed of the heat-treated object in the drying / debinding region and the transport speed of the heat-treated object in the firing region can be made different. As described above, in order to obtain an ideal drying / firing curve in the heat treatment of the solar cell substrate, the conveyance speed of the heat treatment object in the baking area is higher than the conveyance speed of the heat treatment object in the drying / debinding area. In the present invention, it is required to quickly pass through the firing region maintained at a high temperature of 1000 ° C. or higher in a short time, but in the present invention, by separately setting the transport speed of each transport mechanism, An ideal drying / firing curve can be realized.

  The object to be heat-treated is, for example, a rectangular solar cell substrate having a side of about 15 cm, and the baking temperature is adjusted to about 2 m and the atmospheric temperature is adjusted to about 1000 ° C. In the case where the length of the region is about 0.3 m, the material to be heat-treated passes through the drying / debinding region in about 18 seconds, and then passes through the firing region in about 5 seconds and is conveyed outside the furnace. Is preferable.

  The wire or chain used in the embodiment is not particularly limited in its material and shape as long as it can provide heat resistance that can withstand the furnace temperature and the necessary tension. For example, Inconel, Examples thereof include a strand made of a metal such as titanium, a wire made of a thin rod having a diameter of 1 to 2 mm, or a chain made of a metal or ceramic that is also excellent in heat resistance. In addition, the material of the beam used in the embodiment is preferably a material excellent in heat resistance and thermal shock resistance because it is exposed to the atmosphere in both the high temperature firing region and the low temperature outside the furnace. What consists of a silicon-type ceramic material can be used conveniently.

  The material to be heat-treated in the continuous heat treatment furnace according to the present invention is not particularly limited, but it is particularly preferably used for heat treatment of a relatively small and flat product such as a solar cell substrate. Can do.

  The continuous heat treatment furnace of the present invention can be suitably used for heat treatment of solar cell substrates and the like.

It is an outline explanatory view showing an example of an embodiment of a continuous heat treatment furnace concerning the present invention. It is a schematic explanatory drawing which shows an example of embodiment of a 1st conveyance mechanism. It is a schematic explanatory drawing which shows an example of embodiment of a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows the state by which the holding member was mounted | worn with the beam.

Explanation of symbols

1: Heat treated object, 2: Wire rod, 2a: First wire rod, 2b: Second wire rod, 3a: First wire rod holder, 3b: Second wire rod holder, 4a: Winding spring, 4b: Winding spring, 5a: First Support body, 5b: Second support body, 6: Beam, 7: Lifter, 8: Lifting drive device, 9: Horizontal movement device, 10: Beam drive device, 11: Infrastein (IR) heater, 12: Near infrared lamp Heater, 13: partition, 21: drying / debinding area, 22: buffering area, 23: firing area, 31: inlet, 32: outlet, 35: holding member, 36: inclined part.

Claims (11)

From the entrance side to the exit side of the furnace, at least one drying / debinding region for drying and / or debinding the heat-treated material, and a firing region for firing the heat-treated material are provided in order, A continuous heat treatment furnace in which a material to be heat-treated is dried and / or debindered while being transported through the drying / debinding region, and then fired while being transported through the firing region,
As a transport mechanism for transporting the object to be heat-treated, it has at least two transport mechanisms arranged along the transport direction of the object to be heat-treated, and each of the drying / debinding area and the baking area is separately provided. The material to be heat treated is transported by the transport mechanism, and the transport mechanism of each transport mechanism is configured such that the transport speed in the drying / debinding region and the transport speed in the baking region are different. A continuous heat treatment furnace with a set transfer speed.   The continuous heat treatment furnace according to claim 1, wherein the transport speed of each transport mechanism is set so that the transport speed in the baking region is faster than the transport speed in the drying / debinding region. As a transport mechanism for transporting the heat-treated object, the heat-treated object placed on the wire, beam or chain is transported by operating a wire, beam or chain stretched in the furnace length direction. A first transport mechanism, and a second transport mechanism that transports the heat-treated object placed on the beam, wire, or chain by operating the beam, wire, or chain,
The said heat processing thing is conveyed by said 1st conveyance mechanism in the said drying / debinder area | region, The said heat processing object is conveyed by the said 2nd conveyance mechanism in the said baking area | region. Continuous heat treatment furnace.   The first transport mechanism has two types of wires, beams or chains arranged at predetermined intervals so as to operate differently with respect to the continuous heat treatment furnace, or one of the first transport mechanism with respect to the heat treatment furnace. The continuous heat treatment furnace according to claim 3, further comprising two kinds of wire rods, beams or chains arranged at a predetermined interval so that the other is moved relative to the heat treatment furnace.   Of the two types of wires, beams or chains, one wire, beam or chain periodically repeats the operations of ascending, advancing, descending and retreating with a certain movement stroke, and the other wire, beam or chain. The continuous heat treatment furnace according to claim 4, which periodically repeats forward and backward operations with a constant stroke.   4. The continuous type according to claim 3, wherein the second transport mechanism has a beam, a wire, or a chain that periodically repeats the operations of ascending, advancing, descending, and retreating with a constant movement stroke with respect to the continuous heat treatment furnace. Heat treatment furnace.   The continuous heat treatment furnace according to any one of claims 3 to 6, wherein a holding member for holding the object to be heat-treated is attached to the wire, beam or chain of the first transport mechanism.   The continuous heat treatment furnace according to any one of claims 3 to 7, wherein a holding member for holding the object to be heat-treated is attached to a beam, wire, or chain of the second transport mechanism.   A plurality of the holding members are attached to the wire rods, beams or chains respectively arranged on the left and right sides of the center line of the conveyance path at intervals in the conveyance direction, and the holding members are arranged on the conveyance path. The continuous portion according to claim 7 or 8, wherein the continuous portion has an inclined portion that is inclined so as to become lower toward the center line side, and supports the heat-treated object by contacting only the edge of the heat-treated object at the inclined portion. Type heat treatment furnace.   The continuous region according to any one of claims 1 to 9, wherein a buffer region is provided between the drying / debinding region and the calcining region to alleviate a thermal effect of one of these regions from the other. Type heat treatment furnace.   The continuous heat treatment furnace according to any one of claims 1 to 10, wherein the object to be heat treated is a solar cell substrate.

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