Abstract:
Tool with self-locking grip featuring a handle ( 1 ), two levers ( 2   a ) and ( 2   b ), and a self-locking device ( 3 ), in which the handle ( 1 ) features a main body ( 45 ), containing two prismatic housing-guides ( 4   a ) and ( 4   b ) which hold the two levers. These are removable and interchangeable with other levers for performing different mechanical functions, where the self-locking device ( 3 ) is kinetically connected between the main body ( 45 ) and one of the levers. The main body ( 45 ) also contains a third prismatic guide ( 9 ) for a further removable lever ( 10 ); this lever, being connected as required to the same a self-locking device ( 3 ) and sliding inside its own housing, approaching a counter element ( 14 ) fixed to the main body ( 45 ) allows vice-like fastening of the tool to a protruding part of the work bench.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a tool with self-locking grip, interchangeable head-pieces and clamp for fastening to a work bench. 
     DESCRIPTION OF THE RELATED ART 
     It is well known that there is currently a vast range of work tools made up essentially of two levers, also known as gripping arms, which are permanently fastened to the handle, with at least one of the gripping arms or levers being mobile. 
     Jaws are generally provided at the end of the arms, for holding a workpiece. In some cases the ends of the arms comprise devices specially adapted to some operations, for example, for cutting a pipe, punching holes, etc. 
     These work tools are generally designed to perform just one task, depending on the type and shape of the jaws, the means provided for regulating the distance between the ends of the arms, and the possibility of locking the arms using a specific self-locking system. 
     For this reason, there is an almost endless variety of two-gripping arms tools on the market today, the more common of which being: self-locking pliers with screw-adjustment of the distance between the jaws and the locking pressure; adjustable pipe wrenches which allow the distance between the jaws to be set; wrenches featuring one movable jaw which slides along a worm screw-lead screw system; pipe cutters with cutting wheel set at the end of at least one of the gripping arms; punches for punching holes in soft sheet material, etc. 
     As a result, different operations normally require the purchase of different tools with greater expense and transport and handling problems. 
     U.S. Pat. No. 2,312,425 describes a wrench wherein it is easy to place the jaws in gripping relation to the work, and having interchangeable jaws of different contours, suitable to particular types of work. 
     The wrench comprises an elongated flat transversely rectangular casing having an open end and a closed end, and an elongated longitudinal slot in one edge thereof, a pair of jaw members having flat shanks extending into said open end of the casing and relatively slidable in edge-to-edge engaging relation therein, inwardly and outwardly of said open end, respectively, into different positions, detent means for releasably holding one shank in different positions, a spring in said casing having its ends fastened to the inner end of the other shank and to the closed end of the casing, respectively, in the line of movement of said other shank and tensioning said other shank against outward sliding, and means to slide said other shank outwardly in opposition to said spring comprising a lateral edge lug on said other shank extending into the slot in said one edge of the casing flush with said edge, a pair of opposed ears extending from said one edge of the casing at opposite sides of said slot, a cam pivoted between said lugs and having a handle and a radial shoulder rotatable into said slot into camming engagement with said lug. 
     The main disadvantages of the wrench consist in that is difficult to unfasten the spring and to interchange the shank without disassembling the casing. 
     The interchangeability is theoretic more than practical. 
     Moreover, the thickness of the object to be gripped does not allow the handle to find a rest in the casing. 
     Furthermore, the user must hold the wrench in his hand while he is working, and this means that one hand is constantly engaged. 
     Finally, the compression of the handle always causes the lower jaw to move towards the upper jaw, whereas in some works it is more convenient that the upper jaw moves towards the lower one. 
     In U.S. Pat. No. 2,149,541 a wrench is disclosed having a handle and a pair of complemental jaws. The jaws have some type of removable jaw members attached to the regular jaws of the wrench, in order to provide alternatively a smooth flat clamping surface on the jaws, or a punch member, or a cutting pipe device. 
     The main defect consists in that the jaws are not interchangeable, but may just be fitted by applying thereto devices of reduced dimensions, which aren&#39;t practical and are weak. Further disadvantages consist in that the wrench lacks a device for blocking the jaws in position, and that the push of the user on the handle is not balanced, thus forcing the user himself to use not only one, but both hands to do his work. 
