heating furnace

Abstract

To eliminate the need to switch between suction of gas from a heat treatment space to a gas line and jetting of the gas to the heat treatment space, or actualize longer switching timing.SOLUTION: A heating furnace 100 includes a body part 10 having a heat treatment space 11 for giving heat treatment to a treated object 1, and including a heat part arranged in the heat treatment space 11, a gas supply part for supplying gas required for the heat treatment to the heat treatment space 11 of the body part 10, a suction / jetting part 30 having a gas line 31 connected to the heat treatment space 11 of the body part 10 for continuously performing suction of gas from the heat treatment space 11 to the gas line 31 and jetting of the gas sucked into the gas line 31 to the heat treatment space 11, and a recuperator type heat exchanger 40 provided in the gas line 31 for making heat exchange between the gas sucked from the heat treatment space 11 and gas to be jetted to the heat treatment space 11, the gas line 31 being constructed so that the gas is not supplied from an outside excluding the heat treatment space 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a heating furnace. [Background Art]

[0002] A heating furnace that supplies gas into the furnace to perform heat treatment on an object to be processed is known.

[0003] As one of such heating furnaces, Patent Document 1 discloses a heating furnace in which gas inside the furnace is introduced into an external circulation path by a circulation fan, and the gas introduced into the external circulation path is returned to the furnace again. A heat accumulator for performing heat exchange with gas and a flow path switching device are provided in the external circulation path. The flow path switching device periodically switches the flow direction of gas flowing through the external circulation path, whereby the gas introduced from the furnace into the external circulation path undergoes heat exchange in the heat accumulator to be cooled to a low temperature, and the gas returned to the furnace undergoes heat exchange in the heat accumulator to be heated to a high temperature before being ejected into the furnace. According to such a configuration, the heating furnace described in Patent Document 1 is described as being capable of supplying a high-temperature, strong circulating flow into the furnace. [Prior Art Literature] [Patent Literature]

[0004] [Patent Literature 1] Japanese Unexamined Patent Publication No. 9-178112 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] As described above, in the heating furnace described in Patent Document 1, since heat storage and heat release are alternately performed by the heat accumulator provided in the external circulation path, it is necessary to switch between gas suction and gas ejection in a short cycle of about 5 seconds to 10 seconds due to heat exchange characteristics. For this reason, the service life of the flow path switching device for switching the flow between gas suction and ejection is shortened.

[0006] The present invention aims to solve the above problems and to provide a heating furnace that eliminates the need to switch between drawing gas from the heat treatment space of the main body to the gas line and ejecting gas from the gas line to the heat treatment space, or that allows for a longer timing of the above switching. [Means for solving the problem]

[0007] The heating furnace of the present invention A main body having a heat treatment space for heat treatment of an object to be treated, and a heating unit disposed within the heat treatment space, A gas supply unit that supplies the gas necessary for heat treatment to the heat treatment space of the main body, A suction and ejection unit has a gas line connected to the heat treatment space of the main body, and continuously performs the suction of gas from the heat treatment space to the gas line and the ejection of the gas drawn into the gas line into the heat treatment space, A heat exchanger of the heat exchange type is provided inside the gas line for performing heat exchange between the gas drawn in from the heat treatment space and the gas ejected into the heat treatment space. Equipped with, The gas line is characterized in that it is configured so that gas is not supplied from outside the heat treatment space. [Effects of the Invention]

[0008] The heating furnace of the present invention is equipped with a heat exchanger that is installed inside the gas line and performs heat exchange between the gas drawn in from the heat treatment space and the gas ejected into the heat treatment space. This allows for continuous drawing of gas from the heat treatment space into the gas line and continuous ejection of gas from the gas line into the heat treatment space. Therefore, it is basically not necessary to switch the direction of the gas flow through the gas line, and even if it is necessary to switch it, the timing of the switch can be extended. [Brief explanation of the drawing]

[0009] [Figure 1]This is a schematic cross-sectional view showing the configuration of the heating furnace in the first embodiment. [Figure 2] This is a schematic cross-sectional view showing the configuration of the heating furnace shown in Figure 1 when it is cut along the line II-II. [Figure 3] This is a schematic perspective view showing the configuration of a cooler using a compact heat exchanger. [Figure 4] This is a schematic perspective view showing the configuration of a heat exchanger. [Figure 5] This diagram illustrates the operation in the heating furnace according to the first embodiment, in which gas is drawn into the suction passage of the heat exchanger and ejected from the ejection passage. [Figure 6] This is a schematic cross-sectional view showing the configuration of the heating furnace in the second embodiment. [Figure 7] This diagram schematically shows the configuration of the heating furnace shown in Figure 6 when viewed from the direction of arrow Y1. [Figure 8] (a) is a diagram illustrating the operation in the continuous suction ejection mode of the heating furnace in the second embodiment, and (b) is a diagram illustrating the operation in the backwash mode. [Figure 9] This is a schematic cross-sectional view showing the configuration of the heating furnace in the third embodiment. [Figure 10] This figure shows the relationship between the unit vector along the direction of gas flow from the heat exchanger into the heat treatment space and the unit normal vector extending toward the side on which the object to be treated is placed, relative to the mounting surface of the plate on which the object to be treated is placed. [Figure 11] This is a schematic cross-sectional view showing the configuration of the heating furnace in the fourth embodiment. [Figure 12] This figure shows the relationship between the rotation speed of the first fan and the rotation speed of the backwash fan when the continuous suction / discharge mode and the backwash mode are alternately performed, where (a) shows the rotation speed when the duty cycle is 60% when the fan is driven by PWM control, and (b) shows the rotation speed when the duty cycle is 70%. [Figure 13] This is a schematic cross-sectional view showing the configuration of the heating furnace in the fifth embodiment. [Figure 14]It is a cross-sectional view schematically showing the configuration of the heating furnace in the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiments of the present invention are shown below to specifically describe the features of the present invention.

[0011] <First Embodiment> FIG. 1 is a cross-sectional view schematically showing the configuration of a heating furnace 100 according to the first embodiment. FIG. 2 is a cross-sectional view schematically showing the configuration of the heating furnace 100 shown in FIG. 1 when cut along line II-II. However, driving rollers 13, which will be described later, are omitted in FIG. 2.

[0012] Hereinafter, description is given on the assumption that the heating furnace 100 is a roller hearth furnace. A roller hearth furnace is a continuous heating furnace in which a plurality of driving rollers 13 are arranged at constant intervals along the traveling direction in the furnace, and conveys an object to be processed 1 on the driving rollers 13. FIG. 1 shows a cross-section of the heating furnace 100 cut along a plane perpendicular to the conveying direction of the object to be processed 1. However, the heating furnace 100 is not limited to a roller hearth furnace, and may be other types of heating furnaces such as a batch-type heating furnace.

[0013] The heating furnace 100 includes a main body 10, a gas supply unit 20, a suction and ejection unit 30, and a heat exchanger 40.

[0014] The main body 10 has a heat treatment space 11 for performing heat treatment on the object to be processed 1, and includes a heating unit 12 disposed in the heat treatment space 11. There are no particular restrictions on the shape or size of the main body 10. The heating unit 12 is, for example, a heater capable of heating up to about 1300°C. In the present embodiment, the driving roller 13 is disposed in the heat treatment space 11, and the heating unit 12 is located on the opposite side of the object to be processed 1 from the driving roller 13, that is, above the object to be processed 1, such that the object to be processed 1 is positioned between the driving roller 13 and the heating unit 12. However, the arrangement position of the heating unit 12 is not limited to the position on the opposite side of the object to be processed 1 from the driving roller 13.

