Patent Publication Number: US-10774397-B2

Title: Heat treatment apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a heat treatment apparatus for applying heat treatment and cooling treatment to a workpiece. 
     BACKGROUND ART 
     For example, a heat treatment apparatus for applying heat treatment to a metallic component (workpiece), etc., is known (for example, refer to Patent Application Document 1). A quenching device as a heat treatment apparatus described in Patent Application Document 1 is configured to apply quenching treatment (rapid cooling) to a heated workpiece. In the rapid cooling treatment, the workpiece is disposed within a portion extending vertically in a duct. Then, by a coolant passing through this duct, the workpiece is cooled. 
     CITATION LIST 
     Patent Application Document 
     Patent Application Document: Japanese Unexamined Patent Application Publication No. 2005-213646 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     A workpiece is let into and out of a duct by being displaced along an axial direction (up-down direction) of an opening of the duct. In the configuration described in Patent Application Document 1, a heating furnace is disposed above the duct. Therefore, the heating furnace, a conveyance path to convey the workpiece from the heating furnace to the duct, and the duct are arranged vertically, and this increases the size of the apparatus. 
     In view of the circumstances described above, an object of the present invention is to provide a heat treatment apparatus capable of being configured to be more compact. 
     Solution to Problem 
     (1) In order to solve the above-described problem, a heat treatment apparatus according to an aspect of the present invention includes a coolant passage defining body to define a coolant passage to supply a predetermined coolant to a workpiece passing through a conveyance path along a predetermined conveyance direction, wherein the coolant passage defining body includes a plurality of coolant passage defining members, and the plurality of coolant passage defining members are configured to define the coolant passage in a state of housing the workpiece by being displaced to approach each other along a predetermined crossing direction crossing the conveyance direction, and configured to allow the workpiece to be let into and out of the coolant passage along the conveyance direction by being displaced to separate from each other along the crossing direction. 
     With this configuration, an extending direction of the coolant passage and the conveyance direction of the workpiece are different from each other. Accordingly, the shape of the heat treatment apparatus can be prevented from becoming excessively long in any of the extending direction of the coolant passage and the conveyance direction. Therefore, the heat treatment apparatus can be made more compact. In addition, by relatively displacing the plurality of coolant passage defining members to separate from each other in a predetermined crossing direction, the workpiece is enabled to be let into and out of the coolant passage. Therefore, it is not necessary to provide a robot arm, etc., to let the workpiece into and out of the coolant passage. Accordingly, the heat treatment apparatus can be made more compact. 
     (2) Preferably, the coolant passage extends along the crossing direction, the crossing direction includes an up-down direction of the heat treatment apparatus, and the coolant passage is configured so that a cooling liquid as the coolant flows upward from a lower side in the coolant passage. 
     With this configuration, the crossing direction and the conveyance direction are disposed orthogonal to each other. Accordingly, the coolant passage defining body can be formed to be vertically long, so that the size of the heat treatment apparatus in the horizontal direction can be made smaller. In addition, since an extending direction of a supply pipe and the conveyance direction are orthogonal to each other, the heat treatment apparatus can be prevented from being shaped excessively large in each of the horizontal direction and the vertical direction. Therefore, the heat treatment apparatus can be made more compact. Further, in the coolant passage, a coolant flows upward from the lower side, so that the coolant can be more uniformly moved up. Accordingly, the workpiece can be more uniformly cooled. 
     (3) More preferably, the heat treatment apparatus further includes a conveyance tray to convey the workpiece along the conveyance direction, wherein the conveyance tray cooperates with the plurality of coolant passage defining members, which is configured to define the coolant passage. 
     With this configuration, the conveyance tray defines apart of the coolant passage. Accordingly, an exclusive member to support the conveyance tray inside the coolant passage is unnecessary, so that the heat treatment apparatus can be configured to be more compact and simpler. 
     (4) More preferably, the conveyance tray is configured to be disposed between the plurality of coolant passage defining members, and the conveyance tray includes a support portion to support the workpiece, and a hole portion to make the coolant pass through. 
     With this configuration, the workpiece is disposed at an intermediate portion of the coolant passage. Then, a coolant is supplied to this workpiece through the hole portion. Accordingly, the workpiece is reliably cooled by the coolant while being reliably supported inside the coolant passage. 
     (5) Preferably, the plurality of coolant passage defining members include an upper member and a lower member disposed below the upper member, and the heat treatment apparatus further includes a vertical displacement mechanism to displace the upper member in the up-down direction with respect to the lower member. 
     With this configuration, by displacing the upper member to the lower member side by the vertical displacement mechanism, a coolant passage is formed. In addition, by moving up the upper member away from the lower member by the vertical displacement mechanism, a workpiece can be exposed from the coolant passage defining body. This enables letting-in and letting-out of the workpiece along the conveyance direction. 
     (6) More preferably, the heat treatment apparatus further includes a conveyance mechanism to displace the conveyance tray along the conveyance direction, wherein the conveyance mechanism includes a unit configured to be displaceable to a predetermined conveyance position and a predetermined cooling position by the vertical displacement mechanism, and the unit positioned at the conveyance position supports the conveyance tray so that the conveyance tray is away from the upper member and the lower member, and the unit positioned at the cooling position disposes the conveyance tray so that the conveyance tray comes into contact with the lower member. 
     With this configuration, when the unit is disposed at the conveyance position, the unit can support the conveyance tray in a state where this conveyance tray does not collide with other members. Accordingly, the conveyance tray can be smoothly conveyed. On the other hand, when the unit is disposed at the cooling position, the conveyance tray can be disposed so as to define a coolant passage in cooperation with the lower member. Thus, the vertical displacement mechanism not only simply displaces the upper member vertically with respect to the lower member, but also displaces the unit and the conveyance tray vertically. 
     (7) More preferably, the vertical displacement mechanism is configured to displace the upper member to bring the upper member into contact with the conveyance tray when the conveyance tray is positioned at the cooling position. 
     With this configuration, by displacing the upper member downward by the vertical displacement mechanism, the upper member and the lower member can be made to sandwich the conveyance tray. As a result, a coolant passage can be defined by cooperation of the upper member, the conveyance tray, and the lower member. 
     (8) Preferably, the heat treatment apparatus further includes a rectifying member to rectify the coolant inside the coolant passage. 
     With this configuration, a larger amount of coolant can be more uniformly brought into contact with a workpiece per unit time, so that distortion of the workpiece can be suppressed. 
     Effect of the Invention 
     According to the present invention, a more compact heat treatment apparatus can be realized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic and conceptual perspective view of a heat treatment apparatus, partially cut away. 
         FIG. 2  is a front view of a heating device of the heat treatment apparatus. 
         FIG. 3  is an inlet-side side view of the heating device. 
         FIG. 4  is an outlet-side side view of the heating device. 
         FIG. 5  is a back view of the heating device. 
         FIG. 6  is a partial sectional view of a major portion of the heating device, viewed from a front side. 
         FIG. 7  is a sectional view in a state where the major portion of the heating device is shown in a plan view. 
         FIG. 8  is a side view of an outlet side of an intermediate door unit of the heat treatment apparatus. 
         FIG. 9  is a front view of a cooling device of the heat treatment apparatus. 
         FIG. 10  is a side view of an outlet side of the cooling device. 
         FIG. 11  is a back view of the cooling device. 
         FIG. 12  is a sectional view taken along line XII-XII in  FIG. 11 , showing a section orthogonal to a conveyance direction of a work piece. 
         FIG. 13  is an enlarged view of a major portion of  FIG. 12 . 
         FIG. 14  is a sectional view taken along line XIV-XIV in  FIG. 10 , showing the cooling device viewed from the front side. 
         FIG. 15  is a view to describe a cooling treatment operation in the cooling device. 
         FIG. 16  is a view to describe a cooling treatment operation in the cooling device. 
         FIG. 17  is a schematic configuration diagram of the heat treatment apparatus to describe an effect of the heat treatment apparatus. 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     Hereinafter, an embodiment to carry out the present invention is described with reference to the drawings. The present invention can be widely applied as a heat treatment apparatus for applying heat treatment to a workpiece. 
       FIG. 1  is a schematic and conceptual perspective view of a heat treatment apparatus  1 , partially cut away.  FIG. 2  is a front view of a heating device  4  of the heat treatment apparatus  1 .  FIG. 3  is an inlet-side side view of the heating device  4 .  FIG. 4  is an outlet-side side view of the heating device  4 .  FIG. 5  is a back view of the heating device  4 .  FIG. 6  is a partial sectional view of a major portion of the heating device  4 , viewed from the front side.  FIG. 7  is a sectional view in a state where the major portion of the heating device  4  is shown in a plan view.  FIG. 8  is a side view of an outlet side of an intermediate door unit  5  of the heat treatment apparatus  1 . 
