Abstract:
The invention concerns an angular pneumatic gripper structure having a body ( 11 ) formed of two symmetric and identical elements or shells ( 15 ) realised and finished individually using a forming process and then associated and attached face to face to form together a housing chamber of an alternating piston ( 12 ) and means for receiving and guiding an intermediate drive ( 13 ) transversely and some grips ( 14 ) so as to turn driven by the piston through the drive. The elements or shells forming the body are made using die-casting, sintering or forging processes with material suitable for these forming techniques.

Description:
FIELD OF INVENTION  
       [0001]     This invention concerns in general pneumatic grippers for gripping items being machined and/or automatic handling, and refers in particular to improved components for making ready angular pneumatic grippers, that is to say with two jaw holding grips capable of angular movements in opposite closing and opening directions.  
       STATE OF THE ART  
       [0002]     The pneumatic grippers taken into consideration can be different in shape, dimensions and capacity, but each one usually includes a body, a pneumatic piston moving backwards and forwards in a chamber or sleeve in said body, two grips supported and powered in the body, coupled to the piston through a drive, and two jaws fixed to the grip to block an release the item to be handled. The grip are mobile angularly in opposite directions between the opening and closing positions by means of the drive and in response to the alternative movements of the piston. Their rotation can be chosen or adjusted so that, starting from the closed position, each can reach an opening position of about 90°.  
         [0003]     The components of said pneumatic grippers are machine-made on machine tools. Usually their body is a single block and it is formed starting from an initial raw block which is opportunely machined and drilled to make it suitable to receive the operating components and accessories of the chuck.  
         [0004]     A similar construction process of said chucks is however extremely laborious and costly due to the machining operations and the work times required and often because of the minimum machining tolerances needed.  
         [0005]     On the other hand forming techniques, such as die casting, sintering, forging and similar systems are known which enable the construction of items, even finished, with complex shapes and with minimum tolerances and with a high level of precision, both dimensional and surfacial. However, these forming techniques have not been applied to the realisation of the angular pneumatic chucks in question because of the usual configuration of their components.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0006]     An objects of this invention is to adopt advantageously some of the forming techniques mentioned above in the realisation of pneumatic angular grippers so as to eliminate or at least to minimize times and costs of construction and assembly of said chucks.  
         [0007]     Another object of the invention is the realisation of an angular pneumatic gripper composed of a limited number of pre-shaped components, capable of joining complementarily with each other and with interposed auxiliary elements, ensuring the functionality of the resulting gripper, better still increasing the performance and life of the same.  
         [0008]     In order to achieve the above objects of the invention, the body of the gripper is made up of two complementary parts manufactured individually using one of the abovementioned techniques and then assembled to form a solid block ready to receive, support and guide other structural and functional components of the gripper which can also be made using the same forming techniques. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]     The gripper of the invention will however be described more in detail in the description that follows made with reference to the attached drawings, which are indicative and not limiting, in which:  
         [0010]      FIG. 1  shows an exploded view in perspective of the components for the realisation of an angular pneumatic gripper according to the invention;  
         [0011]      FIG. 2  shows an enlarged view in perspective of one of the two shells for the formation of the gripper body, the other shell being identical;  
         [0012]      FIG. 3  shows a view in perspective of the assembled grips with the relative support, control and protection elements;  
         [0013]      FIG. 4  shows the group in  FIG. 3  associated with a drive piston;  
         [0014]      FIG. 5  shows an intermediate assembly phase of the gripper;  
         [0015]      FIGS. 6 and 7  show, respectively, an assembled gripper with the grips in the closed and open position.  
         [0016]      FIG. 8  shows a cross section of the assembled chuck with the grips in the closed position; and  
         [0017]      FIGS. 9 and 10  show, respectively, a longitudinal section, a cross section and an end view of the assembled gripper. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     The angular pneumatic gripper shown comprises a body  11 , a piston  12  moving in said body, a drive  13  associated with the piston  12 , two grips  14 , turning in opposite directions, each on its own pin or axis  14 ′, moved by the piston  12  through of the drive  13 , and two gripper jaws, not shown, attached to the ears.  
         [0019]     The body  11  is made up of two symmetric elements or shells  15  which are identical and therefore made using the same mould, advantageously using die-casting, sintering or forging forming processes using any appropriate raw material.  
         [0020]     The two shells  15  are positioned one facing the other. They are matched and then attached to each other as will be described below. Each of them— FIG. 2 —has a support base  16  from which an intermediate section  17  rises overlooked by two shoulders  18  connected by a top crosspiece  18 ′.  
         [0021]     Two ears  19  protrude from opposite sides if the support base  16 , each one having a semi-hole  20 , perpendicular to the base, opening towards the facing shell  15  and having an internal semi-hexagonal recess  20 ′.  
         [0022]     The intermediate section  17  of each shell  15  centrally forms a cylindrical cavity  21  the axis of which is parallel to the support base  16 . Said cavity  21  is open towards the homologous cavity of the facing shell, whereas the opposite part is closed by an end wall  22  in which a hole  22 ′ is drilled. Laterally, the intermediate portion  17  has two sides  17 ′ each of which has a longitudinal groove  17 ″ parallel to the axis of said cylindrical cavity  21 .  
