JP5216246B2 - Continuous firing furnace - Google Patents

Description

  The present invention relates to a continuous firing furnace used in a manufacturing process of a plasma display panel (PDP) or the like and used in a glass substrate firing process, a glass substrate annealing process, or the like.

  The continuous firing furnace includes a plurality of heat treatment zones having different set temperatures in the furnace. Each heat treatment zone is continuously formed along a conveyance path along which a processing object such as a glass substrate is conveyed. The conveyance path is configured by roller hearth or the like. Each processing object is continuously or tact-transferred on the transfer path at a predetermined interval. Each processing object is subjected to a predetermined heat treatment in each heat treatment zone.

  In the continuous firing furnace, a certain amount of heat is taken out of the continuous firing furnace by conveying the object to be processed, and the atmospheric temperature in the furnace changes. Further, the heated gas flows between the heat treatment zones as the processing object is conveyed, and the ambient temperature in each zone varies. This variation in the atmospheric temperature is noticeable for a certain period after the start of conveyance of the processing object. Conventionally, before the processing object is conveyed, a temporary processing object called a dummy is conveyed to stabilize the atmospheric temperature. After that, the glass substrate etc. which are the actual processing objects were conveyed.

Each heat treatment zone is temperature-controlled so that the ambient temperature at each position in the zone is stabilized near the set temperature. Each heat treatment zone has a heat generating part such as a heater, a muffle plate for dust-proofing the inside of the furnace and making the heat radiation into the furnace uniform, and a temperature detecting part such as a thermocouple for detecting the temperature of each zone Is provided, and the amount of heat generated by the heat generating unit is controlled so as to compensate for the variation in the ambient temperature based on the temperature detected by the temperature detecting unit (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2004-218156

  On the transport path side of the muffle plate in the furnace, the flow of the heated gas is intense and excessive temperature fluctuations occur. Therefore, it is difficult to stabilize the ambient temperature even if a temperature change on the conveyance path side from the muffle plate is detected and the heater is controlled.

  On the heater side of the muffle plate in the furnace, the heated gas hardly flows and the temperature fluctuation is gentle. Therefore, when the heater is controlled by detecting the temperature change on the heater surface from the surface of the muffle plate or the muffle plate, the ambient temperature is stabilized, but the control responsiveness to the sudden temperature change is not desirable.

  For example, when a plurality of processing objects are transported side by side in the width direction of the continuous firing furnace, the atmosphere in the furnace is partially overheated when an arrangement failure of a certain processing object occurs suddenly. For this reason, it is necessary to suppress the amount of heat generated by the heater in this part. The processing object may be burned excessively.

  An object of the present invention is to provide a continuous firing furnace having improved control responsiveness while stabilizing the ambient temperature.

The continuous firing furnace of the present invention includes a heat generating means, a muffle plate, a limiting means, a temperature detecting means, and a temperature control means. The heat generating means is provided in a furnace provided with a conveyance path. The muffle plate is provided between the conveyance path in the furnace and the heat generating means. The restricting means vents outside air into the furnace to restrict the flow of the heated gas along the transport direction of the transport path. The temperature detection means is disposed on the transport path side of the muffle plate in the furnace. The temperature control means controls the heat generation means based on the temperature detected by the temperature detection means. A plurality of temperature detection means and a plurality of heat generation means are arranged along a direction orthogonal to the conveyance direction of the conveyance path, and the temperature control means controls the heat generation means based on the detected temperature of the specific temperature detection means.

In this configuration, since the outside air is vented into the furnace by the restricting means, the flow of the heated gas in the transport direction is suppressed, and the fluctuation of the atmospheric temperature in the furnace is reduced. Therefore, in order to improve control responsiveness, the ambient temperature is stabilized even if the temperature detection means directly detects the ambient temperature on the transport path side of the muffle plate and controls the heating means. Also, a plurality of temperature detecting means and a plurality of heat generating means are arranged along a direction orthogonal to the transport direction of the transport path, and the heat control is controlled by the temperature control means based on the temperature detected by the specific temperature detecting means. By doing so, the atmospheric temperature of each position of the direction orthogonal to the conveyance path in a furnace can be equalize | homogenized.

