JP4523479B2 - Continuous heat treatment furnace and heat treatment method - Google Patents

Description

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

  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 firing region for performing the heat treatment, the 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. 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, the baking after drying and / or debinding treatment on the solar cell substrate, that is, 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 conveying speed of the heat-treated product and to quickly pass through the firing region in which the atmospheric temperature is maintained at a high temperature of about 1000 ° C. within a short time.

  However, in a conventional continuous heat treatment furnace, a series of drying and / or debinding treatments and firing is performed while conveying the object to be heat-treated at the same speed in the drying / debinding region and the firing region by one type of transport mechanism. Due to the heat treatment structure, it was extremely difficult to achieve the ideal firing state as described above.

  In addition, in order to make the product characteristics of the heat-treated product uniform, it is important to stably hold the firing area at a constant high temperature, but a transport mechanism having a large heat capacity such as a mesh belt conveyor was used. In such a case, the temperature change in the firing region accompanying the movement of the transport mechanism becomes large, and a stable firing region temperature cannot be obtained. Furthermore, as described above, a heat treatment furnace having a structure in which a series of heat treatments are always performed at a constant conveyance speed by one type of conveyance mechanism has a low degree of freedom in designing the furnace length and partially shortens the furnace length. Thus, it was difficult to produce a space-saving furnace. Furthermore, not only can the heat-treated material be transported in the firing area quickly in a short time, but also the necessary heating time can be ensured and the heat-treated material can be transported so that the overall heating time is substantially uniform. It is important to obtain good product properties.

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 possible to provide a continuous heat treatment furnace that can be made fast, can stably hold the firing region at a constant high temperature, and has a high degree of freedom in designing the furnace length, and its By using such a heat treatment furnace, the necessary heat time is ensured and the heat time of the entire heat treatment object is made almost uniform while the heat treatment object is transported quickly and quickly in the firing region. It is in providing the heat processing method which can be performed.

  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 Is a continuous heat treatment furnace in which the object 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. The first transport mechanism with a beam or wire that periodically repeats ascending, advancing, descending, and retreating movements with a stroke, and a beam that periodically repeats the ascending, advancing, descending, and retreating actions with a constant stroke. Or a second transport mechanism having a wire, and a third transport mechanism having a beam that periodically repeats ascending, advancing, descending, and retreating with a certain stroke. The drying / debinding region transports the heat-treated material by the first transport mechanism, and the firing region transports the heat-treated material by the second transport mechanism. There is provided a continuous heat treatment furnace for conveying the object to be heat-treated after being conveyed to a predetermined position outside the furnace by the third conveying mechanism.

  Further, according to the present invention, there is provided a heat treatment method using the continuous heat treatment furnace, wherein the second conveyance is performed after the workpiece is transferred from the first conveyance mechanism to the second conveyance mechanism. The conveyance of the heat-treated object by the second conveyance mechanism during the period from the mechanism to the delivery of the heat-treated object to the third conveyance mechanism exhibits acceleration, deceleration, reacceleration, and stop behavior. In addition, a heat treatment method is provided in which the difference in the heating time between the longest part and the shortest part in the firing region within the portion of the object to be heat treated falls within the range of 0 to 1 second. The

  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 region, the heat treatment object passes through the firing region quickly in a short time, Since the object to be heat-treated can be rapidly heated and cooled, an ideal 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.

  In addition, by using a beam or wire having a smaller heat capacity than the mesh belt conveyor as the transport mechanism, the temperature change in the firing region associated with the moving operation of the transport mechanism is reduced, and a stable firing region temperature is obtained. It is done. Furthermore, since a separate transport mechanism is used for each region as described above, the tact pitch (distance that the workpiece is moved by one cycle of the transport mechanism) and the transport speed can be freely set in each region. As a result, at the furnace design stage, the degree of freedom in designing the furnace length is increased, and it is easy to produce a space-saving furnace by partially shortening the furnace length. It becomes.

  Further, according to the heat treatment method of the present invention, the necessary heat time is ensured and the heat time of the whole heat treatment object is made substantially uniform while the heat treatment object is transported quickly and quickly in the firing region. Can be.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to the following embodiments, and is within the scope of the gist of the present invention. Based on this knowledge, it should be understood that design changes, improvements, etc. can be made as appropriate.

  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 41 for drying and / or debinding the heat-treated object 1 from the inlet 51 side to the outlet 52 side of the furnace, and the heat treatment. A firing region 42 for firing the product 1 is provided in order, and the heat-treated object 1 is dried and / or debindered while being transported through the drying / debinding region 41 and then fired while being transported through the firing region 42. As a transport mechanism for transporting the workpiece 1, the transport mechanism has three transport mechanisms, a first transport mechanism, a second transport mechanism, and a third transport mechanism. 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.

  The first transport mechanism includes a beam 2 that periodically repeats the operations of ascending, advancing, descending, and retreating with a constant stroke. In the drying / debinding region 41, the first heat-treating object 1 is transported. One transport mechanism is used. The second transport mechanism includes the beam 11 that periodically repeats the operations of ascending, advancing, descending, and retreating with a constant stroke. In the firing region 42, the second transporting mechanism transports the workpiece 1 to be processed. Perform by mechanism. The third transport mechanism includes a beam 21 that periodically repeats the operations of ascending, advancing, descending, and retreating with a certain stroke. Used to transport to a predetermined position outside. In the first transport mechanism and the second transport mechanism, instead of the beam 2 and the beam 11, respectively, a wire rod that is stretched with a predetermined tension in the furnace length direction and performs the same operation as the beam is used. In this embodiment, an example in which beams are used for the first transport mechanism and the second transport mechanism will be described.

