Abstract:
A coupling device which contributes to a further reduction in the space required to transport a die etc., in which first and second joints are simplified in structure and downsized, and that is advantageous when multiple sets of such first and second joints are installed. The coupling device comprises a female joint and a male joint. The female joint is fitted on a mold and comprises a first valve casing, a first valve body, and a first open/close valve having a first valve seat and a first valve portion. The male joint is fitted on a clamping plate of an injection molding machine and comprises a second valve casing, a second valve body, and a second open/close valve having a second valve seat and a second valve portion. The coupling device further comprises a valve body drive unit. When, in a condition where the front ends of the first and second valve casings and are in contact with each other, the valve body drive unit drives and advances, in the male joint, only the second valve body relative to the second valve casing, the first and second valve bodies and are driven to the valve opening side.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a coupling device comprising a female joint and a male joint capable of connecting/disconnecting the first and second fluid passages in first and second members. 
     The prior art put into practical use a coupling device comprising a first joint fitted on a first member such as a mold and work palette and a second joint fitted on a second member such as a mold fixture of a molding machine and a base member of a machining tool, when coupling/decoupling the first and second members in a predetermined positional relationship, for connecting/disconnecting the first and second fluid passages via the first and second joints in order to supply a fluid (cooling water, pressurized fluid, and so on) from one of the first and second fluid passages in the first and second members to the other while the first and second members are coupled (for example see the Patent Document 1). 
     The first and second joints consist of male and female joints, respectively, each having an open/close valve. The open/close valves of the male and female joints are closed while the male and female joints are separated. On the other hand, when the male and female joints are connected, the leading end portion of the male joint is inserted in the female joint and the leading end portion of the female joint is inserted in the leading end portion of the male joint so as to open the open/close valves of the male and female joints, whereby the first and second fluid passages are connected. In such a coupling device, the male and female joints generally protrude outward from the first and second members. 
     In the coupling device of the Patent Document 1, the male joint is fitted on a work pallet downward and the female joint is fitted on a base member of a machining tool upward. The male joint has a casing member fixed to the work pallet, a valve casing fitted in the casing member and protruding downward from the casing member, and a shaft-like valve body fitted in the valve casing movably in the advancing/retreating direction. The open/close valve is constituted by a valve seat and a valve portion provided at the lower ends of the valve casing and valve body. 
     A hydraulic cylinder for driving the female joint upward is provided to the base member of the machining tool. The female joint has a main body case fitted in the cylinder barrel of the hydraulic cylinder movably in the advancing/retreating direction and protruding upward from the cylinder barrel, a cylindrical member mounted in the main body case movably in the advancing/retreating direction, and a shaft-like valve body provided inside the cylindrical member and fixed to the body casing at the lower end. The open/close valve is constituted by a valve seat and a valve portion provided at the upper ends of the cylindrical member and valve body. 
     For connecting the separated male and female joints, the female joint is driven upward by the hydraulic cylinder while the male and female joints face each other one above the other. Here, first, the main body case, cylindrical member, and valve body of the female joint are moved upward together. The cylindrical member stops moving upward when its upper end abuts on the lower end of the valve casing of the male joint. Then, the main body case and valve body move upward together. Then, the valve body of the female joint is inserted in the valve casing of the male joint so that the valve body of the male joint is moved upward. The valve casing of the male joint is inserted in the main body case of the female joint so that the cylindrical member is moved downward in relation to the body casing and valve body in the female joint, whereby the open/close valves of the female and male joints are opened.
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2000-346266.   

     SUMMARY OF THE INVENTION 
     For example, in order to attach/detach a mold to the mold fixture of a horizontal injection molding machine, the mold is moved in parallel to the fixing surface of the mold fixture. In doing so, there is a demand that the space between the mold and mold fixture is minimized to save the conveyance space. However, when a conventional clamping member is used to fix a mold to the fixing surface of the mold fixture, the clamping member attached to the fixing surface becomes an obstacle. Then, a possible solution is to also attach/detach the clamping member when a mold is attached/detached to/from the mold fixture. In this way, the workload of attaching/detaching a mold to/from the mold fixture is increased. 
     Then, multiple magnets are installed in the mold fixture and the mold fixture is alternatively switched between the active state in which a magnetic adsorption force is generated and the inactive state in which a magnetic adsorption force is not generated. In this way, the mold can be fixed to the fixing surface of the mold fixture without using a conventional clamping member, whereby the above problem with conventional clamping members can be eliminated. However, as in the case of using a conventional clamping member, when a male joint and a female joint are fitted on the mold and mold fixture to constitute a coupling device and the male and female joints protrude outward from the first and second members as in the Patent Document 1, the space between the mold and mold fixture should be increased for the protrusion while the mold is conveyed to attach/detach it to/from the mold fixture. It is difficult to fulfill the demand of saving the conveyance space. 
     In the prior art coupling device, as in the Patent Document 1, when the female joint has a hydraulic cylinder driving the entire female joint including the main body case, cylindrical member with a valve seat, and valve body with a valve portion as the valve body drive means for driving the valve bodies of the male and female joints to the opening positions in order to connect the male and female joints, the hydraulic cylinder must have a cylinder barrel housing the entire female joint and, therefore, is increased in size. For this reason, the female joint structure including the female joint and hydraulic cylinder is increased in size. The space for fitting such a female joint structure may not be reserved on an existing mold, work pallet, mold fixture of a molding machine, base member of a machining tool, etc. 
     For operating the coupling device, the male joint should protrude from the first member but the female joint does not necessarily protrude from the second member while the male and female joints are not connected. However, because the female joint structure is increased in size as suggested with regard to the above problem, the female joint may have to protrude from the second member and, therefore, it is difficult to achieve any improvement in saving the conveyance space. In addition, the female joint has a complex structure because of the main body case and accompanying members besides the cylindrical member having a valve seat and the valve body having a valve portion, which contributes to the female joint structure being increased in size. 
     Furthermore, for example, there is a demand for installation of multiple sets of male and female joints on the mold and the mold fixture of an injection molding machine in order to provide multiple lines of coolant passages in the mold. In such a case, each one of the multiple female joints needs a hydraulic cylinder and each female joint structure is increased in size; the entire coupling device is significantly increased in size. Therefore, the multiple sets of male and female joints may not be provided in a proper arrangement. Furthermore, the total weight of multiple female joint structures and members for fitting them is increased and the workload of moving them is increased. 
     The object of the present invention is to provide a coupling device in which the space for conveying a mold is further saved, the first and second joints are simplified in structure and downsized, and multiple sets of first and second joints are advantageously provided. 
     The coupling device comprises a female joint having a first open/close valve and a male joint having a second open/close valve for connecting/disconnecting the first and second fluid passages in first and second members, wherein the female joint comprises a first valve casing fitted in a first fitting hole formed in the first member and having a first valve seat in a leading end portion, a first valve body fitted in the first valve casing movably in an advancing/retreating direction and having in a leading end portion a first valve portion abutting on the first valve seat from an inside, and a first biasing means for biasing the first valve body toward a closing position; the male joint comprises a second valve casing fitted in a second fitting hole formed in the second member and having a second valve seat in a leading end portion, a second valve body fitted in the second valve casing movably in an advancing/retreating direction and having in a leading end portion a second valve portion abutting on the second valve seat from an outside, and a second biasing means for biasing the second valve body toward a closing position; a surface of the first member and a leading end face of the first valve casing of the female joint are substantially flush with each other and a surface of the second member and a leading end face of the second valve casing of the male joint are substantially flush with each other; and a valve body drive means for driving the first and second valve bodies to opening positions while leading ends of the first and second valve casings abut on each other is provided. 
     Furthermore, one of the first and second members consists of a mold or a joint fitting member (a first joint fitting member) fixed to the mold in the invention. In the invention, the other of the first and second members consists of a clamping plate for fixing the mold in a molding machine, the clamping plate having multiple magnets installed for generating a magnetic adsorption force and being alternatively switched between an active state in which the magnetic adsorption force is generated and an inactive state in which the magnetic adsorption force is not generated. In the invention according to some embodiments, the other of the first and second members consists of a second joint fitting member fixed to a clamping plate. In the invention according to some embodiments the other of the first and second members consists of a platen for fixing the mold in a molding machine, the platen having multiple magnets installed for generating a magnetic adsorption force and being alternatively switched between an active state in which the magnetic adsorption force is generated and an inactive state in which the magnetic adsorption force is not generated. In the invention according to claim  4 , some embodiments the other of the first and second members consists of a second joint fitting member fixed to a platen. 
