WO2005103593A1

WO2005103593A1 - Continuous heat treatment apparatus and continuous heat treatment method

Info

Publication number: WO2005103593A1
Application number: PCT/JP2004/004482
Authority: WO
Inventors: Shohei Tsuji
Original assignee: Koyo Thermo Systems Co., Ltd.
Priority date: 2004-03-30
Filing date: 2004-03-30
Publication date: 2005-11-03

Abstract

A continuous heat treatment method for plate-like works capable of intermittently carrying the works through a raising step, a moving step, a stopping step, and a placing step in an apparatus for heat-treating the plate-like works. In the raising step, the works are floated without being moved in the lateral direction by blowing gas from a large number of jetting ports positioned so that the jetting directions thereof are gradually changed to the horizontal side toward the upper side to the lower surfaces of the works. In the moving step, the flow of the blown gas is increased more than that in the raising step to move the works in the lateral direction. Since the works are not laterally moved in raising and placing, the works can be prevented from being damaged by their rubbing against a receiving part.

Description

4 004482

I 1-Statement

Continuous heat treatment apparatus and continuous heat treatment method

Technical field

The present invention relates to a continuous heat treatment apparatus and a continuous heat treatment method suitable for heat treatment of a flat work, and can be used, for example, for firing a flat panel display panel member including a large-sized glass substrate.

Background art

For example, when firing a work including a large glass substrate for a plasma display panel, a roller hearth continuous firing furnace is currently exclusively used. In this conventional continuous firing furnace, the work is heat-treated while being conveyed by rollers while being held by a work holding member called a setting. By using such a setting, it is possible to prevent the contact surface of the workpiece with the roller from being damaged due to friction or sliding. However, since the setting has a larger size and weight than the work, it has a large heat capacity, so that unnecessary energy is wasted.

Therefore, it has been conventionally proposed that a heat treatment is performed while blowing the workpiece in a floating state by blowing a gas such as air on the lower surface of the workpiece (Japanese Patent Application Laid-Open No. 2000-71515, Japanese Patent Application Laid-Open No. 2002-2667368, Japanese Patent Application Laid-Open No. 9-132420, Japanese Patent Application Laid-Open No. 10-139160). In addition, a discharge port for the gas blown to the lower surface of the work is provided, and the number and opening of the discharge port is changed, so that the difference between the gas discharge flow rate from the discharge port and the gas discharge flow rate from the discharge port is improved. It has been proposed to levitate a work at a pressure corresponding to the pressure (Japanese Patent Application Laid-Open No. 9-132240).

Disclosure of the invention

However, when a work is transported in a floating state according to the conventional technique, it is not possible to sufficiently prevent the work from being damaged. For example, when performing a heat treatment of a large glass substrate or the like in a continuous heat treatment apparatus having a heat treatment zone of preheating, main firing, slow cooling, cooling, etc., the work is surely transported and uniformized. Since heat treatment is required under a uniform temperature condition, a method of intermittently transporting the work is adopted. When the work is conveyed intermittently, the work is placed on the receiving part at a predetermined heat treatment position, then transferred to the next heat treatment position and placed on the receiving part again. Therefore, when the work is placed in the receiving portion after being transported in a floating state, the contact surface of the work with the receiving portion may be scratched due to friction or slip due to inertia acting on the work. The prior art does not disclose any such problems or problem solving means. An object of the present invention is to provide a continuous heat treatment apparatus and a continuous heat treatment method that can solve such a problem. Furthermore, in the conventional technology that levitates the work with a pressure corresponding to the difference between the gas ejection flow rate from the gas outlet and the gas discharge flow rate from the discharge port, the control for changing the number and opening degree of the gas discharge port and the discharge port is required. Becomes complicated. Therefore, when the gas ejection flow rate changes, the gas blown to the work cannot be smoothly discharged from the discharge port, and as a result, the atmosphere around the work may be disturbed, and the yield may be reduced due to a decrease in cleanliness or temperature distribution. There is. Preferably, such a problem is also solved by the present invention. The present invention provides a heat treatment apparatus comprising: a receiving portion on which a plate-shaped work is placed; an ejection port for ejecting gas in a lateral direction as it goes upward; and a heater for heating the work. A continuous heat treatment method in which the workpiece is intermittently transported, wherein a gas having a set flow rate ejected from the ejection port is blown onto a lower surface of the work placed on the receiving portion, thereby forming the workpiece. A floating step for floating without moving in the lateral direction, and a flow rate of gas blown to the lower surface of the work floated without moving in the horizontal direction is set to a set flow rate larger than the set flow rate in the floating step, whereby the work A moving step of moving the workpiece in the horizontal direction in a floating state, and a gas flow rate blown to the lower surface of the work moving in the floating state is smaller than in the moving step. A floating flow rate by blowing the work from the lower surface onto the work levitated without moving in the lateral direction. A setting step of setting the flow rate smaller than that in the step, a mounting step of mounting the work on the receiving portion, wherein the floating step, the moving step, the stopping step, and the mounting step perform the work. Is transported.

