JP2019113215A - Heating furnace, and heating method - Google Patents

Abstract

To provide a heating furnace and a heating method for blowing heated air onto a member to be heated, capable of uniformly heating a member to be heated by controlling the difference of temperatures of air being blown out from a plurality of blowout ports.SOLUTION: A heating furnace 100 comprising a blower 20 that delivers air to a heating duct 30, a heater 40 that heats air in the heating duct 30, a distribution duct 50 that delivers air present in the heating duct 30, a plurality of branch ducts 60 that branch air from the distribution duct 50, a plurality of blowout ports 70 each blowing out air from the respective branch duct 60, and discharge ports 52a to 52e that discharge air from the distribution duct 50, disposed in a housing 10, is structured so that air of a lowered temperature lowered in the duct by its wall is discharged from the discharge ports 52a to 52e to decrease air of a lowered temperature present in the distribution duct 50 and only residual air is blown out from the blowout ports 70 and blown onto a member to be heated.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a heating furnace and a method for blowing heated air onto a member to be heated.

  In order to dry or cure an article, heated air is blown from a plurality of outlets to a member to be heated in a heating furnace to heat the member to be heated. Heating time is shorter when the heated air is blown to the heated member to heat the heated member than when the heated member is heated in the heated atmosphere.

Patent Document 1 discloses a drying apparatus which blows hot air from a plurality of outlets into a drying furnace to dry and cure a printed wiring board.
Patent Document 2 discloses a system for heating (drying) a member to be heated by high-pressure injection of hot air onto the member to be heated from a plurality of outlets inside a heating furnace.

Japanese Patent Application Laid-Open No. 6-55123 JP, 2009-92352, A

  In the case of heating the heated member by blowing heated air to the heated member from the plurality of outlets, if there is a temperature difference in the air sprayed from the respective outlets, it is possible to uniformly heat the heated member. Absent. Therefore, it is required to make the blown air have no temperature difference. However, due to various factors, it is difficult to remove the temperature difference of the air. Therefore, the amount of heat applied to the heated member varies depending on where the heated member is disposed in the heating furnace or the drying furnace, and uniform heating can not be performed.

  The drying device disclosed in Patent Document 1 blows hot air sent to a duct from a plurality of holes and blows it onto a printed wiring board. This is for the purpose of preventing the variation in the ambient temperature inside the drying furnace. However, no mention is made of a device for suppressing the temperature difference of the hot air blown from the respective holes and blown to the printed wiring board.

  Moreover, the heating furnace system disclosed by patent document 2 blows off the hot air sent to the blowing duct from several blowing nozzles, and blows on a to-be-heated member. In this system, there is no mention of the temperature difference of the hot air blown out from each blowout nozzle.

  However, in an actual heating furnace, there is a temperature difference between the hot air blown from the plurality of outlets. Therefore, it is difficult to heat the member to be heated uniformly.

  The present invention has been made in view of the above situation, and in order to uniformly heat a member to be heated, the temperature difference of the hot air blown out from a plurality of outlets and sprayed to the member to be heated is suppressed to be heated It aims at providing a method of heating a member, and a heating furnace using the method.

In order to achieve the above object, a heating furnace according to a first aspect of the present invention is
A heating furnace which blows heated air to a heated member to heat it, and
A first duct that is a flow path of air;
A blower for delivering air to the first duct;
A heater for heating the air in the first duct;
A plurality of second ducts connected to the first duct to branch heated air and having an outlet for blowing the heated air to the heated member;
A housing including the first duct, the blower, and the plurality of second ducts;
Have
The first duct has an outlet for discharging a part of the heated air into the housing at a position upstream of the connecting portion with the second duct and downstream of the heater. Prepare.

  Preferably, the discharge port has a lid covering the discharge port, and the opening area of the discharge port is adjusted by moving the position of the lid.

According to the second aspect of the present invention, there is provided a method of blowing heated air to a member to be heated and heating the same;
Inside a housing containing a first duct, a blower, and a plurality of second ducts,
Air is sent to the first duct by the blower;
The air in the first duct is heated by a heater,
Branching the heated air to the plurality of second ducts connected to the first duct;
A portion of the heated air is discharged into the housing from an outlet at a position downstream of the heater on the upstream side of the connecting portion with the second duct included in the first duct. ,
The heated air is blown to the member to be heated from the outlets of the plurality of second ducts.