     In the coupling device  4 , when the female and male joints are separated, the first valve portion of the first valve body biased by the first biasing means toward the closing position abuts on and is pushed to the first valve seat of the first valve casing from the inside so that the first open/close valve is closed in the female joint and the second valve portion of the second valve body biased by the second biasing means toward the closing position abuts on and is pushed to the second valve seat of the second valve casing from the outside so that the second open/close valve is closed in the male joint. For connecting the separated female and male joints, first, the leading ends of the first and second valve casings are brought to abut on each other. Here, the leading ends of the first and second valve casings can abut on each other when the first and second members are coupled in a predetermined positional relationship. Alternatively, the leading ends of the first and second valve casings can abut on each other when the second valve casing and second valve body of the male joint or the first valve casing and first valve body of the female joint are advanced together after the first and second valve casings closely face each other. Then, while the leading ends of the first and second valve casings abut on each other, the valve body drive means drives the first and second valve bodies to the opening positions against the biasing forces of the first and second biasing means, whereby the first and second open/close valves are opened to connect the female and male joints and connect the first and second fluid passages in the first and second members. 
     The clamping plate or platen of a molding machine has multiple magnets installed for generating a magnetic adsorption force and is alternatively switched between the active state in which the magnetic adsorption force is generated and the inactive state in which the magnetic adsorption force is not generated, whereby the mold can be fixed to the clamping plate or platen without using a conventional clamping member. Furthermore, the surface of the first member and the leading end face of the first valve casing of the female joint are substantially flush with each other and the surface of the second member and the leading end face of the second valve casing of the male joint are substantially flush with each other, whereby the mold can be moved in parallel to the fixing surface of the clamping plate or platen in conveying the mold for attaching/detaching it to/from the clamping plate or platen with the minimized space between the mold and clamping plate or between the mold and platen, saving the conveyance space. 
     The following structures are included in various embodiments. 
     (1) The valve body drive means advances only the second valve body in relation to the second valve casing in the male joint so as to drive the first and second valve bodies to the opening positions while the leading ends of the first and second valve casings abut on each other. 
     (2) The valve body drive means has a piston part provided integrally with the second valve body of the male joint, a fluid pressure operation chamber applying a fluid pressure to the piston part, and a fluid pressure supply means for supplying the fluid pressure to the fluid pressure operation chamber. 
     (3) Multiple sets of the female and male joints are provided and the fluid pressure supply means is shared by the multiple sets of female and male joints. 
     (4) The first valve casing of the female joint is fitted in the first fitting hole movably in the retreating direction and a first valve casing biasing means for biasing the first valve casing outward is provided. 
     (5) The second valve casing of the male joint is fitted in the second fitting hole movably in the advancing direction, a second valve casing biasing means for biasing the second valve casing in the retreating directions is provided, and when a fluid pressure is supplied to the fluid pressure operation chamber while the first and second valve casings closely face each other, the second valve casing and second valve body are advanced together so that the leading ends of the first and second valve casings abut on each other and, then, the second valve body is advanced in relation to the second valve casing. 
     (6) The second valve seat of the male joint consists of an annular sealing member fitted on the leading end of the second valve casing and the annular sealing member is capable of abutting on the leading end of the first valve casing of the female joint. 
     (7) The valve body drive means is capable of advancing the second valve body so as to drive the first and second valve bodies to the opening positions and connect the female and male joints while the leading ends of the first and second valve casings abut on each other with the axes of the female and male joints being shifted within a predetermined range. 
     (8) The molding machine is a horizontal injection molding machine. 
     The coupling device, particularly, one of the first and second members consists of a mold or a first joint fitting member fixed to the mold and the other consists of a clamping plate for locking the mold in a molding machine, the clamping plate having multiple magnets installed for generating a magnetic adsorption force and being alternatively switched between the active state in which the magnetic adsorption force is generated and the inactive state in which the magnetic adsorption force is not generated, whereby the mold can be fixed to the clamping plate without using a conventional clamping member. Furthermore, the surface of the first member and the leading end face of the first valve casing of the female joint are substantially flush with each other and the surface of the second member and the leading end face of the second valve casing of the male joint are substantially flush with each other, whereby the mold can be moved in parallel to the fixing surface of the clamping plate in conveying the mold for attaching/detaching it to/from the clamping plate with the minimized space between the mold and clamping plate, achieving improvement in saving the conveyance space. Additionally, the female and male joints can simply and securely be connected/disconnected and the workload of attaching/detaching the mold to/from the clamping plate can significantly be reduced. 
     In the coupling device one of the first and second members consists of a mold or a first joint fitting member fixed to the mold and the other consists of a second joint fitting member fixed to a clamping plate for fixing the mold in a molding machine, the second joint fitting member being fixed to the clamping plate having multiple magnets installed for generating a magnetic adsorption force and alternatively switched between the active state in which the magnetic adsorption force is generated and the inactive state in which the magnetic adsorption force is not generated. Additionally, the male or female joint can easily be provided by fixing the second joint fitting member to an existing clamping plate, thereby improving versatility. 
     The coupling device, particularly, one of the first and second members consists of a mold or a joint fitting member fixed to the mold and the other consists of a platen for fixing the mold in a molding machine, the platen having multiple magnets installed for generating a magnetic adsorption force and being alternatively switched between the active state in which the magnetic adsorption force is generated and the inactive state in which the magnetic adsorption force is not generated, whereby the mold can be fixed to the platen without using a conventional clamping member. Furthermore, the surface of the first member and the leading end face of the first valve casing of the female joint are substantially flush with each other and the surface of the second member and the leading end face of the second valve casing of the male joint are substantially flush with each other, whereby the mold can be moved in parallel to the fixing surface of the platen in conveying the mold for attaching/detaching it to/from the platen with the minimized space between the mold and platen, achieving improvement in saving the conveyance space. Additionally, the female and male joints can simply and securely be connected/disconnected and the workload of attaching/detaching the mold to/from the platen can significantly be reduced. In addition, the clamping plate can be eliminated; therefore, the molding machine can be simplified in structure and the molten resin injection path for injecting molten resin into the cavities of the molds from the back of the platen can be shortened as the clamping plate is eliminated, whereby the molten resin in a proper molten state can be injected into the cavities of the molds, increasing the accuracy of injection molding. 
     In the coupling device one of the first and second members consists of a mold or a first joint fitting member fixed to the mold and the other consists of a second joint fitting member fixed to a platen for fixing the mold in a molding machine, the second joint fitting member being fixed to the platen having multiple magnets installed for generating a magnetic adsorption force and alternatively switched between the active state in which the magnetic adsorption force is generated and the inactive state in which the magnetic adsorption force is not generated. Additionally, the male or female joint can easily be provided by fixing the second joint fitting member to the platen, thereby improving versatility. 
     In the coupling device the valve body drive means advances only the second valve body in relation to the second valve casing in the male joint so as to drive the first and second valve bodies to the opening positions while the leading ends of the first and second valve casings abut on each other, whereby the female and male joints can be simplified in structure and downsized. In addition, as for the male joint, a simple and small fluid pressure cylinder can be used for advancing the second valve body in relation to the second valve casing by means of the valve body drive unit, whereby the male joint structure including the male joint and fluid pressure cylinder can be simplified and downsized. 
     Hence, the space for fitting the female joint or male joint (male joint structure) can be assured on an existing mold or a joint fitting member (first joint fitting member) fixed to a mold, a clamping plate or platen of a molding machine, or a second joint fitting member fixed to the clamping plate or platen. Furthermore, the valve body drive means drives only the first and second valve bodies to open the first and second open/close valves while the leading ends of the first and second valve casings abut on each other. Therefore, the intended behavior of the coupling device is assured in the configuration in which the surface of the first member and the leading end face of the first valve casing of the female joint are substantially flush with each other and the surface of the second member and the leading end face of the second valve casing of the male joint are substantially flush with each other. 
