heating furnace

Abstract

To actualize a longer cycle for switching between suction of gas from a heat treatment space of a body part to a gas line and jetting of gas from the gas line to the heat treatment space.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 repeating the suction of gas from the heat treatment space 11 to the gas line 31 and the 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] There is known a heating furnace that supplies gas into a furnace and performs heat treatment on an object to be processed.

[0003] As one such heating furnace, Patent Document 1 discloses a heating furnace that introduces the gas in the furnace into an external circulation path by a circulation fan and returns the gas introduced into the external circulation path back into the furnace again. In the external circulation path, a heat storage body for performing heat exchange with the gas and a flow path switching device are provided. By the flow path switching device, the flow of the gas flowing through the external circulation path is periodically switched, so that the gas introduced from the furnace into the external circulation path is heat-exchanged by the heat storage body and cooled, and the gas returned to the furnace is heat-exchanged by the heat storage body and heated before being ejected into the furnace. With such a configuration, it is said that the heating furnace described in Patent Document 1 can supply a strong circulation flow at a high temperature into the furnace.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

[0006] The present invention aims to solve the above problems and to provide a heating furnace that can extend the switching cycle 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. [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 having a gas line connected to the heat treatment space of the main body, which repeatedly draws gas from the heat treatment space into the gas line and ejects 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] According to the heating furnace of the present invention, the suction and ejection section is equipped with a heat exchanger, which makes it possible to lengthen the switching cycle between suction of gas from the heat treatment space to the gas line and ejection of gas from the gas line to the heat treatment space. That is, since the heat exchanger is configured to perform heat exchange between the high-temperature gas suctioned from the heat treatment space and the low-temperature gas ejected into the heat treatment space, it is possible to suppress the rapid temperature rise or fall that occurs in a heat storage body that repeatedly stores and releases heat, without switching the gas flow path. For this reason, it is possible to lengthen the switching cycle between suction of gas from the heat treatment space to the gas line and ejection of gas from the gas line to the heat treatment space. [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] (a) is a diagram illustrating the operation in the heating furnace of the first embodiment in which gas is drawn in from the heat treatment space to the first extension of the gas line and ejected through the second extension, and (b) is a diagram illustrating the operation in which gas is drawn in from the heat treatment space to the second extension of the gas line and ejected through the first extension. [Figure 6] This is a schematic cross-sectional view showing the configuration of the heating furnace in the second embodiment. [Figure 7] (a) is a diagram illustrating the operation in the heating furnace of the second embodiment in which gas is drawn into the first extension of the gas line and ejected through the second extension, and (b) is a diagram illustrating the operation in which gas is drawn into the second extension of the gas line and ejected through the first extension. [Figure 8] This is a schematic cross-sectional view showing the configuration of the heating furnace in the third embodiment. [Figure 9] This figure schematically shows the configuration of the heating furnace shown in Figure 8 when viewed from the direction of arrow Y1. [Figure 10] This is a schematic cross-sectional view showing the configuration of the heating furnace in the fourth embodiment. [Figure 11] 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 12] This is a schematic cross-sectional view showing the configuration of the heating furnace in the fifth embodiment. [Figure 13] A diagram showing the relationship between the rotational speed of a fan in a driving state and the rotational speed of a fan in a non-driving state, where (a) shows the rotational speed when the duty ratio is 60% when driving the fan by PWM control, and (b) shows the rotational speed when the duty ratio is 70%. [Figure 14] A cross-sectional view schematically showing the configuration of a heating furnace in the sixth embodiment. [Figure 15] A diagram showing the rotational speed and the like when controlling the driving of a fan in a driving state so that the rotational speed measured by a rotational speed measuring unit matches a reference rotational speed by a control unit. [Figure 16] A cross-sectional view schematically showing the configuration of a heating furnace in the seventh embodiment.

Mode for Carrying Out the Invention

[0010] Embodiments of the present invention are shown below, and the features of the present invention will be specifically described.

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

[0012] Here, the heating furnace 100 will be described as a roller hearth furnace. A roller hearth furnace is a continuous heating furnace in which a plurality of driving rollers 13 are arranged at regular intervals along the traveling direction in the furnace, and the workpiece 1 is conveyed on the driving rollers 13. FIG. 1 shows a cross-section when the heating furnace 100 is cut along a plane orthogonal to the conveying direction of the workpiece 1. However, the heating furnace 100 is not limited to a roller hearth furnace, and other types of heating furnaces such as a batch-type heating furnace may be used.

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

[0014] The main body 10 has a heat treatment space 11 for heat treatment of the workpiece 1, and includes a heating unit 12 located within 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 this embodiment, a drive roller 13 is arranged in the heat treatment space 11, and the heating unit 12 is positioned on the opposite side of the workpiece 1 from the drive roller 13, i.e., above the workpiece 1, so that the workpiece 1 is positioned between the drive roller 13 and the heating unit 12. However, the location of the heating unit 12 is not limited to the position on the opposite side of the workpiece 1 from the drive 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 treatment space 11 of the main body 10, and repeatedly draws gas from the heat treatment space 11 into the gas line 31 and ejects the gas drawn into the gas line 31 into the heat treatment space 11. In this specification, "repeatedly draws gas from the heat treatment space 11 into the gas line 31 and ejects the gas drawn into the gas line 31 into the heat treatment space 11" means that, as will be described later, the flow of gas drawn into the gas line 31 and the flow of gas ejected from the gas line 31 are alternately switched as the gas drawing and ejection are performed.

[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 first heat exchange channel 41 of the heat exchanger 40, which will be described later, a second extension 31b connected to the second heat exchange channel 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 at the first extension 31a of the gas line 31, and a second fan 32b located at the second extension 31b, which flows gas in the opposite direction to the gas flow caused by the first fan 32a. 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 will be collectively referred to as fan 32. Although not shown in the figures, the suction discharge unit 30 also includes a control unit for controlling the driving of the first fan 32a and the second fan 32b.

