Abstract:
A device for fixing an additional device, such as a scope or laser sighting device, to a firearm free of play and able to accommodate the ever-changing (recoil and spring-back) forces that occur on the engaging mechanism of the fixing device. In addition to a recoil lug contacting a first stop surface of a first groove, a further adjustable stop is provided, engaging a stop surface in a different groove in a direction opposite, along the line fire, to the first stop surface.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns a device for fixing an additional device to a firearm. The invention in particular relates to a tip-up mounting unit for fastening a longitudinally adjustable stop with tight tolerance (free of play) and able to accommodate the ever-changing (recoil and spring-back) forces that occur on the engaging mechanism when shooting with automatic weapons. 
     2. Description of the Related Art 
     Scope mounts are used to assemble targeting devices, e.g., telescopes, on various firearms. Various types of mounts are known, including pivot mounts, claw mounts, fixed mounts, and tip-up mounts. Tip-up mounts are particularly common among the military types of scope mount. Especially popular are so-called Picatinny mounts, which have scope bases executed according to MIL-STD-1913. Therein the weapon is equipped with a Picatinny rail, which has transverse grooves for receiving a recoil lug. For manufacturing-technical reasons, these transverse grooves have relatively large tolerances in width (5.23 mm+0.23 mm). In the mass production of mounts it is thus not possible to precisely fit the recoil lugs to the transverse grooves. If the clamping force of the tip-up mount on the Picatinny rail is not enough, there results, as a consequence of the constantly changing forces when firing automatic weapons, a relative movement between the assembly and Picatinny rail due to the inertia of the mount plus telescopic sight. This leads to unwanted losses of accuracy when shooting, and a wearing-out of the assembly parts in the clamping area. 
     With a one-piece assembly, with only a single recoil lug, no way is yet know to compensate for this play. Two-piece assemblies, consisting of a front and a rear element, each of which being provided with a recoil lug, offer the possibility of engaging the recoil lugs in their respective grooves of the mount in opposing orientations, i.e., forwards and backwards. Therewith the free play can almost, but not completely, be ruled out. The securing of the mounting on the Picatinny rail is accordingly complicated. Moreover, when changing the assembly to a different Picatinny rail, the established precise positioning of the recoil lugs forwardly and rearwardly may no longer exist due to the tolerances of the groove widths. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the invention to develop a device for attaching an additional device to a firearm, which improves the positional stability of the attachment when using the firearm. 
     According to the invention, locking elements are provided in order to compensate for the free play in the direction of firing attributable to manufacturing tolerances, ensuring a longitudinally force-fitting seating between a mounted recoil lug and a corresponding groove in the rail. In the case of attaching the mounting assembly to other mounting rails, the close-tolerance fit (freedom from play) remains guaranteed. 
     The invention is particularly advantageously used when mounting a rifle scope, a laser sighting device, a lighting device or a night vision device onto a firearm, helmet, or other military or hunting equipment. 
     When seating a tip-up mount on a prism rail of a weapon, this is caused to abut foreword in the direction of firing via a recoil lug. In addition to this, a—manually adjustable or automatically adjustable—stop is brought to bear in the direction away from the direction of fire towards the rear. Thereby, the tip-up mount is fixed free from play in the direction of fire. The ever-changing forces occurring in the case of firing automatic weapons, namely in the direction of recoil and the subsequent return, are thus reliably absorbed and a forward or backward walking of the optics assembly can be ruled out. This is achieved in part by a movable and interlockingly acting additional stop, which, in a first embodiment, by means of a manually adjustable inclined sliding stop, is brought to bear in opposition to the direction of firing and therewith compensates for the tolerance-induced play of the recoil lug in its corresponding groove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This particularly advantageous embodiment of the invention will be explained in detail with reference to drawings. 
       In the drawings: 
         FIG. 1  is a perspective view of a telescopic sight mounted by a tip-up mount on a Picatinny rail, 
         FIG. 2  is a sectional view of a telescopic sight mounted by a tip-up mount on a Picatinny rail in front view, 
         FIG. 3  is a sectional view of a base body of a tip-up mount mounted on a Picatinny rail, 
         FIG. 4  shows an enlarged sectional view of the area of the recoil lug and the supplemental stop, 
         FIG. 5  is a perspective view of a base body in view obliquely from below, 
         FIG. 6  is a perspective view of a base body in view obliquely from below, without additional stop and adjustment, 
         FIG. 7  is a perspective view of a two-part tip-up mount, 
         FIG. 8  is a perspective view of a two-part tip-up mount with an additional base body, 
         FIG. 9  is a perspective view of a one-piece tip-up mount with an additional base body, 
         FIG. 10  is a sectional view of a base body of a second embodiment of a tip-up mount mounted on a Picatinny rail, 
         FIG. 11  is a greatly enlarged sectional view of a pin engaged in a groove of the Picatinny rail, 
         FIG. 12  shows a greatly enlarged sectional view of a pin engaged in a groove with minimum dimension of the tolerance of the slot width, 
         FIG. 13  is a greatly enlarged sectional view of a pin engaged in a groove with maximum dimension of tolerance to the groove width, 
         FIG. 14  is a pin in a spatial representation, and 
         FIG. 15  is a sectional view showing a base body with pins and threaded pin for limiting the displacement path. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The so-called Picatinny rail ( 10 ) according to MIL-STD-1913 th  has developed great popularity, especially in the military sphere, as an interface for attachment of targeting devices and accessories of all kinds. The Picatinny rail ( 10 ) consists of a rail ( 2 ) mounted in the direction of fire on the weapon and is provided on its upper side with a prism ( 6 ) extending in the direction of fire, which is used as an interface for receiving the targeting or auxiliary equipment (see  FIG. 1  and  FIG. 2 ). Introduced in this prism ( 6 ) are grooves ( 7 ) transverse to the direction of fire, which are, according to MIL-STD-1913, arranged at regular intervals of 10 mm. 