According to the method of the present invention, the work placed on the receiving portion is lifted without moving in the lateral direction. After that, the work moving in the floating state is moved to the horizontal direction, and the work moving in the floating state is temporarily stopped without moving in the horizontal direction.Then, the flow rate of the gas blown to the lower surface of the work is reduced, and then the receiving part is moved to the receiving part. Since the work is placed, it is possible to reliably prevent the contact surface of the work with the receiving portion from being damaged due to friction or sliding. In the continuous heat treatment method of the present invention, it is preferable that the work is intermittently conveyed by repeating the floating step, the moving step, the stopping step, and the placing step in this order. Alternatively, it is preferable that the work is intermittently conveyed by alternately repeating the moving step and the stopping step between the floating step and the placing step. The continuous heat treatment apparatus of the present invention includes: a receiving portion on which a plate-shaped work is placed; a jet port for jetting gas in a horizontal direction as it goes upward; a heater for heating the work; and a jet port. A plurality of ejection flow passages which are alternatively communicated with each other and have different flow passage areas, a gas ejection source which is communicated with the ejection port via the ejection passage, and an ejection passage switching mechanism; The outlet is disposed at a position where the gas ejected from the ejection port can be blown onto the lower surface of the work placed on the receiving portion, and the ejection channel communicated with the ejection port is switched, whereby The flow rate of the gas ejected from the spout varies between a set flow rate at which the work is levitated without moving in the lateral direction and a set flow rate at which the work is moved in the horizontal direction in the floating state. According to the continuous thermal treatment apparatus of the present invention, the method of the present invention can be carried out. In the continuous heat treatment method according to the aspect of the invention, the heat treatment apparatus may further include: a plurality of ejection passages that are selectively communicated with the ejection outlet and have different passage areas, an ejection passage switching mechanism, and spraying on a lower surface of the work. A suction port for the gas, a plurality of suction flow paths that are selectively communicated with the suction port, and have a plurality of suction flow paths, and a suction flow path switching mechanism. Between the moving step and the moving step and the stopping step, when changing the flow rate of the gas ejected from the ejection port, communicates with the ejection port via the ejection channel switching mechanism. By switching the ejection flow path, the gas flow rate is changed, and in synchronization with the change in the gas flow rate ejected from the ejection port, the suction flow communicated with the suction port via the suction flow path switching mechanism. Cut the road By obtaining, it is preferable to vary the flow of gas sucked from the suction port Yes. As a result, when the gas ejection flow rate changes, the gas ejected from the ejection port is suctioned in a timely manner, the disturbance of the atmosphere around the work due to the gas blown to the work is suppressed, and a dustproof effect is achieved, and The yield can be improved by performing the heat treatment. In this case, in performing the continuous heat treatment method of the present invention, the continuous heat treatment apparatus of the present invention is selectively communicated with the suction port of the gas blown to the lower surface of the work and the suction port. A plurality of suction flow paths having different flow path areas, a gas suction source communicated with the suction port through the suction flow path, and a suction flow path switching mechanism; By switching the suction flow path that is communicated with the suction port via the suction flow path switching mechanism in synchronization with a change in the flow rate, the ejection flow is changed so as to change the gas flow rate sucked from the suction port. It is preferable to include a control device for controlling the flow path switching mechanism and the suction flow path switching mechanism. In this case, in the continuous heat treatment method of the present invention, the heat treatment apparatus includes: a circulation path for ejecting the gas sucked from the suction port from the ejection port; and a gas temperature adjustment device in the circulation path. In the above placement step, it is preferable to blow out a temperature-controlled air at a set flow rate without floating the work from the outlet. Thereby, the heat treatment of the work can be promoted. In this case, in performing the continuous heat treatment method of the present invention, the continuous heat treatment apparatus of the present invention includes a circulation path for ejecting the gas sucked from the suction port from the ejection port, Preferably, a temperature control device is provided, and the flow rate of the gas whose temperature is controlled by the temperature control device can be controlled to a set flow rate that does not cause the work to float. ADVANTAGE OF THE INVENTION According to this invention, it can prevent that a workpiece | work is damaged at the time of a continuous heat processing, and it becomes possible to perform more stable heat processing. Brief Description of Drawings

FIG. 1 is a configuration explanatory view of a continuous heat treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view for illustrating a partial configuration of the continuous heat treatment apparatus according to the embodiment of the present invention.