  The limiting means is preferably a means for venting outside air into the furnace through a through hole provided in the furnace wall. Through the through hole provided in the furnace wall, the outside air can be vented into the furnace to restrict the flow of the heated gas in the conveying direction in the furnace.

  The conveyance path may include roller hearths arranged in the conveyance direction, and in this case, the through hole is an insertion hole of a rotation shaft of the roller hearth connected to a drive mechanism provided outside the furnace. Is preferred.

  According to this invention, since the flow of the heated gas in the conveying direction in the furnace is reduced, the atmosphere temperature on the conveying path side in the furnace is stabilized, and the control responsiveness is improved by directly detecting the atmosphere temperature. Can do. Therefore, the heat treatment of the processing object can be efficiently performed without necessarily transporting a large number of dummy substrates before the start of the transport of the processing object.

  Hereinafter, a configuration example of a continuous firing furnace will be described with reference to the drawings. 1 is a side sectional view of a roller hearth type continuous firing furnace, and FIG. 2 is a front sectional view of the continuous firing furnace.

  The continuous firing furnace 10 has a conveyance path for the substrate 100 that is a processing target. A plurality of heat treatment zones 12 are continuously arranged along the conveyance direction of the conveyance path (the direction indicated by the arrow X in FIG. 1). As the conveyance path, a plurality of rotatable rollers 15 are arranged along the conveyance direction X at equal intervals. The substrate 100 is transported through the plurality of heat treatment zones 12 in order by the rotation of the plurality of rollers 15. The substrate 100 is continuously transferred or tact transferred in each heat treatment zone 12.

  The furnace wall 11 of the continuous firing furnace 10 includes an upper wall surface 11A, a bottom wall surface 11B, and side wall surfaces 11C and 11D. A plurality of heaters 13 are arranged along the transport direction X on the upper wall surface 11 </ b> A and the lower wall surface 11 </ b> B of the furnace wall 11. The heater 13 is a heat generating means of the present invention. Each heat treatment zone 12 is heated to a predetermined heat treatment temperature set in advance by the heater 13.

  A heat insulating material 17 is installed at the boundary of the heat treatment zone 12 in each of the upper wall surface 11A and the lower wall surface 11B. The heat insulating material 17 suppresses heat conduction at the boundary of the heat treatment zone 12.

As shown in FIG. 2, muffle plates 16 </ b> A to 16 </ b> C are further provided in spaces surrounded by the furnace walls 11 </ b> A to 11 </ b> D. Substrate 100 in the space surrounded by the muffle plate 16A～16 C is conveyed. Muffle plate 16A～16 C is here constituted by heat resistant glass plate. In addition, you may comprise with a metal plate instead of a heat-resistant glass plate. The muffle plates 16 </ b> A to 16 </ b> C prevent dust generated from the wall surface of the furnace wall 11 from adhering to the substrate 100, and pass the radiant heat from the heater 13 to efficiently heat the atmosphere of the substrate 100.

  As shown in FIG. 1, a plurality of heaters 13 are arranged along the transport direction X. Further, as shown in FIG. 2, a plurality of heaters 13 are arranged along an orthogonal direction Y orthogonal to the transport direction X. A plurality of thermocouples 19 are also arranged along the transport direction X and the orthogonal direction Y. In this example, four heaters 13 and three thermocouples 19 are arranged along the orthogonal direction Y.

  The thermocouple 19 is connected to the controller 21 via a pipe 22. The controller 21 controls the amount of heat generated by each heater 13 based on the temperature in the muffle detected by a specific thermocouple 19 corresponding to the heater 13.

Further, the roller 15 extends along the orthogonal direction Y, and both end portions thereof are retracted out of the furnace through the through holes 20 provided in the side wall surfaces 11C and 11D and the muffle plate 16C .

Here, the through-hole 20 is provided in the part where the side walls 11C and 11D and the muffle plate 16C and the roller 15 intersect.

