Patent Publication Number: US-2012028202-A1

Title: Heat treatment device and heat treatment method

Description:
TECHNICAL FIELD 
     The present invention relates to a heat treatment device and a heat treatment method, for example, to a heat treatment device preferably used for treatments such as hardening of a treatment object. Priority is claimed on Japanese Patent Application No. 2009-095892, filed on Apr. 10, 2009, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     In heat treatment devices that perform treatments such as hardening by heating and cooling metal materials as treatment objects, cooling apparatuses using an oil cooling system or cooling apparatuses using a gas cooling system are conventionally used in the case where cooling at high speeds is required. In the cooling apparatuses using the oil cooling system, cooling efficiency is excellent. However, it is almost impossible to perform fine cooling control, resulting in a problem in that heat-treatment products are likely to be deformed. On the other hand, in the cooling apparatuses using the gas cooling system, cooling control is easily performed through control of flow rate of a gas or the like. Therefore, despite its excellence in resistance to deformation of heat-treatment products, a problem of low cooling efficiency is posed. 
     To address this, Patent Document 1 discloses a technique in which a nozzle for liquid and a nozzle for gas are arranged around a heat-treatment product. A coolant is sprayed from the nozzle for liquid (a mist cooling), and a cooling gas is supplied from the nozzle for gas, to thereby make it possible to improve cooling controllability and cooling efficiency. 
     BACKGROUND ART LITERATURE 
     Patent Literature 
     
         
         Patent Document 1: Japanese Unexamined Patent Application, First Publication No. H11-153386 
       
    
     DISCLOSURE OF INVENTION 
     Problems that the Invention is to Solve 
     However, the aforementioned prior art has the following problems. 
     If there is distribution of mist density in the cooling chamber, there may be a difference in cooling characteristics, leading to temperature distribution in the treatment object. Furthermore, if a plurality of treatment objects is treated, there is a possibility of an occurrence of temperature difference among the treatment object in accordance with distribution of the mist density. 
     If the treatment object has non-uniform temperature distribution as described above, this may be a cause of its deformation. Furthermore, if the treatment object with non-uniform temperature distribution is subjected to a hardening treatment, there is a possibility that the treatment object will not have uniform hardness. 
     On the other hand, if there is a temperature difference among treatment objects, there is a possibility of difference in quality among the treatment objects, resulting in poor quality. 
     The present invention has been achieved in view of the aforementioned points, and has an object to provide a heat treatment device and a heat treatment method that are capable of suppressing non-uniform temperature distribution in cooling treatment. 
     Means for Solving the Problems 
     To solve the above problems, the present invention adopts the following. 
     The present invention is a heat treatment device including a cooling chamber for cooling a heated treatment object, further including: a mist supply portion for supplying a coolant in mist form into the cooling chamber; and an adjustment portion for supplying a gas into the cooling chamber to adjust a flow direction of the coolant in mist form. 
     In the heat treatment device with the above construction, the coolant in mist form is supplied into the cooling chamber. In addition, the gas is supplied into the cooling chamber. The flow direction of the coolant in mist form is adjusted by the flow of the supplied gas so as to move toward the treatment object. Therefore, it is possible to attach the coolant even to the surface of the treatment object to which it is difficult to attach the coolant due to low mist density. 
     In the heat treatment device of the present invention, the adjustment portion may supply the gas in multiple directions. 
     In the heat treatment device with the above construction, even if there are a plurality of surfaces of the treatment objects in which have a small amount of coolant is attached, it is possible to attach a coolant to the surfaces. 
     In the heat treatment device of the present invention, the adjustment portion may include a modification portion for modifying a supply direction of the gas. 
     In the heat treatment device with the above construction, the flow direction of the coolant in mist form in the cooling chamber changes as the supply direction of the gas which is modified by the operation of the modification portion. 
     The heat treatment device of the present invention may further include a transfer portion for transferring the treatment object in a predetermined direction. The adjustment portion may include: pipe bodies which extend along a transfer direction of the transfer portion and into which the gas is introduced; and a plurality of nozzle portions provided in the pipe bodies in a manner spaced from each other in the transfer direction. The modification portion may include on-off valves each provided correspondingly to each of the pipe bodies. 
