Abstract:
A safer safety door, provided at low cost and imposing little burden on an operator. A primary safety door with a top and a secondary safety door are provided on a clamping unit. The primary safety door and the secondary safety door abut each other at abutting portions provided on each safety door. The secondary safety door has an engaging member that swings along a guide member. The engaging member has a hinge bent in one direction. When both safety doors are closed, the primary safety door can be freely opened and closed independently. When the secondary safety door is opened, both safety doors are linked together and move as a single body. In the state where the primary and secondary safety doors are opened separately, when the primary safety door is moved to be closed, the hinge member bends and both safety doors are linked together as a unit.

Description:
The present application is based on, and claims priority from, Japanese Application Number 2007-026021, filed Feb 5, 2007, the disclosure of which is hereby incorporated by reference herein in its entirety. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a safety door device provided on a mold clamping unit of an injection molding machine. 
   2. Description of the Related Art 
   In an injection molding machine, a clamping unit moves a movable mold mounted on a movable platen against a stationary mold mounted on a stationary platen, closes the molds, and injects resin into the molds, after which the clamping unit is moved, the molds opened, and the molded article removed. When mounting the molds on the clamping unit, when performing maintenance on the clamping unit, and further, when removing the molded article manually, it is necessary to be able to access the clamping unit from the outside. However, since the clamping unit is designed to open and close the molds, there is a risk of an operator getting a hand caught in the molds. Accordingly, as a precaution a safety door is provide on the clamping unit and configured in such a way that the clamping unit can only move when the safety door has closed the clamping unit. 
   Usually, a safety door is provided on both a front side, that is, an operation side where an operator mainly operates, and a rear side opposite the front side of the clamping unit. In order to ensure safety, it is necessary to provide switches that detect opening and closing of the safety doors on both the operation side safety door and the safety door on the side opposite the operation side. In order to prevent an increase in cost brought about by providing detection switches for each of the safety doors, some injection molding machines integrate the operation side safety door and the safety door on the side opposite the operation side into a single body, thus reducing the number of detection switches. However, such a single body structure increases the mass of the safety door, which is undesirable in that the safety door is opened and closed repeatedly when removing molded articles from the mold manually and thus imposes an undue burden on the operator. 
   Consequently, in an attempt to provide safety while at the same time reducing the burden on the operator, safety doors in which the operation side safety door can be opened and closed independently of the rear door are known. 
   For example, a safety door construction is known in which a rotary shaft is provided between the operation side safety door and the safety door on the side opposite the operation side, such that, when the operation side safety door is locked, the rotary shaft cannot rotate and thus the safety door on the side opposite the operation side cannot be opened. When the operation side safety door is not locked, the operation side safety door can be freely opened and closed. However, when the safety door on the side opposite the operation side is opened, the rotary shaft rotates, opening the operation side safety door a predetermined distance only, and when the safety door on the side opposite the operation side is open the operation side safety door is always open, and further, only when the safety door on the side opposite the operation side is closed can the operation side safety door be completely closed (see, for example, JP2002-187184A). 
   Moreover, a safety door construction is also known in which brackets are projected from each of the operation side safety door and the safety door on the side opposite the operation side, respectively, the bracket from the safety door on the side opposite the operation side is disposed rearward of the bracket of the operation side safety door (on a side at which the door closes), such that, when the operation side safety door is closed the safety door on the side opposite the operation side also closes. The operation side safety door can be opened independently, but when the safety door on the side opposite the operation side is opened the operation side safety door also opens order to ensure safety (see JP55-58321U). 
   Further, an invention in which a coupling mechanism that links the operation side safety door and the safety door on the side opposite the operation side together manually, such that when the operation side safety door and the safety door on the side opposite the operation side are coupled by the coupling mechanism both safety doors move together, and when the coupling is released both doors can be freely opened and closed independently, is also known (JP64-36425A). 
   Arrangements in which, in an injection molding machine having a operation side safety door and a safety door on the side opposite the operation side, when the operation side safety door can be freely opened and closed independently, and further, when the operation side safety door is shut, the safety door on the side opposite the operation side also is always shut as well in order to provide safety, and at the same time reduce the burden on the operator, are well known as described above. However, there are drawbacks to the above-described approaches. 
