Abstract:
A nail machine and a tool ring for securing elongate bodies in the manufacture of heads on the elongate bodies. The tool ring has an axis of rotation, an outer circumference and a surface that extends substantially perpendicular to the axis fo rotation, and wherein the tool ring comprises a number of engagement devices spaced substantially equally at the circumference of the tool ring for receiving and releasably securing the elongate bodies. Each of the engagement devices has two mutually opposed holding jaws, at least one of which is movable and arranged on a movement mechanism so that it can be displaced towards and away from the opposed holding jaw. The engagement devices also have two opposed holding trays which are movable towards one another. The movement mechanism is arranged so that it displaces the movable holding jaw in a radial or axial direction relative to the axis of rotation of the tool ring to engage and position the elongate body and then clamp the elongate body by the holding trays with greater force to hold the elongate body securely while the head is formed thereon.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a tool ring for securing preferably elongate bodies in a machine, eg for the manufacture of heads on said elongate bodies, said tool ring having an axis of rotation, an outer circumference and a surface extending substantially perpendicular to the axis of rotation; and wherein the tool ring further comprises a number of engagement means arranged for receiving and releasably securing bodies and spaced substantially equally apart at the circumference of the tool ring, said engagement means each comprising two mutually opposed holding jaws, and wherein at least one of the two holding jaws is/are arranged on a movement mechanism which is arranged to enable the holding jaw to be displaced towards and away from, respectively, the opposed holding jaw. 
     BACKGROUND AND PRIOR ART 
     Such tool ring is known ia from Danish patent Nos 143 935 and 163 111. The tool ring is used in these machines for the manufacture of nails, wherein the tool ring is rotatably suspended about the axis of rotation of the tool ring opposite a wire cutter that serves to cut off elongate wire bodies from a storage of metal wire and shift said elongate bodies onwards for receiving and securing on the tool ring. The tool ring is arranged opposite a second tool ring, the circumference of which corresponds to this tool ring, but it is not provided with engagement means. This second tool ring is also rotatably suspended about an axis of rotation which is substantially coaxial with the axis of rotation of the first tool ring, but having an angulation of a few degrees relative to the axis of rotation of the first tool ring, whereby an elongate body arranged between the tool rings is secured there between in that area where the distance between the tool rings is relatively small, and wherein the elongate body is loosened between the tool rings at the substantially opposite side of the tool rings. 
     In this context, the term ‘nail’ is used to designate any object having a shaft which is, at its one end, provided with a head. 
     In the area where the elongate body is secured between the two tool rings, the wire body is so well secured that it is possible to forge or roll a head onto the one end of the wire body, and for this purpose the tool rings are, at each engagement means, provided with a plurality of opposed pairs of holding trays made of an extremely wear resistant material and each having a groove for receiving the elongate body. Here the engagement means in the tool ring serves to engage with the elongate body and to secure and position it in such a manner that with a high degree of certainty the body will be correctly positioned in the groove in the holding trays when the holding trays closes in on the elongate body. 
     Thus, the known nail machines function by the tool rings being caused to rotate synchronously about their axes of rotation, whereby the individual pairs of holding trays are successively conveyed past the wire cutter that inserts an elongate body between the tool rings, each of said engagement means engaging with and positioning an elongate body between the two tool rings which subsequently, by their rotation, remove the elongate object and lock it between the tool rings, following which a head is rolled onto the one end of the elongate body, and wherein the tool rings subsequently release the elongate body in the form of a nail or the like. 
     It is a problem with these prior art nail machines to control and synchronise the wire cutter to ensure that the individual elongate bodies are reliably introduced between the holding jaws on each of the engagement means, said holding jaws being arranged in or radially opposite the space between the tool rings. In practice, this means that the speed of rotation of the tool rings is restricted by the need for introducing an elongate body during that period of time when the engagement means are positioned directly opposite the wire cutter, and that the productivity can be increased for a given nail machine only if the number of holding trays with accompanying engagement means is increased. In practice this means that the known tool rings typically contain about 20 to 40 sets of holding trays and accompanying engagement means. 
     SUMMARY OF THE INVENTION 
     In the light of this, it is the object of the present invention to provide a tool ring that allows a higher degree of freedom when it comes to obtaining a desired productivity for a given nail machine without necessarily entailing that a given number of holding trays with accompanying engagement means are required. 