  According to the present invention, since the hot air whose temperature difference is suppressed can be blown to the member to be heated from the plurality of outlets, the member to be heated can be uniformly heated.

1 is a front view of a heating furnace according to an embodiment of the present invention. 1 is a side view of a heating furnace according to an embodiment of the present invention. It is BB sectional drawing (refer FIG. 2) based on embodiment of this invention. It is AA sectional drawing (refer FIG. 1) based on embodiment of this invention. It is a perspective view showing the detail of the blowing duct concerning the embodiment of the present invention. It is a perspective view which shows the usage method based on embodiment of this invention. It is a perspective view which shows the use condition based on embodiment of this invention. It is a C section enlarged view (refer FIG. 7) based on embodiment of this invention. It is a perspective view showing the bottom of a heating furnace concerning an embodiment of the invention in this application. It is a perspective view showing the adjustment part of the discharge port concerning the modification of the present invention.

Before the embodiment of the present invention is described, a factor causing a temperature difference between the air blown out from the outlets when the heated air in the duct is blown out from the outlets will be described.
The heated air inside the duct flows inside the duct towards the outlet. In general, ducts often have bends for layout reasons. At the bent portion, the air flow is not uniform, and a stagnant portion is generated.
The temperature of the duct wall is lower than the heated air inside the duct. Therefore, the temperature of the portion of the air inside the duct in contact with the duct decreases. Particularly in the above-mentioned stagnant part, the flow velocity of air partially lowers, and the temperature is more likely to decrease. As a result, the air inside the duct is not at a constant temperature, but has a temperature gradient in which the portion near the duct wall or stagnation is low and the temperature at the center of the duct is high.

In order to blow air from the plurality of blowoff ports and heat the heated member, the blowout ports are arranged so as to be the position and direction to blow the air onto the heated member. In order to send air to the outlets, a branch duct is provided which branches off from the duct and sends the air to the respective outlets.
When air having the aforementioned temperature gradient flows into the branch ports to the plurality of branch ducts connected to the wall of the duct, first, low temperature air present near the wall of the duct flows first. Then, as the downstream branch port is reached, low-temperature air near the duct wall gradually decreases from the inside of the duct. As a result, only high temperature air will remain inside the duct. And the temperature of the air which flows in to the branch port to a branch duct becomes high, so that it becomes the downstream outlet port. As described above, when the heated air inside the duct is branched and blown out from the plurality of outlets, a temperature difference occurs between the blown air on the upstream side and the downstream side.

A heating furnace according to the present embodiment will be described.
Embodiment
As shown in FIG. 1 (front view), FIG. 2 (right side view), FIG. 3 (BB cross-sectional view) and FIG. 4 (AA cross-sectional view), the heating furnace 100 of the present embodiment has a housing 10 and a blower. A heating duct 30, a heater 40, a distribution duct 50, a branch duct 60, an outlet 70, an exhaust fan 80 and an exhaust pipe 81 are main components. The heating duct 30 and the distribution duct 50 are taken as a first duct, and the branch duct 60 is taken as a second duct.
The whole size is about 1.1 m in width, about 2.2 m in depth, and about 2.4 m in height.

  The housing 10 has a size that can accommodate the blower 20, the heating duct 30, the heater 40, the distribution duct 50, the branch duct 60, and the outlet 70, and the shape is a rectangular solid. The material of the member which comprises the housing | casing 10 can endure the temperature inside a heating furnace, for example, consists of steel. Further, as shown in FIG. 9, a plurality of holes 13 are opened in the bottom of the housing 10.

  The blower 20 is fixed to the housing 10 so as to be disposed on the upper front side (upper left in FIGS. 2 and 4) inside the housing 10. The blower 20 is rotationally driven by a drive source (not shown). The fan 20 rotates its internal blades and sucks the air inside the housing 10 from the air inlet 21, and then sends the air from the air outlet 22 on the back side to the heating duct 30 connected to the air outlet 22. Be The blower 20 has a blowing capacity capable of securing a flow rate of air blown out from a blowout port 70 described later.