     The female joint and male joint (male joint structure) can be downsized and multiple sets of female and male joints are properly arranged in the case of providing multiple sets of male and female joints on the first and second members. Furthermore, the total weight of the first member and multiple female joints will not excessively be increased; therefore, increase in the workload of moving them can be suppressed. The total weight of the second member and multiple male joints (mal joint structure) will not excessively be increased; therefore, increase in the workload of moving them can be suppressed. 
     In the coupling device the valve body drive means has a piston part provided integrally with the second valve body of the male joint, a fluid pressure operation chamber applying a fluid pressure to the piston part, and a fluid pressure supply means for supplying the fluid pressure to the fluid pressure operation chamber, whereby the valve body drive means securely advances the second valve body in relation to the second valve casing. Furthermore, the piston part is provided integrally with the second valve body and the fluid pressure operation chamber can have a simplified structure and easily be provided, whereby the male joint structure can certainly be simplified and downsized. 
     In the coupling device multiple sets of the female and male joints are provided and the fluid pressure supply means is shared by the multiple sets of female and male joints, whereby it is unnecessary to provide as many fluid pressure supply devices as the number of female joints and, therefore, the coupling device can be simplified in structure. 
     In the coupling device the first valve casing of the female joint is fitted in the first fitting hole movably in the retreating direction and a first valve casing biasing means for biasing the first valve casing outward is provided, whereby errors in manufacturing the female and male joints and errors in assembling them to the first and second members are absorbed when the mold is fixed to the clamping plate or platen, ensuring that the leading ends of the first and second valve casings abut on each other. 
     In the coupling device the second valve casing of the male joint is fitted in the second fitting hole movably in the advancing direction, a second valve casing biasing means for biasing the second valve casing in the retreating direction is provided, and, when a fluid pressure is applied to the fluid pressure operation chamber while the first and second valve casings closely face each other, the second valve casing and second valve body are advanced together so that the leading ends of the first and second valve casings abut on each other and, then, the second valve body is advanced in relation to the second valve casing, whereby prior to connecting the female and male joints, the mold is fixed to the clamping plate or platen so that the first and second valve casings closely face each other and, then, the leading ends of the first and second valve casings are brought to securely abut on each other and the female and male joints are securely connected. 
     In the coupling device the second valve seat of the male joint consists of an annular sealing member fitted on the leading end of the second valve casing and the annular sealing member is capable of abutting on the leading end of the first valve casing of the female joint, whereby this single annular sealing member constitutes the second valve seat of the male joint and ensures that the leading ends of the first and second valve casing abut on each other in a sealed manner. Hence, the male joint can be simplified in structure (reduced in the number of parts) while these two functions are ensured. 
     In the coupling device the valve body drive means is capable of advancing the second valve body so as to drive the first and second valve bodies to the opening positions and connect the female and male joints while the leading ends of the first and second valve casings abut on each other with the axes of the female and male joints being shifted within a predetermined range, whereby the valve body drive means can securely drive the first and second valve bodies to the opening positions to connect the female and male joints while errors in positioning the mold on the clamping plate or platen and errors in assembling the female and male joints are tolerated. 
     In the coupling device the molding machine is a horizontal injection molding machine, whereby the demand for moving a mold in parallel to the fixing surface of a clamping plate or platen in conveying the mold for fixing it to the clamping plate or platen in a horizontal injection machine can be fulfilled with improvement in saving the conveyance space since the space between the mold and clamping plate or between the mold and platen can be minimized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a horizontal injection molding machine of embodiment 1; 
         FIG. 2  is an illustration of the surface of the core part including the female joint of the coupling device of embodiment 1; 
         FIG. 3  is an illustration of the surface of the core part including the male joint of the coupling device of embodiment 1; 
         FIG. 4  is an illustration of the surface of the core part of the clamping device of embodiment 1; 
         FIG. 5  is an exploded perspective view of the core part of the clamping device of embodiment 1; 
         FIG. 6  is a cross-sectional view of the core part of the clamping device of embodiment 1 in the active state; 
         FIG. 7  is a cross-sectional view of the core part of the clamping device of embodiment 1 in the inactive state; 
         FIG. 8  is a cross-sectional view of the male and female joints of embodiment 1 in the separated state; 
         FIG. 9  is a cross-sectional view of the male and female joints of embodiment 1 in the abutting state; 
         FIG. 10  is a cross-sectional view of the male and female joints of embodiment 1 in the connected state; 
         FIG. 11  is a perspective view of the core part including the clamping plate and male joint of embodiment 2; 
         FIG. 12  is a cross-sectional view of the male and female joints of embodiment 2 in the separated state; 
         FIG. 13  is a cross-sectional view of the male and female joints of embodiment 2 in the closely facing state; 
         FIG. 14  is a cross-sectional view of the male and female joints of embodiment 2 in the abutting state; 
         FIG. 15  is a cross-sectional view of the male and female joints of embodiment 2 in the connected state; 
         FIG. 16  is a perspective view of the core part including the clamping plate and male joint of a modification of embodiment 2; 
         FIG. 17  is a side view of a horizontal injection molding machine of embodiment 3; 
         FIG. 18  is an illustration of the surface of the core part including the female joint of the coupling device of embodiment 3; 
         FIG. 19  is a perspective view of the core part including the platen and male joint of embodiment 4; and 
         FIG. 20  is a perspective view of the core part including the platen and male joint of a modification of embodiment 4. 
     
    
    
     DESCRIPTION OF NUMERALS 
     
         
         
           
             M 2  mold 
               1 ,  1 A horizontal injection molding machine 
               2 ,  2 A fixed platen 
               3 ,  3 A movable platen 
               11  clamping plate 
               15 ,  100 ,  180 ,  190  coupling device 
               20 ,  110  female joint 
               21 ,  111  first fluid passage 
               22 ,  112  first fitting hole 
               25 ,  115  male joint 
               26 ,  116  second fluid passage 
               27 ,  117  second fitting hole 
               30 ,  120  first valve casing 
               31 ,  121  first valve seat 
               34  compression coil spring 
               35 ,  125  first valve body 
               36 ,  126  first valve portion 
               40 ,  130  compression coil spring 
               45 ,  135  first open/close valve 
               50 ,  145  second valve casing 
               51 ,  146  second valve seat 
               55 ,  150  second valve body 
               55   a ,  150   a  piston part 
               56 ,  151  second valve portion 
               60 ,  155  compression coil spring 
               61 ,  166  annular sealing member 
               65 ,  160  second open/close valve 
               70 ,  170  valve body drive unit 
               71 ,  171  fluid pressure operation chamber 
               72 ,  172  fluid pressure supply unit 
               101  joint fitting member 
               165  compression coil spring 
           
         
       
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The coupling device of the present invention comprises a female joint and a male joint, each comprising a valve casing, a valve body, and an open/close valve, and a valve body drive means for driving the valve bodies of the female and male joints to the opening positions while the leading ends of the valve casings of the female and male joints abut on each other. 
     Embodiment 1 
     In the coupling device of embodiment 1, the female joint is fitted on a mold as the first member and the male joint is fitted on a clamping plate as the second member that is a platen auxiliary for fixing the mold in a horizontal injection molding machine, whereby the first fluid passage in the mold and the second fluid passage in the clamping plate are connected/disconnected when the mold is fixed/unfixed to/from the clamping plate. 
     First, a horizontal injection molding machine  1  will be explained. 
     As shown in  FIGS. 1 and 2 , the horizontal injection molding machine  1  comprises a fixed platen  2  and a movable platen  3  for fixing a mold M (a fixed mold M 1  and a movable mold M 2 ), four guide rods  4  for guiding and supporting the movable platen  3  movably toward/away from the fixed platen  2 , a movable platen drive mechanism  5  for driving the movable platen  3  toward/away from the platen  2  for closing/opening the mold M, an injection mechanism  6  for supplying molten synthetic resin in the cavity of the mold M in the closed state, and an eject mechanism  7  for ejecting the molded article from the movable mold M 2 . 
     The fixed platen  2  and movable platen  3  are each a square platen. The four guide rods  4  are inserted and fixed in the four corners of the fixed platen  2 . They are slidably inserted in the four corners of the movable platen  3 . The injection mechanism  6  has an injection cylinder  6   a  connected to the fixed platen  2 . The eject mechanism  7  has one or multiple ejector pins  7   a , an ejector plate  7   b  to which the ejector pins  7   a  are coupled at the base end, and a fluid pressure cylinder  7   c  for driving the ejector plate  7   b.    