     This is obtained by use of a tool ring as described in the introductory part and characterised in that the movement mechanism for displacing at least the one holding jaw is so configured that it displaces the holding jaw completely or partially in a radial or axial direction relative to the axis of rotation of the tool ring. As opposed to the known tool rings, and provided the tool ring is rotated such that the displaceable holding jaw of each pair of holding jaws is located opposite the opposed holding jaw in the direction of rotation of the tool ring, this enables the elongate body to be advanced to the tool ring to occupy a position in which the elongate body can be seized by the holding jaws in the engagement device before said engagement means becomes positioned opposite the wire cutter. This means that, at a given speed of rotation for the tool ring, more time is available for introducing the elongate body whereby the above-described limitation imposed on the productivity obtainable with a given tool ring having a given number of holding trays and accompanying engagement means is eliminated or at least considerably reduced. 
     According to a particularly preferred embodiment of the invention it is obtained that undesired variations in the positioning of the individual elongate bodies due to play, if any, in the movement mechanisms of the engagement means, are eliminated or at least considerably reduced by one of the holding jaws in the engagement means being immovably secured on the tool ring, and by the tool ring being configured for rotation in such direction that the immovable holding jaw in each engagement means is situated opposite the immovably secured holding jaw. 
     Advantageously the engagement means is arranged for receiving and securing the elongate bodies in such a manner that the elongate bodies extend completely or partially opposite that surface of the tool ring which is arranged substantially perpendicular to the axis of rotation, and substantially radially inwards towards the axis of rotation of the tool ring and wherein the movement mechanism is so configured that it displaces the movable holding jaw completely or partially in a direction which is axial in relation to the axis of rotation of the tool ring. Hereby it is accomplished that the individual elongate bodies can be introduced radially between the tool ring according to the present invention and a second tool ring arranged oppositely as described above with reference to the prior art nail machines. 
     According to a particularly simple and reliable embodiment, each of the movement mechanisms in the tool ring is so configured as to comprise a shaft which is rotatably arranged in the tool ring; and the movable holding jaw is arranged on a lever which is secured to the shaft of the movement mechanism and extends radially therefrom; and a cam follower is also mounted on the rotatable shaft. Hereby a movement mechanism is established that comprises only a rotatable bedding of the movement mechanism whereby a mechanism is provided which is relatively maintenance-free. 
     The cam follower is advantageously spring actuated such as to move the movable jaw against the opposed jaw. Thereby no adjustments are necessary in order to produce nails from wires having different diameters. 
     According to a preferred embodiment, the tool ring is so configured that the rotatable shaft of the movement mechanism is arranged such that its axis of rotation points substantially radially inwards towards the axis of rotation of the tool ring. Hereby a movement pattern is obtained for the movable holding jaw that ensures that, in its position near the opposed holding jaw, the movable holding jaw moves substantially in a direction perpendicular to the opposed holding jaw. 
     According to a particularly preferred embodiment, the tool ring has such configuration that the immovably secured holding jaw has a substantially planar holding surface that faces in the direction of rotation of the tool ring; and that the movable holding jaw has a substantially planar holding surface that faces essentially towards the immovably secured holding surface. Hereby adequate attachment of the elongate bodies is obtained which ensures that the bodies are correctly positioned. 
     Furthermore, the present invention relates to a nail machine comprising a tool ring according to the preceding, wherein said nail machine is characterised in comprising a drive device for pulling off a metal wire from a storage, a device for stretching and straightening the wire, a cutter for cutting off desired lengths of elongate bodies of said wire, means for introducing the elongate bodies into the tool ring, a roller for rolling heads onto the elongate body, and means for removing and collecting the elongate bodies provided with heads and to convey said elongate bodies away from the nail machine. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in further detail with reference to the drawings, wherein: 
     FIG. 1 is a perspective explanatory sketch of a prior art nail machine which is known in principle and provided with a tool ring according to the present invention; 
     FIG. 2 a  is a sketch of a section of one embodiment of a tool ring according to the invention, seen radially from the outside of the tool ring; 
     FIG. 2 b  is a front view sketch of the embodiment shown in FIG. 2 a  of a tool ring according to the invention; 
     FIG. 2 c  is a sketch of the embodiment of the tool ring shown in FIGS. 2 a  and  2   b , seen from the centre of the tool ring and radially outwards to the side; 
     FIG. 3 is a sectional view along the line A—A in FIG. 2 b ; 
     FIG. 4 a  is a sketch illustrating a sectional view of a first alternative embodiment of a tool ring according to the invention, seen radially from the outside of the tool ring; 
     FIG. 4 b  is a sketch illustrating a front view of the embodiment of a tool ring according to the invention shown in FIG. 4 a , but where the ring has been straightened for space considerations. 
