Abstract:
A method and apparatus is disclosed for manufacturing sinuous springs wherein each spring comprises a discrete length of sinuous spring wire having parallel straight bar segments interconnected at their opposite ends by oppositely directed curved connecting segments. This apparatus is operable to adjust the length of the sinuous spring wires exiting the machine without turning off or stopping the machine. An operator need only rotate a handle outside a housing of the machine to increase or decrease the length of the sinuous spring wires exiting the machine.

Description:
FIELD OF THE INVENTION  
       [0001]    This invention relates generally to sinuous wire springs and, more particularly, to a method and apparatus for producing sinuous wire springs. 
       BACKGROUND OF THE INVENTION  
       [0002]    Many furniture products, including such products as chairs, sofas and automobile seats utilize sinuous wire spring elements as to create resilient surfaces, such as seats and backrests, in an item of furniture. Such resilient spring elements are disclosed, for example, in U.S. Pat. No. 6,263,573. Each resilient sinuous spring element has a plurality of straight bar portions joined by a plurality of connecting or curved or radiused portions. Generally, these sinuous spring elements are manufactured on a machine which produces a quantity of identical sinuous springs, each sinuous spring having the same number of straight bar portions and the same radius in its curved portions. Therefore, each resilient sinuous spring element has the same length. The machine had to be stopped and adjusted to manufacture sinuous spring elements of different lengths. Prior to the present invention, in order to adjust the length of the resultant sinuous spring element, one had to stop the operation of the machine and make the necessary adjustments to the machine. Upon restarting the machine, a different size resilient sinuous spring element would be produced. Each time a different length of resilient sinuous spring element was desired, the operator had to stop the machine, adjust the machine and then restart the machine. Each time the operator stopped the machine, the machine was not producing resilient sinuous spring elements. This reduced the output of the machine and required skilled operators to properly adjust the machine. 
         [0003]    Therefore, it is one objective to the present invention to provide a machine for manufacturing sinuous spring elements which does not have to be stopped or turned off in order to change the length of the resilient sinuous spring element produced by the machine. 
         [0004]    It is another objective of the present invention to provide an apparatus for use on a machine used to make sinuous spring elements which enables the machine to produce sinuous spring elements of different lengths without turning off the machine. 
         [0005]    It is another objective of the present invention to maintain a desired length of sinuous spring despite changes in machine speed and/or changes to the wire being introduced into the machine. 
       SUMMARY OF THE INVENTION  
       [0006]    The apparatus or machine of this invention which accomplishes these objectives and one aspect of the invention of this application comprises a machine for manufacturing a plurality of sinuous springs from a supply of wire. The machine comprises a forming apparatus for forming a continuous length of sinuous spring wire having parallel bar segments interconnected at their opposite ends by oppositely directed connecting segments. The forming apparatus includes a shuttle, an oscillator and an overbend tool adjustable during operation of the machine via an adjustment apparatus. 
         [0007]    The adjustment apparatus functions to adjust or change the position of the overbend tool via a rotation of a rotatable handle, the handle being outside the housing of the forming apparatus. The adjustment apparatus comprises an adjustment rod having a first end and a second end. The handle is connected to the first end of the adjustment rod for adjusting the length of the adjustment rod. The adjustment apparatus further comprises an end piece connected to the second end of the adjustment rod. The end piece is operatively coupled to an adjustment link at one end of the adjustment link; the opposite end of the adjustment link being operatively coupled to a crank lever which oscillates about an axis defined by a bearing pin. The crank lever is driven by a crank disc via a push rod assembly connected at one end to the crank disc and at the other end to one end of the crank lever. The opposite end of the crank lever is operatively coupled to a slide block which reciprocates in a linear manner. 
         [0008]    The slide block has a pair of cam blocks and a pair of guide pins attached thereto. The cam blocks have slots therein for guiding an overbend tool assembly, the guide pins being retained in the overbend tool assembly for further guiding said overbend tool assembly. The adjustment apparatus further comprises a cover with a slot therein thorough which a portion of the overbend tool assembly passes to provide a stop for the wire. The adjustment apparatus further comprises a guide cover and a pair of clamp assemblies for securing the guide cover in place. During operation, the sinuous wire passes under the guide cover and over the cover. The machine comprises lubrication means to keep the machine components lubricated to help the continuous length of sinuous spring wire move through the forming apparatus smoothly and withing binding until it passes to an accumulator. 
         [0009]    The machine further comprises an accumulator downstream of the forming apparatus and a punch press for cutting the continuous length of sinuous wire into sinuous springs of discrete lengths. The punch press is downstream of the accumulator. 
