Patent Publication Number: US-4255917-A

Title: String packaging machine and apparatus

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to the packaging of lengths of resilient material and particularly filamentary material. More specifically, this invention is directed to apparatus for coiling elongated resilient elements and thereafter retaining such elements in coiled form. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character. 
     (2) Description of the Prior Art 
     While not limited thereto in its utility, the present invention is particularly well suited for use in the packaging of strings for musical instruments. The discussion below will, accordingly, be primarily in terms of the solution of problems which, while not unique thereto, are particularly important to the packaging of such music strings. 
     Numerous apparatus and techniques for arranging filamentary material in an annular pack by forming it into a succession of superimposed generally circular loops have, over the years, been proposed and in some cases implemented. These prior techniques and apparatus have shared common deficiencies. With particular regard to those prior techniques and apparatus suitable for use in the handling of finished products having a high degree of resiliency, music strings for example, the principal deficiency has been the requirement for a significant amount of manual labor. Thus, in spite of numerous attempts to automate, the prevalent practice in the music string industry today is to coil the product by hand, manually &#34;tuck&#34; the ends around the formed coil so that the coil shape will be retained and thereafter either insert the coiled product by hand into a package or into a machine which subsequently accomplishes the final packaging. The cost of this hand labor may amount to as much as 40% of the total cost of the finished product. Further, the hand coiling of the music string product may result in excessive deformation which permanently damages the string. Additionally, points of direct finger contact with the product are potential sites of corrosion. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the above briefly discussed and other deficiencies and disadvantages of the prior art by providing a novel and improved technique and apparatus for automatically coiling and prepackaging and/or packaging resilient filamentary material which is manufactured in straight form. The method and apparatus of the present invention eliminate the damage due to execessive deformation of the product, which is inherent in manual coiling operations, and minimize handling of the product, to thereby minimize the possibility of chemical damage such as that attributable to corrosion. 
     Apparatus in accordance with a preferred embodiment of the present invention is characterized by a conduit which receives the product, for example a music string, to be packaged. This conduit, at the discharge end, communicates with a coiling annulus which, in part, is defined by a planar support surface. Means are provided which permits a sheet of heat sealable packaging material to be positioned on the support surface in registration with the coiling annulus. The leading end of the music string is directed, preferrably pneumatically, into the coiling annulus where it is engaged in a capture slot. The remainder of the music string, or other product, is then drawn from the conduit into the coiling annulus by causing relative rotation between the capture slot and the conduit. A plurality of knives are positioned in slots in coiling annulus support surface and, when the coiling step is completed, the knives are rotated to shear tabs out of the sheet of packaging material. These tabs are folded over the coiled product by the knives and into contact with the surface of the sheet to which they instantly adhere thereby retaining the product in the coiled form. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawing wherein like reference numerals refer to like elements in the several FIGURES and in which: 
     FIG. 1 is a schematic side elevation view, partly in section, of apparatus in accordance with a first embodiment of the present invention; 
     FIG. 2 is a plan view taken along the lines 2--2 of FIG. 1; 
     FIG. 3 is a cross-sectional side elevation view taken along the line 3--3 of FIG. 2; and 
     FIG. 4 is a perspective view depicting the pre-packaged coiled product as it exits from the apparatus of FIGS. 1-3, FIG. 4 also showing further packaging of the product. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT: 
     With reference now to the drawing, and particularly jointly to FIGS. 1-3, apparatus in accordance with a first embodiment of the present invention is shown schematically. The disclosed apparatus includes, as major sub-systems, an immobile base, which has been indicated generally at 10, and a vertically movable feeding and coiling mechanism, indicated generally at 12. The feeding and coiling mechanism 12 includes a &#34;mandrel&#34; subassembly and a feed tube subassembly which is rotatable relative to the mandrel subassembly. The disclosed embodiment of the present invention also includes a pneumatic feed subassembly, indicated generally at 13, which is vertically movable with respect to the feeding and coiling subassembly 12. 
     The base subassembly 10 functions as a support over which a tape of heat sealable paper or plastic 14 will be fed. The heat sealable paper or plastic sheet material will be played out from a supply reel, not shown, and will be advanced through the apparatus in stepwise fashion. In the apparatus the tape 14 is supported on a platen 16 which is heated; the heat source typically being an electrical resistance heater as indicated at 18. The platen 16 will, of course, be selected so as to be commensurate in size with the coiled dimension of the product to be packaged and the apparatus will include a supporting base 20 which surrounds platen 16. Supporting base 20 includes cavities or slots, such as indicated at 22 in FIG. 1, having rotatable shearing knives 24 positioned therein. 