     FIG. 4 c  is a sketch illustrating the embodiment of a tool ring shown in FIGS. 4 a  and  4   b , seen from the centre of the tool ring and radially outwards to the side. 
     FIG. 5 a  is a sketch illustrating a sectional view of a second alternative embodiment of a tool ring according to the invention, seen radially from the outside of the tool ring. 
     FIG. 5 b  is a sketch illustrating a front view of the embodiment of a tool ring according to FIG. 5 a.    
     FIG. 5 c  is a sketch showing the embodiment of a tool ring in FIG. 5 a  and  5   b , seen from the centre of the tool ring and radially outwards to the side. 
     FIG. 6 a  is a sketch illustrating a sectional view of a third alternative embodiment of a tool ring according to the invention, seen radially from the outside of the tool ring. 
     FIG. 6 b  is a sketch illustrating a front view of the embodiment of a tool ring according to FIG. 6 a.    
     FIG. 7 is a sketch showing the means for introducing the elongate bodies to the tool ring. 
    
    
     DETAILED DESCRIPTION 
     Thus, FIG. 1 illustrates a nail machine  1  comprising a stretching station  2 , through which an arrangement of drive rollers  4  serves to pull a metal wire  3  from a not shown coil of wire, and wherein the metal wire is hereby straightened and stretched to a substantially completely straight piece of wire. After the drive rollers  4 , the metal wire is displaced into a wire cutter consisting of two rotating wire cutters  5 , and from the rotating cutters  5  the pieces of wire  6  cut off the wire  3  are displaced into a tool ring  7  that rotates clockwise in the embodiment shown herein. The individual pieces of wire are secured and positioned by a roller  8  intended therefor, whereby the pieces of wire are caused to extend equal distances towards the centre of the ring. At the lowermost area of the tool ring, a roller  9  is arranged that is configured to co-operate with the tool ring  7  for rolling heads onto the individual pieces of wire  6 . The wire pieces  6  provided with heads are subsequently advanced in the tool ring and upwards to the uppermost part of the tool ring  7 , where the piece of wire provided with head is released from the tool ring and drops down onto a chute  10  that conveys the piece of wire away from the nail machine. 
     The above mentioned tool machine and its functioning are generally known; and the present invention specifically relates to a tool ring that distinguishes itself by increasing the productivity relative to the number of tools arranged in the tool ring compared to the prior art devices. 
     Thus, the following figures illustrate specific embodiments of the invention in the form of tool rings that may, in principle, successfully be used in connection with the machine shown in FIG.  1 . 
     Thus, FIGS. 2 a ,  2   b  and  2   c  outline a first embodiment of a tool ring  7  according to the invention, wherein FIG. 2 a  is a sectional view of an embodiment of a tool ring according to the invention, seen radially from the outside of the tool ring. As will appear three identical sets of holding jaws are shown that each comprises a fixed holding jaw  11   a ,  11   b ,  11   c , respectively, mounted on the tool ring  7  and a second movable holding jaw  12   a ,  12   b ,  12   c  that may rotate about an axis perpendicular to the plane of the paper. The holding jaw  12   a  is shown in the position it occupies before the holding jaws  11   a  and  12   a  are opposite the spot where a piece of wire  6  is inserted towards the tool ring  7 . As will appear, in accordance with the present invention the movable holding jaw  12   a  is, in this position, displaced axially relative to the axis of rotation of the tool ring such that it is drawn down below the plane defined by the surface  13  of the tool ring  7 , whereby a cut-off piece of wire  6  can be inserted to the tool ring across the surface  13  on the tool ring  7  soon enough for the movable jaw to be able to pass the piece of wire  6  without touching it. 
