Abstract:
A work transfer apparatus configured to move a work to an operating position while transferring the work by a conveyor, perform predetermined processing at the operating position, and discharge a processed work, the work transfer apparatus comprising an ejector moving the work independently from the conveyor; and a stopper stopping the work at the operating position, wherein the work processed by the predetermined processing is discharged by the ejector, and a work to be moved to the operating position next by the conveyor is stopped at the operating position by the stopper.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
   The present document is based on Japanese Priority Document JP 2003-400331, filed in the Japanese Patent Office on Nov. 28, 2003, the entire contents of which being incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a work transfer apparatus and, more particularly, to a work transfer apparatus which is constructed to move a work to an operating position while transferring the work by means of a conveyor, performs predetermined processing at this operating position, and discharges the processed work. 
   2. Description of Related Art 
   Component mounters are widely used in order to mount components on circuit boards and fabricate electronic circuits. A component mounter is provided with a suction nozzle at one end of a mount head, and causes this suction to attract a component by suction and moves the suction nozzle to a position above a predetermined mounting position on a circuit board by moving the suction nozzle in the X-axis and Y-axis directions relative to the circuit board. Then, the component mounter moves the suction nozzle down toward the circuit board, and mounts the attracted component on the circuit board at a predetermined position thereof. 
   This component mounter needs to sequentially transfer circuit boards to a mounting position below the mount head, and is provided with a board transfer system for this purpose. Board transfer systems are generally classified into two kinds: that is to say, a type which performs component mounting by moving the position of a board together with a conveyor, as represented by a rotary machine, and a type which performs component mounting with a board fixed in position. However, in the first type as well, since boards connected to conveyors fixed at preceding and succeeding positions need to be replaced when boards are to be replaced, the transfer of boards is under the same conditions except the time necessary for this connection is added. 
   As described above, a conveyor for transferring circuit boards on which components are to be mounted in the component mounter is made of three kinds of conveyors which are a conveyor provided at a component mounting position and conveyors provided at positions preceding and succeeding the component mounting position. The outline of operation to be started during the state in which the next board is waiting while components are being mounted on a board will be described below. 
   a. After the mounting of components on a board has been completed, the board is released from a clamp, a backup, positioning pins and the like. 
   b. The conveyor provided at the component mounting position starts to move, and the board on which the components have been mounted starts to move. 
   c. When it is detected that the rear end of the board has come out of the conveyor provided at the component mounting position, a stopper moves upward. 
   d. After it is confirmed that the stopper has moved up, the conveyor preceding the component mounting position is started to initiate loading the next board. 
   e. Before the board reaches the stopper, the conveyor is decelerated by means of a sensor, a timer and the like, and the board is made to stop in the state of being lightly pressed against the stopper and the conveyor is also made to stop. 
   f. A positioning pin is moved upward to perform clamping and backup, thereby completing the replacement of the boards. 
   A beam-transfer board transfer system which is said to be shorter in board replacement time than the above-mentioned board transfer system made of conventional conveyors are disclosed in, for example, Japanese Laid-Open Patent JP-A-6-336351 and Japanese Laid-Open Patent JP-A-2-229499. This system is shorter in the time required for replacement of boards than the above-mentioned conveyor system. Similarly to the conveyor system, this beam-transfer system is provided with three kinds of conveyors. Incidentally, a conveyor provided at an intermediate mounting position only supports a board and generally does not have the ability to move a board autonomously. The beam-transfer system has a stroke equal to a maximum of the length of a board in the flowing direction of boards, and includes a beam mechanism having two board feed claws. The outline of operation to be started during the state in which the next board is waiting while components are being mounted on a board will be described below. 
   a. After the mounting of components on a board has been completed, the board is released from a clamp, a backup, positioning pins and the like. 
   b. Two board feed claws are inserted into a position where they can press the rear end of the board on which the components have been mounted and the rear end of the next board, by a method such as rotating a beam provided outside a conveyor. 
   c. The beam starts to move in the flowing direction of boards, and discharges the board on which the components have been mounted, from a component mounting area, and at the same time completes the operation of transferring the next board to a component mounting position. 
   d. A positioning pin is moved upward, and while the positioning pin is being made to perform clamping and backup, the claws are retracted and the beam returns to its original position, whereby the replacement of the boards is completed. 