         [0010]    According to another aspect of this invention, a method of manufacturing sinuous springs is provided. Each sinuous spring comprises a discrete strip of sinuous spring wire having parallel bar segments interconnected at their opposite ends by oppositely directed connecting segments. The method comprises first introducing a continuous supply of wire into a machine. The method further comprises forming a continuous length of sinuous spring wire having parallel bar segments interconnected at their opposite ends by oppositely directed connecting segments using a forming apparatus. The forming apparatus includes a shuttle, an oscillator and an overbend tool adjustable during operation of the machine via an adjustment apparatus to change the position of the parallel bar segments relative to the connecting segments in the resulting continuous length of sinuous spring wire which exits the forming apparatus and passes through the accumulator and onto the punch press for cutting the continuous strip of sinuous wire into strips of discrete lengths. 
         [0011]    Another way to describe this method is as follows: a method of manufacturing sinuous springs, each sinuous spring comprising a discrete strip of sinuous spring wire having parallel bar segments interconnected at their opposite ends by oppositely directed connecting segments. The method comprises first providing a machine for manufacturing sinuous springs of the same length and then adding an adjustment apparatus to the machine so an operator may adjust the length of the sinuous springs by turning a handle. The adjustment apparatus changes the position of an overbend tool adjustable during operation of the machine to change the position of the parallel bar segments relative to the connecting segments. Using this method to retrofit an existing machine enables an operator to change the length of the sinuous springs exiting the punch press without stopping or interrupting the operation of the machine. Allowing the machine to operate continuously improves the productivity and efficiency of the machine while reducing the need for a skilled operator to adjust the machine. 
         [0012]    These and other objects and advantages of this invention will become more readily apparent from the following description of the drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS  
         [0013]      FIG. 1  is a perspective view of a machine for practicing the inventive method of this invention; 
           [0014]      FIG. 2  is an enlarged perspective view of the adjustment apparatus comprising part of the machine of  FIG. 1 ; 
           [0015]      FIG. 3  is a top plan view of a sinuous spring of a first length produced on the machine of  FIG. 1 ; 
           [0016]      FIG. 4  is a top plan view of a sinuous spring of a second length greater than the first length produced on the machine of  FIG. 1 ; 
           [0017]      FIG. 5  is a disassembled view of the adjustment apparatus of  FIG. 2 ; 
           [0018]      FIG. 6  is a diagrammatic perspective view of the adjustment apparatus of  FIG. 2 ; 
           [0019]      FIG. 7A  is a side elevational view of an inside surface of the rear cam block of  FIG. 5 ; 
           [0020]      FIG. 7B  is a side elevational view of an outside surface of the rear cam block of  FIG. 5 ; 
           [0021]      FIG. 8A  is a side elevational view of an outside surface of the front cam block of  FIG. 5 ; 
           [0022]      FIG. 8B  is a side elevational view of an inside surface of the front cam block of  FIG. 5 ; 
           [0023]      FIG. 9A  is a top perspective view of the slide block of  FIG. 5 ; 
           [0024]      FIG. 9B  is a bottom perspective view of the slide block of  FIG. 5 ; 
           [0025]      FIG. 10A  is a top view of the oscillator moving in a counterclockwise direction to begin forming a continuous length of sinuous wire; 
           [0026]    FIG.  10 AA is a side elevational view of a portion of the adjustment apparatus showing the position of the overbend tool while the oscillator is in the position shown in  FIG. 10A ; 
           [0027]      FIG. 10B  is a top view of the oscillator moving in a counterclockwise direction while continuing to form a continuous length of sinuous wire; 
           [0028]    FIG.  10 BB is a side elevational view of a portion of the adjustment apparatus showing the position of the overbend tool while the oscillator is in the position shown in  FIG. 10B ; 
           [0029]      FIG. 10C  is a top view of the oscillator in a stopped position; 
           [0030]    FIG.  10 CC is a side elevational view of a portion of the adjustment apparatus showing the position of the overbend tool while the oscillator is in the position shown in  FIG. 10C ; 
           [0031]      FIG. 10D  is a top view of the oscillator moving in a clockwise direction to begin forming a continuous length of sinuous wire; 
           [0032]    FIG.  10 DD is a side elevational view of a portion of the adjustment apparatus showing the position of the overbend tool while the oscillator is in the position shown in  FIG. 10D ; 
           [0033]      FIG. 10E  is a top view of the oscillator moving in a clockwise direction to begin forming a continuous length of sinuous wire; 
           [0034]    FIG.  10 EE is a side elevational view of a portion of the adjustment apparatus showing the position of the overbend tool while the oscillator is in the position shown in  FIG. 10E ; 
           [0035]      FIG. 10F  is a top view of the oscillator moving in a clockwise direction to begin forming a continuous length of sinuous wire; and 
           [0036]    FIG.  10 FF is a side elevational view of a portion of the adjustment apparatus showing the position of the overbend tool while the oscillator is in the position shown in  FIG. 10F . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0037]    Referring to the figures, and particularly, to  FIG. 1 , there is illustrated a machine  10  for manufacturing a plurality of sinuous springs  12 . The machine  10  has three principal components: a forming apparatus  14 , an accumulator  16  downstream of the forming apparatus  14  and a punch press  18  downstream of the accumulator  16  (the flow of wire is generally indicated by the arrow  20 ). 
