Patent Publication Number: US-7708624-B2

Title: Clip machine comprising a closure lever and a process for the production of a closure lever

Description:
This patent application claims priority to German patent application DE 10 2005 025 173.0-27, filed Jun. 1, 2005, hereby incorporated by reference. 
   TECHNICAL FIELD 
   The present invention relates to a clip machine, and in particular to a clip machine comprising at least one closure lever which has a bearing element defining a pivot axis, a receiving element for a first closure tool and a force application element for connection to a drive element, wherein the closure lever is mounted pivotably between an open position and a closed position, in which closed position the first closure tool can be brought into engagement with a second closure tool to close a clip. The invention further concerns a process for the production of such a clip lever as well as the use of such a clip lever in a clip machine for portioning sausages. 
   BACKGROUND OF THE INVENTION 
   Clip machines of the specified kind are used typically for portioning and closing sausages with a liquid to a firm pasty or even granular content. In that operation firstly the filling material is introduced into a tubular case (skin) and thereafter divided up into portions in a first working cycle by means of displacement elements. For that purpose the displacement elements constrict the tubular case in the radial direction and displace the filling material which is in the constriction region in the axial direction—with respect to the axis of the tubular case. A tubular plaited end portion is thus formed in the constriction region. In the next working cycle one or optionally two closure elements (clips) are applied to the tubular plaited end portion formed in that way, by means of two (or four respectively) closure tools which are moved towards each other, and the closure elements are closed around the plaited end portion. The closure tools respectively include in paired relationship a male die and a female die, between which the clip is shaped around the sausage during the closure operation. In the case of two clips which are closed around the plaited end portion in mutually juxtaposed relationship (dual clip arrangement) the plaited end portion can be severed therebetween by means of a blade in order to separate the sausages. Thereafter the displacement elements, the closure tools and the blade are moved back into their starting or open position. A working cycle is thus concluded. The description hereinafter relates to the simple arrangement of a pair of closure tools. It can however be readily applied to a dual clip arrangement. 
   At least one of the closure tools (male die and/or female die) is mounted to the closure lever described in the opening part of this specification and effects thereby during the closure process a pivotal movement which is substantially radial—with respect to the axis of the tube—around the pivot axis. At the same time and/or subsequently to the pivotal movement effected by the closure lever with closure tool from the open position thereof into the closed position thereof, the second closure tool is also brought into engagement with the first closure tool to close the clip or clips, in a pivotal movement or a linear movement or a combination of both forms of movement. 
   In such clip machines, there is generally provided a cam drive which takes off the movement of the closure lever from a cam disk by means of a cam roller. The drive element typically provided is a lever arrangement which transmits that movement to the closure lever. As an alternative or in addition to the cam drive the assembly may also have a linear fluid drive, typically a pneumatic drive. 
   In that case very high forces (up to 15 kN) are applied to the closure lever or levers by way of the closure tools. On the one hand that results in a production of noise which is unpleasant to the operating personnel while on the other hand it means that the closure lever must be of sufficiently great dimensions for it to withstand the loading. The latter in turn results in the closure lever being of a great weight and thus results in a high mass moment of inertia. As the motor drive including all drive elements (cam disk, cam roller and lever arrangement) cannot be designed to be of just any size that may be desired, the operating speed of the clip machine also cannot be readily increased. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is to improve a machine of the kind set forth in the opening part of this specification in such a way that the efficiency of the clip machine can be increased without the drive being of a more powerful design configuration. 
   The closure levers were produced in known manner from cast aluminum. Besides the above-indicated disadvantages that also had the consequence that the bearing element, the receiving element and the force application element as well as other functional elements such as cams or running surfaces and mounting points can only be produced with the necessary precision on the casting by post-machining. In comparison the closure lever of fiber-reinforced plastic composite (FRPC) is produced in accordance with the process of the invention in one piece completely ready for use. The necessary precision is afforded by the prefabricated casting mold in which the bearing element, the receiving element, the force application element and optionally further functional elements are so laid that the pivot axis, the force application point, the receiving means for the first closure tool and the like are oriented relative to each other within the allowable tolerance, without post-machining. 