     In the heat treatment device with the above construction, the flow direction of the coolant in mist form in the cooling chamber changes as the supply direction of the gas which is modified by the operations of the on-off valves is modified. Furthermore, nozzle portions for supplying the gas are provided in a manner spaced from each other along the transfer direction of the treatment object. Therefore, the directions of flow of the coolant in mist form are adjusted so as to be substantially uniform with respect to the transfer direction. 
     The heat treatment device of the present invention may further include a control portion for controlling the modification portion so as to modify the supply direction of the gas after passage of a predetermined period of time. 
     In the heat treatment device with the above construction, the supply direction of the gas is modified after passage of a predetermined period of time. Therefore, after the directions of flow of the coolant in mist form being stable in a predetermined direction, the supply direction of the gas changes to another direction. As a result, it is possible to attach an amount of coolant sufficient for cooling to a predetermined surface of the treatment object. 
     The heat treatment device of the present invention may further include a control portion for controlling the modification portion so as to modify the supply direction of the gas before passage of a predetermined period of time. 
     In the heat treatment device with the above construction, the supply direction of the gas is modified before passage of a predetermined period of time. Therefore, the flow of the coolant in mist form in the cooling chamber does not become stable but becomes a turbulent flow. As a result, even in the case where surfaces of the treatment object have a complex shape or a plurality of treatment objects are cooled simultaneously, the coolant in mist form moves as a turbulent flow, to thereby make it possible to attach the coolant to any surface of the treatment object. 
     The heat treatment device of the present invention may further include: a temperature measurement portion for measuring a temperature of the treatment object; and a second control portion for controlling the modification portion based on a measurement result from the temperature measurement portion. 
     In the heat treatment device with the above construction, the supply direction of the gas is modified through control of the modification portion by the second control portion based on the measurement result from the temperature measurement portion. Furthermore, as to this modification, the flow direction of the coolant in mist form in the cooling chamber changes. 
     In the heat treatment device of the present invention, the temperature measurement portion may measure a temperature of the treatment object at multiple sites. Furthermore, the second control portion may control the modification portion based on a difference in measured temperatures among the sites. 
     In the heat treatment device with the above construction, the supply direction of the gas is modified through control of the modification portion by the second control portion based on a difference in measured temperatures among the sites. Therefore, it is possible to attach the coolant more preferentially to, for example, a higher-temperature surface of the treatment object. 
     In the heat treatment device of the present invention, the temperature measurement portion may measure temperature of each of the treatment objects. Furthermore, the second control portion may control the modification portion based on a difference in measured temperatures among the treatment objects. 
     In the heat treatment device with the above construction, the supply direction of the gas is modified through control of the modification portion by the second control portion based on a difference in temperature among the treatment objects. Therefore, it is possible to attach the coolant more preferentially to, for example, a predetermined treatment object at a higher temperature. 
     In the heat treatment device of the present invention, the gas may be a pressure adjusting gas for adjusting a pressure in the cooling chamber. 
     In the heat treatment device with the above construction, the flow of the coolant in mist form is directed toward the treatment object by the flow of the supplied pressure supply gas. 
     In the heat treatment device of the present invention, the gas may be a cooling gas for cooling the treatment object. 
     In the heat treatment device with the above construction, the flow direction of the coolant in mist form is directed toward the treatment object by the flow of the supplied cooling gas. 
     A heat treatment method of the present invention, including: a cooling step of cooling a heated treatment object by supplying a coolant in mist form into a cooling chamber; and an adjustment step of adjusting a flow direction of the coolant in mist form by supplying a gas into the cooling chamber. 
     In the above method, the coolant in mist form is supplied into the cooling chamber. In addition, the gas is supplied into the cooling chamber. The flow direction of the coolant in mist form is adjusted in the above adjustment step by the flow of the supplied gas so as to move toward the treatment object. Therefore, it is possible to attach the coolant even to the surface of the treatment object to which it is difficult to attach the coolant due to low mist density. 
     In the heat treatment method of the present invention, the gas may be supplied in a plurality of directions. 