       FIG. 9  is a front view of a cooling device  6  of the heat treatment apparatus  1 .  FIG. 10  is aside view of an outlet side of the cooling device  6 .  FIG. 11  is a back view of the cooling device  6 .  FIG. 12  is a sectional view taken along line XII-XII in  FIG. 11 , showing a section orthogonal to a conveyance direction A 1  of a workpiece  100 .  FIG. 13  is an enlarged view of a major portion of  FIG. 12 .  FIG. 14  is a sectional view taken along line XIV-XIV in  FIG. 10 , showing the cooling device  6  viewed from the front side.  FIG. 15  and  FIG. 16  are views to describe a cooling treatment operation in the cooling device  6 . 
     Hereinafter, based on a state where the heat treatment apparatus  1  is viewed from the front, the left-right direction X 1  (conveyance direction A 1 ), the front-rear direction Y 1 , and the up-down direction Z 1  are prescribed. 
     Referring to  FIG. 1  and  FIG. 2 , the heat treatment apparatus  1  is provided for applying heat treatment to the workpiece  100 . This heat treatment includes heat applying treatment and cooling treatment. Examples of heat applying treatment include carburizing heat treatment and heat equalizing treatment, etc. Examples of cooling treatment include quenching treatment, etc. Detailed examples of heat applying treatment and cooling treatment to be performed in the heat treatment apparatus  1  are not particularly limited. In the present embodiment, the workpiece  100  is a metallic component, for example, a gear. 
     The heat treatment apparatus  1  includes a conveyance tray  2 , a first conveyance mechanism  3 , a heating device  4 , an intermediate door unit  5 , and a cooling device  6 . 
     The conveyance tray  2  is a conveyance support member to support the workpiece  100 . The conveyance tray  2  is, in the present embodiment, a member made of metal or carbon, and is repeatedly used in heat treatment of the workpiece  100  in the heat treatment apparatus  1 . The conveyance tray  2  conveys the workpiece  100  along a predetermined conveyance direction A 1  extending along the horizontal direction. In the present embodiment, when heat applying treatment is applied to the workpiece  100  in the heating device  4 , the conveyance tray  2  is away from the workpiece  100  so as to be prevented from being exposed to high heat from the heating device  4 . 
     The conveyance tray  2  includes a frame portion  2   a  and support portions  2   b.    
     The frame portion  2   a  is provided as a portion to be supported by the first conveyance mechanism  3 . The frame portion  2   a  is formed into, for example, a plate shape having a rectangular external form and a predetermined thickness. The frame portion  2   a  is formed to have a size that can be housed inside the heating device  4  and housed inside the cooling device  6 . At a central portion of the frame portion  2   a , a hole portion  2   c  (opening) is formed. This hole portion  2   c  is formed to be, for example, circular, and penetrates through the frame portion  2   a  in a thickness direction of the frame portion  2   a . This hole portion  2   c  is provided to move up and down the workpiece  100  in the heating device  4 , and provided to allow a coolant to pass through in the cooling device  6 . 
     For example, from an inner circumferential portion of the hole portion  2   c  toward a center of the hole portion  2   c , a plurality of support portions  2   b  extend. The support portions  2   b  are provided as portions to support the work piece  100 . The support portions  2   b  are provided in plural (in the present embodiment, three) at even intervals in the circumferential direction of the hole portion  2   c . Each support portion  2   b  extends from the rim of the hole portion  2   c  toward the central portion of the hole portion  2   c . Tip ends of these support portions  2   b  are away from each other so as not to block an operation of lifting the workpiece  100  by a second conveyance mechanism  18  described below. 
     On each support portion  2   b , a positioning projection  2   d  to position (center) the workpiece  100  is provided. The projections  2   d  are disposed to receive an outer circumferential surface of the workpiece  100 , and extend upward. The workpiece  100  is preferably placed on the support portions  2   b  by point contact or linear contact. The support portions  2   b  function as rectifying members to rectify a coolant in a coolant passage  48  as described below. Batch treatment can be performed by stacking a plurality of workpieces  100  on the conveyance tray  2 . 
     The conveyance tray  2  configured as described above is conveyed along the conveyance direction A 1  to the heating device  4  and the cooling device  6  by the first conveyance mechanism  3 . The first conveyance mechanism  3  is provided to convey the conveyance tray  2  along a predetermined conveyance path B 1  from the outside of the heating device  4  to the outside of a cooling chamber  8  through a heating chamber  7  of the heating device  4  and the cooling chamber  8  of the cooling device  6 . This first conveyance mechanism  3  is configured to circulate the conveyance tray  2  along the conveyance path B 1  to the outside of the heating device  4 , the inside of the heating chamber  7  of the heating device  4 , the inside of the cooling chamber  8  of the cooling device  6 , and the outside of the cooling chamber  8 . 
     Referring to  FIG. 1  to  FIG. 7 , the first conveyance mechanism  3  includes a heating chamber-side conveyance portion  11  disposed in the heating chamber  7  to convey the conveyance tray  2  along the conveyance path B 1 , a cooling chamber-side conveyance portion  12  disposed in the cooling chamber  8  at a position away from the heating chamber-side conveyance portion  11  to convey the conveyance tray  2  along the conveyance path B 1 , and an intermediate conveyance portion  13  disposed between the heating chamber-side conveyance portion  11  and the cooling chamber-side conveyance portion  12 . 
     The heating chamber-side conveyance portion  11  is provided to convey the conveyance tray  2  inside the heating chamber  7 . The cooling chamber-side conveyance portion  12  is provided to convey the conveyance tray  2 , that passed through the heating chamber  7 , inside the cooling chamber  8 . The intermediate conveyance portion  13  is provided to dispose the conveyance tray  2  along the conveyance direction A 1  in an intermediate door unit  5 . Details of the first conveyance mechanism  3  are described below. 
     The heating device  4  includes the heating chamber  7 , a bottom portion  14 , columnar supports  15 , an inlet door unit  16 , a heating member  17 , and a second conveyance mechanism  18 . 
     The bottom portion  14  is provided as a base member of the heating device  4 . The bottom portion  14  is formed to be rectangular in a plan view, and from the bottom portion  14 , a plurality of columnar supports  15  extend upward. The columnar supports  15  support the heating chamber  7 . 
     The heating chamber  7  is provided to provide heat energy to the workpiece  100 . The heating chamber  7  is formed into a rectangular parallelepiped box shape. For example, the heating chamber  7  is configured for applying, in a state vacuated by a vacuum pump not shown in the drawings, heat treatment to the workpiece  100 . The heating chamber  7  has an inlet wall  7   a , an outlet wall  7   b , a front wall  7   c , a rear wall  7   d , a top wall  7   e , and a bottom wall  7   f.    
     In the inlet wall  7   a , an inlet  7   g  (opening) to introduce the workpiece  100  into the heating chamber  7  is formed. The inlet  7   g  is disposed close to a lower portion of the inlet wall  7   a , extends to be long and narrow from the front wall  7   c  side to the rear wall  7   d  side, and allows the workpiece  100  to pass through. This inlet  7   g  is opened and closed by the inlet door unit  16 . 
     The inlet door unit  16  includes an inlet door  19  and an inlet door opening and closing mechanism  20 . 
     The inlet door  19  is a plate-shaped member disposed along an outer surface of the inlet wall  7   a . The inlet door  19  closes the inlet  7   g  when being disposed at a closed position. In addition, the inlet door  19  opens the inlet  7   g  when being disposed at an open position. The inlet door  19  is provided with a sealing structure made of NBR (natural rubber), fluorine-containing rubber, etc., and configured to seal an atmosphere gas and a coolant in the heat treatment apparatus  1 . The inlet door  19  is operated to open and close by the inlet door opening and closing mechanism  20 . 
     The inlet door opening and closing mechanism  20  is formed, in the present embodiment, by using a fluid pressure cylinder, and includes a cylinder supported by the bottom portion  14  and a rod projecting from the cylinder and joined to the inlet door  19 . According to a change in projecting amount of the rod from the cylinder, the inlet door  19  opens or closes. The inlet door  19  is sandwiched by a pair of front and rear guides  21  provided on an outer surface of the inlet wall  7   a  and extending vertically, and displacement of the inlet door  19  in the up-down direction Z 1  is guided. In a state where the inlet door  19  is opened, the workpiece  100  that passed through the inlet  7   g  of the heating chamber  7  is conveyed to the inside of the heating chamber  7  by the heating chamber-side conveyance portion  11 . 