The heating duct 30 is connected to the outlet 22 of the blower 20, and is fixed to the housing 10 so as to be disposed inside the housing 10 on the upper back side (upper right in FIGS. 2 and 4). ing. The heating duct 30 has a horizontal portion extending horizontally from the near side to the far side (left to right in FIGS. 2 and 4) and a vertically downward from above on the far side (right in FIGS. 2 and 4) It comprises an extending vertical portion and a bending portion which diverts the flow direction of the internal air between the horizontal portion and the vertical portion. The horizontal cross section on the upstream side and the vertical cross section on the downstream side are quadrangle (0.5 m in width, 0.5 m in height), and the bent part has a cross sectional area equal to or larger than that of the horizontal part and the vertical part. There is.
These cross-sectional areas have a size that can ensure the flow rate of air blown out from the blowout port 70 described later.

  The upstream end 32 of the heating duct 30 is connected to the outlet 22 of the blower 20. The cross-sectional shape of the end portion 32 gradually changes in the vicinity of the connection portion so as to be shaped in accordance with the size and shape of the outlet 22 of the blower 20. Inside the upstream side of the heating duct 30, a heater 40 for heating air is arranged. An outlet 31 is provided on the downstream wall of the heating duct 30.

  The heater 40 has a plurality of sheathed heaters each of which is bent a plurality of times so as to increase the contact area with the air flowing inside the heating duct 30. Each end of the heater 40 is fixed to the upper side wall of the horizontal part of the heating duct 30 so that the heat generating part is inside the heating duct 30. The electrode at the end is wired outside the heating duct 30, and the wire is covered by the wiring box 40a. The amount of heat generated by the heater 40 is sufficient to heat the flow rate of air blown out from the air outlet 70 described later to the set temperature.

  The distribution duct 50 comprises an upstream vertical portion and a downstream horizontal portion. The vertical portion is connected to the connecting portion 33 of the upper heating duct 30 at the connecting portion 53. The downstream horizontal portion is fixed to the housing 10 so as to be disposed in the middle of the inside of the housing 10. The horizontal portion is for sending the air sent from the connecting portion 53 from the back side to the near side (from the right side to the left side in FIGS. 2 and 4). The cross-sectional shape of the horizontal portion is a quadrilateral whose width direction is larger than the height direction. A plurality of branch ports 51 for branching the air in the distribution duct 50 are formed in the side wall 50 a of the horizontal portion of the distribution duct 50. The branch ports 51 are formed at predetermined intervals on both side walls of the horizontal portion of the distribution duct 50, and the spacing is the interval at which the branch ducts 60 are arranged.

  Exhaust ports 52a to 52e are formed in the vicinity of each branch port 51 of the side wall 50a of the horizontal portion of the distribution duct 50 and on the upstream side of the air flowing inside. The discharge ports 52a, 52b and 52d are respectively one long hole, and the discharge ports 52c and 52e are two long holes. At the respective discharge ports 52a to 52e, lids 54a to 54e which are larger than the respective discharge ports 52a to 52e and can close the respective discharge ports 52a to 52e are arranged. Each lid is screwed to the side wall 50a so that the opening area can be adjusted by changing its fixed position. The side cover of the housing 10 is provided with an adjustment window (not shown). The opening area of the discharge ports 52a to 52e can be adjusted by opening the adjustment window, loosening the screws fixing the lids 54a to 54e, and moving the positions of the lids 54a to 54e.

The branch duct 60 is connected and fixed to the branch port 51 of the distribution duct 50. FIG. 5 is a perspective view showing one of the plurality of branch ducts 60 extracted. The upstream side of the branch duct 60 is a horizontal portion directed from the branch port 51 to the outside of the housing 10 and is a vertical portion directed downward after passing through the bent portion, and its end is closed. The cross-sectional shape of the branch duct 60 is a quadrangle in which the length in the direction from the back side to the front side (right to left in FIGS. 2 and 4) is the longitudinal direction.
The branch ducts 60 are arranged four on one side wall of the distribution duct 50 and eight on both sides.

  As shown in FIG. 5, the adjustment valve 61 is disposed inside the horizontal portion of the branch duct 60. The adjustment valve 61 is flat. The shape is similar to the internal cross-sectional shape of the upstream horizontal portion of the branch duct 60, and the size is smaller than the internal cross-sectional shape. In the adjusting valve 61, a shaft 61a is formed in the horizontal direction at a central position in the lateral direction. Both ends of the shaft 61 a protrude from the hole formed in the side wall of the branch duct 60 to the outside of the branch duct 60 and are rotatably supported on the side wall of the branch duct 60. An adjustment fitting 62 is fixed to one end of the shaft 61a. The angle of the adjustment valve 61 is changed by changing the rotation angle of the adjustment fitting 62 located outside the branch duct 60 and fixing it to the branch duct 60. Thereby, the opening area inside the branch duct 60 can be adjusted.