   For example, in the invention described in JP2002-187184A, even when the safety door on the side opposite the operation side is wide open, because the angle of the rotary shaft does not increase beyond a certain angle, the operation side safety door does not open further than that angle, and moreover, even when the safety door on the side opposite the operation side is closed, the operation side safety door cannot be closed. 
   In addition, in the invention described in JP55-58321U, when the safety door on the side opposite the operation side is opened and the safety door on the side opposite the operation side stopped after bracket impact, even though the motion of the safety door on the side opposite the operation side is stopped the operation side safety door continues to move by inertia, such that the operation side safety door is an in uncontrolled state, and consequently, safety cannot be achieved. 
   In the invention described in JP64-36425A, if the operation side safety door and the safety door on the side opposite the operation side are linked by the coupling mechanism, both safety doors move as a single body, and consequently, safety can be achieved without entering an uncontrolled state. Further, if the coupling is released, both safety doors can each be opened and closed independently, thus reducing the burden on the operator. However, the coupling mechanism must be operated manually, and further, since the structure is such that both safety doors can open and close separately, it is necessary to provide detection switches to detect opening and closing of both safety doors in order to provide safety, which increases costs. 
   SUMMARY OF THE INVENTION 
   The present invention provides a safer safety door device of an injection molding machine without increasing costs, and further, without increasing the burden on the operator. 
   A safety door device of the present invention comprises: a primary safety door provided slidably to be opened/closed on a front side of an injection molding machine and having a first abutting member; a secondary safety door provided slidably to be opened/closed on a rear side of the injection molding machine and having a second abutting member, the first and second abutting members being abutting each other when the secondary safety door is opened so that the primary safety door opens together with the secondary safety door, and the first and second abutting members being abutting each other when the primary safety door is closed so that the secondary safety door closes together with the primary safety door; an engaging portion provided at the primary safety door; and an engaging member provided at the secondary safety door that engages/disengages with the engaging portion of the primary safety door, the engaging member being in a state unable to engage with the engaging portion when the secondary safety door is closed and being in a state able to engage with the engaging portion when the secondary safety door is opened, wherein the primary safety door and the secondary safety door are coupled with each other by engagement of the engaging member and the engaging portion when the first abutting member is brought closer to the second abutting member within a predetermined distance, with the engaging member being in the state able to engage with the engaging portion. 
   A guide member for guiding the engaging member may be provided in a sliding direction of the secondary safety door, so that the engaging member is brought into the state unable to engage with the engaging portion and the state able to engage with the engaging portion as guided by the guide member. 
   The engaging member may comprise a lever that swings as guided by the guide member and a hinge provided at a distal end of the lever to swing to a protruding position by an urging force. In this arrangement, the hinge is swung by the engaging portion to pass the engaging portion when the first abutting member is moved relative to the second abutting member in a direction to abut each other, and is not swung by the engaging portion that is passed by the hinge when the first abutting member is move relative to the second abutting member in a direction remote from each other, with the engaging member in the state able to engage with the engaging portion. 
   The engaging member may comprise a lever that swings as guided by the guide member and a projection provided at a distal end of the lever, and the engaging portion may comprise a swingable member that swings to a protruding position by an urging force. In this arrangement, the swingable member is swung by the projection to pass the projection when the first abutting member is move relative to the second abutting member in a direction to abut each other, and is not swung by the projection that is passed by the swingable member when the first abutting member is moved relative to the second abutting member in a direction remote from each other, with the engaging member in the state able to engage with the engaging portion. 
   When the secondary safety door is closed shut, the primary safety door can be freely opened and closed independently of the secondary safety door so that there is no great burden on the operator. When the secondary safety door is open, the primary safety door is always open to provide safety. Further, both the primary safety door and the secondary safety door can be opened and closed separately; alternatively, the primary safety door and the secondary safety door can be moved together as a single body. In addition, if the primary safety door is closed shut then the secondary safety door is also always closed shut, and if the secondary safety door is opened in a state in which both the primary safety door and the secondary safety door are closed shut, the primary safety door opens, and further, in this case, the primary safety door and the secondary safety door are coupled together and move as a single body. Therefore, the primary safety door, which is not being operated, does not continue to move by itself under inertia, and the operation of the primary safety door can also be controlled by operation of the secondary safety door so that safety can be achieved. 