     In the above method, even if there are a plurality of surfaces of the treatment object in which a small amount of coolant is attached, it is possible to attach a coolant to the surfaces. 
     The heat treatment method of the present invention may further include a step of modifying a supply direction of the gas. 
     In the above method, the flow direction of the coolant in mist form in the cooling chamber changes as to a modification of the supply direction of the gas. 
     The heat treatment method of the present invention may further include a step of transferring the treatment object in a predetermined direction. Furthermore, the gas may be introduced into a plurality of pipe bodies and is also supplied into the cooling chamber from a plurality of nozzle portions, the pipe bodies extending along a transfer direction of the treatment object, and the nozzle portions being provided in the pipe bodies in a manner spaced from each other along the transfer direction. Furthermore, the supply direction of the gas may be modified by operations of on-off valves each of which is provided correspondingly to each of the pipe bodies. 
     In the above method, the flow direction of the coolant in mist form in the cooling chamber changes as to a modification of the supply direction of the gas by the operations of the on-off valves. Furthermore, a plurality of nozzle portions for supplying the gas are provided in a manner spaced from each other along the transfer direction of the treatment object. Therefore, the directions of flow of the coolant in mist form are adjusted so as to be substantially uniform with respect to the transfer direction. 
     In the heat treatment method of the present invention, the supply direction of the gas may be modified after passage of a predetermined period of time. 
     In the above method, the supply direction of the gas is modified after passage of a predetermined period of time. Therefore, after the flow direction of the coolant in mist form in the cooling chamber becomes stable in a predetermined direction, the supply direction of the gas changes to another direction. As a result, it is possible to attach an amount of coolant sufficient for cooling to a predetermined surface of the treatment object. 
     In the heat treatment method of the present invention, the supply direction of the gas may be modified before passage of a predetermined period of time. 
     In the above method, the supply direction of the gas is modified before passage of a predetermined period of time. Therefore, the flow of the coolant in mist form in the cooling chamber does not become stable and becomes a turbulent flow. As a result, even in the case where surfaces of the treatment object have a complex shape or a plurality of treatment objects are cooled simultaneously, the coolant in mist form flows as a turbulent flow, to thereby make it possible to attach the coolant to any surface of the treatment object. 
     The heat treatment method of the present invention may further include a measurement step of measuring the temperature of the treatment object. Furthermore, the supply direction of the gas may be changed based on temperature measured in the measurement step. 
     In the above method, the supply direction of the gas is modified based on the measurement result in the measurement step. Furthermore, as to this modification, the flow direction of the coolant in mist form in the cooling chamber. 
     In the heat treatment method of the present invention, temperature of the treatment object may be measured at a plurality of sites in the measurement step, and the supply direction of the gas may be modified based on a difference in measured temperatures among the sites of the treatment object. 
     In the above method, the supply direction of the gas is modified based on a difference in measured temperatures among the sites of the treatment object. Therefore, it is possible to attach the coolant more preferentially to, for example, a higher-temperature surface of the treatment object. 
     In the heat treatment method of the present invention, temperatures of a plurality of the treatment objects may be measured in the measurement step, and the supply direction of the gas may be modified based on a difference in measured temperatures among the plurality of treatment objects. 
     In the above method, the supply direction of the gas is modified based on a difference in temperature among the plurality of treatment objects. Therefore, it is possible to attach the coolant more preferentially to, for example, a predetermined treatment object at a higher temperature. 
     In the heat treatment method of the present invention, a pressure adjusting gas for adjusting a pressure in the cooling chamber may be used as the gas. 
     In the above method, the direction of the flow of the coolant in mist form is adjusted to be directed toward the treatment object by the flow of the supplied pressure supply gas. 
     In the heat treatment method of the present invention, a cooling gas for cooling the treatment object may be used as the gas. 
     In the above method, the flow direction of the coolant in mist form is adjusted to be directed toward the treatment object by the flow of the supplied cooling gas. 