   This beam-transfer system is considered to be theoretically capable of completing replacement of boards in the shortest time because both boards are moved at the same time. However, as shown by the fact that the beam-transfer system is not used as a normal system, the beam-transfer system has a number of disadvantages. The disadvantages are as follows. 
   a. In the case where discharging and loading cannot be performed at the same time, the discharging of a board on which components are mounted is first completed, and after a beam has been returned, claws have to be inserted after the next incoming board. As a result, there are cases where the beam-transfer system becomes slower than ordinary systems. 
   b. The beam-transfer system has the disadvantage of being large sized and difficult to install, for reasons such as: since two claws are integrated in the form of being separated from each other by a distance equal to a maximum board length, insertion and retraction of the claws is necessary and the beam has a stroke equal to a maximum board length. 
   c. Since two boards need to be pressed by the beam at the same time, the position of the claws needs to adjusted according to the size of boards. 
   The above-mentioned problem a in particular may be a fatal disadvantage even if the demerits of the other problems are accepted in order to adopt the beam-transfer system to shorten component replacement time.
     [Patent Document 1] Japanese Patent Application publication (KOKAI) No. Hei 6-336351   [Patent Document 2] Japanese Patent Application publication (KOKAI) No. Hei 2-229499   [Patent Document 3] Japanese Patent Application publication (KOKAI) No. Hei 11-163595   [Patent Document 4] Japanese Patent Application publication (KOKAI) No. Hei 3-214798   [Patent Document 5] Japanese Patent Application publication (KOKAI) No. Hei 4-291800   [Patent Document 6] Japanese Patent Application publication (KOKAI) No. 2001-144494   

   SUMMARY OF THE INVENTION 
   It is desirable to provide a work transfer apparatus which is capable of reducing work replacement time. 
   Further it is desirable to provide a work transfer apparatus which is constructed to solve the disadvantages of beam-transfer systems. 
   Further it is desirable to provide a work transfer apparatus which is capable of introducing the next work even if an ejector does not return to its original position in the case where discharging and loading of works cannot be performed at the same time. 
   Further it is desirable to provide a work transfer apparatus which is capable of efficiently performing replacement of works even if the stroke of an ejector is short. 
   Further it is desirable to provide a work transfer apparatus which is constructed so that the position of an ejector need not be adjusted, irrespective of the dimension of each individual work in the transfer direction thereof. 
   The above and other objects of the invention of the present application will become apparent from the following description of the technical idea of the present invention and a mode for carrying out the present invention. 
   According to an embodiment of the present invention, there is provided a work transfer apparatus which is constructed to move a work to an operating position while transferring the work by means of a conveyor, perform predetermined processing at the operating position, and discharge the processed work, the work transfer apparatus including: 
   an ejector moving the work independently from the conveyor; and 
   a stopper stopping the work at the operating position, wherein 
   the work processed by the predetermined processing is discharged by the ejector, and 
   a work to be moved to the operating position next by the conveyor is stopped at the operating position by the stopper. 