FIG. 3 is a front sectional view illustrating a partial configuration of the continuous heat treatment apparatus according to the embodiment of the present invention.

FIG. 4 is a cross-sectional plan view for illustrating a partial configuration of the continuous heat treatment apparatus according to the embodiment of the present invention.

FIG. 5 is a diagram showing an example of the relationship between time and work temperature in the continuous heat treatment method according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an example of a relationship between time and air ejection flow rate in the continuous heat treatment method according to the embodiment of the present invention.

FIG. 7 is a diagram showing an example of a relationship between time and a moving distance of a workpiece in the continuous heat treatment method according to the embodiment of the present invention.

The continuous heat treatment apparatus 1 shown in FIG. 1 has a plurality of receiving portions 4 on which a plate-shaped work 3 is placed in a furnace body 2. The receiving portions 4 are arranged side by side at intervals in the longitudinal direction of the furnace body 2. The longitudinal direction of the furnace body 2 is set as the transfer direction of the work 3 (the direction of the arrow α in FIG. 1). The longitudinal direction of each receiving part 4 is along the width direction of the furnace body 2. The interval between the receiving portions 4 is set so that the work 3 can be always supported by the plurality of receiving portions 4. In the present embodiment, the inside of the furnace body 2 is divided into a preheating zone 2a, a main firing zone 2b, a slow cooling zone 2c, and a cooling zone 2d in order from the entrance. Each zone 2a, 2b, 2c, 2d is divided into one or more temperature control blocks. The dimensions of the temperature control block in each of the zones 2 a, 2 b, 2 c, and 2 d in the work transfer direction are set so that the two works 3 can be placed on the receiving portion 4. Heaters 5 and 6 for heating the work 3 in the preheating zone 2 a and the main firing zone 2 b are provided for each temperature control block on the ceiling of the furnace body 2, and the air cooling type cooling device 7 in the slow cooling zone 2 c A water-cooled cooling device is provided for each temperature control block in the cooling zone 2d. In FIG. 1, the number of temperature control blocks is typically one. The inner surface of the furnace body 2 is preferably lined with heat-resistant glass or the like. A gas supply pipe 11 and a gas discharge pipe 12 are provided between the receiving portions 4 so as to have an axis along the width direction of the furnace body 2. The gas in the present embodiment is air. As shown in FIG. 2, each gas supply pipe 11 is provided with a plurality of injection ports 11A along the pipe axis direction. The direction of each of the ejection ports 11 A is set such that the gas is ejected in one lateral direction, which is the transport direction of the work 3, as going upward. In this embodiment, the gas supply pipe 11 The tip end opening of the frustoconical cylindrical body 11a extending from the periphery of the opening formed on the outer periphery is defined as a jet port 11A. Each of the ejection ports 11 A is arranged at a position where the gas ejected from the ejection port 11 A can be blown onto the lower surface of the work 3 placed on the receiving portion 4. Each of the gas discharge pipes 12 is provided with a plurality of suction ports 12A along the pipe axis direction. The direction of each suction port 12 A is such that the air blown to the lower surface of the work 3 by being ejected from the outlet 11 A is directed to the direction toward which the air is directed by changing the direction on the lower surface of the work 3. It is set. In the present embodiment, the suction port 12A is formed at the tip end of the inverted frustum-shaped cylindrical body 12a extending from the periphery of the opening formed on the outer periphery of the gas discharge pipe 12. Outside the furnace body 2, distribution ducts 20 corresponding to the respective temperature control blocks in the preheating zone 2a, the main firing zone 2b, the slow cooling zone 2c, and the cooling zone 2d are provided. Each distribution duct 20 is connected to a gas supply pipe 11 in a corresponding temperature control block via a branch pipe 20 '. Each distribution duct 20 is connected to a first blower 21 constituting a gas ejection source by a pipe via an electromagnetic first switching valve 22 constituting an ejection channel switching mechanism. Fig. 1 shows the first blower 21 and the first switching valve 22 corresponding to the distribution duct 20 in the main sintering zone 2b, but the other distribution ducts 20 are similarly connected to the first blower 21. 1 It is connected by piping via the switching valve 22. The first blower 21 is capable of sucking and discharging air at a constant flow rate. The first switching valve 22 has a first port S 2 a for communication with the distribution duct 20, a second port 22 b for communication with the discharge side of the first blower 21, and a first port S 2 a for communication with the first blower 21. It has a third port 22c for communication with the suction side, and a spool 22d that is selectively positioned between the floating transport position and the floating position. The spool 22d is provided with a first ejection channel 22d 'and a second ejection channel 22d' having a smaller channel area than the first ejection channel 22d '. Thereby, the flow path of the air jetted from the jet port 11A by the first switching valve 22 is switched. That is, when the spool 22 d is located at the floating transport position, the first port 22 a is communicated with the second port 22 b via the first ejection flow path 22 (Γ), and the third port 22 c is closed when spool 2 2 d is in the floating position The first port 22a is connected to the second port 22b via the second ejection flow path 22d ", and the third port 22c is connected to the second port 22b. The first ejection flow path 2 2 d ′ and the second ejection flow path 2 2 d ″ having different flow passage areas are connected to the distribution port 20, the branch pipe 20 ′, and the gas supply pipe 11 via the gas supply pipe 11. It is alternatively communicated with 1 A. In addition, the discharge side of the first blower 21 is communicated with the discharge port 11A via the first discharge flow path 22cT or the second discharge flow path 22d ". Preheating outside the furnace