Firing apparatus

Abstract

To provide a firing apparatus that prevents excessive increases in exterior and exhaust temperatures, and allows for comfortable use by people. [Solution] A firing apparatus comprising a furnace body 2 in which the workpiece to be fired is heated, a housing covering the periphery of the furnace body 2, a fan for discharging air between the furnace body 2 and the housing, an air intake port 8 provided on the upstream side of the airflow path formed by the fan for taking in outside air, and an exhaust port 9 provided on the downstream side of the airflow path for exhausting the outside air taken in from the air intake port 8, wherein at least one surface of the housing has an insulating area and a heat exchange area.

Description

Technical Field

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[0001] The present invention relates to a firing apparatus having a heating chamber.

Background Art

[0002] Conventionally, ceramic restorations have been used as dental restorations, but in recent years, zirconia, which is excellent in aesthetics, has been widely used. Since zirconia is hard, it was difficult to process, but with the development of processing technology in recent years, dental clinics have been able to process in-house by introducing a CAD / CAM system.

[0003] A zirconia restoration obtained by shaping a semi-sintered zirconia material with a CAD / CAM system is fired in a firing apparatus to develop strength.

[0004] However, since the inside of the firing apparatus for zirconia is heated to about 1600°C, measures such as attaching heat insulation material inside the housing so that people do not touch the outside of the firing apparatus and get burned, or creating an air flow inside the housing with a fan to cool the exterior are taken. However, in order to install the firing apparatus in a dental clinic, it is required to be small and not to overheat the exterior and exhaust.

[0005] For example, in the electric furnace shown in Patent Document 1, by driving a cooling fan device, the heated air around the heat insulation layer surrounding the heating chamber is dissipated to the outside of the housing through the ventilation layer outside the heat insulation layer, so that a good cooling function can be provided, and the electric furnace can be downsized and lightened.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In recent years, there has been a growing demand for miniaturization of firing equipment. One method used to achieve this is to thin the insulation material around the outside of the furnace body. However, thinning the insulation material increases the temperature around the outside of the furnace body. Consequently, it is necessary to suppress the temperature rise of the exterior. While applying insulation material to the entire inner surface of the side plates reduces the effect of radiant heat from the high-temperature heater unit, it presents the problem that the cooling air heated by the heater unit is not cooled, causing the exhaust and exhaust port to become hot. [Means for solving the problem]

[0008] In view of the above issues, the firing apparatus according to the present invention is The furnace body in which the object to be fired is heated, A housing that covers the periphery of the furnace body, A fan for exhausting air between the furnace body and the housing, An air intake port is provided on the upstream side of the airflow path formed by the aforementioned fan, which takes in outside air. An exhaust port is provided on the downstream side of the air passage and exhausts the outside air taken in from the intake port. It has, The housing is characterized in that at least one surface is provided with a heat insulating region and a heat exchange region in that order along the airflow. [Effects of the Invention]

[0009] This invention makes it possible to prevent the exhaust and exhaust port from becoming excessively hot, even when the firing apparatus is miniaturized. [Brief explanation of the drawing]

[0010] [Figure 1] Front side perspective view illustrating the firing apparatus in this embodiment. [Figure 2] Rear and internal perspective views illustrating the firing apparatus in this embodiment. [Figure 3] Rear perspective view illustrating the firing apparatus in this embodiment. [Figure 4] Top and side views of the firing apparatus in Example 1 [Figure 5] Top and side views of the firing apparatus in Example 2 [Figure 6] Top view and side view of the firing apparatus in Example 3 [Figure 7] Graph for explaining the effects of this embodiment

Mode for Carrying Out the Invention

[0011] The firing apparatus according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a front view of the firing apparatus, and FIG. 2 is a rear view. The firing apparatus 1 comprises a furnace body 2 incorporating a heater not shown, a housing covering the periphery of the furnace body 2 including a right side plate 3, a left side plate 4, a front panel 5, a rear panel 6, and a top plate 7, an intake port 8 for taking in outside air, an exhaust port 9 for discharging high-temperature air around the furnace body 2, an exhaust fan 9a provided at the exhaust port 9, a heat insulating material 10, a cable 12, a baffle plate 13 forming a flow path for cooling air, a thermocouple 19 for detecting the temperature inside the furnace, and an electrical equipment unit not shown built into the lower inside of the firing apparatus.

[0012] In addition, in this figure, in order to explain the internal structure, it is shown in the state where the rear panel 6 is removed in FIG. 2, but it is attached to the rear side of the firing apparatus during use.

