Sewing system with thread draw tension adjusting capability and a method of adjusting the thread draw tension

Abstract

The combination of a bobbin assembly and a support for the bobbin assembly. The bobbin assembly has a core around which a supply of thread can be wrapped. The core has a rotational axis. The bobbin assembly further has a first flange with first and second oppositely facing surfaces, with the first surface bounding a storage space for thread wrapped around the core. The support allows the bobbin assembly to rotate around the rotational axis. The support has a third surface facing the second surface with the bobbin assembly operatively connected to the support. The bobbin assembly and support are magnetically attracted to each other with a force of a first magnitude with the bobbin assembly and support in a first state. The force resists rotation of the bobbin assembly around the rotational axis. At least one of the bobbin assembly and support is reconfigurable to cause the bobbin assembly and support to be one of a) not magnetically attracted to each other and b) magnetically attracted to each other with a force of a second magnitude, that is different than the first magnitude, with the bobbin assembly and a support in a second state.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to sewing systems utilizing a bobbin assembly, upon which a supply of thread is wrapped, and a support, relative to which the bobbin is rotated as the thread is draw off of the bobbin assembly. More particularly, the invention is directed to a method and structure for selectively, variably controlling tension on the thread as the thread is drawn off of the bobbin assembly.

[0003] 2. Background Art

[0004] In one conventional sewing system, a supply of thread is wound around a bobbin. The bobbin is mounted on a post within a case for rotation relative to the post axis. Thread is directed from the bobbin through an opening in the peripheral wall of the case to be engaged by a rotary loop taker. During system operation, the rotary loop taker exerts a force on the thread, i.e. a draw tension, that causes the bobbin to rotate in a manner that thread thereon is paid out.

[0005] An important factor in producing a consistent quality stitch is the ability to maintain a desired thread draw tension. Ideally, the force/thread draw tension required to extract the thread is maintained with a full thread supply up to the point that the thread supply is fully exhausted.

[0006] Various mechanisms have been devised to controllably adjust the thread draw tension. One such system, commonly used, employs a leaf-type spring element with a friction surface which confronts the outer wall of the case in a region at which the thread departs from the case opening . A captive frictional force, between the leaf-type spring element and case, can be varied by selectively setting an adjusting screw.

[0007] Another system for controlling thread draw tension is disclosed in U.S. Pat. No. 6,152,057. In this system, thread departing from the case opening is wrapped spirally around an elongate member to produce a controlled resistance to thread withdrawal. The degree of resistance can be set by strategically selecting a) the number of wraps of the thread around the elongate member, b) the frictional characteristics of the material on the exposed surface of the elongate member about which the thread is wrapped, etc.

[0008] It is also known to produce a force resisting rotation of a bobbin relative to a supporting case. This resisting force may be developed to prevent backlash and/or to control thread draw tension. An example of one such system is shown in U.S. patent application Ser. No. 09/794,702. In this system, frictional resistance is developed between a flange on the bobbin and an adjacent case surface. More specifically, flexible elements act between these surfaces to produce forces resisting rotation of the bobbin.

[0009] In U.S. patent application Ser. No. 09/825,417, magnetic attractive or repulsive forces are generated between the bobbin and case. These rotation resisting forces are predetermined and remain constant as the system is operated.

[0010] The sewing industry continues to seek out system designs that will permit a more constant thread draw tension to be maintained, regardless of the amount of thread on the bobbin. Those systems, described above, that require tension adjustment, may be labor intensive and may require skilled personnel to effect the necessary adjustments. In large systems, multiple adjustments must be made at different locations. Each time such an adjustment is made, trial and error may be required to assure that the appropriate thread draw tension has been set. Thus, these systems may become relatively expensive to operate.

[0011] Those systems that do not have any thread draw tension adjusting capability are limited in that the resistance to rotation is constant, as a result of which the thread draw tension will vary depending upon the volume of thread upon the bobbin. With such systems, it is common for bobbins to be removed from operation with a significant amount of thread thereon. The thread draw tension increases progressively as the thread supply is exhausted. At some point, the thread draw tension increases detrimentally to the point that stitch quality may be compromised. This point may be reached with a significant amount of thread remaining on the bobbin. Thus, significant thread waste may result, particularly in high volume operations.