[0024] 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 not 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.

[0025] The second fan 32b is positioned so that when driven, gas flows from the second extension 31b of the gas line 31 to the connection 31c. That is, when the second fan 32b is driven, gas is drawn from the heat treatment space 11 to the second extension 31b of the gas line 31 via the heat exchanger 40. At this time, the first fan 32a is not driven. The gas drawn from the heat treatment space 11 to the second extension 31b of the gas line 31 passes through the connection 31c and the first extension 31a, and is ejected back into the heat treatment space 11 via the heat exchanger 40.

[0026] Alternatively, the first fan 32a may be positioned so that when it is driven, gas flows from the first extension 31a of the gas line 31 to the heat treatment space 11, and the second fan 32b may be positioned so that when it is driven, gas flows from the second extension 31b of the gas line 31 to the heat treatment space 11. In this case, when the first fan 32a is driven, gas is drawn from the heat treatment space 11 to the second extension 31b of the gas line 31 via the heat exchanger 40, and then ejected into the heat treatment space 11 via the first extension 31a and the heat exchanger 40. When the second fan 32b 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, and then ejected into the heat treatment space 11 via the second extension 31b and the heat exchanger 40.

[0027] The heating furnace 100 in this embodiment 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 and a second cooler 33b located in the second extension 31b of the gas line 31. The first cooler 33a is located in the first extension 31a at a position upstream of the first fan 32a when the first fan 32a is driven. The second cooler 33b is located in the second extension 31b at a position upstream of the second fan 32b when the second fan 32b is driven. Note that "upstream of the first fan 32a" means the upstream side 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. Similarly, "upstream of the second fan 32b" means the upstream side in the direction in which the gas flows when the second fan 32b is driven, and in Figure 2, this is the position closer to the heat exchanger 40 relative to the second fan 32b.

[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] The second cooler 33b is drawn from the heat treatment space 11 to the second extension 31b of the gas line 31 and cools the gas that has passed through the heat exchanger 40. For example, the gas drawn from the heat treatment space 11 to the second extension 31b of the gas line 31 is cooled to about 100°C by the heat exchanger 40. The gas cooled by the heat exchanger 40 is further cooled to below 50°C by the second cooler 33b. This prevents high-temperature gas from flowing into the second fan 32b and causing thermal damage.

[0030] Furthermore, the provision of the first cooler 33a and the second cooler 33b allows the temperature distribution of the heat exchanger 40 to be maintained in equilibrium. In other words, if the first cooler 33a and the second cooler 33b are not provided, the temperature of the heat exchanger 40 will rise during the process of repeatedly drawing gas from the heat treatment space 11 to the gas line 31 and ejecting gas 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.

[0031] However, in the heating furnace 100 of this embodiment, a first cooler 33a and a second cooler 33b are 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.

[0032] As will be described later, the first cooler 33a and the second cooler 33b are configured such that the cooling function of the cooler 32 located in the extension section that serves as the gas suction passage of the first extension section 31a and the second extension section 31b of the gas line 31 is turned on, and the cooling function of the cooler 32 located in the extension section that serves as the gas ejection passage is turned off.

[0033] For example, known heat exchangers can be used as the first cooler 33a and the second cooler 33b. Figure 3 is a schematic perspective view showing the configuration of a cooler 33 (first cooler 33a, second cooler 33b) 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.

[0034] 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.

[0035] 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.

[0036] 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. The same applies to the second cooler 33b.

[0037] Furthermore, the first cooler 33a and the second cooler 33b can be any type capable of cooling the gas, and are not limited to heat exchangers 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.

[0038] The heat exchanger 40 is a heat exchange type heat exchanger installed inside the gas line 31 for exchanging heat between the gas drawn in from the heat treatment space 11 and the gas ejected into the heat treatment space 11. The heat exchanger 40 has a first heat exchange channel 41 through which one of the gases, the gas drawn in from the heat treatment space 11 or the gas ejected into the heat treatment space 11, flows, and a second heat exchange channel 42 through which the other gas flows.

[0039] 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 first heat exchange channels 41 and second heat exchange channels 42 are alternately stacked. The first heat exchange channels 41 and second heat exchange channels 42 are configured to be parallel to each other. Although Figure 4 shows a configuration in which two layers each of the first heat exchange channels 41 and second heat exchange channels 42 are provided, the number of layers of the first heat exchange channels 41 and second heat exchange channels 42 is not limited to two.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] The first heat exchange channel 41 of the heat exchanger 40 is connected to the first extension 31a of the gas line 31, and the second heat exchange channel 42 is connected to the second extension 31b of the gas line 31. The heat exchanger 40 is provided with a plurality of first heat exchange channels 41 arranged in layers, and all of the first heat exchange channels 41 are connected to the first extension 31a. In addition, the heat exchanger 40 is provided with a plurality of second heat exchange channels 42 arranged in layers, and all of the second heat exchange channels 42 are connected to the second extension 31b.

[0044] As shown in Figure 4, a portion of the partition wall 43 separating the first heat exchange channel 41 and the second heat exchange channel 42 of the heat exchanger 40 is exposed within the heat treatment space 11 of the main body 10. 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. In Figure 4, the gas flow when gas is ejected from the first heat exchange channel 41 of the heat exchanger 40 to the heat treatment space 11 and when gas is drawn in from the heat treatment space 11 to the second heat exchange channel 42 is indicated by arrows.