     The heating chamber-side conveyance portion  11  is disposed inside the heating chamber  7 . This heating chamber-side conveyance portion  11  is a belt conveyor type conveyance portion. 
     The heating chamber-side conveyance portion  11  includes a heating chamber-side motor  22  as a drive source disposed outside the heating chamber  7 , an output transmitting member  23  that transmits an output of the heating chamber-side motor  22  from the outside of the heating chamber  7  to the inside of the heating chamber  7  at a predetermined fixed position, a drive shaft  25  and a driven shaft  26  to be rotated by the output transmitting member  23 , and a pair of chains  27  (drive members) that are disposed inside the heating chamber  7  and displace the conveyance tray  2  in the conveyance direction A 1  by receiving power from the output transmitting member  23 . 
     The heating chamber-side motor  22  is, for example, an electric motor. The heating chamber-side motor  22  is disposed on a downstream side in the conveyance direction A 1  in the heating chamber  7  at the rear (outer surface side) of the rear wall  7   d  of the heating chamber  7 . A housing  22   a  of the heating chamber-side motor  22  is fixed to the rear wall  7   d  by using a fixing member such as a bolt. Between the housing  22   a  and the rear wall  7   d , a sealing member (not shown) is disposed, and the sealing member seals airtightly a portion between the housing  22   a  and the rear wall  7   d.    
     To an output shaft (not shown) of the heating chamber-side motor  22 , one end portion of the output transmitting member  23  is joined rotatably in a coordinated manner. In detail, the output shaft of the heating chamber-side motor  22  is directed upward in the up-down direction Z 1 , and the output transmitting member  23  is directed in the front-rear direction Y 1  (horizontal direction). These output shaft and output transmitting member  23  are joined rotatably in a coordinated manner via a mechanism of a gear pair with intersecting axes such as a bevel gear pair. 
     The output transmitting member  23  extends inside the heating chamber  7  through a hole portion  7   i  formed in the rear wall  7   d , at a fixed position close to a lower portion of the heating chamber  7 . To the other end portion of the output transmitting member  23 , a sprocket is joined integrally rotatable. The drive shaft  25  is disposed adjacent to the output transmitting member  23 . The drive shaft  25  is disposed on a downstream side of the heating chamber  7  in the conveyance direction A 1 . The drive shaft  25  extends along the front-rear direction orthogonal to the conveyance direction A 1 . To one end portion of the drive shaft  25 , a sprocket is joined rotatably together. Around the sprocket of the output transmitting member  23  and the sprocket of the drive shaft  25 , a chain  29  is wound. According to the configuration described above, an output of the heating chamber-side motor  22  is transmitted to the drive shaft  25 . 
     The driven shaft  26  is disposed parallel to the drive shaft  25 . The driven shaft  26  is disposed near the inlet  7   g  of the heating chamber  7 . The drive shaft  25  and the driven shaft  26  are respectively supported rotatably by the bottom wall  7   f  via support members  28  and  28  including bearings, etc. To a pair of end portions of the drive shaft  25  in the front-rear direction Y 1  and a pair of end portions of the driven shaft  26  in the front-rear direction Y 1 , sprockets are respectively joined rotatably together. Around these pairs of sprockets arranged side by side in the conveyance direction A 1 , chains  27  and  27  are wound. The pair of chains  27  and  27  are disposed away from each other in the front-rear direction Y 1 , and are configured to enable the frame portion  2   a  of the conveyance tray  2  to be placed on the pair of chains  27  and  27 . 
     In the present embodiment, in the front-rear direction Y 1 , a distance between the chains  27  and  27  is set to be equal to or longer than an entire length of the workpiece  100 . With the configuration described above, according to driving of the heating chamber-side motor  22 , the output transmitting member  23  rotates, and this rotation is transmitted to one drive shaft  25 . Then, this drive shaft  25  drives the chains  27  and  27  and rotates the driven shaft  26 . That is, according to driving of the heating chamber-side motor  22 , the pair of chains  27  and  27  rotate. Accordingly, the conveyance tray  2  on the pair of chains  27  and  27  are conveyed in the conveyance direction A 1 . 
     At an intermediate portion of the heating chamber  7  in the conveyance direction A 1 , the heating member  17  is disposed, and further, at a lower end portion of the heating chamber  7  and below the heating chamber  7 , the second conveyance mechanism  18  is disposed. That is, the second conveyance mechanism  18  is disposed below the first conveyance mechanism  3  (horizontal conveyance mechanism). As described below, a part of the coolant passage  48  of the cooling device  6  is disposed at a height position lower than a height position of the heating chamber  7 . Accordingly, the heat treatment apparatus  1  can be made more compact. 
     The heating member  17  is a member disposed away from the conveyance path B 1  along a direction (up-down direction Z 1 ) crossing the conveyance direction A 1  in the heating chamber  7  to heat the workpiece  100 . The heating member  17  is disposed, in the present embodiment, above the conveyance path B 1 . The heating member  17  is, in the present embodiment, an induction heating coil, and is configured to heat the workpiece  100  by induction heating. 
     The heating member  17  is configured by forming a conductive member such as copper in a spiral manner. A spiral portion of the heating member  17  is formed into a size capable of surrounding the workpiece  100 . One end portion and the other end portion of the heating member  17  extend linearly rearward, and are supported by the rear wall  7   d . One end portion and the other end portion of the heating member  17  are electrically connected to a power source (not shown), and is supplied with electric power from this power source. Below the heating member  17 , the second conveyance mechanism  18  is disposed. 
     The second conveyance mechanism  18  is provided to move up and down the workpiece  100  between the conveyance tray  2  and the heating member  17  in the heating chamber  7 . 
     The second conveyance mechanism  18  includes a support portion  18   a  to support the workpiece  100 , and a support portion drive mechanism  30  to displace this support portion  18   a  between the conveyance tray  2  and the heating member  17 . 
     The support portion  18   a  of the second conveyance mechanism  18  is provided to lift the workpiece  100  through the hole portion  2   c  formed in the conveyance tray  2 , in the heating chamber  7 . The support portion  18   a  is configured to move up and down between a predetermined standby position P 1  and a heating position P 2 . The support portion  18   a  is formed by using a material with excellent heat resistance such as carbon, metal, or ceramic. The support portion  18   a  at the standby position P 1  is disposed between the pair of chains  27  and  27  of the heating chamber-side conveyance portion  11 . In the present embodiment, the support portion  18   a  is disposed at a substantially center of the heating chamber  7  in the conveyance direction A 1 . 
     The support portion  18   a  is shaped to become capable of lifting the workpiece  100  supported by the conveyance tray  2 , without contact with the conveyance tray  2 . In detail, the support portion  18   a  includes a shaft-shaped support portion main body  18   b , and support portion arms  18   c  extending radially from the support portion main body  18   b . The support portion main body  18   b  at a standby position P 1  is disposed near the bottom wall  7   f  of the heating chamber  7 . 
     The support portion arms  18   c  are disposed, for example, at even intervals in the circumferential direction of the support portion main body  18   b  so that the support portion arms  18   c  and the support portions  2   b  of the conveyance tray  2  that has reached a position above the standby position P 1  are alternately arranged in the circumferential direction of the support portion main body  18   b . At the center of the hole portion  2   c  of the conveyance tray  2 , the components of the conveyance tray  2  are not disposed, and this configuration prevents the support portion main body  18   b  from coming into contact with the conveyance tray  2 . The support portion main body  18   b  is joined to the support portion drive mechanism  30 . 
     The support portion drive mechanism  30  is provided to displace the support portion  18   a  between the standby position P 1  and the heating position P 2 . In the present embodiment, the support portion drive mechanism  30  is formed by using a screw mechanism. Examples of this screw mechanism include a so-called bearing nut mechanism configured by using a bearing as a nut on an outer circumference of a male threaded shaft, and a ball screw mechanism, etc. 
     Further, the support portion drive mechanism  30  includes a rotation mechanism to rotate the support portion  18   a  around a central axis of the support portion  18   a . Note that, the detailed configuration of the support portion drive mechanism  30  is not limited as long as it can displace the support portion  18   a  in the up-down direction Z 1 , can hold the support portion  18   a  at the standby position P 1  and the heating position P 2 , and can rotate the support portion  18   a  (workpiece  100 ) at the heating position P 2 . 
     The support portion drive mechanism  30  includes a main body portion  30   a , a movable portion  30   b , and a drive source  30   c.    