[0015] In this embodiment, as shown in Figure 1, the main body 10 comprises four furnace walls: a first side wall 10a, a second side wall 10b, a hearth wall 10c, and a ceiling wall 10d. The first side wall 10a and the second side wall 10b, and the hearth wall 10c and the ceiling wall 10d, each face each other in a direction perpendicular to the transport direction of the workpiece 1. Also, as shown in Figure 2, both ends in the transport direction of the workpiece 1 are open and connected to an entrance / exit for the workpiece 1 to enter and exit. The furnace walls of the main body 10, including the first side wall 10a, the second side wall 10b, the hearth wall 10c, and the ceiling wall 10d, are made of, for example, an insulating material.

[0016] There are no restrictions on the type of workpiece 1 to be heat-treated; for example, it can be an unfired ceramic body for manufacturing chip-shaped ceramic electronic components such as multilayer ceramic capacitors. In this embodiment, a plate 2 on which multiple workpieces 1 are placed is transported on a drive roller 13. The plate 2 is made of, for example, ceramic.

[0017] The gas supply unit 20 supplies the gas necessary for heat treatment to the heat treatment space 11 of the main body 10. The main body 10 is provided with a gas supply port 14, and the gas supply unit 20 supplies the gas necessary for heat treatment to the heat treatment space 11 via the gas supply port 14.

[0018] Furthermore, the main body 10 is provided with a gas outlet 15 for discharging unnecessary gases so that the pressure in the heat treatment space 11 is kept constant.

[0019] The suction and ejection unit 30 has a gas line 31 connected to the heat exchanger 40, and continuously draws gas from the heat treatment space 11 into the gas line 31 and ejects the gas drawn into the gas line 31 back into the heat treatment space 11. In this embodiment, the direction of the gas flow through the gas line 31 does not change, and the suction of gas into the gas line 31 and the ejection of gas from the gas line 31 are performed continuously.

[0020] The gas line 31 is configured so that no gas is supplied from outside the heat treatment space 11. In other words, the gas drawn from the heat treatment space 11 into the gas line 31 is ejected directly into the heat treatment space 11 without being mixed with other gases or air. Therefore, the gas drawn into the gas line 31 by the suction ejection unit 30 and ejected into the heat treatment space 11 has the same composition as the gas inside the heat treatment space 11.

[0021] In this embodiment, the gas line 31 has a first extension 31a connected to the suction passage 41 of the heat exchanger 40 (described later), a second extension 31b connected to the discharge passage 42 of the heat exchanger 40, and a connecting portion 31c connecting the first extension 31a and the second extension 31b. In this embodiment, as shown in Figure 2, the first extension 31a and the second extension 31b each extend in a direction away from the main body 10, and the connecting portion 31c extends in a direction parallel to the first side wall 10a.

[0022] In this embodiment, the first extension portion 31a, the second extension portion 31b, and the connecting portion 31c are all located at the same height. That is, the gas line 31 is installed so that the gas flows horizontally.

[0023] In this embodiment, the suction discharge unit 30 includes a first fan 32a located in the gas line 31, and a second fan 32b located in the gas line 31 for directing the gas flow in the same direction as the gas flow caused by the first fan 32a. The first fan 32a is located in the first extension 31a of the gas line 31, and the second fan 32b is located in the second extension 31b. However, the suction discharge unit 30 may also consist only of the first fan 32a, omitting the second fan 32b.

[0024] The first fan 32a and the second fan 32b can each have any structure as long as they are capable of blowing air. In the following description, the first fan 32a and the second fan 32b may be collectively referred to as fan 32. Although not shown in the figures, the suction outlet 30 includes a control unit for controlling the driving of the first fan 32a and the second fan 32b.

[0025] The first fan 32a is positioned so that when driven, gas flows from the first extension 31a of the gas line 31 to the connection 31c. That is, when the first fan 32a is driven, gas is drawn from the heat treatment space 11 to the first extension 31a of the gas line 31 via the heat exchanger 40. At this time, the second fan 32b is also driven. The gas drawn from the heat treatment space 11 to the first extension 31a of the gas line 31 passes through the connection 31c and the second extension 31b and is ejected back into the heat treatment space 11 via the heat exchanger 40.

[0026] As described above, the second fan 32b is for directing the gas flow in the same direction as the gas flow caused by the first fan 32a. By providing the second fan 32b together with the first fan 32a, the gas suction and ejection operation can be performed more powerfully compared to a configuration with only the first fan 32a.

[0027] In this embodiment, the heating furnace 100 is located in the gas line 31 and includes a cooler 33 for cooling the gas that has been drawn in from the heat treatment space 11 and passed through the heat exchanger 40, which will be described later. The cooler 33 includes a first cooler 33a located in the first extension 31a of the gas line 31. The first cooler 33a is located upstream of the first fan 32a when the first fan 32a is driven. Upstream of the first fan 32a means upstream in the direction in which the gas flows when the first fan 32a is driven, and in Figure 2, this is the position closer to the heat exchanger 40 relative to the first fan 32a.

[0028] The first cooler 33a cools the gas drawn from the heat treatment space 11 through the heat exchanger 40 to the first extension 31a of the gas line 31. For example, the gas drawn from the heat treatment space 11 to the first extension 31a of the gas line 31 is cooled to about 100°C by the heat exchanger 40, and then cooled to below 50°C by the first cooler 33a. With such a configuration, it is possible to suppress the inflow of high-temperature gas into the first fan 32a and cause thermal damage.

[0029] Furthermore, the provision of the first cooler 33a allows the temperature distribution of the heat exchanger 40 to be maintained in equilibrium. In other words, if the first cooler 33a is not provided, the temperature of the heat exchanger 40 will rise during the continuous process of gas being drawn from the heat treatment space 11 to the gas line 31 and gas being ejected from the gas line 31 to the heat treatment space 11. In that case, the temperature of the gas cooled by the heat exchanger 40 may exceed 100°C.

[0030] However, in the heating furnace 100 of this embodiment, a first cooler 33a is provided, which suppresses the rise in temperature of the heat exchanger 40 as described above, and prevents the temperature of the gas that has passed through the heat exchanger 40 from exceeding 100°C.

[0031] As the first cooler 33a, for example, a known heat exchanger can be used. Figure 3 is a schematic perspective view showing the configuration of a cooler 33 (first cooler 33a) using a compact heat exchanger, which is one type of heat exchanger. As shown in Figure 3, the cooler 33 has a structure in which gas flow paths F1 through which high-temperature gas flows and refrigerant flow paths F2 through which refrigerant flows are alternately stacked. With such a structure, the gas flowing through the gas flow path F1 can be effectively cooled. The gas flow path F1 and the refrigerant flow path F2 are configured to be orthogonal to each other. Multiple fins are provided in the gas flow path F1 and the refrigerant flow path F2, and heat exchange takes place between the gas flowing through the gas flow path F1 and the refrigerant flowing through the refrigerant flow path F2.

[0032] Although Figure 3 shows a configuration in which two layers each of the gas flow path F1 and refrigerant flow path F2 are provided, the number of layers of gas flow path F1 and refrigerant flow path F2 is not limited to two.

[0033] The cooling function of the first cooler 33a will now be described. A refrigerant flows through the refrigerant flow path F2 to cool the gas flowing through the gas flow path F1. The refrigerant is, for example, cold air. For example, a cooling fan is installed upstream of the refrigerant flow path F2 to blow cold air into the refrigerant flow path F2. The gas that has passed through the heat exchanger 40 flows through the gas flow path F1.

[0034] As an example, let's assume that gas at approximately 100°C, drawn from the heat treatment space 11 and passing through the heat exchanger 40, flows into the gas flow path F1 of the first cooler 33a at an airflow rate of 30 L / min. If cold air at an airflow rate of 30 to 120 L / min is flowed as a refrigerant through the refrigerant flow path F2 of the first cooler 33a, the gas flowing through the gas flow path F1 will be cooled to approximately 50°C.

