Patent Publication Number: US-6910360-B2

Title: Multiple wire feed for spring coiling machine and method

Description:
FIELD OF THE INVENTION 
   This invention relates to spring coiling machines and, more particularly, to a multiple wire feed apparatus for a spring coiling machine. 
   BACKGROUND OF THE INVENTION 
   A continuing effort to more cost efficiently manufacture furniture of different kinds has led to continuous improvements in the production of spring coils. Further, there is a continuing effort to improve the quality and comfort of furniture in which spring coils are used, for example, seating cushions and mattresses. In particular, in order to support a human body in the proper posture when lying on a mattress, in many mattresses, it is desired to provide a mattress with spring coils at different locations having differing stiffness or spring constants to conform with the loading imposed by a human body. 
   In order to change the stiffness of a spring coil, a different diameter or gage wire is sometimes used to form the coil, for example, a thicker wire is used to make a stiffer coil and a thinner wire is used to make a less stiff coil. The tooling of known spring coiling machines is made to handle a specific wire diameter. Therefore, if it is desired to use a wire of a different diameter, the wire specific tooling of the spring coiling machine must be replaced with tooling made to handle wire of the different diameter. Obviously, the requirement of physically switching the tooling on a spring coiling machine so that it can work with a different size of wire is time consuming and expensive. Not only is there the added cost of skilled labor required to modify the spring coiling machine, but there is a significant cost in the production lost from the spring coiling machine while it is shut down for the tooling changeover. In addition, the further cost to manufacture and store different sets of wire specific tooling is also burdensome. 
   It is known to be able to automatically and continuously manufacture spring coils of different diameter and pitch from the same wire, thereby providing spring coils of differing stiffness or spring constants. However, the limitation of making spring coils from only a single wire severely limits the range of spring coil stiffness that can be provided. Further, the end product, for example, a mattress, is a fixed size and is normally designed to use a predetermined number of spring coils. Changing the diameter of selected spring coils to change the coil stiffness causes the number of spring coils used in the mattress to also change. Adding another variable, that is, the number of spring coils, substantially complicates the mattress design and manufacturing processes; and therefore, in the production of mattresses and other seating furniture, it is not practical to change spring coil stiffness by changing the spring coil diameter. 
   Consequently, there is a need for a spring coiling machine having a wire feed that permits coil springs to be automatically and continuously manufactured from different sizes of wire. 
   SUMMARY OF THE INVENTION 
   The present invention provides a simple and reliable apparatus for automatically and rapidly changing wires and tool settings to an input of a spring coiling machine. The apparatus of the present invention uses the same tooling on a spring coiling machine to make spring coils using different diameters of wires. Further, the apparatus of the present invention is able to automatically selectively feed wires of different diameters sizes to a spring coiling machine, thereby saving on the need for manual labor to change tooling. The apparatus of the present invention is especially useful in making spring coils for furniture, such as mattresses and seating furniture, in which spring coils of a common diameter but differing stiffnesses are often used. By providing for the automatic and continuous manufacture of constant diameter spring coils from wires of different sizes, the multiple wire feed apparatus permits such furniture to be made more quickly and at a substantially reduced cost. 
   According to the principles of the present invention and in accordance with the preferred embodiments, the invention provides an apparatus for making mattress and upholstery spring coils. The apparatus has a powered wire feeding device and a wire guide adapted to support first and second wires of different diameters. The wire guide is located on an input side of the wire feeding device and is movable to first and second positions to align the first and second wires, respectively, with the wire feeding device. A spring coiling machine is positioned adjacent an output side of the wire feeding device. When the wire guide is in the first position, the spring coiling machine receives the first wire of one diameter from the wire feeding device; and the spring coiling machine bends the first wire into a spring coil of a desired diameter and pitch and having a first stiffness. When the wire guide is in the second position, the spring coiling machine receives the second wire of another diameter from the wire feeding device; and the spring coiling machine bends the second wire into a spring coil of the desired diameter and pitch but having a second stiffness. 
