Abstract:
A gripping device for gripping an object has a vacuum gripper; a magnet disposed within the vacuum gripper and moveable between a gripping position and a retracted position; gripping vacuum for moving the magnet to the gripping position; and release for moving the magnet to the retracted position.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates generally to gripping devices, and more particularly to gripping devices for gripping and lifting an object.  
         [0003]     2. Description of the Related Art  
         [0004]     Another gripping device is disclosed in U.S. Pat. No. 4,121,865. In this device, a permanent magnet is connected to a piston that can move in a cylinder. This piston can be moved by compressed air against the force of a spring. For this purpose, a compressed air line is connected to the cylinder. Furthermore, a vacuum line is connected to the vacuum chamber. This reference is hereby incorporated by reference in full.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention teaches certain benefits in construction and use which give rise to the objectives described below.  
         [0006]     The present invention provides a gripping device that includes a means of producing a vacuum and the means of blowing air in a single apparatus that can produce a vacuum as well as that can blow air. The device is connected to the vacuum chamber as well as to the pressure chamber. Because of this, it is possible for an object to be gripped as well as pushed away with one device. Preferably, the apparatus is a pump that works in two directions or a venturi with a blowing function.  
         [0007]     A favourable embodiment of the gripping device according to the invention is characterized in that the vacuum inlet as well as the air inlet are connected to one passage that is connected to the apparatus. Because of this, only one line has to be connected to the apparatus, which line is connected to the passage at its other end.  
         [0008]     A further favourable embodiment of the gripping device according to the invention is characterized in that the gripping device comprises a shut-off valve or a restrictive device which may or may not be adjustable, which shuts off or constricts the connection between the apparatus and the vacuum chamber when the apparatus is blowing air. Because of this, the gripping magnet can be moved away from the gripped object more easily.  
         [0009]     In an embodiment the means of releasing comprises a cylinder, the interior of which is the pressure chamber, as well as a piston that can move in the cylinder, to which piston a magnet is fastened, and where the air inlet is situated nearby the open side of the vacuum chamber in the cylinder.  
         [0010]     In another embodiment the means of releasing comprises an inflatable bellows, the interior of which is the pressure chamber, which bellows is situated round about the gripping magnet or is connected to the gripping magnet and when it is inflated pushes the object and the gripping magnet away from each other. In this embodiment, the sealing edge is preferably situated on the bellows&#39; underside.  
         [0011]     It is noted that a gripping device with a vacuum gripper and a gripping magnet and an inflatable bellows for pushing the gripping magnet and the gripped object away from each other can be used independently of a pump which works in two directions and that the possibility expressly be kept open to protect the embodiments of the gripping device with a bellows which are independent of the use of a pump that works in two directions.  
         [0012]     In still another embodiment, the means of releasing comprises a membrane to which the gripping magnet is connected, which membrane is a wall of the pressure chamber and can move the gripping magnet.  
         [0013]     The invention also relates to a lifting device for lifting an object, in particular a plate, comprising a gripping device according to the invention, as well as a means of lifting in order to raise and lower the gripping device.  
         [0014]     Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0015]     The accompanying drawings illustrate the present invention. In such drawings:  
         [0016]      FIGS. 1 and 2  show a first embodiment of the gripping device according to the invention with a gripping magnet which can move in a cylinder, while it is gripping and releasing a plate respectively;  
         [0017]      FIGS. 3 and 4  show a second embodiment of the gripping device according to the invention with a gripping magnet attached to a piston that can move in a cylinder, while it is gripping and releasing a plate respectively;  
         [0018]      FIGS. 5 and 6  show a third embodiment of the gripping device according to the invention with a gripping magnet which can move by means of a membrane, while it is gripping and releasing a plate respectively;  
         [0019]      FIGS. 7 and 8  show a fourth embodiment of the gripping device according to the invention with a bellows round about a gripping magnet which can move, while it is gripping and releasing a plate respectively; and  
         [0020]      FIGS. 9 and 10  show a fifth embodiment of the gripping device according to the invention with a bellows situated round about a gripping magnet, while it is gripping and releasing a plate respectively. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     The above-described drawing figures illustrate the invention, a gripping device  1  for gripping and lifting an object  2 , such as a plate.  