[0035] Furthermore, the first cooler 33a can be any cooler capable of cooling the gas, and is not limited to a heat exchanger with a structure in which gas flow paths F1 and refrigerant flow paths F2 are alternately stacked. Also, if the gas is sufficiently cooled by the heat exchanger 40, the cooler 33 can be omitted.

[0036] The heat exchanger 40 is installed inside the gas line 31 and is a heat exchange type heat exchanger that performs heat exchange between gas drawn in from the heat treatment space 11 and gas ejected into the heat treatment space 11. The heat exchanger 40 has a suction passage 41 through which the gas drawn in from the heat treatment space 11 flows, and an ejection passage 42 through which the gas ejected into the heat treatment space 11 flows.

[0037] Figure 4 is a schematic perspective view showing the configuration of the heat exchanger 40. As shown in Figure 4, the heat exchanger 40 has a structure in which suction passages 41 and discharge passages 42 are alternately stacked. The suction passages 41 and discharge passages 42 are configured to be parallel to each other. In the stacking direction, the suction passages 41 and discharge passages 42 are separated by a partition wall 43. Although Figure 4 shows a configuration in which two layers each of suction passages 41 and discharge passages 42 are provided, the number of layers of suction passages 41 and discharge passages 42 is not limited to two.

[0038] The heat exchanger 40 is located inside the main body 10 within the gas line 31, specifically in the region that penetrates the main body 10. In the examples shown in Figures 1 and 2, the heat exchanger 40 is located inside the gas line 31 in the region that penetrates the first side wall 10a of the main body 10. However, the heat exchanger 40 may also be located on the second side wall 10b side of the main body 10, or, as will be described later, on both the first side wall 10a side and the second side wall 10b side of the main body 10. By having the heat exchanger 40 located inside the main body 10 within the gas line 31, the temperature of the gas that passes through the heat exchanger 40 and is ejected into the heat treatment space 11 can be brought closer to the furnace temperature.

[0039] In Figures 1 and 2, the heat exchanger 40 is provided in the entire area of ​​the gas line 31 that penetrates the main body 10, but it may also be provided in only a part of the area that penetrates the main body 10. Furthermore, the heat exchanger 40 may be provided in a manner that extends from the area of ​​the gas line 31 that penetrates the main body 10 into the area outside the main body 10.

[0040] In Figures 1 and 2, the heat exchanger 40 is provided in the entire area of ​​the gas line 31 that penetrates the main body 10, but it may also be provided in only a part of the area that penetrates the main body 10. Furthermore, the heat exchanger 40 may be provided in a manner that extends from the area of ​​the gas line 31 that penetrates the main body 10 into the area outside the main body 10.

[0041] As shown in Figures 1 and 2, a heat exchanger 40, which performs heat exchange between the gas drawn in from the heat treatment space 11 and the gas ejected into the heat treatment space 11, is provided in the part of the gas line 31 located inside the main body 10. This allows the gas line 31 to be connected to the heat treatment space 11 at only one location. This configuration improves the flexibility of the gas line 31's installation compared to a configuration where the gas line 31 is connected to the heat treatment space 11 at two locations.

[0042] The suction passage 41 of the heat exchanger 40 is connected to the first extension 31a of the gas line 31, and the discharge passage 42 is connected to the second extension 31b of the gas line 31. The heat exchanger 40 is provided with multiple suction passages 41 arranged in layers, and all of the suction passages 41 are connected to the first extension 31a. In addition, the heat exchanger 40 is provided with multiple discharge passages 42 arranged in layers, and all of the discharge passages 42 are connected to the second extension 31b.

[0043] As shown in Figure 4, a portion of the ejection passage 42 is exposed within the heat treatment space 11 of the main body 10. The suction passage 41 is not exposed within the heat treatment space 11. This configuration makes it possible to suppress interference between the gas flow ejected from the heat exchanger 40 to the heat treatment space 11 and the gas flow drawn in from the heat treatment space 11 to the heat exchanger 40.

[0044] In other words, in a configuration where the discharge passage 42 is not exposed within the heat treatment space 11, the gas discharged from the heat exchanger 40 into the heat treatment space 11 is affected by the flow of gas drawn in from the heat treatment space 11, making it difficult for it to travel in a straight line. Specifically, a flow occurs where some of the gas discharged from the discharge passage 42 of the heat exchanger 40 into the heat treatment space 11 is immediately drawn into the suction passage 41.

[0045] However, as shown in Figure 4, since a portion of the ejection passage 42 is exposed within the heat treatment space 11 of the main body 10, gas is drawn into the suction passage 41 not only in the straight-ahead direction but also from the side of the partition wall 43 exposed within the heat treatment space 11. As a result, a portion of the gas ejected from the ejection passage 42 is prevented from flowing into the suction passage 41, making it easier for the gas ejected from the ejection passage 42 to travel in a straight line.

[0046] The inventors conducted simulations and found that if the length L1 of the ejection passage 42 exposed within the heat treatment space 11 is 1 / 2 or more of the widthwise dimension W1 of the heat exchanger 40, the interference between the ejection gas flow and the suction gas flow described above can be effectively suppressed. For example, if the widthwise dimension W1 of the heat exchanger 40 is 30 mm, it is preferable that the length L1 of the portion of the ejection passage 42 exposed within the heat treatment space 11 be 15 mm or more.

[0047] Furthermore, because a portion of the ejection passage 42 is exposed to the heat treatment space 11, heat exchange with the gas ejected into the heat treatment space 11 is promoted in the region where the ejection passage 42 is exposed to the heat treatment space 11, allowing gas at a temperature closer to the temperature inside the heat treatment space 11 to be ejected towards the workpiece 1.

[0048] Here, assuming the width dimension W1 of the heat exchanger 40 is 30 mm, the height H1 of the suction passage 41 and the discharge passage 42 is 1.5 mm, the thickness D1 of the partition wall 43 is 1 mm, the length L1 of the portion of the discharge passage 42 exposed into the heat treatment space 11 is 15 mm, the length L2 of the suction passage 41 and the discharge passage 42 is 200 mm, the suction passage 41 and the discharge passage 42 each have 7 layers, and the temperature of the heat treatment space 11 is 1200°C, the temperature of the gas discharged from the heat exchanger 40 into the heat treatment space 11 and the temperature of the gas drawn from the heat treatment space 11 and discharged from the suction passage 41 of the heat exchanger 40 to the first extension portion 31a of the gas line 31 were confirmed. Here, the gas flow rate through the gas line 31 was changed to 15 L / min, 30 L / min, and 45 L / min, and the above gas temperatures were confirmed. The results of the confirmation are shown in Table 1. In Table 1, "ejected gas temperature" is the temperature of the gas ejected from the heat exchanger 40 into the heat treatment space 11, and "exhaust gas temperature" is the temperature of the gas drawn from the heat treatment space 11 and discharged from the heat exchanger 40 to the first extension section 31a or the second extension section 31b of the gas line 31.

[0049] [Table 1]

[0050] As shown in Table 1, when the airflow rate of the gas flowing through the gas line 31 was 15 L / min, the temperature of the gas ejected from the heat exchanger 40 into the heat treatment space 11 was 1169°C, and the temperature of the gas flowing from the heat exchanger 40 to the first extension 31a of the gas line 31 was 81°C. Furthermore, when the airflow rate of the gas flowing through the gas line 31 was 30 L / min, the temperature of the gas ejected from the heat exchanger 40 into the heat treatment space 11 was 1140°C, and the temperature of the gas flowing from the heat exchanger 40 to the first extension 31a of the gas line 31 was 110°C. On the other hand, when the airflow rate of the gas flowing through the gas line 31 was 45 L / min, the temperature of the gas ejected from the heat exchanger 40 into the heat treatment space 11 was 1112°C, and the temperature of the gas flowing from the heat exchanger 40 to the first extension 31a of the gas line 31 was 138°C.