     The main body portion  30   a  is disposed in a space below the heating chamber  7 , and supported by the bottom portion  14 . The main body portion  30   a  is disposed adjacent to a drive source  30   c  such as an electric motor. The drive source  30   c  is supported by the bottom portion  14 . The main body portion  30   a  displaces the movable portion  30   b  in the up-down direction Z 1  by receiving an output from the drive source  30   c . The movable portion  30   b  is supported by the main body portion  30   a , and extends upward from the main body portion  30   a . The movable portion  30   b  is disposed to penetrate through a cylinder portion  31  fixed to the bottom wall  7   f  of the heating chamber  7  and penetrate through the bottom wall  7   f . A bottom portion of the cylinder portion  31  is disposed to surround the movable portion  30   b.    
     With the configuration of the support portion drive mechanism  30  described above, after the conveyance tray  2  and the workpiece  100  are conveyed to a position above the standby position P 1  (below the heating member  17 ) by the heating chamber-side conveyance portion  11  of the first conveyance mechanism  3 , the movable portion  30   b  of the support portion drive mechanism  30  moves upward. According to this movement, the support portion  18   a  moves upward from the standby position P 1 , lifts the workpiece  100 , and further moves to the heating position P 2 . Then, by induction heating by the heating member  17 , the workpiece  100  is heated to a predetermined carburization temperature. 
     At this carburizing, the movable portion  30   b  rotates the support portion  18   a  and the workpiece  100  around the central axis of the support portion  18   a  so that the workpiece  100  can be more uniformly inductively heated. When the operation of heating the workpiece  100  is completed, the movable portion  30   b  immobilizes the support portion  18   a  and the workpiece  100  at a predetermined rotation position (a position around the central axis of the support portion  18   a ). Positional control in this case is performed by a sensor and a control device that are not shown. 
     After the immobilizing, the movable portion  30   b  of the support portion drive mechanism  30  is moved downward, and accordingly, the support portion  18   a  and the workpiece  100  move downward from the heating position P 2 . Then, the workpiece  100  is placed on the support portions  2   b  of the conveyance tray  2 . After that, the support portion  18   a  is further displaced downward to the standby position P 1 . For example, by a detection portion installed on the conveyance tray  2  and a sensor that detects a state of this detection portion, positional control of the support portion  18   a  in the up-down direction Z 1  is performed. Accordingly, without heating the conveyance tray  2  by the heating member  17 , heat treatment can be applied to the workpiece  100 . 
     The conveyance tray  2  and the workpiece  100  after being subjected to heat treatment are conveyed to the intermediate door unit  5  side by the heating chamber-side conveyance portion  11 . 
     The intermediate door unit  5  is configured to be capable of closing to seal airtightly and liquid-tightly between the outlet  7   h  formed in the outlet wall  7   b  of the heating chamber  7  and the inlet  8   g  formed in an inlet wall  8   a  of the cooling chamber  8 , and to be capable of making these outlet  7   h  and inlet  8   g  open. 
     Referring to  FIG. 6  to  FIG. 8 , the intermediate door unit  5  includes a frame portion  5   a , an intermediate door  33 , and an intermediate door opening and closing mechanism  34 . 
     The frame portion  5   a  is a portion assuming a substantially rectangular frame shape as a whole disposed between the heating device  4  and the cooling device  6 , and extends along the conveyance direction A 1 . The frame portion  5   a  is fixed to the outlet wall  7   b  of the heating chamber  7 , and fixed to the inlet wall  8   a  of the cooling chamber  8 . 
     The outlet wall  7   b  of the heating chamber  7  is provided as a wall portion dividing the heating chamber  7  and the cooling chamber  8 . The outlet wall  7   b  of the heating chamber  7  is formed into, for example, a rectangular plate shape. At a portion closer to a lower portion of the outlet wall  7   b  of the heating chamber  7 , the outlet  7   h  is formed. This outlet  7   h  is provided as a rectangular opening, and communicates with both of the space inside the heating chamber  7  and the space inside the cooling chamber  8 . This outlet  7   h  is opened and closed by the intermediate door  33 . 
     The intermediate door  33  is a plate-shaped member disposed along a side surface on the cooling chamber  8  side of the outlet wall  7   b . The intermediate door  33  closes the outlet  7   h  of the outlet wall  7   b  by being disposed at a closed position. In addition, the intermediate door  33  opens the outlet  7   h  of the outlet wall  7   b  by being disposed at an open position. Accordingly, the intermediate door  33  is provided in the conveyance path so as to be switchable between a closed state and an opened state between the heating chamber  7  and the cooling chamber  8 . The intermediate door  33  is provided with a sealing structure including NBR (nitrile rubber) and fluorine-containing rubber, etc., which is a configuration enabled to seal an atmosphere gas and a coolant between the heating chamber  7  and the cooling chamber  8 . The intermediate door  33  is operated to open and close by the intermediate door opening and closing mechanism  34 . 
     In the present embodiment, the intermediate door opening and closing mechanism  34  is formed by using a fluid pressure cylinder, and includes a cylinder  34   a  supported by an upper portion of the frame portion  5   a , and a rod  34   b  projecting from the cylinder  34   a  and joined to the intermediate door  33 . According to a change in projecting amount of the rod  34   b  from the cylinder  34   a , the intermediate door  33  opens and closes. The intermediate door  33  is sandwiched by a pair of front and rear guides  35  provided on one side surface of the cooling chamber  8  side of the outlet wall  7   b  and extending vertically, and displacement of the intermediate door  33  in the up-down direction Z 1  is guided by the guides  35 . In a state where the intermediate door  33  is opened, the workpiece  100  that passed through the heating chamber  7  is conveyed to the inside of the cooling chamber  8  by the intermediate conveyance portion  13 . 
     The intermediate conveyance portion  13  is supported by a lower portion of the frame portion  5   a  of the intermediate door unit  5 , and disposed inside the cooling chamber  8 . This intermediate conveyance portion  13  is, for example, a belt conveyor type conveyance portion. 
     The intermediate conveyance portion  13  includes a drive shaft  36 , a driven shaft  37  disposed on an upstream side of the drive shaft  36  in the conveyance direction A 1 , and a pair of chains  38  and  38  (drive members) that displace the conveyance tray  2  in the conveyance direction A 1  by receiving power from the drive shaft  36 . 
     The driven shaft  37  and the drive shaft  36  extend along the front-rear direction orthogonal to the conveyance direction A 1 . The drive shaft  36  and the driven shaft  37  are respectively supported rotatably by the bottom portion of the frame portion  5   a  via a support member having a bearing, etc. To a pair of end portions of the drive shaft  36  in the front-rear direction Y 1  and a pair of end portions of the driven shaft  37  in the front-rear direction, sprockets are respectively joined rotatably together. Around these pairs of sprockets arranged in the conveyance direction A 1 , chains  38  and  38  are wound. The chains  38  and  38  are disposed away from each other in the front-rear direction Y 1 , which are a configuration enabled to allow the frame portion  2   a  of the conveyance tray  2  to be placed on the chains  38 . The drive shaft  36  is joined to a drive shaft  63  described below (refer to  FIG. 12 ) via a chain  44 , and is driven to rotate in accordance with rotation of the drive shaft  63 . 
     The workpiece  100  conveyed to the inside of the cooling chamber  8  by the intermediate conveyance portion  13  configured as described above is subjected to cooling treatment by the cooling device  6 . 
     Referring to  FIG. 1  and  FIG. 9  to  FIG. 14 , the cooling device  6  includes the cooling chamber  8 , an outlet door unit  41 , a coolant passage defining body  42 , and a vertical displacement mechanism  43 . 
     The cooling chamber  8  is disposed adjacent to the heating chamber  7  to cool the workpiece  100  provided with heat energy in the heating chamber  7 . The cooling chamber  8  is formed into a substantially rectangular parallelepiped box shape vertically long. The cooling chamber  8  includes the inlet wall  8   a , an outlet wall  8   b , a front wall  8   c , a rear wall  8   d , a top wall  8   e , and a bottom wall  8   f.    
     The inlet wall  8   a  is a wall portion disposed to face the intermediate door  33  and extending vertically. In an upper portion of the inlet wall  8   a , the inlet  8   g  is formed, and to this inlet  8   g , the frame portion  5   a  of the intermediate door unit  5  is fixed. According to the configuration described above, the workpiece  100  that passed through the frame portion  5   a  of the intermediate door unit  5  is allowed to advance toward a downstream side of the cooling chamber  8  in the conveyance direction A 1 . 
     In the outlet wall  8   b , an outlet  8   h  to carry the workpiece  100  out of the cooling chamber  8  is formed. The outlet  8   h  is disposed close to an intermediate portion of the outlet wall  8   b  in the up-down direction Z 1 , extends long and narrow from the front wall  8   c  side to the rear wall  8   d  side, and allows the workpiece  100  to pass through. This outlet  8   h  is opened and closed by the outlet door unit  41 . 