     Effects of the Invention 
     According to the present invention, it is possible to attach a sufficient amount of coolant to a surface of a treatment object on which an amount of attached coolant is small due to a low mist density. Consequently, according to the present invention, it is possible to substantially uniformly cool the surfaces of the treatment object. Therefore, according to the present invention, it is possible to suppress non-uniform temperature distribution in the treatment object when it is cooled, to suppress variation and the like in deformation and hardness, and to avoid an occurrence of poor quality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a whole construction view of a vacuum heat-treating furnace. 
         FIG. 2  is a front cross-sectional view showing a cooling chamber according to a first embodiment. 
         FIG. 3  is a front cross-sectional view showing a cooling chamber according to a second embodiment. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereunder is a description of embodiments of a heat treatment device and a heat treatment method according to the present invention with reference to  FIG. 1  to  FIG. 3 . In the drawings used for the following description, the scale of each component has been suitably altered in order to make each component a recognizable size. 
     Furthermore, in the embodiments, an example of two-chamber-type vacuum heat-treating furnace (hereinafter, simply referred to as “vacuum heat-treating furnace”) will be illustrated as a heat treatment device. 
     First Embodiment 
       FIG. 1  is a whole construction view of a vacuum heat-treating furnace  100  according to the present embodiment. 
     The vacuum heat-treating furnace (heat treatment device)  100  is an apparatus that subjects a treatment object M to heating treatments such as hardening or the like, in which a heating chamber  110  and a cooling chamber  120  are arranged adjacent to each other. A partition wall  130  is provided between the heating chamber  110  and the cooling chamber  120 . When the partition wall  130  is opened, the treatment object M is moved from the heating chamber  110  to the cooling chamber  120 , and is then cooled in the cooling chamber  120 . 
     The treatment object M is subjected to heat treatments, one by one, by the vacuum heat-treating furnace  100 . The treatment object M is made from a metal material (inclusive of an alloy), such as steel or the like, containing a predetermined amount of carbon. The treatment object M is formed in a substantially rectangular parallelepiped shape. 
     The present invention is characterized by a cooling treatment in the cooling chamber  120 . Therefore, the cooling chamber  120  will be described in detail below. 
       FIG. 2  is a front cross-sectional view of the cooling chamber  120  according to the present embodiment. Hereinafter, the right side in  FIG. 2  is referred to simply as “the right side” (the same applies to the left side), and the up side in  FIG. 2  is referred to simply as “the up side” (the same applies to the down side). 
     The cooling chamber  120  has a substantially cylindrical vacuum container  1  that forms outer shell of the cooling chamber  120 . Furthermore, in the cooling chamber  120 , there are provided: a transfer portion  10 ; a mist supply portion  20 ; a gas supply portion (adjustment portion)  30 ; a temperature measurement portion  40 ; and a control portion (control portion, second control portion)  50 . 
     The transfer portion  10  is a member for transferring the treatment object M in a predetermined direction along the horizontal direction. The transfer portion  10  includes: a pair of support frames  11 ; a plurality of rollers  12 ; and second support frames  13 . The pair of support frames  11  are arranged in an opposed manner with a space therebetween, and extend in the transfer direction of the treatment object M. The plurality of rollers  12  are provided rotatably on each of the opposed surfaces of the support frames  11 . On each opposed surface of the support frames  11 , the rollers  12  are spaced from each other by a predetermined distance in the transfer direction. Each second support frame  13  is provided along the vertical direction, and supports both ends of each support frame  11 . 
     In the following description, the direction in which the treatment object M is transferred by the transfer portion  10  is referred to simply as the transfer direction. 
     The mist supply portion  20  is a member for supplying a coolant in mist form into the cooling chamber  120  to cool the treatment object M. The mist supply portion  20  includes: a coolant supply pipe  21 ; and a coolant recovery/supply system  22 . 
     For the coolant of the present embodiment, water, oil, salt or fluorine-based inactive liquid, or the like may be used, for example. 
     A coolant supply pipe  21  is a tubular member extending in the transfer direction. A plurality of (four, in the present embodiment) coolant supply pipes  21  are substantially evenly spaced (spaced at 90° intervals, in the present embodiment) in the circumferential direction of the vacuum container  1  about a transfer route of the treatment object M by the transfer portion  10 . More particularly, the coolant supply pipes  21  are provided at positions spaced at ±45° intervals from the horizontal direction. Each coolant supply pipe  21  is formed over the whole length of the cooling chamber  120  in the transfer direction. 