     The horizontal injection molding machine  1  comprises a clamping device  8 A fixing/unfixing the fixed mold M 1  and a clamping device  8 B fixing/unfixing the movable mold M 2 . The clamping devices  8 A and  8 B each comprise a magnetic clamping device provided with a clamping plate  10  or  11  having multiple magnets installed for generating a magnetic adsorption force and alternatively switched between the active state in which the magnetic adsorption force is generated and the inactive state in which the magnetic adsorption force is not generated. The clamping plates  10  and  11  are fixed to the fixed platen  2  and movable platen  3  and have fixing surfaces  10   a  and  11   a , respectively. 
     As shown in  FIGS. 4 to 7 , the clamping plate  11  of the clamping device  8 B consists of a steel plate made of magnetic material nearly equal to the movable platen  3  in size, from which nearly square portions corresponding to the four corners of the movable platen  3  are removed. The clamping plate  11  is fixed to the surface of the movable platen  3  and has ejector pin holes  11   b  formed in the center part. A predetermined number of magnet units  80  are provided on the clamping plate  11  in a predetermined manner. For example, four sets of magnet unit groups (i.e. total of 16 magnet units  80 ), each group comprising four magnet units  80 , arranged next to each other on the top and bottom and right and left and are placed on the clamping plate  11  at positions symmetrical about the center of the clamping plate  11 . 
     The multiple magnetic units  80  are housed in a recess  11   c  formed in the clamping plate  11  from the fixing surface  11   a  side. Each magnetic unit  80  has a magnetic steel block  81  facing the fixing surface  11   a , an Alnico magnet  82  placed on the back of the steel block  81 , a coil  83  wound around the Alnico magnet  82  for switching the polarity of the Alnico magnet  82 , and multiple (for example eight) neodymium permanent magnets  84  arranged around the outer periphery of the steel block  81 . The permanent magnets  84  between the steel blocks  81  of adjacent magnet units  80  are shared by these magnet units  80 . 
     The steel block  81  and Alnico magnet  82  have a square form. The steel block  81  has a bolt hole  81   a  and the Alnico magnet has a hole  82   a . Interposed between the steel block  81  and the bottom wall  11   d  of the recess  11   c , the Alnico magnet  82  and coil  83  are fastened to the bottom wall  11   d  of the recess  11   c  by a hexagon socket head bolt  85  consisting of a nonmagnetic material (for example SUS304) inserted in the bolt hole  81   a  and hole  82   a . The multiple permanent magnets  84  are fixed to the clamping plate  11  or steel block  81  by some fixing means. 
     The polarities of the permanent magnets  84  around the steel block  81  of one of two adjacent magnet units  80  and the polarities of the permanent magnets  84  around the steel block  81  of the other magnet unit  80  are reversed to each other. The polarity of the Alnico magnet  82  can be reversed by magnetic induction of a magnetic field generated by the coil  83 . The polarity of the Alnico magnet  82  corresponding to the steel block  81  of one of two adjacent magnet units  80  and the polarity of the Alnico magnet  82  corresponding to the steel block  81  of the other magnet unit  180  are reversed to each other. 
     For fixing the mold M 2  to the clamping plate  11 , first, as shown in  FIG. 7 , the mold M 2  is positioned and placed in contact with the fixing surfaces  11   a  of the clamping plate  11  in the inactive state in which the magnetic adsorption force is not generated. The coil  83  is energized in a predetermined direction for several seconds so that, as shown in  FIG. 6 , the polarity of the Alnico magnet  82  is switched and the magnetic flux caused by the Alnico magnet  82  has the same direction as the magnetic flux caused by the permanent magnets  84 , whereby a magnetic circuit having a magnetic path partly formed by the mold M 2  is established. Then, the active state in which a potent magnetic adsorption force is generated is created and the magnetic adsorption force serves to fix the mold M 2  to the clamping plate  11 . 
     For unfixing the mold M 2  from the clamping plate  11 , the coil  83  is energized in the direction opposite to that for fixing the mold M 2  for several seconds so that, as shown in  FIG. 7 , the polarity of the Alnico magnet  82  is reversed and the magnetic flux caused by the Alnico magnet  82  does not go beyond the fixing surface  11   a  of the clamping plate  11 , whereby the magnetic force does not work on the mold M 2 , creating the inactive state in which the magnetic adsorption force is not generated. Here, the clamping device  8 A has basically the same structure as the clamping device  8 B and will not be described in detail. The clamping plate  10  of the clamping device  8 A has a locating ring in the center part. 
     The coupling device  15  will be described hereafter. 
     As shown in  FIGS. 1 to 3 , the coupling device  15  comprises multiple (for example five) female joints  20  fitted on the mold M 2 , and multiple (for example five) male joints  25  fitted on the clamping plate  11  and paired with the female joints  20 . Upon fixing/unfixing the mold M 2  to/from the clamping plate  11  in a predetermined positional relationship, multiple (for example five) first fluid passages  21  in the mold M 2  and multiple (for example five) second fluid passages  26  in the clamping plate  11  can be connected/disconnected through multiple sets of female and male joints  20  and  25 . 
     Here, the clamping plate  11  has multiple fluid ports  26   a  for the multiple second fluid passages  26 . The multiple fluid ports  26   a  are connected to a fluid supply/discharge unit  31  via multiple fluid hoses  32 . A control device  33  controls the fluid supply/discharge unit  31 . With the multiple first and second fluid passages  21  and  26  being connected, the fluid supply/discharge unit  31  is driven to supply/discharge a fluid to/from the multiple first fluid passages  21  in the mold M 2 . For example, the fluid supply/discharge unit  31  comprises a coolant supply/discharge unit and, in such a case, circulates a coolant through the mold M 2 . 
     Here, the coupling device  15  can connect/disconnect the multiple first fluid passages  21  in the movable mold M 2  and the multiple second fluid passages  26  in the clamping plate  11  as described above. A coupling device capable of connecting/disconnecting the multiple fluid passages in the fixed mold M 1  and the multiple fluid passages in the clamping plate  10  can be provided in a similar manner to the coupling device  15 . 
     The female joint  20  and male joint  25  will be described in detail hereafter. The female joint  20  will be described on the premise that the arrow a points to the leading end in  FIG. 8  and the male joint  25  will be described on the premise that the arrow b points to the leading end in  FIG. 8 . 
     As shown in  FIGS. 3 and 8  to  10 , the female joint  20  comprises a first valve casing  30  fitted in a first fitting hole  22  formed in the mold M 2  and having a first valve seat  31  in the leading end portion, a first valve body  35  fitted in the first valve casing  30  movably in the advancing/retreating direction and having in the leading end portion a first valve portion  36  abutting on the first valve seat  31  from the inside (base end side), and a compression coil spring  40  as the first biasing means for biasing the first valve body  35  toward the closing position (toward the leading end) in relation to the first valve casing  30 . 
     The first fitting hole  22  is circular in cross-section and open on the surface of the mold M 2  (the surface facing the fixing surface  11   a  when the mold M 2  is fixed to the clamping plate  11 ). A fluid passageway  21   a  of the first fluid passage  21  is connected to the peripheral surface of the first fitting hole  22  and a fluid passageway  21   b  of the first fluid passage  21  is connected to the base end face of the first fitting hole  22 . It is possible to use at least one of the fluid passageways  21   a  and  21   b  and omit the fluid passageway  21   a  or  21   b . The aforementioned surface of the mold M 2  and the leading end face of the first valve casing  30  are substantially flush with each other and the first valve seat  31  and first valve portion  36  constitute a first open/close valve  45 . 
     The first valve casing  30  has a barrel  30   a  and a leading protrusion  30   b . The leading end portion of the barrel  30   a  is slidably fitted in the first fitting hole  22  and an annular seal  32  is fitted around the outer periphery of the leading end portion of the barrel  30   a . A stop ring  33  is placed on the peripheral surface of the leading end portion of the first fitting hole  22 . Engaging with the stop ring  33 , the first valve casing  30  does not move toward the leading end. In this state, the leading protrusion  30   b  slightly protrudes to the leading end from the first fitting hole  22  (for example by 0.3 mm). In this state, the leading end of the leading protrusion  30   b  can be retreated in the first fitting hole  22  so that the first valve casing  30  is moved in the first fitting hole  22  in the retreating direction. 