     The outlet door unit  41  includes an outlet door  45  and an outlet door opening and closing mechanism  46 . 
     The outlet door  45  is a plate-shaped member disposed along an outer surface of the outlet wall  8   b . The outlet door  45  closes the outlet  8   h  by being disposed at a closed position. In addition, the outlet door  45  opens the outlet  8   h  by being disposed at an open position. The outlet door  45  is provided with a sealing structure including NBR, fluorine-containing rubber, etc., which is a configuration enabled to seal an atmosphere gas and a coolant inside the cooling chamber  8 . The outlet door  45  is operated to open and close by the outlet door opening and closing mechanism  46 . 
     In the present embodiment, the outlet door opening and closing mechanism  46  is formed by using a fluid pressure cylinder, and includes a cylinder  46   a  supported by the cooling chamber  8  on an outer surface of the outlet wall  8   b , and a rod  46   b  projecting from the cylinder  46   a  and joined to the outlet door  45 . According to a change in projecting amount of the rod  46   b  from the cylinder  46   a , the outlet door  45  opens and closes. The outlet door  45  is sandwiched by a pair of front and rear guides  47  provided on the outer surface of the outlet wall  8   b  and extending vertically, and displacement of the outlet door  45  in the up-down direction is guided. In a state where the outlet door  45  is opened, the workpiece  100  that passed through the outlet  8   h  of the cooling chamber  8  is conveyed to the outside of the cooling chamber  8 . 
     From the conveyance tray  2  that passed through the outlet  8   h , the workpiece  100  is taken out. The conveyance tray  2  from which the workpiece  100  was taken out is conveyed to the inlet  7   g  side of the heating chamber  7  of the heating device  4  by a returning mechanism such as a belt conveyor, not shown in the drawings, provided to the first conveyance mechanism  3 . According to the configuration of the first conveyance mechanism  3 , the conveyance tray  2  is conveyed to circulate to the heating device  4  and the cooling device  6 . 
     Inside the cooling chamber  8 , the coolant passage defining body  42  is provided. The coolant passage defining body  42  is a unit to define a coolant passage  48  which supplies a predetermined coolant to the workpiece  100  that passes through the conveyance path B 1  along the conveyance direction A 1 . In the present embodiment, cooling water is used as a coolant, however, oil or the like can be used instead of the cooling water. 
     The coolant passage defining body  42  includes a lower member  49  and an upper member  50  as a plurality of coolant passage defining members, an introduction pipe  51 , and the conveyance tray  2 . The conveyance tray  2  is disposed between the lower member  49  and the upper member  50  as the plurality of coolant passage defining members. That is, in the present embodiment, the conveyance tray  2  has both of a function of conveying the workpiece  100  and a function of defining a portion of the coolant passage  48 . Also the conveyance tray  2  cooperates with the lower member  49  and the upper member  50 , which is configured to define the coolant passage  48 . 
     In the present embodiment, the lower member  49 , the conveyance tray  2 , and the upper member  50  are configured to define the coolant passage  48  in a state of housing the workpiece  100  by being displaced to approach each other along the up-down direction Z 1  (crossing direction) crossing the conveyance direction A 1 , and to allow the workpiece  100  to be let into and out of the coolant passage  48  along the conveyance direction A 1  by being displaced to separate from each other along the up-down direction Z 1 . The coolant passage  48  is provided to supply the coolant to the workpiece  100  inside the cooling chamber  8 , and extends along the up-down direction Z 1  (vertical direction). 
     The lower member  49  is provided as a cylindrical pipe extending upward from the bottom wall  8   f  of the cooling chamber  8 . The lower member  49  is disposed at a substantially center of the cooling chamber  8  in a plan view. An upper end portion of the lower member  49  is disposed near the cooling chamber-side conveyance portion  12 , and is configured to be positioned below the conveyance tray  2 . To the lower member  49 , the introduction pipe  51  is connected. 
     The introduction pipe  51  is provided to introduce the coolant from the outside of the cooling chamber  8  to the lower member  49 . The introduction pipe  51  extends in the front-rear direction Y 1 . One end of the lower member  49  is connected to a lower end portion of the rear wall  8   d . The lower member  49  penetrates through the rear wall  8   d  of the cooling chamber  8 , and the other end of the lower member  49  is connected to a coolant tank not shown in the drawings. According to the configuration described above, the coolant pressure-fed from the coolant tank to the introduction pipe  51  by a pump (not shown) is introduced to the inside of the lower member  49 , and injected upward. A discharge pipe  52  is provided adjacent to the introduction pipe  51 . 
     The discharge pipe  52  is provided to discharge the coolant discharged from the inside to the outside of the coolant passage  48  in the cooling chamber  8 , to the outside of the cooling chamber  8 . The discharge pipe  52  is formed at a lower end portion of the rear wall  8   d  of the cooling chamber  8  at a position adjacent to the introduction pipe  51 , and continued to the inside and the outside of the cooling chamber  8 . The discharge pipe  52  is connected to the coolant tank not shown in the drawings, and a coolant is stored in this coolant tank. Above the lower member  49  adjacent to the discharge pipe  52 , the upper member  50  is disposed. 
     The upper member  50  is provided as a member supported to float inside the cooling chamber  8 . The upper member  50  is provided as a cylindrical pipe extending in the up-down direction Z 1 . At a lower end portion of the upper member  50 , a flange portion  50   a  is provided. This upper member  50  is supported to be displaceable in the up-down direction Z 1  by the vertical displacement mechanism  43 . 
     The vertical displacement mechanism.  43  is provided to support the upper member  50  and a portion (chain unit  66  described below) of the cooling chamber-side conveyance portion  12  in a displaceable manner in the up-down direction Z 1  with respect to the lower member  49 . The vertical displacement mechanism  43  is configured to enable the upper member  50  and the chain unit  66  to move relative to each other in the up-down direction Z 1 . The vertical displacement mechanism  43  is configured to displace the upper member  50  downward to bring the upper member  50  into contact with the conveyance tray  2  when the conveyance tray  2  is disposed at a cooling position P 4 . The vertical displacement mechanism.  43  is supported by the top wall  8   e  of the cooling chamber  8 , and is disposed to extend downward from the top wall  8   e.    
     The vertical displacement mechanism  43  includes a base plate  55 , suspended stays  56  and  56 , a moving up/down mechanism  57 , and guide shafts  58  and  58 . 
     The base plate  55  is formed by using, in the present embodiment, a metal plate. This base plate  55  is disposed at a predetermined distance in the up-down direction Z 1  from the opening at the upper end of the upper member  50 . Accordingly, the coolant that was injected upward inside the upper member  50  can be prevented from being bounced by the base plate  55  and returned to the inside of the coolant passage  48 . To an outer circumferential edge of an upper end of the base plate  55 , the suspended stays  56  and  56  are fixed. 
     The suspended stays  56  and  56  are formed by using, in the present embodiment, metal plates. The suspended stays  56  and  56  are disposed, for example, away from each other in the front-rear direction Y 1 . Upper end portions of the respective suspended stays  56  and  56  are fixed to the base plate  55 . Lower end portions of the respective suspended stays  56  and  56  are fixed to an upper end portion of the upper member  50 . Accordingly, the upper member  50 , the suspended stays  56  and  56 , and the base plate  55  are configured to integrally move as a unit. The unit of these is displaced in the up-down direction Z 1  by the moving up/down mechanism  57 . 
     In the present embodiment, the moving up/down mechanism  57  is formed by using a fluid pressure cylinder, and includes a cylinder  57   a  supported by the top wall  8   e  of the cooling chamber  8 , and a rod  57   b  projecting downward from the cylinder  57   a  and joined to a center of the base plate  55 . The cylinder  57   a  is disposed outside the cooling chamber  8 , and the rod  57   b  extends from a hole portion formed in the top wall  8   e  to the inside of the cooling chamber  8 . 
     According to a change in projecting amount of the rod  57   b  from the cylinder  57   a , the upper member  50 , etc., are displaced in the up-down direction Z 1 . For example, two guide shafts  58  are provided, fixed to the base plate  55 , and supported slidably in the up-down direction Z 1  by guide shaft guide portions  59  formed on the top wall  8   e . This realizes smoother displacement of the rod  57   b.    
     Further, it is configured that the conveyance tray  2  is conveyed from the intermediate conveyance portion  13  to a predetermined conveyance position P 3  by the cooling chamber-side conveyance portion  12 . 
     Referring to  FIG. 12  to  FIG. 14 , the cooling chamber-side conveyance portion  12  is disposed inside the cooling chamber  8 . This cooling chamber-side conveyance portion  12  is a belt conveyor type conveyance portion. 
