Abstract:
The invention relates to a device for moving and positioning an object in space, having at least three actuator arms each connected to a motor/drive unit and pivotable about a motor/drive axis. The free end of each actuator arm is jointedly connected by connecting rods to a support element having at least one gripping device that can be connected to a vacuum source via a vacuum hose. The gripping device is provided with a suction opening for suctionally gripping the object. According to the invention, the vacuum hose is guided by the support element to the motor/drive axis of one of the motor/drive units, and can be connected to the vacuum source by a rotatable hose joint disposed substantially in the motor/drive axis and rotatable about the motor/drive axis.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a device for moving and positioning an object in space, having at least three actuation arms, each connected to one motor-drive unit and pivotable about a motor/drive axis, wherein, for gripping the object by suction, the free end of the actuation arm is pivotably connected via vacuum rods to a support element having at least one gripping means, connectable to a vacuum source via a vacuum hose. The device for moving and positioning an object in space is a device known in the professional world as a robot with parallel kinematics, also known by the term “delta robot”. 
       PRIOR ART 
       [0002]    In delta robots, the hose guidance from the gripping tool to the vacuum supply is conventionally done via the vacuum rods and via a freely suspended piece of hose about 1500 mm long. This self-supporting hose on the one hand requires stability, so as to be suspended in self-supporting fashion in space, and on the other flexibility, to ensure the extreme motions of the robot. The hose is stressed by both torsion and flexion and can begin to vibrate. If the robot and the hose move in opposite directions, a jerk can occur that not only impairs the precision of the robot but also puts a heavy load on the hose. For that reason, the hose is exposed to high wear and must therefore be replaced after only a short time. 
       SUMMARY OF THE INVENTION 
       [0003]    The object of the invention is to propose a hose guide for a device of the type known at the outset which has less vulnerability to wear than the hose guide, known from the prior art, with the self-supporting hose. 
         [0004]    To attain this object according to the invention, the vacuum hose is guided by the support element toward the motor/drive axis of one of the motor-drive units and is connectable to the vacuum source via a hose joint that is disposed essentially in the motor/drive axis and is rotatable about the motor/drive axis. 
         [0005]    The torsion of the hose is released by a rotatable coupling part. Since a delta robot has only a purely rotational motion in the motor/drive axis of the actuation arms, this coupling part is placed in the axis of rotation of one of the actuation arm drives. Thus the hose has to compensate only for the angular motions between the actuation arm and the vacuum rods and the angular motions of the support element, which now causes only slight bending moments in the hose. Thus the hose can be guided closely on the actuation arm and on the vacuum rods. 
         [0006]    Since the actuation arm moves, the hose is shifted farther in the direction of the motor axis. At the end of the actuation arm, the hose is provided with an angle piece that forms the rotatable part of a “hose joint”. The axis of rotation is located virtually in the motor/drive axis of the actuation arm. 
         [0007]    Preferably, the vacuum hose is guided along the vacuum rods and actuation arms and is detachably fixed by means of fastening elements. 
         [0008]    The fastening element on the actuation arm is preferably mounted in vibration-damping and play-compensating fashion. 
         [0009]    So that the rotatable hose joint can be shifted quickly and without a tool, it is preferably equipped with a fast-action closure, in particular a bulkhead stuffing box or a bayonet mount. 