  When the object to be heat-treated 1 is a rectangular solar cell substrate having a side of about 15 cm, for example, the length of the drying / debinding region 41 is about 2 m and the length of the firing region 42 is about 0.3 m. Is preferred. In the drying / debinding area 41, the atmospheric temperature is adjusted to about 300 to 500 ° C. by a heating means such as an Infrastein (IR) heater 61 provided in the furnace ceiling, and the firing area 42 includes the furnace ceiling and / or Alternatively, it is desirable that the ambient temperature is adjusted to about 1000 ° C. by a heating means such as an electric heater 62 including a near infrared lamp heater provided in the hearth. The drying / debinding area 41 may be configured as one area, or may be divided into a plurality of drying / debinding areas.

  As described above, the first transport mechanism used in the present invention includes a beam that periodically repeats the operations of ascending, advancing, descending, and retreating with a constant stroke. FIG. 2 is a schematic explanatory view schematically showing an example of the embodiment of the first transport mechanism. In this example, in addition to the beam 2 performing the above operation, the beam 2 is in a lowered state. A support body 3 is provided for supporting the object to be heat-treated 1 when it is in (including the retreat operation). For example, a T-shaped column as shown in FIG. 2 can be used as the support 3, and an upper horizontal bar 3 a is provided between the two beams 2 arranged in parallel to the furnace length direction. Plural pieces are arranged upright at predetermined intervals so as to be in a direction orthogonal to the furnace length direction.

  The beam 2 is fixed to a beam support 4 as shown in FIG. The beam support 4 is configured to periodically repeat the ascending, advancing, descending, and retreating operations with a fixed stroke by a driving mechanism (not shown), whereby the beam 2 performs the same periodic operation. Do.

  FIG. 3A to FIG. 3E are schematic explanatory views showing the operation of the first transport mechanism. First, as shown in FIG. 3A, the beam 2 is in a lowered state. At this time, the object to be heat-treated is placed on the support 3 in the vicinity of the entrance of the drying / debinding area. Next, as shown in FIG. 3B, the beam 2 rises by a predetermined stroke, and in the course of this rise, the object to be heat-treated 1 is transferred from the support 3 onto the beam 2. Next, as shown in FIG. 3C, the beam moves forward by a predetermined stroke while being lifted. Subsequently, as shown in FIG. 3D, the beam 2 is lowered by a predetermined stroke, and the object to be heat-treated is transferred from the beam 2 onto the support 3 in the process of the descent. Finally, as shown in FIG. 3E, the beam 2 moves backward while descending and returns to the initial position. By periodically repeating these operations, the first transport mechanism transports the object to be heat treated in the drying / debinding area.

  In this first transport mechanism, the object to be heat-treated 1 is held on the beam 2 in direct contact with the beam 2 as shown in FIGS. 2 and 3A to 3E. 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 beam 2 and the holding member is It is preferable to hold the object to be heat-treated in a state where only the edge of the object to be heat-treated or the vicinity of the edge is in contact. 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 of the product, the holding member as described above is used, and the contact of the transport mechanism with the object to be heat-treated is limited to the edge of the object to be heat-treated without pattern printing or the vicinity of the edge. It is desirable to do. Moreover, when using the support body 3 as shown in FIG. 2, it is preferable to attach the same holding member also to the support body 3 for the same reason. Also, when a wire is used instead of the beam 2 in the first transport mechanism, it is preferable that a holding member that plays the same role is attached to the wire.

  FIG. 4 illustrates a state in which holding members are respectively attached to the beam and the support in the first transport mechanism. In this example, the holding member 5 of the beam 2 is a member having a claw-like portion extending in a direction perpendicular to the axial direction of the beam 2, and a plurality of holding members 5 are arranged on the beam 2 at a predetermined pitch. . This holding member 5 is in a state where the vicinity of the tip thereof is slightly inclined downward, and contacts only the edge of the object to be heat treated 1 at the inclined part to hold the object to be heat treated 1. The holding member 6 of the support 3 is a member having a claw-like portion extending in a direction orthogonal to the horizontal bar 3a on the upper portion of the T-shaped support. The holding member 6 is also in a state where the vicinity of the tip thereof is slightly inclined downward, and contacts only the edge of the object to be heat treated 1 at the inclined part to hold the object to be heat treated 1.

  Similarly to the first transport mechanism, the second transport mechanism used in the present invention includes a beam that periodically repeats ascending, advancing, descending, and retreating operations with a constant stroke. FIG. 5 is a schematic explanatory view showing an example of an embodiment of the second transport mechanism. In this example, in addition to the beam 11 performing the above operation, the beam 11 is in a lowered state (retracting operation). A support 13 for supporting the object to be heat-treated 1 is provided. For example, an inverted L-shaped column as shown in FIG. 5 can be used as the support 13, and the upper part is slightly inclined between the two beams 11 arranged in parallel to the furnace length direction. A plurality of the support bars 13a are arranged upright so that the support bars 13a are parallel to the furnace length direction.

  As shown in FIG. 1, the beam 11 is fixed to a beam support 14. The beam support 14 is configured to periodically repeat the ascending, advancing, descending, and retreating operations with a fixed stroke by a driving mechanism (not shown), whereby the beam 11 also performs similar periodic operations. Do.

  Similar to the first transport mechanism, also in the second transport mechanism, when the workpiece 1 is a solar cell substrate, a holding member 15 for holding the workpiece 1 on the beam 11. It is preferable to hold | maintain the to-be-processed object 1 in the state which the said holding member 15 contacted only the edge of the to-be-processed object 1 or the edge vicinity part. In the example of FIG. 5, the holding member 15 for the beam 11 is a member having a claw-like portion extending in a direction perpendicular to the axial direction of the beam 11, and a plurality of holding members 15 are arranged on the beam 11 at a predetermined pitch. ing. The holding member 15 is in a state where the vicinity of the tip of the claw-shaped portion is slightly inclined downward, and contacts only the edge of the object to be heat-treated 1 at the inclined part to hold the object to be heat-treated 1. In the second transport mechanism, when a wire is used instead of the beam 11, it is preferable that a holding member that performs the same role is attached to the wire.

