JP2007155260A - Continuous kiln - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous kiln equipped with a conveyance control means capable of preventing occurrence of warping caused by a work piece moving in a place having a large change in temperature gradient. <P>SOLUTION: The continuous kiln is equipped with a furnace main body having a heating part and a cooling part formed from the inlet to the outlet of the furnace, a conveyance means for conveying the work piece W to successively pass through the heating part and the cooling part, and a control means for controlling the conveyance means for performing high speed conveyance at least from before a time when the front part of the work piece W comes to the heating part inlet until the time when the rear part of the work piece W completely passes the heating part inlet, then performing low speed conveyance, and after that, performing high speed conveyance from before a time the front part of the work piece W comes to the heating part outlet until the end part of the work piece W completely passes the heating part outlet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a continuous firing furnace used in a firing process of a glass substrate or the like for manufacturing a flat display panel such as a plasma display panel.

  Conventionally, as this type of continuous firing furnace, a furnace body in which a heating part and a cooling part are formed from an inlet to an outlet in the furnace, a conveying means for conveying a work sequentially via the heating part and the cooling part, There is known one that includes a control unit that controls the transfer unit so that the transfer rate of the workpiece is constant from the entrance to the exit in the furnace (for example, see Patent Document 1).

In the conventional continuous firing furnace, the heating part inlet and the heating part outlet are places where the temperature gradient in the furnace changes greatly. When the workpiece moves in a place with such a temperature gradient, for example, when the front part of the work is in the heating part, but the rear part is outside the heating part, there is a large temperature difference between the front part and the rear part of the work. It will occur. This is a factor that causes the workpiece to warp.
JP 2003-28632 A

  An object of the present invention is to provide a continuous firing furnace capable of preventing the occurrence of warpage due to the workpiece moving in a place where the temperature gradient greatly changes.

  A continuous firing furnace according to the present invention includes a furnace main body in which a heating part and a cooling part are formed from an inlet to an outlet in the furnace, a conveying means for sequentially conveying a work through the heating part and the cooling part, and at least a heating part From the time before the front part of the work reaches the inlet until the rear part of the work has passed through the heating part inlet, it is set to high-speed transfer, and then after low-speed transfer, at least the front part of the work is at the heating part outlet. Control means is provided for controlling the conveying means so that high-speed conveyance is performed from the time before the end until the rear part of the work has passed through the heating part outlet.

  In the continuous firing furnace according to the present invention, the workpiece is transported at a high speed when the workpiece moves through the heating portion inlet and the heating portion outlet, where the temperature gradient changes greatly. Therefore, the temperature difference between the front part and the rear part of the workpiece can be minimized, and the warpage of the workpiece can be prevented.

  According to the present invention, it is possible to prevent the occurrence of warping due to the workpiece moving in a place where the temperature gradient greatly changes.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the following description, the term “front and back” refers to the direction in which the workpiece is conveyed and forward, and the opposite side to the rear.

  FIG. 1 shows a furnace body 1 extending in the front-rear direction, and a temperature profile in the furnace body superimposed thereon.

  The firing furnace includes a furnace body 1, transport means for transporting the workpiece in the furnace body 1, and control means for controlling the transport speed of the transport means.

  An inlet 2 is provided at the rear end of the furnace body 1 and an outlet 3 is provided at the front end. A heating part and a cooling part are formed in the furnace body 1 from the inlet 2 to the outlet 3. The heating unit is divided into a preheating zone, a main heating zone, and a slow cooling zone.

  The transport means includes a large number of horizontal transport rollers (see FIGS. 2 and 3) arranged in the furnace body 1 at regular intervals in the transport direction. By rotating the transport roller, a plate-shaped workpiece (sometimes including a setter) is transported forward.

  The heating part inlet indicated by the point I and the heating part outlet indicated by the point O are places where the change in temperature gradient is large. That is, the heating unit inlet I has a constant horizontal gradient at room temperature, but after the heating unit inlet I, it has an upper right temperature rising gradient corresponding to the preheating zone. On the other hand, although it is a right descending temperature drop gradient corresponding to the slow cooling zone before the heating part outlet O, after passing the heating part outlet O, it enters the cooling part and the gradient of the temperature drop becomes steep. .