     Furthermore, none of the more commonly available tools has the option of being fastened directly to the work bench; indeed, even tools designed to hold two objects for operations such as welding or gluing, must be fastened to the bench using a traditional vice, in order to allow the user to have both hands free. 
     Said bench vice, may also damage or deform the handle of the tool. 
     SUMMARY OF THE INVENTION 
     The aim of this invention is to eliminate all of the problems described above. 
     In particular, the main objective of the invention is to realize a tool with removable and interchangeable gripping arms, for performing a wide variety of tasks. 
     A further objective is the possibility of fastening the tool to the work bench using a specific, incorporated device, which is operated by the same self-locking system of the arms. 
     These and other objectives are fulfilled by the invention, a self-locking tool comprising a handle, two gripping arms and a self-locking system, wherein the handle of the tool comprise a main body with two prismatic housing-guides, holding and guiding said two arms; the arms are removable and interchangeable with other arms and fitted with ends adapted for performing a range of mechanical functions; the self-locking device is connected between the body of the handle and one of the arms, so that operation of the device causes a sliding of said one of the arms, whose end approaches the end of the other gripping arm, this last being fixed inside its housing, to give a gripping effect and locking into position when closed. 
     The main body of the handle contains at least a third prismatic housing-guide, for a further removable gripping arm at the opposite end of the handle; this arm being connected to the same self-locking device and sliding inside its housing, for fastening the tool to a workbench, in cooperation with a fixed element. 
     Moreover, the gripping area of the ends of the arms is advantageously fitted with removable devices which can be easily replaced. 
     The advantages of this invention consist, in general, in the fact that several different applications can be performed using one single handle, costs for the purchasing of a complete kit of tools are reduced, and the user can work alone, without using a vice to clamp the wrench. 
     Further advantages are the possibility to obtain a greater opening of the jaws at the end of the gripping arms; the possibility to have a progressive pressure between the end of the gripping arms using a claw device, fitted in the self-blocking lever (useful, for example, when cutting pipes); the high force allowed by the kinematic movement of the self-locking lever (useful for example, to trim or punch), etc. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Finally, further characteristics and advantages of the invention will be better highlighted by the more detailed description as follows, with the help of drawings showing some preferred embodiments and common applications. The drawings are provided as examples only, and do not represent the complete range of possibilities. 
     FIG. 1 shows a side view with hidden lines dashed, of the self-blocking tool in grip closed position, the principle version of this invention. 
     FIG. 2 shows a side view of the same tool, in open release position. 
     FIG. 3 shows a side view with hidden lines dashed, the self-blocking tool in grip closed position, one possible variation. 
     FIG. 4 shows the same variation of the tool as in FIG. 3, in open release position. 
     FIG. 5 shows a side view with hidden lines dashed, the self-blocking tool in grip position closed, a further possible variation. 
     FIG. 6 shows the same variation of the tool as in FIG. 5, in open release position. 
     FIG. 7 shows a side view of the interchangeable gripping arms of the tool. 
     FIG. 8 shows an exploded perspective view of the jaws at the ends of the interchangeable gripping arms, with an example of the replaceable grip zone. 
     FIGS. 9,  10 ,  11 , and  12  show a side view of the tool respectively and illustratively fitted with jaws for holding objects in place for operations such as welding or gluing, jaws for tightening or loosening bolts, jaws with a pipe cutting device, and jaws with a device for punching holes. 
     FIG. 13 shows an exploded perspective view of the fixed element for the locking jaw of the tool, in the versions illustrated in FIGS. 1,  2 ,  3 , and  4 . 
     FIG. 14 shows a perspective view of the sliding block on which the manoeuvring lever of the self-blocking lever device pivots. 
     FIG. 15 shows a perspective view of the ratchet of the handle, which allows the tool to be fastened to the work bench. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the details shown in the figures, the invention features a handle  1 , two gripping arms  2   a  and  2   b , and a self-locking lever device  3 . 
     The handle of the tool  1  comprises a main body  45 , with two internal prismatic housing-guides  4   a  and  4   b , holding and guiding respectively the two arms  2   a  and  2   b.    