   When either the primary safety door or the secondary safety door is operated alone and both safety doors are moved, both safety doors are always coupled together and move as a single body, so that the safety door that is not being operated never becomes uncontrollable. In addition, when only one of the safety doors is moved, the moving safety door is of course one that is being operated by the operator, and therefore safety is achieved, and thus safety is attained in any case. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1   a  and  1   b  are schematic overall views showing plan and front views, respectively, of an injection molding machine provided with a safety door according to one embodiment of the present invention; 
       FIGS. 2   a - 2   c  are structural drawings of the safety door according to one embodiment of the present invention; 
       FIGS. 3   a - 3   f  are drawings illustrating a construction of engaging means and opening and closing operations of the safety door in the embodiment; 
       FIGS. 4   a - 4   f  show states of the opening and closing operations of the safety door in the embodiment; and 
       FIGS. 5   a  and  5   b  illustrate another aspect of the engaging means of the embodiment. 
   

   DETAILED DESCRIPTION 
     FIGS. 1   a  and  1   b  are schematic overall views showing plan and front views, respectively, of an injection molding machine provided with a safety door according to one embodiment of the present invention. 
   As shown in  FIGS. 1   a  and  1   b , a clamping unit  1  and an injection unit  2  are placed on a base  3  of the injection molding machine. A safety door device  10  is provided on the clamping unit  1 . The safety door device  10  is configured so that a primary safety door  10   a  is provided on an operation side (front side) and a secondary safety door  10   b  is provided on a side opposite the operation side (rear side), in such a way that the primary safety door  10   a  and the secondary safety door  10   b  slide laterally in the drawing atop the base  3  so that the safety doors  10   a ,  10   b  can open and close. The primary safety door  10   a  is a safety door bent so as to open and close the front side and a top side. 
     FIGS. 1   a  and  1   b  show the clamping unit  1  closed. By moving the primary safety door  10   a  to the left in  FIGS. 1   a  and  1   b , the front and top are opened to enable a mold to be mounted or removed, a molded article to be removed form the mold, the clamping unit to be maintained, and so forth. In addition, by moving the secondary safety door  10   b  to the left in  FIGS. 1   a  and  1   b , the rear side is opened to similarly enable various operations to be performed on the clamping unit  1 . 
     FIGS. 2   a - 2   c  illustrate the structure of the safety door  10 , showing rear, plan, and front views, respectively, of the safety door  10 . As noted previously, the safety door  10  is composed of a primary safety door  10   a  that covers the front and the top of the clamping unit  1  of the injection molding machine and opens and closes, and a secondary safety door  10   b  that covers the rear of the clamping unit  1  and opens and closes. The primary safety door  10   a  and the secondary safety door  10   b  can be freely opened and closed independently. In addition, these two safety doors  10   a ,  10   b  can be moved together as a single body by an engaging means  11 . In  FIGS. 2   a - 2   c , both the primary safety door  10   a  and the secondary safety door  10   b  are shown partially open. 
   A guide member  12  that guides a roller  11   c  of the engaging means  11  in a direction in which the secondary safety door  10   b  opens and closes is located on the rear side of the clamping unit  1  of the injection molding machine. The guide member  12  forms a type of cam surface with respect to the roller  11   c , such that, where the secondary safety door  10   b  is closed shut, the roller  11   c  guide surface is lowered. 
   It should be noted that  14   a  is a handle for opening and closing the primary safety door  10   a  and  14   b  is a handle for opening and closing the secondary safety door  10   b . Reference numerals  15   a ,  15   b  denote transparent windows provided on the primary safety door  10   a  and the secondary safety door  10   b  for looking therethrough into the interior. In addition, reference numerals  16 ,  17  denote detection switches for detecting opening and closing of the primary safety door  10   a . That the detection switches  16 ,  17  are provided only for the primary safety door  10   a  represents an effort to reduce costs. Reference numeral  13  denotes a stationary platen cover. 
     FIGS. 3   a - 3   f  are drawings illustrating the construction of the engaging means and opening and closing operations of the safety door  10 . In addition,  FIGS. 4   a - 4   f  show states of the primary safety door  10   a  and the secondary safety door  10   b  corresponding to the opening and closing operations of the safety door  10  shown in  FIGS. 3   a - 3   f.    