FIG. 2 schematically shows a workpiece transfer operation in the vicinity of the heating section inlet I. The control means
A first sensor 11 and a second sensor 12 are provided. The first sensor 11 is installed before the boundary between the normal temperature zone and the preheating temperature zone. The second sensor 11 is installed on the downstream side of the boundary and slightly before the place substantially equal to the length of the workpiece W in the front-rear direction. Further, an upstream first roller group 21 and a downstream second roller group 22 are arranged across the boundary. The lengths of the roller groups 21 and 22 are substantially equal to the length of the workpiece W in the front-rear direction. The conveying speed of each of the roller groups 21 and 22 is switched between a high speed and a low speed by the control means.

  Until the first sensor 11 detects the presence of the workpiece, the front portion of the workpiece W carried into the furnace body 1 from the inlet 2 is conveyed at a low speed. The low speed conveyance speed is, for example, 50 mm / min. When the first sensor 11 detects the front portion of the workpiece W, the conveyance speed of the first roller group 21 and the second roller group 22 is switched to high speed immediately or after a predetermined delay time has elapsed. The high speed conveyance speed is 2500 to 4000 mm / min. However, it is not limited to this. When the conveyance speed is switched to a high speed, the workpiece W is quickly carried into the preheating zone. Until the second sensor 12 detects the workpiece W carried into the preheating zone, the workpiece W is conveyed at a high speed, but when the second sensor 11 detects the presence of the workpiece, the conveyance speed is immediately or predetermined After the delay time elapses, the speed is switched from high speed to low speed. Thereafter, the workpiece W is conveyed at a low speed in the heating section. However, it is not limited to this. There may be several combinations of switching from low speed to high speed and from high speed to low speed along the way. For example, the switching may be performed at the bending point of the temperature profile in FIG.

  FIG. 3 schematically shows a workpiece transfer operation in the vicinity of the heating unit outlet O. A third sensor 31 and a fourth sensor 32 are installed in the vicinity of the boundary between the slow cooling zone and the cooling zone, as in the vicinity of the boundary between the normal temperature zone and the preheating temperature zone. Similarly to the upstream first roller group 21 and the downstream second roller group 22, an upstream third roller group 41 and a downstream fourth roller group 42 are provided. When the third sensor 31 detects the presence of a workpiece in the front portion of the workpiece W that has been conveyed through the heating unit at a low speed, the upstream third roller group 41 and the downstream fourth roller group 42 may immediately or predetermined delay. After the elapse of time, the conveyance speed is switched to high speed. At this time, when the workpiece W is glass, the switching of the speed to the cooling unit reaches a temperature at which the rear end of the glass during the slow cooling does not affect the shrinkage of the glass (for example, 350 ° C. to 400 ° C. or less). Usually done later. Thereby, the workpiece | work W is rapidly transferred from the inside of a heating part to a cooling part. By the workpiece presence detection signal of the fourth sensor 32, the conveyance speed of the third roller group 41 and the fourth roller group 42 is switched to a low speed immediately or after a predetermined delay time has elapsed.

  In the above description, the furnace main bodies extend in one line in the front-rear direction, but the same applies to the case where the furnace main body is divided into two stages, for example, in the cooling section.

  Further, the conveying operation by the roller may be a continuous conveying method or a tact conveying method.

  In addition, although the two sensors detect the presence of a workpiece for switching the workpiece conveyance speed, the presence or absence of the workpiece may be detected using only one sensor.

It is a side view which shows the baking furnace by this invention with the temperature profile in a furnace. It is workpiece | work conveyance explanatory drawing of the heating part entrance vicinity of the baking furnace. It is workpiece conveyance operation explanatory drawing near the heating part exit of the same baking furnace.

Explanation of symbols

11, 12, 31, 32 sensors
21, 22, 41, 42 Roller group

Claims (1)

A furnace body in which a heating part and a cooling part are formed from the inlet to the outlet in the furnace, a transport means for transporting the work sequentially through the heating part and the cooling part, and at least the front part of the work is inserted into the heating part inlet. From the time before the end of the work until the rear part of the work has passed through the heating part entrance, the high-speed transport, and then the low-speed transport, and then the heating part at least from the time before the front of the work reaches the heating part outlet A continuous firing furnace provided with a control means for controlling the conveying means so as to perform high-speed conveyance until the rear part of the work has passed through the outlet.

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