[0013] The heater is supplied with power from the electrical equipment unit via the cable 12, and controls the temperature inside the furnace according to a predetermined temperature program while detecting the temperature inside the furnace by the thermocouple 19.

[0014] As the heater, a resistance heating element such as molybdenum disilicide, silicon carbide, or carbon is used. In particular, molybdenum disilicide heaters are often used for firing zirconia, which is a material often used in recent years as a material for dental restorations. The heater is usually formed into a rod shape and then bent into a U shape, a W shape, or a coil shape.

[0015] a> The object to be fired is fired inside the furnace body. As materials for dental restorations that require firing, lithium disilicate and zirconia are usually used. In the case of zirconia, it is fired at a temperature of 1500 to 1600 ° C for several tens of minutes to about 2 hours.

[0016] The furnace body 2 has a structure in which the heater is surrounded by a cylindrical heat-resistant insulating material. However, when firing is performed at about 1600°C for about 2 hours, the surface of the furnace body becomes about 100°C to 300°C. Therefore, due to heat conduction, convection, and radiation, not only the temperature inside the firing device but also the temperature of the exterior increases. When the temperature of the exterior increases, a person may feel hot when touching it. Therefore, cooling air is passed through the space between the furnace body 2 and the housing to lower the temperature of the exterior.

[0017] The way of flowing the cooling air varies depending on the structure of the firing device. In the firing device 1 of the present embodiment, as shown in FIG. 2, outside air is taken in from the intake port 8 on the upstream side of the air path formed on the back surface. The taken-in outside air passes through the outer periphery of the furnace body 2 and the exhaust fan 9a on the downstream side of the air path attached to the back surface also exhausts the internal air in the direction of the arrow.

[0018] The intake port 8 has a structure in which holes are made in the back plate 6 and is covered with punching metal so that a person cannot touch the inside. However, a net-like filter may be attached, or holes may be formed with slits or louvers of a width that does not allow a finger to enter the back plate.

[0019] In FIG. 2, the baffle plate 13 prevents the cooling air from flowing directly from the intake port 8 to the exhaust fan 9a and forms a flow path for the cooling air so that it passes through the front side of the outer periphery of the furnace body and is exhausted.

[0020] In the present embodiment, an insulating region and a heat exchange region 20 (see FIG. 4) are provided inside the left side plate 4 located on the downstream side of the cooling air path. The insulating material 10 is arranged in the insulating region, and the heat exchange region 20 exposes the sheet metal base of the left side plate 4.

[0021] In the insulating region, a part of the left side plate 4 is covered with the insulating material 10 centering on the portion closest to the furnace body 2, shielding the radiant heat to the left side plate 4 and preventing the temperature of the left side plate 4 from rising excessively.

[0022] The insulation material 10 only needs to be about the width of the furnace body at the position closest to the furnace body on the left side panel 4. If the entire left side panel 4 is covered, the air heated upstream of the air duct will be exhausted directly, meaning the exhaust temperature will be high. On the other hand, to lower the exhaust temperature, the cooling air flow rate can be increased, but driving the exhaust fan 9a at high speed to increase the exhaust volume will increase the noise of the exhaust fan 9a.

[0023] On the other hand, the heat exchange region 20 lacks insulation, and the exhaust temperature can be lowered by exchanging heat by bringing cooling air into contact with the bare surface of the left side panel 4. The heat energy exchanged here is diffused throughout the left side panel 4 by heat conduction, so the temperature of the left side panel 4 does not become locally high.

[0024] Furthermore, insulation material may be attached to part or all of the right side panel 3, front panel 5, back panel 6, and top panel 7.

[0025] Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

[0026] Figure 2 shows an embodiment of the present invention. The furnace body 2 is made of hollow cylindrical ceramic fiber and is equipped with a molybdenum disilicide heater (not shown) inside.

[0027] The enclosure, including the right side panel 3, left side panel 4, front panel 5, and rear panel 6, is made from 1mm thick stainless steel sheet, and the outer surface is painted to improve its appearance. The inside of the exterior is fitted with a blanket-shaped heat-resistant insulation material 10 to prevent the exterior from becoming hot due to radiant heat from the furnace body.

[0028] The insulation material 10 can be a blanket or board made of ceramic fiber or alumina fiber. It is sufficient if it has a heat resistance of 300°C or higher, and a thermal conductivity of 0.3 W / m·K or less is desirable, and 0.2 W / m·K or less is even more desirable. In this embodiment, a blanket-shaped ceramic fiber with a thickness of 10 mm was used, but the thickness is not limited to this and may be changed depending on the temperature of the furnace surface.