         [0010]    The hose guide according to the invention, compared to the former version with the self-supporting hose, has the following advantages:
       Fast removal of the hoses for cleaning   The hoses are less stressed because of the release of the torsion, and softer hoses can be used; the service life is extended   Greater safety from better-controlled hose guidance   Greater precision from lesser interfering forces on the robot   Vibration of the hoses is avoided.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Further advantages, characteristics of details of the invention will become apparent from the ensuing description of preferred exemplary embodiments and from the drawings, which schematically show 
           [0017]      FIG. 1 , an oblique view on a delta robot; 
           [0018]      FIG. 2 , an oblique view on a delta robot equipped with elements for the hose guidance according to the invention; 
           [0019]      FIG. 3 , the principle of laying hose in the delta robot of  FIG. 2 ; 
           [0020]      FIGS. 4-6 , oblique views on the hose joint assembly of  FIG. 2 , shown enlarged; 
           [0021]      FIG. 7 , an oblique view on a hose fastening on a connecting arm of  FIG. 2 , shown enlarged. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0022]    A delta robot  10  shown in  FIG. 1  has a base element  12 , with a horizontal mounting plane, and three mounts  14 , protruding from the base element  12 , each for receiving one motor-drive unit  16 . One actuation arm  18 , pivotable about the motor/drive axis s, is seated on each gear shaft, defining a motor/drive axis s, of each motor-drive unit  16 . The three motor-drive axes s are located in a plane parallel to the mounting plane of the base element  12 , and their intersections form the corners of an equilateral triangle. A first joint rod  20 , defining a first joint axis m located parallel to the motor/drive axis s, is affixed to the free end of each actuation arm  18 . Each first joint rod  20 , on each of its two ends, has a first joint part  22  of a respective first ball joint  24 . The paired first joint parts  22  are disposed mirror-symmetrically to one another relative to a respective vertical plane, and the three vertical planes intersect in a common vertical axis, forming an axis of symmetry for the disposition of the three motor-drive units  18 , and form an angle of 120° each from one another. 
         [0023]    A support element  26 , equipped essentially as a plate with side edges  28  forming an equilateral triangle, also called a tool holder or platform, is equipped on each of the three side edges  28  with one second joint rod  30 , defining a second joint axis n. Each second joint rod  30 , on each of its two ends, has a first joint part  32  of a respective second ball joint  34 . The paired first joint parts  32  of each second joint rod  30  are disposed mirror-symmetrically to one another with respect to an angle bisector of the equilateral triangle that characterizes the support element  26 . 
         [0024]    The spacing between the first joint parts  22  on the free end of each actuation arm  18  is identical to the spacing between the first joint parts  32  on the side edges  28  of the support element  26 . 
         [0025]    One side edge  28  of the support element  26  is associated with each actuation arm  18 . Each pair of identically embodied vacuum rods  36 ,  38 , also called parallel bars, have an end piece  39  on each of their ends, each end piece having a second joint part  40 ,  42 . Each second joint part  40 ,  42 , with a first joint part  22 ,  32  on the free end of the actuation arm  18  and on the side edge  28  of the support element  26 , respectively, forms a corresponding first and second ball joint  24 ,  34 , respectively. 
         [0026]    At a short spacing from the first and second ball joints  24 ,  34 , the two vacuum rods  36 ,  38  are connected to one another via a prestressing element  48 , located essentially parallel to the joint axes m, n. 
         [0027]    The first joint parts  22 ,  32  on the free end of the actuation arm  18  and on the side edge  28  of the support element  26 , respectively, are equipped as balls, while the second joint parts  40 ,  42  on the end pieces  39  of the vacuum rods  36 ,  38  are embodied as sockets, of ball-and-socket joints. 
         [0028]    The two vacuum rods  36 ,  38 , which are of equal length, together with the two joint rods  20 ,  30 , also of equal length, form a set of parallel bars  44 , with one ball joint  24 ,  34  at each corner of the parallelogram. The connection of the actuation arms  18  to the support element  26  via one set of parallel bars  44  each prevents the rotation of the support element  26  about axes in all three dimensions in space. The support element  26  can accordingly move only parallel to itself in reaction to a motion of the actuation arms  18 . The controlled pivoting motion of the actuation arms  18  about their motor-drive axes s is accordingly converted into a linear motion of the support element  26 . 