   In another embodiment of the invention, a method is provided for making mattress and upholstery spring coils in which a plurality of wire paths are provided adjacent an inlet of a powered wire feeding device. The plurality of wire paths are moved to align one of the plurality of wire paths with an input side of the wire feeding device. The wire feeding device moves a first wire having a first diameter into a spring coiling machine, and the spring coiling machine is operated to make a first spring coil having a desired diameter and a first stiffness. The operation of the spring coiling machine and the wire feeding device is terminated, and the plurality of wire paths are moved to align another wire path with the wire feeding device. The wire feeding device moves a second wire having a second diameter into the spring coiling machine, and the spring coiling machine makes a second spring coil having the desired diameter and a second stiffness. 
   In one aspect of this invention, the spring coiling machine has a bending device; and after the spring coiling machine makes the first spring coil, the bending device is adjusted as a function of the diameter of the second wire. 
   These and other objects and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic, perspective view of a four-wire feed apparatus in accordance with the principles of the present invention. 
       FIG. 2  is perspective view of a two-wire feed portion of the four-wire feed apparatus of FIG.  1 . 
       FIG. 3  is a view showing, in elevation, wire straightening rollers on the multiple wire feed apparatus taken along line  2 — 2  of FIG.  1 . 
       FIG. 4  is a view showing, in partial elevation, feed and pressure rollers on the multiple wire feed apparatus taken along line  3 — 3  of FIG.  1 . 
       FIG. 5  is a schematic, partial cross-sectional view of the multiple wire feed apparatus of  FIG. 1  feeding a first wire. 
       FIG. 6  is a schematic, partial cross-sectional view of the multiple wire feed apparatus of  FIG. 1  feeding a second wire. 
       FIG. 7  is a schematic, partial cross-sectional view of the multiple wire feed apparatus of  FIG. 1  feeding a third wire. 
       FIG. 8  is a schematic, partial cross-sectional view of the multiple wire feed apparatus of  FIG. 1  feeding a fourth wire. 
       FIG. 9  is a schematic, perspective view of a spring coiling machine to which the multiple wire feed apparatus of  FIG. 1  can be used. 
       FIG. 10  is a schematic block diagram of a control for operating the multiple wire feed apparatus of FIG.  1 . 
       FIG. 11  is a flow chart of an operation of the multiple wire feed apparatus of FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1 and 2 , a multiple wire feed apparatus  20  is comprised of a first multiple wire feeder  22  and a second multiple wire feeder  24 . The second multiple wire feeder  24  is substantially a mirror image of the first multiple wire feeder  22 . Thus, parts specific to the first multiple wire feeder  22  will be designated by a number with an “a” suffix, and commonly functioning parts specific to the second multiple wire feeder  24  will be designated by the same number with a “b” suffix. Further, to facilitate a better understanding of the structure and operation of the first multiple wire feeder  22 , the second multiple feeder  24  is shown displaced or translated from its normal location. The normal location of the second multiple wire feeder  24  is illustrated by the phantom lines  26 . Therefore, the first and second multiple wire feeders  22 ,  24 , are normally disposed immediately adjacent each other as shown in  FIGS. 5-8 . 
   The structure of the first multiple wire feeder  22  will be described in detail; and the explanation of the first multiple wire feeder  22  applies equally to the second multiple wire feeder  24 . The first multiple wire feeder  22  has a pair of guide bars  28  that are rigidly connected to a supporting structure  30 . A carriage  32  has guide ways  34  that are shaped to receive the guide bars  28  such that the carriage  32  is supported by, and readily slides over, the guide bars  28 . A plurality of pairs of wire straightening rollers  36  are rotatably mounted on respective axles  38 ; and the axles  38  are rigidly mounted to the carriage  32 . Referring to  FIG. 3 , Each pair of wire straightening rollers  36  has grooves  40 ,  42 . The cross-sectional profile of the grooves  40 ,  42  and the centerline spacing of the axles  38  are selected such that the grooves  40  provide a wire straightening function for a first wire  44  of a first diameter or gage, and the grooves  42  provide a wire straightening function for a second wire  46  of a different, second diameter. Prior to entering the wire straightening rollers  36 , the different first and second wires  44 ,  46  are fed from a coil in a known manner and pass through an aperture  48  of a block  50  mounted at a rear end of the carriage  32 . 