[0051] In other words, if the airflow rate of the gas flowing through the gas line 31 is 30 L / min or less, the temperature of the gas ejected into the heat treatment space 11 will be 1140°C or higher, and the difference between this temperature and the temperature of the gas in the heat treatment space 11 will be 60°C or less. That is, the temperature of the gas ejected from the heat exchanger 40 into the heat treatment space 11 is close to the temperature inside the furnace.

[0052] Furthermore, if the airflow rate of the gas flowing through the gas line 31 is 30 L / min or less, the temperature of the gas drawn from the heat treatment space 11 and passing through the suction passage 41 of the heat exchanger 40 will be 110°C or less. In this case, it is easy to lower the temperature of the gas to 60°C or less, which is the heat resistance temperature of the fan 32, using the cooler 33.

[0053] Therefore, under the conditions described above, it is preferable that the airflow rate of the gas flowing through the gas line 31 is 30 L / min or less.

[0054] Here, we will explain the operation of the suction nozzle 30 for drawing gas from the heat treatment space 11 to the gas line 31, and for ejecting gas from the gas line 31 to the heat treatment space 11.

[0055] As shown in Figure 5, when the first fan 32a and the second fan 32b are driven, the gas in the heat treatment space 11 of the main body 10 is drawn into the suction passage 41 of the heat exchanger 40. At this time, the cooling function of the first cooler 33a is turned on. The temperature of the gas in the heat treatment space 11 is assumed to be, for example, approximately 1200°C.

[0056] The gas drawn into the suction passage 41 of the heat exchanger 40 undergoes heat exchange with the gas flowing through the outlet passage 42, and its temperature drops to around 100°C. The gas that has passed through the suction passage 41 of the heat exchanger 40 is introduced into the first extension section 31a of the gas line 31 and is cooled to a temperature of 50°C or lower by passing through the gas flow path F1 of the first cooler 33a. The gas that has passed through the first cooler 33a flows through the connection section 31c of the gas line 31 into the second extension section 31b and is introduced into the outlet passage 42 of the heat exchanger 40.

[0057] The gas introduced into the discharge passage 42 of the heat exchanger 40 undergoes heat exchange with the gas flowing through the suction passage 41 and is heated to a temperature of approximately 1150°C, which is close to the temperature inside the heat treatment space 11. The gas that has passed through the discharge passage 42 is ejected into the heat treatment space 11 and reaches the surface of the multiple workpieces 1 on the plate 2.

[0058] In Figure 5, the direction of gas flow is indicated by arrows when gas is drawn from the heat treatment space 11 to the suction passage 41 of the heat exchanger 40, passes through the first extension section 31a, the connection section 31c, and the second extension section 31b of the gas line 31, and then ejected from the ejection passage 42 of the heat exchanger 40 back into the heat treatment space 11. In this way, the operation of gas being drawn from the heat treatment space 11 to the suction passage 41 of the heat exchanger 40, passing through the first extension section 31a, the connection section 31c, and the second extension section 31b of the gas line 31, and then ejected from the ejection passage 42 of the heat exchanger 40 back into the heat treatment space 11 is performed continuously.

[0059] In this case, if the workpiece 1 is an unfired ceramic body for manufacturing ceramic electronic components such as multilayer ceramic capacitors, heat treatment removes the binder and causes various reactions. The binder is, for example, carbon. For example, the binder in the ceramic body undergoes thermal decomposition at a temperature of around 150°C and is almost completely removed by the time the temperature exceeds 1000°C, but it is desirable to quickly remove any remaining components even at temperatures exceeding 600°C. For example, it is known that if the temperature in the furnace reaches its maximum temperature while the binder has not been completely removed, structural defects and a decrease in quality may occur in the manufactured ceramic electronic components. Therefore, it is important to remove the binder quickly.

[0060] Generally, since gas flow is effective in removing binders, it is desirable to supply gas with a sufficient flow rate to the vicinity of the object to be treated 1. By supplying gas with a sufficient flow rate to the vicinity of the object to be treated 1, the concentration of scattered gas containing scattered material from inside the object to be treated 1 decreases in its vicinity, and the removal of scattered material from inside the object to be treated 1 is promoted. Conversely, if the gas flow rate is low, the removal of scattered material from inside the object to be treated 1 will not proceed smoothly.

[0061] In the heating furnace 100 of this embodiment, the suction and ejection unit 30 continuously draws gas from the heat treatment space 11 to the gas line 31 and ejects the gas drawn into the gas line 31 back into the heat treatment space 11. This allows for the supply of gas at a sufficient flow rate to the vicinity of the workpiece 1 without the need to introduce new gas from outside the furnace into the gas line 31. Since the gas ejected from the gas line 31 into the heat treatment space 11 has the same composition as the gas inside the heat treatment space 11, it is possible to suppress the occurrence of reaction variations between the workpiece 1 at the location where the gas ejected from the gas line 31 hits and the workpiece 1 at the location where the gas ejected from the gas line 31 does not hit.

[0062] In this embodiment, the heating furnace 100 is equipped with a heat exchanger 40, which allows for continuous suction of gas from the heat treatment space 11 to the gas line 31 and continuous ejection of the gas drawn into the gas line 31 back into the heat treatment space 11. That is, the heat exchanger 40 is configured to perform heat exchange between the high-temperature gas drawn in from the heat treatment space 11 and the low-temperature gas ejected into the heat treatment space 11. Therefore, it is possible to suppress the rapid temperature rise or fall that occurs in a heat storage body that repeatedly performs heat storage and heat release, without switching the gas flow path. As a result, it is not necessary to switch the direction of the gas flow through the gas line 31, and thus it is not necessary to frequently switch the operation and stopping of the first fan 32a. This extends the lifespan of the first fan 32a.

[0063] <Second Embodiment> Figure 6 is a schematic cross-sectional view showing the configuration of the heating furnace 100A in the second embodiment. Similar to Figure 1, Figure 6 shows a cross-section of the heating furnace 100A when cut by a plane perpendicular to the conveying direction of the workpiece 1. Figure 7 is a schematic diagram showing the configuration of the heating furnace 100A shown in Figure 6 when viewed from the direction of arrow Y1. However, the heat exchanger 40 is omitted.

[0064] In the second embodiment, the heating furnace 100A further includes a backwashing fan 32c and a second cooler 33b compared to the configuration of the heating furnace 100 in the first embodiment. Also, as shown in Figure 7, a bypass passage 34 is provided in the gas line 31, and a check valve 50 is provided in the bypass passage 34.

[0065] The gas line 31 in this embodiment includes a portion that extends horizontally and a portion that extends vertically. That is, the gas line 31 has a shape similar to the gas line 31 shown in Figure 2, but bent upward at a point midway between the first extended portion 31a and the second extended portion 31b. The gas line 31 in this embodiment also includes the first extended portion 31a, the second extended portion 31b, and the connecting portion 31c, but the shapes of the first extended portion 31a and the second extended portion 31b are different from those of the gas line 31 shown in Figure 2.

[0066] In this embodiment, the first extension portion 31a has a first horizontal portion 31a1 which extends horizontally toward the outside of the main body portion 10, and a first vertical portion 31a2 which is connected to the first horizontal portion 31a1 and extends vertically.

[0067] In this embodiment, the second extension portion 31b has a second horizontal portion 31b1 which extends horizontally toward the outside of the main body portion 10, and a second vertical portion 31b2 which is connected to the second horizontal portion 31b1 and extends vertically.

[0068] The connecting portion 31c extends horizontally and connects the first vertical portion 31a2 of the first extension portion 31a and the second vertical portion 31b2 of the second extension portion 31b.