     Over the whole length in the length direction of each coolant supply pipe  21 , injection portions  23  are provided in a manner spaced from each other by a predetermined distance. The injection portions  23  inject coolant in mist form toward the treatment object M mounted on the transfer portion  10 . 
     The coolant in mist form is influenced by gravity. Therefore, it is preferable that the coolant supply pipes  21  and the injection portions  23  are provided in directions other than the up-down direction, which may produce a difference in supply amount. Furthermore, it is preferable that the coolant supply pipes  21  and the injection portions  23  are provided so that a coolant in mist form is supplied along the horizontal direction. However, if a coolant is supplied along the up-down direction, a different amount of coolant may be supplied in consideration of the influence by gravity. In addition, if not four but three coolant supply pipes  21  are provided, it is preferable that the coolant supply pipes  21  is provided at a zenith position and positions spaced at ±120° intervals from the zenith position in order to decrease the vertical component as much as possible. 
     The coolant recovery/supply system  22  includes: a drain pipe  24  for recovering the coolant supplied into the cooling chamber  120 ; a heat exchanger  25 , connected to the drain pipe  24 , for cooling the recovered drain; ductwork  26  for sending the coolant to the coolant supply pipes  21 ; a pump  27  for sending the coolant cooled in the heat exchanger  25  to the coolant supply pipes  21  via the ductwork  26 ; an inverter  28  for controlling an operation of the pump  27  based on instructions from a control portion  50 , which will be described below; and a liquefier (liquefaction trap)  29  for liquefying the coolant that has been vaporized by receiving heat from the treatment object M. 
     The gas supply portion (adjustment portion)  30  supplies a pressure adjusting gas for adjusting a pressure in the cooling chamber  120  into the cooling chamber  120 . Furthermore, the gas supply portion (adjustment portion)  30  adjust a flow direction of the coolant in mist form in the cooling chamber  120  by use of the pressure adjusting gas. The gas supply portion  30  includes: a gas supply pipe (pipe body)  31 ; and a gas recovery/supply system  32 . 
     For the pressure adjusting gas of the present embodiment, for example an inactive gas such as argon, helium, or nitrogen may be used. 
     A gas supply pipe  31  is a tubular member extending in the transfer direction of the treatment object M. A plurality of (four, in the present embodiment) gas supply pipes  31 A are substantially evenly spaced (spaced at 90° intervals, in the present embodiment) in the circumferential direction of the vacuum container  1  about the transfer route of the treatment object M by the transfer portion  10 . More particularly, the gas supply pipes  31  are provided at three o&#39;clock, six o&#39;clock, nine o&#39;clock, and twelve o&#39;clock (at top, bottom, left, and right positions) of the vacuum container  1  shown in  FIG. 2 . Hereinafter, the gas supply pipes  31  are sometimes referred to, in this order, as a first gas supply pipe  31   a  to a fourth gas supply pipe  31   d . Each gas supply pipe  31  is formed over the whole length of the cooling chamber  120  in the transfer direction. 
     Over the whole length in the length direction of each gas supply pipe  31 , nozzle portions  33  are provide that open toward the treatment object M mounted on the transfer portion  10 . The nozzle portions  33  are spaced from each other by a predetermined distance. 
     The gas recovery/supply system  32  includes: an exhaust pipe  34  for recovering the pressure adjusting gas supplied into the cooling chamber  120 ; ductwork  35  for supplying the pressure adjusting gas to each gas supply pipe  31 ; a fan  36 , connected to the exhaust pipe  34 , for supplying the pressure adjusting gas to each gas supply pipe  31  via the ductwork  35 ; a second inverter  37  for controlling an operation of the fan  36  based on instructions from the control portion  50 , which will be described later; and on-off valves (modification portions, on-off valves)  38  each of which is provided in the vicinity of a connection portion of the ductwork  35  with each gas supply pipe  31 , and opens/closes based on instructions from the control portion  50 . The on-off valves  38  corresponding to the first gas supply pipe  31   a  to the fourth gas supply pipe  31   d  are sometimes referred to, in this order, as a first on-off valve  38   a  to a fourth on-off valve  38   d.    