     In the disclosed embodiment, as may best be seen from FIG. 2, four orthogonally arranged shearing knives 24 are mounted in separate slots in base 20. The shearing knives 24 are mounted for rotation about shafts 26. The knives 24 are gear driven, so as to be operated simultaneously, by means of engagement of a gear sector 28 (FIG. 1), which forms a part of the knife, with a pinion gear 30. The manner in which the four knife engaging gears are simultaneously driven may best be seen from FIG. 2 and includes pairs of bevel gears 32, 34 at each of the four corners of a continuous drive train. A first of gears 32 is driven by drive shaft 36 which, in turn, is caused to be rotated in the manner to be described below. 
     The base member 20 has, extending upwardly therefrom, at least two guide pins 38. Pins 38 are press fit or otherwise affixed to base 20 and at all times engage the vertically movable feeding and coiling subassembly 12. As may be seen from FIG. 2, the pins 38 are outside the area occupied by the tape 14 as it is fed through the apparatus. The base member 20 is also provided with a blind hole which is engaged by locking pin 62 on the feeding and coiling subassembly 12. Pin 62, in the process of moving into engagement with the hole in base member 20, will punch through tape 14. 
     The vertically movable feeding and coiling subassembly 12 includes a shearing block 40 which is provided with slots 42 through which the shearing knives 24 may pass when rotated. The shearing block 40 is affixed to a tubular coil retainer 44 which is also provided, at the lower end thereof, with slots through which the knives 24 may pass. The coil retainer tube 44 is further provided with a &#34;capture&#34; slot 46 which may best be seen from joint consideration of FIGS. 2 and 3. A pair of &#34;barbs&#34; 48 extend into slot 46. The coil retainer tube 44 will typically be of two piece construction with the lower end portion 44A, which defines the capture slot, being comprised of a nonconductive material. The barbs 48, which are embedded in the lower portion 44A of the tube 44, will be metallic. Barbs 48 will be electrically connected in the energization circuit for an activator 49 which may include a pneumatic or hydraulic cylinder or a solenoid for the purpose to be described below. The inner diameter of the lower end portion 44A of retainer tube 44 defines the outer wall of a coiling annulus 86. 
     The feeding and coiling subassembly 12 also includes a rotatable tube 52 which is mounted coaxially with respect to the coil retainer tube 44. The rotatable tube 52 is provided, intermediate its ends, with an inner bulkhead 54. Tube 52, at its lower end, is also provided with an outwardly extending flange 56. Flange 56 defines the upper wall of the coiling annulus 86. A &#34;coiling drum&#34; 58 is suspended from rotatable tube 52 on a bolt 60 which engages the inner bulkhead 54 as shown. The &#34;coiling drum&#34; 58 forms the inner diameter of coiling annulus 86 and thus functions as a mandrel. The aforementioned locking pin 62, which engages the base member 20, extends from the &#34;coiling drum&#34; 58. Rotation of tube 52 relative to &#34;coiling drum&#34; 58 is possible since the &#34;coiling drum&#34; 58 is free to rotate on the head of retention bolt 60. The continuous engagement of the guide pins 38 with the shearing block 40, which is in turn affixed to the coil retainer tube 44, permits rotation of tube 52 relative to coil retainer tube 44; the latter motion being facilitated by bearings such as indicated at 64. 
     Vertical motion of subassembly 12 with respect to the base subassembly 10 is accomplished by means of a suitable actuator which has been schematically shown in the drawing as a hydraulic or pneumatic cylinder 66 having its piston rod 68 attached to the shearing block 40. The actuator which produces the vertical motion of subassembly 12 can, alternatively, be affixed to retainer tube 44. Vertical motion of shearing block 40 is transmitted, in the disclosed embodiment, via coil retainer tube 44 and bearings 64 to rotatable tube 52 and, via drum retention bolt 60, to the &#34;coiling drum&#34; 58. Rotational movement of tube 52 is produced, in the disclosed embodiment, by a chain and sprocket drive operated by motor 50; the drive including a slip clutch 70, a first sprocket 72, chain 74 and a further sprocket 76 affixed to the outside of tube 52. In the disclosed embodiment motor 50 is continuously running and chain 74 is driven via clutch 70 when a locking mechanism operated by solenoid 49 released a pin carried by the chain. Solenoid 49 will be momentarily energized by the establishment of an electrical circuit between the &#34;barbs&#34; 48 positioned in capture slot 46. It will be understood, however, that there are other ways in which the sensing of the receipt of a first end of the product to be coiled in slot 46, for the purpose of energizing solenoid 49, may be accomplished. Thus, by way of example, the solenoid 49 may be manually energized by an operator controlled switch. In the disclosed embodiment one complete revolution of chain 74 will be commensurate with coiling of the entire string or other product in annulus 86. The lock pin on chain 74 will be engaged by the locking mechanism operated by solenoid 49, via a camming surface thereon, to terminate rotation of tube 52 after each complete rotation of the chain. 