[0069] However, the first vertical portion 31a2 and the second vertical portion 31b2 do not necessarily have to extend in the vertical direction, and may be inclined with respect to the vertical direction. For example, the angle between the horizontal plane and the first vertical portion 31a2, and the angle between the horizontal plane and the second vertical portion 31b2 may be 60°.

[0070] The backwash fan 32c is located in the gas line 31 and is a fan that flows gas in the opposite direction to the gas flow driven by the first fan 32a. In the configuration example shown in Figure 7, the backwash fan 32c is located at the connection part 31c of the gas line 31. The backwash fan 32c can have any structure as long as it is capable of blowing air. However, the backwash fan 32c may have a lower output than the first fan 32a, and a fan with low static pressure characteristics can be used.

[0071] As shown in Figure 7, the first cooler 33a and the first fan 32a are located in the first vertical portion 31a2 of the first extension 31a of the gas line 31, which extends vertically. The first cooler 33a is located below the first fan 32a.

[0072] The second cooler 33b and the second fan 32b are located in the second vertical section 31b2 of the second extension section 31b of the gas line 31, which is the portion that extends vertically. The second cooler 33b is located in the second extension section 31b at a position upstream of the backwash fan 32c when the backwash fan 32c is driven, or more specifically, at a position upstream of the second fan 32b when the backwash fan 32c is driven. Note that "upstream" means the upstream side in the direction in which the gas flows. In this embodiment, the second cooler 33b is located below the second fan 32b in the second vertical section 31b2 of the gas line 31.

[0073] One end of the bypass channel 34 is connected to the first horizontal section 31a1, which is the horizontally extending portion of the first extension section 31a of the gas line 31, thereby connecting the first extension section 31a and the second extension section 31b. The position where the bypass channel 34 is connected to the first horizontal section 31a1 is close to the bottom surface of the first horizontal section 31a1. As shown in Figure 7, the bypass channel 34 is located below the connection section 31c.

[0074] The check valve 50, provided in the bypass flow path 34, is designed to allow gas to flow from the first extension section 31a to the second extension section 31b when it is open, but to prevent gas from flowing from the second extension section 31b to the first extension section 31a.

[0075] Now, let's explain the operation of the suction nozzle 30.

[0076] Figure 8(a) shows the gas flow when gas is continuously drawn from the heat treatment space 11 to the gas line 31 and then ejected back into the heat treatment space 11. Here, the operating mode in which the gas is continuously drawn in and ejected as described above is called the continuous draw-in and ejection mode. In the continuous draw-in and ejection mode, the first fan 32a and the second fan 32b are driven, while the backwash fan 32c is not driven. However, as with the heating furnace 100 in the first embodiment, the second fan 32b can be omitted.

[0077] In continuous suction and ejection mode, the cooling function of the first cooler 33a located in the first extension section 31a is turned on, and the cooling function of the second cooler 33b located in the second extension section 31b is turned off. In addition, the check valve 50 is kept closed.

[0078] When the first fan 32a and the second fan 32b are driven and the backwash fan 32c is dedriven, the gas in the heat treatment space 11 of the main body 10 is drawn into the suction passage 41 of the heat exchanger 40 and flows to the first extension 31a of the gas line 31. Because the check valve 50 is closed, no gas flows into the bypass passage 34. This prevents the generation of unnecessary circulation flow caused by gas flowing into the bypass passage 34, thereby preventing a decrease in the efficiency of gas suction and ejection.

[0079] The gas that has passed through the first extension 31a of the gas line 31 is introduced into the discharge passage 42 of the heat exchanger 40 through the connection 31c and the second extension 31b, and is then ejected into the heat treatment space 11. At this time, the cooling function of the second cooler 33b is turned off, so that the gas introduced into the discharge passage 42 of the heat exchanger 40 is not cooled more than necessary.

[0080] Here, the gas flowing through the gas line 31 is cooled by the first cooler 33a, which has its cooling function turned on. If the temperature of the cooled gas falls below the dew point, the water vapor contained in the gas condenses and adheres to the surface. As described above, since the first cooler 33a is located in the first vertical section 31a2 of the gas line 31, at least a portion of the condensed water adhering to the surface of the first cooler 33a can be allowed to fall off.

[0081] If operation continues in continuous suction and ejection mode, the amount of condensation adhering to the surface of the first cooler 33a increases, and the condensation that falls downward accumulates. Therefore, in the heating furnace 100A of this embodiment, a backwashing operation is performed to return the aforementioned condensation from the gas line 31 to the heat treatment space 11. Here, the operating mode in which the backwashing operation is performed is called the backwashing mode.

[0082] Figure 8(b) shows the gas flow during backwash mode. In backwash mode, the first fan 32a and the second fan 32b are deactivated, while the backwash fan 32c is activated. The cooling function of the first cooler 33a located in the first extension section 31a is turned off, and the cooling function of the second cooler 33b located in the second extension section 31b is turned on. The check valve 50 is in the open position.

[0083] When the first fan 32a and the second fan 32b are deactivated and the backwash fan 32c is activated, the gas in the heat treatment space 11 of the main body 10 is drawn into the outlet passage 42 of the heat exchanger 40 and flows to the second extension 31b of the gas line 31.

[0084] The gas introduced into the second extension section 31b is cooled by passing through the second cooler 33b. As described above, the backwashing fan 32c for performing the backwashing operation can be a lower-powered fan than the first fan 32a and the second fan 32b. Therefore, the amount of gas drawn from the heat treatment space 11 to the outlet passage 42 of the heat exchanger 40 during the backwashing operation is small, and the temperature of the gas flowing from the outlet passage 42 of the heat exchanger 40 to the second extension section 31b may be well below the heat resistance temperature of the first fan 32a and the second fan 32b. In that case, the second cooler 33b is unnecessary and can be omitted.

[0085] The gas that has passed through the second extension 31b of the gas line 31 is introduced into the suction passage 41 of the heat exchanger 40 through the connection 31c and the first extension 31a, and is ejected into the heat treatment space 11. At this time, the cooling function of the first cooler 33a is turned off, so it is possible to suppress the gas introduced into the suction passage 41 of the heat exchanger 40 from being cooled more than necessary.

[0086] As described above, since the check valve 50 is open, a portion of the gas flowing through the first extension section 31a passes through the bypass channel 34 and heads towards the second extension section 31b. This gas flowing through the bypass channel 34 (hereinafter referred to as the bypass flow) moves the condensation water adhering to the surface of the first cooler 33a and the condensation water accumulating below the first cooler 33a to the area below the second cooler 33b in the second extension section 31b. The diameter of the bypass channel 34 is large enough to ensure at least the bypass flow necessary to move the condensation water.

[0087] The backwashing operation described above is performed to move the condensed water present in the first extension 31a of the gas line 31 to the second extension 31b, and therefore only needs to be performed for a few seconds. Thus, after performing the backwashing operation for a few seconds, the continuous suction and ejection mode is resumed. The condensed water that has moved to the second extension 31b of the gas line 31 is ejected from the ejection passage 42 of the heat exchanger 40 into the heat treatment space 11 when the continuous suction and ejection mode begins.

[0088] The suction nozzle 30 periodically switches to backwash mode while operating in continuous suction nozzle mode. By periodically switching to backwash mode while operating in continuous suction nozzle mode, condensation water generated in the first extension portion 31a of the gas line 31 during operation in continuous suction nozzle mode can be returned to the heat treatment space 11. Furthermore, by returning the condensation water generated in the first extension portion 31a to the heat treatment space 11 by passing it through the bypass channel 34, it is possible to suppress the passage of condensation water through the fan 32. This reduces damage to the fan 32 caused by the accumulation of condensation water, etc.