     In actuality, the fan  36  is made of a bladed wheel and a motor both of which are not illustrated. The second inverter  37  is a member for controlling an operation of the fan  36  by controlling the motor. 
     The temperature measurement portion  40  is a member for measuring a surface temperature of the treatment object M, and consists of: a first temperature sensor  40   a  to a fourth temperature sensor  40   d . The first temperature sensor  40   a  to the fourth temperature sensor  40   d  are provided on surfaces of the treatment object M that respectively faces the first gas supply pipe  31   a  to the fourth gas supply pipe  31   d . The measurement results from the temperature sensors are output to the control portion  50 . 
     For the first temperature sensor  40   a  to the fourth temperature sensor  40   d  of the present embodiment, thermocouples are used. However, a plurality of sites of the treatment object M may be measured by non-contact-type thermometers such as radiation thermometers. 
     The control portion  50  is a member for obtaining measurement results from the temperature measurement portion  40  and also outputting operation instructions to the inverter  28 , the second inverter  37 , and the on-off valves  38 . The control portion  50  outputs operation instructions to the inverter  28  and the second inverter  37  to control the operations of the pump  27  and the fan  36 . Thereby, the supply amounts of the coolant and the pressure adjusting gas are adjusted. Furthermore, the control portion  50  is capable of opening the on-off valves  38  independently at predetermined intervals. 
     Subsequently, a procedure of cooling the heated treatment object M in the cooling chamber  120  in the vacuum heat-treating furnace  100  will be described. 
     Firstly, the treatment object M heated in the heating chamber  110  is transferred into the cooling chamber  120  by the transfer portion  10 . 
     Next, a coolant in mist form is supplied into the cooling chamber  120 . 
     With an instruction from the control portion  50 , the inverter  28  activates the pump  27 . Then, the coolant is supplied to the coolant supply pipes  21  via the ductwork  26 . The coolant supplied to the coolant supply pipes  21  is sprayed in mist form from the injection portions  23  into the cooling chamber  120 . The injection portions  23  inject the coolant in mist form so as to be gradually diffused. Thereby, the coolant in mist form immediately after being sprayed stays around each injection portion  23 , and then gradually falls due to the influence of gravity. Namely, only spraying the coolant from the injection portions  23  may result in the mist density in the cooling chamber  120  is distributed. 
     In the present embodiment, together with the supply of the coolant, the pressure adjusting gas is supplied into the cooling chamber  120 . 
     The second inverter  37  activates the fan  36  by an instruction from the control portion  50 . Thereby, the pressure adjusting gas is supplied to the ductwork  35 . Here, the control portion  50  opens only a specified on-off valve  38 . 
     For example, as shown in  FIG. 2 , the control portion  50  opens only the first on-off valve  38   a  corresponding to the first gas supply pipe  31   a  provided on the right side of the treatment object M. The pressure adjusting gas is supplied to the first gas supply pipe  31   a  through the first on-off valve  38   a , and is then supplied into the cooling chamber  120  via the nozzle portion  33 . Because the nozzle portion  33  opens toward the treatment object M, the pressure adjusting gas is supplied from the nozzle portion  33  of the first gas supply pipe  31   a  toward the treatment object M. Then, the pressure adjusting gas flows from the nozzle portion  33  in the direction toward the treatment object M. 
     The flow direction of the coolant in mist form in the cooling chamber  120  is adjusted to be directed toward the treatment object M (adjustment step) by the flow of the pressure adjusting gas. Because a plurality of nozzle portions  33  are provided in the gas supply pipe  31  in a manner spaced from each other with respect to the transfer direction, the directions of flow of the coolant in mist form are adjusted to be substantially uniform with respect to the transfer direction. As a result, the coolant in mist form flows from the nozzle portions  33  of the first gas supply pipe  31   a  toward the treatment object M. Thus, the coolant in mist form attaches to the right surface of the treatment object M. 
