JP2007212052A - Heat treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform heat treatment in a setter-less system while actualizing inexpensive, early and accurate detection of the occurrence of cracking in a treated object in a furnace. <P>SOLUTION: Part of each of a plurality of heat resistant glasses 32 arranged under a carrying roller 2 along a carrying passage is exposed as an exposed part 5 to the outside of the furnace, and a vibration sensor 4 is arranged on the exposed part 5. In accordance with a detection signal from the vibration sensor 4, the fall of part of a carried object on the heat resistant glass 32 due to the occurrence of cracking is detected. At this time, the rotation of the carrying roller 2 is stopped. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat treatment apparatus for performing heat treatment such as heat treatment, slow cooling treatment, and cooling treatment on a flat and brittle object such as a glass substrate for plasma display in a hollow conveyance path.

  A setter method is known as a heat treatment method for a flat and brittle object such as a glass substrate for plasma display. In setter-type heat treatment, an object to be processed is placed on a base plate of a strong heat-resistant thick plate called setter glass, and conveyed to a conveyance path in a furnace by rotation of a plurality of conveyance rollers (for example, patents) Reference 1).

  For example, a setter glass having a width of about 1600 mm, a length of 1200 mm, and a thickness of about 5 mm is used for heat treatment of a glass substrate having an object to be processed having a width of 1460 mm, a length of 1030 mm, and a thickness of 2.8 mm.

  In the setter method, since it is necessary to heat and cool even the setter glass having a larger heat capacity than the object to be processed, the energy consumption is large and the heating and cooling region is also long.

Therefore, in order to meet demands for energy saving and downsizing, setterless heat treatment without using setter glass has been proposed. In the setterless heat treatment, the workpiece is directly placed on the transport roller and transported, so that it is not necessary to heat and cool the setter glass having a large heat capacity, energy consumption is reduced, and the heating and cooling regions can be shortened.
JP 2004-293877 A

  A flat plate-like workpiece such as a glass substrate may be cracked in a furnace during heat treatment. If cracks occur in the workpiece during heat treatment, the workpiece stays on the setter in the setter type heat treatment, but in the setterless type heat treatment, a part of the workpiece is moved downward between the plurality of transport rollers. Fall. When a part of the dropped processing object is larger than the distance from the inner member on the bottom surface to the conveying surface, the processing object is conveyed by protruding upward from the conveying surface between a plurality of conveying rollers. May interfere.

  For this reason, it is necessary to detect the occurrence of cracks in the furnace in the furnace at an early stage, stop the conveyance of the workpiece, and remove a part of the dropped workpiece. However, when optically detecting the fall of a part of the processed object that has cracked, the position and size of the part of the broken processed object are not constant. It is necessary to arrange a large number of sensors, resulting in an increase in cost. In some cases, the optical sensor cannot reliably detect the fall of a light-transmitting object to be processed such as a glass substrate.

  An object of the present invention is to provide a setterless type heat treatment apparatus capable of early and surely detecting occurrence of a crack of an object to be processed in a furnace at a low cost.

  The heat treatment apparatus of the present invention includes an outer wall member, a plurality of transport rollers, a plurality of inner members, an exposed portion, vibration detection means, and control means. The outer wall member covers the periphery of the conveyance path through which the workpiece is conveyed. The plurality of transport rollers are rotatably supported at a plurality of positions along the transport path. The plurality of inner members are disposed below the plurality of transport rollers along the transport path. The exposed portion penetrates the outer wall member from at least one of the plurality of inner members and is exposed to the outside. The vibration detecting means is disposed in the exposed portion, and detects the occurrence of vibration caused by a part of the workpiece being transported along the transport path falling on the inner member, and outputs a detection signal. The control means controls the driving of the transport roller based on the detection signal so as to prevent contact between a part of the processed object that has fallen and the processed object that is subsequently transported.

  In this configuration, a part of the inner member positioned below the plurality of transport rollers disposed along the transport path is exposed to the outside through the outer wall member, and the vibration detecting means is disposed in the exposed portion. ing. Therefore, when a crack occurs in the workpiece in the furnace and a part of the workpiece falls below the transport roller, vibration generated in the inner member due to contact with the part of the workpiece is exposed outside the furnace. It propagates to the part and is detected by the vibration detecting means. The driving of the conveying roller is controlled based on the detection signal of the vibration detecting means that detects the vibration, and contact between a part of the processing object that has dropped and the processing object that is subsequently transported is prevented.

  Further, at least a heating region, a slow cooling region, and a cooling region are provided along the conveyance path, and the exposed portion is provided in an inner member disposed in at least the slow cooling region among the plurality of inner members.