   The discharging speed at which the work processed by the predetermined processing is discharged by the ejector may be set to be larger than the moving speed of the next work to be moved to the operating position by the conveyor. In addition, the discharging speed at which the work processed by the predetermined processing is discharged by the ejector may be made larger than the speed of transfer of works by the conveyor so that a space is formed between the processed work and the next work to be processed and the stopper is inserted into the space. In addition, the transfer speed of the next work to be processed may be accelerated and decelerated independently by the conveyor so that the next work is made to stop by coming into abutment with the stopper. In addition, the ejector maybe supported for free movement on a rail disposed to extend in the running direction of the conveyor and be moved on the rail by reciprocating motion of a belt, and the rail may be displaced in a direction crossing the conveyor by an actuator so that the ejector is projected at a position where the ejector engages with the work. In addition, the stopper may be disposed at a predetermined position in the transfer path of a work moved by the conveyor, and the stopper may be displaced in a direction crossing the conveyor by the actuator so that the stopper is projected at a position between the stopper comes into abutment with the work. 
   According to another embodiment of the present invention there is provided a work transfer apparatus which is constructed to move a work to an operating position while transferring the work by means of a conveyor, perform predetermined processing at the operating position, and discharge the processed work, the work transfer apparatus including: 
   an ejector for moving the work independently from the conveyor; and 
   a stopper for stopping the work moved independently from the conveyor and transferred to the operating position, wherein 
   the work processed by the predetermined processing is discharged by the ejector, and 
   the stopper is moved between the work processed by the predetermined processing and a work next to be transferred to the operating position to stop the work next to be transferred to the operating position at a predetermined operating position. 
   The ejector and the stopper may be made to move at mutually independent speeds. In addition, the ejector and the stopper may be respectively supported for free movement on rails disposed to extend in the running direction of the conveyor and are respectively moved on the rails by reciprocating motion of belts, and the respective rails may be displaced in directions crossing the conveyor by actuators so that the ejector and the stopper are respectively projected at positions where the ejector and the stopper engage with the work. In addition, the work may be a circuit board, and components may be mounted on the circuit board at the operating position. 
   According to another embodiment of the present invention there is provided a work transfer apparatus which is constructed to move a work to an operating position while transferring the work by means of a conveyor, perform predetermined processing at the operating position, and discharge the processed work, and the work transfer apparatus includes an ejector for moving the work independently from the conveyor, and a stopper for stopping the work at the operating position, and is constructed to stop a work next to be moved to the operating position by the conveyor at the operating position. 
   According to the work transfer apparatus, while the work processed by the predetermined processing is being discharged by the ejector, the work next to be processed can be introduced by the conveyor, and it is possible to approximately accurately position the next work at the operating position by stopping the conveyor introduced at the operating position. 
   According to another embodiment of the present invention there is provided a work transfer apparatus which is constructed to move a work to an operating position while transferring the work by means of a conveyor, perform predetermined processing at the operating position, and discharge the processed work, and the work transfer apparatus includes an ejector for moving the work independently from the conveyor, and a stopper for stopping the work moved independently from the conveyor and transferred to the operating position, the work processed by the predetermined processing being discharged by the ejector, and the stopper being moved between the work processed by the predetermined processing and a work next to be transferred to the operating position to stop the work next to be transferred to the operating position at a predetermined operating position. 
   According to the work transfer apparatus, the work processed by the predetermined processing is discharged by the ejector, and in addition, a work next to be processed is introduced by the conveyor and the work is independently moved and brought into abutment with the stopper on standby, whereby the next work can be stopped at the predetermined operating position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become more apparent from the following description of the presently preferred exemplary embodiment of the invention taken in conjunction with the accompanying drawing, in which: 
       FIG. 1  is a front view showing an entire configuration of a mounter; 
       FIG. 2  is a plain view showing, partially broken out, a mounter; 
       FIG. 3  is a side view showing a part of a mounter; 
       FIG. 4 , consisting of  FIGS. 4A to 4C , is a plain view showing a part of a different apparatus. 
       FIG. 5 , consisting of  FIGS. 5A to 5B , is a plain view showing a part of a different type of a board transfer apparatus. 
