Patent Publication Number: US-6339942-B1

Title: Compound needle with asymmetrically divided closing element

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the priority of German Application No. 199 50 259.5 filed Oct. 18, 1999, which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a compound needle, having the features as defined in the preamble to patent claim  1  or patent claim  2 . 
     Compound needles, such as the ones used for flat knitting machines or circular knitting machines, consist of a needle member with a closing element channel, inside of which a closing element is positioned such that it can be displaced. A needle head in the form of a hook is formed onto the free end of the needle member. The hook can be opened or closed by the closing element. The knitting machine comprises at least one flat or one cylinder-shaped and/or one plate-shaped needle bed containing respectively several needle channels. The compound needles are arranged inside these needle channels such that they can be displaced in longitudinal direction, wherein they perform a back-and-forth movement in longitudinal direction during the knitting operation. The closing element must perform a coordinated back-and-forth movement, for which it is provided with a so-called butt that functions as a means for transmitting movement and makes contact with curved surfaces. Curved surfaces of this type are, for example, the flanks of a so-called cam channel. 
     During the knitting operation, the head as well as the closing element of the compound needle come in contact with the yarn. As a result, dust or filament particles can be deposited on the closing element, depending on the composition of the yarn as well as the amount of dirt that is carried along. For example, if wool is used for the knitting, dust particles clinging to the wool, salt crystals stemming from the washing of the wool, sand or short filaments can be deposited on the closing element. As a result of the back-and-forth movement of the closing element, these particles can reach the closing element channel and lead to difficulties. 
     A compound needle of this type with divided closing element is known from U.S. Pat. No. 1,673,634. The closing element is composed of two connected closing element springs, which respectively push past the hook of the compound needle on the side and are spread apart in this way. 
     The arrangement of the compound needle disclosed in German Published Application 44 30 705, to which corresponds British Patent No. 2,292,953, is similar. The closing element in this case is also formed by two closing element springs, which are spread apart by moving past the hook on the side, thereby making it possible for dirt to be deposited between the closing element springs. 
     The same is true for the compound needle according to European Patent 08 75 614 to which corresponds U.S. Pat. No. 5,937,673. The compound needle comprises a needle member with needle channel, inside of which a closing element is guided. The closing element consists of a closing element base member that holds two closing element springs, which are designed to be symmetrical relative to each other. The needle hook periodically spreads apart the closing element springs during the operation, thereby allowing dirt and fiber residues to reach the gap defined between the closing element springs. 
     German Unexamined Patent Application 21 46 981 furthermore discloses a needle base member for a compound needle, which has a closing element channel with rear openings. The two walls on the side of the closing element channel are formed continuously, without openings, and between them limit the closing element channel. The closing element guided therein has elongated holes through which guide pins extend. The guide pins are respectively anchored in the side walls of the closing element. The closing element has a one-piece design. 
     German Published Patent Application 31 23 785 discloses another known compound needle. The known compound needle comprises a closing element divided into two closing element springs, which are designed to be symmetrical relative to each other. The closing element is arranged inside a compound needle closing element channel that is closed on three sides. An opening in the form of an elongated hole through which a guide pin extends is provided for guiding the closing element. 
     The problem with this as well as most of the previously mentioned compound needles is that dirt can reach the area between the two closing element springs. If that case occurs, it can lead to a gradual spreading apart of the closing element springs inside the closing element channel, so that with increasing amounts of dirt, the closing element can only be moved with difficulty inside the channel. In turn, this leads to increased friction and wear. In the extreme case where the closing element is extremely hard to move or is wedged inside the channel, the loop formation, the loop transfer and the loop knockover are obstructed. Given another extreme case, the closing elements can no longer be moved inside the closing element channel of the needle member, so that a butt break occurs. 
     SUMMARY OF THE INVENTION 
     Based on this assumption, it is the object of the invention to create a compound needle with little tendency to accumulate dirt. 
     This object is solved alternately with the compound needle according to claim  1  or the compound needle according to claim  2 . 