     The coolant evaporates as it attaches to the surface of the heated treatment object M. At the time of this evaporation, the coolant deprives the treatment object M of heat. Therefore, the surface of the treatment object M to which the coolant has attached is cooled (cooling step). The evaporated coolant is liquefied again in the liquefier  29  for reuse. 
     The control portion  50  opens the on-off valve  38  for a predetermined period of time. 
     The predetermined period of time is a span of sufficient time for the pressure adjusting gas supplied into the cooling chamber  120  to form a stable flow, that is, a flow in which the pressure adjusting gas flows in a substantially fixed passage. Therefore, the flows of the pressure adjusting gas and the coolant in mist form become stable. As a result, an amount of coolant sufficient for cooling can be attached to the surface of the treatment object M. 
     Next, after passage of the predetermined period of time, the control portion  50  switches the on-off valves  38  to be opened. 
     For example, the control portion  50  closes the first on-off valve  38   a , and opens the second on-off valve  38   b , instead. With the opening of the second on-off valve  38   b , the pressure adjusting gas is supplied from the nozzle portion  33  of the second gas supply pipe  31   b , and flows from the bottom portion of the vacuum container  1  toward the treatment object M. Accordingly, the flow direction of the coolant in mist form is adjusted so as to be directed from the bottom portion of the vacuum container  1  toward the treatment object M. Thereby, the coolant in mist form attaches to the lower surface of the treatment object M. Therefore, it is possible to cool the lower surface of the treatment object M by opening the second on-off valve  38   b.    
     Subsequently, similarly to the case of opening the second on-off valve  38   b , it is possible to respectively cool the left surface and the upper surface of the treatment object by opening the third on-off valve  38   c  and the fourth on-off valve  38   d.    
     That is, with the opening of only a specified on-off valve  38  by the control portion  50 , a flow of the coolant in mist form is produced in the cooling chamber  120 . Therefore, even if there is a part with low mist density, it is possible to attach an amount of coolant sufficient for cooling to the surfaces of the treatment object M. 
     Furthermore, the control portion  50  finely adjusts the open time of the on-off valve  38 . 
     The temperature measurement portion  40  measures temperatures of the surfaces of the treatment object M, and outputs the measurement results to the control portion  50 . From the measurement results, the control portion  50  checks whether there is temperature distribution of the treatment object M or not. If a specified surface has a higher temperature than the other surfaces, the control portion  50  increases the open time of the on-off valve  38  corresponding to the surface with the higher temperature. 
     For example, if the third temperature sensor  40   c  measures a temperature higher than those by the other sensors, then the left surface of the treatment object M has a temperature higher than those of the other surfaces. Therefore, the control portion  50  increases the open time of the third on-off valve  38   c . As a result, the supply time of the pressure adjusting gas from the nozzle portion  33  of the third gas supply pipe  31   c  is extended, it is possible to cool the left surface of the treatment object M more preferentially than the other surfaces. 
     Accordingly, in the present embodiment, the open time of the on-off valve  38  is finely adjusted based on the temperature distribution in the surfaces of the treatment object M, it is possible to cool the surfaces of the treatment object M more uniformly. 
     Therefore, according to the present embodiment, the following advantageous effects can be obtained. 
     It is possible to attach a sufficient amount of coolant to a surface of the treatment object M with a small amount of attached coolant due to low mist density. Therefore, according to the present embodiment, it is possible to cool the surfaces of the treatment object M substantially uniformly. As a result, it is possible to suppress temperature distribution of the treatment object M when it is cooled. Consequently, it is possible to suppress variation and the like in deformation and hardness, and hence, to avoid the occurrence of poor quality. 
     Second Embodiment 
       FIG. 3  is a front cross-sectional view of a cooling chamber  120  in the present embodiment. 
     In the figure, those components which are the same as the components of the first embodiment shown in  FIG. 1  and  FIG. 2  are denoted by the same reference numerals and description thereof will not be repeated. 
     The cooling chamber  120  of the present embodiment includes a structure in which a plurality of treatment objects M are cooled in a batch. The treatment object M in the present embodiment is formed with a smaller outer shape than the treatment object M in the first embodiment. 