       FIG. 6  is a front view showing a part of a mechanism for moving and projecting of an ejector; and 
       FIG. 7  is a cross-sectional view showing a mechanism for lifting of a stopper. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Embodiments of the present invention will be described below with reference to  FIG. 4 .  FIG. 4  shows a mechanism and a method for simultaneously moving a circuit board  19   a  on which components are mounted and a circuit board  19   b  on which components are to be mounted next, and these mechanism and method use an ejector  35  which moves together with conveyors  31 ,  32  and  33 , to realize the maximum advantage of beam transfer; that is to say, the state in which even if the incoming board  19   b  and the outgoing board  19   a  are simultaneously moved, no contact occurs at all between the boards  19   a  and  19   b . In addition to this status, even in the case of simultaneous activation, the ejector  35  is moved and stopped ahead of the incoming board  19   b , or a stopper  37  is lifted. 
   The incoming board  19   b  is transferred by being accelerated and decelerated independently by the conveyors  31  and  32 , and realizes the state of abutting on the stopper  37  which is stopped. Accordingly, even if simultaneous activation is not performed and the incoming board  19   b  comes in late, no losses occur at all unlike the case of beam transfer, whereby it is possible to realize a system capable of constantly executing processing at maximum speed even in terms of either loading or discharging. 
   This system having the belt conveyors  31 ,  32  and  33  is further provided with an actuator  36  which moves in the flowing direction of the boards  19   a  and  19   b . The ejector  35  is attached to the actuator  36 , and until the board  19   a  having components mounted thereon is discharged, the ejector  35  is lifted in the space between the board  19   a  having components mounted thereon and the board  19   b  on which components are to be mounted next, so that the ejector  35  can act on the two boards  19   a  and  19   b . In addition, until the ejector  35  placed on the actuator  36  discharges the board  19   a  having components mounted thereon, the ejector  35  is lifted in the space between the board  19   a  having components mounted thereon and the board  19   b  on which components are to be mounted next, and is placed in abutment with both boards  19   a  and  19   b.    
   Then, the ejector  35  is combined with the actuator  36  to realize the start of simultaneous movement of the board  19   a  having components mounted thereon and the board  19   b  on which components are to be mounted next. Namely, the ejector  35  is moved by the actuator  36  so as to be moved and stopped at its original position, i.e., a position where the board  19   b  on which components are to be mounted next is to be stopped (refer to  FIG. 4B ). 
   The ejector  35  is moved by the actuator  36  at a speed faster than the conveyors  31 ,  32  and  33 . Then, when the ejector  35  presses the board  19   a  furthest to a position which the stopper  37  can be lifted, the stopper  37  is lifted. The reason why the stopper  37  can be lifted without the risk of thrusting up the incoming board  19   b  is that the acceleration and the maximum speed of the ejector  35  are higher than those of the conveyors  31 ,  32  and  33  so that the ejector  35  moves ahead of the incoming board  19   b  to form a space in which the stopper  37  can be lifted. In addition, there is also a method of adjusting the length of the ejector  35  in the moving direction as well as the speed of the ejector  35  to lift the stopper  37  within a time during which the width of the ejector  35  is passing through a position lateral to one side of the stopper  37 . In this case, no limitations are imposed on the relationship in speed between the conveyors  31 ,  32  and  33  and the ejector  35 . 
   How to handle the flowing direction of the conveyors will be considered below. In the case where the conveyors flow from the right to the left in  FIG. 4 ; that is to say, the origin of the circuit boards  19   a  and  19   b  is located at the right end, if these boards  19   a  and  19   b  are small sized, the stopper  37  is brought into the state in which when the next incoming board  19   b  reaches the stopper  37 , the board  19   a  to be discharged at this time is not yet moved out of a component mounting area and the stopper  37  is forced to wait without being permitted to effect a backup or the like. To prevent the occurrence of this state, a system can be added which separates the two boards  19   a  and  19   b  from each other and presses the outgoing board  19   a  out of the component mounting area when the stopper  37  is to be lifted and stopped. Even if the boards  19   a  and  19   b  are small sized, the ejector  35  continues to move even after having passed through the position lateral to the one side of the stopper  37 , and discharges the outgoing board  19   a  from a board positioning area, whereby losses can be minimized. 