   As shown in  FIGS. 1 and 2 , a first wire guide block  52  is rigidly attached at a forward end of the carriage  32 . The first wire guide block  52  has first and second grooves or wire paths  54 ,  56 , respectively. The wire path  54  has a first end  58  positioned to receive the first wire  44  from the grooves  42  of the wire straightening pulleys  36 . The wire path  56  has a first end  60  positioned to receive the wire  46  from the grooves  40  of the wire straightening rollers  36 . 
   An actuator  62 , for example, an electric solenoid, a fluid cylinder, a device that converts rotary motion into linear motion, etc., is rigidly connected to the supporting structure  30 . The carriage  32  is mounted to a distal end of an operating element  64  of the actuator  62 , for example, an armature, a cylinder rod, a rack, etc. Thus, the linear actuator  62  is operable to translate or reciprocate the carriage  32  and first wire guide block  52  in a direction generally parallel to centerlines  43  of the axles  38 . The carriage  32  and first wire guide block  52  are reciprocated in order to align one of the second ends  66 ,  68  of the respective wire paths  54  or  56  with an input side of a powered wire feeding device  69 . 
   The wire feeding device  69  has a powered wire feed roller  70  that is connected to an output shaft  72  of a feed motor  74  that, in turn, is rigidly connected to supporting structure  30 . A pressure roller  76  is rotatably mounted to the distal end of an axle  78  having a proximal end rigidly connected to the supporting structure  30 . Referring to  FIGS. 1 and 4 , the feed roller  70  and pressure roller  76  have opposed respective grooves  80 ,  82  that are sized to accept a range of different wire diameters. A pressure actuator  84 , for example, a fluid cylinder, or any other device for applying a force in a linear direction, is also rigidly mounted to the supporting structure  30 . The pressure actuator  84  has a movable element, for example, a cylinder rod, that via a mechanical link or otherwise, applies a force on the axle  78  in response to an operation of the pressure actuator  84 . 
   The feed and pressure rollers  70 ,  76  have respective grooves  80 ,  82  that having respective cross-sectional profiles adapted to receive coil wire. When the pressure actuator  84  is in a state in which little or no force is applied to the axle  78 , the pressure roller  76  separates slightly from the feed roller  70 ; and thus, the groove  82  of the pressure roller  76  also separates from the groove  80  of the feed roller  70 . The grooves  80 ,  82  separate by a distance sufficient to permit a wire, for example, a wire extending from an outer end  66 ,  68  of one of the grooves of the first wire guide block  52 , to move laterally into or out of a location between the grooves  80 ,  82 . 
   As shown in  FIG. 5 , the feed and pressure rollers  70 ,  76  are located such that a wire extending from the first wire guide block  52  can be positioned between the grooves  80 ,  82 . Thus, when the actuator  84  applies a force against the axle  78 , the pressure roller  76  moves closer to the feed roller  70 ; and the groove  82  presses the wire against the groove  80 . The pressure actuator  84  causes the pressure roller  76  to apply a sufficient force against the wire between the grooves  80 ,  82 , so that the feed roller  70  can pull the wire through the wire straightening rollers  36  and the first wire guide block  52 . In some applications, the operation of the pressure actuator  84  may cause the applied force on the pressure roller  76  to vary in order to maintain a desired tension force on the wire passing between the grooves  80 ,  82 . 