     Both solutions have in common that the divided closing element is not as likely to become wedged in as a result of stress caused by dirt. The closing element channel contains at least one area in which fiber residues can accumulate without causing the closing element springs to spread apart. According to claim  1 , the closing element springs are designed to be asymmetrical relative to each other. It means that they can overlap only partially in the closing element channel and thus do not fill out parts of the channel, which by itself creates additional buffer space in the closing element channel for holding foreign matter. Thus, a wedging in of the closing element is less likely and does not occur as quickly. In addition, the closing element channel is advantageously open on the side, meaning at least one of the channel sidewalls is provided with an opening or clearance. Alternatively or in addition, one or more openings can be provided in the bottom of the closing element channel. The opening on the side can be formed as a cutout in the closing element channel wall. Owing to the relative movement between closing element and needle base member, deposits that can reach the closing element channel wall because of the asymmetry of the two closing element springs can be moved through these openings or clearances into the needle channel. They are removed from the needle channel as a result of the relative movement between the compound needle and the needle channel. 
     The compound needle according to claim  2  is also based on this principle. Openings in the closing element springs initially permit deposits that have accumulated between the closing element springs to move from the gap formed between the closing element springs to the closing element channel walls and through the openings in these walls to the outside. 
     By preventing deposits that have accumulated between the closing element springs from forcedly spreading apart the closing element springs and wedge them against the closing element channel walls, the easy movement of the compound needle is maintained continuously, even if yarns with relatively high dirt loads must be processed. The compound needle according to the invention thus proves to have little tendency to accumulate dirt. 
     It is advantageous if the compound needles contain openings, which are arranged at different locations on the two closing element springs. The openings simultaneously create areas for holding and moving through the dirt that has entered the closing element channel, thus preventing dirt from being wedged between the closing element springs. In part, this also applies if the openings are arranged such that they overlap in some areas. The overlapping of the openings minimizes regions between the closing element springs, in which dirt could settle and spread apart the closing element springs. 
     One advantageous embodiment of the compound needle comprises a multi-part closing element, composed of a closing element member and closing element springs. These parts (closing element springs and closing element base member) can be rigidly connected or such that they can be detached. The closing element springs comprise web areas and web sections that extend in longitudinal direction of the channel, are displaced relative to each other and preferably do not overlap. With these, the above-mentioned advantages are realized to a particular degree. The web areas and web sections preferably extend through the closing element channel and are guided on the side by the channel sidewalls. The web sections change to guide sections for a guidance parallel to the closing element walls. These guide sections are preferably displaced relative to each other in longitudinal direction to prevent dirt from accumulating between the guide sections. 
     In addition, the closing element springs can also be designed asymmetrical between the guide sections and a respective loop-support section, which also leads to a reduced tendency for accumulating dirt and being wedged in. The closing element springs thus for the most part are not designed to overlap. 
     It is advantageous if the asymmetrically designed sections of the closing element springs are primarily arranged in the closing element channel. This results in a good side guidance of the closing element springs, which permits a reliable operation of the compound needle even at a high operating speed. 
     Further details of advantageous embodiments of the invention follow from the drawing, the description or the dependent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention are illustrated in the drawings, which show in: 
     FIG. 1 A compound needle according to the invention in a perspective exploded view. 
     FIG.  2  and FIG. 3 A view from the side of the closing element springs  22 ,  23  of the compound needle  1  according to FIG.  1 . 
     FIG. 4 A view from the side of the closing element base member  21  of closing element springs  22 ,  23  of the compound needle  1  according to FIG.  1 . 
     FIG. 5 The compound needle according to FIG. 6, in a sectional view along the line VI—VI and at a different scale. 
     FIG. 6 A perspective view of the compound needle according to FIG. 1 with closing element. 
     FIG. 7 A view from the side of a closing element for a modified version of a compound needle. 
     FIGS. 8 and 9 A side view of the closing element springs belonging to the closing element according to FIG.  7 . 