  In this configuration, the vibration generated in the inner member arranged at least in the slow cooling region is detected by the vibration detecting means at the exposed portion outside the furnace. Therefore, the vibration of the inner member is detected in the slow cooling region where the workpiece is likely to crack.

  Further, when the vibration detection unit detects the occurrence of vibration, the control unit stops driving the conveyance rollers arranged in the upstream side of the conveyance path with respect to the inner member that has generated vibration among the plurality of conveyance rollers. Can be.

  In this configuration, the conveyance of the object to be processed located upstream from the inner member that has generated vibration due to the drop of a part of the object to be processed that has been cracked is stopped, and a part of the object to be processed and the Contact with the workpiece to be conveyed is prevented, and damage to the workpiece is prevented from expanding.

  In addition, when the vibration detecting unit detects the occurrence of vibration, the control unit determines whether or not the dropped processing object is exposed to the upper surface side of the conveying roller based on the detection signal, and has dropped. The drive of the transport roller can be stopped only when it is determined that the workpiece has a size protruding above the transport surface.

  In this configuration, the driving of the transport roller is stopped only when it is determined that a part of the fallen object is exposed to the upper surface side of the transport roller. Accordingly, when a part of the processing object that has fallen is small and does not affect the processing object that is subsequently transported, the transport of the processing object is continued.

  According to the heat treatment apparatus of the present invention, the inner member is in contact with a part of the object to be processed by causing the object to be processed to crack in the furnace and a part of the object to be dropped below the conveying roller. Can be detected early and reliably at a low cost by the vibration propagated to the exposed portion outside the furnace. Further, by controlling the driving of the conveying roller based on the detection signal of the vibration detecting means that detects the vibration, it is possible to prevent a part of the processing object that has dropped from coming into contact with the processing object that is subsequently transported. Can do.

  1A and 1B are a side cross-sectional view and a front cross-sectional view of a main part showing a configuration of a heat treatment apparatus 10 according to an embodiment of the present invention. For example, the heat treatment apparatus 10 performs a setterless heat treatment on the glass substrate for plasma display, which is the workpiece 20. The heat treatment apparatus 10 includes outer wall members 11 to 14, a conveyance roller 2, heat resistant glasses 31 to 34, a vibration sensor 4, and a conveyance motor 24.

  The outer wall members 11 to 14 are made of a heat insulating material, and respectively cover the upper surface, the lower surface, and the left and right side surfaces of the conveyance path through which the workpiece 20 is conveyed. At least the outer wall member 11 includes a heater (not shown) on the inner surface. Each of the outer wall members 11 to 14 is divided into a plurality along the conveyance path indicated by the arrow X.

  The heat-resistant glasses 31 to 34 are inner members of the present invention, and are arranged so as to cover the furnace inner surfaces of the outer wall members 11 to 14, respectively. The heat resistant glasses 31 to 34 prevent the dust that has detached from the outer wall members 11 to 14 from adhering to the workpiece 20. Each of the heat-resistant glasses 31 to 34 is divided into a plurality along the conveyance path.

  The transport roller 2 is provided at each of a plurality of positions along the transport path. Both ends of the transport roller 2 pass through the outer wall member 13 and the outer wall member 14 and the heat-resistant glass 33 and the heat-resistant glass 34, and are rotatably supported by bearings 21 and 22 outside the left side and right side furnaces. ing. A sprocket 23 is fixed to the transport roller 2 at the end exposed to the outside of the furnace on the right side. The rotation of the transport motor 24 is transmitted to the sprocket 23 via the chain 25.

  Each of the plurality of heat-resistant glasses 32 is not closely supported by the outer wall member 12, but is supported in a non-contact manner except for the lower part and the intermediate position of the outer wall members 13 and 14, so that vibration to other members is prevented. Vibration attenuation in the heat-resistant glass 32 (inner member) due to propagation is minimized. However, when vibration attenuation is not a problem, close support may be provided.

  An exposed portion 5 exposed from the left outer wall member 13 to the outside of the furnace is formed at the end on the left side of each of the plurality of heat resistant glasses 32. A vibration sensor 4 that is a vibration detecting means is attached to each of the exposed portions 5. The vibration sensor 4 detects vibration that has occurred in the heat-resistant glass 32 and then propagated to the exposed portion 5 and outputs a detection signal.

  FIG. 2 is a diagram illustrating an example of the contents of the heat treatment in the heat treatment apparatus 10. The heat treatment apparatus 10 conveys the workpiece 20 from one end to the other end of the conveyance path in the furnace, and performs a first soaking process, a second soaking process, a slow cooling process, and a cooling process on the workpiece 20 during this period.