   On the other hand, in the case where the conveyors flow in the opposite direction to that of  FIG. 4  from the left to the right; that is to say, the origin of the boards is located at the left end, at the time when the stopper  37  reaches its stop position, the board  19   a  is previously discharged from the component mounting area, so that no measures are necessary. In addition, at the time when the stopper  37  is to be lifted, the outgoing board  19   a  is previously discharged from the component mounting area, so that no measures are necessary. 
   A method of minimizing the loading time of the board  19   b  on which components are to be mounted next will be described below. In the ordinary board transfer system mentioned above as the related art, it is also desired to move the boards fully fast, but the boards must be brought into abutment with the stopper  37  with a fully small impact. However, these contradictory problems: fast speed and small impact, can be coped with by decelerating the conveyors by means of a sensor or a timer. Accordingly, in the mode for carrying out the present invention as well, a method similar to this method is used to achieve the time minimizing method. 
   The acceleration and deceleration of the incoming board  19   b  is performed by friction between the conveyors  31  and  32  and the board  19   b . The coefficient of friction between the conveyors  31  and  32  and the board  19   b  is approximately 0.3. This coefficient of friction is a value which allows a slip to occur no matter how much the acceleration of the conveyors  31  and  32  is increased, and can only realize an acceleration of approximately 0.3 G. This fact means, however, that the maximum acceleration of 0.3 G can be used as long as the acceleration of the conveyors is set to 0.3 or higher. Although the coefficient of friction is set to 0.3 in this discussion, this value is an actually measured value of a certain board, which should not be deemed to be a highly universal value. 
   For this reason, consideration has been given to a method of calculating a coefficient of friction from the state of acceleration and calculating deceleration starting time so that the incoming board reaches a collideable speed immediately before colliding with the stopper. Basically, after a conveyor is activated with the incoming board placed at a constant position, an acceleration of 0.5 G or higher is given to this conveyor, and a coefficient of friction or an acceleration is calculated back from the time taken for the conveyor to reach a sensor  38  placed at an appropriate distance of, for example, 50 mm. An appropriate deceleration starting time is calculated from this calculation and is used as a timer, whereby it is possible to realize board loading which takes no wasted time. 
   According to this mode, it is possible to greatly reduce time taken to substitute the board  19   a  on which components are mounted for the board  19   b  on which components are to be newly mounted, and it is possible to reduce the tact time necessary for a mounter merely by adding a small system. For example, it is possible to realize a 12% improvement in a mounter having a cycle time of, for example, 30 seconds. 
   EXAMPLES 
     FIGS. 1 to 3  show the entire component mounting device according to an example of the present invention. This component mounting device includes a base unit  12 , a support  13  for supporting the base unit  12 , four pillars  14  respectively uprightly disposed at positions close to widthwise ends of longitudinal opposite ends for receiving the support  13  in the longitudinal direction thereof, beams  15  each supported in the form of being bridged between the top ends of two of the pillars  14  spaced apart from each other in the longitudinal direction along the lengthwise direction of the support  13 , a head mounting beam  16  disposed to be bridged between the beams  15  in a suspended form, a tool head  17  suspended from the head mounting beam  16 , and a plurality of suction nozzles disposed on the tool head  17 . In  FIGS. 1 and 2 , the direction indicated by an arrow X is called longitudinal direction or X-axis direction, while in  FIGS. 2 and 3 , the direction indicated by an arrow Y is called widthwise direction or Y-axis direction. 
   A widthwise central area on the top surface of the base unit  12  is defined as a work-placing section in which a work such as a board  19  is to be placed, and fixing means  20  for fixing the circuit board  19  is disposed in the work-placing section, and the positioning of the board  19  as well as the holding of the position of the board  19  is effected by the fixing means  20 . Two boards  19  are disposed in the work-placing section in the state of being spaced apart from each other by a predetermined distance in the longitudinal direction. 