body 2 Collective ducts 30 corresponding to temperature control blocks in zone 2a, main firing zone 2b, slow cooling zone 2c, and cooling zone 2d are provided, and each collective duct 30 is provided in a corresponding temperature control block. Each of the collecting ducts 30 is connected to a second blower 31 constituting a gas suction source via a pipe, and is connected to a second gas discharge pipe 12 of the second blower 3 1. Is connected via a pipe to the electromagnetic second switching valve 32 that constitutes the suction flow path switching mechanism.Figure 1 shows the switching between the second blower 31 corresponding to the collecting duct 30 and the second switching in the main firing zone 2b. The valve 32 is shown, but the other collecting duct 30 is also connected to the second blower 31 via a pipe, and the second blower 31 is 2 It is connected via a pipe to the switching valve 32. The second blower 31 is capable of sucking and discharging air at a constant flow rate, and the second switching valve 32 is for gas discharge. A first port 32a, a second port 32b for communication with the discharge side of the second blower 311, and a third port 32c for communication with the suction side of the second blower 31; It has a spool 32d that is selectively positioned between the floating conveyance position and the floating position, and the spool 32d has a first suction flow path 32d 'and a first suction flow path 32d' that are smaller than the first suction flow path 32d '. The second suction flow path 32 d が having a small flow path area is provided, whereby the flow path of the air sucked from the suction port 12 A by the second switching valve 32 is switched. When the spool 3 2 d is located at the floating transfer position, the first port 32 a is connected to the second port 32 b via the first suction flow path 32 (Γ, and the third port 32 c is Will be closed. When the spool 3 2 d is in the floating position, the first port 32 a is communicated with the second port 32 b via the second suction flow path 32 d〃, and the third port 32 c is connected to the second port 32 b. Thus, the first suction flow path 32 d 'and the second suction flow path 32 d' having different flow path areas are connected to the collecting duct 30, the branch pipe 30 ′, It is alternatively connected to the suction port 12 A via the gas discharge pipe 12. Further, the suction side of the second blower 31 is connected to the first suction channel 3 2 d ′ or the second suction channel 3 2 d The gas is connected to the suction port 12 A through the ". The first port 32 a for discharging the gas of the second switching valve 32 is connected to the stainless steel heat resistant fiber dust filter 35 and the circulating air temperature controller 36. The suction side of the No. 1 blower 21 is connected via a pipe.The temperature control device 36 can be constituted by a heater at the position corresponding to the preheating zone 2a and the main firing zone 2b, and gradually cooled. At the position corresponding to zone 2c, it can be constituted by a cooling device such as an air-cooled pad ゃ air-cooled cooling coil, and at the position corresponding to cooling zone 2d, it can be constituted by a cooling device such as a water-cooled pad ゃ water-cooled cooling coil. Constitutes a circulation path for ejecting the air sucked from the suction port 12 A from the ejection port 11 A. The air in the circulation path is cleaned by the filter 35 and the temperature control device 36 The temperature is controlled by the temperature The joint device 36 has, for example, a thermocouple that detects the air temperature in the circulation path, and ejects from the ejection port 11A according to the difference between the detected temperature and the heat treatment temperature in the corresponding temperature control block in the heat treatment zone. In this embodiment, it is preferable that the piping constituting the circulation path be kept insulated by a heat insulating material. The temperature control device includes, for example, a thermocouple that detects the temperature of the upper surface of the receiving part 4. The temperature control device controls the temperature between the detected temperature and the heat treatment temperature in the temperature control block of the corresponding heat treatment zone. The temperature of the upper surface of the receiving part 4 is controlled in accordance with the difference, thereby facilitating the heat treatment in a state where the workpiece 3 is placed on the receiving part 4. The temperature control device includes the preheating zone 2a and the main firing zone 2 Corresponds to b At the position corresponding to the slow cooling zone 2c, it can be configured by a cooling device such as an air-cooled pad ゃ air-cooled cooling coil, and at the position corresponding to the cooling zone 2d, the water-cooled pad ゃ water-cooled It can be constituted by a cooling device such as a cooling coil etc. The first switching valve 22 and the second switching valve 32 are connected to the control device 40. The control device 40 includes the first switching valve 22 and the second switching valve. By controlling 32, the suction flow path communicated with the suction port 12A via the second switching valve 32 is synchronized with the stepwise change in the gas flow rate ejected from the ejection port 11A. The flow rate of the gas sucked from the suction port 12A is changed stepwise. That is, when the first ejection flow path 2 2 d ′ is connected to the ejection port 11 A via the first switching valve 22, the first suction is performed to the suction port 12 A via the second switching valve 32. When the flow path 3 2 d ′ is communicated and the second ejection flow path 2 2 d に is communicated with the ejection port 11 A via the first switching valve 22, the flow is switched via the second switching valve 32. The second suction channel 3 2 d "is connected to the suction port 12A. The second ejection channel 22d is connected to the ejection port 11A, and the second suction channel is connected to the suction port 12A. When 3 2 d 連 is connected, the flow rate of gas ejected from the outlet 11 A and the flow rate of gas sucked from the suction port 12 A are set so that the workpiece 3 can be levitated without moving laterally. In this case, the set flow rate of the gas ejected from the ejection port 11A is set to the suction port 12A so that the work 3 can be levitated by the air ejected from the ejection port 11A. Setting flow of air sucked from The set flow rate can be determined experimentally.