[0089] The duration of the continuous suction and spray mode should be set according to the amount of condensation generated. That is, if the amount of condensation generated is small, the duration of the continuous suction and spray mode should be increased, and if the amount of condensation generated is large, the duration of the continuous suction and spray mode should be decreased. The ratio of the operating time in the continuous suction and spray mode to the total operating time in the backwash mode should be, for example, 60% or more.

[0090] As an example, in continuous suction and ejection mode, if the dew point of the gas drawn from the heat treatment space 11 to the suction passage 41 of the heat exchanger 40 at an airflow rate of 30 L / min is 60°C and cooled to 50°C in the first cooler 33a, the amount of condensation corresponds to 2.3 cc / min. Therefore, approximately 0.4 cc of condensation occurs in 10 seconds, adhering to the surface of the first cooler 33a, and at least a portion of it falls below the first cooler 33a and accumulates there. The above consideration is based on conditions that are quite prone to condensation, so it is generally considered that less than 1 cc of condensation per minute will occur.

[0091] In backwash mode, the gas flow rate through the bypass channel 34 is approximately 92 cc / second, given that the bypass channel 34 is 100 mm long, has a diameter of 3 mm, and the backwash fan 32c is driven at a static fan pressure of 184 Pa. Therefore, approximately 276 cc of gas flows through the bypass channel 34 in 3 seconds. As a result, the aforementioned 1 cc of condensation per minute can be sufficiently moved from the first extension 31a to the second extension 31b of the gas line 31 during the 3-second backwash operation.

[0092] Therefore, it is possible to set the continuous suction / ejection mode time to about 10 seconds to a few minutes, and the backwash mode time to about a few seconds. For this reason, the ratio of the continuous suction / ejection mode time to the backwash mode time can be set in a range of, for example, 3:1 to 100:1. In this case, the ratio of the operating time in the continuous suction / ejection mode to the total operating time in the backwash mode will be between 75% and 99%. In other words, the driving efficiency of the first fan 32a and the second fan 32b is high, between 75% and 99%.

[0093] It is also possible to configure the system without a check valve 50 in the bypass channel 34. For example, if the airflow rate of the gas drawn in during continuous suction and ejection mode is 500 cc / second, and the airflow rate of the gas flowing through the bypass channel 34 is 50 cc / second or less, then the amount of bypass flow is 1 / 10 or less of the amount of gas drawn in from the heat treatment space 11, so there is no practical problem even without a check valve 50.

[0094] <Third Embodiment> In the heating furnace 100 of the first embodiment, gas is ejected horizontally from the heat exchanger 40 into the heat treatment space 11. For this reason, it is preferable that the heat exchanger 40 be positioned at a height as close as possible to the drive roller 13 on which the plate 2 is placed, so that the gas is ejected toward the multiple objects 1 to be treated on the plate 2.

[0095] However, although not shown in Figure 1, the first side wall 10a of the main body 10 through which the gas line 31 passes is equipped with a drive unit such as a motor for driving the drive roller 13. Therefore, if the heat exchanger 40 is positioned at a height as close as possible to the drive roller 13, there is a possibility that the drive unit of the drive roller 13 and the gas line 31 may interfere with each other, requiring careful design.

[0096] Therefore, in the heating furnace 100B of the third embodiment, the heat exchanger 40 is located away from the drive unit of the drive roller 13.

[0097] Figure 9 is a schematic cross-sectional view showing the configuration of the heating furnace 100B in the third embodiment. Similar to Figure 1, Figure 9 shows a cross-section of the heating furnace 100B when cut by a plane perpendicular to the conveying direction of the workpiece 1.

[0098] Compared to the heating furnace 100 in the first embodiment, the heat exchanger 40 in this embodiment is located at a higher position relative to the drive roller 13, that is, at a position further away from the drive roller 13 in the height direction perpendicular to the conveying surface of the drive roller 13. Such an arrangement makes it possible to suppress interference between the drive unit of the drive roller 13 and the gas line 31.

[0099] In this embodiment, the heat exchanger 40 is positioned such that the dot product of the unit normal vector extending toward the side on which the workpiece 1 is placed and the unit vector along the direction of travel of the gas ejected from the heat exchanger 40 into the heat treatment space 11 is negative. This will be explained with reference to Figure 10.

[0100] Furthermore, since gas is ejected from the heat exchanger 40 in the direction in which the suction passage 41 and the ejection passage 42 extend toward the tip, the unit vector along the direction of travel of the gas ejected from the heat exchanger 40 to the heat treatment space 11 means the unit vector along the direction in which the suction passage 41 and the ejection passage 42 extend toward the tip.

[0101] Figure 10 shows the relationship between a unit vector v along the direction of gas flow from the heat exchanger 40 to the heat treatment space 11 and a unit normal vector n extending toward the side on which the object to be treated 1 is placed, relative to the mounting surface 2a of the plate 2 on which the object to be treated 1 is placed. The dot product (v·n) of the unit vector v and the unit normal vector n is negative. In other words, the orientation of the suction passage 41 and the discharge passage 42 of the heat exchanger 40 is adjusted so that the gas is ejected diagonally downward from the heat exchanger 40.

[0102] In the third embodiment, the heating furnace 100B can suppress interference between the drive unit of the drive roller 13 and the gas line 31. Furthermore, since gas is blown from diagonally above onto the multiple workpieces 1 on the plate 2 within the heat treatment space 11, it is possible to blow gas onto a larger number of workpieces 1. This promotes the reaction of a larger number of workpieces 1 and further suppresses variations in the reaction of each workpiece 1.

[0103] <Fourth Embodiment> Figure 11 is a schematic cross-sectional view showing the configuration of the heating furnace 100C in the fourth embodiment. The cutting position in the cross-sectional view shown in Figure 11 is the same as the cutting position in the cross-sectional view shown in Figure 2.

[0104] The heating furnace 100C in the fourth embodiment further includes a rotation speed measuring unit 60 compared to the configuration of the heating furnace 100 in the first embodiment. The rotation speed measuring unit 60 measures the rotation speed of the backwashing fan 32c, which is in a non-driven state, during continuous suction and ejection mode.

[0105] As described above, the backwashing operation is an operation to move condensed water present in the first extension portion 31a of the gas line 31 to the second extension portion 31b. Therefore, the backwashing fan 32c can be a fan with low static pressure characteristics that has lower output than the first fan 32a and the second fan 32b. When the fan with low static pressure characteristics is not driven, it rotates at a rotational speed corresponding to the airflow rate of the gas flowing through the gas line 31, due to the gas flowing through the gas line 31. For this reason, by measuring the rotational speed of the backwashing fan 32c in the non-driven state with the rotational speed measurement unit 60, it is possible to determine the airflow rate of the gas flowing through the gas line 31.

[0106] Figures 12(a) and (b) show the relationship between the rotation speed of the first fan 32a and the rotation speed of the backwash fan 32c when the continuous suction / ejection mode and the backwash mode are alternately performed. The operation time for the continuous suction / ejection mode was set to 25 seconds, and the operation time for the backwash mode was set to 5 seconds. Figure 12(a) shows the rotation speed when the duty cycle of the first fan 32a is set to 60% when driven by PWM control, and Figure 12(b) shows the rotation speed when the duty cycle is set to 70%. In Figure 12, PCnt1 is the rotation speed of the first fan 32a, and PCnt2 is the rotation speed of the backwash fan 32c.

[0107] As shown in Figure 12(a), when the duty cycle of the first fan 32a is set to 60% while driving with PWM control in continuous suction and ejection mode, the rotational speed of the backwash fan 32c is approximately 900 rpm. Also, as shown in Figure 12(b), when the duty cycle of the first fan 32a is set to 70% while driving with PWM control in continuous suction and ejection mode, the rotational speed of the backwash fan 32c is approximately 1080 rpm. The temperature of the gas flowing through the gas line 31 is almost constant, between 30°C and 50°C, and the rotational speed of the non-driven backwash fan 32c, as measured by the rotational speed measurement unit 60, corresponds to the airflow rate of the gas flowing through the gas line 31.