[0045] In other words, in a configuration where a portion of the partition wall 43 is not exposed into the heat treatment space 11, the gas ejected 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 the gas to travel in a straight line. For example, when gas is ejected from the first heat exchange channel 41 of the heat exchanger 40 into the heat treatment space 11 and the gas is drawn in from the heat treatment space 11 into the second heat exchange channel 42, a flow is created in which a portion of the gas ejected from the first heat exchange channel 41 is immediately drawn into the second heat exchange channel 42.

[0046] However, as shown in Figure 4, a portion of the partition wall 43 separating the first heat exchange channel 41 and the second heat exchange channel 42 is exposed into the heat treatment space 11 of the main body 10. As a result, gas is drawn into the second heat exchange channel 42 not only in the straight-line direction but also from the side of the partition wall 43 exposed into the heat treatment space 11. This suppresses the flow of some of the gas ejected from the first heat exchange channel 41 into the second heat exchange channel 42, making it easier for the gas ejected into the heat treatment space 11 to travel in a straight line. The same applies when gas is drawn into the first heat exchange channel 41 and ejected from the second heat exchange channel 42.

[0047] The inventors conducted simulations and found that if the length L1 of the portion of the partition wall 43 exposed into the heat treatment space 11 is 1 / 2 or more of the widthwise dimension W1 of the heat exchanger 40, the interference between the ejected 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 partition wall 43 exposed into the heat treatment space 11 be 15 mm or more.

[0048] Furthermore, because a portion of the partition wall 43 is exposed into the heat treatment space 11, heat exchange with the gas ejected into the heat treatment space 11 is promoted in the region of the partition wall 43 that is exposed into 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.

[0049] Here, assuming the width dimension W1 of the heat exchanger 40 is 30 mm, the height H1 of the first heat exchange channel 41 and the second heat exchange channel 42 is 1.5 mm, the thickness D1 of the partition wall 43 is 1 mm, the length L1 of the portion of the partition wall 43 exposed into the heat treatment space 11 is 15 mm, the length L2 of the first heat exchange channel 41 and the second heat exchange channel 42 is 200 mm, the first heat exchange channel 41 and the second heat exchange channel 42 each have 7 layers, and the temperature of the heat treatment space 11 is 1200°C, the temperature of the gas ejected 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 heat exchanger 40 to the first extension 31a or the second extension 31b of the gas line 31 were confirmed. Here, the gas temperature was confirmed by changing the airflow rate of the gas flowing through the gas line 31 to 15 L / min, 30 L / min, and 45 L / min. The results of the verification 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.

[0050] [Table 1]

[0051] 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 discharged from the heat exchanger 40 to the first extension 31a or the second extension 31b 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 discharged from the heat exchanger 40 to the first extension 31a or the second extension 31b 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 discharged from the heat exchanger 40 to the first extension section 31a or the second extension section 31b of the gas line 31 was 138°C.

[0052] 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.

[0053] 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, passing through the heat exchanger 40, and being discharged will be 110°C or less. In this case, it becomes easy for the cooler 33 to lower the gas temperature to 60°C or less, which is the heat resistance temperature of the fan 32.

[0054] 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.

[0055] 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.

[0056] As shown in Figure 5(a), when the first fan 32a is driven and the second fan 32b is dedriven, the gas in the heat treatment space 11 of the main body 10 is drawn into the first heat exchange channel 41 of the heat exchanger 40. The temperature of the gas in the heat treatment space 11 is assumed to be, for example, about 1200°C.

[0057] At this time, the cooling function of the first cooler 33a located in the first extension section 31a, which serves as the gas suction passage, is turned on, and the cooling function of the second cooler 33b located in the second extension section 31b, which serves as the gas ejection passage, is turned off.

[0058] The gas drawn into the first heat exchange channel 41 of the heat exchanger 40 undergoes heat exchange with the gas flowing through the second heat exchange channel 42, and its temperature drops to around 100°C. The gas that has passed through the first heat exchange channel 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 channel 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 second heat exchange channel 42 of the heat exchanger 40. At this time, the cooling function of the second cooler 33b is turned off, so it is possible to prevent the gas introduced into the second heat exchange channel 42 from being cooled more than necessary.

[0059] The gas introduced into the second heat exchange channel 42 of the heat exchanger 40 undergoes heat exchange with the gas flowing through the first heat exchange channel 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 second heat exchange channel 42 is ejected into the heat treatment space 11 and reaches the surface of the multiple workpieces 1 on the plate 2.

[0060] In Figure 5(a), the direction of gas flow is indicated by arrows when gas is drawn from the heat treatment space 11 into the first heat exchange channel 41 of the heat exchanger 40, passes through the first extension 31a, connection 31c, and second extension 31b of the gas line 31, and then ejected from the second heat exchange channel 42 of the heat exchanger 40 into the heat treatment space 11.

[0061] Next, as shown in Figure 5(b), when the second fan 32b is driven and the first fan 32a is deactivated, the gas in the heat treatment space 11 of the main body 10 is drawn into the second heat exchange channel 42 of the heat exchanger 40. At this time, the cooling function of the second cooler 33b located in the second extension 31b, which is the gas suction channel, is turned on, and the cooling function of the first cooler 33a located in the first extension 31a, which is the gas ejection channel, is turned off. The gas drawn into the second heat exchange channel 42 of the heat exchanger 40 undergoes heat exchange with the gas flowing through the first heat exchange channel 41, and its temperature drops to around 100°C.

[0062] The gas that has passed through the second heat exchange channel 42 of the heat exchanger 40 is introduced into the second extension section 31b of the gas line 31 and is cooled to a temperature of 50°C or lower by passing through the gas channel F1 of the second cooler 33b. The gas that has passed through the second cooler 33b flows into the first extension section 31a through the connection section 31c of the gas line 31 and is introduced into the first heat exchange channel 41 of the heat exchanger 40. At this time, the cooling function of the first cooler 33a is turned off, so it is possible to prevent the gas introduced into the first heat exchange channel 41 from being cooled more than necessary.