   Guide rails  21  are respectively fixed to the bottom surfaces of the beams  15  in such a manner to extend in the X-axis direction. Guided members  22  which are respectively fixed to the top surface of the head mounting beam  16  at the opposite ends thereof are slideably engaged with the respective guide rails  21 , whereby the head mounting beam  16  is supported for movement on the beams  15  along the X axis. Driving means which is not shown is provided between the head mounting beam  16  and the beams  15  so that the head mounting beam  16  runs by itself with respect to the beams  15 . 
   The tool head  17  is provided on the head mounting beam  16  in a suspended form, and this tool head  17  is supported for movement in the Y-axis direction with respect to the head mounting beam  16 . The tool head  17  is constructed to be moved in the Y-axis direction by the rotation of a ball screw provided in the inside of the head mounting beam  16 . 
   The tool head  17  is freely movable in each of the X and Y directions by the X-axis movement of the head mounting beam  16  with respect to the beams  15  and the Y-axis movement of the tool head  17  with respect to the head mounting beam  16 . 
   The rotating spindle of the tool head  17  is disposed in the state of being inclined with respect to the vertical direction, so that the bottom end of the tool head  17  is displaced forwardly. In addition, the tool head  17  is freely rotatable in the forward and reverse directions. 
   The tool head  17  has twelve suction nozzles  18  circumferentially spaced apart from each other at equal intervals around a section close to its periphery, and the axes of the suction nozzles  18  are fixed to be inclined with respect to the rotating axis of the tool head  17 . The suction nozzles  18  are inclined in the direction in which the top ends of the respective suction nozzles  18  become closer to the rotating axis of the tool head  17 , and the twelve suction nozzles  18  are disposed to broaden toward their bottom ends with respect to the tool head  17  as a whole. 
   The suction nozzles  18  are supported for movement along their respective axes with respect to the tool head  17 , and when the suction nozzles  18  are positioned at an operating position which will be described later, the suction nozzles  18  are moved down by being pressed from above by pressure means which will be described later. 
   From among these suction nozzles  18 , a suction nozzle  18  which is positioned at the rear-end side of the tool head  17  and at the right end in  FIG. 1  has an axis directed in the vertical direction, and the position of the rear-end side of the axis corresponds to the operating position. Suction or release of chip components  23  is performed by the suction nozzle  18  positioned at the operating position and directed in the vertical direction. 
   A plurality of kinds of chip components  23  are mounted on one circuit board  19 , but since suction and mounting of these different chip components  23  cannot be performed by a single kind of suction nozzle  18 , a plurality of kinds of suction nozzles  18  are provided so that suction and mounting of different components is performed by optimum suction nozzles. 
   The suction nozzles  18  are connected to an air compressor which is not shown, and the tip of the suction nozzle  18  positioned at the operating position is switched to negative or positive pressure at a predetermined timing, whereby suction or release of the chip component  23  is performed at the tip. 
   An area in which to mount the chip components  23  for the board  19  positioned and held by the fixing means  20  constitutes a component mounting area M. 
   Forty component supply units  24  are disposed on each of the right and left sides of the component mounting area M, and a multiplicity of chip components  23  of the same kind are housed in each of the component supply units  24  and these chip components  23  are supplied to the suction nozzles  18  as required. In this description, reference is made to a construction in which the component supply units  24  are disposed on the right and left sides of the component mounting area M, but the present invention can also be applied to a construction in which the component supply units  24  are disposed on only one of the right and left sides of the component mounting area M. 
   Different kinds of chip components  23  are housed in the respective component supply units  24 , and one of the suction nozzles  18  and one of the component supply units  24  are selected according to which position on the board  19  corresponds to a chip component  23  to be mounted, and the chip component  23  is attracted to the suction nozzle  18  by suction. 