   A second wire guide block  86  is rigidly mounted to the supporting structure  30  adjacent output sides of the powered wire feeding devices  69   a ,  69   b  and has first and second grooves or wire paths  88 ,  90 , respectively. The second guide block  86  is positioned such that a first end  92  of the first wire path  88  is positioned to receive a wire being fed from between the grooves  80 ,  82  of the respective feed and pressure rollers  70 ,  76 . As shown in  FIG. 5 , a first end  94  of the wire path  90  is positioned to receive a wire being fed from a groove of feed roller  70   b . The wire paths  88 ,  90  have respective second ends  96 ,  98  that intersect an outlet channel  100  of the second wire guide block  86 . Thus, with the multiple wire feed apparatus  20  in the state illustrated in  FIG. 5 , the feed and pressure rollers  70   a ,  76   a  are operative to feed a first wire  44  of a first diameter through grooves  42  of wire straightening rollers  36 , through wire path  54  of the first wire guide block  52 , along guide path  88  of the second wire guide block  86  and out the outlet  100 . The wire is then fed to a wire coiling machine illustrated in FIG.  9 . 
   The structure and operation of a spring coiling machine  110  of  FIG. 9  is similar to that shown and described in U.S. Pat. No. 5,713,115 that is hereby incorporated by reference in its entirety herein. The spring coiling machine has a bending device  112  comprising essentially a bending tool implemented as a bending roller  114  and a pitching tool  116 . The bending roller  114  is driven by a servo motor  118 , and the pitching tool  116  is moved by a servo motor  120 . A wire cutting action is provided by a servo motor  122  that rotates a cam  124 . The outer circumference of the cam  124  contacts a roller  126  that is rotatably disposed at a pivotal portion of an articulated lever  128 . The articulated lever  128  is pivotally supported at one end by a pivot axis  130 . The opposite end is pivotally connected to an upper cutter  132  that is positioned in an opposing relationship with a stationary lower cutter  134 . The servo motors  118 ,  120 ,  122  are operated in a manner such that the bending roller  114  and pitching tool  116  are effective to bend a wire  44  into a spring coil having a desired diameter and coil pitch. The servo motor  122  is then operated such that the wire is cut between the respective moving and stationary cutters  132 ,  134 . The process is repeated to automatically form other coils from the wire  44  as it is fed to the spring coiling machine  110 . 
   The actuators and motors of the multiple wire feed apparatus  20  and spring coiling machine  110  are controlled by a programmable controller  140  that is electrically connected to user input/output (“I/O”) devices  142 , for example, pushbuttons, keyboard, visual displays, lights, printer, etc. Using one or more of the I/O devices  142 , a user is able to input a program identifying the basic specifications of a desired spring coil. The control  140  is electrically connected to a microcontroller  144  that is responsive to the desired spring coil specifications and provides outputs to various motor controllers  146  that control motors  118 ,  120 ,  122  on the spring coiling machine such that the desired spring coil is made. Feedback devices  148  provide feedback information to the motor controllers  146  to facilitate the control of the motors  118 ,  120 ,  122  in accordance with the commanded operation provided by the microcontroller  144 . The microcontroller  144  also provides command signals to motor controllers  150  that are operative to operate motors  74   a ,  74   b  of the multiple wire feed apparatus  20  in order to initiate and terminate a wire feed at the appropriate times. Feedback devices  152  facilitate the control of the motors  74   a ,  74   b  by the motor controllers  150 . A programmable logic controller  154  is also electrically connected to the programmable controller  140  and provides output signals to the actuators  84   a ,  84   b ,  62   a ,  62   b  of the multiple wire feed apparatus  20 . 
   In use, when making spring coils for furniture, for example, mattresses, in order to support a human body in the proper posture when lying on a mattress, it is sometimes desirable to provide a mattress with spring coils at different locations having differing stiffnesses or spring constants to conform with the loading imposed by a human body. For example, a mattress may be divided into as many as five sections, a head section, an chest section, a waist section, a hip section and a leg section, wherein each section has spring coils of a specific and often different stiffness. Thus, in order to use spring coils of the same diameter, the spring coils for each section must be made with wire of a different size, that is, diameter. Using the example above, assume that the coils for the chest section are a medium stiffness, the coils for the hip section are a heavy stiffness and the coils for the head, waist and leg section are a light stiffness. The number of coils and their stiffness will vary depending on the mattress size, its target market, posture support profile, etc. Once designed, the number of coils to be made for each mattress section and the wire used is input and stored in the microcontroller  140 . Further, the bender roller and pitch settings for each of the wire sizes for a spring coil diameter is also input and stored in the microcontroller  140  and/or the microprocessor  144 . 