     FIGS. 10 and 11 A schematic view from the side of the closing element springs of a compound needle in a modified design embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a compound needle  1  with a needle member  2 , a closing element  3  that consists of two closing element springs  22 ,  23  and a closing element member  21 . The needle member  2  is inserted into the needle channel of a knitting machine and is provided for this with an elongated needle shank  4  with a hook  5  on its free end. The needle shank  4  extends in a straight line in longitudinal direction away from the hook  5 . Directly following the hook  5  starts a slot-shaped closing element channel  7 , which is limited on both sides by two channel side walls  8 ,  9 . The channel sidewalls  8 ,  9  are flat, plate-shaped structures that project upward at a distance and parallel to each other from the needle base member  2 . Starting with a slot beginning  11 , they initially increase in height. In a first region  12  that follows this region with increasing height, the height of sidewalls  8 ,  9  remains approximately constant. Following a further increase in height, the side walls  8 ,  9  then continue in a region  14  with increased height. The closing element channel  7  therefore comprises two different guide sections, which are formed by regions  12 ,  14 . 
     Relative to the longitudinal direction of the needle base member  2  and starting with the hook  5 , the channel side walls  8 ,  9  are long enough so that they do not completely emerge from a needle channel during the operational use of the compound needle  1 . The compound needle  1  is thus provided with at least a portion of its guidance. 
     Following the region carrying the channel side walls  8 ,  9 , the needle base member  2  is provided with an elongated opening  15 , which is limited in longitudinal direction on one side by the channel side walls  8 ,  9  and on an other side by a projection  16 . The opening  15  forms a region where the closing element channel  7  is open. However, it is also possible to provide openings on the side or in the bottom in place of the opening  15 . 
     The closing element  3  has a closing element member  21  (FIG. 4) and two closing element springs  22 ,  23  which are held against the closing element member  21 . The closing element member essentially consists of an elongated member with rectangular cross section on which one butt or several butts  24  are formed. These project at a right angle away from the closing element member  21  and function to drive the same. During the operation, they engage in the cam channel of a cam and are moved by this cam relative to the needle base member  2 . In its frontal region, the closing element member  21  has a receiving area  82  with which the closing element springs  22 ,  23  are connected. The closing element member  21  has a planar surface  84  on its side facing the needle member  2 . The thickness of the closing element base member  21  is approximately the same as that of the needle base member  2 . 
     The closing element  3  can be produced as one piece, consisting of the closing element member  21  and the two closing element springs  22 ,  23 , wherein these can be connected detachably or non-detachably with the closing element member  21 . They operate as one part. 
     FIGS. 2 and 3 show separate illustrations of the closing element springs  22 ,  23 . The closing element spring  22  essentially has an elongated member with rectangular cross section. Starting with the spring end region  81 , a web area  34  extends all the way to a guide section  35 . The guide section is arranged so as to maintain a clear distance to the bottom of the closing element channel  7  if the closing element spring  22  is inserted into or attached to the needle base member  2 . In other words, the closing element spring  22  contains a clearance or opening  34   a  in the web area  34 . 
     The web section  34  is followed by a guide section  35  of approximately the same height as the closing element channel  7 , which in special cases can even projects over this channel. The guide section  35  is provided with a lower contact surface  37 , which fits flush against the level bottom of the closing element channel  7  during the operation and thus also marks its height in FIG.  3 . 
     The guide section  35  is limited by a step  38  on the side facing the hook  5  or the loop-holding nose  33 , which step is at a right angle to the contact surface  37  where it changes to a narrow web section  39 . The web section  39  carries a plate-shaped, larger section  41 , which secures a loop-support shoulder  42  on the side facing the loop-holding nose  33 . 