         [0038]    The forming apparatus  14  enables sinuous springs  12 a,  12 b to exit the downstream end of the machine  10  of different lengths without turning off or shutting down the machine  10  to make manual adjustments to it. Instead, an adjustment apparatus  32 , shown in an assembled condition in  FIG. 2 , and disassembled in  FIG. 5 , has been incorporated into the machine  10 . More particularly, the adjustment apparatus  32  has been incorporated into the forming apparatus  14  of the machine  10  to enable sinuous springs of different lengths to be produced on the machine  10  without stopping the machine  10 . As best shown in FIGS.  10 A- 10 FF, forming apparatus  14  includes a shuttle  15  and an oscillator  17  downstream of the shuttle  15 . The oscillator rotates clockwise and counterclockwise a full 360 degrees and includes two pins  19   a  and  19   b , pin  19   a  being illustrated with a plus symbol on it and pin  19   b  being illustrated with a minus symbol on it for purposes of clarification. See FIGS.  10 A- 10 FF. 
         [0039]    As shown in  FIGS. 3 and 4 , the machine  10  of the present invention produces sinuous springs  12   a  and  12   b  along with sinuous springs of different lengths.  FIG. 3  shows a sinuous spring  12   a  having seven straight parallel bar segments  22   a  joined at their ends by oppositely directed curved or arcuate connecting segments  24   a . The sinuous spring  12   a  has at each end a tail portion  26   a . The sinuous spring  12   a  has a length L 1  which may be increased by a length L 3  (the difference between L 2  and L 1 ) simply by rotating a handle  28  located outside a housing  30  of the forming apparatus  14  from one extreme to another.  FIG. 1  shows the housing  30  partially broken away so that one may see the adjustment apparatus  32  of the present invention. 
         [0040]      FIG. 4  shows a sinuous spring  12   b  which may be produced on machine  10  without having to stop or interrupt operation of the machine. Sinuous spring  12   b , like sinuous spring  12   a , has seven straight parallel bar segments  22   b  joined at their ends by oppositely directed curved or arcuate connecting segments  24   b . The sinuous spring  12   b  has at each end a tail portion  26   b . The sinuous spring  12   b  has a length L 2  greater than the length L 1  of sinuous spring  12   a  by a distance L 3 . The machine  10  may produce sinuous springs having any desired number of straight bar segments and corresponding connecting segments. 
         [0041]    A servo drive (not shown) drives a feed wheel (not shown) and counts the number of straight parallel bar segments prior to activation of the punch press  18 . The accumulator allows wire to continue flowing through the forming apparatus  14  while the flow of sinuous wire is momentarily stopped to allow the punch press  18  to sever the sinuous wire at the desired location. The servo drive momentarily stops the flow of sinuous wire to allow the punch press to activate. 
         [0042]      FIG. 2  illustrates the adjustment apparatus  32  for use in the forming apparatus  14 . The adjustment apparatus  32  is used to change the position of the overbend tool  34  as a front portion or stop  142  extends upwardly through a slot  40  in a cover plate  39  and through a slot  2  in a guide cover  42 . 
         [0043]      FIG. 5  illustrates a disassembled view of the adjustment apparatus  32 . The adjustment apparatus  32  comprises an adjustment rod  36  having a first end  37  to which a three-pronged handle  28  is attached outside of the housing  30 . The handle  28  may be locked in a fixed position by a locking mechanism  35  comprising a cover plate  154 , a hub  41 , a locking handle  43  and a lock block  45 . 