  Holes 64 are formed in the side wall of the vertical portion of each branch duct 60 and in the direction toward the inside of the housing 10. A cylinder 65 is coupled to cover the hole 64. Air guide plates 63a to 63d partially having a bent portion are disposed across the inside of the cylinder 65 and the vertical portion of the branch duct 60. The air guide plates 63a to 63d are disposed horizontally inside the cylinder 65, and obliquely disposed so that the end thereof is on the upper side inside the vertical portion of the branch duct 60. The length of the oblique portion is the shortest so that the air guide plate disposed on the upper side is the shortest and the longer it is disposed on the lower side, but the longest one does not block the vertical portion of the branch duct 60.

  The outlet 70 is formed in a plate 66 fixed so as to close the end of the cylinder 65. The blowout ports 70 are formed in five stages in the vertical direction. The holes formed in the respective stages are arranged at a size and a position where the air in the space formed by the air guide plates 63a to 63d is blown out in the inward direction of the housing 10. The number of the blowout ports 70 in each stage is arranged to be approximately equally dispersed in accordance with the inner shape of the cylinder 65. The tip of the thermocouple 71 is an extension of the hole at the center of the outlet 70, and is disposed at a predetermined distance from the outlet 70.

  The blowout ports 70 are arranged as a pair so as to heat a heated member 93 described later from both sides. The heating furnace 100 has a structure for simultaneously heating four heated members 93, and the outlets 70 are arranged in a row from the near side to the far side (from left to right in FIGS. 2 and 4). ing.

  The exhaust fan 80 is fixed to the upper wall outside of the housing 10. The exhaust pipe 81 connects the hole formed in the upper wall of the housing 10 and the intake port of the exhaust fan 80. The exhaust port of the exhaust fan 80 is open upward.

As shown in FIG. 6, the member to be heated 93 is placed on a stand 90 of the member to be heated 93 drawn out of the heating furnace 100. FIG. 6 shows the holder 90 pulled out of the heating furnace 100.
A rectangular hole 12 is formed in the lower central portion of the front of the housing 10. The width and height of the hole 12 are such that the member 93 to be heated, the mounting table 92 and the base 91 can pass through.

In the mounting table 90, four mounting tables 92 having a shape suitable for arranging the member 93 to be heated are arranged on the upper part of the base 91 having a convex shape at an interval corresponding to the distance between the branch ducts 60. . The height of the mounting table 92 is a height at which the center of the heated member 93 coincides with the center of the blowout port 70 when the heated member 93 is disposed inside the heating furnace 100. At one end of the base 91, a lid 95 of a shape and size that fits into the hole 12 is fixed. The handle 94 is disposed on the lower side of the lid 95 opposite to the base 91.
A convex guide 11 is formed on the inner side of the bottom of the housing 10. The width of the guide 11 is smaller than the inner dimension of the base 91.

After placing the heated member 93 on the mounting table 92, the mounting table 90 is loaded into the inside of the heating furnace 100. The loading table 90 is stored at a predetermined position after the guide 11 and the base 91 are engaged. The heating furnace 100 is closed by the lid 95 by pushing the holder 90 to the end.
FIG. 7 is a perspective view showing a state where the member to be heated 93 is disposed inside the heating furnace 100, and the side cover of the housing 10 is not displayed. The heated member 93 is disposed at a position where the hot air blown from the outlets 70 on both sides is blown.

Next, a method of heating the member 93 to be heated by the heating furnace 100 will be described.
Since the time to heat the member 93 to be heated can be shortened by heating the inside of the heating furnace 100 in advance, this preheating method will be described.