     A passageway  23   a  is formed in the first valve body  35  and a passage entrance  23   b  connecting the passageway  23   a  and the outside is formed in the leading protrusion  30   b . The leading protrusion  30   b  has a tapered inner periphery at the base end of the passage entrance  23   b , the diameter of which decreasing toward the leading end. The first valve seat  31  is formed on this tapered inner periphery. An annular groove  30   c  is formed on the outer periphery of the barrel  30   a  in the longitudinally middle portion. An annular passageway  23   c  communicating with the fluid passageway  21   a  is formed between the annular groove  30   c  and the peripheral surface of the first fitting hole  22 , whereby multiple passageways  23   d  connecting the passageways  23   a  and  23   c  are formed in the barrel  30   a . A compression coil spring  34  as the first valve casing biasing means for biasing the first valve casing  30  outward (toward the leading end) is fitted on the barrel  30   a  between a flange  30   d  near the base end of the annular groove  30   c  of the barrel  30   a  and the base end face of the first fitting hole  22 . 
     The first valve body  35  has, from the base end to the leading end, a shaft part  35   a , a large-diameter head part  35   b , a middle head part  35   c , and a leading head part  35   d . An annular member  37  is provided in the first valve casing  30  at the base end portion. A stop ring  38  is provided on the inner surface of the first valve casing  30  at the base end. Engaging with the stop ring  38 , the annular member  37  does not move to the base end. A barrel  37   a  extending toward the leading end is formed in the center part of the annular member  37 . The shaft part  35   a  of the first valve body  35  is slidably fitted and guided in the barrel  37   a . Multiple passageways  23   e  connecting the passageway  23   a  and fluid passageway  21   b  are formed in the annular member  37 . 
     A compression coil spring  40  is fitted on the shaft part  35   a  of the first valve body  35  between the large-diameter head part  35   b  and annular member  37 . An annular seal  39  is fitted on the outer periphery of the base end portion of the leading head part  35   a  of the first valve body  35 , constituting a first valve portion  36 . When the first open/close valve  45  is closed, the leading end portion of the leading head part  35   d  of the first valve body  35  is fitted in the passage entrance  23   b  of the first valve casing  30  and the leading end faces of the first valve body  35  and first valve casing  30  are nearly continuous and flush with each other. 
     As shown in  FIGS. 2 and 8  to  10 , the male joint  25  comprises a second valve casing  50  fitted in a second fitting hole  27  formed in the clamping plate  11  and having a second valve seat  51  in the leading end portion, a second valve body  55  fitted in the second valve casing  50  movably in the advancing/retreating direction and having in the leading end portion a second valve portion  56  abutting on the second valve seat  51  from the outside (the leading end side), and a compression coil spring  60  as the second biasing means for biasing the second valve body  55  toward the closing position (toward the base end) in relation to the second valve casing  50  somewhere on the clamping plate  11  other than the area where multiple magnet units  80  are installed (for example along a side of the clamping plate  11 ). 
     The second fitting hole  27  is circular in cross-section and open on the surface (the fixing surface  11   a ) of the clamping plate  11 . A second fluid passage  26  is connected to the peripheral surface of the second fitting hole  27 . The aforementioned surface  11   a  of the clamping plate  11  and the leading end face of the second valve casing  50  are substantially flush with each other and the second valve seat  51  and second valve portion  56  constitute a second open/close valve  65 . 
     The second valve casing  50  has a barrel  50   a  and a leading wall  50   b . A leading protrusion  50   c  is formed on the leading wall  50   b . The barrel  50   a  is fitted in the second fitting hole  27 . The base end portion of the barrel  50   a  is screwed on and fixed to the peripheral surface of the second fitting hole  27 . The leading end face of the leading protrusion  50   c  and the surface  11   a  of the clamping plate  11  are substantially flush with each other. Annular seals  52  and  53  are fitted on the outer periphery of the barrel  50   a  in the leading end portion and in the longitudinally middle portion. 
     A passageway  54   a  is formed in the second valve casing  50  and a passage entrance  54   b  connecting the passageway  54   a  to the outside is formed in the leading wall  50   b . Formed in the leading wall  50   b  at the leading end of the passage entrance  54   b , an annular recess  50   d  having a diameter larger than the passage entrance  54   b  opens at the leading end. An annular sealing member  61  is fitted in the annular recess  50   d . The annular sealing member  61  constitutes a second valve seat  51  and abuts on the leading end of the first valve casing  30  of the female joint  20  around the passage entrance  23   b.    
     An annular groove  50   e  is formed on the outer periphery of the second valve casing  50  between annular seals  52  and  53  and an annular passageway  54   c  communicating with the second fluid passage  26  is formed between the annular groove  50   e  and the peripheral surface of the second fitting hole  27 , whereby multiple passageways  54   d  connecting the passageways  54   a  and  54   c  are formed in the second valve casing  50 . 
     The second valve body  55  has, from the base end to the leading end, a piston part  55   a , a shaft base part  55   b , a shaft part  55   c , and a leading valve portion forming part  55   d . The leading valve portion forming part  55  is increased in diameter toward the leading end and the second valve portion  56  is formed on the outer periphery thereof. An annular seal  57  is fitted on the outer periphery of the piston part  55   a . The piston part  55   a  is slidably fitted in the second valve casing  50 . Stop rings  58  and  59  are fitted on the peripheral surface of the base end portion of the second valve casing  50 . Engaging with the stop rings  58  and  59 , the second valve body  55  does not move to the base end. 
     The compression coil spring  60  is fitted on the shaft base part  55   b  and shaft part  55   c  of the second valve body  55  between the piston part  55   a  of the second valve body  55  and the leading wall  50   b  of the second valve casing  50 . When the second open/close valve  65  is closed, the leading end face of the second valve body  55 , leading end face of the second valve casing  50  (the leading protrusion  50   c ), and the surface  11   a  of the clamping plate  11  are flush with each other. 
     The coupling device  15  comprises a valve body drive unit  70  as the valve body drive means for advancing only the second valve body  55  in relation to the second valve casing  50  in the male joint  25  so as to drive the first and second valve bodies  35  and  55  to the opening positions as shown in  FIG. 10  while the leading ends of the first and second valve casings  30  and  50  abut on each other as shown in  FIG. 9 . The fluid pressure supply unit  72  of the valve body drive unit  70  is shared by multiple sets of male and female joints  20  and  25  to drive the multiple first and second valve bodies  35  and  55  of the multiple sets of male and female joints  20  and  25  to the opening positions all at once. 
     As shown in  FIGS. 2 and 8  to  10 , the valve body drive unit  70  has the aforementioned piston part  55   a  provided integrally with the second valve body  55  of each male joint  25 , a fluid pressure operation chamber  71  applying a fluid pressure (for example air pressure or hydraulic pressure) to the piston part  55   a , and a fluid pressure supply unit  72  as the fluid pressure supply means for supplying a fluid pressure to the fluid pressure operation chamber  71 . 
     The fluid pressure operation chamber  71  is provided to each male joint  25 . The fluid pressure operation chamber  71  is formed in the area enclosed by the base end surface of the second fitting hole  27 , base end portion of the second valve casing  50 , and piston part  55   a . The clamping plate  11  has a fluid pressure passage  73  connecting multiple fluid pressure operation chambers  71  corresponding to multiple male joints  25  and a fluid pressure port  74  for the fluid pressure passage  73 . The fluid pressure port  74  and fluid pressure supply unit  72  are connected by a fluid pressure hose  75 . The control device  33  controls the fluid pressure supply unit  72  to supply/discharge the fluid pressure to/from each fluid pressure operation chamber  71 . 
     A fluid pressure passage  73   a  of the fluid pressure passage  73  is connected to the fluid pressure operation chamber  71  in the middle portion of the base end surface of the second fitting hole  27 . A fluid pressure passage  73   b  of the fluid pressure passage  73  is connected to the second fitting hole  27  on the outer periphery of the base end surface. It is possible to use at least one of the fluid pressure passageways  73   a  and  73   b  and omit the fluid pressure passageway  73   a  or  73   b.    