   The secondary safety door  10   b  has a projection  10   b ′ bent inward from a top end of the closed side of the secondary safety door  10   b , and a notched portion  10   a ′ is provided in a top side member of the primary safety door  10   a  at a position corresponding to the projection  10   b ′ (see  FIG. 2   b ). A face of the notched portion  10   a ′ is an abutting portion (first abutting portion)  18   a  that a stopper  18   b  abuts. The stopper  18   b  (second abutting portion) that abuts the abutting portion of the primary safety door  10   a  and is made of an elastic body such as rubber is provided on the projection  10   b ′ of the secondary safety door  10   b . An engaging portion  19  that engages the engaging means  11  to move the primary safety door  10   a  and the sec as a single body is formed on the notched portion  10   a ′ of the primary safety door  10   a.    
   The engaging means  11  is composed of a lever  11   a  swingingly supported by a lever rotation supporter  11   b  provided on the projection  10   b ′ of the secondary safety door  10   b , the roller  11   c  rotatably supported at an end of the lever  11   a  and guided by the guide member  12 , and a hinge member  11   d . The hinge member  11   d , in  FIG. 3   a , is urged clockwise about a hinge center of rotation  11   e  by urging means such as a spring, such that the rotation of the hinge member  11   d  is stopped at a rotation position projecting from the lever  11   a  and the hinge member  11   d  cannot rotate any further. Accordingly, the hinge member  11   d  cannot rotate any further in the clockwise direction in  FIG. 3   a  from the protruding position shown in  FIG. 3   a , though it is capable of rotating counterclockwise against the force of the urging means such as a spring. 
     FIG. 3   a  and  FIG. 4   a  show a state in which both the primary safety door  10   a  and the secondary safety door  10   b  are closed. In this state, since the guide surface of the guide member  12  is low, the weight of the lever  11   a  and the roller  11   c  causes the lever  11   a  of the engaging member  11  to swing about the lever rotation supporter  11   b  so as to create a state in which the roller  11   c  abuts the lowered guide surface of the guide member  12  at a low position. In this state, as shown in  FIG. 3   a , the hinge member  11   d  of the engaging means  11  and the engaging portion  19  of the primary safety door  10   a  do not engage, and as shown in  FIG. 3   b  and  FIG. 4   b , the primary safety door  10   a  alone can be freely opened and closed separately. In other words, when the secondary safety door  10   b  is closed shut, the primary safety door  10   a  can be freely opened and closed separately from the secondary safety door  10   b.    
   By contrast, when the secondary safety door  10   b  is opened from the state in which both the primary safety door  10   a  and the secondary safety door  10   b  are closed shut as shown in  FIG. 3   a  and  FIG. 4   a , the stopper (second abutting portion)  18   b  pushes the first abutting portion  18   a , which is a base of the engaging portion  19   b  of the notched portion  10   a ′ of the primary safety door  10   a , so that the primary safety door  10   a  opens together with the secondary safety door  10   b . This is the state shown in  FIG. 3   c  and  FIG. 4   c . In  FIG. 3   c  and  FIG. 4   c , the roller  11   c  of the engaging means  11  moves to the high part of the guide member  12 , the lever  11   a  is pushed up, the hinge member  11   d  and the engaging portion  19  of the primary safety door  10   a  engage, and further, the engaging portion  19  moves opposite the face of the secondary safety door  10   b  and the stopper (second abutting portion)  18   b . As a result, so long as the secondary safety door  10   b  is not closed shut, if the primary safety door  10   a  is operated in the direction in which the primary safety door  10   a  opens, abutment of the engaging portion  19  and the hinge member  11  (the state shown in  FIG. 3   d ) causes the secondary safety door  10   b  to open as well. If the primary safety door  10   a  is operated in a direction in which the primary safety door  10   a  closes, the first abutting portion  18   a  that is the base of the engaging portion  19  and the stopper (second abutting portion)  18   b  abut each other (the state shown in  FIG. 3   c ) and the secondary safety door  10   b  also moves in the closing direction. 