   To make spring coils for a mattress, the user first identifies or inputs either, a particular type of mattress or, the number of coils and wire size to be used for each mattress section. Upon initiating a cycle of operation, the microcontroller  140  causes the bending roller  114  and pitching tool  116  to be adjusted, so that a spring coil of a desired diameter will be made from a first wire size to provide a less stiff spring coil for the head section. The microcontroller  140  then commands the multiple wire feed apparatus of  FIG. 1  to begin feeding the first wire to the spring coiling machine of FIG.  9 . As each coil is made, the microcontroller  140  causes the motor  122  to cut the coil and release it from the coiling machine. Another machine assembles the spring coils in a known manner. 
   After a number of coils have been made so that the head section of the mattress is complete, the microcontroller  140  commands the multiple wire feed apparatus to switch to a second wire size, for example, a heavier wire to make stiffer spring coils for the chest section of the mattress. Simultaneously, the microprocessor  144  causes the bending roller  114  and pitching tool  116  to be adjusted, so that a spring coil of the desired diameter will be made from the second, heavier wire size. The microcontroller  144  causes the heavier wire feed to be initiated, and a desired number of stiffer spring coils for the chest section of the mattress are made. Thereafter, the microcontroller  140  causes the multiple wire feed apparatus  20  to switch to a third, lighter gage wire, so that a number of coils are made for the waist section that have a lighter stiffness. After adjusting the bending roller and the pitching tool for the smaller size wire, the process is repeated in order make lighter stiffness coils for the waist section of the mattress. The above process is repeated using a heavier gage wire for the hip section and a lighter gage wire for the leg section. Thus, the multiple wire feed apparatus  20  permits spring coils to be continuously made from different wire sizes or gages without manually changing tooling on the machine. 
   The operation of the multiple wire feed apparatus is generally illustrated in FIG.  11 . First, at  950 , a determination is made whether the cutter  132  has completed its operation. If so, then at  952 , the microcontroller  144  determines whether a new wire size is required. Assume that the spring coils are currently being made from the wire  44  and that a different wire size is not desired at this time. The PLC  154  then determines, at  954 , whether a wire feed start command has been received. If so, the PLC proceeds, at  956 , to engage the active pressure roller  76   a  by changing the state of an output signal to the actuator  84   a . Changing the state of the actuator  84   a  causes pressure to be applied to the axle  78   a , thereby moving the pressure roller  76   a  toward the feed roller  70   a  and engaging the wire  44  between the grooves  80 ,  82 . The PLC  154  then provides a signal to the microcontroller  144  indicating that the pressure roller  76   a  is engaged. 
   Thereafter, at  958 , the microcontroller  144  provides an output signal to the motor control  150  that causes the feed motor  74   a  to run. Upon operating the feed motor  74   a , the wire  44  is pulled off its supply coil, through wire straightening rollers  36  and through the first wire feed guide block  52 , and the wire  44  is pushed across the second wire guide block  86  into the spring coiling machine  110  of FIG.  9 . The microcontroller  144  continues to operate the spring coiling machine  110  until a desired number of coils have been manufactured. It should be noted that in that process, the feed motor  74   a  may or may not be stopped during the operation of the wire cutter  132  as each spring coil is manufactured. If the feed motor  74   a  is stopped, a command is detected at  960 , by motor controller  150  which, in turn, at  962 , provides outputs to the motor  74   a  bringing it to the desired stopped state. 