         [0044]    An end piece  44  is attached to the opposite end  38  of the adjustment rod  36 , the end piece  44  having a centrally located hole  46  therethrough. A threaded fastener  48  ends through the hole  46  in the end piece  44  and is threadably engaged inside a hole  50  at one end of an adjustment link  52 . The adjustment link  52  acts as a teeter totter and oscillates or pivots about a vertical axis A 1  defined by a pivot pin  54  which extends through bearings  56  located inside a pivot mount  58 . The other end of the adjustment link  52  has recesses  60  into which fit bearings  62 . A bearing pin  64  extends through bearings  62  and defines a vertical axis A 2  which is located at the center of a crank lever  66 . Thus, one end of the adjustment link  52  is joined by bearing pin  64  to the center of the crank lever  66 , which acts as a second teeter totter device and pivots about the second axis A 2  defined by bearing pin  64 . One end of the crank lever  66  is secured to a push rod assembly  68  comprising a push rod  70  and two opposed push rod ends  72 ,  74 . Push rod end  74  is secured to a crank disk  76  with fasteners  75  and may be manually adjusted, if desired. The crank disk  76  has a plurality of openings  73  into which fasteners  75  fit. 
         [0045]    By changing the position of the push rod assembly  68  relative to the crank disk  76 , one may adjust the extreme positions of the overbend tool  34  and more specifically, the position of the front stop  142  of the overbend tool  34 . The crank disk  76  has a counterweight  78  attached thereto and is mounted in an upper bearing mount  80  located above an oil pan  82  and driven by a drive shaft  84  which passes through an opening  86  in the oil pan  82 . The drive shaft  84  is operably coupled to a timing pulley  88  using a keyed locking mechanism. A bearing mount  90  is below the timing pulley  86  and houses bearing  92 . A timing belt  94  passes around the timing pulley  86  and around a drive pulley  96 . An idler assembly  98  is located inside the timing belt  94 . Rotation of the drive pulley  96  rotates the timing belt  94  which rotates the drive shaft  84  driven by the timing pulley  88 . Rotation of the drive shaft  84  rotates the crank disc  76  inside which resides bushing  100 . Rotation of the crank disk  76  moves the push rod assembly  68 . More specifically, push rod end  74  is secured to the crank disk  76  while push rod end  72  is secured to one end of the crank lever  66 . 
         [0046]    The opposite end of the crank lever  66  has an opening  102  therein in which there is secured a cam follower  104 . The cam follower  104  rides in a guide  106  in the underside of a slide block  108  which moves in a linear fashion as indicated by arrow  109 . Front and rear cam blocks  110 ,  112  are mounted to the slide block  108  as shown in  FIG. 5 .  FIGS. 7A and 7B  show inner and outer surfaces  114 ,  116  respectively, of the rear cam block  112  along with an opening  118  through the rear cam block  112 .  FIGS. 8A and 8B  show inner and outer surfaces  115 ,  117  respectively, of the front cam block  110  along with an opening  119  through the front cam block  110 . 
         [0047]    An overbend tool assembly  120  comprising an overbend tool  34 , a front cam pin  124  secured to overbend tool  34  with a fastener  125  and a rear cam pin  126  secured to overbend tool  34  with a fastener  127  moves in and out and up and down in a manner shown in FIGS.  10 A- 10 FF. The front cam pin  124  moves in a groove  130  extending inwardly from the inside surface  117  of the front cam block  110 . The rear cam pin  126  moves in a groove  132  extending inwardly from the inside surface  114  of the rear cam block  112 . Another groove  134  is located along the inside surface  114  of the rear cam block  112  to allow the fastener  127  to travel with the overbend tool  34 . Similarly, another groove  136  is located along the inside surface  115  of the front cam block  110  to allow the fastener  125  to travel with the overbend tool  34 . The overbend tool has a pair of pins  122  extending downwardly from the overbend tool  34 . These pins  122  fit into two of the holes  123  extending upwardly from a lower surface of the slide block  108 , as shown in  FIGS. 9A and 9B . 
         [0048]    Referring to  FIG. 5 , a debris guard  138  is located at the front of the slide block  108  and a push block  140  is secured to the rear of the slide block  108 . The overbend tool  34  has a front stop  142  against which the wire abuts when the machine is operating. The adjustment apparatus  32  further comprises a cover plate  39  having a slot  40  therein. The cover plate  39  is located above the overbend tool  34 , the stop  142  of the overbend tool  34  extending through the slot  40  in the cover plate  39 . The top of the cover plate  39  is lubricated via fluid flowing through holes  144  in the cover plate  39 . A pair of oil rail inserts  146  are secured to the cover plate  39 . As shown in  FIG. 6 , oil flows from an oil source  148 , through hoses or lines  150  and through the oil rail inserts  146  to lubricate the upper surface of cover plate  39 . 