[0108] If the temperature of the gas in the heat treatment space 11 is changed, the temperature distribution of the gas flowing through the suction passage 41 and discharge passage 42 of the heat exchanger 40 will rise as the temperature of the gas in the heat treatment space 11 increases, and the pressure loss will change. In this case, even if the rotational speed of the first fan 32a in operation remains constant, the airflow rate of the gas flowing through the gas line 31 will change. For this reason, it is not possible to accurately determine the airflow rate of the gas flowing through the gas line 31 from the rotational speed of the first fan 32a in operation.

[0109] However, in the heating furnace 100C of this embodiment, the rotation speed of the non-driven backwashing fan 32c is measured by the rotation speed measuring unit 60, thereby enabling accurate determination of the airflow rate of gas flowing through the gas line 31. Furthermore, since the backwashing fan 32c can be used to determine the airflow rate of gas flowing through the gas line 31, there is no need to provide any other device for measuring the airflow rate. This simplifies the configuration of the heating furnace 100C, which is capable of determining the airflow rate of gas flowing through the gas line 31.

[0110] <Fifth Embodiment> Figure 13 is a schematic cross-sectional view showing the configuration of the heating furnace 100D in the fifth embodiment. The cutting position in the cross-sectional view shown in Figure 13 is the same as the cutting position in the cross-sectional view shown in Figure 2. The heating furnace 100D in the fifth embodiment, like the heating furnace 100C in the fourth embodiment, is equipped with a rotation speed measuring unit 60 and is characterized by the control of the control unit 35, which will be described later.

[0111] As shown in Figure 13, the suction discharge unit 30 includes a control unit 35 for controlling the driving of the first fan 32a and the second fan 32b. In this embodiment, the control unit 35 controls the driving of the first fan 32a and the second fan 32b in the driven state so that the rotational speed measured by the rotational speed measuring unit 60 matches the reference rotational speed. The reference rotational speed is set in advance, for example, to set the airflow rate of the gas flowing through the gas line 31 to a desired airflow rate. The control unit 35 matches the rotational speed measured by the rotational speed measuring unit 60 with the reference rotational speed, for example, by feedback control. By the control unit 35 controlling the driving of the driven fans 32 in the driven state so that the rotational speed measured by the rotational speed measuring unit 50 matches the reference rotational speed, it becomes possible to control the airflow rate of the gas flowing through the gas line 31 to a desired airflow rate even if the internal state of the gas line 31 changes, such as when foreign matter adheres to the inside of the gas line 31.

[0112] For example, the control unit 35 controls the PWM control output of the first fan 32a and the second fan 32b, which are in operation, so that the rotational speed measured by the rotational speed measuring unit 60 is 800 rpm. This allows the rotational speed of the backwash fan 32c, which is not in operation, to be controlled to remain approximately constant at 800 rpm, and thus the airflow rate of the gas flowing through the gas line 31 to remain constant.

[0113] In the control example described above, the rotation speed of the non-driven backwash fan 32c was set to 800 rpm. However, it is possible to control the rotation speed to any desired level as long as the airflow is greater than or equal to the airflow required for the non-driven backwash fan 32c to rotate stably, and the duty cycle of the PWM control of the driven first fan 32a and second fan 32b is within 100%.

[0114] <Sixth Embodiment> The heating furnaces 100 in the first embodiment to the heating furnace 100D in the fifth embodiment each have one suction nozzle 30. In contrast, the heating furnace 100E in the sixth embodiment has multiple suction nozzles 30. By providing multiple suction nozzles 30, it is possible to blow more gas onto the workpiece 1. This promotes the reaction on more workpieces 1 and further suppresses variations in the reaction for each workpiece 1.

[0115] Figure 14 is a schematic cross-sectional view showing the configuration of the heating furnace 100E in the sixth embodiment. The cutting position in the cross-sectional view shown in Figure 14 is the same as the cutting position in the cross-sectional view shown in Figure 2.

[0116] In the example shown in Figure 14, four suction nozzles 30 are provided. Specifically, two suction nozzles 30 are provided on the first side wall 10a side of the main body 10, and two suction nozzles 30 are provided on the second side wall 10b side facing the first side wall 10a. However, the number of suction nozzles 30 is not limited to four, and all of the suction nozzles 30 may be provided on a single side wall.

[0117] The present invention is not limited to the embodiments described above, and various applications and modifications can be made within the scope of the invention. For example, the characteristic configurations of the heating furnace in each embodiment can be combined as appropriate.

[0118] The shape of the main body 10 is not limited to the shape described in the above-described embodiment. For example, the shape of the main body 10 may be substantially spherical.

[0119] In the embodiments described above, the suction and ejection unit 30 is equipped with a fan 32, and the fan 32 is used to draw gas from the heat treatment space 11 to the gas line 31 and to eject gas from the gas line 31 to the heat treatment space 11. However, the power source for drawing in and ejecting gas is not limited to the fan 32.

[0120] The heating furnace in this application is as follows: <1> A main body having a heat treatment space for heat treatment of an object to be treated, and a heating unit disposed within the heat treatment space, A gas supply unit that supplies the gas necessary for heat treatment to the heat treatment space of the main body, A suction and ejection unit has a gas line connected to the heat treatment space of the main body, and continuously performs the suction of gas from the heat treatment space to the gas line and the ejection of the gas drawn into the gas line into the heat treatment space, A heat exchanger of the heat exchange type is provided inside the gas line for performing heat exchange between the gas drawn in from the heat treatment space and the gas ejected into the heat treatment space. Equipped with, The heating furnace is characterized in that the gas line is configured so that gas is not supplied from outside the heat treatment space. <2> The heat exchanger is characterized in that it is installed in a portion of the gas line that is located inside the main body. <1> The heating furnace described above. <3> The heat exchanger is characterized in that it is installed in the region of the gas line that penetrates the main body. <2> The heating furnace described above. <4> The heat exchanger has a suction passage through which gas drawn in from the heat treatment space flows, and an outlet passage through which gas ejected into the heat treatment space flows. The gas line is characterized by having a first extension connected to the suction passage of the heat exchanger, a second extension connected to the discharge passage of the heat exchanger, and a connecting portion connecting the first extension and the second extension. <1> ~ <3> A heating furnace as described in any one of the following. <5> A portion of the ejection passage is exposed within the heat treatment space of the main body. <4> The heating furnace described above. <6> The suction and ejection unit is characterized by comprising a first fan arranged in the gas line. <4> or <5> The heating furnace described above. <7> The suction discharge unit is further equipped with a second fan positioned in the gas line and for directing the gas flow in the same direction as the gas flow caused by the first fan. The first fan is located in the first extension, The second fan is characterized by being located in the second extension. <6> The heating furnace described above. <8> The gas line is further provided with a cooler for cooling the gas that has been drawn in from the heat treatment space and passed through the heat exchanger, The cooler is characterized in that it includes a first cooler positioned upstream of the first fan when the first fan is running. <6> or <7> The heating furnace described above. <9> The cooler is characterized by having a structure in which gas passages through which gas flows and refrigerant passages through which refrigerant flows are alternately stacked. <8> The heating furnace described above. <10> The gas line includes a portion that extends horizontally and a portion that extends vertically. The cooler is characterized in that it is positioned in the portion of the first extension of the gas line that extends in the vertical direction. <8> or <9> The heating furnace described above. <11> The gas line is provided with a bypass channel, one end of which is connected to the horizontally extending portion of the first extension, connecting the first extension and the second extension. The suction and ejection unit is further characterized by being positioned in the gas line and comprising a backwashing fan for flowing gas in the opposite direction to the gas flow caused by the first fan. <10> The heating furnace described above. <12> The suction and ejection unit is characterized by periodically switching from a continuous suction and ejection mode, in which the first fan is driven and the first fan is not driven, to a backwash mode, in which the backwash fan is driven and the first fan is not driven, while operating in a continuous suction and ejection mode, in which the first fan is driven and the backwash fan is not driven. <11> The heating furnace described above. <13> The ratio of the operating time in the continuous suction and ejection mode to the total operating time in the backwash mode is 60% or more. <12> The heating furnace described above. <14> The bypass passage is provided with a check valve that, when open, allows gas to flow from the first extension to the second extension, but prevents gas from flowing from the second extension to the first extension. The check valve is characterized in that it is closed when the first fan is running and the backwash fan is not running during operation in continuous suction and ejection mode, and is open when the backwash fan is running and the first fan is not running during operation in backwash mode. <12> or <13> The heating furnace described above. <15> The cooler includes a first cooler positioned in the first extension section and a second cooler positioned in the second extension section, which is upstream of the backwashing fan when the backwashing fan is driven. In the continuous suction and ejection mode, the cooling function of the first cooler is on and the cooling function of the second cooler is off, and in the backwash mode, the cooling function of the first cooler is off and the cooling function of the second cooler is on, characterized in that the system is configured in this way. <12> ~ <14> A heating furnace as described in any one of the following. <16> The system is further characterized by comprising a rotation speed measurement unit that measures the rotation speed of the backwash fan during the continuous suction and ejection mode. <12> ~ <15> A heating furnace as described in any one of the following. <17> The suction nozzle unit includes a control unit for controlling the first fan. The control unit is characterized by controlling the drive of the first fan so that the rotational speed measured by the rotational speed measuring unit matches the reference rotational speed. <16> The heating furnace described above. <18> The heat exchanger is characterized in that it is positioned such that the dot product of the unit normal vector extending toward the side on which the workpiece is placed relative to the mounting surface on which the workpiece is placed, and the unit vector along the direction of travel of the gas ejected from the heat exchanger into the heat treatment space, is negative. <1> ~ <17> A heating furnace as described in any one of the following. <19> The suction and ejection sections are characterized by being provided in multiple locations. <1> ~ <18> A heating furnace as described in any one of the following. [Explanation of symbols]