     The holding jaws  11   b  and  12   b  are subsequently shown in a second position, following insertion of a piece of wire  6  to the tool ring  7 , and wherein the movable holding jaw  12   b  has been pivoted such as to press the piece of wire  6  towards the fixed holding jaw  11   b . Finally, the same position is shown illustrated at the holding jaws  11   c  and  12   c.    
     Now FIG. 2 b  illustrates the same positions as shown in FIG. 2 a , only as front views on the tool ring  7 , perpendicular to the surface  13 . The arrow A in FIG. 2 b  illustrates the direction of rotation of the tool ring. It will further appear that the holding jaws  12   a ,  12   b  and  12   c  are moved by means of a cam device  14  mounted on the frame of the nail machine and respective cam followers intended for each of the holding jaws  12   a ,  12   b  and  12   c  in the form of a roller  15   a ,  15   b ,  15   c . The principle behind the movement mechanism shown will now be described in further detail below with reference to FIG.  3 . 
     FIG. 2 c  also illustrates the same positions of the holding jaws as seen in FIGS. 2 a  and  2   b , but seen from the centre of the tool ring  7  and radially outwards. Here the cam device is seen in a lateral view; and it will appear that the cam device has a ramp  16  that brings about the movement that the movable holding jaws perform from the position illustrated at the holding jaw  12   a  in FIG. 2 a  to the position illustrated at the holding jaw  12   b.    
     Now, FIG. 3 illustrates a preferred embodiment of the movement mechanism of the movable holding jaw  12   a ,  12   b  and  12   c  shown in FIGS. 2 a  through  2   c . A piece of wire  6  is shown which has been introduced between the tool ring  7  according to the present invention, and a second, opposed tool ring  17 . In the tool ring  7 , a holding tray  18  is arranged which is provided with a groove  19 , and in a similar manner a corresponding holding tray  20  with a groove  21  is arranged in the opposed tool ring  17 , and the two holding trays  18  and  20  are, during rotation of the tool rings  7 ,  17 , squeezed together with great force around the piece of wire  6 , this causing the latter to be secured relative to the tool rings  7 ,  17 . However, the holding trays are unsuitable for quickly seizing and securing a piece of wire  6 , and therefore the use of such tool rings presupposes a further engagement device for seizing and positioning the piece of wire relative to the grooves  19 ,  21  on the holding trays  18 ,  20 . The engagement device shown in FIG. 3 corresponds to the one shown in FIGS. 2 a  through  2 C and, and as mentioned in connection with said figures, it features a fixed holding jaw (not shown in FIG. 3) and a movable holding jaw  12   c  arranged on a lever  22  that extends radially outwards from a first extremity of a shaft  23  which is mounted pivotally in the tool ring  7 . 
     At the other extremity of the shaft  23 , a cam follower is arranged that comprises a cam roller  15   c  extending on a cam device  14  arranged along the internal periphery of the tool ring  7 . Between the cam follower  23  and the tool ring  7 , a torsion spring  24  is arranged which is biased so as to constantly aim at keeping the cam follower in abutment on the cam device, and pulling the holding jaw  12   c  away from its opposed, fixed holding jaw  11   c . Moreover, the cam follower with the cam roller  15   c  is arranged to be rotatable on the shaft  23 ; and between the cam follower and the shaft, a torsion spring is arranged, said torsion spring being biased in such a manner that it seeks to bias the holding jaw  12  towards its oppose holding jaw  11   c.    
     Thus, a movement mechanism is provided which serves to provide, throughout the major part of its movement range, a rigid transmission of force between the cam follower and the holding jaw; and wherein the torsion spring  24  works alone. However, an impact spring  25  is arranged having a spring constant that substantially exceeds the spring constant of the torsion spring  24 ; and wherein it is the sole purpose of the impact spring  25  to ensure that the abutment pressure between the holding jaws  11   c  and  12   c  and the piece of wire  6  is limited, since the cam follower is able to rotate relative to the shaft  23  against the spring force of the impact spring. 
     Now FIGS. 4 a  through  4   c  illustrate an alternative embodiment of the present invention wherein FIG. 4 a  is a front view sketch that illustrates a section of a first alternative embodiment of a tool ring according to the invention seen radially from the outside of the tool ring; and FIG. 4 b  is a sketch that illustrates a front view of the embodiment of a tool ring according to the invention shown in FIG. 4 a , but wherein the ring has been straightened for space reasons; and FIG. 4 c  is a sketch illustrating the embodiment of a tool ring shown in FIGS. 4 a  and  4   b , seen from the centre of the tool ring and radially outwards to the side. 