When the first outlet channel 2 2 d 'is connected to the outlet 11A and the first suction channel 32d' is connected to the suction port 12A, the gas discharged from the outlet 11A The flow rate and the flow rate of the gas sucked from the suction port 12 A are set flow rates at which the workpiece 3 can be moved in the horizontal direction in a floating state. In this case, the set flow rate of the gas ejected from the outlet 11 A is set so that the work 3 can be moved in the horizontal direction while floating by the air ejected from the outlet 11 A. The set flow rate of the gas sucked from 2 A is set to be larger than the set flow rate, and each set flow rate can be obtained experimentally.

As a result, the flow rate of the gas ejected from the ejection port 11A and the suction port 12 are changed by switching the ejection flow path communicating with the ejection port 11A and the suction channel communicating with the suction port 12A. The flow rate of gas sucked from A changes stepwise between the set flow rate that causes the workpiece 3 to levitate without moving laterally and the set flow rate that moves the workpiece 3 in the levitating state in one horizontal direction. . A pressure buffer 24 is provided at one end of the distribution duct 20 to absorb sudden pressure fluctuations at the time of switching the flow path by the first switching valve 22, and smoothly lift the work 3 and place it on the receiving part 4. Is achieved. Similarly, a pressure buffer may be provided at one end of the collecting duct 30. As shown in FIGS. 3 and 4, a plurality of rollers 51 having a vertical axis are rotatably supported via support members 50 provided in the furnace body 2. Rollers 5 1 are arranged in parallel along the longitudinal direction of furnace body 2 In addition, the transfer direction of the work 3 (the direction of the arrow / 3 in FIG. 4) is prevented from deviating from the transfer path along the longitudinal direction of the furnace body 2. The outer peripheral surface of the roller 51 is preferably made of ceramics such as alumina, zirconia, fused silica, and heat-resistant glass. As shown in FIG. 4, a plurality of detection sensors 52 for detecting the work 3 are attached to the furnace body 2. The sensors 52 are arranged at an interval in the conveying direction of the work 3 from each other. The sensor 52 of the present embodiment provides a detection signal of the work 3 when the light emitted from the light emitting element 52 a is not received by the light receiving element 52 b due to being blocked by the work 3 as shown by a dashed line in the drawing. Is output to the control device 40. The interval between adjacent sensors 52 is defined as the tact transport distance. The tact transfer distance is slightly larger than the dimension of the work 3 in the transfer direction. In the present embodiment, the dimension in the transport direction of each temperature control block in each of the zones 2a, 2b, 2c, and 2d is set to approximately twice the evening transport distance, and the receiving portion 4 of each temperature control block Two marks 3 can be placed simultaneously on each other. When the heat treatment is performed while the work 3 is being conveyed by the heat treatment apparatus 1, the work 3 is conveyed by the following levitating step, moving step, stopping step, and placing step. In the flotation process, the work 3 is levitated without moving laterally by blowing air at a set flow rate blown out from the spout 11A onto the lower surface of the work 3 placed on the receiving portion 4. That is, the control device 40 drives the first blower 21 at a constant speed, communicates the second ejection flow path 2 2 d ″ with the ejection port 11 A via the first switching valve 22, The blower 31 is driven at a constant speed, and the second suction flow path 32 d is connected to the suction port 12 A via the second switching valve 32. In the moving process, the air blows without moving laterally. The flow rate of the air blown to the lower surface of the work 3 is set to a flow rate larger than the flow rate set in the flotation process, thereby moving the work 3 in the floating state in one lateral direction. The blower 21 is driven at a constant speed, the first discharge passage 22 d 'is communicated with the jet port 11A via the first switching valve 22, and the second blower 31 is driven at a constant speed. The first suction flow path 32 d ′ is connected to the suction port 12 A via the second switching valve 32. In the stop process, the work 3 is levitated without moving in the lateral direction