[0063] The gas introduced into the first heat exchange channel 41 of the heat exchanger 40 undergoes heat exchange with the gas flowing through the second heat exchange channel 42, 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 first heat exchange channel 41 is ejected into the heat treatment space 11 and reaches the surface of the multiple workpieces 1 on the plate 2.

[0064] In Figure 5(b), the direction of gas flow is indicated by arrows when gas is drawn from the heat treatment space 11 to the second heat exchange channel 42 of the heat exchanger 40, passes through the second extension 31b, connection 31c, and first extension 31a of the gas line 31, and then ejected from the first heat exchange channel 41 of the heat exchanger 40 back to the heat treatment space 11.

[0065] Here, the operation of suction and ejection of gas by driving the first fan 32a and the operation of suction and ejection of gas by driving the second fan 32b are each defined as "1 cycle".

[0066] By repeating the above-described cycle, that is, driving the first fan 32a and driving the second fan 32b at regular intervals, the heat exchanger 40 can repeatedly perform the operation of drawing gas from the heat treatment space 11 through one of the first heat exchange flow paths 41 and the second heat exchange flow paths 42 and ejecting the gas into the heat treatment space 11 through the other flow path, and the operation of drawing gas from the heat treatment space 11 through the other flow path and ejecting the gas into the heat treatment space 11 through the first flow path.

[0067] In this embodiment, the heating furnace 100 is equipped with a heat exchanger 40, which makes it possible to extend the switching cycle described above. Specifically, since the heat exchanger 40 is configured to exchange heat between high-temperature gas drawn in from the heat treatment space 11 and low-temperature gas ejected into the heat treatment space 11, it is possible to suppress the rapid temperature rise or fall that occurs in a heat storage body that repeatedly stores and releases heat, without switching the gas flow path. For this reason, it is possible to extend the switching cycle between drawing gas from the heat treatment space 11 to the gas line 31 and ejecting gas from the gas line 31 to the heat treatment space 11.

[0068] In the heating furnace 100 of this embodiment, for reasons to be described later, the suction nozzle 30 switches between suctioning gas from the heat treatment space 11 to the first extension portion 31a of the gas line 31 and suctioning gas from the heat treatment space 11 to the second extension portion 31b of the gas line 31 at intervals of 10 seconds to 10 minutes.

[0069] The ratio of the operating time of the first fan 32a to the operating time of the second fan 32b is 1:1. However, the above ratio of operating times can be adjusted, for example, within the range of 0.4:0.6 to 0.6:0.4. In other words, the operating times of the first fan 32a and the second fan 32b can each be adjusted to a ratio of 40% to 60% of the total operating time for gas suction and ejection.

[0070] In this embodiment, the heating furnace 100 is equipped with a heat exchanger 40 for exchanging heat between the gas drawn in from the heat treatment space 11 and the gas ejected into the heat treatment space 11. Therefore, from the viewpoint of heat exchange characteristics, there is no need to switch the gas flow in the first heat exchange channel 41 and the second heat exchange channel 42 of the heat exchanger 40, and continuous operation is possible. However, if the gas flow is not switched, the gas is cooled by the cooler 33, which has its cooling function turned on, causing water vapor contained in the gas to condense, and increasing the amount of condensed water adhering to the surface.

[0071] Therefore, in the heating furnace 100 of this embodiment, the flow of gas drawn in from the heat treatment space 11 to the gas line 31 and the flow of gas ejected from the gas line 31 to the heat treatment space 11 are switched by the suction and ejection unit 30. This switching of gas flow can be done according to the condensation occurrence in the cooler 33. Therefore, the switching between driving the first fan 32a and driving the second fan 32b can be done at long intervals of 10 seconds to 10 minutes. As a result, the lifespan of the first fan 32a and the second fan 32b can be extended compared to a configuration in which the above switching is done at short intervals.

[0072] 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.

[0073] 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.

[0074] In the heating furnace 100 of this embodiment, the suction and ejection unit 30 repeatedly draws gas from the heat treatment space 11 into the gas line 31 and ejects the gas drawn into the gas line 31 into the heat treatment space 11. This allows a sufficient flow rate of gas to be supplied 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.

[0075] <Second Embodiment> Figure 6 is a schematic cross-sectional view showing the configuration of the heating furnace 100A in the second embodiment. The cutting position in the cross-sectional view shown in Figure 6 is the same as the cutting position in the cross-sectional view shown in Figure 2. The heating furnace 100A in the second embodiment differs from the heating furnace 100 in the first embodiment in the configuration of the suction nozzle 30.

[0076] In the heating furnace 100A of the second embodiment, the suction nozzle 30 further includes a third fan 32c and a fourth fan 32d compared to the configuration of the suction nozzle 30 of the first embodiment. The third fan 32c and the fourth fan 32d may have any structure as long as they are capable of blowing air, similar to the first fan 32a and the second fan 32b.

[0077] The third fan 32c is positioned at the first extension 31a of the gas line 31 and is a fan that directs the gas flow in the opposite direction to the gas flow caused by the operation of the first fan 32a. As described above, the first fan 32a is positioned so that when it is driven, the gas flows from the first extension 31a to the connection 31c, so the third fan 32c is positioned so that when it is driven, the gas flows from the connection 31c to the first extension 31a.

[0078] In this embodiment, the first fan 32a and the third fan 32c are arranged such that the gas driven by one fan flows toward the other fan. As described above, the first fan 32a is arranged so that when driven, the gas flows from the first extension portion 31a to the connection portion 31c. Therefore, the third fan 32c is located on the first extension portion 31a of the gas line 31, on the opposite side of the first fan 32a from the first cooler 33a. With this arrangement, the gas driven by the first fan 32a flows toward the third fan 32c, and the gas driven by the third fan 32c flows toward the first fan 32a.