     Here, the passage entrance  23   b  formed in the leading protrusion  30   b  of the first valve casing  30  has a larger (for example approximately 1.3 times larger) diameter than the leading valve portion forming part  55   d  of the second valve body  55  and the annular width of the leading end face of the leading protrusion  30   b  of the first valve casing  30  and the annular width of the annular sealing member  61  are formed large to a certain extent. Consequently, when the leading ends of the first and second valve casings  30  and  50  abut on each other with the axes of the female and male joints  20  and  25  being shifted within a predetermined range, the valve body drive unit  70  can advance the second valve body  55  so as to drive the first and second valve bodies  35  and  55  to the opening positions and connect the female and male joints  20  and  25 . 
     Actions and advantages of the above described coupling device  15  will be described hereafter. 
     First, before the mold M 2  is fixed to the clamping plate  11 , the female and male joints  20  and  25  are separated and the first and second open/close valves  45  and  65  are closed as shown in  FIG. 8 . Then, the mold M 2  will be conveyed to be fixed to the clamping plate  11 . Here, the female and male joints  20  and  25  do not protrude from the surfaces of the mold M and clamping plate  11 . Therefore, the space between the mold M 2  and clamping plate  11  can be minimized while the mold M is moved in parallel to the fixing surface  11   a  of the clamping plate  11 . 
     Then, for fixing the mold M 2  to the clamping plate  11  in a predetermined positional relationship, the mold M 2  is moved to the clamping plate  11  as the female and male joints  20  and  25  face each other as shown in  FIG. 8 . Consequently, as shown in  FIG. 9 , the aforementioned surfaces of the mold M 2  and clamping plate  11  abut on each other and the leading ends of the first and second valve casings  30  and  50  abut on each other. In this state, the mold M 2  is fixed to the clamping plate  11 . 
     Here, since the first valve casing  30  slightly protrudes forward from the first fitting hole  22 , the leading ends of the first and second valve casings  30  and  50  steadily abut on each other. Then, the first valve casing  30  is pushed against the biasing force of the compression coil spring  34  and slightly retreated in the second valve casing  50  together with the first valve body  35  and annular member  37 . When the leading ends of the first and second valve casings  30  and  50  abut on each other, the annular sealing member  61  abuts on the leading end of the first valve casing  30  around the passage entrance  23   b . The annular sealing member  61  connects the passage entrance  23   b  of the first valve casing  30  and the passage entrance  54   b  of the second valve casing  50  in a sealed manner. 
     Then, as shown in  FIG. 10 , the fluid pressure supply unit  72  is driven so that a fluid pressure is supplied to each fluid pressure operation chamber  71 , the fluid pressure is applied to the piston part  55 , the second valve body  55  is advanced against the biasing force of the compression coil spring  60 , and the second open/close valve  65  is opened. Furthermore, when the second valve body  55  is advanced, it is inserted in the first valve casing  30  through the passage entrance  23   b . Then, the second valve body  55  pushes and retreats the first valve body  35  against the biasing force of the compression coil spring  40 , whereby the first open/close valve  45  is opened. 
     In this way, the female and male joints  20  and  25  are connected and the first and second fluid passages  21  and  26  are connected though the passageways and passage entrances  23   a  to  23   e  of the female joint  20  and the passageways and passage entrances  54   a  to  54   d  of the male joint  25 . In this state, the fluid supply/discharge unit  31  is driven so that the fluid is supplied/discharged to/from multiple first fluid passages  21  in the mold M 2 . When the fluid pressure is released from each fluid pressure operation chamber  71 , the first and second valve bodies  35  and  55  are returned by the compression coil springs  40  and  60  and the first and second open/close valves  45  and  65  are closed. In this state, the mold M 2  can be unfixed from the clamping plate  11 . 
     This coupling device  15  comprises the valve body drive unit  70  advancing only the second valve body  55  in relation to the second valve casing  50  in the male joint  25  so as to drive the first and second valve body  35  and  55  to the opening positions while the leading ends of the first and second valve casing  30  and  50  abut on each other. In this way, the valve body drive unit  70  drives only the first and second valve bodies  35  and  55  so as to open the first and second open/close valves  45  and  65  while the leading ends of the first and second valve casing  30  and  50  abut on each other, whereby the female joint  20  can be simplified in structure and downsized. Furthermore, as for the male joint  25 , a simple and small fluid pressure cylinder can be used for advancing the second valve body  55  in relation to the second valve casing  50  by means of the valve body drive unit  70 , whereby the male joint structure including the male joint  25  and fluid pressure cylinder can be simplified and downsized. 
     Hence, the space for fitting the female joint  20  and male joint  25  (male joint structure) is assured on the existing mold M 2  and clamping plate  11 . Furthermore, the valve body drive unit  70  drives only the first and second valve bodies  35  and  55  to open the first and second open/close valves  45  and  65  while the leading ends of the first and second valve casings  30  and  50  abut on each other. Therefore, the intended behavior of the coupling device  15  is assured in the configuration in which the aforementioned surface of the mold M 2  and the leading end face of the first valve casing  30  of the female joint  20  are substantially flush with each other and the aforementioned surface of the clamping plate  11  and the leading end face of the second valve casing  50  of the male joint  25  are substantially flush with each other. 
     Even in the case in which multiple sets of male and female joints  20  and  25  are provided to the mold M 2  and clamping plate  11 , the female joint  20  and male joint  25  (male joint structure) can be downsized as in this embodiment and, therefore, properly arranged. Furthermore, the total weight of the mold M 2  and multiple female joints  20  will not excessively be increased; therefore, increase in the workload of moving them can be suppressed. The total weight of the clamping plate  11  and multiple male joints  25  (male joint structure) will not excessively be increased; therefore, increase in the workload of moving them can be suppressed. 
     As described above, the aforementioned surface of the mold M 2  and the leading end face of the first valve casing  30  of the female joint  20  are substantially flush with each other and the aforementioned surface of the clamping plate  11  and the leading end face of the second valve casing  50  of the male joint  25  are substantially flush with each other, whereby the female and male joints  20  and  25  do not protrude substantively from the mold M 2  and clamping plate  11  and cause no obstruction. The mold M 2  can be fixed to the clamping plate  11  without using a conventional clamping member. Then, in conveying the mold M 2  for fixing it to the clamping plate  11 , the mold M 2  can be moved in parallel to the clamping plate  11  with the minimized space between the mold M 2  and clamping plate  11 , achieving improvement in saving the conveyance space. 
     Having a piston part  55   a  provided integrally with the second valve body  55  of the male joint  25 , a fluid pressure operation chamber  71  applying a fluid pressure to the piston part  55   a , and a fluid pressure supply unit  72  supplying the fluid pressure to the fluid pressure operation chamber  71 , the valve body drive unit  70  can securely advance the second valve body  55  in relation to the second valve casing  50 . Furthermore, the piston part  55   a  is integrated in the second valve body  55  and the fluid pressure operation chamber  71  can have a simple structure and easily be provided, ensuring that the male joint structure can be simplified and downsized. 
     Multiple sets of female and male joints  20  and  25  are provided and the fluid pressure supply unit  72  is shared by the multiple sets of female and male joints  20  and  25 . Therefore, it is unnecessary to provide as many fluid pressure supply unit  72  as the number of female joints, whereby the coupling device  15  can be simplified in structure. The first valve casing  30  of the female joint  20  is fitted in the first fitting hole  22  movably in the retreating direction and the compression coil spring  34  biasing the first valve casing  30  outward is provided, whereby errors in manufacturing the female and male joints  20  and  25  and errors in assembling them to the mold M 2  and clamping plate  11  are absorbed when the mold M 2  is fixed to the clamping plate  11 , ensuring that the leading ends of the first and second valve casings  30  and  50  abut on each other. 
     The second valve seat  51  of the male joint  25  consists of an annular sealing member  61  fitted on the leading end of the second valve casing  50  and the annular sealing member  61  abuts on the leading end of the first valve casing  30  of the female joint  20 , whereby this single annular sealing member  61  constitutes the second valve seat  51  of the male joint  25  and ensures that the leading ends of the first and second valve casing  30  and  50  abut on each other in a sealed manner. Hence, the male joint  25  can be simplified in structure (reduced in the number of parts) while these two functions are ensured. 
     Embodiment 2 
     In the coupling device of embodiment 2, the female joint is fitted on a mold as the first member and the male joint is fitted on a joint fitting member as the second member that is a platen auxiliary and fixed to the clamping plate for fixing the mold in a horizontal injection molding machine, whereby the first fluid passage in the mold and the second fluid passage in the joint fitting member are connected/disconnected when the mold is locked/unlocked to/from the clamping plate. 