         [0029]    The support element  26  is connected to the base element  12  via a central shaft  46  for transmitting torques that is telescopically adjustable in its length. The central shaft  46  is affixed to the support element  26  via a cardan joint. On its end opposite from the support element  26 , the central shaft  46  is connected to a drive shaft of a servo motor, not shown in the drawing. Via the central shaft  46 , a rotation of the support element  26  in the three-dimensional space can be generated. 
         [0030]    As can be seen from  FIG. 3 , a downward-projecting gripper element  50  is mounted on the support element  26 , with an intake opening  52  for gripping an object by suction. A vacuum hose  54 ,  54   a ,  54   b  connecting the intake opening  52  to a vacuum source, not shown in the drawing, is affixed detachably to the gripper element  50 . The vacuum hose  54 ,  54   a ,  54   b  is guided upward along a vacuum rod  36  and is fixed detachably to the vacuum rod  36  in hose holders  66 . These hose holders  66  can additionally be embodied for receiving pneumatic hoses  55 . 
         [0031]    In a hose guide according to the prior art, the vacuum hose  54 ,  54   a ,  54   b  is connected to the vacuum source, not shown in the drawing, at the upper end of the vacuum rod  36  via a freely suspended piece of hose that is approximately 50 cm long. 
         [0032]    As shown in  FIGS. 2-7 , the vacuum hose  54 ,  54   a ,  54   b , in a hose guide according to the invention, is guided from the upper end of the vacuum rod  36  along the actuation arm  18  toward the motor/drive axis s and changes over into an angle piece  56 . The free end of the angle piece  56  is located in the motor/drive axis s and can be inserted, as a rotatable joint part  57  of a hose joint  60 , into a coupling and bearing part  58  secured detachably to the base element  12  of the robot  10  via a fast-action closure. This stationary coupling and bearing part  58  communicates with a vacuum source, not shown in the drawings, via a further hose part  54   b , which is detachably connectable to the coupling and bearing part  58  via a coupling piece  62 . 
         [0033]    Thus the hose joint  60  comprises the stationary coupling and bearing part  58 , which is secured by a fast-action closure to a mounting plate  59  affixed to the base element  12  of the robot  10 , and the movable angle piece  56  leading to the actuation arm  18 . 
         [0034]    The complete hose joint  60  can be mounted as shown in  FIG. 2  in the direction of the arrow A. The hoses are snapped out and can thus be replaced or cleaned. The same is true for both the vacuum hose  54  and the pneumatic hoses  55 . 
         [0035]    The angle piece  56  is detachably latched into a crank  64  mounted easily movably on the actuation arm  18  via rubber dampers. This crank  64  on the one hand transmits the requisite torque from the actuation arm  18  to the hose joint  60  and the hose  54 ,  54   a , but at the same time can compensate for slight axial tolerances in position and alignment between the axis of rotation of the hose joint and the motor/drive axis s of the actuation arm  18 . Moreover, this crank  64  has a vibration-damping effect. The crank  66  can additionally be embodied for receiving pneumatic hoses  55 . 
         [0036]    The rotatable joint part  57  can be connected to the coupling and bearing part  58  by means of a bulkhead stuffing box  61  or bayonet mount and can be removed in a simple way. For that purpose, the hose  54 ,  54   a , along with the angle piece  56 , is pulled, out of the snap connections, and the hose joint is rotated toward the rear, so that the bulkhead stuffing box  61  releases the joint. 
         [0037]    Moreover, all the hoses can be replaced via click systems. 
         [0038]    The construction is embodied as a “wipe” and “washdown” construction. The construction is developed hydraulically such that there are no mechanical components in the air flow, so that optimal cleaning is ensured. 
         [0039]    Pneumatic hoses  55  can additionally be guided along the vacuum hose  54 —for instance for operating valves. Since these pneumatic hoses have only small diameters and high flexibility, it is unnecessary to disconnect them by means of a rotary joint. Instead, without any drawback, these hoses can be guided onto the actuation arm by means of a sufficiently long self-supporting piece of hose.