Device for blocking a piece on a support plane like a table for operating machines

Abstract: The device comprises: a central pin (18) provided with means (23, 34) for its blocking to the support plane (10) with the axis A of the pin (18) perpendicular to the plane itself; an anular hub (20), freely rotating around the pin (18), provided with driving means (60) for its rotation and having a peripherical male screw cutting eccentric in relation to the axis of the pin (18); and a ring nut (22) having an internal screw cutting (52) coupled to the external screw cutting of the hub (20) and presenting on into periphery at least a face (54, 56) for laterally engaging the piece (W), like a thightening jaw, the coupled screw cuttings of the hub (20) and of the ring nut (22) having an irreversible pitch.

Description: The present invention refers to a device for blocking a piece on a support plane, like a table for an operating machine or for similar applications, cf. e.g. EP-A-0 236 537. The object of the present invention is the realization of a device of this type having a simple and solid structure and of general employment, such as to permit, in cooperation with similar devices, the secure blocking of pieces having the most varied, even irregular, shapes. According to the invention, this object is obtained by means of a device of the considered type, characterized by the fact that it comprises: a central pin provided with means for its secure blocking to the support plane with the axis of the pin perpendicular to the plane itself; an anular hub, freely rotating around the pin, provided with driving means for its rotation and having a peripherical male screw cutting eccentric in relation to the axis of the pin; and a ring nut having an internal screw cutting, coupled to the external screw cutting of the hub and presenting on its periphery at least a face for laterally engaging the piece, like a thightening jaw, the coupled screw cuttings of the hub and of the ring nut having an irreversible pitch. The characteristics and advantages of the present invention will become more apparent from the following description of the preferred embodiment of the invention described in connection with the accompanying drawings in which: Figure 1 is a perspective view illustrating a table for operating machine on which a piece to be worked is fixed by blocking means according to the invention; Figure 2 is a perspective, in large scale view, of a position of figure 1, in which one of the blocking devices and one corresponding control key, of the same devices are illustrated, Figure 3 ia a view in exploded perspective of the blocking device and of its protective cap, Figure 4 is a plan view of the blocking device, and Figure 5 is a diametral sectional view in association with the table and the piece, partially represented. With reference to figure 1, a table for an operating machine, indicated in the whole with 10, presents the ordinary T-shaped fixing grooves, indicated with 12. Checking means, fixed to the table 10, are designed with 14. A piece to be worked is indicated with W, and is fixed to the table 10 by means of three similar fixing devices, according to the invention, all designed with 16. The piece W has been conventionally represesented in the form of a prismatic block; but it might have any other shape, even an irregular one. Referring to the figures 2 to 5, a fixing device 16 comprises a central steel hub 20, free to rotate around the pin 18, and a stell ring nut 22. A T-shaped steel key 24 is joned to the pin 18, as illustrated in the figures 2 to 5, and is inserted in one of the grooves 12. The pin 18 presents at least a longitudinal passing bore and, preferably, as rapresented, a couple of these bores, designed with 26 and disposed at a diameter at the same distance from the axis of the pin 18. Each bore 26 comprises (figure 5) a blinded portion 28 and a smooth portion 30. In its turn, the key 24 presents a couple of threaded bores 32. The fixing of the pin 18 to the table 10 occurs by means of a couple of screws 34 of the internal hexagon type. The heads of these screws remain encased in the blinded portions 28, their stems go through the smooth portions of the passing bores 26 and their threaded portions couple with the threaded bores 32 of the key 12. The pin 18 comprises a cylindrical section of greater diameter 36 and a cylindrical following section of smaller diameter 38, so that it forms a ring-like seat 40 which, by the use, is turned toward the table 10. In a correspondent way, the hub 20 presents a central bore 42 having cylindrical following portions of greater diameter 44 and smaller diameter 46 respectively. As it is possible to observe in figure 5, the portions of greater and smaller diameter of the hub 20 are coupled with the corresponding portions of the pin 18, such as to permit the hub 20 to rotate freely, but precisely, around the axis of the pin 18. Between the two portions 44 and 46 of the bore 42 a ring-like seat is defined, which cooperates with the seat 40 for confining the hub 20 and preventing its removal from the table 10, when the pin 18 is fixed to the same table. It is to be observed that the confinig of the hub 20 is not studied for pressing the hub against the table 10 when the screws 34 are tightened. The annular hub 20 presents a peripherical male screw cutting 50. This screw cutting 50 is eccentric to the common rotation axis of the bore 42 and of the pin 18 for the purpose afterwards explained. In the figures 4 and 5, this rotation axis is indicated with A and the axis of the screw cutting 50 is indicated with E. The ring nut 22 which encircles the hub 20 is provided with an internal screw cutting 52 coupled with the screw cutting of the hub 20. The same ring nut 22 presents on its periphery at least a face to laterally engage the piece W and to thighten it, blocking it, in cooperation with the other blocking means, like a thightening jaw. The pitch of the coupled screw cuttings 50 and 52 is irreversible. The ring nut 22 presents on its periphery at least a face 54 or 56 for laterally engaging the piece W, like a thightening jaw. Preferably, as represented, the ring nut 22 presents a plurality of flat engaging faces 54, 56, placed on its periphery. Also prefarably these engaging faces 54, 56 are flat, tangential ones, placed on the periphery of the ring nut 22 at 90° one from the other. Again preferably, two engaging, diametrically opposed faces 54 are knurled, as it is illustrated in the figures 3 and 5, while the other two faces 56 are smooth. The reason for which certain flat faces, as 54, are knurled and other faces, as 56, are smooth, will be explained afterwards. For blocking a piece like W (figures 1, 2 and 5), it is necessary to carry one of the faces 54 or 56 against the same piece, in cooperation with other similar blocking devices 16. This is consented because of the eccentricity of the hub 20 in relation to the ring nut 22. When each blocking device 16 has been fixed regarding the relative grooves 12 (figure 1) in a position in which the periphery of the ring nut 22 is a few millimeters far from the piece W, one of the faces 54 or 56 is grossly positioned opposite the piece W and then ring nut 20 is rotated around the pin 18. Prefarably, for causing the rotation of the ring nut 20, this is provided with rotating driving means which comprise diametral slots 60, which, in the case represented in figures 2 to 5, are cross like disposed. These diametral slots 60 are made out beginning from an extremity face of the hub 20, far from the table 10. The device 16, according to the invention, is provided with a key 62 (figure 2) which comprises for example a bush 64 provided with teeth 66 engaging the slots 60. The bush 64 presents diametral opposite slots 68 in which a sliding, slippable control rod may be inserted. Alternately, the bush 64 might be provided with a lateral lever having the same function of the rod 70. By means of the key 64, it is possible to cause the hub 20 to rotate clockwise or counterclockwise as indicated by the double arrow C in figure 4. As it is clearly apparent, by means of the rotation of the hub C, it is possible to obtain, due to the eccentricity of the screw cutting 50 of the hub 20, an eccentric movement of the ring nut 22 as indicated by the double arrow D in figures 4 and 5. After having suitably oriented the ring nut 22, it is possible to bring one of the faces 54 or 56 in tight and blocking engagement with a corresponding surface or face of the piece W. The blocking engagement of one of thefaces 54 or 56 with the piece W is mantained stable by means of the friction due to the irreversibility of the two screw cuttings 50 of the hub 20 and 52 of the ring nut 22. As it is possible to observe particularly in figures 2, 3 and 5, the two opposite knurled faces 54 of the ring nut 22 present preferably a knurl formed by a set of riflings tangentially oriented in relation to the axis of the ring nut 22. Moreover, again preferably, these riflings have a saw teeth shaped contour with flat sides turned, in the use, towards the table or support plane 10. This saw teeth shaped configuration, so oriented (figure 5), constitutes a guarantee against the detaching of the piece W from the table 10. The other two flat and smooth faces 56 are utilized for engaging a piece, like W, of tender material for avoiding to damage the surface. By the use, each blocking device 16 may be advantageously covered by a cap 62, for example of plastic material (figure 3) for protecting it from the dust, the chips, the cut oils and so on.