     A tray  14  is mounted on rollers  12  of a transfer portion  10 . In the tray  14 , flow holes for a coolant such as punched holes are formed and arranged in a lattice, and there are provided plate members in a plurality of stages. Treatment objects M are mounted on each stage of the tray  14 . 
     A first temperature sensor  40   a  of a temperature measurement portion  40  is provided on a treatment object M located on the right side in the tray  14 . Similarly, a second temperature sensor  40   b , a third temperature sensor  40   c , and a fourth temperature sensor  40   d  are provided on treatment objects M each located respectively on the lower side, the left side, and the upper side in the tray  14 . Similarly to the first embodiment, non-contact type thermometers such as radiation thermometers may be used instead of the thermocouple-type temperature sensors. 
     A control portion  50  in the present embodiment switches the on-off valves  38  to be opened, before passage of a predetermined period of time, that is, a span of sufficient time for the pressure adjusting gas supplied into the cooling chamber  120  to form a stable flow. Therefore, the flow of the pressure adjusting gas does not become stable but become a turbulent state. Because the pressure adjusting gas is in a turbulent state, the flow of the coolant in mist form supplied into the cooling chamber  120  is also become a turbulent state. 
     In the present embodiment, a plurality of treatment objects M are mounted on the tray  14 . Therefore, it is difficult to attach the coolant in mist form to, for example, the treatment object M mounted in the central portion of the tray  14 . Consequently, by making the flow of the coolant in mist form in the cooling chamber  120  in a turbulent state, an amount of coolant sufficient for cooling can be attached even to treatment objects M to which it is difficult to attach the coolant. 
     Note that on-off valves  38  may be opened simultaneously. In this case, the pressure adjusting gas supplied in different directions from the nozzle portions  33  interfere with one another. Therefore, it is possible to make the flow of the coolant in mist form in the cooling chamber  120  in a turbulent state. 
     Therefore, according to the present embodiment, the following advantageous effects can be obtained. 
     In cooling treatment objects M, an amount of coolant sufficient for cooling can be attached even to treatment objects M to which it is difficult to attach the coolant. Therefore, it is possible to suppress a difference in temperature among multiple treatment objects M when they are cooled. As a result, it is possible to suppress a variance in hardness and the like, and hence, to avoid an occurrence of poor quality. 
     While example embodiments of the invention have been described above with reference to the accompanying drawings, it is obvious that these are not to be considered as limitative of the invention. Shapes, combinations and the like of the constituent members illustrated above are merely examples, and various modifications based on design requirements and the like can be made without departing from the spirit or scope of the invention. 
     For example, in the first embodiment, the on-off valves  38  to be opened are switched after passage of a predetermined period of time. Furthermore, in the second embodiment, the on-off valves  38  to be opened are switched before passage of a predetermined period of time. However, the invention is not limited to these. The first embodiment may use the method of the second embodiment, and vice versa. This is because a more suitable flow state is different according to different surface shapes and the like of the treatment object M. 
     Furthermore, in the above embodiments, the temperature measurement portion  40  is used to measure the temperature of the treatment object M. However, the invention is not limited to this. Instead of using the temperature measurement portion  40 , the on-off valves  38  may be switched at constant intervals measured by the control portion  50  with a timer or the like. 
     Furthermore, in the above embodiments, for a gas for adjusting the flow direction of the coolant in mist form, the pressure adjusting gas for adjusting the pressure in the cooling chamber  120  is used. However, the invention is not limited to this. The cooling gas for cooling the treatment object M may be used. In this case, a heat exchanger for recooling the cooling gas recovered from the cooling chamber  120  may be installed on the exhaust pipe  34 . 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, it is possible to suppress temperature distribution of the treatment object M when it is cooled, to suppress deformation and variation in hardness and the like, and to avoid an occurrence of poor quality. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
         
           
               100 : vacuum heat-treating furnace (heat treatment device) 
               120 : cooling chamber 
               10 : transfer portion 
               20 : mist supply portion 
               30 : gas supply portion (adjustment portion) 
               31 : gas supply pipe (pipe body) 
               33 : nozzle portion 
               38 : on-off valve (modification portion, on-off valve) 
               40 : temperature measurement portion 
               50 : control portion (control portion, second control portion) 
             M: treatment object