     Continuing with a discussion of the feeding and coiling subassembly 12, a conduit 80 is mounted within the rotatable tube 52 and extends generally vertically along the axis of tube 52 for a length approximately equal to the length of the product to be coiled. As shown in FIGS. 1 and 2, the product to be coiled is a music string which has been indicated at 82. String 82, in the customary manner, has a &#34;ball&#34; 84 at the first end thereof. In the disclosed embodiment it is the ball 84 which will bridge the barbs 48 thus completing the energizing circuit for solenoid 49. The conduit 80, as it approaches the bottom of tube 52, is guided outwardly from the axis of tube 52 so as to lead the product to be coiled and packaged into the coiling annulus 86. In one reduction to practice of the invention, the conduit 80, &#34;coiling drum&#34; 58 and the lower portion 44A of the coil retainer tube 44 were comprised of a suitable nonconductive material such as polytetrafluorethylene. The conduit 80 passes through the inner bulkhead 54 and then through the wall of the rotatable tube 52. Considering the disclosed embodiment of the apparatus, in a side elevation view the conduit 80 would approach the coiling annulus 86 at an acute angle, typically in the range of 20° to 30° to the plane of the coiling annulus 86. Considered in a plan view, the conduit 80 spirals outwardly from the center line of the rotating tube 52, through the wall of tube 52, and then terminates in an arc having a radius approximately equal to that of the coiling annulus 86. As may be seen from FIG. 1, at its lower end the conduit 80 penetrates the lower flange 56 on rotating tube 52. A resilient wire product delivered down conduit 80 will thus be discharged into the coiling annulus 86 along the outer wall thereof. 
     At the upper end of the feeding and coiling subassembly 12, a product receiving vestibule defining member 90 is mounted on the rotating tube 52. Member 90 is provided with a conically shaped opening which converges to the upper end of conduit 80. The upper end of conduit 80 is retained in the lower end of the member 90 by means of a gasket 92 which will typically be comprised of the same material as conduit 80. A first end of a product to be packaged, for example the music string 82, will be guided down the conical wall of member 90 into the upper end of conduit 80 and will typically drop down conduit 80 to the position shown in FIG. 1 where the conduit 80 is beginning to be directed outwardly. Conduit 80 will be sufficiently long relative to the product being packaged such that the upper end of the product will be below member 90 when the free movement of the product is stopped by the change in direction of conduit 80. 
     The pneumatic feed subassembly 13 includes a conically shaped plug 94 which is provided, on its axis, with a conduit which defines a passage 96. The plug 94 is sized and shaped so as to be received in the vestibule defining member 90 in such a manner that a substantially airtight seal will be formed at least between the lower end of plug 94 and the wall of member 90. The upper end of passage 96 is connected to a source of compressed gas which has been indicated schematically at 98. There will, of course, be a normally closed valve, for example valve 100, which may be operated to establish communication between source 98 and passage 96 at the appropriate time. Plug 94 is moved into and out of the conically shaped opening vestibule defining member 90 by means of a pneumatic or hydraulic cylinder 102. Cylinder 102 may be automatically actuated, for example by means which senses the presence of a product to be packaged in the upper end of conduit 80, or manually actuated by an operator of the apparatus. The valve 100 will be operated to the open position in response to the seating of plug 94 in member 90 and this may be accomplished by a suitable sensor associated with the piston rod of actuator 102. If rotation of tube 52, and thus of vestibule defining member 90, is to be accomplished before return of plug 94 to the position depicted in FIG. 1, a rotating seal will be established between the conduit which defines the passage 96 in plug 94 and a supply conduit from source 98 and a substantially frictionless connection will also be established so as to permit rotation of plug 94 relative to the mechanical connection to the piston rod of actuator 102. 