  FIG. 6 is an explanatory diagram illustrating an example of a mounting state of the holding member 15 with respect to the beam 11. The second transport mechanism illustrated in FIG. 5 is configured such that a concave groove 34 is provided in the heat insulating material 33 and the beam 11 passes through the groove 34 as will be described later. The holding member 15 is fixed to the beam 11 via the leg portion 15a having a predetermined height so that the holding member 15 does not interfere with the heat insulating material around the groove 34. In the second transport mechanism illustrated in FIG. 5, the holding member is not attached to the support body 13 like the support body 3 of the first transport mechanism in FIG. 4, but as described above, the support body 13. The upper support bar 13a is slightly inclined, and the object to be heat-treated 1 can be held by contacting only the edge of the object to be heat-treated 1 at the inclined part.

  Fig.7 (a)-FIG.7 (e) are schematic explanatory drawings which show the operation | movement at the time of delivering a to-be-heated material from a 1st conveyance mechanism to a 2nd conveyance mechanism. First, as shown in FIG. 7 (a), the beam 2 of the first transport mechanism is lowered by a predetermined stroke before the firing area 42, and in the course of this lowering, the support at the end of the drying / debinding area is performed. 3, the object to be heat-treated 1 is delivered. Next, as shown in FIG. 7B, the beam 2 is retracted by a predetermined stroke, and the beam 11 of the second transport mechanism is also retracted by a predetermined stroke. It reaches a position below the support 3. Next, as shown in FIG. 7C, the beam 11 rises by a predetermined stroke, and in the course of this rise, the object to be heat treated 1 is transferred onto the beam 11 from the last support 3. . Subsequently, as shown in FIG. 7 (d), the beam 11 moves forward by a predetermined stroke while being lifted, and by this forward movement, the object to be heat-treated 1 on the beam 11 is provided in the firing region 42. It is conveyed onto the support 13. Thereafter, as shown in FIG. 7E, the beam 11 is lowered by a predetermined stroke, and the object to be heat-treated 1 is transferred from the beam 11 onto the support body 13 in the course of the descent. By periodically repeating such an operation, the workpieces are sequentially delivered from the first transport mechanism to the second transport mechanism. Further, by periodically repeating such an operation, the object to be heat-treated 1 transferred to the second transfer mechanism is further transferred toward the outlet direction, passes through the firing region 42, and a third to be described later. Delivered to the transport mechanism.

  As described above, the second transport mechanism is used for transporting the object to be heat-treated in the firing region. In the present invention, at least a part of the periphery of the beam of the second transport mechanism is used in the firing region. Is preferably surrounded by a heat insulating material. Specifically, for example, as shown in FIG. 5, a concave groove 34 is provided in the heat insulating material 33 so that the beam 11 passes through the groove 34. In the case where the atmosphere temperature in the firing region is set to a high temperature of about 1000 ° C., even when a beam 11 made of a highly heat-resistant metal material is used, the deterioration is severe and the life is short. The life of the beam 11 can be extended by enclosing it with Even when a wire rod is used instead of the beam 11 in the second transport mechanism, it is preferable that at least a part of the periphery of the wire rod is similarly surrounded by a heat insulating material.

  Further, when a solar cell substrate or the like is heat-treated in this type of continuous heat treatment furnace, air may be introduced from the outside into the region for adjusting the atmosphere in the drying / debinding region. In the present invention, as shown in FIG. 5, the beam 11 of the second transport mechanism is constituted by a hollow body (tubular body) having openings at both ends, and one opening located on the outlet side of the furnace is air. The supply opening 11a and the other opening located on the inlet side of the furnace are preferably used as the air discharge opening 11b so that air for adjusting the atmosphere flows through the inside of the beam 11 and is sent into the furnace. When the beam 11 is used as an air introduction tube for adjusting the atmosphere in this way, the beam 11 is cooled by the air, and the life of the beam 11 is improved. Further, the air for adjusting the atmosphere is appropriately heated in the process of passing through the beam 11, so that it is not necessary to preheat before introduction.

Further, in the present invention, at least in the firing region, and divided the furnace vertically structure, by driving the upper furnace and / or below the furnace in the vertical direction, the inlet and outlet sides of the baking area opening It is preferable that the height of the part can be changed. FIG. 8 is a schematic cross-sectional view of a firing region in which the furnace is divided into upper and lower parts in this way. In this example, the upper furnace 43 among the vertically divided furnaces 43, 44 can be driven in the vertical direction, thereby increasing the height of the opening 45 on the inlet side and the opening 46 on the outlet side of the firing region 42. Can be changed.

  Since the heat in the firing region 42 easily escapes from the opening 45 on the entrance side and the opening 46 on the exit side of the firing region 42, the height of these openings 45, 46 is the top and bottom of the beam 11 in the second transport mechanism. It is desirable to make it as low (narrow) as possible within a range not hindering the operation in the direction from the viewpoint of suppressing energy consumption required for maintaining the temperature in the firing region and stabilizing the temperature in the firing region. If the heights of the openings 45 and 46 on the inlet side and outlet side of the firing region 42 can be changed as described above, it becomes easy to adjust the height to an ideal height.

  The third transport mechanism used in the present invention includes a beam that periodically repeats the operations of ascending, advancing, descending, and retreating with a constant stroke. FIG. 9 is a schematic explanatory view schematically showing an example of an embodiment of the third transport mechanism. In this example, the third transport mechanism is a lifting drive device 23 that lifts and lowers the lifter 22. A beam driving device 25 that moves the beam 21 attached to the lifter 22 in the front-rear direction, and a horizontal movement device 24 that horizontally moves the elevating drive device itself in the front-rear direction. The operations of ascending, advancing, descending, and retreating can be periodically repeated with a certain stroke.