  Since the through hole 20 is provided in this way, if there is a flow of heated gas between each of the plurality of heat treatment zones 12, that is, along the transport direction X, between that and the inside of the furnace. The heated gas is discharged through the through hole 20 and the outside air is sucked.

Accordingly, the flow of the heated gas along the transport direction X is suppressed from propagating through each heat treatment zone, and the variation in the ambient temperature of each heat treatment zone is suppressed. Thereby, even if the thermocouple 19 is arranged in the space surrounded by the muffle plates 16A to 16C , the temperature in the muffle can be stabilized by the control of the heater 13 by the controller 21.

  Here, an experimental result in which a glass substrate is baked in this configuration is shown. FIG. 3 is a graph showing the time change of the ambient temperature. In the figure, the vertical axis indicates the ambient temperature of the object to be processed, and the horizontal axis indicates the elapsed time. This configuration example is shown in FIG. The comparative example which provided the thermocouple in the heater side rather than the muffle in the same figure (B) is shown.

  In any of the examples, the processing object is not first transported for a certain period, and thereafter, a plurality of processing objects are transported continuously. In addition, three temperatures in the orthogonal direction in each of the three consecutive heat treatment zones (ZONEs 11 to 13) are shown.

  In this configuration example shown in FIG. 5A, the atmospheric temperature in each of the heat treatment zones (ZONEs 11 to 13) is stable at the set temperature during the period in which the initial processing object is not conveyed. Thereafter, the substrates are sequentially loaded into the respective zones, and the respective ambient temperatures decrease, but immediately recover to the set temperatures. Since the ambient temperature recovers to the preset temperature before the next substrate is carried in, baking can be performed from the first substrate in the ambient at the preset temperature.

  On the other hand, in the comparative example shown in FIG. 5B, the atmospheric temperature in each of the heat treatment zones (ZONEs 11 to 13) is stable at an initial temperature higher than the set temperature during a period in which the original processing object is not conveyed. ing. However, when the first substrate is loaded into each zone, the ambient temperature decreases, and before the next substrate is recovered to the initial temperature, the next substrate is loaded and the ambient temperature gradually decreases. Then, only after a certain number of substrates (11 substrates in this example) have passed, the ambient temperature stabilizes near the set temperature, and firing can be performed from the subsequent substrate in the set temperature atmosphere.

  As described above, in this configuration example, baking can be performed at a set temperature from the first substrate that is carried in, and a fixed number of dummy substrates is not required as in the comparative example. Therefore, firing can be performed with high efficiency.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

It is side surface sectional drawing which shows an example of the continuous baking furnace which concerns on embodiment of this invention. It is front sectional drawing of the same furnace. It is sectional drawing explaining the temperature change in the furnace in the experiment example of board | substrate baking.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Furnace wall 12 ... Heat processing zone 13 ... Heater 15 ... Roller 16 ... Muffle plate 17 ... Heat insulation material 19 ... Thermocouple 20 ... Through-hole 21 ... Controller 22 ... Piping 100 ... Substrate

Claims (3)

Heating means provided in a furnace having a conveying path;
A muffle plate provided between the conveying path in the furnace and the heating means;
Limiting means for venting outside air into the furnace and restricting the flow of the heated gas along the transport direction of the transport path;
A temperature detecting means disposed on the side of the conveying path from the muffle plate in the furnace;
Temperature control means for controlling the heating means based on the temperature detected by the temperature detection means;
Equipped with a,
A plurality of the temperature detection means and a plurality of the heat generation means are arranged along a direction orthogonal to the transport direction of the transport path,
The temperature control means controls the heat generating means based on the temperature detected by the specific temperature detecting means.
Continuous firing furnace. The continuous firing furnace according to claim 1 , wherein the limiting means is means for ventilating outside air into the furnace through a through hole provided in the furnace wall. The transport path is configured to include roller hearts arranged in the transport direction,
The continuous firing furnace according to claim 2 , wherein the through hole is an insertion hole of a rotating shaft of the roller hearth connected to a driving mechanism provided outside the furnace.

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