         [0049]    As shown in  FIG. 2 , the continuous length of sinuous wire  5  extends over the top of the cover plate  39  and underneath a guide cover  42  which is clamped in place using a pair of clamp assemblies  150 . The continuous length of sinuous wire  5  passes below the guide cover  42  and above the cover plate  39  as it is flowing downstream into the accumulator  16  and then on to the punch press  18 . 
         [0050]    FIGS.  10 A and  10 AA show the position of the shuttle  15 , oscillator  17  and overbend tool  34  in an initial position while an initial portion of wire  6  drawn from a wire source  7  is being formed into a continuous length of sinuous wire  5 . The oscillator  17  has a cap  9  and a shaft  11 . The letter “D” in  FIG. 10A  indicates the lateral distance the overbend tool  32  changes due to the adjustment apparatus  32 . FIG.  10 AA shows the overbend tool  32  in a down position and at its furthest left or withdrawn position. The principal advantage of the present invention is that by rotating the wheel  28  outside housing  30  of the forming apparatus  14  of machine  10 , one may adjust the extreme positions of the overbend tool  34 , the stroke distance remaining the same but moving laterally to one side or the other. By rotating the wheel  28  of the adjustment apparatus  32  one may change the extreme withdrawn position (to the left in  FIG. 10A ) of the overbend tool  34  from the position shown in solid lines to the position shown in dashed lines. The letter “D” is shown in FIG.  10 AA to show this change in position. By changing the extreme positions of the overbend tool  34 , the operator may lengthen or shorten the length of the sinuous spring exiting the punch press (assuming two comparable sinuous springs having the same number of straight parallel bar segments and the same number of connecting segments of the same radius). This change in length is accomplished by changing the angle between the parallel bar segments and the connecting segments. 
         [0051]    The vertical distance traveled by the overbend tool  34  during a cycle or stroke does not change regardless of the position of the handle  28  of the adjustment apparatus  32  and regardless of the position of the end  74  of the push rod assembly  68  relative to the crank disc  76 . The horizontal distance traveled by the overbend tool  34  during a cycle or stroke does not change regardless of the position of the handle  28  of the adjustment apparatus  32 , but does change upon a change in position of the end  74  of the push rod assembly  68  relative to the crank disc  76 , i.e. changing the position of fasteners  75  in openings  73 . This lateral distance of the stroke may be changed by changing the position of the end  74  of the push rod assembly  68  relative to the crank disc  76 . This is accomplished by changing the openings  73  in crank disc  76  into which fasteners  75  engage and hold the end  74  of the push rod assembly  68  and crank disc  76 . The horizontal distance traveled by the overbend tool  34  during a cycle or stroke does not change regardless of the position of the handle  28  of the adjustment apparatus  32  but the extreme positions of a stroke or cycle do move left or right as shown in  FIGS. 10A ,  10 AA,  10 F and  10 FF. In other words, the front stop  142  of the overbend tool  34  may be moved to the left away from the axis of the oscillator, thereby changing the angle between the parallel bar segments and the connecting segments of the resulting sinuous springs. 
         [0052]    FIGS.  10 B and  10 BB show the position of the shuttle  15 , oscillator  17  and overbend tool  34  in another position. The oscillator  17  has changed positions relative to its position shown in FIG.  10 A and  10 AA. The letter “U” in  FIG. 10B  indicates that the overbend tool  34  is in an up position. FIG.  10 BB shows the overbend tool  34  at another position to the right of the position shown in FIG.  10 AA. 
         [0053]      FIGS. 10C ,  10 CC,  10 D,  10 DD,  10 E,  10 EE,  10 F and  10 FF show other positions of the oscillator  17  and overbend tool  34  during the process of making a continuous length of sinuous spring wire. FIGS.  10 F and  10 FF, like FIGS.  10 A and  10 AA, show the principal advantage of the present invention. By rotating the wheel  28  outside housing  30  of the forming apparatus  14  of machine  10 , one may adjust the extreme positions of the overbend tool  34 . By rotating the wheel  28  of the adjustment apparatus  32  one may change the extreme exposed position (to the right in  FIG. 10F ) of the overbend tool  34  from the position shown in solid lines to the position shown in dashed lines. The letter “D” is shown in FIG.  10 FF to show this change in position. By changing the extreme positions of the overbend tool  34 , the operator may lengthen or shorten the length of the sinuous spring exiting the punch press (assuming two comparable sinuous springs having the same number of straight parallel bar segments and the same number of connecting segments of the same radius). This change in length is accomplished by changing the angle between the parallel bar segments and the connecting segments. 
         [0054]    While I have described only one preferred embodiment of this invention, persons skilled in this art will appreciate changes and modifications which may be made without departing from the spirit of this invention.