     The cooling chamber-side conveyance portion  12  includes a cooling chamber-side motor  61  as a drive source disposed outside the cooling chamber  8 , an output transmitting member  62  that transmits an output of the cooling chamber-side motor  61  from the outside of the cooling chamber  8  to the inside of the cooling chamber  8  at a predetermined fixed position, a drive shaft  63  and a driven shaft  64  to be rotated by the output transmitting member  62 , a pair of chains  65  and  65  that are disposed inside the cooling chamber  8 , and displace the conveyance tray  2  in the conveyance direction A 1  by receiving power from the output transmitting member  62 , and a movable joint portion  67  to join a chain unit  66  including the drive shaft  63 , the driven shaft  64 , and the chains  65  and  65  to the upper member  50  in a relatively displaceable manner in the up-down direction Z 1 . 
     The cooling chamber-side motor  61  is, for example, an electric motor. The cooling chamber-side motor  61  is disposed on a downstream side in the conveyance direction A 1  in the cooling chamber  8  at the rear side (outer surface side) of the rear wall  8   d  of the cooling chamber  8 . The housing  61   a  of the cooling chamber-side motor  61  is fixed to a cylindrical motor bracket  68  by using a fixing member such as a bolt. This motor bracket  68  is fixed to the rear wall  8   d  by using a fixing member such as a bolt. 
     Between a portion of the motor bracket  68  facing the rear wall  8   d  and the rear wall  8   d , a sealing member (not shown) is disposed, and as a result, between the housing  61   a  and the rear wall  8   d  are sealed airtightly. To an output shaft (not shown) of the cooling chamber-side motor  61 , one end portion of the output transmitting member  62  is joined rotatably in an interlocking manner. 
     In detail, the output shaft of the cooling chamber-side motor  61  is directed in the up-down direction Z 1 , and the output transmitting member  62  is directed in the front-rear direction Y 1  (horizontal direction). These output shaft and output transmitting member  62  are joined rotatably in an interlocking manner via a mechanism of a gear pair with intersecting axes such as a bevel gear pair. 
     The output transmitting member  62  extends to the inside of the cooling chamber  8  at a position on a downstream side in the conveyance direction A 1  in the cooling chamber  8  through a hole portion  8   i  formed in the rear wall  8   d . The output transmitting member  62  includes one end portion  62   a , a universal joint  62   b , an intermediate shaft  62   c , a universal joint  62   d , and an outer end portion  62   e , and the one end portion  62   a , the universal joint  62   b , the intermediate shaft  62   c , the universal joint  62   d , and the other end portion  62   e  are arranged in this order. Thus, by including the universal joints  62   b  and  62   d , the output transmitting member  62  can change the relative positions of the one end portion  62   a  and the other end portion  62   e . In particular, in the present embodiment, the other end portion  62   e  can be displaced in the up-down direction Z 1  with respect to the one end portion  62   a.    
     To the other end portion  62   e  of the output transmitting member  62 , the drive shaft  63  is joined rotatably together. The drive shaft  63  is disposed on a downstream side of the cooling chamber  8  in the conveyance direction A 1 . The drive shaft  63  extends along the front-rear direction Y 1  orthogonal to the conveyance direction A 1 . Accordingly, an output of the cooling chamber-side motor  61  can be transmitted to the drive shaft  63 . 
     The driven shaft  64  is disposed parallel to the drive shaft  63 . The driven shaft  64  is disposed near the inlet  8   g  of the cooling chamber  8 . Between the drive shaft  63  and the driven shaft  64 , the lower member  49  is disposed. To a pair of end portions of the drive shaft  63  in the front-rear direction Y 1  and a pair of end portions of the driven shaft  64  in the front-rear direction Y 1 , sprockets are respectively joined rotatably together. Around pairs of sprockets arranged in the conveyance direction A 1 , chains  65  and  65  are wound. The chains  65  and  65  are disposed away from each other in the front-rear direction Y 1 , which are a configuration enabled to allow the frame portion  2   a  of the conveyance tray  2  to be placed on. Between the chains  65  and  65 , an upper end portion of the lower member  49  is disposed. Thus, the upper end portion of the lower member  49  is surrounded by the drive shaft  63 , the driven shaft  64 , and the pair of chains  65  and  65 . 
     In the present embodiment, in the front-rear direction Y 1 , a distance between the chains  65  and  65  is set to be equal to or longer than an entire length of the workpiece  100 . With the configuration described above, in accordance with driving of the cooling chamber-side motor  61 , the output transmitting member  62  rotates, and this rotation is transmitted to the drive shaft  63 . Then, this drive shaft  63  drives the chains  65  and  65  and rotates the driven shaft  64 . That is, by driving the cooling chamber-side motor  61 , the pair of chains  65  and  65  rotate. Accordingly, the conveyance tray  2  on the pair of chains  65  and  65  moves in the conveyance direction A 1 . 
     As described above, the drive shaft  63 , the driven shaft  64 , and the pair of chains  65  and  65  described above constitute the chain unit  66 . This chain unit  66  is supported to be displaceable in the up-down direction Z 1  by the movable joint portion  67 . The chain unit  66  is configured to be capable of being joined to the vertical displacement mechanism  43  via the movable joint portion  67  and the upper member  50 , and capable of being displaced to the conveyance position P 3  and the cooling position P 4 . 
     The chain unit  66  at the conveyance position P 3  supports the conveyance tray  2  so that the conveyance tray  2  is away from the upper member  50  and the lower member  49 , and, the chain unit  66  at the cooling position P 4  disposes the conveyance tray  2  so that the conveyance tray  2  comes into contact with the lower member  49 . 
     The movable joint portion  67  includes a pair of beam portions  69  and  70 , a plurality of brackets  71 , and a plurality of guide receiving portions  72 . 
     The pair of beam portions  69  and  70  are provided as beam-shaped portions extending along the conveyance direction A 1 . One beam portion  69  is disposed parallel to the chain  65  at the rear side (rear wall  8   d  side) of the chain  65 , and supports one end portion of the drive shaft  63  and one end portion of the driven shaft  64  rotatably. The other beam portion  70  is disposed parallel to the chain  65  at the front side (front wall  8   c  side) of the chain  65 , and supports the other end portion of the drive shaft  63  and the other end portion of the driven shaft  64  rotatably. 
     The pair of beam portions  69  and  70  are fixed to the plurality of brackets  71 . The plurality of brackets  71  are provided to join the pair of beam portions  69  and  70  to the upper member  50 . Each bracket  71  is formed into, for example, an L shape. The brackets  71  and  71  are fixed to both end portions in the conveyance direction A 1  of one beam portion  69 , and both ends of the one beam portion  69  are supported. To both end portions in the conveyance direction A 1  of the other beam portion  70 , the brackets  71  and  71  are fixed, and both ends of the other beam portion  70  are supported. 
     A lower end portion of each bracket  71  is fixed to a corresponding beam portion  69  or  70 . In each bracket  71 , a lower surface  71   a  of a portion extending horizontally is received by an upper surface of the flange portion  50   a  of the upper member  50 . The brackets  71  can be displaced upward with respect to the flange portion  50   a.    
     To lower end portions of the respective beam portions  69  and  70 , guide receiving portions  72  are fixed. The guide receiving portions  72  are disposed at, for example, a plurality of positions (in the present embodiment, two positions) on each of the beam portions  69  and  70  in the conveyance direction A 1 . In each guide receiving portion  72 , a guide hole portion  72   a  extending vertically is formed. In addition, a guide shaft  73  that can be fit in this guide hole portion  72   a  is provided. 
     The guide shaft  73  is provided for each guide hole portion  72   a , and fixed to a corresponding one of lower portion stays  74  and  74 . The lower portion stays  74  and  74  are fixed to the front wall  8   c  or the rear wall  8   d . Each guide shaft  73  is fit in a corresponding guide hole portion  72   a  vertically slidably. Accordingly, movements of the pair of beam portions  69  and  70  in the up-down direction Z 1  are guided. 
     To each of the lower portion stays  74  and  74 , a stopper  75  is fixed. The stopper  75  is formed by using, for example, a bolt, and screw-coupled to a corresponding one of the lower portion stays  74  and  74 . Accordingly, the position of the stopper  75  in the up-down direction Z 1  can be adjusted. 
     Referring to  FIG. 13  and  FIG. 15 , the stopper  75  on the rear wall  8   d  side faces a lower end portion of the beam portion  69  on the rear wall  8   d  side in the up-down direction Z 1 . On the other hand, the stopper  75  on the front wall  8   c  side faces a lower end portion of the beam portion  70  on the front wall  8   c  side in the up-down direction Z 1 . When the pair of beam portions  69  and  70  reach the predetermined cooling position P 4 , each of the beam portions  69  and  70  is received by a corresponding stopper  75 , and is restrained from further moving downward. 