[0079] The fourth fan 32d is located at the second extension 31b of the gas line 31 and is a fan that directs the gas flow in the opposite direction to the gas flow caused by the second fan 32b. As described above, the second fan 32b is positioned so that when it is driven, the gas flows from the second extension 31b to the connection 31c, so the fourth fan 32d is positioned so that when it is driven, the gas flows from the connection 31c to the second extension 31b.

[0080] In this embodiment, the second fan 32b and the fourth fan 32d are arranged such that the gas driven by one fan flows toward the other fan. As described above, the second fan 32b is arranged so that when driven, the gas flows from the second extension portion 31b to the connection portion 31c. Therefore, the fourth fan 32d is located on the second extension portion 31b of the gas line 31, on the opposite side of the second fan 32b from the second cooler 33b. With this arrangement, the gas driven by the second fan 32b flows toward the fourth fan 32d, and the gas driven by the fourth fan 32d flows toward the second fan 32b.

[0081] In this way, by providing two fans with opposite gas flow directions at the first extension 31a and the second extension 31b of the gas line 31, it becomes possible to distribute the pressure loss load caused by the operation of the fans to the two fans. This makes it possible to miniaturize the fan 32 installed in the gas line 31.

[0082] Here, the gas suction and ejection operations via the gas line 31 of the heating furnace 100A in the second embodiment will be described. When the gas in the heat treatment space 11 of the main body 10 is suctioned into the first heat exchange passage 41 of the heat exchanger 40, as shown in Figure 7(a), the first fan 32a and the fourth fan 32d are driven, and the second fan 32b and the third fan 32c are deactivated. At this time, the cooling function of the first cooler 33a located in the first extension 31a, which is the gas suction passage, is turned on, and the cooling function of the second cooler 33b located in the second extension 31b, which is the gas ejection passage, is turned off.

[0083] Conversely, when drawing gas from the heat treatment space 11 of the main body 10 into the second heat exchange passage 42 of the heat exchanger 40, as shown in Figure 7(b), the second fan 32b and the third fan 32c are driven, and the first fan 32a and the fourth fan 32d are deactivated. At this time, the cooling function of the first cooler 33a located in the first extension 31a, which is the gas ejection passage, is turned off, and the cooling function of the second cooler 33b located in the second extension 31b, which is the gas suction passage, is turned on.

[0084] Here, it is also possible to reverse the arrangement of the first fan 32a and the third fan 32c. However, the inventor's experiments have shown that in such an arrangement, the pressure loss generated by the non-driven fan 32 becomes large. Therefore, as in this embodiment, it is preferable that the gas generated by the driving of one of the fans, the first fan 32a and the third fan 32c, is directed toward the other fan.

[0085] Similarly, it is possible to reverse the arrangement of the second fan 32b and the fourth fan 32d, but in order to reduce pressure loss, it is preferable, as in this embodiment, that the gas driven by one of the second fan 32b and the fourth fan 32d is directed toward the other fan.

[0086] <Third Embodiment> In the heating furnace 100 in the first embodiment and the heating furnace 100A in the second embodiment, the gas line 31 is composed of a first extension portion 31a, a second extension portion 31b, and a connecting portion 31c, which are portions that extend in the horizontal direction.

[0087] In contrast, in the heating furnace 100B of the third embodiment, the gas line 31 includes a portion that extends horizontally and a portion that extends vertically.

[0088] In this description, similar to the heating furnace 100A in the second embodiment, the suction outlet 30 is described as having not only the first fan 32a and the second fan 32b, but also the third fan 32c and the fourth fan 32d. However, a configuration in which the third fan 32c and the fourth fan 32d are omitted is also possible.

[0089] Figure 8 is a schematic cross-sectional view showing the configuration of the heating furnace 100B in the third embodiment. Similar to Figure 1, Figure 8 shows a cross-section of the heating furnace 100B when cut by a plane perpendicular to the conveying direction of the workpiece 1. Figure 9 is a schematic diagram showing the configuration of the heating furnace 100B shown in Figure 8 when viewed from the direction of arrow Y1.

[0090] The gas line 31 in this embodiment has a shape obtained by bending the gas line 31 shown in Figure 6 upward at a point midway between the first extension portion 31a and the second extension portion 31b. That is, the gas line 31 in this embodiment also includes the first extension portion 31a, the second extension portion 31b, and the connecting portion 31c, but the shapes of the first extension portion 31a and the second extension portion 31b are different from those of the gas line 31 shown in Figure 6.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] As shown in Figure 9, the first cooler 33a, the first fan 32a, and the third fan 32c are positioned in the first vertical section 31a2, which is the vertically extending portion of the first extension section 31a of the gas line 31. The relative arrangement of the first cooler 33a, the first fan 32a, and the third fan 32c is the same as that of the heating furnace 100A in the second embodiment.

[0095] The gas drawn from the heat treatment space 11 and flowing into the first extension portion 31a of the gas line 31 is cooled by the first cooler 33a, which has its cooling function turned on. If the temperature of the gas after cooling falls below the dew point, the water vapor contained in the gas condenses and adheres to the surface. In the heating furnace 100B of this embodiment, the first cooler 33a is located in the first vertical portion 31a2 of the gas line 31, so that the condensed water adhering to the surface of the first cooler 33a can be allowed to fall off. This prevents the condensed water from remaining adhering to the surface of the first cooler 33a.

[0096] As shown in Figure 9, the second cooler 33b, the second fan 32b, and the fourth fan 32d are located in the second vertical section 31b2, which is the vertically extending portion of the second extension section 31b of the gas line 31. The relative arrangement of the second cooler 33b, the second fan 32b, and the fourth fan 32d is the same as that of the heating furnace 100A in the second embodiment.