by setting the air flow rate blown to the lower surface of the work 3 moving in the floating state to a smaller set flow rate than in the moving process. That is, the control device 40 drives the first blower 21 at a constant speed, communicates the second ejection flow path 22 d〃 to the ejection port 11 A via the first switching valve 22, 31 is driven at a constant speed, and the second suction flow path 32 d is connected to the suction port 12 A via the second switching valve 32. In the placing process, the air flow blown from the lower surface to the work 3 levitated without moving in the lateral direction is set to a smaller flow rate than in the levitating process and the stop process, so that the work 3 receives the work 3 To be placed. In this levitation step, the controller 40 releases the drive of the first blower 21 and the second blower 31. Thus, in the present embodiment, the set flow rate of the air jetted from the jet port 11A in the mounting step becomes zero. The control device 40 switches the ejection flow path communicated with the ejection port 11A via the first switching valve 22 between the levitation step and the movement step and between the movement step and the stop step, Vent from the outlet 1 1 A The gas flow rate is changed stepwise. By synchronizing with the stepwise change of the gas flow rate spouting from the jet port 11A, the suction flow path communicated with the suction port 12A via the second switching valve 32 is switched, so that the suction port 1 Change the gas flow to be suctioned from 2 A in a step-like manner. Further, between the placing step and the floating step, and between the stopping step and the placing step, the control device 40 drives and blows the first blower 21 to release the air ejected from the ejection port 11A. Change body flow. In synchronization with the change in the flow rate of the gas ejected from the ejection port 11A, the flow rate of the gas sucked from the suction port 12A is changed by driving and releasing the drive of the second blower 31. The work 3 conveyed in the above-mentioned flotation step, moving step, stop step, and placing step passes through the preheating zone 2a, the main firing zone 2b, the slow cooling zone 2c, and the cooling zone 2d in order. In zones 2a, 2b, 2c and 2d, heat treatments of preheating, main firing, slow cooling and cooling are continuously performed. FIG. 5 shows an example of the relationship between the temperature and time of the work 3 to be heat-treated by the continuous heat treatment apparatus 1.The temperature of the work 3 gradually rises in the preheating zone 2a, and reaches the maximum temperature after the temperature rises in the main firing zone 2b. The temperature is gradually lowered in the slow cooling zone 2c and the cooling zone 2d. The work 3 is intermittently conveyed by the above-mentioned levitating step, moving step, stopping step, and placing step. For example, the work 3 can be transported intermittently by repeating the levitating step, moving step, stopping step, and placing step in this order. Further, the work 3 can be intermittently transported by alternately repeating the moving step and the stopping step between the floating step and the placing step. FIG. 6 shows an example of the relationship between the air ejection flow rate from the ejection port 11A and time, and FIG. 7 shows the relationship between the moving distance of the workpiece 3 and time corresponding to FIG. When the first blower 21 is driven at a constant speed, the flow rate corresponding to the flow area of the first ejection flow path 2 2 d ′ is set to H, and the flow area of the second The corresponding flow rate is indicated by L. In this case, at time t1, the ejection flow path communicating with the ejection port 11A is switched from the second ejection flow path 22d 2 to the first ejection flow path 22d '. At time t2, the flow rate of air ejected from the outlet 11A changes to H at time t2, and the ejected flow rate changes in a step-like manner. The jet channel 2 2 d 'is switched to the second jet channel 22 d'', and at time t4, the air jet flow from the jet 11A becomes L at time t4, and the jet flow changes stepwise. At time t5, the ejection flow path communicating with the ejection port 11A is switched from the second ejection flow path 22d〃 to the first ejection flow path 22d '. By repeating this, the moving process and the stopping process are alternately repeated. That is, the lateral movement of the work 3 is started between the times t1 and t2, the lateral movement of the work 3 is stopped between the times