     Relative to the closing element spring  22 , the closing element spring  23 , shown in FIG. 2, is asymmetrical in some sections. Both closing element springs  22 ,  23  are not mirror-symmetrical with respect to an imaginary plane between the two. A web area  47  that extends from the end region  81  of closing element spring  23  to a guide section  48  changes into this guide section via a steep step  49 . The closing element spring  23  is provided starting from the top with an opening  47   a , which advantageously overlaps on the side with the web area  34  of closing element spring  22 . Both openings  34   a ,  47   a  can be large enough to overlap in part on their broad sides. A contact surface  52  is formed on the closing element spring  23 , on the side opposite the opening  47   a . This lower contact surface  52  fits flush against the bottom of closing element channel  7 . 
     The guide section  48  of closing element spring  23  is offset against the guide section  35  of closing element spring  22  in longitudinal direction, in such a way that the steps  38 ,  49  are arranged at a distance to each other. In some application cases, the closing element springs  22 ,  23  are embodied such that the two steps  38 ,  49  overlap or are aligned with each other. The web areas  34 ,  47  are for the most part arranged such that they do not overlap which follows in particular from FIGS. 1 and 5. The guide section  48  of closing element spring  23  changes without interruption via a web section  53  or an opening (not shown here) to a plate-shaped section  54 . This section is designed to be mirror-symmetrical to section  41  of the closing element spring  22  and secures a loop-support shoulder  55 . 
     FIG. 6 contains details of the design of compound needle  1  and, in particular, of the closing element springs  22  and  23 . In the assembled state, the holding area  82  of closing element member  21  engages in the opening  15  of needle member  2 . The closing element springs  22 ,  23  freely extend through the closing element channel  7 , wherein the web areas  34 ,  47  do not overlap essentially, as follows from FIGS. 5 and 6. As shown in FIG. 5, the lower edge of the web area  34  can be arranged approximately at the same level as the upper edge of the web area  47 . However, in many cases it may be advantageous to leave a space, so that the lower edge of the web area  34  is arranged clearly above the upper edge of the web area  47  and the openings  34   a ,  47   a  overlap. A gap S then forms, which is inclined toward the channel side wall  8 ,  9 . 
     It may additionally be advantageous if the web area  47  does not fit over its complete length against the bottom of closing element channel  7 . 
     The steps  38 ,  49  of guide sections  35 ,  48  are at a distance to each other in longitudinal direction, so that these do not overlap. The closing element channel  7  extends far in the direction toward hook  5 , as illustrated clearly in FIGS. 1 and 6. The start of slot  11  is therefore arranged directly adjacent to the hook  5 . The frontal region  12  of closing element channel  7  provides guidance for the web sections  39 ,  53  until very close to the hook  5 . 
     The compound needle  1  described so far functions as follows: 
     During the operation, the closing element  3  performs a back-and-forth movement relative to the needle base member  2 . In a pulled-back position, the closing element springs  22 ,  23  are pulled back almost completely into the closing element channel  7 . The receiving area  82  of closing element member  21  clears a frontal portion of opening  15 , thereby freeing a large-area passage between closing element channel  7 , past the closing element channel side walls  8 ,  9 , to the needle channel sides. 
     If the closing element  3  is then displaced against the needle member  2 , the hook  5  enters the gap between the loop-holding noses and somewhat spreads apart the closing element springs  22 ,  23 . In the process, filaments, dust or other deposits can also reach the area between the closing element springs  22 ,  23 . If the closing element  3  is subsequently returned to the pulled-back position, the closing element springs  22 ,  23  are not longer spread apart and are pulled back into the closing element channel  7  together with the dirt that has entered the gap. However, filaments or other dirt carried along does not lead to the closing element springs  22 ,  23  being wedged into the closing element channel  7 , not even if new deposits constantly enter the gap during many successive lifts. The web areas  34 ,  47  dot not press against each other, but past each other. The compound needle is therefore for the most part insensitive to dirt accumulation. Any dirt carried along is furthermore removed through the relative movement between the web areas  34 ,  47  and the channel side walls  8 ,  9  to the opening  15  and through this opening into the needle channel. 