         [0022]     In  FIGS. 1 and 2 , a first embodiment of the gripping device  1  includes a means of gripping according to the invention is shown while it is gripping and releasing the plate  2  respectively. While the plate  2  is described herein, those skilled in the art will recognize that alternative objects may also be gripped with the present invention, as such alternatives should be considered within the scope of the present invention.  
         [0023]     In this embodiment, the means of gripping is made up of a vacuum gripper  3  and a gripping magnet  5 , which are integrated into one unit. The unit has a casing  6  in which the gripping magnet  5 , which is a permanent magnet, is situated. The vacuum gripper  3  has a vacuum chamber  7  which is open on the underside  11  and is bounded along its perimeter by a flexible saucer-shaped wall  9 . The underside of the wall  9  is provided with a sealing edge  13 . One wall of the vacuum chamber  7  is provided with a vacuum inlet  12  which is connected to a means of producing a vacuum through a passage  15 , situated in the casing  6 .  
         [0024]     In this embodiment the means of releasing is a means of retracting in order to retract the gripping magnet  5 . The means of retracting comprises a piston  17  attached to or otherwise associated with the gripping magnet  5  and adapted to move in a cylinder  18 . The space in the cylinder  18  is a pressure chamber  19  that through an air inlet  21  situated near the open side  11  of the vacuum chamber in the casing  6  is connected to the passage  15  and is connected to a means of blowing air. The means of producing a vacuum and the means of blowing in air are integrated in a pump which works in two directions (not shown). An additional passage  23  serves as a vent for the pressure chamber above the piston  17 .  
         [0025]     There is an adjustable restrictive device  25  (shown schematically) in the vacuum inlet  12 . The pump that works in two directions can create a vacuum in the vacuum chamber  7  and can suck the piston  17  downwards (see  FIG. 1 ) or blow the piston  17  upwards (see  FIG. 2 ).  
         [0026]     In order to grip the plate  2 , the gripping magnet  5  is brought into the lower position, see  FIG. 1 , by drawing air out of the pressure chamber  19  under the piston  17  through the passage  15 . In this position, the gripping magnet  5  is close to the plate  2  and the plate  2  is pulled up towards it. When in the process of gripping, a vacuum is created in the space  7  as a result of which the plate  2  is also gripped by the vacuum gripper  3 .  
         [0027]     In order to release the plate  2  the gripping magnet  5  is retracted, see  FIG. 2 . This takes places by blowing air into the pressure chamber  19  under the piston  17  through the passage  15 . By doing this, the piston is pushed upwards and comes to a distance from the plate  2 , as a result of which the magnetic attraction is reduced and the force of gravity exerted on the plate  2  overcomes the magnet&#39;s force of attraction. In addition, air is blown into the vacuum chamber  7  at the same time as a result of which the attraction of the plate  2  due to the vacuum is ended and it is blown away from the gripping device  1 .  
         [0028]     In  FIGS. 3 and 4  a second embodiment of the gripping device  31  according to the invention is shown, again while it is gripping and releasing a plate  32  respectively. Here as well, the means of gripping is made up of a vacuum gripper  33  and a gripping magnet  35 , which are integrated into one unit. The unit has a casing  36  in which the gripping magnet  35  is situated. The vacuum gripper  33  has a vacuum chamber  37  that is bounded along its perimeter on the open side  41  by a wall  39 , which is provided with a sealing edge  43  on its underside. The vacuum chamber  37  is connected through a vacuum inlet  42  and passages  45 ,  47  and  49  to a pump that works in two directions (not shown), which functions as a means of producing a vacuum in one direction and a means of blowing air in the other direction.  
         [0029]     In this embodiment as well, the means of releasing is made up of a means of retracting with a piston  51  which can move in a cylinder  52  and is connected to the gripping magnet  35 . However, this cannot now move in the pressure chamber  53  in the cylinder  52 , but is situated outside the cylinder  52 . Furthermore, the air inlet  55  is not situated in the cylinder wall now, but in the piston  51 .  
         [0030]     In order to grip the plate  32 , the gripping magnet  35  is brought into the lower position, see  FIG. 3 , by creating a vacuum under the piston  51  through the passage  56  and the passages  47  and  49 . At the same time, a vacuum is created in the space  37  through the passages  45 ,  47  and  49 . In order to release the plate  32  the gripping magnet  35  is retracted, see  FIG. 4 , by blowing air under the piston  51  through the passages  47 ,  49  and  56 . Here, a shut-off valve made up of a ball  57  shuts off the air supply to the passage  45 . Because of this, the gripping magnet  35  comes to a distance from the plate  32 .  