     The tip-up mount ( 14 ) shown as an example in  FIG. 1  consists of a base body ( 1 ), on which the receiving elements ( 8 ) are mounted, which receiving elements serve for fastening the telescopic sight ( 9 ). Receiving elements ( 8 ) and base body ( 1 ) can also be manufactured as one piece. In another possible embodiment of the invention, the base body ( 1 ) is made in two parts. The base body ( 1 ) of the tip-up mount ( 14 ) has, on its side facing the Picatinny rail ( 10 ), a fixed extension ( 11 ), which positively engages around a side of the prism ( 6 ) of the Picatinny rail ( 10 ) and thus align the base body ( 1 ) in the direction of fire. In addition, the base body ( 1 ) has a movable clamping element ( 12 ), which is pressed by the clamping lever ( 13 ) to the prism ( 6 ). The pressing can also be brought about using nuts or screws, wing nuts or thumb screws. 
     In order to fix the base body ( 1 ) in the direction of fire, a recoil lug ( 3 ) is provided on the underside of the base body, engaging into one of the grooves ( 7 ) and brought to rest towards the front in the direction of fire before closing the clamping levers ( 13 ) (see  FIG. 3 ,  FIG. 4  and  FIG. 5 ). To compensate for the large amount of free play occurring between groove ( 7 ) and recoil lug ( 3 ) due to the manufacturing tolerances, an additional stop ( 4 ) is brought into contact in one of the grooves ( 7 ), in the direction opposite to the direction of fire, by means of the adjusting element ( 5 ) (see  FIG. 4  and  FIG. 5 ). The base body ( 1 ) has in its&#39; Picatinny rail ( 10 ) facing side a prismatic recess ( 15 ), in which the additional stop ( 4 ) is displaceably guided (see  FIG. 5  and  FIG. 6 ). The orientation of the recess ( 15 ) is at an angle β greater than 0° and less than 90° to the direction of fire and the displacement plane or level of the additional stop ( 4 ) lies parallel to the underside of the base body ( 1 ) (see  FIG. 6 ). 
     In a particularly advantageous embodiment of the invention, the adjusting element ( 5 ) is designed as a screw, whose head ( 18 ) for manual control is provided with a knurl (see  FIG. 5 ). Its shaft ( 16 ) extends through a wall ( 21 ) of the base body ( 1 ) and is secured against displacement along the recess ( 15 ) using at least one securing element ( 17 ), preferably a shaft securing ring. 
     In another possible embodiment of the invention, the movable clamping element ( 12 ) serves as adjusting element whose movement, during the closing of the clamping lever ( 13 ), can be used for displacing the additional stop ( 4 ). The additional stop ( 4 ) is equipped with a stop element ( 19 ). 
     In a particularly advantageous embodiment of the invention, this stop element ( 19 ) is designed as a cutting or clamping sleeve (see  FIG. 5 ). The base body ( 1 ) comprises a recess ( 20 ), into which the stop element ( 19 ) engages (see  FIG. 6 ). 
     The two end positions of the additional stop ( 4 ) along its displacement path are thus defined and must meet the following conditions: 
     1) If the additional stop ( 4 ) is brought by the adjustment element ( 5 ) in one of the grooves ( 7 ) to rest against the direction of fire, the end position in this direction must be not yet be reached. 
     2) If the additional stop ( 4 ) is released via the adjustment element ( 5 ), its end position in this direction must be reached before reaching the stop in the direction of fire. 
     The tip-up mount can thus be removed without interference when it reaches the end position. 
       FIG. 7  shows an example of a possible embodiment of the invention with a two-part base ( 1 ). Therein only one of the two parts has, on its&#39; Picatinny rail ( 10 ) facing side, a prismatic recess ( 15 ), in which the additional stop ( 4 ) is displaceably guided. 
       FIG. 8  shows an example of a possible embodiment of the invention with a two-part base ( 1 ). An additional base body ( 22 ) has, on its&#39; side facing the Picatinny rail ( 10 ), a prismatic recess, in which the additional stop ( 4 ) is displaceably guided. The additional base body ( 22 ) may or may not, however, be mechanically connected with the base body ( 1 ). Through the contact of the additional stop ( 4 ), the additional base body ( 22 ) is pressed against the base body ( 1 ). 