     FIG. 7 shows a modified version of a closing element  3 . It contains a closing element member  21 ′ and two closing element springs  22 ′,  23 ′ that are held against the closing element member  21 ′. The closing element  3 ′ can also be designed as one piece. The closing element member  21 ′ is essentially an elongated web with rectangular cross section and one or several formed-on butts  24 . These butts project at right angles away from the closing element member  21 ′ and function as its drive. During the operation, they engage in the cam channel of a cam and are moved by it relative to the needle base member  2 . 
     The frontal region of closing element member  21 ′ contains a guide section  25  on which a planar surface  26  is formed on the side facing the needle member  2 . The guide section has the same thickness as the section of closing element member  21 ′ that extends to the butts  24 ′ and coincides approximately with the thickness of needle base member  2 . 
     The guide section  25  is followed by a holding section  27 , which projects away from the closing element member  21 ′ and into the opening  15 . The height of holding section  27  here coincides with the depth of the opening  15 . However, it is shorter in longitudinal direction than the opening  15 , so that a considerable longitudinal movement of the closing element  3 ′ is possible. 
     The holding section  27  of closing element  3 ′ furthermore contains a flat, wide groove  28  that is open on the side and is designed to accommodate holding ends  29  of the closing element springs  22 ′,  23 ′, which are wedged into a window-like opening  31  of the closing element member  21 ′. 
     Starting with the holding ends  29 , the closing element springs  22 ′,  23 ′ extend past a window-like opening  31  or a fastening location. They respectively engage with one fastening flange  32  in the window-like opening  31  and can be wedged into this opening. A loop-holding nose  33  forms the outermost end on the opposite side. 
     The closing element springs  22 ′,  23 ′ are shown separately in FIGS. 8 and 9. The closing element spring  22 ′ is essentially an elongated member with rectangular cross section. Starting with its holding region  29 , a web area  34 ′ extends to a guide section  35 ′. Following the fastening flange  32 , the closing element spring  22 ′ changes to a web area  34 ′ that is not as high as the side walls  8 ,  9  of the needle base member. The web area is arranged so as to maintain a clear distance to the bottom of the closing element channel  7  if the closing element  3 ′ is inserted into or fitted onto the needle base member  2 . In other words, the closing element spring  22 ′ has a clearance or opening  34   a ′ in the web area  34 ′. 
     Connecting to the web area  34 ′ is a guide section  35 ′, which has approximately the same height as the closing element channel  7  and exceeds this height in special applications. At the upper end, it is provided with a contact surface  36  for the planar surface  26  of guide section  25  of closing element member  21 ′. On the opposite side, the guide section  35 ′ is provided with a lower contact surface  37 ′, which fits flush against the level bottom of the closing element channel  7  during the operation and thus also marks its height in FIG.  8 . 
     The guide section  35 ′ is limited by a step  38 ′ on the side facing the hook  5  or the loop-holding nose  33 , which step is aligned at a right angle to the contact surface  37 ′ where it then changes to a narrow web section  39 ′. This web section  39 ′ carries a plate-shaped, larger section  41 ′ that secures a loop-support shoulder  42 ′ on the side facing the loop-holding nose  33 . 
     The closing element spring  23 ′ shown in FIG. 9 has an asymmetrical design in some sections, relative to the closing element spring  22 ′. Both closing element springs  22 ′,  23 ′ are not mirror-symmetrical with respect to an imaginary plane between them. With the closing element spring  23 ′, a web area  47 ′ extends from the holding end  29  to a guide section  48 ′ into which it changes via a steep step  49 ′. The closing element spring  23 ′ is provided from the top with an opening  47   a ′, which preferably overlaps on the side with the web area  34 ′ of closing element spring  22 ′. The dimensions of both openings  34   a ′ and  47   a ′ can be such that they partially overlap on their broad sides. The guide section  48 ′ has a contact surface  51  on the top, which fits flush against the planar surface  26  of closing element member  21 ′ during the operation. On the lower side opposite the contact surface  51 , a contact surface  52 ′ is formed on the closing element spring  23 ′, which extends over a large portion of the web area  47 ′. This lower contact surface  52 ′ fits flush against the bottom of contact element channel  7 . 