   Conversely, if in the state shown in  FIG. 3   c  and  FIG. 4   c  the secondary safety door  10   b  is operated and the secondary safety door  10   b  is opened, the stopper (second abutting portion)  11   b  pushes the first abutting portion  18   a  of the primary safety door  10   a  (the state shown in  FIG. 3   c ), moving the primary safety door  10   a  in the opening direction. If the secondary safety door  10   b  is operated in the closing direction, then the hinge member  11   d  and the engaging portion  19  abut each other (the state shown in  FIG. 3   d ) and, since the hinge member  11  cannot rotate further in the clockwise direction from the protruding position, the hinge member  11   d  pushes the engaging portion  19  and moves the primary safety door  10   a  in the closing direction. In other words, so long as the secondary safety door  10   b  cannot be closed, if either the primary safety door  10   a  or the secondary safety door  10   b  is opened or closed, the other safety door also opens and closes, so that the primary safety door  10   a  and the secondary safety door  10   b  move as a single body and open and close. 
   When the primary safety door  10   a  is operated so as to open as shown in  FIG. 3   b  and  FIG. 4   b  from the state in which both the primary safety door  10   a  and the secondary safety door  10   b  are closed as shown in  FIG. 3   a  and  FIG. 4   a , since the engaging portion  19  is not present between the hinge member id and the stopper  18   b , the primary safety door  10   a  can be freely opened and closed independently of the secondary safety door  10   b . In addition, when the secondary safety door  10   b  is operated from the state shown in  FIG. 3   b  and  FIG. 4   b , as shown in  FIG. 3   e  and  FIG. 4   e , in a range in which the hinge member  11   d  and the engaging portion  19  do not abut each other, the secondary safety door  10   b  can be freely opened and closed independently of the primary safety door  10   a.    
   However, when the primary safety door  10   a  or the secondary safety door  10   b  is moved so that the hinge member  11   d  and the engaging portion  19  abut each other as shown in  FIG. 3   f  and  FIG. 4   f  from the state shown in  FIG. 3   e  and  FIG. 4   e , since the hinge member  11   d  rotates in the counter-clockwise direction, the hinge member  11   d  is pushed over by the engaging portion  19 , allowing the engaging portion  19  to pass and entering the states shown in  FIGS. 3   d  and  4   d  or in  FIG. 3   c  and  FIG. 4   c . After reaching this state, as described above, the primary safety door  10   a  and the secondary safety door  10   b  open and close as a single body until both are closed shut. 
   Thus, as described above, the primary safety door  10   a  and the secondary safety door  10   b  can be moved separately and opened and closed, and the primary safety door  10   a  and the secondary safety door  10   b  can be moved as a single body and the doors opened and closed. When the doors are moved as a single body, the primary safety door  10   a  and the secondary safety door  10   b  are coupled by the engaging means  11 , and therefore when the safety door being operated is stopped the other safety door also stops, such that the safety door on the side that is not being operated does not continue to move under inertia and therefore safety can be achieved. 
   It should be noted that although in the embodiment described above the hinge member  11   d  is provided on the engaging means  11  and the engaging portion  19  is provided on the primary safety door  10   a , alternatively these may be reversed, with the hinge member  11   d  provided on the primary safety door  10   a  and the engaging portion  19  provided on the engaging means  11 . 
     FIGS. 5   a  and  5   b  illustrate another aspect of the engaging means of the embodiment, that is, an example of the reversal described above. A swingable member  21  similar to the hinge member  11   d  described above is provided on the primary safety door  10   a , with a projection  22  that engages the swingable member  21  provided on the engaging means  11 . Then, the swingable member  21  is urged to the state shown in  FIG. 5   a , either under its own weight or by urging means such as a spring. Although the swingable member  21  can rotate about an axis  21   a  in a direction indicated by an arrow in  FIG. 5   a , it cannot rotate in the reverse direction. As a result, as shown in  FIG. 5   b , when the primary safety door  10   a  and the secondary safety door  10   b  are moved and the swingable member  21  moves from right to left in the drawing with respect to the projection  22 , the swingable member  21  rotates and rides up over the projection  22 . If the swingable member  21  rides up over the projection  22  and gets between the projection  22  and the secondary safety door  10   b  (the stopper  18   b ), then the swingable member  21  does not rotate even when it abuts the engaging portion  22  (the projection  22 ) and thus the primary safety door  10   a  and the secondary safety door  10   b  are coupled together and move as a single body. The remaining operations are the same as those described above with reference to  FIGS. 3   a - 3   f .