The blades of the blower 20 are rotated to take in the air inside the housing 10 from the air inlet 21 and send the air to the heating duct 30. The heater 40 heats the air sent to the heating duct 30. The heated air is sent from the horizontal part of the heating duct 30 to the bending part and further to the vertical part. The air moved from the connection portion 33 of the heating duct 30 to the connection portion 53 of the distribution duct 50 is sent from the vertical portion of the distribution duct 50 to the horizontal portion. The air sent to the horizontal part of the distribution duct 50 is sent from the respective branch ports 51 to the respective branch ducts 60. The air sent to each branch duct 60 is blown out to the inside of the housing 10 from each outlet 70. The air blown out inside the housing raises the internal ambient temperature of the housing 10 and then is drawn from the air inlet 21 of the blower 20 again. Thus, the air circulates inside the housing 10.
The heating method of the heating furnace 100 is a method of circulating and heating the air inside the housing 10 which has already been heated, and blowing the air to the heated member 93. This method can reduce energy consumption as compared with a heating method in which the outside air is heated and sprayed to the heated member 93, and the inside of the housing 10 can be preheated efficiently.

  The temperature of the air heated by the heater 40 is higher than the ambient temperature inside the housing 10. Therefore, the temperature of the wall of the heating duct 30 disposed inside the housing 10 is lower than that of the heated air. The air heated by the heater 40 lowers the temperature of the portion in contact with the wall of the heating duct 30. The air whose temperature has dropped is discharged to the outside of the heating duct 30 (the inside of the housing 10) from the outlet 31 formed in the wall of the heating duct. Since the air discharged to the outside of the heating duct 30 is also higher in temperature than the atmospheric temperature inside the casing 10, it is used to raise the atmospheric temperature inside the casing 10.

The method of suppressing the temperature difference of the air which blows off from each outlet 70 after pre-heating completion is demonstrated.
The temperature of the air blown out from the blowout port 70 is measured by the thermocouple 71, respectively. From the measurement results, the blowout port 70 for blowing out the lowest temperature air among them is specified. For example, it is assumed that the outlet from which the air with the lowest temperature is blown out is the outlet 70 disposed on the far side (right side in FIGS. 2 and 4). The branch duct 60 having the air outlet 70 is for branching air from the branch port 51 on the innermost side (right side in FIGS. 2 and 4) of the distribution duct 50.

  The discharge port disposed on the upstream side of the branch port 51 is a discharge port 52e. As described above, the discharge port 52e has a shape in which two long holes are arranged so that the opening area can be increased. In the initial state, as shown in FIG. 8A, the outlet 52e is closed by the lid 54e. A side cover (not shown) of the housing 10 is opened, and a screw or the like fixed to the wall surface of the distribution duct 50 of the cover 54e is loosened using a jig, for example, and the cover 54e is partially opened by the discharge port 52e. The lid 54e is again fixed to the wall surface of the distribution duct 50, as shown in FIG. 8 (B). From the discharge port 52e, the air cooled by the wall surface of the heating duct 30 is discharged to the outside of the distribution duct 50 (inside the housing 10). The air is at a higher temperature than the air inside the housing 10, and thus serves to raise the ambient temperature inside the housing 10.

Thereafter, the temperature of the air blown out from the corresponding outlet 70 is measured again, and the temperature difference with the other outlets 70 is measured. If the temperature of the air blown out from the blowout port 70 is still the lowest and the difference with the temperature of the air blown out from the other blowout ports 70 exceeds the set range, the position of the lid 54e is shifted again to discharge the air. The opening area of the outlet 52e is readjusted. By performing this operation on all the necessary outlets 52a to 52e, the temperature of the air blown out from all the outlets 70 is made within the predetermined range.
The adjustment is completed when the temperature of the air blown out from all the blowout ports 70 falls within a predetermined range.

  Further, the volume of air blown out from each outlet 70 is measured by a separately prepared air flow meter, and the flow rate of air blown out from each outlet is adjusted. Specifically, as shown in FIG. 5, by adjusting the angle of the adjustment valve 61 disposed upstream of the branch duct 60 having the outlet 70 with a large air volume, the internal opening area of the corresponding branch duct 60 is reduced. Do. In addition, the angle of the adjustment valve 61 disposed upstream of the branch duct 60 having a small air flow rate outlet 70 is adjusted to increase the internal opening area of the branch duct 60. This is possible by changing the angle at which the adjustment fitting 62 attached to the branch duct 60 is fixed to the branch duct 60. Thereby, the air volume of the air which blows off from all the blowing ports 70 is made into the predetermined range.

  Although not shown, by opening adjustment windows opened in the housing 10 at the respective adjustment locations, for example, it is possible to perform adjustment manually by using a jig or the like.