   Component supply ports  25  of the respective component supply units  24  are disposed in parallel with the right and right sides of the fixing means  20 , and the chip components  23  disposed in the respective component supply ports  25  are attached to the suction nozzles  18  by suction. Accordingly, an area in which these multiplicity of component supply ports  25  are arranged constitutes an area in which the chip components  23  are to be caught by suction. The area is referred to as a component supply area S. 
   The tool head  17  is constructed so that the suction nozzle  18  positioned at the operating position is moved in a component supply area S, the component mounting area M, and in an area connecting these areas S and M. 
   The tool head  17  first moves to a position above the component supply area S, and then sequentially attracts predetermined ones of the chip components  23  by suction from the twelve suction nozzles  18  provided on the tool head  17 . After that, the tool head  17  moves to the component mounting area M, and sequentially mounts the components attracted to the suction nozzles  18  onto the board  19  at predetermined positions thereof while adjusting its moving position in the X-axis direction and in the Y-axis direction. By repeating this operation, the chip components  23  are mounted on the board  19 . 
   A transfer apparatus for the boards  19  which is disposed along the transfer path of the boards  19  in this mounter will be described below with reference to  FIG. 4 . This transfer apparatus is provided with a pair of loading-side conveyors  31  disposed on the opposite sides, a pair of right and left conveyors  32  disposed at a processing position, and a pair of discharging-side conveyors  33 . An actuator  36  provided with the ejector  35  is provided between the conveyors  32  disposed at the processing position. Furthermore, the stopper  37  is disposed on one side of the conveyors  32  at the forward ends thereof, and the sensor  38  is disposed on the inlet side of the conveyors  32 . 
   A mechanism for moving and lifting the ejector  35  will be described below with reference to  FIG. 6 . A pair of cylinders  46  are respectively disposed at longitudinal front and rear positions on a frame  45  disposed approximately in parallel with the conveyors  32 , and a rail  47  is supported by the output-end sides of these cylinders  46 . A slider  48  is slideably secured by the rail  47 . The slider  48  is connected to a belt  51  passed between pulleys  49  and  50 . 
   Accordingly, when the belt  51  is driven, the slider  48  is reciprocally moved between the right and the left sides as viewed in  FIG. 6 . When the cylinders  46  are operated, the rail  47  is moved upward and downward as a whole. Accordingly, the slider  48  supported on the rail  47  is moved upward and downward, and the ejector  35  secured to the slider  48  is also moved up and down. 
   A mechanism for lifting the stopper  37  will be described below with reference to  FIG. 7 . An upright guide  55  is secured to the frame, and a movable block  56  is upwardly and downwardly slideably supported by this upright guide  55 . An arm  58  is secured to the movable block  56 , and the arm  58  is connected to a rod  60  of a cylinder  59 . 
   Accordingly, when the cylinder  59  is operated, the movable block  56  is moved upward or downward via the rod  60 , and the stopper  37  supported on the top end of the movable block  56  is moved between a position where the stopper  37  interferes with the board  19  and a position where the stopper  37  is retracted from the board  19 . 
   As described above, the present embodiment is a board transfer system which is provided with the transfer belt conveyors  31 ,  32  and  33  divided into three parts in the transfer direction of the boards  19   a  and  19   b  and includes the ejector  35  disposed on the actuator  36  constructed to move in the flowing direction of the boards  19   a  and  19   b , and the incoming-board stopper  37 . This board transfer system has the advantage of increasing the productivity of facilities because the incoming board  19   b  and the outgoing board  19   a  can be simultaneously loaded and discharged. 
   In the present embodiment in particular, as shown in  FIG. 4B , the ejector  35  discharges the outgoing board  19   a  while moving the outgoing board  19   a  ahead of the incoming board  19   b , and after that the incoming-board stopper  37  is projected upward. As shown in  FIG. 4C , the incoming board  19   b  is independently decelerated and accelerated by the conveyors  31  and  32 , and transfer acceleration is calculated by means of the sensor  38  and the board  19   b  is made to collide with the stopper  37  at an optimum speed. In this embodiment, since a transfer mechanism for the incoming board  19   b  is independent, even if the incoming board  19   b  enters late, no losses occur at all, it is possible to realize a system capable of constantly executing processing at maximum speed even in terms of either the discharging of the board  19   a  or the loading of the board  19   b.    