     Each of the arms  2   a  and  2   b  comprises a prismatic portion  5   a ,  5   b  which can be inserted in the two prismatic housing-guides  4   a  and  4   b , and external ends  6   a  and  6   b , which remain external to the main body upon insertion. 
     The gripping arms  2   a  and  2   b  are thus removable and interchangeable with other gripping arms, provided that each of said interchangeable gripping arms comprise a prismatic portion, substantially identical to said prismatic portions  5   a  and  5   b , and is fitted with an external end adapted to the use. For example, external ends of the gripping arms may work as jaws as shown in FIGS. 1 to  10 , or support other tools, as shown in FIGS. 11 and 12. 
     In the case where ends  6   a  and  6   b  work as jaws, their gripping portions  7   a  and  7   b  are fitted with a track guide  46 , which allows their replacement to modify the shape of the gripping zone or to change the grip materials. 
     Both the shape and the materials of the gripping portions may be varied according to the requirements of the application. 
     The materials which may be used include rubber, Teflon, copper, etc., in addition to the standard steel. 
     The prismatic portion  5   a  of arm  2   a  comprises, on one side, selective locking means, which in the embodiments shown are obtained with a rack  8 . 
     Furthermore, the main body  45  of the handle  1  comprises a third prismatic housing-guide  9 , for housing and guiding a third gripping arm  10 . 
     The gripping arm  10  comprises a prismatic portion  11  which can be inserted in the prismatic housing-guide  9 , and an end  12  working as a jaw. 
     The prismatic portion  11  of arm  10  also features, on one side, selective locking means  13 , which in the embodiment shown are saw-tooth shaped, like those of the gripping arm  2   a.    
     A removable element  14 , having a gripping portion  15  adapted to cooperate with the corresponding gripping portion of the jaw  12  for fastening the tool to a workbench, is associated to body  45 , with locking means  48  or  49 . 
     The self locking lever device  3  is connected to the main body  45  and to one of the gripping arms, namely the arm  2   a  or the arm  2   b , so that the operation of the device  3  cause said gripping arm to slide inside its guide  4   a  or  4   b , the external end of said arm thus moving towards the end of the other gripping arm, where this last is fixed, giving a gripping effect. Moreover, the device  3  is adapted to lock said gripping arm into position, when closed. 
     With reference to the embodiment of the tool shown in FIGS. 1 and 2, the self-locking device  3  comprises a manoeuvring lever  16 , a spike  17 , a sliding block  18  and a saddle  19 . 
     The manoeuvring lever  16  is pivoted on the sliding block  18  using a pin  20  and connected to saddle  19  through a cam  21 , as shown in FIG. 1, or otherwise using a rod  44 , as shown in the alternative versions of FIGS. 3 and 4. 
     The spike  17  is pivoted on the manoeuvring lever  16  using a pin  47  and is engaged with a rack  22  on the sliding block  18  by the effect of a spring  23 . 
     The spike  17  and the rack  22  allow multiple locking positions of the manoeuvring lever  16 . 
     A worm screw and nut screw device, made up of a reel  24  pivoted on the sliding block  18  and engaged with a nut screw  25 , housed in the main body  45  of handle  1 , allow small movements of the sliding block  18  along the rail guide  34 , and consequently of the manoeuvring lever  16 , for adjusting the gripping force between the ends  6   a ,  6   b ,  12  and  15 . 
     The saddle  19  slides in both directions along the main body  45 , contrasted by the spring  35 . 
     The saddle  19  is connected to arm  2   a  through a connection device  26 , fitted with teeth adapted to engage the rack  8 . 
     This device  26  is meshed in the saddle  19  using rail-type connection means, adapted to remove it from rack  8 , for disconnecting the saddle  19  from arm  2   a , and moving the arm to the desired starting position. 
     The saddle  19 , finally, is also connected to arm  10  using a pawl  27 , fitted with teeth adapted to engage rack  13 , due to the action of a spring  28 . 
     The pawl  27  is also fitted with a pin  29  which slides or rotates along the surfaces bordering the slotted holes  30  and  31 , on the main body of handle  1  and the saddle  19 , as well as with a second pin  32  which slides in slotted hole  33  on saddle  19 , and, if required, horizontally in a slotted hole  50  of the main body  45 , countered by spring  28 . 