     On the front wall  8   c  and the rear wall  8   d , upper portion stays  76  and  76  are respectively provided. To each of the upper portion stays  76  and  76 , a stopper  77  is fixed. The stopper  77  is formed by using, for example, a bolt, and screw-coupled to a corresponding one of the upper portion stays  76  and  76 . Accordingly, the position of the stopper  77  in the up-down direction Z 1  can be adjusted. 
     The stopper  77  on the rear wall  8   d  side faces the bracket  71  of the beam portion  69  on the rear wall  8   d  side in the up-down direction Z 1 . On the other hand, the stopper  77  on the front wall  8   c  side faces the bracket  71  of the beam portion  70  on the front wall  8   c  side in the up-down direction Z 1 . When the pair of beam portions  69  and  70  reach the predetermined conveyance position P 3 , each bracket  71  is received by a corresponding stopper  77 , and the pair of beam portions  69  and  70  are restrained from further moving upward. 
     With the configuration described above, when the upper member  50  lifts each bracket  71 , the upper member  50  and the chain unit  66  are capable of being integrally displaced in the up-down direction Z 1 . When the upper member  50  is positioned at the conveyance position P 3 , the upper member  50  lifts the pair of beam portions  69  ad  70 . In this state, the cooling chamber-side conveyance portion  12  receives the conveyance tray  2  from the intermediate conveyance portion  13  and conveys the conveyance tray  2  by operation of the chains  65  and  65 . Then, the power transmitting member  62  is rotated by driving of the cooling chamber-side motor  61 , and the drive shaft  63  accordingly rotates, and as a result, the chains  65  and  65  rotate. 
     When the conveyance tray  2  reaches the predetermined conveyance position P 3 , the chains  65  stop, and the conveyance tray  2  stops at the conveyance position P 3 . At this time, by operating the moving up/down mechanism  57  of the vertical displacement mechanism  43 , the cylinder  57   b  is displaced downward. Accordingly, the upper member  50 , the pair of beam portions  69  and  70 , and the chain unit  66  are displaced downward. Then, as shown in  FIG. 15  and  FIG. 16 , the pair of beam portions  69  and  70  are received by the lower stopper  75 , and accordingly, the chain unit  66  is held at the cooling position P 4 . At this time, the rim portion of the hole portion  2   c  of the conveyance tray  2  is received by the upper end portion  49   a  of the lower member  49 . 
     Then, when the rod  57   b  of the moving up/down mechanism  57  is further displaced downward, contact of the upper member  50  with the bracket  71  is released, and the lower end portion of the upper member  50  presses the conveyance tray  2  downward. Note that, in a groove formed on a lower surface of the flange portion  49   a  of the lower member  49 , a sealing member such as an O-ring is disposed, and in a groove formed on an upper surface of the flange portion  50   a  of the upper member  50 , a sealing member such as an O-ring is disposed. 
     Then, the conveyance tray  2  becomes sandwiched between the lower member  49  and the upper member  50 , and the sealing members described above liquid-tightly seal the portions between the conveyance tray  2  and the upper member  50  and between the conveyance tray  2  and the lower member  49 . Then, a coolant passage  48  is defined by the lower member  49 , the conveyance tray  2 , and the upper member  50 . Thus, with the configuration in which the upper member  50  and the lower member  49  are brought into contact with the conveyance tray  2  from above and below, a stroke (vertical movement amount) of the upper member  50  can be reduced, so that the heat treatment apparatus  1  can be made more compact. 
     Referring to  FIG. 14  to  FIG. 16 , the coolant passage  48  is a passage extending along the up-down direction Z 1 . This coolant passage  48  is defined by an inner circumferential surface of the introduction pipe  51 , an inner circumferential surface of the lower member  49 , an inner circumferential surface of the hole portion  2   c  of the conveyance tray  2 , and an inner circumferential surface of the upper member  50 , and is opened upward inside the cooling chamber  8 . Inside the coolant passage  48 , the workpiece  100  is surrounded by the upper member  50 . Inside the coolant passage  48 , a coolant flows from the lower side to the upper side toward the workpiece  100  supported by the support portions  2   b  of the conveyance tray  2 . 
     Then, the workpiece  100  supported by the conveyance tray  2  is soaked in the coolant, and is cooled by the coolant. At this time, the support portions  2   b  of the conveyance tray  2  function as rectifying members to rectify the coolant in the coolant passage  48 . This coolant reaches an upper end of the coolant passage  48  (an upper end of the upper member  50 ), and then reaches the outside of the coolant passage  48  and falls toward the bottom wall  8   f  of the cooling chamber  8 . The coolant that fell onto the bottom wall  8   f  passes through the discharge pipe  52  attached to the rear wall  8   d , and is returned to the coolant tank (not shown) outside the cooling chamber  8 . 
     A flow volume, a flow rate, and a supply timing of the coolant to the coolant passage  48  are controlled by operation of a pump provided in a coolant storage tank (not shown). This enables, for example, uniform extinguishment of a vapor film on the workpiece  100  and cooling of the workpiece  100  without being pearlite and bainite nose. Uniform cooling while reducing the flow rate enables control of martensitic transformation timing. As a result, low-distortion treatment is enabled, and variation in heat deformation amount of the workpiece  100  can be reduced. 
     After cooling treatment is completed, the rod  57   b  of the moving up/down mechanism  57  of the vertical displacement mechanism  43  is displaced upward as shown in  FIG. 12  to FIG.  15 . Accordingly, the upper member  50  is displaced upward, and when the bracket  71  comes into contact with the flange portion  50   a  of the upper member  50 , the bracket  71  and the chain unit  66  are displaced upward. Then, when the bracket  71  comes into contact with the stopper  77 , operation of the moving up/down mechanism  57  stops. 
     Accordingly, the conveyance tray  2  is displaced upward together with the chain unit  66  and returned to the conveyance position P 3 . At this time, due to upward displacement of the upper member  50  with respect to the conveyance tray  2 , the coolant inside the upper member  50  instantly falls to the outside of the upper member  50 . Accordingly, the workpiece  100  surrounded by the upper member  50  can be quickly taken out from the coolant. Therefore, for example, marquenching that is effective for low-distortion treatment can also be easily performed. 
     Next, according to driving of the cooling chamber-side motor  61 , the chains  65  and  65  of the chain unit  66  rotate, and the conveyance tray  2  moves to the outlet door  45  side. Then, the outlet door  45  is opened, and accordingly, the conveyance tray  2  and the workpiece  100  are carried out of the cooling chamber  8 . 
     As described above, in the heat treatment apparatus  1 , the workpiece  100  is supported by the conveyance tray  2 , and this conveyance tray  2  is conveyed in the conveyance path B 1  by the first conveyance mechanism  3 . Accordingly, the first conveyance mechanism  3  conveys the workpiece  100  not directly but via the conveyance tray  2 . Therefore, the first conveyance mechanism  3  can convey the conveyance tray  2  in a stable posture without being influenced by the shape of the workpiece  100 . As a result, the workpiece  100  is conveyed in a more stable posture. In addition, by a simple configuration using the conveyance tray  2  for conveyance of the workpiece  100 , the workpiece  100  is conveyed in a stable posture. Thus, by the simple configuration, the heat treatment apparatus  1  capable of more reliably conveying the workpiece  100  along the desired conveyance path B 1  can be realized. 
     In addition, in the heat treatment apparatus  1 , the second conveyance mechanism  18  to move the workpiece  100  between the conveyance tray  2  and the heating member  17  in the heating chamber  7  is provided. With this configuration, the workpiece  100  can be heated by the heating member  17 . At the time of this heating, the workpiece  100  is away from the conveyance tray  2 . Therefore, the conveyance tray  2  is prevented from being heated by the heating member  17  and the workpiece  100 . Accordingly, defects of the conveyance tray  2  caused by heat distortion can be more reliably suppressed. Therefore, the life of the conveyance tray  2  (the number of times of reuse of the conveyance tray  2 ) can be improved. Further, a conveyance tray  2  that does not need to be heated can be prevented from being heated, so that through improvement in energy efficiency, energy for the heat treatment apparatus  1  can be further saved. 
     In the heat treatment apparatus  1 , the heating member is disposed above the conveyance path B 1 . With this configuration, since the heating member  17  is disposed away from the conveyance path B 1 , the heat treatment apparatus  1  can be prevented from becoming long in the conveyance direction A 1 . In addition, since the heating member  17  is disposed above the conveyance path B 1 , heat from the heating member  17  is transferred to a portion above the heating member  17 , and is prevented from being transferred to the conveyance path B 1  side. Accordingly, the conveyance tray  2  can be more reliably prevented from being heated. 