       FIG. 9  shows an example of a possible embodiment of the invention with one-piece base body ( 1 ) and also additional base body ( 22 ), whose execution corresponds with  FIG. 7 . 
     In a further embodiment of the invention, a spring-loaded pin serves as an additional stop, which pushes at an angle of between 0° and 90° against the wall of a groove in the Picatinny rail and thus compensates for the play between the recoil lug and groove. 
     This embodiment is explained in detail with reference to drawings. 
     In the drawings  FIG. 10  is a sectional view of a base body of a tip-up mount mounted on a Picatinny rail,  FIG. 11  is a greatly enlarged sectional view of a pin engaged in a groove of the Picatinny rail,  FIG. 12  shows a greatly enlarged sectional view of a pin engaged in a groove with minimum dimension of the tolerance of the slot width,  FIG. 13  is a greatly enlarged sectional view of a pin engaged in a groove with maximum dimension of tolerance to the groove width,  FIG. 14  is a pin in a spatial representation, and  FIG. 15  is a sectional view showing a base body with pins and threaded pin for limiting the displacement path. 
     The structure of the second embodiment of the tip-up mount ( 51 ) corresponds substantially to the tip-up mount ( 14 ) of the previous embodiment. Here a cylindrical pin ( 52 ) serves substantially as an additional stop, which is urged by the compression spring ( 53 ) against the wall ( 50 ) of one of the grooves ( 7 ) when seated on the Picatinny rail ( 10 ) and thus bring the recoil lug ( 3 ) into engagement forward in the direction of fire (see  FIG. 10 ). 
     In a further embodiment, the pin ( 52 ) may have any other shape, for example substantially rectangular. Also, several springs can also be used. Also, instead of the compression spring, a leaf spring can be used. 
     The displacement of the pin ( 52 ) runs at an angle μ greater than 0° and less than 90°, preferably 15°. The contact surface ( 55 ) of the pin ( 52 ) compensates for this angle again. Thus, the contact surface ( 55 ) lies flat against the wall ( 50 ). To protect the edges of the groove ( 7 ), the pin ( 52 ) is provided with a radius ( 56 ) (see  FIG. 11 ). 
     In another possible embodiment, the contact surface ( 55 ) forms an α to the wall ( 50 ) (see  FIG. 13 ). Thereby the pin ( 52 ) lies with its radius ( 56 ) against the wall ( 50 ). If the displacement path of the pin ( 52 ) were to extend vertically and if this were to exhibit an inclined bearing surface compared to the abutment surface ( 55 ), then the contact would essentially be a line against the groove ( 7 ). This would inevitably lead to compressive deformation, leading to damage to the rail. 
       FIGS. 12 and 13  show the arrangement of the contact surface ( 55 ) of the pin ( 52 ) against the wall ( 50 ) in the case of the smallest or the largest dimension of the tolerance of the width of the groove ( 7 ). The displacement path of the pin ( 52 ) in both directions is limited in such a manner that the pin ( 52 ) upon contact of the contact surface ( 55 ) against the wall ( 50 ) in the case of the minimum dimension of the tolerance of the groove ( 7 ) still has travel room to the base of the bore ( 57 ) (see  FIG. 12 ). At maximum dimension of the tolerance of the groove ( 7 ), the pin ( 52 ) with contact surface ( 55 ) on the wall ( 50 ) has not been reached it&#39;s maximum travel (see  FIG. 13 ). 
     The limitation of the travel of the displacement path of the pin ( 52 ) in the working direction of the compression spring ( 53 ) is brought about by a threaded pin ( 58 ), which engages in the slot ( 59 ) in the pin ( 52 ) (see  FIGS. 14 and 15 ). The threaded pin ( 58 ) can also be designed as a clamping sleeve, straight pin, or any other suitable component. 
     In a further, not illustrated, embodiment of the invention, a manually actuated eccentric shaft serves as an additional stop, which is guided in the base body of the tip-up mount and is operated by a lever element or by means of a tool and is engaged vertically or horizontally in one of the grooves of the Picatinny rail. By rotating the eccentric shaft, this comes to press against one of the walls of the Picatinny rail and thus brings the recoil lug to bear. 
     LIST OF REFERENCE NUMERALS 
       1 . Body 
       2 . Rail 
       3 . Recoil lug 
       4 . Additional stop 
       5 . Adjusting element 
       6 . Prism 
       7 . Groove 
       8 . Receiving member 
       9 . Scope 
       10 . Picatinny rail 
       11 . Fixed extension 
       12 . Movable clamping element 
       13 . Clamping lever 
       14 . Tip-up mount 
       15 . Prismatic recess 
       16 . Shank 
       17 . Securing element 
       18 . Head 
       19 . Stop element 
       20 . Recess 
       21 . Wall 
       22 . Additional base 
       50 . Wall of the groove 
       51 . Second embodiment of the tip-up mount 
       52 . Pin 
       53 . Compression spring 
       54 . Second embodiment of the body 
       55 . Contact surface 
       56 . Radius 
       57 . Bore 
       58 . Screw 
       59 . Slot