   After a number of spring coils have been made from the wire  44 , it may be desirable to manufacture a number of stiffer spring coils from a thicker wire, for example, wire  46 . The microcontroller  144  then, at  964  of  FIG. 11 , provides a command to the motor controller  150  commanding the motor controller  150  to reverse the operation of the wire feed motor  74   a . The end of the wire  44  is currently located at the wire cutter  132 . By reversing the operation of the feed motor  74 , the wire  44  is retracted from the wire cutter  132 . Next, at  966 , the microcontroller determines whether the next wire to be used is on the same carriage, for example, carriage  32   a , or on another carriage, for example carriage  32   b . The wires  44  and  46  are fed off of the same carriage, and therefore, the microcontroller  144  stops the reverse wire feed so that the end of the wire  44  is at the same position as the wire  46  in FIG.  5 . Therefore, when the wire  44  reaches the position that is shown in  FIG. 6. , the motor controller  144 , at  968 , commands the wire feed motor  74   a  to stop. Further, at  970 , the PLC  154  releases the active pressure roller  76   a  by commanding the actuator  84   a  to change states. Thereafter, at  970 , the microcontroller  144  commands the PLC  154  to actuate the carriage actuator  62   a . Since the wire  44  was initially being fed through the feed roller  76   a , the actuator  62   a  was in its extended state as illustrated in FIG.  5 . The PLC  154  operates the actuator  62 , so that it moves to its retracted state as illustrated in  FIG. 6 , thereby moving the carriage  32   a  and first wire guide block  52   a  slightly upward as viewed in FIG.  6 . That motion slides the cut end of the wire  44  from between the grooves  80 ,  82  of the respective feed and pressure rollers  70   a ,  70   b . Further, the cut end of the wire  46  is moved to an inlet between the grooves  80 ,  82 , thereby placing the wire  46  at a feed location. 
   After receiving a signal from the PLC  154  that the wire  46  is in the feed position, the microcontroller  144  then proceeds, at  954 , to initiate a wire feed command. The PLC  154  first, at  956 , engages the active pressure roller  76   a  and thereafter, at  958 , operates the active feed roller  70   a  in a manner as previously described. The microcontroller  144  in addition operates the wire coiling machine  110  to produce a number of spring coils with the different sized wire  46 . If the wire  46  has a thicker diameter, the spring coils made therefrom will be stiffer, feel firmer and provide more support for the user. If the wire  46  has a smaller diameter than the wire  44 , the spring coils will be less stiff, feel softer and provide less support to the user. Thus, using the apparatus just described, spring coils for furniture can be automatically and continuously produced from different wire sizes in order to provide spring coils of differing thickness. Further, the diameter in pitch of spring coils made from each size wire may also be adjusted to provide further variations in stiffness. 
   As shown in  FIG. 6 , the multiple wire feed apparatus  20  has a second multiple wire feeder  24  that is substantially identical to, but a mirror image of, the first multiple wire feeder  22 . The second multiple wire feeder  24  has a capability of providing two additional wires  45 ,  47 , of different sizes, so that there is even greater flexibility in using the spring coiling machine  110  of FIG.  9 . The wires  45 ,  47  pass through wire straightening rollers  36   b  and across a first wire guide block  52   b  along first and second wire paths  54   b ,  56   b . As shown in  FIGS. 1 and 6 , the wire  45  passes through grooves  80   b ,  82   b  of the respective feed and pressure rollers  70   b ,  76   b  and along wire path  90  of the second wire guide block  86 . 
   In switching from wire  46  to wire  45 , the process of  FIG. 11  is executed as previously described, however, at step  966 , in retracting the wire  46 , the microcontroller  144  determines that next wire to be used, wire  45 , is not on the same carriage  32   a  as the currently active wire  46 . Therefore, the microcontroller  144  stops the reverse wire feed of the wire  46 , so that the end of wire  46  is at the same position as the wire  45  in FIG.  6 . Therefore, when the wire  46  reaches the position that is shown in  FIG. 7. , the motor controller  144 , at  974 , commands the wire feed motor  74   a to stop. Thereafter, the microcontroller  144 , at  976 , switches the active feed from feed and pressure rollers  70   a ,  76   a  to feed and pressure rollers  70   b ,  76   b . Thereafter, at  956 , when a wire feed command is detected, the microcontroller  144  provides a command to the PLC  154  to engage the active pressure roller. 