[0029] Figure 3 is a schematic diagram of a firing apparatus 1, an example of the present invention, viewed from the rear, and shows the intake and exhaust. The intake port 8 is a stainless steel perforated metal with many holes with a diameter of 5 mm. In this embodiment, the exhaust fan 9a rotates in a direction that expels air from inside the firing apparatus.

[0030] <Example 1> Next, a firing apparatus according to Example 1 of the present invention will be described.

[0031] The flow path of the cooling air 16 inside the firing apparatus, viewed from direction a in Figure 3, is shown in the diagram indicated by arrow a in Figure 4(a).

[0032] Furthermore, the positional relationship between the left side panel 4, the furnace body 2, and the insulation material 10 as viewed from direction b in Figure 1 is shown in the diagram indicated by arrow b in Figure 4(b). The insulation material 10 is positioned where the furnace body 2 is projected onto the left side panel 4, and it is desirable that it covers at least the area on the inner surface of the left side panel 4 that is closest to the furnace body 2. In other words, the insulation material 10 is positioned at least opposite the furnace body 2.

[0033] In Figure 4(b), the heat exchange region 20 indicated by the arrow is located on the exhaust fan 9a side of the insulation material 10, and no insulation material is placed there, leaving the bare surface of the inner surface of the left side panel 4 exposed. Here, heat is absorbed from the outer circumference of the heater, and the hot air is radiated onto the left side panel 4, lowering the temperature of the air. As a result, the exhaust gas discharged by the exhaust fan 9a can be discharged without becoming hot.

[0034] <Example 2> Next, a firing apparatus according to Embodiment 2 of the present invention will be described. The basic configuration of Embodiment 2 is the same as that of Embodiment 1. Therefore, in the following description, the same reference numerals will be used for the same parts, and their explanations will be omitted.

[0035] In Example 2, as shown in the diagram indicated by arrow a in Figure 5(a) viewed from direction b in Figure 1, a heat conductive member 11 is attached to the inner surface of the heat exchange region 21 of the left side panel 4 used in Example 1. The material of the heat conductive member 11 is preferably one with a thermal conductivity equal to or higher than that of the left side panel 4, and metals such as iron, stainless steel, copper, aluminum, brass, zinc, nickel, and alloys thereof can be used.

[0036] Furthermore, a large surface area is desirable, and materials made from the aforementioned material in the form of thin plates or with an uneven surface are preferred. In this embodiment, fins made by combining thin aluminum plates were used. The heat conduction member 11 was attached by screwing it in tightly to the inner surface of the heat exchange area 21 of the left side panel 4.

[0037] <Example 3> Next, a firing apparatus according to Embodiment 3 of the present invention will be described. The basic configuration of Embodiment 3 is the same as that of Embodiment 1. Therefore, in the following description, the same reference numerals will be used for the same parts, and their explanations will be omitted.

[0038] In Examples 1 and 2, the air intake 8 is formed in the back panel 6, but in this embodiment, as shown by arrow a in Figure 6(a) viewed from direction b in Figure 1, the air intake 8 is provided on the front panel side of the right side panel 3. In this configuration, the flow of cooling air 16 splits into two paths with the furnace body 2 in between, so heat exchange regions 20 and 22 without the heat insulation 10 are provided so that the sheet metal surface of the side panel is exposed on the inner surface downstream of the heat insulation 10, which is the downstream side of the air passage of the right side panel 3 and the left side panel 4, respectively.

[0039] <Measurement data for each example> In the above embodiments, Figure 7 shows the temperatures at positions A through D in the diagrams indicated by arrows b in Figures 4(b), 5(b), and 6(b). A through C are the outer surface temperatures of the left side panel 4, and D is the exhaust temperature from the exhaust fan 9a. Temperature measurements were taken in a general environment at room temperature of 23°C, and the firing conditions for the firing apparatus were room temperature → 1550°C / 160 minutes, followed by 1550°C anchoring for 120 minutes. When the exterior is made of metal, temperatures above 70°C are considered hot to the touch, so it is preferable to keep the exterior and exhaust temperatures below 70°C.

[0040] As a comparative example, Figure 7 shows the temperature when the insulation material 10 is installed to completely cover the left side panel 4. The temperature was kept below 70°C at positions A to C, but it exceeded 70°C at the exhaust (section D).

[0041] In Example 1, by providing a heat exchange region 20, the temperature at all locations from A to D is kept below 70°C.

[0042] In Example 2, the installation of the heat conduction member 11 increased the amount of heat exchange between the high-temperature cooling air and the left side panel 4, further reducing the temperature of the exhaust (section D) discharged by the exhaust fan 9a.