     In the heat treatment apparatus  1 , the second conveyance mechanism  18  includes a support portion  18   a  to lift the workpiece  100  through the hole portion  2   c  formed in the conveyance tray  2  in the heating chamber  7 . With this configuration, by a simple operation of upward displacement with respect to the conveyance tray  2 , the support portion  18   a  of the second conveyance mechanism  18  can lift the workpiece  100 . Therefore, the configuration of the second conveyance mechanism  18  can be made simpler. 
     In addition, in the heat treatment apparatus  1 , the coolant passage  48  extends along the up-down direction Z 1  (vertical direction). With this configuration, since the cooling chamber  8  can be formed to be vertically long, the size of the heat treatment apparatus  1  in the horizontal direction can be reduced. The extending direction of the coolant passage  48  and the conveyance direction A 1  are orthogonal to each other, so that the heat treatment apparatus  1  can be prevented from becoming excessively large in each of the horizontal direction and the vertical direction. Therefore, the heat treatment apparatus  1  can be made more compact. 
     In the heat treatment apparatus  1 , the space between the heating chamber  7  and the cooling chamber  8  can be closed by the intermediate door  33 . Accordingly, the atmosphere in the heating chamber  7  can be made more stable. In addition, a coolant inside the cooling chamber  8  can be more reliably prevented from flying into the heating chamber  7 . 
     In the heat treatment apparatus  1 , the first conveyance mechanism  3  is configured to circulate the conveyance tray  2  between the outside of the heating chamber  7 , the heating chamber  7 , the cooling chamber  8 , and the outside of the cooling chamber  8 . With this configuration, the conveyance tray  2  can be repeatedly used for conveyance of the workpiece  100  in the heat treatment apparatus  1 . Therefore, the number of conveyance trays  2  necessary for heat treatment of a large number of workpieces  100  in the heat treatment apparatus  1  can be reduced. A possible number of times of reuse of the conveyance tray  2  is significantly increased by preventing the conveyance tray  2  from being heated. 
     In the heat treatment apparatus  1 , since the heating chamber-side motor  22  of the first conveyance mechanism  3  is disposed outside the heating chamber  7 , the heating chamber  7  can be made more compact. In addition, the output transmitting member  23  is configured so as not to move from a fixed position. Therefore, a portion that needs to be sealed between the inside and the outside of the heating chamber  7 , that is, the portion between the output transmitting member  23  and the heating chamber  7  can be made smaller. Accordingly, the first conveyance mechanism  3  can be realized by a simple configuration. 
     In the heat treatment apparatus  1 , the extending direction of the coolant passage  48  (up-down direction Z 1 ) and the conveyance direction A 1  of the workpiece  100  are different from each other. Accordingly, the shape of the heat treatment apparatus  1  can be prevented from becoming excessively long in any of the extending direction of the coolant passage  48  and the conveyance direction A 1 . Therefore, the heat treatment apparatus  1  can be made more compact. In addition, by displacing the upper member  50  and the lower member  49  as a plurality of coolant passage defining members relative to each other so as to separate from each other in the up-down direction Z 1 , the workpiece  100  can be let into and out of the coolant passage  48 . Therefore, it is not necessary to provide a robot arm, etc., to let the workpiece  100  into and out of the coolant passage  48 . Accordingly, the heat treatment apparatus  1  can be made more compact. 
     In addition, the heat treatment apparatus  1  is configured so that a cooling liquid as a coolant flows upward from the lower side in the coolant passage  48 . With this configuration, the coolant passage defining body  42  can be formed to be vertically long, so that the size of the heat treatment apparatus  1  in the horizontal direction can be made smaller. In addition, the extending direction of the coolant passage  48  and the conveyance direction A 1  are orthogonal to each other, so that the heat treatment apparatus  1  can be prevented from becoming excessively large in size in each of the horizontal direction and the vertical direction. Therefore, the heat treatment apparatus  1  can be made more compact. Further, in the coolant passage  48 , a coolant flows upward from the lower side, so that the coolant can be more uniformly moved upward. Accordingly, the workpiece  100  can be more uniformly cooled. 
     In the heat treatment apparatus  1 , the conveyance tray  2  defines a part of the coolant passage  48 . Therefore, an exclusive member to support the conveyance tray  2  inside the coolant passage  48  is unnecessary, and the heat treatment apparatus  1  can be configured to be more compact and simpler. 
     In the heat treatment apparatus  1 , the workpiece  100  is disposed at an intermediate portion of the coolant passage  48 . To this workpiece  100 , a coolant is supplied through the hole portion  2   c  of the conveyance tray  2 . Accordingly, the workpiece  100  can be more reliably cooled by the coolant while being reliably supported inside the coolant passage  48 . 
     In the heat treatment apparatus  1 , by displacing the upper member  50  to the lower member  49  side by the vertical displacement mechanism  43 , the coolant passage  48  is formed. In addition, by moving up the upper member  50  away from the lower member  49  by the vertical displacement mechanism  43 , the workpiece  100  can be exposed from the coolant passage defining body  42 . This enables letting-in and letting-out of the workpiece  100  along the conveyance direction A 1 . 
     In the heat treatment apparatus  1 , the chain unit of the first conveyance mechanism  3  supports, at the conveyance position P 3 , the conveyance tray  2  so that the conveyance tray  2  is away from the upper member  50  and the lower member  49 , and at the cooling position P 4 , disposes the conveyance tray  2  so that the conveyance tray  2  comes into contact with the lower member  49 . With this configuration, when the chain unit  66  is disposed at the conveyance position P 3 , the chain unit  66  can support the conveyance tray  2  in a state where this conveyance tray  2  does not collide with other members. Accordingly, the conveyance tray  2  can be smoothly conveyed. On the other hand, when the chain unit  66  is disposed at the cooling position P 4 , the conveyance tray  2  can be disposed so that this conveyance tray  2  defines a coolant passage  48  in cooperation with the lower member  49 . Thus, the vertical displacement mechanism  43  not only simply displaces the upper member  50  vertically with respect to the lower member  49 , but also displaces the chain unit  66  and the conveyance tray  2  vertically. 
     In the heat treatment apparatus  1 , the vertical displacement mechanism  43  is configured to displace the upper member  50  to bring the upper member  50  into contact with the conveyance tray  2  when the conveyance tray  2  is at the cooling position P 4 . With this configuration, by displacing the upper member  50  downward by the vertical displacement mechanism  43 , the upper member  50  and the lower member  49  can be made to sandwich the conveyance tray  2 . As a result, the coolant passage  48  can be defined by cooperation of the upper member  50 , the conveyance tray  2 , and the lower member  49 . 
     In the heat treatment apparatus  1 , the support portions  2   b  of the conveyance tray  2  function as rectifying members to rectify a coolant inside the coolant passage  48 . With this configuration, a larger amount of coolant can be brought into uniform contact with the workpiece  100  per unit time, so that distortion of the workpiece  100  can be suppressed. 
     Referring to  FIG. 17  as a schematic configuration diagram of the heat treatment apparatus  1  to describe the effects of the heat treatment apparatus  1 , the coolant passage  48  is disposed across the first conveyance mechanism  3  vertically. In addition, vertically extending disposition of the coolant passage  48  is adopted, and disposition of the heating member  17  and the second conveyance mechanism  18  arranged one above the other is adopted. With this configuration, in the heat treatment apparatus  1 , a layout compact in the up-down direction Z 1  as well can be realized. 
     An embodiment of the present invention is described above, however, the present invention is not limited to the embodiment described above. The present invention can be variously modified within the scope of the claims. 
     For example, inside the coolant passage  48 , a rectifying member such as a fin or a rectifying duct to rectify a coolant may be fixed. Accordingly, a coolant flowing direction around the workpiece  100  can be further uniformized. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be widely applied as a heat treatment apparatus. 
     REFERENCE SIGNS LIST 
     
         
           1 : Heat treatment apparatus 
           2 : Conveyance tray 
           2   b : Support portion to support workpiece (rectifying member) 
           2   c : Hole portion to make coolant pass through 
           3 : First conveyance mechanism (conveyance mechanism) 
           42 : Coolant passage defining body 
           43 : Vertical displacement mechanism 
           48 : Coolant passage 
           49 : Lower member (coolant passage defining member) 
           50 : Upper member (coolant passage defining member) 
           66 : Chain unit (unit) 
           100 : Workpiece 
         A 1 : Conveyance direction 
         B 1 : Conveyance path 
         Z 1 : Up-down direction (crossing direction)