     In the operation of the disclosed embodiment of the invention, the feeding and coiling subassembly 12 will initially be raised, by means of actuator 66, above the base subassembly 10 and the pneumatic feed subassembly 13 will also be displaced from the upper end of the subassembly 12 as shown. The spacing of the feeding and coiling subassembly 12 from base subassembly 10 will be by a distance equal to the length of the locking pin 62 plus the thickness of the coiled product and any additional necessary clearance. The heat sealable paper tape or plastic 14 is indexed across the heated platen 16 a sufficient distance so as to place a length of packaging material of suitable dimensions in position to have a coiled product deposited thereon. Thereafter, the actuator 66 will be operated to lower the feeding and coiling subassembly 12 to the position shown in FIG. 1. The vertical movements of the subassembly 12 will be guided by pins 38. The product, for example the music string 82, is then introduced into the product receiving vestibule defined by member 90 and will be guided downwardly into conduit 80. The product 82 will, either under the influence of gravity or as a result of manual insertion, move down conduit 80 approximately to the position shown in FIG. 1. With the product 82 at rest in conduit 80, and its presence typically being sensed by a proximity sensor such as indicated schematically at 104, the actuator 102 will be energized and will cause the sealing cone or plug 94 to be lowered into member 90. When a seal has been established between plug 94 and member 90, the valve 100 will open and a slug of gas will be admitted to the upper end of conduit 80. Due to the relative sizing between the ball 84 at the end of music string 82 and the inner diameter of conduit 80, the ball will act as a piston and thus the pressurized gas will force the music string 82 down the spiralled lower portion of tube 80 and eject the ball 84 into the coiling annulus 86. Under the influence of the pressurized gas, the ball will move along annulus 86 until it encounters the capture slot 46. When the ball enters capture slot 46 it will be engaged by the barbs 48 and thus a circuit to energize solenoid 49 will be completed. Energization of solenoid 49 will permit motor 50 to drive tube 52 through slip clutch 70 and chain 74. Rotation of tube 52 will cause the elements affixed thereto, including conduit 80, to rotate whereby the product will be drawn into the coiling annulus 86; the elements which define the inner, outer and bottom walls of annulus 86 being stationary. When a sufficient number of revolutions to extract the entire music string 82 or other product from conduit 80 have been completed, the rotation will be terminated in the manner described above. The rotation of tube 52 will be stopped at a point where the slots in flange 56 are in registration with the slots 42 in the shearing block 40. 
     The cessation of rotation of tube 52 may be sensed and employed as a command signal for a knife actuator which delivers rotational motion to shaft 36 whereby all four shearing knives 24 will be rotated about their respective axes simultaneously. The knives 24 will shear locking tabs out of the heat sealable tape 14 and these tabs are folded by the knives 24 about the coiled product in annulus 86 and into contact with the upper surface of the tape which is radially disposed toward the center of the annulus and over the heated platen 16. Contact of the sheared tabs, as indicated at 106 in FIG. 4, with the upper surface of the tape produces instant adhesion of the tabs to the base material thereby locking the coiled product in the coiled position and to the tape. The knives 24 may, of course, be energized manually by observing the stopping of chain 74. 
     After the tabs 106 have been sheared from tape 14 and wrapped over the coiled product, the knives 24 are rotated back to their initial position within the base 20 and the subassemblies 12 and 13 are both raised to their initial positions. The upward movement of the feeding and coiling subassembly 12 will raise locking pin 62 so that it clears the coiled products. The upward movement of subassembly 12 also releases the ball 84 at the end of the music string 82 from the capture slot 46 since the &#34;barbs&#34; 48 are slightly angled downwardly as shown in FIG. 3. The tape 14 is thereafter indexed so as to place a fresh, unsheared area of packaging material in position to receive the next product unit. 
     As represented in FIG. 4, the coiled product captured on tape 14 may subsequently be completely encapsulated by draping heat sealable plastic or paper over the top and bottom sides of tape 14. If such complete encapsulation is desired, typically a continuous &#34;belt&#34; of packaged product will be maintained. Alternatively, each of the coiled products may be sheared from the tape and placed in individual packages such as, for example, heat sealable bags. 
     While a preferred embodiment has been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it will be understood that the present invention has been described by way of illustration and not limitation.