[0097] The gas drawn from the heat treatment space 11 and flowing into the second extension 31b of the gas line 31 is cooled by the second cooler 33b, which has its cooling function turned on. If the temperature of the gas after cooling falls below the dew point, the water vapor contained in the gas condenses and adheres to the surface. In the heating furnace 100B of this embodiment, the second cooler 33b is located in the second vertical section 31b2 of the gas line 31, so that the condensed water adhering to the surface of the second cooler 33b can be allowed to fall off. This prevents the condensed water from remaining adhering to the surface of the second cooler 33b.

[0098] In this embodiment, the heating furnace 100B is located inside the gas line 31, vertically below the cooler 33, and further comprises a vaporizer 34 for vaporizing water. The vaporizer 34 is a heat sink with fins, made of a metal such as aluminum, iron, or copper, or of ceramic. The surface of the heat sink may be porous. However, the vaporizer 34 is not limited to a heat sink and can be anything that can vaporize water. In this embodiment, the vaporizer 34 includes a first vaporizer 34a and a second vaporizer 34b.

[0099] The first vaporizer 34a is located inside the gas line 31, vertically below the first cooler 33a, in the portion where the first horizontal section 31a1 and the first vertical section 31a2 are connected. The first vaporizer 34a is positioned to vaporize the condensation water that forms on the surface of the first cooler 33a and subsequently falls.

[0100] The second vaporizer 34b is located inside the gas line 31, vertically below the second cooler 33b, in the portion where the second horizontal section 31b1 and the second vertical section 31b2 are connected. The second vaporizer 34b is positioned to vaporize the condensation water that forms on the surface of the second cooler 33b and subsequently falls.

[0101] When the fan 32 controls the intake and discharge of gas at predetermined intervals, the condensed water moves to the higher temperature side of the cooler 33 or falls downwards, carried by the switched gas flow. The condensed water that falls downwards comes into contact with the vaporizer 34, vaporizes, and flows back into the heat treatment space 11 of the main body 10 as water vapor.

[0102] Thus, according to the heating furnace 100B in the third embodiment, the gas line 31 includes a portion that extends horizontally and a portion that extends vertically, and the cooler 33 is located in the portion that extends vertically, so that condensation water generated on the surface of the cooler 33 can be dropped off. This prevents condensation water from remaining attached to the surface of the cooler 33. In addition, because the cooler 33 is located in the portion that extends vertically of the gas line 31, it is possible to reduce the occupied area of ​​the equipment.

[0103] Furthermore, in the third embodiment, the heating furnace 100B is located vertically below the cooler 33 inside the gas line 31 and is equipped with a vaporizer 34 for vaporizing water, so that condensation water that falls from the surface of the cooler 33 can be quickly vaporized. As a result, the condensation water can be quickly recirculated into the heat treatment space 11 without accumulating inside the gas line 31, and the discrepancy between the composition of the gas ejected from the gas line 31 into the heat treatment space 11 and the composition of the gas inside the heat treatment space 11 can be reduced.

[0104] Furthermore, if the condensation that forms on the surface of the cooler 33 and drips down vaporizes inside the gas line 31, the vaporizer 34 can be omitted.

[0105] Furthermore, 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°.

[0106] <Fourth 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.

[0107] 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.

[0108] Therefore, in the heating furnace 100C of the fourth embodiment, the heat exchanger 40 is located away from the drive unit of the drive roller 13.

[0109] Figure 10 is a schematic cross-sectional view showing the configuration of the heating furnace 100C in the fourth embodiment. Similar to Figure 1, Figure 10 shows a cross-section of the heating furnace 100C when it is cut by a plane perpendicular to the conveying direction of the workpiece 1.

[0110] 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.

[0111] 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 11.

[0112] Furthermore, since gas is ejected from the heat exchanger 40 along the direction in which the first heat exchange channel 41 and the second heat exchange channel 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 first heat exchange channel 41 and the second heat exchange channel 42 extend toward the tip.

[0113] Figure 11 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 first heat exchange channel 41 and the second heat exchange channel 42 of the heat exchanger 40 is adjusted so that the gas is ejected diagonally downward from the heat exchanger 40.

[0114] In the fourth embodiment, the heating furnace 100C 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.

[0115] <Fifth Embodiment> Figure 12 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 12 is the same as the cutting position in the cross-sectional view shown in Figure 2.

[0116] The heating furnace 100D in the fifth embodiment further includes a rotation speed measuring unit 50 compared to the configuration of the heating furnace 100 in the first embodiment. The rotation speed measuring unit 50 measures the rotation speed of the non-driven fan 32 when one of the first fan 32a and the second fan 32b is driven and the other is not driven.

[0117] In a configuration with a heat exchanger 40, the pressure loss in the gas line 31 is smaller compared to a configuration with a heat storage body for repeated heat storage and release. Therefore, a fan with relatively low static pressure characteristics can be used as the fan 32 placed in the gas line 31. When the fan 32 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 fan 32 when it is not driven using the rotational speed measurement unit 50, it is possible to determine the airflow rate of the gas flowing through the gas line 31.

[0118] Figures 13(a) and (b) show the relationship between the rotational speed of the fan 32 when it is running and the rotational speed of the fan 32 when it is not running. The fan 32 when it is running is one of the first fan 32a and the second fan 32b, and the fan 32 when it is not running is the other fan. Figure 13(a) shows the rotational speed when the duty cycle is set to 60% when the fan 32 is driven by PWM control, and Figure 13(b) shows the rotational speed when the duty cycle is set to 70%. In Figure 13, PCnt1 is the rotational speed of the first fan 32a, and PCnt2 is the rotational speed of the second fan 32b.