     Thus, FIG. 4 a  illustrates a tool ring  7  with an alternative configuration of the movement mechanism for the holding jaws: The tool ring is arranged to rotate in the direction indicated by the arrow B, and it will appear that this configuration is so arranged that each of the holding jaws of an engagement device is arranged to be movable relative to the tool ring  7 . The holding jaw  26  is displaceably arranged in a parallel guide, and the holding jaw  27  is pivotally arranged in a bearing in the tool ring  7 . In accordance with the principle behind of the invention, the two holding jaws  26  and  27  can be moved partially axially relative to the axis of rotation of the tool ring, and the movement pattern of the holding jaws  26  and  27  is illustrated by five different positions by means of a toothed wheel  28  arranged in the tool ring  7  and co-operating with a toothed bar arranged on the holding jaw  26 , and an annular toothing on the holding jaw  27 , whereby both holding jaws  26  and  27  can be moved by means of one and the same toothed wheel. 
     As will appear from FIG. 4 a , the holding jaw  27  thus moves down below the surface  13  on the tool ring  7  in those positions where the piece of wire  6  is introduced to the tool ring  7 , as will appear from FIG. 4 b . Thereby the piece of wire  6  can, in accordance with the effect of the present invention, be introduced over a relatively protracted period of time without coming into contact with the holding jaw  27 . 
     As will appear from FIG. 4 c , the toothed wheel  28  is activated as a consequence of a cam follower and a cam device being provided on the internal periphery of the tool ring  7  which, in principle, corresponds to the device shown in FIGS. 2 b  and  2   c.    
     On FIGS. 5 a  through  5   c  is further illustrated a second alternative embodiment of the present invention, comprising a tool ring  7  having a further alternative construction of the movement mechanism for the movable jaw  29 . As can be seen from the figures the movement mechanism comprises a cam  14 , a number of jaws  29  being pivotally arranged on an axle and wherein each axle has a cam follower  15  to engage the cam  14 , so as to bring the movable and the opposed stationary jaw  31  into a closed and open position respectively. 
     A compression spring  30  is mounted such as to engage the cam follower  15  such as to urge the movable jaw into its closed position in which it presses against the stationary opposed jaw  31 . 
     In this way the compression spring provides the holding force for holding the elongate bodies between the jaws  29 ,  31 , and thereby no specific adjustments are necessary for shifting between producing e.g. nails from wires having different diameters. 
     FIGS. 6 a  and  6   b  show a third alternative embodiment of the invention, in which the movable jaw is not moved axially beneath the surface of the tool ring  7 , but as an alternative solution is rotated about an axle being substantially parallel to the axis of rotation of the tool ring. 
     On FIG. 7 is disclosed a preferred embodiment of the invention in which the elongate bodies are introduced into a tool ring  7 , and wherein the means for introducing the elongate body comprises a rotating cutter having two rotating cutting cylinders  34  for cutting the elongate bodies  6  from a wire  35 . From the cutting cylinders  34 , the elongate bodies are forwarded in between a number of rotating roller pairs  36 , and the rotating roller pairs are rotating in a direction so as to accelerate the elongate bodies  6  in order to forward the elongate bodies  6  into the tool ring  7 . As can be seen from the figure the rotating roller pairs are only engaging the elongate bodies at one single point when the elongate bodies are relatively short. This gives rise to the problem that the elongate bodies may not be correctly inserted in to the tool ring, and thereby the risk of severe damages to the nail machine. 
     In the embodiment disclosed in FIG. 7, this is avoided by the use of a guiding surface  37  for the elongate bodies, the guiding surface having an angle with respect to the axis of rotation of the rotating roller pairs  35  being different from 90°, so that the rotating roller pairs cause the elongate bodies to press and slide against the guiding surface, and thereby the elongate bodies are stabilized. 
     Obviously, the present invention can be exercised in other manners than those shown as preferred embodiments in the drawings and explained above. Thus, the invention is also useful in connection with nail machines equipped with other types of wire cutters, etc. As regards the holding jaws, they may also have a configuration which is different from the ones shown herein, but such that their movement pattern includes at least an axial or radial movement constituent.