  FIG. 10A to FIG. 10E are schematic explanatory views showing an operation in which the third transport mechanism receives the heat-treated material from the second transport mechanism and transports it to a predetermined position outside the furnace. It is. First, as shown in FIG. 10 (a), the beam 21 is in a lowered state, and as shown in FIG. 10 (b), the workpiece 1 is moved to the vicinity of the exit of the firing region by the second transport mechanism. It starts to rise when it is transported. In the ascending process, the object to be heat-treated 1 is transferred from the beam 11 to the beam 21 of the second transport mechanism. Next, as shown in FIG. 10 (c), the beam 21 moves forward by a predetermined stroke while being lifted, and the workpiece 1 on the beam 21 is transported to a predetermined position outside the furnace by this forward movement. Subsequently, as shown in FIG. 10D, the beam 21 is lowered by a predetermined stroke, and in the course of this lowering, the object to be heat-treated 1 is subjected to the subsequent process provided at the predetermined position from the beam 21. Therefore, it is transferred to another transfer line 71 and the like. Thereafter, as shown in FIG. 10E, the beam 21 moves backward while descending and returns to the initial position. By periodically repeating these operations, the third transport mechanism can receive the object to be heat-treated from the second transport mechanism and transport it to a predetermined position outside the furnace.

  As shown in FIG. 5, the beam 21 of the third transport mechanism is parallel to the beam 11 at, for example, a position between the two beams 11 so as not to interfere with the beam 11 of the second transport mechanism. To be placed in. Moreover, in the example of this figure, although the beam 21 of the 3rd conveyance mechanism is comprised with one beam, you may comprise with a several beam. As shown in FIG. 5, when the beam 21 of the third transport mechanism is composed of one beam, the tip of the beam 21 that receives the heat-treated material 1 from the beam 11 is more than the object to be heat-treated 1. It is preferable to attach a receiving plate 26 made of a flat plate having a somewhat small size so that stable receiving can be performed.

  The continuous heat treatment furnace of the present invention has the three conveyance mechanisms as described above, and is configured to convey the heat-treated material by separate conveyance mechanisms, particularly in the drying / debinding area and the baking area. Therefore, by setting the transport speeds of these transport mechanisms to be different, the transport speed of the object to be heat treated in the drying / debinding area and the transport speed of the object to be heat treated in the firing area 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 about 1000 ° C. within a short time. In the present invention, by separately setting the transport speed of each transport mechanism, It is possible to realize an ideal firing curve.

  Moreover, in order to make the product characteristics (quality) of the material to be heat treated uniform, it is an important issue to stably hold the firing region at a constant high temperature. This can be achieved by using the second transport mechanism as described above for transport of the object to be heat treated. That is, since the second transport mechanism uses a beam or wire having a small heat capacity compared to a transport mechanism such as a mesh belt conveyor, the temperature change in the firing region due to the moving operation of the transport mechanism is reduced. Can be suppressed.

  Furthermore, since a separate transport mechanism is used for each region as described above, the tact pitch (distance that the workpiece is moved by one cycle of the transport mechanism) and the transport speed can be freely set in each region. As a result, at the furnace design stage, the degree of freedom in designing the furnace length is increased, and it is easy to produce a space-saving furnace by partially shortening the furnace length. There is also an advantage that it becomes.

  An object to be heat-treated in the continuous heat treatment furnace of the present invention is, for example, a rectangular solar cell substrate having a side of about 15 cm, and the length of the drying / debinding region with the atmospheric temperature adjusted to 300 to 500 ° C. is about In the case where the length of the firing area adjusted to 2 m and the atmospheric temperature is adjusted to about 1000 ° C. is about 0.3 m, the material to be heat-treated passes through the drying / debinding area in about 70 to 90 seconds, and then for about 5 seconds. It is preferable to pass through the firing region and to be conveyed to the outside of the furnace.

  In the present invention, the tact pitch of the second transport mechanism is set such that the heat treatment object is transferred from the first transport mechanism to the second transport mechanism, and the tapped pitch from the second transport mechanism to the third transport mechanism. It is preferable to set to 1/2 of the distance from the delivery position of the heat-treated product. When the tact pitch of the second transport mechanism is set to such a distance, after the second transport mechanism receives the heat-treated material from the first transport mechanism, the second transport mechanism performs heat treatment in one cycle of operation. The product is transported to the center of the firing region, temporarily stops, and the heat-treated material passes through the firing region and is transported to the delivery position to the third transport mechanism by another cycle of operation. That is, since the transfer of the material to be heat-treated in the firing region can be completed quickly by the operation of only two cycles of the second transfer mechanism, high production efficiency is obtained, and the position where the material to be heat-treated is temporarily stopped is Since the heat-treated product is the central part of the firing region that is most easily heated, unevenness in the heat-treated state is unlikely to occur, and a high-quality product can be obtained.

  On the other hand, for example, when the tact pitch of the second transport mechanism is set to be shorter and the heat treatment object is transported through the firing region and stopped many times in the firing region, it is quick. In addition to difficult conveyance, any of the stop positions of the object to be heat treated tends to have a large temperature distribution in the vicinity of the inlet side opening and the outlet side opening of the firing region, which causes unevenness in the heat treatment state. Cheap. In addition, for example, it is possible to set the tact pitch of the second transport mechanism long so that the transport of the firing region of the object to be heat-treated can be completed by one cycle operation of the second transport mechanism. In this case, the time required for the forward or backward operation of the beam or wire becomes longer, and as a result, the time required for one cycle of operation becomes longer, so that a very high production efficiency cannot be obtained.

  In the continuous heat treatment furnace of the present invention, the conveyance path through which the object to be heat-treated is conveyed may be provided in only one row in the furnace, but in order to improve productivity, It is preferable that a plurality of rows of conveyance paths for the heat-treated material provided with the one conveyance mechanism, the second conveyance mechanism, and the third conveyance mechanism are provided in parallel in the furnace. In this case, it is preferable that partition walls are provided between the respective transport paths at least in the firing region, and the inside of the furnace is partitioned for each transport path by the partition walls.

