Abstract:
A tool having relatively movable working elements which are movable with respect to one another by relative movement of a pair of arms or handles wherein a spring element formed from a material consisting of a flexible polymer or elastomer is secured intermediate the arms to thereby provide a damping force opposing selectively movement of the arms toward one another.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a tool, of the type comprising an arm or handle which has a metal part and which, when the tool is used, is brought closer to an element opposite, particularly consisting of a base or of another arm or handle of the tool, and a damping and/or opening spring. 
     2. Discussion of the Related Art 
     The invention applies particularly to the various types of pliers (flat-nose or round-nose pliers, so-called combination pliers, side cutters, etc.), to secateurs and to tools comprising a relatively long arm or lever articulated by one end to a base, such as shears, guillotines, ricers, etc. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a damping and/or opening spring which, although particularly economical, can be passed on in varying forms suited to predetermined behaviour during use of the tool, and which can also act as a member for positioning and/or limiting the extent of opening of the arm with respect to the element opposite. 
     To this end, the subject of the invention is a tool of the aforementioned type, characterized in that the spring comprises a spring-forming part based on flexible polymer or elastomer, which flexes and/or compresses as the said arm is brought closer, and the ends of which are secured respectively to the arm and to the element opposite. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention will now be described with reference to the appended drawings, in which: 
     FIG. 1 is a view, in part section, of a pair of flat-nose pliers in accordance with the invention; 
     FIGS. 2 and 3 are views in section, respectively, along lines II—II and III—III of FIG. 1; 
     FIG. 4 is a view similar to FIG. 1 of a pair of round-nose pliers constituting an alternative form; 
     FIG. 5 is a partial view with part section of another embodiment; 
     FIG. 6 is a view in section along line VI—VI of FIG. 5; 
     FIG. 7 is a view similar to FIG. 5 of an alternative form; 
     FIG. 8 depicts, in longitudinal section, the spring for the pliers of FIG. 7; 
     FIG. 9 is a view similar to FIG. 5 of another embodiment; 
     FIG. 10 is a view similar to FIG. 1 of a pair of combination pliers in another embodiment of the invention; 
     FIG. 11 is a view similar to FIG. 1 of a pair of side cutters according to another embodiment of the invention; 
     FIG. 12 depicts another pair of side cutters according to the invention; 
     FIG. 13 depicts the spring for the pliers of FIG. 12; 
     FIG. 14 depicts in perspective the spring for the pliers of FIGS. 1 and 4; 
     FIGS. 15 to  20  depict various profiles forming alternative versions of the spring of FIG. 16; 
     FIG. 21 is a perspective view of yet another spring according to the invention; and 
     FIG. 22 depicts the profile of another embodiment of the spring in accordance with the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 depicts a pair of flat-nose pliers  1  consisting of two metal limbs  2 , two sheaths  3  and a spring  4 . 
     Each metal limb  2  defines a handle arm  5  and a flat nose  6 , the two limbs  2  being articulated to one another in the manner of a pair of scissors in an intermediate region or joint  7 , in the conventional way, by means of a rivet or the like, not depicted. 
     Each sheath  3  is a molded plastic component which, starting from its distal end, exhibits a blind passage  8  which fits snugly over a handle arm  5 . 
     As can be seen in FIGS. 1 and 2, over a limited length from its distal end, each passage  8  is enlarged towards the mid-plane P of the pliers, that is to say towards the other handle, by a lateral gusset  9  of rectangular cross section. 
     In the example depicted, the passage  8  has a more or less semicircular cross section and the diameter of the semicircle forms a long side of the rectangular cross section of its gusset  9 . 
     The spring  4  is depicted in perspective in FIG.  14 . 
     It consists of a strip of thermoplastic, for example polyacetal, or of vulcanized or thermoplastic elastomer. This strip has a rectangular cross section of constant width l, with a central region  10  whose thickness e 1  is greater than the thickness e 2  of each end part  11 . 