  When the temperature of the air blown out from the outlet 70 measured by the thermocouple 71 becomes excessively higher than the set value, the amount of heat generation of the heater 40 is reduced. In addition, when the ambient temperature inside the housing 10 becomes excessively higher than the set value, the exhaust fan 80 is operated to discharge the air inside the housing 10 to the outside of the housing 10. As a result, the air pressure inside the housing 10 is reduced, the outside air is taken in from the hole 13 formed in the bottom of the housing 10, and the ambient temperature inside the housing 10 is lowered.

  After the temperature inside the housing 10 is stabilized, and the temperature difference between the air blown out from the outlets 70 is adjusted within a predetermined range, the holding table 90 is held outside the housing 10 by holding the handle 94. Pull out. The heated member 93 is placed on the drawn-out mounting table 92, and the mounting table 90 is returned to the inside of the housing 10.

  The air blown from the respective blow-out ports 70 to the respective members to be heated 93 has no variation in temperature, so that the members to be heated 93 are heated by the same amount of heat. Moreover, since the temperature of the member 93 to be heated does not become higher than the temperature of the air to be blown, the control of the heating temperature also becomes easy.

  As mentioned above, in the heating furnace of this invention, the temperature difference of the air sprayed on a to-be-heated member can be suppressed, and a to-be-heated member can be heated uniformly.

(Modification)
In the above embodiment, the opening area of the corresponding portion was manually adjusted in order to make the temperature of the air discharged from each outlet constant, but a mechanism for automatically adjusting the opening area of the outlet It may be adopted.

  For example, as shown in FIGS. 10A to 10C, a lid 230 for closing the discharge port 52a is slidably held by the guide 240 in the vertical direction at both ends. An elongated hole 231 is formed in the upper part of the lid 230 at a position partially separated from the wall surface of the distribution duct 50 in the horizontal direction. The pin 211 is inserted in the long hole. The pin 211 is formed on the crank 210, and the rotation shaft of the motor 200 is fixed to the crank 210 at a position offset from the pin 211. The motor 200 is fixed to the wall surface of the distribution duct 50 via a mounting bracket 220. By rotating the rotation shaft of the motor 200, the position of the pin 211 rotates about the rotation shaft of the motor 200. By rotational movement of the pin 211, the lid 230 moves up and down.

  FIG. 10A shows a state in which all the discharge ports 52a are closed. Since the outlet 52a is not open, air is not exhausted from the outlet 52a. FIG. 10B shows a state where the discharge port 52a is opened about half. Since the opening area is half, an amount of air corresponding to the opening area is discharged. FIG. 10C shows a state in which all the discharge ports 52a are open. The opening area is about twice that in FIG. 10B, and the amount of air corresponding to the opening area is discharged.

(Another modification)
Although the above-mentioned embodiment demonstrated the method to make a to-be-heated member higher than external temperature, the structure of this invention can be used also for cooling a member.
Instead of the heater 40, a cooler is disposed inside the heating duct 30 to cool the air, make the temperature of the cooled air blown out from the outlet 70 constant as described above, and blow the cooled air onto the member to be cooled Thus, it is also possible to uniformly cool the member to be cooled.

DESCRIPTION OF SYMBOLS 10 housing | casing 20 air blower 30 heating duct 40 heater 50 distribution duct 60 branch duct 70 discharge port 80 exhaust fan 90 mounting base 100 heating furnace

Claims (3)

A heating furnace which blows heated air to a heated member to heat it, and
A first duct that is a flow path of air;
A blower for delivering air to the first duct;
A heater for heating the air in the first duct;
A plurality of second ducts connected to the first duct to branch heated air and having an outlet for blowing the heated air to the heated member;
A housing including the first duct, the blower, and the plurality of second ducts;
Have
The first duct has an outlet for discharging a part of the heated air into the housing at a position upstream of the connecting portion with the second duct and downstream of the heater. Prepare,
heating furnace. The outlet has a lid covering the outlet, and the opening area of the outlet is adjusted by moving the position of the lid.
The heating furnace according to claim 1. Inside a housing containing a first duct, a blower, and a plurality of second ducts,
Air is sent to the first duct by the blower;
The air in the first duct is heated by a heater,
Branching the heated air to the plurality of second ducts connected to the first duct;
A portion of the heated air is discharged into the housing from an outlet at a position downstream of the heater on the upstream side of the connecting portion with the second duct included in the first duct. ,
The heated air is blown to the member to be heated from the outlets of the plurality of second ducts,
A method of blowing heated air to a member to be heated for heating.

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