     As shown in  FIGS. 11 to 15 , a coupling device  100  comprises multiple (for example six) female joints  110  fitted on the mold M 2  and multiple (for example six) male joints  115  fitted on a joint fitting member  101  fixed to the clamping plate  11  and paired with the multiple female joints  110 , whereby multiple (for example six) first fluid passages  111  in the mold M 2  and multiple (for example six) second fluid passages  116  in the joint fitting member  101  are connected/disconnected through the multiple sets of female and male joints  110  and  115  when the mold M 2  is fixed/unfixed to/from the clamping plate  11  in a predetermined positional relationship. 
     The joint fitting member  101  has an elongated block form and vertically placed on the fixing surface  11   a  of the clamping plate  11  along the side area out of the area where the mold M 2  is fixed and fastened by multiple bolts  102 . Not-shown fluid ports of the second fluid passages  116  are formed on the joint fitting member  101  and the fluid ports and fluid supply/discharge unit are connected by fluid hoses. The fluid supply/discharge unit is driven while the multiple first and second fluid passages  111  and  116  are connected, whereby a fluid is supplied/discharged to/from the multiple first fluid passages  111  in the mold M 2 . Here, the injection molding machine  1  comprising the clamping plate  11  is basically the same as in embodiment 1 and will not be described in detail. 
     The female and male joints  110  and  115  will be described in detail hereafter. 
     The female joint  110  will be described on the premise that the arrow c points to the leading end in  FIG. 12  and the male joint  115  will be described on the premise that the arrow d points to the leading end in  FIG. 12 . 
     As shown in  FIGS. 12 to 15 , the female joint  110  has a first valve casing  120  fitted in a first fitting hole  112  formed in the mold M 2  and having a first valve seat  121  in the leading end portion, a first valve body  125  fitted in the first valve casing  120  movably in the advancing/retreating direction and having in the leading end portion a first valve portion  126  abutting on the first valve seat  121  from the inside (base end side), and a compression coil spring  130  as the first biasing means for biasing the first valve body  125  toward the closing position (leading end) in relation to the first valve casing  120 . 
     The first fitting hole  112  is circular in cross-section and open on the surface of the mold M 2  (the surface facing the joint fitting member  101  when the mold M 2  is fixed to the clamping plate  11 ). A first fluid passage  111  is connected to the base end portion of the first fitting hole  112 . The aforementioned surface of the mold M 2  and the leading end face of the first valve casing  120  are substantially flush with each other and the first valve seat  121  and first valve portion  126  constitute a first open/close valve  135 . 
     The first valve casing  120  has a barrel  120   a  and a leading wall  120   b . The barrel  120   a  is fitted in the first fitting hole  112  and the leading end portion of the barrel  120   a  is screwed on and fixed to the peripheral surface of the first fitting hole  112 . An annular seal  122  is fitted on the outer periphery of the longitudinally middle portion of the barrel  120   a . The leading wall  120   b  includes the same structure as the central core part of the leading protrusion  30   b  of the first valve casing  30  in embodiment 1 and will not be described in detail. 
     A first valve body  125 , an annular member  126 , a stop ring  127 , an annular seal  128 , and a compression coil spring  130  are provided in the first valve casing  120 . They have basically the same structures as the first valve body  35 , annular member  37 , stop ring  38 , annular seal  39 , and compression coil spring  40  in embodiment 1, respectively, and will not be described in detail. 
     As shown in  FIGS. 11 to 15 , the male joint  115  comprises a casing member  140  fitted in a second fitting hole  117  formed in the joint fitting member  101 , a second valve casing  145  fitted in the second fitting hole  117  via a casing member  140  movably in the advancing/retreating direction and having a second valve seat  146  in the leading end portion, a second valve body  150  fitted in the second valve casing  145  movably in the advancing/retreating direction and having in the leading end portion a second valve portion  151  abutting on the second valve seat  146  from the outside (leading end side), and a compression coil spring  155  as the second biasing means for biasing the second valve body  150  toward the closing position (base end) in relation to the second valve casing  145 . 
     The second fitting hole  117  is circular in cross-section and has a large-diameter hole  117   a  in the leading end portion and a small-diameter hole  117   b  in the base end portion. The second fitting hole  117  is open on the surface of the joint fitting member  101  (the surface facing the mold M 2  when the mold M 2  is fixed to the clamping plate  11 ) and a second fluid passage  116  is connected to the peripheral surface of the second fitting hole  117  (large-diameter hole  117   a ). The aforementioned surface of the joint fitting member  101  and the leading end face of the second valve casing  145  are substantially flush with each other and the second valve seat  146  and second valve portion  151  constitute a second open/close valve  160 . 
     The casing member  140  has a barrel  140   a  and a leading wall  140   b . The barrel  140   a  is fitted in the large-diameter hole  117   a  of the second fitting hole  117 . The leading end portion of the barrel  140   a  is screwed on and fixed to the peripheral surface of the large-diameter hole  117   a  with the base end of the barrel  140   a  abutting on a step  117   c  at the border between the large-diameter hole  117   a  and small-diameter hole  117   b  of the second fitting hole  117 . Annular seals  141  and  142  are fitted on the barrel  140   a  in the longitudinally middle portion and in the base end portion. A circular opening  140   c  is formed in the leading wall  140   b  and an inner flange  140   d  is formed at the leading end of the leading wall  140   b . The leading end face of the casing member  140  is flush with the aforementioned surface of the joint fitting member  101 . 
     The second valve casing  145  has a barrel  145   a  and a leading protrusive barrel  145   b . The leading end portion of the barrel  145   a  is slidably fitted in the barrel  140   a  of the casing member  140 . Annular seals  147  and  148  are placed on the outer periphery of the leading end portion of the barrel  145   a . The base end portion of the barrel  145   a  is housed in the small-diameter hole  117   b  of the second fitting hole  117 . The leading protrusive barrel  145   b  is inserted in the circular opening  140   c  of the casing member  140  and slidably fitted in the inner flange  140   d.    
     A compression coil spring  165  as the second valve casing biasing means for biasing the second valve casing  145  in the retreating direction is fitted on the leading protrusive barrel  145   b  of the second valve casing  145  between the inner flange  140   d  of the casing member  140  and the barrel  145   a  of the second valve casing  145 . The second valve casing  145  does not move in the retreating direction because its base end abuts on the base end face of the second fitting hole  117 . In this state, the leading end face of the second valve casing  145  is flush with the aforementioned surface of the joint fitting member  101  and the leading end face of the casing member  140 . From this state, the second valve casing  145  can be advanced. Latched by the leading wall  140   b  of the casing member  140 , the barrel  145   a  of the second valve casing  145  does not move in the advancing direction. 
     The leading protrusive barrel  145   b  has in the leading end portion an annular recess  145   c  that is open in the leading end. An annular sealing member  166  is fitted in the annular recess  145   c . The annular sealing member  166  constitutes a second valve seat  146  and is capable of abutting on the leading end of the first valve casing  120  of the female joint  110 . 
     The second valve body  150  has, from the base end to the leading end, a piston part  150   a , a shaft base part  150   b , a shaft part  150   c , and a leading valve portion forming part  150   d . The second valve body  150  has basically the same structure as the second valve body  55  in embodiment 1. Stop rings  167  and  168  similar to the stop rings  58  and  59  in embodiment 1 are fitted in the second valve casing  145 . A compression coil spring  155  is fitted in the same manner as the compression coil spring  60  in embodiment 1. 
     The coupling device  100  comprises a valve body drive unit  170  as the valve body drive means for advancing the second valve casing  145  and second valve body  150  of the male joint  115  together while the first and second valve casing  120  and  145  closely face each other as shown in  FIG. 13  so that the leading ends of the first and second valve casings  120  and  145  abut on each other as shown in  FIG. 14  and, then, advancing only the second valve body  150  in relation to the second valve casing  145  in the male joint  115  so as to drive the first and second valve bodies  125  and  150  to the opening positions as shown in  FIG. 15 . 