   The PLC  154  then switches the state of the pressure actuator  84   b , thereby causing the pressure roller  76   b  to secure the wire  45  in the grooves  80   b ,  82   b  of the respective feed and pressure rollers  70   b ,  76   b . Next, at  958 , the microcontroller  144  runs the active feed roller by providing command signals to the motor controller  150   b  that, in turn, operates the active feed motor  74   b  in the forward direction. Thus, wire  45  is pulled from a feed coil, through wire straightening rollers  36   b  and along wire path  54   b  of the wire guide block  52   b . Further, rotation of the active feed roller  70   b  pushes the wire  45  along wire path  90  of the second wire guide block  86  and into the spring coiling machine  110 . Thus, a number of spring coils are made from wire  45  which is a different size than the wires  44  and  46 . 
   If a change in spring coil stiffness is again required, the second multiple wire feeder can be used to provide a fourth wire  47  of a different size from the wires  44 ,  45 ,  46 . In a manner similar to that described with respect to the change from wire  44  to wire  46 , since the wire  47  is on the same carriage  32   b  as the wire  45 , the wire  45  is retracted to a position adjacent the feed roller  70   b  as shown in FIG.  8 . The feed roller  70   b  is stopped, and the pressure roller  76   b  is disengaged. Next, the carriage actuator  62   b  is operated so that the wire  47  is moved into a feeding relationship with respect to the feed and pressure rollers  70   b ,  76   b . As shown in  FIG. 7 , to engage wire  45  in a feeding relationship, the actuator  62   b  is retracted. Therefore, in order to feed the wire  47 , the actuator  62   b  is extended, thereby moving or translating the carriage  32   b  and wire feed block  56   b  slightly upward to a position shown in FIG.  8 . That motion moves the wire  45  out of, and moves the wire  47  into, the grooves  80   b ,  82   b  of the respective feed and pressure rollers  70   b ,  76   b . Therefore, the next time the feed motor  74   b  is operated, the feed roller  70   b  is operative to pull the wire  47  through the wire straightening rollers  36   b  and across the wire path  56   b  of the first wire guide block  52   b . Further, the feed roller  70   b  pushes the wire  47  along the wire path  90  of the second wire guide block  86  and into the spring coiling machine  110  of FIG.  9 . Thus, spring coils are continuously made from the wire  47  which is a different wire size from the wires  44 ,  46 ,  45 . 
   The multiple wire feed apparatus described herein provides a simple and reliable apparatus for automatically and rapidly changing wires to an input of a spring coiling machine. The multiple wire feed apparatus permits the use of the same tooling on a spring coiling machine to make spring coils using different sizes of wires. Further, the changing of wire sizes with the multiple wire feed apparatus is accomplished automatically without the need for manual labor. Thus, the multiple wire feed apparatus is especially useful in making spring coils for furniture such as mattresses and seating furniture in which coil springs of a common diameter but a differing stiffness are often desired. By providing for the automatic and continuous manufacture of spring coils from wires of different sizes, the multiple wire feed apparatus permits such furniture to be made more quickly and at a substantially reduced cost. 
   While the invention has been illustrated by the description of one embodiment and while the embodiment has been described in considerable detail, there is no intention to restrict nor in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those who are skilled in the art. For example, in the described embodiment, four wires  44 ,  45 ,  46 ,  47  are selectively used to make spring coils of differing stiffness. As will be appreciated, similar structure can be used to feed additional wires. Further, in  FIG. 10 , the PLC  154  is shown electrically connected to the microcontroller  140 . As will be appreciated, depending on a desired control architecture, the PLC  154  can be electrically to either the microcontroller  140  or the microprocessor  144  or both of those devices. 
   Therefore, the invention in its broadest aspects is not limited to the specific details shown and described. Consequently, departures may be made from the details described herein without departing from the spirit and scope of the claims which follow.