  In a conventional solar cell substrate continuous heat treatment furnace equipped with a mesh belt conveyor as the transport mechanism, even when multiple rows of transport paths for the object to be heat-treated are provided, the entire row can be transported with a wide single mesh belt. As shown in FIGS. 12 (a) and 12 (b), which are schematic explanatory views of the inside of the firing region as viewed from above and from the side, respectively, the inlet side opening 45 and the outlet of the firing region 42 It is necessary to widen the opening width W of the side opening 46 so that the mesh belt can pass through, and a structure in which a partition is provided between the conveyance paths and the inside of the furnace is partitioned for each conveyance path. It is difficult. Thus, when the opening width W of the inlet side opening 45 and the outlet side opening 46 is wide, the heat in the firing region 42 easily escapes from the opening, and the heat loss increases. In addition, since the inside of the furnace is a single wide space, it is difficult to individually control the temperature for each transport path, and it is difficult to ensure the uniformity of the temperature distribution.

  On the other hand, the continuous heat treatment furnace of the present invention is easy to install partition walls between the respective transport paths due to the structure of the transport mechanism, and the schematic explanation of the inside of the firing region viewed from above and from the side surface direction, respectively. As shown in FIGS. 11 (a) and 11 (b), the inside of the furnace can be divided for each conveyance path by a partition wall 81 provided between the respective conveyance paths, and an inlet side opening is provided for each conveyance path. The opening width W can be narrowed by providing the part 45 and the outlet side opening 46. Thus, if the opening width W of the entrance side opening part 45 and the exit side opening part 46 is narrow, it will become difficult for the heat | fever in the baking area | region 42 to escape from the said opening part, and heat loss can be reduced. Further, since the inside of the furnace is divided for each conveyance path, it is easy to individually control the temperature for each conveyance path, and it is easy to ensure the uniformity of the temperature distribution.

  FIG. 13 is a schematic explanatory view of the firing region of the continuous heat treatment furnace according to the present invention in which a plurality of conveyance paths are provided as viewed from the conveyance direction side. As shown in the figure, the partition wall 81 is composed of an upper partition wall 81a extending downward from the furnace ceiling portion and a lower partition wall 81b extending upward from the hearth portion, and is recessed so that the beam 11 passes through the upper end surface of the lower partition wall 81b. It is preferable to form a groove and provide a gap between the upper partition 81 a and the lower partition 81 b so as not to interfere with the support 15 attached to the beam 11. Note that the lower partition 81b may be made of the heat insulating material 33 as shown in FIG. Thus, when the partition 81 is provided between the transport paths, as described above, it becomes easier to individually control the temperature for each transport path, as compared with the case where the partition is not provided. It becomes possible to heat the object to be heat-treated more quickly and uniformly.

  That is, when the partition 81 is provided as described above, a part of the heat radiated from the heating means such as the near-infrared lamp heater provided in the firing region such as the near-infrared lamp heater is absorbed by the partition 81. However, when the temperature of the partition 81 rises as a result, heat is also radiated from the partition 81, and the entire wall surface around the workpiece 1 becomes a heater, so that the workpiece 1 is concentrated uniformly. Since heating is performed, the heating rate of the object to be heat-treated 1 is improved as compared with the case where no partition is provided, and a more uniform heat treatment state is obtained. Further, even in a heat treatment furnace in which a heater had to be installed not only above but also below the object to be heat treated, the partition wall is installed as described above, and the entire wall surface around the object to be heat treated is provided. By using a heater, it may be possible to eliminate the need for a lower heater.

  In the case of providing the partition walls in this way, in order to facilitate temperature control for each transport path, heating means capable of independently controlling the temperature are separately provided in each transport path partitioned by the partition walls. It is preferable to make it. In this case, as shown in FIGS. 11 (a) and 11 (b), an electric heater 62 ′ such as a U-shaped near infrared lamp heater is arranged in parallel with the conveying direction as a heating means. It is preferable to do.

  As shown in FIG. 12 (a) and FIG. 12 (b), in a continuous heat treatment furnace having a conventional structure in which a mesh belt conveyor is used as a transport mechanism and no partition is provided between a plurality of transport paths, It is common to install a straight tubular long near-infrared lamp heater 62 ″ so as to be bridged in the furnace width direction. However, the near-infrared lamp heater used for the heat treatment of the solar cell substrate has one structure per one. There is an upper limit to the power applied to the light source, and there is a problem that the power density per unit area is reduced when such a straight tubular long near infrared lamp heater 62 ″ is used.

  On the other hand, when the electric heater 62 'including the U-shaped relatively short near-infrared lamp heater as described above is arranged in parallel to the transport direction for each transport path, it is individually provided for each transport path. Not only temperature control but also power density per unit area can be kept high, even if the power consumption of the whole furnace is the same compared to the case of using a long straight infrared lamp heater with a straight tube as in the past. The temperature of the object to be heat-treated can be increased more quickly.

  The material of the beam used in the transport mechanism of the present invention is preferably a material excellent in heat resistance and thermal shock resistance. For example, a material made of a silicon carbide ceramic material can be suitably used. Further, the material of the wire used in the transport mechanism of the present invention is not particularly limited as long as it has heat resistance that can withstand the furnace temperature and can give necessary tension. However, for example, a stranded wire of a metal such as Inconel or titanium, a wire made of a thin rod having a diameter of about 1 to 2 mm, or a chain made of a metal or ceramic that is also excellent in heat resistance can be cited.

  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 heat treatment method according to the present invention is a method for performing heat treatment of an object to be heat treated using the heat treatment furnace according to the present invention, wherein the object to be heat treated is transferred from the first transport mechanism to the second transport mechanism. The transfer of the object to be heat-treated by the second transfer mechanism during the period from the second transfer mechanism to the delivery of the object to be transferred to the third transfer mechanism shows the behavior of acceleration, deceleration, reacceleration, and stop. At the same time, the difference in the heating time between the longest part and the shortest part in the firing region within the part to be heat-treated is set within the range of 0 to 1 second.

  As described above, the heat treatment furnace according to the present invention is configured such that the heat treatment object is conveyed by the separate and independent conveyance mechanism in the drying / debinding region and the baking region, so that the heat treatment object in the baking region is obtained. Although the transfer can be performed quickly in a short time, in order to obtain good product characteristics, not only the transfer is performed quickly, but also the necessary heating time is ensured and the material to be heat-treated in the firing area It is important to ensure that the overall heating time is approximately uniform.

