Patent Publication Number: US-2015061205-A1

Title: Gripping device

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a gripping device with a housing and at least one jaw that can be moved along a travel direction inside a housing. Objects can be gripped or clamped with such gripping devices. Such gripping devices are known, for example, from DE 197 04 444 C1 or DE 196 04649 C2. A gripping device is known from US 2001/0024045 A1, which provides a pin that protrudes perpendicularly from a piston. 
     The object of this invention is to propose a gripping device of the type described in the introduction, which has a comparatively simple structure, which has sufficiently strong gripping forces and with which objects can be reliably gripped or clamped. 
     SUMMARY OF THE INVENTION 
     This object is achieved with a gripping device having the characteristics of the independent claim. In such a gripping device, the jaw has a piston section that limits a pressure space provided in the housing. Furthermore, the jaw has an end section with a circular cross-section, which reaches through the housing, wherein the end section is disposed eccentrically with respect to the piston section. Consequently, the central longitudinal axis of the end section is disposed parallel and offset from the central longitudinal axis of the piston section. As a result, transverse forces introduced into the end section can be directed via the piston section into the housing, providing protection against rotation. Because the end section has a circular cross-section, it is still possible to provide sufficient sealing between the end section and the housing. 
     It is possible for the piston section to have an outer surface and the end section to have an outer surface, wherein the outer surface of the piston section extends outside of the outer surface of the end section. The outer surface of the end section is then located inside the outer surface of the piston section. 
     Further, it is advantageous if the cross-section of the piston section is circular, oval, or rectangular with rounded edges. Even if the cross-section of the piston section is circular, transverse forces introduced into the end section can be reliably directed into the housing via the piston section. By providing a rectangular cross-section with rounded edges in combination with a housing with a rectangular cross-section, the power density of the gripping device can be increased. 
     In an advantageous embodiment, two jaws are provided, which can be moved along the travel direction toward and away from each other, and each of which has a contact section that extends along the travel direction such that both of the contact sections are suitable for supporting each other. Support can be provided by indirect means, for example, with sliding elements or casters, or by direct means. The contact sections are preferably located in a central longitudinal axis of the piston section and of the end section. When the jaws move, the two jaws, in particular in the region of their contact sections, slide directly against each other. Because they slide directly against each other, the jaws are prevented from rotating around their longitudinal axis or around the longitudinal axis of the end section. Transverse forces acting on an end section are then directed not only into the housing via the eccentricity of the end section and piston section but also into the other jaw via the contact sections. 
     Moreover, it is conceivable to provide a supporting element in the housing, which engages in a guide section on the jaw that extends in the travel direction. In this way, too, transverse forces acting on the end section can be directed into the housing. 
     The supporting element can be disposed transversely with respect to the travel direction of the jaw and extend, at least in sections, through at least the one jaw. If two jaws are provided, the supporting element can extend through both jaws, in particular, in the region of the contact sections of the jaws. Each one of the section elements will then serve to support the anti-rotation protection of the end sections of both jaws. The supporting element can be constituted like a bolt and preferably have a circular cross-section and/or a flattened cross-section. In particular, in the region in which it interacts with the jaws, it can be constituted flattened with two contact surfaces that extend parallel to each other. Because of the enlarged contact surface between the supporting element and the jaws, lower surface pressure can be achieved. 
     The supporting element constituted, in particular, like a bolt can have an adjustment section that interacts with the jaws such that the two jaws are moved synchronously. The adjustment section therefore interacts with both jaws. In particular, it can be constituted to rotate around the longitudinal axis of the bolt-like supporting element. On the one hand, it is conceivable for the adjustment section to be constituted to rotate on the supporting element. On the other hand, it is conceivable for the supporting element together with the adjustment section to rotate around the longitudinal axis of the supporting element. If the supporting element is constituted flattened in the region of the jaws with mutually opposite contact surfaces, rotation of the supporting element around the longitudinal axis is not possible; in that case, the adjustment section must be constituted to rotate around the supporting element. 
     For the purposes of motion coupling of the jaws over the adjustment section, it is advantageous if both sides of the contact sections that face each other have a recess and if the adjustment section is disposed in the region of this recess. The adjustment section can have guidance pins that extend transversely with respect to the travel direction, which interact with guidance grooves on the jaw, which are disposed in the respective recess. Preferably, the configuration is such that whenever the jaws are moved toward or away from each other, the adjustment section is rotated around the longitudinal axis of the supporting element. When the adjustment section rotates, the guidance pins therefore move along a circular segment. The guidance pins preferably extend along a straight line, which extends perpendicular to the supporting element. 
     Further advantages and advantageous embodiments of the invention are to be found in the following description based on which examples of the invention are described and explained in more detail. The figures show: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  a longitudinal section through a gripping device with extended jaws; 
         FIG. 2  the jaws of the gripping device according to  FIG. 1  without housing; 
         FIG. 3  a section according to  FIG. 1  with jaws retracted; 
         FIG. 4  the jaws according to  FIG. 3  without housing; 
         FIG. 5  a jaw shown as a single part; 
         FIG. 6  a side view of the supporting element according to  FIGS. 1 to 4 , 
         FIG. 7  a longitudinal section through a further embodiment of an inventive gripping device, 
         FIG. 8  a further longitudinal section through the gripping device according to  FIG. 8 , and 
         FIG. 9  the supporting element of the gripping device according to  FIG. 7  shown as a single part. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1 to 4  show a gripping device  10  with a housing  12  and two jaws  14 ,  16  in housing  12 , which can be moved toward and away from each other. The jaws  14 ,  16  have a cylindrical (in cross-section circular) end section  18 , each of which reaches through the respective end face  20  of the housing  12 . Ring-like sealing elements  19  are provided around the end sections  18  to prevent media from entering the housing  12 . The respective jaws  14 ,  16  also comprise a piston section  22 , which remains in the housing  12 . The respective piston sections  22  are provided in a cylinder space  24 . Pressure can be applied to each of the two piston sections  22 , wherein the piston section sides  26  that face each other delimit a common pressure space  28 . When pressure is applied to the pressure space  28 , the jaws  14 ,  16  move away from each other along their travel direction  17 . 