     The valve body drive unit  170  has basically the same structure as the valve body drive unit  70  in embodiment 1 and has the aforementioned piston part  150   a  provided integrally with the second valve body  150  of each male joint  115 , a fluid pressure operation chamber  171  applying a fluid pressure to the piston part  150   a  and the base end of the second valve casing  145 , the aforementioned compression coil spring  155 , and a fluid pressure supply unit  172  supplying the fluid pressure to the fluid pressure operation chamber  171 . The fluid pressure operation chamber  171  is formed in the area enclosed by the small-diameter hole  117   b  of the second fitting hole  117 , base end portion of the second valve casing  145 , and piston part  150   a . A fluid pressure passageway  173  leading the fluid pressure from the fluid pressure supply unit  172  to the fluid pressure operation chamber  171  is formed in the joint fitting member  101 . 
     Here, the valve body drive unit  170  can advance the second valve body  150  so as to drive the first and second valve bodies  125  and  150  to the opening positions and connect the female and male joints  110  and  115  while the leading ends of the first and second valve casing  120  and  145  abut on each other with the axes of the female and male joints  110  and  115  being shifted within a predetermined range. 
     Actions and advantages of the above described coupling device  100  will be described hereafter. 
     In conveying the mold M 2  for fixing it to the clamping plate  11 , the mold M 2  is horizontally moved in parallel to the fixing surface  11   a  of the clamping plate  11  from the opposite side to the joint fitting member  101  using multiple rollers  105  attached to the clamping plate  11  and fixed to the clamping plate  11  in a predetermined positional relationship. 
     Here, as shown in  FIG. 13 , the first valve casing  120  of each female joint  110  and the second valve casing  145  of each male joint  115  closely face each other. A fluid pressure is supplied to the fluid pressure operation chamber  171  of the male joint  110 . First, as shown in  FIG. 14 , while maintaining their integrity with the help of the biasing force of the compression coil spring  155 , the second valve casing  145  and second valve body  150  advance together against the biasing force of the compression coil spring  165  and the leading end of the second valve casing  145  abut on the leading end of the first valve casing  120 . 
     The fluid pressure continues to be supplied to the fluid pressure operation chamber  171  while the leading ends of the first and second valve casing  120  and  145  abut on each other. The second valve body  150  advances in relation to the second valve casing  145  to open the second open/close valve  160  and the second valve body  150  is inserted in the first valve casing  120  to push and retreat the first valve body  125  against the biasing force of the compression coil spring  130  so as to open the first open/close valve  135 , 
     In this way, the female and male joints  110  and  115  are connected and the first and second fluid passages  111  and  116  are connected. When the fluid pressure is released from each fluid pressure operation chamber  171 , the second valve casing  145  and second valve body  150  are returned and retreated by the compression coil spring  155  and  165  and the first valve body  125  is returned by the compression coil spring  130 , whereby the first and second open/close valves are closed. 
     In the coupling device  100 , the second valve casing  145  of the male joint  115  is fitted in the second fitting hole  117  via a casing member  140  movably in the advancing direction, a compression coil spring  165  biasing the second valve casing  145  in the retreating direction is provided, the second valve casing  145  and second valve body  150  are advanced together when a fluid pressure is supplied to the fluid pressure operation chamber  171  while the first and second valve casings  120  and  145  closely face each other. After the leading ends of the first and second valve casings  120  and  145  abut on each other, the second valve body  120  is advanced in relation to the second valve casing  145 . Therefore, prior to connecting the female and male joints  110  and  115 , the mold M 2  is fixed to the clamping plate  11  so that the first and second valve casings  120  and  145  closely face each other. Then, the leading ends of the first and second valve casings  120  and  145  are brought to securely abut on each other and the female and male joints  110  and  115  are securely connected. Other fundamental advantages are the same as those in embodiment 1. 
     As shown in  FIG. 16 , the joint fitting member  101  can be placed horizontally and fixed to the fixing surface  11   a  of the clamping plate  11  below the area where the mold M 2  is fixed. In such a case, the mold M 2  is moved downward in parallel to the fixing surface  11   a  of the clamping plate  11  and fixed to the clamping plate  11  in a predetermined positional relationship. Then, the female and male joints  110  and  115  are connected. 
     It is possible in embodiments 1 and 2 to fit the male joint  25  or  115  on the mold M 2  and fit the female joint  20  or  110  on the clamping plate  11  or joint fitting member  101 . It is also possible to fix to the mold M 2  a not-shown joint fitting member that is a mold auxiliary similar to the joint fitting member  101  and fit the female joint  20  or  110  or the male joint  25  or  115  on this joint fitting member. 
     Embodiment 3 
     In the coupling device of embodiment 3, the female joint is fitted on the mold as the first member and the male joint is fitted on a platen as the second member for fixing the mold in a horizontal injection molding machine, whereby the first fluid passage in the mold and the second fluid passage in the platen are connected/disconnected when the mold is fixed/unfixed to/from the platen. 
     As shown in  FIGS. 17 and 18 , a horizontal injection molding machine  1 A does not have the clamping plate  10  or  11  in the horizontal injection molding machine of Embodiment 1. A fixed platen  2 A and a movable platen  3 A have multiple magnets installed for generating a magnetic adsorption force and are alternatively switched between the active state in which the magnetic adsorption force is generated and the inactive state in which the magnetic adsorption force is not generated. 
     More specifically, the same multiple magnet units  80  as in embodiment 1 are installed in the same manner as those installed in the clamping plate  11  in embodiment 1. The same male joint  25  as in embodiment 1 is fitted somewhere on the movable platen  3 A other than the area where the multiple magnet units  80  are installed (for example on one side of the movable platen  2 A) in the same manner as that fitted on the clamping plate  11  in embodiment 1. This male joint  25  and the female joint  20  fitted on the mold M 2  in the same manner as in embodiment 1 constitute a coupling device  180  of embodiment 3. Here, like the movable platen  3 A, the fixed platen  2 A also has multiple magnet units  80 . 
     The coupling device  180  has basically the same advantages as embodiment 1 and can eliminate the clamping plate  10  or  11  in embodiment 1; therefore, the horizontal injection molding machine  1 A can be simplified in structure and the molten resin injection path for injecting molten resin into the cavities of the molds M 1  and M 2  from the back of the fixed platen  2 A can be shortened as the clamping plate  10  is eliminated, whereby the molten resin in a proper molten state can be injected into the cavities of the molds M 1  and M 2 , increasing the accuracy of injection molding. 
     Embodiment 4 
     In the coupling device of embodiment 4, the female joint is fitted on the mold as the first member and the male joint is fitted on a joint fitting member as the second member that is a platen auxiliary and fixed to a platen for fixing the mold in a horizontal injection molding machine, whereby the first fluid passage in the mold and the second fluid passage in the joint fitting member are connected/disconnected when the mold is fixed/unfixed to/from the platen. 
     The horizontal injection molding machine  1 A is the same as in embodiment 3. However, as shown in  FIGS. 19 and 20 , the male joint  25  is not fitted on the movable platen  3 A and the same joint fitting member  101  as in embodiment 2 is fixed to the movable  3 A in the same manner as it is fixed to the clamping plate  11  in embodiment 2. The same male joint  115  as in embodiment 2 is fitted on this joint fitting member  101  and this male joint  115  and the female joint  110  fitted on the mold M 2  in the same manner as in embodiment 2 constitute a coupling device  190  of embodiment 4. 
     The coupling device  140  has basically the same advantages as embodiment 3 and, additionally, facilitates the provision of the male joint  110  by fixing the joint fitting member  101  to the movable platen  3 A, thereby improving versatility. 
     It is possible in embodiments 3 and 4 to fit the male joint  25  or  115  on the mold M and fit the female joint  20  or  110  on the movable platen  3 A or joint fitting member  101 . Furthermore, it is also possible to fix to the mold M a not-shown joint fitting member that is a mold auxiliary similar to the joint fitting member  101  and fit the female joint  20  or  110  or male joint  25  or  115  on this joint fitting member. 
     Modifications other than the above described matters can be made to the present invention without departing from the scope of the present invention. For example, in embodiments 2 and 4, the surface of the joint fitting member  101  can be flush with the fixing surface of the clamping plate  11  or movable platen  3 A instead of protruding from the surface of the clamping plate  11  or movable platen  3 A. Furthermore, the fluid pressure supply unit  72  or  172  can be replaced with a manually operated mechanical fluid pressure supply system. Furthermore, the number, arrangement, and structure of female and male joints can be modified as appropriate.