  Therefore, in this method, after the material to be heat treated is transferred (transferred) from the first transport mechanism to the second transport mechanism, the material to be heat treated is transferred (transferred) from the second transport mechanism to the third transport mechanism. In addition to the behavior of acceleration, deceleration, re-acceleration, and stop of the transfer of the heat-treated object by the second transfer mechanism until the loading), the heating time in the firing region within the part of the heat-treated object The difference in the heating time between the longest part and the shortest part was kept within the range of 0 to 1 second.

  The position where the acceleration, deceleration, reacceleration, and stop operations are started can be arbitrarily selected as long as the difference in the heating time can be kept within a range of 0 to 1 second. 14, the position where the workpiece 1 is transferred from the first transport mechanism to the second transport mechanism is the acceleration position A, and the rear end of the workpiece 1 is on the entrance side of the firing region 42. The position reaching the inner opening end of the opening 45 is the deceleration position B, the position where the front end of the workpiece 1 reaches the inner opening end of the outlet opening 46 in the firing region 42 is the reacceleration position C, and the second transfer. There is an arrangement in which the stop position D is a position where the workpiece 1 is transferred from the mechanism to the third transport mechanism.

  Even when the start position of each operation is set to other positions, the position of the workpiece 1 at the start of deceleration (deceleration position B) and the position of the workpiece 1 at the start of reacceleration (reacceleration) The position C) is symmetrical with respect to the straight line I that bisects the firing region 42 in the transport direction, so that the heating time in the firing region 42 of each part of the object to be heat treated 1 is made uniform. This is preferable.

  The difference in heating time between the longest heating time and the shortest heating time in the firing region among the respective portions of the workpiece 1 depends on the start position of each operation, particularly the deceleration position B and the reacceleration position C. It is possible to control, and by appropriately adjusting these positions, the difference in the heating time can fall within the range of 0 to 1 second. In the present invention, the “heating time in the firing region” means that each part of the object to be heat-treated 1 stays in the firing region 42 (except in the entrance-side opening 45 and the exit-side opening 46). Means time. If the difference in heating time exceeds 1 second, unevenness occurs in the heated state of the object to be heat-treated 1 and it becomes difficult to obtain good product characteristics.

  Between the acceleration position A and the deceleration position B, and between the reacceleration position C and the stop position D, the transfer is performed at a relatively high speed from the viewpoint of shortening the entire transfer time of the object to be heat-treated 1 in the firing region 42, Between the deceleration position B and the reacceleration position C, conveyance is performed at a relatively low speed so as to ensure a necessary heating time. In this way, acceleration and deceleration are performed to change the conveying speed of the object to be heat-treated 1 in the firing region 42, and the heat-treated object 1 is adjusted as described above by adjusting the deceleration position B, the reacceleration position C, and the like. By setting the difference in the heating time of each part within a predetermined range, the necessary heat treatment time is ensured while carrying the material to be heat-treated 1 in the firing region 42 quickly in a short time. It becomes possible to make the whole heating time substantially uniform.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

(Reference example)
In the heat treatment furnace according to the present invention, as shown in FIG. 15, the length of the firing region 42 is L ₁ , the length in the transport direction of the workpiece 1 is Y, and the inlet side opening 45 and the outlet side opening 46 are It is assumed that the thickness of the formed furnace wall is L _2, and Y and L ₂ are equal. After the delivery of the object to be heat-treated 1 from the first conveyance mechanism to the second conveyance mechanism, by the second conveyance mechanism from the second conveyance mechanism to the delivery of the object to be treated 1 to the third conveyance mechanism. The position at which the workpiece 1 is transferred from the first transfer mechanism to the second transfer mechanism is set to the acceleration position A so that the transfer of the workpiece 1 is accelerated, decelerated, reaccelerated, and stopped. The position where the front end of the object to be heat-treated 1 reaches the inner opening end of the inlet side opening 45 is the deceleration position B, and the position where the front end of the object to be heat treated 1 reaches the inner opening end of the outlet side opening 46 is re-accelerated. C, the position where the workpiece 1 is transferred from the second transport mechanism to the third transport mechanism is the stop position D, the transport speed from the acceleration position A to the deceleration position B is v ₁ , and from the deceleration position B the conveying speed of up reacceleration position C and v _2, the re-acceleration position C Conveying speed to stop position D are equal to v _1. Here, when the independent variable y is introduced with the rear end of the workpiece 1 being 0 (minimum value) and the length Y in the transport direction of the workpiece 1 being the maximum value, the rear end of the workpiece 1 is The heating time T (y) in the firing region 42 at the site where the distance is y is obtained by the following equation (1).
_{T (y) = L 1 /} v 2 - (Y-y) / v 2 + (Y-y) / v 1 ...... (1)

The heating time for each part of the object to be heat-treated 1 was calculated from the above formula (1) under the following conditions, and the result was graphed and shown in FIG.
L ₁ = 0.4 (m)
L ₂ = 0.15 (m)
Y = 0.15 (m)
v ₁ = 15 (m / min)
v ₂ = 4 (m / min)

  As shown in FIG. 19, in this example, the front end of the object to be heat-treated 1 (the part whose distance from the rear end of the object to be heat-treated 1 is 150 mm) is the part with the longest heating time, and the rear end of the object to be heat-treated 1 The part where the distance from the rear end of the object 1 was 0 mm) was the part with the shortest heating time, and the difference between the two heating times was 1.65 seconds (= 6 seconds−4.35 seconds).

  In addition, the heat treatment was actually performed under the above conditions, and the temperature was measured with a thermocouple using the front end, the center of the heat-treated object (the distance from the rear end of the heat-treated object 1 as 75 mm), and the rear end as the measurement points. The results are shown in a graph in FIG. As shown in this figure, in this example, there was a large difference in the maximum temperature between the front end, the center, and the rear end of the object to be heat-treated, and the maximum temperature was lower as the heating time was shorter.