t3 and t4, and the work 3 is again moved after the time t5. The horizontal movement of 3 starts. When the acceleration of the work 3 increases in the moving process, the control of the transfer direction and the speed becomes unstable, so the time of the moving process is the maximum value at which a substantially linear relationship is established between the moving distance of the work 3 and the time. Is preferably obtained experimentally in advance, and the time is preferably equal to or less than the maximum value. Each time the work 3 is detected by each of the sensors 52, a placement process is performed through a stop process, and the work 3 is placed in the receiving portion 4. If the above-mentioned floating, moving, stopping, and placing steps are performed only one cycle in order to transport the work 3 by the tact transport distance corresponding to the interval between adjacent sensors 52, the time required for transporting Can be shortened. If the above-mentioned floating, moving, stopping, and placing steps are performed in a plurality of cycles in order to transport the work 3 by the evening transfer distance, the transfer direction and speed of the work 3 can be stabilized. Work 3 only for tact transfer distance When the workpiece is transported, the above-mentioned flotation process is performed at the beginning of the transport, then the moving process and the stopping process are repeated several times, and the workpiece 5 is moved by the tact transport distance and the workpiece 52 is detected by the sensor 52. When the mounting step is performed by using, the time required for the transfer can be reduced, and the transfer direction and speed can be stabilized. By setting the heat treatment time of the work 3 placed on the receiving portion 4 in each of the zones 2 a, 2 b, 2 c, and 2 d of the furnace body 2 longer than the transfer time of the work 3, A uniform heat treatment can be performed on the entire work 3. In addition, in each of the levitating process, moving process, stopping process, and placing process, the temperature of the air blown from the outlet 11A is adjusted by the temperature controller 36 to a temperature suitable for heat treatment according to the temperature set in the temperature control block. By doing so, heat treatment can be promoted. In the mounting process, air was blown from the outlet 11A at a flow rate that would not cause the workpiece 3 to float, and the air was adjusted to a temperature suitable for the heat treatment by the temperature control device 36. In this case, the control of the flow rate of the jet air from the jet port 11A can be performed by controlling the first blower 21 by the control device 40. According to the above-described embodiment, the work 3 placed on the receiving portion 4 is levitated without moving in the lateral direction, and then moved in the horizontal direction, and the work 3 moving in the floating state is temporarily moved in the horizontal direction. It is placed on the receiving part 4 by reducing the flow rate of air blown to the lower surface of the work 3 after that, it is placed on the receiving part 4 by reducing the flow rate of the air blown to the lower surface of the work 3 due to friction and slippage on the contact surface of the work 3 with the receiving part 4. It can be reliably prevented from being damaged. In addition, when the gas ejection flow rate changes, the gas ejected from the ejection port 11A is sucked in a timely manner from the suction port 12A, and the air blown to the workpiece 3 disturbs the atmosphere around the workpiece 3. The generation of dust is suppressed, the dust prevention effect is achieved, and the yield can be improved by performing stable heat treatment. The present invention is not limited to the above embodiment. For example, a third ejection passage having a smaller passage area than the second ejection passage 22 d 2 is provided, and a three-position switching valve is used instead of the first switching valve 22 as the ejection passage switching mechanism. Alternatively, in the mounting step, the first blower 21 and the ejection port 11A may be communicated via the third ejection channel. Further, the gas ejected from the ejection port is not limited to air, and an inert gas such as nitrogen may be ejected. The gas ejection source is not limited to a blower, and for example, a pressurized gas storage tank may be used. The continuous heat treatment apparatus only needs to have at least a heater for heating the work. Further, the present invention can be implemented without a suction port.