[0121] 1. Object to be processed 10 Main body 11 Heat treatment space 12 Heating section 13 Drive rollers 14 Gas supply port 15 Gas outlet 20 Gas Supply Department 30 Suction spout part 31 Gas lines 31a First extension 31a1 First horizontal section 31a2 First vertical section 31b Second extension 31b1 Second horizontal section 31b2 Second vertical section 31c connection 32a First Fan 32b Second Fan 32c Backwash Fan 33a First condenser 33b Second condenser 34 Bypass channel 35 Control Unit 40 Heat exchanger 41 Suction path 42 Ejection channel 43 Bulkhead 50 Check valve 60 Rotational Speed ​​Measurement Unit 100, 100A, 100B, 100C, 100D, 100E Furnace F1 gas flow path F2 Refrigerant flow path

Claims

1. A main body having a heat treatment space for heat treatment of an object to be treated, and a heating unit disposed within the heat treatment space, A gas supply unit that supplies the gas necessary for heat treatment to the heat treatment space of the main body, A suction and ejection unit has a gas line connected to the heat treatment space of the main body, and continuously performs the suction of gas from the heat treatment space to the gas line and the ejection of the gas drawn into the gas line into the heat treatment space, A heat exchanger of the heat exchange type is provided inside the gas line for performing heat exchange between the gas drawn in from the heat treatment space and the gas ejected into the heat treatment space. Equipped with, The gas line is configured such that no gas is supplied from outside the heat treatment space. The heating furnace is characterized in that the heat exchanger is provided in a portion of the gas line that is located inside the main body.

2. The heating furnace according to claim 1, characterized in that the heat exchanger is provided in a region of the gas line that penetrates the main body.

3. The heat exchanger has a suction passage through which gas drawn in from the heat treatment space flows, and an outlet passage through which gas ejected into the heat treatment space flows. The heating furnace according to claim 1, characterized in that the gas line has a first extension connected to the suction passage of the heat exchanger, a second extension connected to the discharge passage of the heat exchanger, and a connecting portion connecting the first extension and the second extension.

4. The heating furnace according to claim 3, characterized in that a portion of the ejection passage is exposed within the heat treatment space of the main body.

5. The heating furnace according to claim 3, characterized in that the suction ejection section comprises a first fan arranged in the gas line.

6. The suction discharge unit is further equipped with a second fan positioned in the gas line and for directing the gas flow in the same direction as the gas flow caused by the first fan. The first fan is located in the first extension section, The heating furnace according to claim 5, characterized in that the second fan is located in the second extension portion.

7. The gas line is further provided with a cooler for cooling the gas that has been drawn in from the heat treatment space and passed through the heat exchanger, The heating furnace according to claim 5, characterized in that the cooler includes a first cooler positioned upstream of the first fan when the first fan is driven.

8. The heating furnace according to claim 7, characterized in that the cooler has a structure in which gas passages through which gas flows and refrigerant passages through which refrigerant flows are alternately stacked.

9. The gas line includes a portion that extends horizontally and a portion that extends vertically. The heating furnace according to claim 7, characterized in that the cooler is arranged in the portion of the first extension of the gas line that extends in the vertical direction.

10. The gas line is provided with a bypass channel, one end of which is connected to the horizontally extending portion of the first extension, connecting the first extension and the second extension. The heating furnace according to claim 9, wherein the suction ejection unit is arranged in the gas line and further comprises a backwashing fan for flowing gas in the opposite direction to the gas flow caused by the first fan.

11. The heating furnace according to claim 10, characterized in that the suction ejection unit periodically switches to a backwash mode in which the backwash fan is driven and the first fan is not driven while operating in a continuous suction ejection mode in which the first fan is driven and the backwash fan is not driven.

12. The heating furnace according to claim 11, characterized in that the ratio of the operating time in the continuous suction ejection mode to the total operating time in the backwash mode is 60% or more.

13. The bypass passage is provided with a check valve that, when open, allows gas to flow from the first extension to the second extension, but prevents gas from flowing from the second extension to the first extension. The heating furnace according to claim 11, characterized in that the check valve is closed during operation in the continuous suction ejection mode and open during operation in the backwash mode.

14. The cooler includes a first cooler positioned in the first extension section and a second cooler positioned in the second extension section at a location upstream of the backwashing fan when the backwashing fan is driven. The heating furnace according to claim 11, characterized in that in the continuous suction ejection mode, the cooling function of the first cooler is on and the cooling function of the second cooler is off, and in the backwash mode, the cooling function of the first cooler is off and the cooling function of the second cooler is on.

15. The heating furnace according to claim 11, further comprising a rotation speed measuring unit for measuring the rotation speed of the backwashing fan during the continuous suction ejection mode.

16. The suction nozzle includes a control unit for controlling the first fan, The heating furnace according to claim 15, characterized in that the control unit controls the drive of the first fan so that the rotational speed measured by the rotational speed measuring unit matches the reference rotational speed.

17. The heating furnace according to claim 1, characterized in that the heat exchanger is arranged such that the dot product of the unit normal vector extending toward the side on which the workpiece is placed with respect to the mounting surface on which the workpiece is placed, and the unit vector along the direction of travel of the gas ejected from the heat exchanger into the heat treatment space is negative.

18. The heating furnace according to any one of claims 1 to 17, characterized in that a plurality of suction ejection sections are provided.

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