Claims: Device for blocking a piece (W) on a support plane, like a table (10) of operating machine or for similar applications, characterized by the fact that comprises: a central pin (18) provided with means (24, 34) for its secure blocking to the support plane (10) with the axis (A) of the pin (18) perpendicular to the plane itself; an anular hub (20), freely rotating around the pin (18), provided with driving means (60) for its rotation and having a peripherical male screw cutting (50) eccentric in relation to the axis of the pin (18); and a ring nut (22) having an internal screw cutting (52), coupled to the external screw cutting (50) of the hub (20) and presenting on its periphery at least a face (54, 56) for laterally engaging the piece (W), like a thightening jaw, the coupled screw cuttings (50, 52) of the hub (20) and of the ring nut (22) having an irreversible pitch. Blocking device according to the claim 1, characterized by the fact that the pin (18) presents at least a longitudinal passing bore (26) and the filing means of the pin (18) to the support plane (10) comprise a T-shaped key (24), engaging a T-shaped groove (12) of the support plane and presenting at least a threaded bore (32) corresponding to the passing bore (26) of the pin (18), as well as a screw (34) inserted through the passing bore (26) of the pin (18) and screwed into the threaded bore (32) of the key (24). Blocking device according to the claims 1 or 2 , characterized by the fact that the pin (18) comprises a cylindrical section of greater diameter (36) and a cylindrical following section of smaller diameter (38), such as to form a ring-like support seat (40) which, by the use, is turned toward the table (10) and, in a corresponding way, the hub (20) presents a central bore (42) having cylindrical following portions (44, 46) of diameters respectively greater and smaller corresponding to the portions (36, 38) of the pan (18) and such as to define a ring-like support seat (48) cooperating with the support seat (40) for preventing the removal of the hub (20) from the table (10) when the pin (18) is fixed to the same table. Blocking device according to any one of the preceding claims, characterized by the fact that the driving means for the rotation of the hub (20) comprise diametral slots (60) made in its extreme surface, which, in the use, is far from the table (10) and engageable by corresponding teeth (66) or similar projections of a suitable key (62). Blocking device according to any one of the preceding claims, characterized by the fact that the ring nut (22) presents a set of flat engaging faces (54, 56) placed on its periphery. Blocking device of claim 5, characterized by the fact the ring nut (22) presents four flat tangential faces (54, 56) placed at 90° on its periphery. Blocking device according to the claims 5 or 6 characterized by the fact that at least some of the engaging flat faces (54) are knurled. Device according to claim 7, characterized by the fact that the knurl of each knurled face (54) is formed by a set of riflings tangentially oriented in relation to the axis of the ring nut (22). Blocking device according to claim 8, characterized by the fact that the riflings of the knurled face (54) have a saw teeth shaped contour with flat sides turned, in the use, towards the table (10).

Inventors: LAMBERTINI GUISEPPE, LAMBERTINI, GUISEPPE
Applicants: MEC LOMBARDA S R L OFF, OFFICINA MECCANICA LOMBARDA S.R.L.
Application year: 1995
Main classification: B25B5
IPC codes: B25B5