Claims

The scope of the claims

1. In a heat treatment apparatus comprising: a receiving portion on which a plate-shaped work is placed; a jet port for jetting gas in a horizontal direction as it goes upward; and a heater for heating the work, A continuous heat treatment method in which heat treatment is carried out intermittently,

A flotation step of causing the work to levitate without moving in the lateral direction by spraying a set flow rate of gas ejected from the jet port on the lower surface of the work placed on the receiving portion; Moving the workpiece horizontally in a floating state by setting the flow rate of the gas blown to the lower surface of the floated work to be higher than the set flow rate in the flotation step;

A gas flow blown to the lower surface of the work moving in a floating state, by setting a smaller flow rate than in the moving step, a stop step of floating the work without laterally moving;

By setting the flow rate of the gas blown from the lower surface to the work floated without moving in the lateral direction to a lower set flow rate than in the floating step and the stop step, the work for placing the work on the receiving portion is set. And a placement process,

A continuous heat treatment method for transporting the workpiece by performing the floating step, the moving step, the stopping step, and the placing step.

2. The continuous heat treatment method according to claim 1, wherein the work is intermittently conveyed by repeating the floating step, the moving step, the stopping step, and the placing step in this order.

3. The continuous heat treatment method according to claim 1, wherein the work is intermittently transferred by alternately repeating the moving step and the stopping step between the floating step and the placing step.

4. The heat treatment apparatus includes: a plurality of ejection passages having different passage areas that are selectively communicated with the ejection outlets; an ejection passage switching mechanism; And a plurality of suction channels having mutually different channel areas that are selectively communicated with the suction port, and a suction channel switching mechanism, At least between the floating step and the moving step and between the moving step and the stopping step, when changing the flow rate of the gas jetted from the jet port, the jet port through the jet channel switching mechanism; Changing the gas flow rate by switching the ejection flow path communicated with

By synchronizing with the change in the flow rate of the gas ejected from the jet port, by switching the suction flow path communicated with the suction port via the suction flow path switching mechanism, the gas flow rate sucked from the suction port is changed. 2. The continuous heat treatment method according to claim 1, wherein the temperature is changed.

5. The heat treatment apparatus includes: a circulation path for ejecting the gas sucked from the suction port from the ejection port; and a temperature control device for the gas in the circulation path.

5. The continuous heat treatment method according to claim 4, wherein in the placing step, temperature-regulated air having a set flow rate that does not cause the workpiece to float is ejected from the ejection port.

6. A receiving part for placing a plate-like work,

An ejection port for ejecting gas in a lateral direction as going upward,

A heater for heating the work,

A plurality of ejection flow paths having mutually different flow path areas that are selectively communicated with the ejection port, and a gas ejection source that is communicated with the ejection port via the ejection flow path,

An ejection channel switching mechanism,

The spout is arranged at a position where the gas ejected from the spout can be blown onto the lower surface of the work placed on the receiving portion,

By switching the ejection flow path communicated with the ejection port, the flow rate of the gas ejected from the ejection port is set at a flow rate that causes the work to float without moving in the lateral direction; A continuous heat treatment apparatus that changes between a set flow rate and a set flow rate.

7. A suction port for the gas blown to the lower surface of the work,

A plurality of suction channels different in flow channel area that are selectively communicated with the suction port, and a gas suction source that is connected to the suction port via the suction channel,

A suction channel switching mechanism, By synchronizing with the change in the flow rate of the gas ejected from the jet port, by switching the suction flow path communicated with the suction port via the suction flow path switching mechanism, the gas flow rate to be suctioned from the suction port is changed. 7. The continuous heat treatment apparatus according to claim 6, further comprising a control device that controls the ejection flow path switching mechanism and the suction flow path switching mechanism so as to change.

8. A circulation path for ejecting the gas sucked from the suction port from the ejection port, and a gas temperature adjustment device in the circulation path,

8. The continuous heat treatment method according to claim 7, wherein the flow rate of the gas whose temperature is adjusted by the temperature adjustment device can be controlled to a set flow rate that does not cause the work to float.