   More specifically, as shown in  FIG. 4 , the actuator  36  which is driven in the flowing direction of the boards  19   a  and  19   b  is added to the board transfer belt conveyors  31 ,  32  and  33  divided into three parts in the transfer direction. The ejector  35  is disposed on the actuator  36 , and the ejector  35  is projected in the space between the outgoing board  19   a  and the incoming board  19   b . The projection and retraction of the ejector  35  is performed by the pair of cylinders  46  shown in  FIG. 6 , and the movement of the ejector  35  is performed by the belt conveyor  51 . 
   As shown in  FIG. 4B , the actuator  36  causes the ejector  35  and the outgoing board  19   a  to move at a faster acceleration and speed than those of the conveyors  32  and  33 , and when this ejector  35  transfers the outgoing board  19   a  to a position where the stopper  37  of the incoming board  19   b  can be moved upward, the stopper  37  is moved upward. The upward movement of the stopper  37  is performed by moving the movable block  56  on the upright guide  55   in  the upward direction by means of the cylinder  59  shown in  FIG. 7 . 
   The reason why the stopper  37  can move upward without interfering with the incoming board  19   b  is that since the speed and the acceleration of the ejector  35  are higher than those of the conveyors  31  and  32 , the ejector  35  can separate the incoming board  19   b  from the outgoing board  19   a  and ensure a space enough for the stopper  37  to move upward in. 
   Otherwise, the width of the ejector  35  in the moving direction thereof and the speed of the ejector  35  may be adjusted to allow the stopper  37  to move upward within the time during which the ejector  35  is passing through the position lateral to the stopper  37 . 
   In addition, if the incoming board  19   b  is made to stop at a fixed position as shown in  FIG. 4A  and measurement is performed on the time required for the incoming board  19   b  to reach the sensor  31  disposed at an appropriate distance while the conveyors  31  are being operated at not lower than a certain acceleration, the transfer acceleration of the board  19   b  can be calculated. By setting an appropriate board transfer speed deceleration timer which the incoming board  19   b  reaches a collideable speed immediately before colliding with the incoming-board stopper  37  on the basis of that calculation, it is possible to realize board loading free of wasted time. 
   Another embodiment will be described below with reference to  FIG. 5 . This embodiment is constructed so that not only the ejector  35  but also the stopper  37  is moved by an actuator  42 . Namely, as shown in  FIGS. 5A and 5B , separation of the two boards  19   a  and  19   b  is performed by the ejector  35  and the stopper  37  when both the ejector  35  and the stopper  37  are positioned between the outgoing board  19   a  and the incoming board  19   b . In this case, the stopper  37  functions as a stopper for the incoming board  19   b  and is positioned to stop the incoming board  19   b  at the operating position as shown in  FIG. 5B . Then, the outgoing board  19   a  is discharged by the ejector  35 . This construction provides the merit of removing limitations from the mutual relationship in acceleration and speed between the conveyors  31 ,  32  and  33  and the two kinds of actuators  36  and  42 . 
   Although the invention of the present application has been described with reference to the mode for carrying out the invention as well as the embodiments, the present invention is not limited to any of the modes for carrying out the invention and the embodiments, and various modifications can be made without departing from the scope of the technical idea of the invention included in the present application. For example, although the above-mentioned mode is related to transfer of circuit boards in a component mounter, the present invention can be widely used for transfer of various other works. The construction of the actuator shown in  FIG. 6 , the lifting mechanism for the stopper shown in  FIG. 7  and the like can be variously changed in design to meet various objects.