   The considerably lower specific density of the fiber-reinforced plastic composite, particularly when using a carbon fiber-reinforced plastic (CFRP) means that the mass moment of inertia of the closure lever can be reduced by about 30% at least while retaining and in part even when improving the mechanical load-bearing capability. This means that all drive elements are smaller and lighter in dimension to a corresponding degree and the costs of the overall clip machine can be reduced or the working speed of the clip machine can be increased with the dimensioning of the drive elements remaining the same. The use of a FRPC material, because of different resonance properties, also means that the abrupt closure movement of the closure tools experiences an acoustic damping effect, whereby the closure operation represents only an insignificant acoustic loading for the operating personnel. Furthermore the use of an FRPC material and in particular the use of CFRP is advantageously found to be foodstuffs-compatible, sterilizable, temperature-resistant, chemical-resistant (in particular resistant to cleaning agents) and high pressure-resistant. In comparison with the aluminum castings which as is known were used at that location, the surface of the closure lever according to the invention of FRPC material is per se smooth. That makes it possible to save on a further post-machining operation without disregarding the hygiene conditions which are to be observed in the area of foodstuffs processing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features and advantages of the clip machine according to the invention are set forth in the appended claims. They are described hereinafter with reference to the accompanying drawings in the following description of an embodiment by way of example. In the drawings: 
       FIG. 1  shows a diagrammatic side view of the moved elements of an embodiment of the clip machine according to the invention, 
       FIG. 2  shows a side view of an embodiment of a closure lever in the clip machine, 
       FIG. 3  shows a perspective view of an embodiment of the closure lever according to the invention, and 
       FIG. 4  shows an exploded view of the individual components of the clip lever shown in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE DRAWINGS 
   The embodiment shown in  FIG. 1  of the clip machine  100  according to the invention has a clip machine drive  110  with a cam disk  112 , from which the movement is taken for a lower closure lever  118  by means of a cam roller  116 . In addition the clip machine has a further clip machine drive with a crank  130 , from which the movement for an upper closure lever  120  is taken by means of a lever arm  114 . In the illustrated embodiment, the two closure levers  118 ,  120  are mounted pivotably about the same pivot axis  122 . At its end remote from the pivot axis  122  the lower clip lever  118  carries a first closure tool  124  which is a female die in the illustrated embodiment. At the same spacing relative to the pivot axis  122  the upper clip lever  120 , at its end opposite to the pivot axis  122 , carries a second closure tool  126  which is here a male die. 
   The lower closure lever  118  pivots upwardly about the common pivot axis  122 , driven by way of a lower elbow lever arrangement as a drive element, when the elbow lever pivot of the lower elbow lever is straightened by a force applied by way of a coupling rod. In a corresponding manner but in time-displaced relationship the upper clip lever  120  pivots downwardly about the common pivot axis  122 , driven by way of an upper elbow lever arrangement as a drive element, when the elbow lever pivot of the upper elbow lever arrangement is straightened by a force applied by way of a coupling rod. That causes the female die  124  and the male die  126  to be moved towards each other in order in the closed position thereof to be able to close a clip around the previously constricted tubular case (not shown). By virtue of the phase-displaced cams for the upper clip lever drive and the lower clip lever drive on the cam disk  112 , the lower closure lever  118  is already in its upper closed position and remains there for a short moment while the upper closure lever  120  continues to move in a direction towards the lower clip lever. In that situation a clip introduced into the female die is firstly severed from a following line of clips and is gripped between the female die  124  and the tubular plaited end portion (not shown) and held in that fashion. When the upper clip lever  120  also approaches its (lower) closed position, the clip is closed around the constricted tubular case. When the clip lever  120  has moved into its closed position a pulse triggers actuation of the piston-cylinder arrangement which—in the case of the dual clip arrangement present here—drives a blade in order to sever the tubular plaited end portion between the two closed clips. After that the upper and the lower closure levers  118 ,  120  pivot back into their open positions. 
   By virtue of the high force which is required to close the clip and the high moment which results therefrom and which acts on both closure levers  118 ,  120 , both closure levers  118 ,  120  must be of very great strength. On the other hand, both levers must perform a sufficiently large pivotal movement so that even sausages of large size can be conveyed through between the closure tools  124 ,  126  during the filling operation in a direction of movement perpendicular to the plane shown in  FIG. 1 . The lower closure lever  118  according to the invention enjoys sufficient strength while nonetheless being of comparatively low weight and thus involving a low mass moment of inertia about the pivot axis  122 , if the lower closure lever  118  is at least partially made from a fiber-reinforced plastic composite. Depending on whether the arrangement has one or two closure levers and depending on how the pivotal movement is distributed to the closure lever or levers, it may be sufficient for one closure lever to be partially made from an FRPC material, or also both. 
     FIG. 2  is a side view of an embodiment of such a lower closure lever  200 . It has a main body  210  which extends substantially in the plane of the illustration. A bearing element  212  is let into that main body and it includes a first metallic bearing receiving means. That bearing receiving means has rotation-preventing means for example in the form of notches or projections, which prevent the bearing element  212  from turning in the FRPC material. Also let into the main body  210  are a receiving element  214  for positioning and holding the first closure tool or tools, and a force application element  216  for connection to the drive element. Both the receiving element  214  and also the force application element  216  are preferably let into the main body  210 , in the form of a metallic insert. In addition the main body has openings  218 , by which the weight of the closure lever  200  is reduced without however dropping below the predetermined limit in respect of stability of the closure lever. Instead of or in addition to the apertures shown in  FIG. 2 , the openings  218 , in a similar or different arrangement, may also include pockets which are not right through and which transmit the flow of force in a possibly different fashion, but also with the proviso of adequate stability. 