     When the spring is in the as-fitted condition, each part  11 , which forms a part for attaching the spring, fits with a small amount of clearance into a gusset  9 , the part  10  facing away from the joint  7 . 
     Thus each part  11  is in contact, on the one hand, with the inner face of the arm  5  and, on the other hand, with the three walls of the gusset  9 , and it is pushed into this gusset until the shoulder  12  which separates it from the central part  10  presses on the mouth of the gusset. 
     Thus, at rest, the spring  4  tends to resume its original planar configuration, and therefore urges the two arms  5  towards their wide open position, or even as far as this position, as depicted in FIG.  1 . 
     When the user brings the arms  5  closer together, he causes the thick part  10  to bend against its elastic straightening force. 
     It will be understood that the stiffness of the spring  4  can be adjusted through the choice of length and thickness of the spring-forming part  10 . 
     Furthermore, the spring  4 , being made of an insulating material and forming a bridge between the sheaths  3  which are themselves insulating, provides the user&#39;s fingers with good protection against electric shock. 
     In the alternative form of FIG. 4, applied to a pair  1 A of round-nose  6 A pliers, the blind gussets  9  start from a point some way along the sheath  3 , which at this point has an internal lateral opening  13 , and they extend towards the distal end of the sheath, as far as a short distance from this end. 
     As an alternative, the gussets  9  may also open onto the distal end of the sheath. 
     The spring  4  is the same as before, but its central part  10  has an increase in thickness towards the joint  7 . Consequently, each attachment part  11  is introduced into the associated gusset  9  until the shoulder  12  presses against the distal edge of the opening  13 . 
     As before, bringing the arms  5  closer together stresses the spring  4  in bending, and this spring tends to straighten itself and return the pliers to or towards their wide open position of FIG.  4 . 
     In the example  1 B of FIGS. 5 and 6, the sheath  3  has on its inside an increase in thickness  14  which ends in a shoulder  15  a certain distance from the distal end of the sheath. Projecting from this shoulder is a cylindrical stud  16 . The spring  4 B is a tube made of flexible plastic, for example of circular cross section, the end parts  11 B of which fit with a small amount of clearance onto the stud  16  until they press against the shoulder. 
     The tube is then externally in contact with the arm  5 . Its central spring-forming part  10 B has, as was the case in FIG. 1, a bowed shape with the concave side away from the joint  7 , and it tends to straighten itself, thereby opening the pliers. 
     The alternative form  1 C in FIGS. 7 and 8 differs from the previous one in the following two respects. 
     On the one hand, the stud  16  projects towards the proximal end of the sheath, in an inside lateral recess  17  thereof, the shoulder  15  being defined on a distal end part  18  of this sheath. 
     On the other hand, the spring-forming central part  10 C of the spring  4 C has the shape of a solid rod, while the two end parts  11 C, of the same external cross section, are tubular and fit as before onto the studs  16  until they press on the shoulders  15 . 
     Choosing a tubular  4 B or partially tubular  4 C spring, in each of the configurations of FIGS. 5 and 7, makes it possible to define the stiffness of the spring. 
     FIGS. 9 to  11  illustrate three other embodiments of the invention. 
     In the case of FIG. 9, the spring-forming part  10 B of the spring  4 D is a bow, the concave side of which faces away from the joint  7  and which is moulded integrally with the two sheaths  3 . 
     As an alternative, the concave side could, of course, face the joint, as depicted in chain line. 
     The examples of FIGS. 10 to  12  make it possible to obtain at least two different spring stiffnesses while the two arms  5  are being brought closer together. 
     In the pliers  1 G of FIG. 10, which are depicted as combination pliers, the spring  4 G differs from the spring  4  in FIG. 1 in that its intermediate part  10 G is in the shape of a Ω and extends right up close to the joint  7 . 
     Consequently, as the arms  5  start to be brought closer together, the two lower or proximal legs  23  of the Ω are straightened out downwards, which causes a relatively weak initial elastic effect. Next, the top of the Ω comes into contact against the joint  7 , and continuing to bring the arms  5  closer together not only continues to straighten out the legs of the Ω but also begins to flatten its loop. The spring stiffness is thus increased. 