         [0023]     In the intermediate section  17 , on the opposite parts of the cylindrical cavity  21  and parallel to it, holes  23  are drilled symmetrically, for example two on each side. From the open side of the cavity  21 , in line with the two holes  23  mentioned, and diagonally opposite, centring lugs  23 ′ have been shaped, whereas in line with the other two holes  23  there are recesses  23 ″.  
         [0024]     The top shoulders  18  of ach shell  15  form a chamber  24  in the manner of a protective cap  34 , which on one side is open towards the front shell and on the other has an opening  24 ′. In the chamber  24  there is a sliding surface  25  at the bottom and on the sides opposite this, two housings  26 . The sliding surface  25  is placed in parallel above the cylindrical cavity  21  and has at one end, on the open side of said cavity, a half-slot  25 ′. In each lateral housing  26  inside the chamber  26  is housed a support element  27  to support the pins or rotation axis  14 ′ of the ears  14 .  
         [0025]     The piston  12 , the drive  13 , the grips  14  and the supports  27  can also be realised using one of the forming techniques mentioned above.  
         [0026]     The piston  12  is equipped with peripheral seals  12 ′ and dimensioned to be housed and slide in the cylindrical cavities  21  of the two shells when these are joined together to form the body  11 .  
         [0027]     The drive  13  is sledge shaped and has a central hole  28  and on the two opposite sides two indexing rack sections  29 .  
         [0028]     The grips  14  are formed by the same mould. Each of them has a cylindrical bottom section  30  crossed by a polygonal hole  30 ′. Each grip is associated with two gear wheels  31 , one on each side, each one having, on one side, a polygonal hub  32  to house and fit into the transverse polygonal hole  30 ′ of the grip and, on the opposite side, a cylindrical hub  32 ′ to house and turn in a corresponding housing  27 ′ shaped in the abovementioned support element  27 . A bolt  33  passing through the hubs  32 ,  32 ′ of the geared wheels  31  fixed these to the sides of the respective ear  14  and forms the rotation axis  14 ′ of the ear on and with respect to the support element  27 .  
         [0029]     On the side of each geared wheel  31  on the side of the polygonal hub  32 , therefore towards the ear  14 , a neck  31 ′ is shaped to which the protective cap  34  is associated. This cap is shaped to engage at the same time with the neck of the collateral gear wh els of the two grips. Both above the centre and below the ends, it has some ov rhangs  35 ,  36 , respectively, facing towards the cap associated with the facing gear wheels and acting as scrapers for the external surface of the cylindrical section of the grips.  
         [0030]     For equipping one gripper, the geared wheels  31  are fixed to the opposite sides of the two grips  14 , by the interposition of the protective caps  34  between the geared wheels and the grips and making sure that the two collateral geared wheels interlock and their cylindrical hubs  32 ′ are supported on the support elements  27  as shown in  FIG. 3 . Then the drive  13  is linked on one side to the geared wheels  31  and on the other to the piston  12  as shown in  FIG. 4 . The drive  13  is positioned with its indexing rack  29  facing towards the geared wheels  31  on the sides of one of the grips to mesh with them, and is connected to the piston  12  by means of a drive pin  37 — FIGS. 1, 9  and  10 . The subassembly assembled in this way and corresponding to  FIG. 4  is then mounted between the two shells  15  positioned facing each other as shown in  FIG. 5 . To be precise the piston  12  is made to house in the cylindrical cavities  21  which are in line, forming together a chamber for the piston, and the drive pin  37  houses in the slot  25 ′ above said cavities. In this way the drive  13  rests on the sliding surface  25 , the support elements  27  fit into the housings  26  formed by the top shoulders  18  of the shells themselves and the grips  14  reach into the gaps between said shoulders. Finally the two shells  15  are fixed to each other by means of bolts  38  and relative nuts  39  inserted in the holes  23  so as to form a single body encompassing the function elements of the gripper, as shown in  FIGS. 6 and 7 . With the shells assembled, th lateral ears  19  form with their half-holes  20 , housings for the anchoring screws of the gripper on a support when in use. In each of said housings  20 , thanks to the semi-hexagonal recesses  20 ′, a nut  20  can be housed and retained which allows the application of a respective anchoring screw both from the bottom and the top, according to needs.  
         [0031]     In the gripper manufactured in this way, the piston can be simple or double effect moved by a pneumatic fluid delivered/discharged alternatively in the cavity in which the piston is housed. The alternating movements of the piston correspond to similar movements of the drive  13 , whose indexing rack provoke, through the meshed geared wheels, the rotation of the grips in opposite directions between a closed position in which the grips are neared— FIG. 5 , and an open position in which the grips are separated, turned in opposite directions— FIG. 7 . Rotation of the grips can reach up to about 90° and can, however, be adjusted with the use of spacers which limit the stroke of the piston.