Example 1
As shown in FIG. 16, the position where the center of the workpiece 1 reaches the inner opening end of the inlet opening 45 is the deceleration position B, and the center of the workpiece 1 is the inner opening end of the outlet opening 46. The heating time T (y) in the firing region 42 of the part where the distance from the rear end of the object to be heat-treated 1 is y is the same as that in the reference example except that the reaching position is the reacceleration position C. It calculated | required by (2) (when y <0.075 (m)) and the following Formula (3) (when y> 0.075 (m)), and the result was graphed and shown in FIG.
_{T (y) = L 1 /} v 2 + (y-Y / 2) (1 / v 2 -1 / v 1) ...... (2)
_{T (y) = L 1 /} v 2 - (y-Y / 2) (1 / v 2 -1 / v 1) ...... (3)

  As shown in FIG. 20, in this example, the center of the object to be heat treated 1 is the part with the longest heating time, and the front end and the rear end of the object to be heat treated 1 are the parts with the shortest heating time. .825 seconds (= 6 seconds−5.175 seconds).

  Further, the heat treatment was actually carried out under the above conditions, the temperature was measured with a thermocouple using the front end, the center, and the rear end of the object to be heat treated as measurement points, and the result was graphed and shown in FIG. As shown in this figure, in this example, although there were some differences in the maximum temperature at the front end, center, and rear end of the object to be heat treated, the difference was small compared to the result of the reference example (FIG. 23). there were.

(Example 2)
As shown in FIG. 17, the position where the rear end of the object to be heat treated 1 reaches the inner opening end of the inlet side opening 45 is the deceleration position B, and the front end of the object to be heat treated 1 is the inner opening end of the outlet side opening 46. The heating time T (y) in the firing region 42 of the part where the distance from the rear end of the object to be heat-treated 1 is y is set to be the same as in the above-described reference example except that the position reaching the re-acceleration position C is set to the re-acceleration position C. It calculated | required by Formula (4) and the result was graphed and shown in FIG.
T (y) = (L ₁ −Y) / v ₂ + Y / v ₁ (4)

  As shown in FIG. 21, in this example, the heating time for each part of the object 1 to be heat-treated was all the same (4.53 seconds), and the difference in the heating time for each part was zero.

  Further, the heat treatment was actually carried out under the above conditions, the temperature was measured with a thermocouple using the front end, the center, and the rear end of the object to be heat treated as measurement points, and the result was graphed and shown in FIG. As shown in this figure, in this example, there was almost no difference in the maximum temperature between the front end, the center, and the rear end of the object to be heat treated.

(Example 3)
As shown in FIG. 18, the position where the front end of the object to be heat-treated 1 reaches the inner opening end of the inlet side opening 45 is the deceleration position B, and the rear end of the object to be heat treated 1 is the inner opening end of the outlet side opening 46. The heating time T (y) in the firing region 42 of the part where the distance from the rear end of the object to be heat-treated 1 is y is set to be the same as in the above-described reference example except that the position reaching the re-acceleration position C is set to the re-acceleration position C. It calculated | required by Formula (5) and the result was graphed and it showed in FIG.
T (y) = L ₁ / v ₂ (5)

  As shown in FIG. 22, in this example, the heating time for each part of the object to be heat treated 1 was the same (6 seconds), and the difference in the heating time for each part was 0.

  Further, the heat treatment was actually performed under the above conditions, and the temperature was measured with a thermocouple using the front end, the center, and the rear end of the object to be heat treated as measurement points, and the result was graphed and shown in FIG. As shown in this figure, in this example, there was almost no difference in the maximum temperature between the front end, the center, and the rear end of the object to be heat treated.

  As described above, from the results of the reference examples and Examples 1 to 3, it is found that when the deceleration position and the reacceleration position are arranged as in Example 2 and Example 3, the heating time of the entire heat-treated object becomes uniform, which is most preferable. . In the actual heat treatment, the arrangement of the second embodiment and the third embodiment may be determined based on the required heating time, the target transport cycle time, and the like. In Example 1, although the difference in the heating time of each part of the object to be heat-treated does not become 0 as in Example 2 and Example 3, the difference is about ½ of the reference example. Therefore, in the case where the arrangement as in Example 2 or Example 3 is difficult, there may be a case where sufficient soaking is possible even by adopting the arrangement as in Example 1. In common with Examples 1 to 3, as shown in FIGS. 16 to 18, the deceleration position B and the reacceleration position C are symmetrical with respect to a straight line I that bisects the firing region in the transport direction. It is that you are. With such an arrangement, even if a distribution occurs in the heating time of each part of the object to be heat treated, it becomes a symmetric distribution with the maximum heating time at the center in the length direction of the object to be heat treated. As in the example, there is no significant difference in heating time between the front end and the rear end.