     Stated generally, and with particular reference to FIGS. 5,  8  and  9 , the two closing element springs  22 ′,  23 ′ have mutually longitudinally aligned length portions of unlike configuration. Thus, the web portion  34 ′ of the closing element spring  22 ′ is in longitudinal alignment with the web portion  47 ′ of the closing element spring  23 ′, but the web portions  34 ′ and  47 ′ are differently shaped. Similar considerations apply to the mutually longitudinally aligned web portions  39 ′ and  53 ′ of the respective closing element springs  22 ′ and  23 ′. As a result, such longitudinally aligned length portions have parts that are offset with respect to one another as viewed perpendicularly to the longitudinal direction of the closing element springs  22 ′,  23 ′. In particular, as a comparison of FIGS. 8 and 9 shows, and as it may also be seen in the sectional FIG. 5 for the web portions  34  and  47 , the web portions  34 ′ and  47 ′ extend in their entirety at different height positions and are thus entirely non-overlapping. Such an offset arrangement of length portions of the closing element springs provides space for lint or dirt to avoid an increase in friction during operation of the needle. 
     In addition, it can be advantageous if the web area  47 ′ does not fit with its entire length flush against the bottom of closing element channel  7 . For this, the web area  47 ′ has a step  58  that is shown in FIG.  9 . 
     The guide section  48 ′ of closing element spring  23 ′ is offset against the guide section  35 ′ of closing element spring  22 ′ in longitudinal direction, such that the steps  38 ′,  49 ′ are located approximately at the same level or are arranged at a slight longitudinal distance to each other. Conceivable are furthermore applications where the closing element springs  22 ′,  23 ′ are realized such that the two steps  38 ′,  49 ′ overlap or are aligned with each other. The web areas  34 ′,  47 ′ are also arranged such that they do not overlap for the most part. The closing element spring  23 ′ has a web section  52 ′ that follows the guide section  48 ′ and changes over to a plate-shaped section  54 ′. This latter section is mirror-symmetrical to the section  41 ′ of closing element spring  22 ′ and secures a loop support shoulder  55 ′. 
     A modified embodiment of the compound needle  1  is obtained with the closing element springs  22 ″,  23 ″ in FIGS. 10 and 11. The closing element springs  22 ″,  23 ″ are designed to be mirror-symmetrical, wherein they have elongated hole-shaped openings  61 ,  62  in their web areas or web sections  34 ″,  39 ″ or  47 ″,  53 .″ The openings can serves as spaces where fibers or other deposits collect and through which they can be transferred, at least at times, to the region of opening  15  in the needle member  2 , so that existing deposits can then be transferred to the needle channel. However, in some instances the sensitivity to being wedged in of a compound needle with closing element springs  22 ″,  23 ″ is somewhat higher than that of a compound needle with closing element springs  22 ,  23  or  22 ′,  23 ′ according to FIGS. 2,  3  or  8  and  9 . Otherwise, the closing element springs  22 ″,  23 ″ coincide for the most part with the closing element springs  23 ′,  23 ′, so that we can point to the corresponding description based on the same reference numbers. The closing element springs  22 ″,  23 ″ can also have an asymmetrical design in that the openings  61 ,  62  are displaced against each other. 
     A compound needle  1  comprises a closing element  3  with two closing element springs  22 ,  23 , which are designed asymmetrical to each other, or at least are provided with clearances or openings  34   a ,  47   a . These openings are made to coincide during the compound needle  1  operation with a corresponding opening  15  or other openings in the base member  2  of compound needle  1 , so that deposits can be removed to the needle channel. An asymmetrical design of the closing element springs  22 ,  23  prevents the closing element  3  from being wedged into the closing element channel  7 , even if only an incomplete removal of the deposits occurs. The wear of the compound needle  1  is greatly reduced by this, thereby increasing the operational safety. 
     It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.