         [0031]     In  FIGS. 5 and 6  a third embodiment of the gripping device  81  according to the invention is shown, again while it is gripping and releasing a plate  82  respectively. Here as well, the means of gripping is made up of a vacuum gripper  83  and a gripping magnet  85 , which are integrated into one unit. The vacuum gripper  83  also has a vacuum chamber  87  which is connected through a vacuum inlet  89  to a passage  91  that is connected to a pump which works in two directions. Here also the means of releasing is a means of retracting which can move the gripping magnet  85  away from the open side  93  of the vacuum chamber  87  by blowing air through the passage  91  and an air inlet  95  into a pressure chamber  97 .  
         [0032]     This embodiment of the gripping device  81  is comparable to the first embodiment of the gripping device  1  (see  FIGS. 1 and 2 ), only now the gripping magnet  85  is not guided by the piston and the cylinder&#39;s wall, but by a membrane  99  that is a part of the boundary of the pressure chamber  97 .  
         [0033]     In  FIGS. 7 and 8  a fourth embodiment of the gripping device  101  according to the invention is shown, again while it is gripping and releasing a plate  102  respectively. Here as well, the means of gripping is made up of a vacuum gripper  103  and a gripping magnet  105 , which are integrated into one unit. The vacuum gripper  103  once again has a vacuum chamber  107  which is connected through a vacuum inlet  109  to a passage  111  that is connected to a pump which works in two directions. Here also the gripping magnet  101  can move to and from the open side  113  of the vacuum chamber by blowing air through the passage  111  and an air inlet  115  into a pressure chamber  117 .  
         [0034]     Unlike in the above embodiments, the means of releasing is made up of an inflatable bellows  119  which is situated partially round about the gripping magnet  105  and is connected to it. While air is being blown into the bellows  119 , it swells as a result of which it pushes the plate  102  away from the vacuum chamber  107  and at the same time the bellows  119  pushes the gripping magnet, which is attached to the bellow&#39;s upper side, away from the plate  102 , see  FIG. 8 .  
         [0035]     Finally, in  FIGS. 9 and 10  a fifth embodiment of the gripping device  121  according to the invention is shown in a cross-section, again while it is gripping and releasing a plate  122  respectively. Here as well, a vacuum gripper  123  and a gripping magnet  125  are integrated into one unit. The unit has a casing  126  with a space in the middle in which the gripping magnet  125  is fastened. The vacuum gripper  123  has a vacuum chamber  127  which is connected through a vacuum inlet  128  to a passage  129  that is connected to a means of producing a vacuum (not shown).The vacuum chamber  127  is open on the underside and is bounded along its perimeter by an inflatable bellows  131 , which also is the boundary of the open side  133  of the vacuum chamber. This bellows  131  is provided with a sealing edge  135  on its underside, which is in contact with the plate  122  while gripping the plate, see  FIG. 10 . The gripping magnet  125  is situated inside the sealing edge  135  in the vacuum chamber  127 , in which the vacuum chamber, as viewed from a horizontal direction, is situated round about the gripping magnet  125 .  
         [0036]     In order to release the gripping device  125  and the plate  122  from each other, the means of gripping is provided with a means of releasing, which in this embodiment is the inflatable bellows  131 . The space  137  in the bellows is connected to a means of blowing air (not shown) through an air inlet  138  and an additional passage  139  situated in the casing  126 . When the bellows  131  is inflated it pushes the plate  122  away from the gripping magnet  125 . The means of blowing air and the means of producing a vacuum may be executed here as separate pumps.  
         [0037]     Although in the above the invention is explained on the basis of the drawings, it should be noted that the invention is in no way limited to the embodiments shown in the drawings. The invention also extends to all embodiments deviating from the embodiments shown in the is drawings within the context defined by the claims. Thus, the gripping magnet can also be situated concentrically about the vacuum chamber, instead of concentrically in the vacuum chamber as is shown here.  
         [0038]     While the invention has been described with reference to at least one preferred embodiment, it is to be clearly understood by those skilled in the art that the invention is not limited thereto. Rather, the scope of the invention is to be interpreted only in conjunction with the appended claims.