  In the first soaking process, the state of heating the object 20 as an example to 350 ° C. is maintained for 20 minutes. In the second soaking process, the workpiece 20 is heated to 600 ° C. as an example and maintained for 30 minutes. In the slow cooling treatment, the workpiece 20 is cooled to 400 ° C. over 1 hour. In the cooling process, the object to be heated 20 is cooled to room temperature over about 50 minutes.

  FIG. 3 is a block diagram illustrating an example of the configuration of the control unit 6 of the heat treatment apparatus 10. The control unit 6 as control means of the present invention is configured by connecting an A / D converter 64, a motor driver 65, and the like to a CPU 61 having a ROM 62 and a RAM 63.

  The same number of A / D converters 64 as the vibration sensors 4 are provided, and the vibration sensors 4 are connected to each of the plurality of A / D converters 64. Each A / D converter 64 converts the detection signal of the vibration sensor 4 into digital data and inputs it to the CPU 61.

  The CPU 61 outputs drive data to the motor driver 65 in accordance with a program stored in the ROM 62 while referring to the detection data input from the A / D converter 64.

  A conveyance motor 24 is connected to the motor driver 65. The motor driver 65 drives the carry motor 24 based on the drive data output from the CPU 61.

  FIG. 4 is a flowchart showing the processing procedure of the CPU 61. During the heat treatment of the workpiece 20, the CPU 61 drives the transport motor 24 via the motor driver 65 (S1). Thereby, the workpiece 20 is transported along the transport path in the furnace.

  During the execution of the heat treatment, the CPU 61 determines whether any of the plurality of vibration sensors 4 has detected vibration (S2). When any of the vibration sensors 4 detects vibration, the CPU 61 stops driving the transport motor 24 (S3).

  When falling objects are removed and processing is instructed to restart, and when none of the plurality of vibration sensors 4 detects vibration, the conveyance motor 24 is driven until the end of processing is instructed. Conveyance of the processed product 20 is continued (S4, S5).

  The heat treatment apparatus 10 conveys the inside of the furnace by placing the workpiece 20 directly on the conveyance roller 2 without using a setter. When the workpiece 20 being transported in the furnace is cracked and a part thereof falls downward from the transport roller 2, a part of the workpiece 20 comes into contact with each other to generate vibration in the heat-resistant glass 32. Propagates to the exposed portion 5. Therefore, it can be determined that the workpiece 20 is cracked in a region where the heat-resistant glass 32 provided with the vibration sensor 4 that has detected the vibration is located in the exposed portion 5, and a part thereof has dropped from the transport roller 2.

  When the fallen object from the transport roller 2 is relatively large, a part of the fallen object continues to protrude upward from the transport surface, and if this is left unattended, it collides with the object 20 to be transported later. When any of the vibration sensors 4 detects vibration, the driving of the transport motor 24 is stopped to stop the movement of the workpiece 20 in the transport path, and the workpiece 20 to be transported later falls. It can be prevented from colliding with an object and being damaged.

  Note that the CPU 61 may be provided with display means, and the CPU 61 may display on the display means the location where the vibration sensor 4 that detects vibration is disposed. The position of the fallen object can be accurately identified to facilitate the removal work. Display means such as an indicator lamp may be provided in proximity to each of the vibration sensors 4, and display may be performed by display means closest to the vibration sensor 4 that has detected vibration.

  FIG. 5 is a diagram illustrating an example of an experimental result of a vibration detection state by the vibration sensor 4. As is apparent from the figure, the output voltage, which is the detection signal of the vibration sensor 4 disposed on the exposed portion 5 of the heat-resistant glass 32, increases as the pieces falling on the heat-resistant glass 32 increase. This output voltage is also greatly different from the output voltage of the vibration sensor 4 when an external force is applied to the entire heat treatment apparatus 10, when vibration is applied from the heat treatment apparatus 10 itself, or when fragments are dropped on the adjacent heat-resistant glass. .

  Therefore, it is possible to determine the size of the pieces dropped on the heat-resistant glass 32 having the exposed portion 5 to which the vibration sensor 4 is attached from the output voltage of the vibration sensor 4.

  However, although the difference in output voltage due to the difference in processing temperature is small, the output voltage depends on various conditions such as the shape and thickness of the workpiece 20, the size and supporting state of the heat-resistant glass 32 on the bottom surface, and the drop height. Since it changes, an optimal threshold value is set as appropriate.

  When the fragments dropped from the object to be processed 20 are sufficiently small, they completely fall on the heat-resistant glass 32 and do not collide with the object to be processed 20 conveyed later. When the debris dropped from the object to be processed 20 is relatively large, a part protrudes above the conveying roller 2 and collides with the object 20 to be conveyed later.