[0119] As shown in Figures 13(a) and (b), the rotational speed of the non-driven fan 32 changes in accordance with the increase or decrease in the rotational speed of the driven fan 32. The temperature of the gas flowing through the gas line 31 is approximately constant between 30°C and 50°C, and the rotational speed of the non-driven fan 32 measured by the rotational speed measurement unit 50 corresponds to the airflow rate of the gas flowing through the gas line 31.

[0120] If the temperature of the gas in the heat treatment space 11 is changed, the temperature distribution of the gas flowing through the first heat exchange channel 41 and the second heat exchange channel 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 fan 32 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 fan 32 in operation.

[0121] However, in the heating furnace 100D of this embodiment, the rotational speed of the non-operating fan 32 can be measured by the rotational speed measuring unit 50, thereby accurately determining the airflow rate of the gas flowing through the gas line 31. Furthermore, since the fan 32, which is provided to circulate gas through the gas line 31, can be used to determine the airflow rate of the gas flowing through the gas line 31, there is no need to provide a separate device for measuring the airflow rate. This simplifies the configuration of the heating furnace 100D that can determine the airflow rate of the gas flowing through the gas line 31.

[0122] In addition, it is also possible to provide a rotation speed measuring unit 50 to the heating furnace 100A in the second embodiment. In that case, when one set of fans 32, consisting of the first fan 32a and the fourth fan 32d, and the second fan 32b and the third fan 32c, is in an operating state and the other set is in an inactive state, the rotation speed measuring unit 50 measures the rotation speed of at least one of the inactive fan 32s. In this case as well, the amount of gas flowing through the gas line 31 can be accurately determined based on the rotation speed of the inactive fan 32 measured by the rotation speed measuring unit 50.

[0123] <Sixth Embodiment> 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. The heating furnace 100E in the sixth embodiment, like the heating furnace 100D in the fifth embodiment, is equipped with a rotation speed measuring unit 50 and is characterized by the control of the control unit 35, which will be described later.

[0124] As shown in Figure 14, 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 fans 32 in the driven state so that the rotational speed measured by the rotational speed measuring unit 50 matches a 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 50 with the reference rotational speed, for example, by feedback control. By the control unit 35 controlling the driving of the 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.

[0125] Figure 15 is a diagram showing the rotational speed, etc., when the control unit 35 controls the drive of the fan 32 in the driven state so that the rotational speed measured by the rotational speed measurement unit 50 matches the reference rotational speed. In Figure 15, PWM1 is the output signal of the PWM control for controlling the fan 32 in the driven state in the first control state, iPCnt1 is the rotational speed of the fan 32 in the driven state in the first control state, PWM2 is the output signal of the PWM control for controlling the fan 32 in the driven state in the second control state, and iPCnt2 is the rotational speed of the fan 32 in the driven state in the second control state. The first control state is when the first fan 32a is driven and the second fan 32b is not driven. The second control state is when the first fan 32a is not driven and the second fan 32b is driven.

[0126] In the first and second control states, the output of the PWM control of the driven fan 32 was controlled so that the rotational speed of the non-driven fan 32, as measured by the rotational speed measurement unit 50, was 800 rpm. As a result, as shown in Figure 15, the rotational speed of the non-driven fan 32 was controlled to remain almost constant at 800 rpm.

[0127] In the control example described above, the rotational speed of the non-driven fan 32 was controlled to 800 rpm. However, it is possible to control the rotational speed to any desired level as long as the airflow is greater than or equal to the airflow required for the non-driven fan 32 to rotate stably, and the duty cycle of the PWM control of the driven fan 32 is within 100%.

[0128] Furthermore, the same control can be performed even if the heating furnace 100A in the second embodiment is equipped with a rotation speed measurement unit 50. That is, the control unit 35 only needs to control the operation of the fan 32 in the driven state so that the rotation speed measured by the rotation speed measurement unit 50 matches the reference rotation speed.

[0129] <Seventh Embodiment> The heating furnaces 100 in the first embodiment to the heating furnaces 100E in the sixth embodiment each have one suction nozzle 30. In contrast, the heating furnace 100F in the seventh 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 of each workpiece 1.

[0130] Figure 16 is a schematic cross-sectional view showing the configuration of the heating furnace 100F in the seventh embodiment. The cutting position in the cross-sectional view shown in Figure 16 is the same as the cutting position in the cross-sectional view shown in Figure 2.

[0131] In the example shown in Figure 16, 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.

[0132] 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.

[0133] 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.

[0134] 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. For example, a piston may be placed in the gas line 31, and the draw in and ejection of gas may be performed by the reciprocating motion of a movable part inside the cylinder of the piston.