     In the embodiment of FIG. 11, applied to side cutters  1 H, use is made of the spring  4 A of FIG. 4, deformed by pushing its central part  10 A towards the joint  7 , which gives the spring a W shape. 
     As the two arms  5  start to be brought closer together, the spring therefore experiences threefold bending, at the points  24  to  26 , which provides a first stiffness, greater than that of the spring  4 A of FIG.  4 . Next, the central part  10 A is trapped, folded, between the inner faces of the two sheaths  3 , just before the pliers are fully closed. Closure is therefore completed while at the same time compressing the plastic elastomer on itself, which produces distinctly stronger elastic resistance. 
     The effect thus obtained is one of damping the final manual effort, which avoids the user feeling a jolt in his hand when cutting through a metal wire or the like. 
     As depicted in chain line in FIG. 11, it is possible to envisage using the same spring  4 A in the W configuration and in the simply bowed shape of FIG. 4, either in different pairs of pliers or in the same pair of pliers. The user can therefore choose a single stiffness or two successive stiffnesses for each use of the pliers. 
     As an alternative, one or all of the curvatures of the spring may be reversed, like in FIG. 1, it then being possible for the spring to adopt an M shape. 
     Also an alternative, if, in the W- or M-shaped configuration, the central part  10 A is not trapped at the end of closure, the user may simply choose between a low stiffness (bowed shape) and a greater stiffness (W or M shape). 
     A similar effect of two successive stiffnesses is achieved using the side cutters  1 I of FIG. 12, in which the spring  4 I depicted alone in FIG. 13, is a strip of plastic or elastomer which close to each end has an aperture  27  which fits over an arm  5  and is placed just before the distal end of the sheath  3 . The spring thus has the overall shape of a pair of spectacles. The central part  10 I is bent into a V. 
     During the first part of the travel of bringing the arms  5  closer together, the part  10 I is stressed in bending, which produces relatively weak elastic resistance. 
     Shortly before the fully closed position, as depicted in FIG. 12, the part  10 I, completely folded, is trapped between the distal ends of the two sheaths  3 , and this causes the material of the spring to be compressed onto itself and produces greater elastic resistance. 
     As an alternative, as shown in chain line in FIGS. 12 and 13, the end parts  11 I of the spring  10 I may be extended to form external guards  28  for the user&#39;s fingers. In this case, the parts  11 I may be curved and shaped to fit in with the appearance of the distal part of the sheaths  3 . 
     FIGS. 15 to  22  depict, in side view, the profiles of various springs which can be fitted to the pliers  1  or  1 A of FIGS.  1  and  4 : 
     FIG.  15 : the central part  10  has an increase in thickness on both sides of the spring; 
     FIGS.  16  and  17 : the central part  10  is domed and meets the attachment parts  11  with a continuous curvature, without forming a shoulder. The increase in thickness may be on both sides (FIG. 16) or on just one side (FIG.  17 ); 
     FIGS. 18 to  20 : the central part  10  is connected to the end parts  11  by undercut shoulders (FIG.  18 ), or alternatively sloping shoulders (FIG.  19 ), or alternatively by two rounded portions (FIG.  20 ); 
     FIG.  21 : the central part  10 J of the spring  4 J has a cutout  29  mid-way along its length, so that beginning to fold this part  10 J provides relatively weak elastic resistance then, when the flanks of the cutout  29  come into mutual contact, the elastic resistance is markedly increased; 
     FIG.  22 : the central part  10 K of the spring  4 K has a greater thickness at its two ends  30  than at any intermediate point. Consequently, as the arms  5  are brought closer together, there is first of all a simple bending of the part  10  (relatively weak elastic resistance), then, when the ends  30  come into mutual contact, there is compression of the material of the spring (markedly greater elastic resistance). 
     In alternative forms which have not been depicted, the spring-forming part can be over molded onto one or both attachment parts made of some other material, particularly a metallic one.