     The piston sections  22  each delimit a pressure space  30  on the sides facing away from the pressure space  28 . When pressure is applied to the pressure spaces  30 , for example, by a common pressure tube, and when pressure space  28  is depressurized, the jaws move toward each other. 
     As can be seen in particular in  FIGS. 2 ,  4 , and  5 , the respective end section  18  is disposed eccentrically with respect to the respective piston section  22 , while the central longitudinal axis  32  of the respective end section  18  is disposed offset from the central longitudinal axis  34  of the respective piston section  22 . In this way, when transverse forces Q occur, i.e. forces that produce a torque M around the central longitudinal axis  32  of the end section  18 , rotation of the end section  18  in housing  12  can be prevented. Transverse forces Q occurring at the end section  18  are directed via the respective piston section  22  into the housing  12 . Moreover, the two jaws  14 ,  16  each have a contact section  36  that extends in the travel direction  17 , wherein the contact sections  36  of the two jaws support each other. The contact sections  36  are then in a plane that extends in the longitudinal direction, through the central longitudinal axes  34  and  32 . Further anti-rotation protection of the end sections  18  can be achieved by the mutual support of the jaws  14 ,  16  in the region of the contact sections  36 . 
     As is furthermore apparent from  FIGS. 1 to 4 , a supporting element  38  is provided, which is constituted like a bolt and which extends transversely with respect to the travel direction  17 . The supporting element  38  extends through the piston sections  22  of the jaws and runs perpendicular to the contact sections  36 . The jaws  14 ,  16  provide groove-like guidance sections  40 , in which the supporting element  38  is disposed. Comparatively little play is provided between the section elements  38  and the groove-like guidance sections  40 , so that the interplay between the supporting element  38  and the jaw sections surrounding the groove-like guidance sections  40  support anti-rotation protection of the end sections  18 . 
     To synchronize the movement of the jaws  14 ,  16 , an adjustment section  42  is provided at the supporting element  38 . The adjustment section  42  is rotatably disposed around the central longitudinal axis  44  of the supporting element  38 . 
     Furthermore, as is clear from  FIGS. 1 to 3 , the adjustment section  42  is provided in a recess  46  of the contact sections  36  facing each other. As  FIG. 6  furthermore shows, the adjustment section  42  has guidance pins  48  and  50  at its diametrically opposed end sections, which extend in the direction of the central longitudinal axis  44  of the section element  38 . The guidance pins  48 ,  50  reach into guidance grooves  52  (clearly visible in  FIG. 5  on the jaw side), each of which is located in the region of the recess  46 . 
     Another advantage of the gripping device shown in the figures is that the two jaws  14 ,  16  are constituted identically, which reduces costs in series production. 
     Starting from the extended final position of the jaws  14 ,  16  shown in  FIG. 1 , when pressure is applied to pressure spaces  30  and when pressure space  28  is depressurized, jaws  14 ,  16  or the end sections  18  of jaws  14 ,  16  are moved toward each other. This results in the adjustment section  42  being rotated around axis  44 ; the guidance pins  48 ,  50  therefore move around a circular path. Because the guidance pins  48 ,  50  are disposed captively in the respective guidance grooves  52 , they move, starting from the position shown in  FIG. 1 , initially within the respective guidance grooves  52  away from the central longitudinal axis  34  until they reach a middle position and then back towards the central longitudinal axis  34 , until they reach the end position shown in  FIG. 3 . The totality of these movements can result in synchronization of the movement of the jaws  14 ,  16 . The clamping device represented in the figures consequently has the advantage that comparatively large gripping and clamping forces can be provided when adequate pressure is applied to the pressure spaces  30 ,  28 . Moreover, reliable anti-rotation protection of the jaws  14 ,  16  can be achieved in the basic housing, wherein the jaws are also moved synchronously. 
     The gripping device  100  depicted in  FIG. 7  and essentially corresponds to gripping device  10  according to  FIGS. 1 to 6 , wherein the relevant components are assigned reference numbers. The gripping device  100  differs from the gripping device  10  shown in  FIGS. 1 to 5  by the fact that the bolt-like supporting element  102  is flattened. In particular, in the region in which the supporting element interacts with the jaws, it has two contact surfaces  104  that extend parallel to each other. The distance between the contact surfaces  102  is slightly smaller than the aperture dimension of the guidance sections  40  that take up the supporting element  102 . As a result, a larger supporting surface between the supporting element  102  and the jaws  16 ,  18  is provided, wherein a lower surface pressure between the supporting element  102  and the jaws when traversing the jaws  16 ,  18  can be implemented. 
     As  FIG. 8  clearly shows, the guidance pins  48 ,  50  of gripping device  100  have, in the regions in which they engage with the guidance grooves  52 , a substantially rectangular sliding piece  106  rotatably disposed on the guidance pins  48 ,  50 . The sliding piece  106  has a width that is slightly smaller than the aperture dimension of the guidance grooves  52 . As a result, improved sliding characteristics and, in particular, a lower surface pressure between the guidance pins  48 ,  50  and jaws  16 ,  18  can be provided.