     The first pin  29  allows selective engagement of means blocking the pawl  27 , e.g. a hook  36  pivoted to the main body  45  of handle  1 . 
     The second pin  32  is pushed towards the teeth  13  by the spring  28  housed in the main body  45 . 
     In a second version of the tool, as illustrated in FIGS. 5 and 6, the saddle  19  is replaced with a block  37  which slides inside guide  4   b of arm  2   b.    
     This block  37  is connected to manoeuvring lever  16  using a connecting rod  38  and to arm  10  using a rod  39 , at the lower end of which is fastened a rotating reel  40 , a portion of the side surface of which is fitted with teeth  41  engaging the teeth  13 . 
     In this version, arm  10  is inserted into a prismatic guide which is coaxial to that of arm  2   a ; the position of the arm  10  can be selectively blocked as required using a locking device  42  of teeth  13  fixed to the main body  45  of handle  1 . 
     In a further version of the device, which is not illustrated, arm  10  is absent and element  14  is replaced by magnetic fastening means. 
     In the preferred embodiment of the tool, arm  2   a  can be inserted in housing  4   a  by disconnecting device  26 , while arm  2   b  can be directly inserted into housing  4   b.    
     The connecting device  26  also allows the setting of the initial distance between jaws  6   a  and  6   b.    
     Arm  10  can be disconnected (or inserted) from housing  9  by disconnecting pawl  27 , acting on pin  32  which can horizontally slide in slotted hole  33 , against the force of spring  28 . 
     Element  14  can be fastened at the end of the main body  45  of handle  1  using locking elements  48  of known type. 
     Acting on manoeuvring lever  16 , the saddle  19  slides downwards, dragging arm  2   a , whose end  6   a  approaches end  6   b  of lever  2   b , which remains fixed in its housing. 
     At the same time, pin  29  slides along slotted hole  30 , dragged by slotted hole  31 . 
     In this way the toothed side of pawl  27  engaging rack  13  of arm  10 , makes it slide upwards, causing the end  12  to approach the grip portion  15  of element  14 . 
     This movement allows the vice, made up of jaws  12  and  14 , to fasten the tool to a protruding part of a work bench. 
     Lever  16  is kept in position by spike  17  which meshes in the teeth  22  of block  18 , thanks to the action of spring  23 . 
     In this way it is possible to keep a fixed distance both between end  6   a  and  6   b  of gripping arms  2   a  and  2   b , and between the end jaw  12  of arm  10  and the grip portion  15  of element  14 . 
     Reel  24  can be used to adjust the pressure on the object tightened between these elements with greater precision. 
     To fasten the grip of the jaws  10  and  14 , hook  36  acting on pawl  27  can be used. In this way, even further upward movement of saddle  19  will not separate arm  10  from element  14 , keeping the tool fastened to the work bench. 
     As a consequence, the fine adjustment of the pressure between arms  2   a  and  2   b  or  10  and  14 , using reel  24 , can be performed independently, depending on whether the hook  36  is inserted or not. 
     In the second version of the tool, acting on manoeuvring lever  16 , block  37  slides inside housing  4   b , pushing arm  2   b  upwards, whose end  6   b  approaches end  6   a  of arm  2   a.    
     At the same time, rod  39  slides and drags the arm  10 , via reel  40 , whose teeth  41  are meshed in rack  13 . 
     To block the arm  10  and free the movement of arms  2   a  and  2   b  from the movement of arm  10 , the user can turn the reel  40 , so as to disengage teeth  41  from rack  13 . 
     This operation thus allows the upper section of the tool, made up of gripping arms  2   a  and  2   b , to be made independent from the lower portion (or vice), made up of elements  10  and  14 , which can remain closed even when the lever  16  is opened. 
     For removing arm  10  from its housing, the user removes the locking element  42  from rack  13 , after disengaging teeth  41  of the reel  40 . 
     To remove arm  2   a  from its housing  4   a , the user must disconnect the teeth of locking element  43 , fastened in a removable manner to handle  1 , from teeth  8  of arm  2   a.