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

It is a schematic explanatory drawing which shows an example of embodiment of the continuous heat processing furnace which concerns on this 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 operation | movement of a 1st conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 1st conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 1st conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 1st conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 1st conveyance mechanism. In a 1st conveyance mechanism, it is explanatory drawing which shows the state by which the holding member was each mounted | worn with the beam and the support body. It is a schematic explanatory drawing which shows an example of embodiment of a 2nd conveyance mechanism. It is explanatory drawing which shows the example of the mounting state of the holding member with respect to a beam in a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows the operation | movement at the time of delivering a to-be-heated material from a 1st conveyance mechanism to a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows the operation | movement at the time of delivering a to-be-heated material from a 1st conveyance mechanism to a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows the operation | movement at the time of delivering a to-be-heated material from a 1st conveyance mechanism to a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows the operation | movement at the time of delivering a to-be-heated material from a 1st conveyance mechanism to a 2nd conveyance mechanism. It is a schematic explanatory drawing which shows the operation | movement at the time of delivering a to-be-heated material from a 1st conveyance mechanism to a 2nd conveyance mechanism. It is explanatory drawing which shows the state which made the furnace the upper and lower division structure. It is a schematic explanatory drawing which shows an example of embodiment of a 3rd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 3rd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 3rd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 3rd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 3rd conveyance mechanism. It is a schematic explanatory drawing which shows operation | movement of a 3rd conveyance mechanism. It is the schematic explanatory drawing which looked at the inside of the baking area | region of the continuous-type heat treatment furnace which concerns on this invention provided with multiple rows of conveyance paths from the upper direction. It is the schematic explanatory drawing which looked at the inside of the baking area | region of the continuous-type heat treatment furnace which concerns on this invention provided with multiple rows of conveyance paths from the side surface direction. It is the schematic explanatory drawing which looked at the inside of the baking area | region of the conventional continuous heat processing furnace provided with multiple rows of conveyance paths from the upper direction. It is the schematic explanatory drawing which looked at the inside of the baking area | region of the conventional continuous heat processing furnace provided with multiple rows of conveyance paths from the side surface direction. It is the schematic explanatory drawing which looked at the baking area | region of the continuous heat processing furnace which concerns on this invention provided with multiple rows of conveyance paths from the conveyance direction side. It is outline | summary explanatory drawing which shows the position where each operation | movement of acceleration, deceleration, reacceleration, and a stop is started. It is an outline explanatory view showing conditions etc. in a reference example. FIG. 3 is a schematic explanatory diagram illustrating conditions and the like in the first embodiment. FIG. 10 is a schematic explanatory diagram illustrating conditions and the like in the second embodiment. 10 is a schematic explanatory diagram showing conditions and the like in Example 3. FIG. It is a graph which shows the result of a reference example. 3 is a graph showing the results of Example 1. 10 is a graph showing the results of Example 2. 10 is a graph showing the results of Example 3. It is a graph which shows the result of a reference example. 3 is a graph showing the results of Example 1. 10 is a graph showing the results of Example 2. 10 is a graph showing the results of Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Material to be heat-treated, 2 ... Beam, 3 ... Support, 4 ... Beam support, 5 ... Holding member, 6 ... Holding member, 11 ... Beam, 11a ... Air supply port, 11b ... Air discharge port, 13 ... Support Body, 15 ... Holding member, 15a ... Leg, 21 ... Beam, 22 ... Lifter, 23 ... Lifting drive device, 24 ... Horizontal movement device, 25 ... Beam drive device, 26 ... Receiving plate, 33 ... Insulating material, 34 ... Groove, 41 ... drying / debinding region, 42 ... firing region, 43 ... furnace (upper side), 44 ... furnace (lower side), 45 ... inlet side opening, 46 ... outlet side opening, 51 ... inlet, 52 ... Outlet, 61 ... Infrastein (IR) heater, 62 ... Electric heater, 71 ... Other transfer line, 81 ... Partition, 81a ... Upper partition, 81b ... Lower partition

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 the transport mechanism for transporting the object to be heat-treated, the first transport mechanism equipped with a beam or wire that periodically repeats ascending, advancing, descending, and retreating with a constant stroke, and also rising with a constant stroke , A second transport mechanism that includes a beam or wire that periodically repeats the operations of forward, downward, and backward movement, and a third that includes a beam that periodically repeats the upward, forward, downward, and backward movements at a constant stroke. And a transport mechanism
In the drying / debinding area, the heat-treated object is conveyed by the first conveying mechanism, and in the baking area, the heat-treated object is conveyed by the second conveying mechanism, and the baking area is conveyed. The latter to-be-heated material is transported to a predetermined position outside the furnace by the third transport mechanism,
A continuous heat treatment furnace in which at least a part of the periphery of the beam or wire of the second transport mechanism is surrounded by a heat insulating material that is not integrated with the beam or wire in the firing region.   The continuous heat treatment furnace according to claim 1, wherein a holding member for holding the object to be heat-treated is attached to the beam or wire of the first transport mechanism.   The continuous heat treatment furnace according to claim 1 or 2, wherein a holding member for holding the object to be heat-treated is attached to the beam or wire of the second transport mechanism.   The beam of the second transport mechanism is a hollow body having openings at both ends, one opening is used as an air supply port, and the other opening is used as an air discharge port. The continuous heat treatment furnace according to any one of claims 1 to 3, wherein a continuous heat treatment furnace is circulated and fed into the furnace.   At least in the firing region, the furnace has a structure that is vertically divided, and by driving the upper furnace and / or the lower furnace in the up-and-down direction, the openings on the inlet side and the outlet side of the firing region are provided. The continuous heat treatment furnace according to any one of claims 1 to 4, wherein the height can be changed.   A plurality of rows of the heat treatment object conveyance paths provided with the first conveyance mechanism, the second conveyance mechanism, and the third conveyance mechanism are provided in parallel in the furnace, and at least in the firing region, The continuous heat treatment furnace according to any one of claims 1 to 5, wherein a partition wall is installed between the transport paths, and the transport paths are partitioned by the partition walls.   The continuous heat treatment furnace according to claim 6, wherein heating means capable of independently controlling the temperature are separately provided in each of the conveyance paths partitioned by the partition walls.   The continuous heat treatment furnace according to claim 7, wherein the heating means is a U-shaped electric heater disposed in parallel with a conveyance direction of the object to be heat treated.   The continuous heat treatment furnace according to any one of claims 1 to 8, wherein the object to be heat treated is a solar cell substrate.   A heat treatment method using the continuous heat treatment furnace according to any one of claims 1 to 9, wherein after the delivery of the heat-treated material from the first transport mechanism to the second transport mechanism, Transport of the heat-treated object by the second transport mechanism between the second transport mechanism and the delivery of the heat-treated material to the third transport mechanism is accelerated, decelerated, reaccelerated, and stopped. And a difference in heating time between the longest part and the shortest part in the firing region of the part to be heat treated within the range of 0 to 1 second. .   The position of the object to be heat-treated at the start of the deceleration and the position of the object to be heat-treated at the start of the reacceleration are symmetrical with respect to a straight line that bisects the firing region in the transport direction. The heat treatment method according to claim 10.

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