  Therefore, only when it is determined from the output voltage of the vibration sensor 4 that the fragments are relatively large, the driving of the transport motor 24 may be stopped in S5. In the case where the crack generated in the workpiece 20 can interrupt the heat treatment only when the subsequent heat treatment of the workpiece 20 is hindered and does not affect the heat treatment of the subsequent workpiece 20. The heat treatment operation can be continued.

  Further, it can be accurately detected from the output voltage of the vibration sensor 4 that a broken piece has fallen on the heat-resistant glass 32 having the exposed portion 5 to which the vibration sensor 4 is attached.

  Therefore, the rotation of the transport motor 24 is supplied for each transport roller 2 included in each region obtained by dividing the transport path into a plurality of regions, and in the process of S5, the region where the vibration sensor 4 that detects the vibration is disposed. Alternatively, the rotation of only the transport roller 2 arranged in the upstream area may be stopped. By continuing the conveyance of the workpiece 20 on the downstream side of the region where the falling object exists, the workpiece 20 that does not collide with the falling object among the workpieces 20 being conveyed in the furnace. The heat treatment can be properly performed.

  In the above-described embodiment, it is not always required that one area including the plurality of transport rollers 2 driven in the same state matches the area where each vibration sensor 4 is disposed. Not. The arrangement position of the conveyance roller 2 and the arrangement position of the vibration sensor 4 can be set based on different references. In this case, a correspondence relationship between the arrangement position of the transport roller 2 and the arrangement position of the vibration sensor 4 is determined in advance, and driving should be controlled when any one of the vibration sensors 4 detects vibration according to this correspondence relationship. The upstream conveying roller 2 can be determined.

  Here, the upstream conveyance roller 2 means the conveyance roller 2 that is conveying another workpiece 20 that may be affected by a drop of a part of the workpiece 20, and is not necessarily the vibration sensor 4. It does not mean the position of the physical upstream side of the conveying roller 2 with respect to. Therefore, when a part of the workpiece 20 falls, the rotation of the transport roller 2 that is physically disposed on the downstream side with respect to the position where the vibration sensor 4 that has detected the vibration can be stopped.

It is side sectional drawing and front sectional drawing of the principal part which shows the structure of the heat processing apparatus 10 which concerns on embodiment of this invention. 3 is a diagram illustrating an example of the content of heat treatment in the heat treatment apparatus 10. FIG. 3 is a block diagram illustrating an example of a configuration of a control unit 6 of the heat treatment apparatus 10. FIG. It is a flowchart which shows an example of the process sequence of CPU61. It is a figure which shows an example of the experimental result of the detection state of the vibration by the vibration sensor.

Explanation of symbols

2 Transport roller 4 Vibration sensor (vibration detection means)
5 Exposed part 6 Control part (control means)
DESCRIPTION OF SYMBOLS 10 Heat processing apparatus 11-14 Outer wall member 20 To-be-processed objects 31-34 Heat-resistant glass (inner member)

Claims (4)

  An outer wall member that covers the periphery of the conveyance path through which the workpiece is conveyed, a plurality of conveyance rollers that are rotatably supported at each of a plurality of positions along the conveyance path, and the plurality of lines along the conveyance path A plurality of inner members disposed below the conveying roller, an exposed portion that penetrates the outer wall member from at least one inner member of the plurality of inner members and is exposed to the outside, and is disposed on the exposed portion A vibration detecting means for detecting the occurrence of vibration due to a part of the object to be processed being transported along the transport path being dropped on the inner member and outputting a detection signal; And a control means for controlling the driving of the conveying roller based on the detection signal so as to prevent contact between a part of the object and a workpiece to be conveyed thereafter.   It comprises at least a heating region, a slow cooling region, and a cooling region along the transport path, and the exposed portion is provided in at least an inner member arranged in the slow cooling region among the plurality of inner members. The heat treatment apparatus according to claim 1.   The control means includes a transport roller arranged in a range upstream of the transport path from the inner member that has generated the vibration among the plurality of transport rollers when the vibration detection means detects the occurrence of vibration. The heat treatment apparatus according to claim 1, further comprising a stop process for stopping the driving of the heat treatment apparatus.   The control means is configured such that when the vibration detection means detects the occurrence of vibration, a part of the workpiece that has fallen on any of the plurality of inner members based on the detection signal is on the upper surface side of the plurality of transport rollers. When determining whether or not a part of the processing object dropped by the determination process is exposed to the upper surface side of the plurality of conveying rollers. The heat treatment apparatus according to claim 3, further comprising a configuration for performing only the stop process.

Images