   The embodiment of the lower closure lever shown in  FIG. 3  shows as a perspective view that, besides the main body  310 , there is also a cranked cantilever arm  312  which is connected at one end  313  to the main body  310 . The cranked cantilever arm  312  thus projects out of the plane defined by the main body  310 . In this embodiment the mounting element  322  comprises a metallic bearing receiving means  324  which is let into the main body  310  from one side so that the first bearing receiving means  324  projects out of the plane of the main body  310  on the side in opposite relationship to the cranked cantilever arm  312 . In addition the bearing element  322  comprises a second metallic bearing receiving means  326  which is let into the cranked arm  312  in coaxial relationship with the first metallic bearing receiving means  324 . Those bearing receiving means provide that the bearing support effect can be implemented over such a long axial portion that the closure lever can withstand relatively high flexural moments in the axial direction. 
   In the process according to the invention for the production of such a clip lever, for example in the preform RTM production process, the operation of letting the insert portions into the lever is effected by laying the bearing element  212 ,  312 , the receiving element  214 ,  314  and the force application element  216 ,  316  in a molding tool in which moreover the main body  210 ,  310  and possibly the cantilever arm  312  is built up in layer-wise fashion from layers of preformed fiber mats, of a carbon fiber cloth. The molding tool is then closed and a liquid plastic (for example epoxy resin) is injected under high pressure into the mold until the mold is filled. After the plastic sets the mold can be opened and the finished closure lever  200 ,  300  can be removed. The insert portions are involved in a positively locking join to the stabilising fiber mats, by means of the hardened plastic. The way in which the stability of the positively locking join can be still further increased will be described in greater detail with reference to the embodiment in the exploded view in  FIG. 4 . 
     FIG. 4  shows all elements of the closure lever according to the invention. Firstly the closure lever elements which are built up in layer-wise fashion from fiber mats will be described, namely the main body  410  and the cranked cantilever arm  412  connected to the main body at one end. Both the main body and also the cantilever arm of the closure lever are composed layer-wise of a lower portion  414  of preshaped fiber mats, an upper portion  416  of preformed fiber mats and a central portion  418  also of preformed fiber mats. In that case the main body  410  is made up on the one hand in layer-wise fashion from the lower portion  414  and a lower part of the upper portion  416  and on the other hand it is made up layer-wise from the lower portion  414  and a lower part of the central portion  418 . The cranked cantilever arm  412  which at one end is connected to the main body  410  and at its other end projects out of the plane of the main body  410  is in turn built up layer-wise from an upper part of the central portion  418  and an upper part of the upper portion  416 . That sandwich form provides that the main body  410  and the cantilever arm  412  are joined throughout by virtue of interconnected fiber mats, which imparts a high level of stability to the closure lever. Stability is further increased by a cover layer  420  which is formed from preformed fiber mats and which is applied to the respective lower parts of the upper portion  416  and the central portion  418  on the side in opposite relationship to the lower portion  414 . That compensates for the weakening effect caused by the main body  410  being divided into two in the upper layers thereof. 
   In addition further functional elements such as for example a spacer plate  422  of FRPC is laminated on the top side of the main body  410 . Such functional elements can be laminated in position at any location, depending on the respective structural demands on the closure lever. In a corresponding manner, it is also possible to provide openings, apertures, pockets or the like by suitably cutting the preformed fiber mats. 
   As in  FIG. 3  the bearing element comprises the metallic bearing receiving means  424  in the main body  410 , which projects out of the plane thereof on the side in opposite relationship to the cranked cantilever arm  412 , and the second metallic bearing receiving means  426  which is let into the cranked arm  412  in coaxial relationship with the first metallic bearing receiving means  424 . Both bearing receiving means  424 ,  426  have both axial and also radial means for preventing rotation and pulling displacement respectively. They can be provided in the form of notches, grooves, peripherally extending channels or corresponding projections, into which the liquid plastic penetrates in the operation of filling the injection molding mold and thus involve a positively locking join to the metal part. 
   At its end of the closure lever in opposite relationship to the bearing element, the metallic receiving element  428  is let into the main body  410  of the closure lever. The receiving element  428  has a receiving portion  430  for the first closure tool (not shown here), which projects out of the FRPC material, and an anchorage portion  432  which is let in position substantially in the plane of the main body  410  between the lower portion  414  and the upper portion  416 . Provided for that purpose is a corresponding opening  434  in the lower portion  414  and/or in the upper portion  416 . In order further to improve the fixing of the receiving element  428  it can be anchored transversely with respect to the plane of the main body  410  by the anchorage portion  432  with fixing means  436  which for example can be in the form of bolts or screws. 
   In addition the force application element in the form of a metallic insert portion  438  is also let into a corresponding opening or pocket in the upper portion  416  and the cover layer  420 . For the purposes of stabilisation and mechanically securing the metallic insert portion  438  disposed on the opposite side of the main body  410  is a corresponding counterlocking plate  440  which is connected to the insert portion  438  through the lower portion  414  of the main body  410  with fixing means  442  (for example by screwing) and thus involves a positively locking connection to the FRPC main body  410 . 
   All fitting means, bores, screwthreads, cams and the like can already be prefabricated in all functional elements like the bearing element, the receiving element and the force application element. The fact that the functional elements are fitted into the molding tool in accurately fitting relationship means that the dimensional tolerances are observed between the individual functional elements and thus between the measurement points, within the prescribed tolerances.