[0135] 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 having a gas line connected to the heat treatment space of the main body, which repeatedly draws gas from the heat treatment space into the gas line and ejects 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 provided in a region within the gas line that penetrates the main body. <2> The heating furnace described above. <4> The heat exchanger has a first heat exchange channel through which one of the gases drawn in from the heat treatment space and the gas ejected into the heat treatment space flows, and a second heat exchange channel through which the other gas flows. The gas line is characterized by having a first extension connected to the first heat exchange flow path of the heat exchanger, a second extension connected to the second heat exchange flow path 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 partition wall separating the first heat exchange channel and the second heat exchange channel of the heat exchanger is exposed within the heat treatment space. <4> The heating furnace described above. <6> The suction discharge unit is characterized by comprising a first fan located in the first extension section and a second fan located in the second extension section for flowing gas in the opposite direction to the gas flow caused by the first fan. <4> or <5> The heating furnace described above. <7> The suction discharge section is further characterized by comprising a third fan located in the first extension section for flowing gas in the opposite direction to the gas flow caused by the first fan, and a fourth fan located in the second extension section for flowing gas in the opposite direction to the gas flow caused by the second fan. <6> The heating furnace described above. <8> The first fan and the third fan are arranged such that the gas generated by the operation of one fan is directed toward the other fan. The second fan and the fourth fan are arranged such that the gas generated by the operation of one fan is directed toward the other fan. <7> The heating furnace described above. <9> 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 by including a first cooler positioned in the first extension portion at a location upstream of the first fan when the first fan is driven, and a second cooler positioned in the second extension portion at a location upstream of the second fan when the second fan is driven. <6> ~ <8> A heating furnace as described in any one of the following. <10> The first and second coolers are configured such that the cooling function of the cooler located in the extension section of the gas line that serves as a gas suction passage is turned on, while the cooling function of the cooler located in the extension section that serves as a gas ejection passage is turned off. <9> The heating furnace described above. <11> 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. <9> or <10> The heating furnace described above. <12> The gas line includes a portion extending horizontally and a portion extending vertically. The cooler is characterized by being positioned in the portion extending in the vertical direction. <9> ~ <11> A heating furnace as described in any one of the following. <13> The gas line is further characterized by comprising a vaporizer located vertically below the cooler within the gas line for vaporizing water. <12> The heating furnace described above. <14> The suction nozzle is characterized by switching between drawing gas from the heat treatment space to the first extension of the gas line and drawing gas from the heat treatment space to the second extension of the gas line at intervals of 10 seconds to 10 minutes. <4> ~ <13> A heating furnace as described in any one of the following. <15> The system is further characterized by comprising a rotation speed measuring unit that measures the rotation speed of the non-operating fan when one of the first fan and the second fan is in operation and the other is not. <6> , <9> , <10> , <11> , <12> or <13> The heating furnace described above. <16> The system further comprises a rotation speed measuring unit that measures the rotation speed of at least one of the non-driven fans when one of the sets of fans, the first and fourth fan set or the second and third fan set, is in an operating state and the other set is not in an operating state. <7> or <8> The heating furnace described above. <17> The suction and ejection unit includes a control unit for controlling the driving of the first fan and the second fan. The control unit is characterized by controlling the operation of the fan in the operating state so that the rotational speed measured by the rotational speed measuring unit matches the reference rotational speed. <15> or <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]

[0136] 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 The third fan 32d The 4th Fan 33a First condenser 33b Second condenser 34a First vaporizer 34b Second vaporizer 35 Control Unit 40 Heat exchanger 41 First heat exchange channel 42 Second heat exchange channel 43 Bulkhead 50 Rotational Speed ​​Measurement Unit 100, 100A, 100B, 100C, 100D, 100E, 100F 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 having a gas line connected to the heat treatment space of the main body, which repeatedly draws gas from the heat treatment space into the gas line and ejects 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 heating furnace according to claim 1, characterized in that the heat exchanger is provided in a portion of the gas line that is located inside the main body.

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

4. The heat exchanger has a first heat exchange channel through which one of the gases drawn in from the heat treatment space and the gas ejected into the heat treatment space flows, and a second heat exchange channel through which the other gas flows. The heating furnace according to claim 1, characterized in that the gas line has a first extension connected to the first heat exchange flow path of the heat exchanger, a second extension connected to the second heat exchange flow path of the heat exchanger, and a connecting portion connecting the first extension and the second extension.

5. The heating furnace according to claim 4, characterized in that a portion of the partition wall separating the first heat exchange channel and the second heat exchange channel of the heat exchanger is exposed into the heat treatment space.

6. The heating furnace according to claim 4, characterized in that the suction ejection section comprises a first fan located in the first extension section and a second fan located in the second extension section for flowing gas in the opposite direction to the gas flow caused by the first fan.

7. The heating furnace according to claim 6, further comprising a third fan located in the first extension section for directing gas flow in the opposite direction to the gas flow caused by the first fan, and a fourth fan located in the second extension section for directing gas flow in the opposite direction to the gas flow caused by the second fan.

8. The first fan and the third fan are arranged such that the gas generated by the operation of one fan is directed toward the other fan. The heating furnace according to claim 7, characterized in that the second fan and the fourth fan are arranged such that the gas driven by one fan is directed toward the other fan.

9. 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 6, characterized in that the cooler includes a first cooler positioned in the first extension portion at a location upstream of the first fan when the first fan is driven, and a second cooler positioned in the second extension portion at a location upstream of the second fan when the second fan is driven.

10. The heating furnace according to claim 9, wherein the first cooler and the second cooler are configured such that the cooling function of the cooler located in the extension portion that serves as a gas suction passage of the first extension portion and the second extension portion of the gas line is turned on, and the cooling function of the cooler located in the extension portion that serves as a gas ejection passage is turned off.

11. The heating furnace according to claim 9, 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.

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

13. The heating furnace according to claim 12, further comprising a vaporizer for vaporizing water, which is located vertically below the cooler inside the gas line.

14. The heating furnace according to claim 4, characterized in that the suction ejection unit switches between drawing gas from the heat treatment space to the first extension of the gas line and drawing gas from the heat treatment space to the second extension of the gas line at intervals of 10 seconds to 10 minutes.

15. The heating furnace according to claim 6, further comprising a rotation speed measuring unit for measuring the rotation speed of the non-driven fan when one of the first fan and the second fan is in a driven state and the other is not in a driven state.

16. The heating furnace according to claim 7, further comprising a rotation speed measuring unit that measures the rotation speed of at least one of the non-driven fans when one of the sets of the first and fourth fans and the second and third fans is in an operating state and the other set is not in an operating state.

17. The suction ejection unit includes a control unit for controlling the driving of the first fan and the second fan. The heating furnace according to claim 15, characterized in that the control unit controls the operation of the fan in operation so that the rotational speed measured by the rotational speed measuring unit matches the reference rotational speed.

18. 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.

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

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