[0043] In Example 3, even when the air intake port 8 is located on the front panel side, it is possible to prevent the exhaust temperature from becoming high, and the temperature is kept below 70°C at all positions from A to D.

[0044] Based on the above, the effect of lowering the temperature of the exhaust gas (section D) was obtained in Examples 1 to 3.

[0045] The present invention is not limited to those described above, and various modifications can be applied without departing from the spirit of the invention. For example, in the above embodiment, only the case in which the exhaust port 9 is provided on the rear side has been described, but it may also be provided on the rear side of the left side panel 4. In that case as well, by providing a heat exchange region 20 at a position adjacent to the upstream side of the exhaust port 9 on the left side panel 4, it is possible to prevent the exhaust temperature from becoming too high. In this case, when the airflow generated by the exhaust fan 9a flows from the front side to the rear side of the housing, it comes into contact with the rear panel 6 before reaching the exhaust port 9. Therefore, it is preferable to provide the heat exchange region 20 on the left side panel 4 side (adjacent to the exhaust port 9) of the rear panel 6 of the housing, which is upstream of the airflow to the exhaust port 9.

[0046] Furthermore, regardless of the position of the exhaust port 9, a heat exchange region 20 and a heat conductive member 11 may be provided between the exhaust port 9 and the baffle plate 13.

[0047] Furthermore, when a heat conduction member 11 is provided, it is preferable that it is fixed to the housing at a position in the height direction of the housing that is spaced downward from the exhaust port 9, regardless of its position. In this case, when the heat transferred to the heat conduction member 11 escapes to the housing through the fixing part of the heat conduction member 11, the heat can escape to the housing at a position away from the exhaust port 9, thus preventing it from contributing to the temperature rise of the exhaust port 9. Moreover, if the workpiece heated in the furnace body 2 is lowered into a space provided below the furnace body 2 as shown in Figure 1 and cooled by a cooling fan (not shown), it is preferable that the fixing part of the heat conduction member 11 to the housing or the heat conduction member 11 itself be placed in the intake path of the cooling fan or the exhaust path of the cooled air. That is, although the workpiece is not cooled by the cooling fan during firing, the heat conduction member 11 can be cooled by driving the cooling fan, thereby effectively lowering the exhaust temperature.

[0048] In this configuration, unlike the above embodiment, the exhaust temperature can be reduced by actively exchanging heat with the heat conduction member 11 without adjusting the degree of heat insulation and heat exchange, thereby utilizing the heat capacity of the entire housing. Therefore, the heat conduction member 11 may be provided in a position that overlaps each of the heat insulation materials 10 and their interior sides in the housing. For example, the heat conduction member 11 may be positioned to extend to the right in Figure 5 so as to overlap with the heat insulation material 10 provided on the inner surface of the left side panel 4 in Figure 5. Furthermore, the heat conduction member 11 may be positioned so as to completely overlap the heat insulation material 10, and even in that case, the airflow will still be heat-exchanged by the heat conduction member 11 after passing through the heat insulation material 10 before being exhausted. [Explanation of Symbols]

[0049] 1. Firing apparatus 2 Furnace body 3 Right side plate 4 Left side plate 5 Front Panel 6 Back plate 7 Top plate 8 Air intake 9 Exhaust vents 9a Exhaust fan 10. Insulation 11 Heat conductive material 12 Cables 13 Baffle board 16 Cooling air 19 Thermocouples 20,21,22 Heat exchange area

Claims

1. The furnace body in which the object to be fired is heated, A housing that covers the periphery of the furnace body, A fan for exhausting air between the furnace body and the housing, An air intake port is provided on the upstream side of the airflow path formed by the aforementioned fan, which takes in outside air. An exhaust port is provided on the downstream side of the air passage and exhausts the outside air taken in from the intake port. It has, A firing apparatus characterized in that at least one surface of the housing is provided with an insulating region and a heat exchange region in that order along the airflow.

2. The firing apparatus according to claim 1, characterized in that the intake port and the exhaust port are located on the rear surface of the furnace body, outside air taken in from the intake port is exhausted from the exhaust port via the outer circumference of the furnace body, and the heat insulating region, the heat exchange region, and the exhaust port are arranged in that order from the upstream of the air passage to the downstream of the air passage.

3. The heat insulating region and the heat exchange region are located adjacent to the exhaust port, The firing apparatus according to claim 2, characterized in that the heat insulating region is positioned at least opposite to the furnace body.

4. The firing apparatus according to claims 1 to 3, characterized in that a heat conductive member is placed in the heat exchange region.

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