SUMMARY OF THE INVENTION

[0012] In one form, the invention is directed to the combination of a bobbin assembly and a support for the bobbin assembly. The bobbin assembly has a core around which a supply of thread can be wrapped. The core has a rotational axis. The bobbin assembly further has a first flange with first and second oppositely facing surfaces, with the first surface bounding a storage space for thread wrapped around the core. The support allows the bobbin assembly to rotate around the rotational axis. The support has a third surface facing the second surface with the bobbin assembly operatively connected to the support. The bobbin assembly and support are magnetically attracted to each other with a force of a first magnitude with the bobbin assembly and support in a first state. The force resists rotation of the bobbin assembly around the rotational axis. At least one of the bobbin assembly and support is reconfigurable to cause the bobbin assembly and support to be one of a) not magnetically attracted to each other and b) magnetically attracted to each other with a force of a second magnitude, that is different than the first magnitude, with the bobbin assembly and support in a second state.

[0013] In one form, there is a magnetic assembly on one of the bobbin assembly and support that is attracted to a metallic portion on the other of the bobbin assembly and support. The bobbin assembly and support may be changed from the first state into the second state by separating a part of the magnetic assembly from the one of the bobbin assembly and support.

[0014] In one form, there is a metallic assembly on one of the bobbin assembly and support that is attracted to a magnetic portion on the other of the bobbin assembly and support. The bobbin assembly and support may be changed from the first state into the second state by separating a part of the metallic assembly from the one of the bobbin assembly and support.

[0015] In one form, the magnetic assembly has a first magnetic element. With the bobbin assembly and support in the second state, the first magnetic element is separated from the one of the bobbin assembly and support.

[0016] In one form, the magnetic assembly has first and second magnetic elements, and with the bobbin assembly and support in the second state, the first magnetic element is separated from the one of the bobbin assembly and support and the second magnetic element remains on the one of the bobbin assembly and support.

[0017] The first magnetic element may be maintained on the one of the bobbin assembly and support by being magnetically attracted to the one of the bobbin assembly and support.

[0018] The first magnetic element may be maintained on the one of the bobbin assembly and support by a releasable adhesive.

[0019] The first magnetic element may be otherwise bonded to the carrier.

[0020] The first magnetic element may be releasably threadably attached to one of the bobbin assembly and support.

[0021] In one form, the magnetic assembly is maintained on the one of the bobbin assembly and support by cooperating releasable connecting parts on the magnetic assembly and the one of the bobbin assembly and support.

[0022] In one form, the magnetic assembly has a first magnetic element which is separable from the one of the bobbin assembly and support by tearing a portion of the magnetic assembly to thereby change the bobbin assembly and support from the first state into the second state.

[0023] In one form, the magnetic assembly is provided on the second flange with the metallic portion at the third surface.

[0024] In one form, the support has a post which guides rotation of the bobbin assembly around the rotational axis and the magnetic assembly is on the post.

[0025] In one form, the magnetic assembly has first and second separate magnetic elements and a carrier for the first and second magnetic elements.

[0026] The carrier may have a weakened portion that can be torn to separate the first magnetic element from the one of the bobbin assembly and support to thereby place the bobbin assembly and support in the second state.

[0027] In one form, the carrier defines a first receptacle for the first magnetic element and a second receptacle for the second magnetic element.

[0028] The carrier may be adhesively bonded to the one of the bobbin assembly and support.

[0029] The magnetic assembly may be frictionally maintained on the one of the bobbin assembly and support.

[0030] The combination may further include a rotary loop taker for drawing thread on the bobbin assembly from the bobbin assembly.

[0031] The invention is further directed to the combination of a bobbin assembly and a support. The bobbin assembly has a core around which a supply of thread can be wrapped. The core has a rotational axis. The bobbin assembly is mounted to the support for rotation around the rotational axis. The bobbin assembly and support are magnetically attracted to each other with a force of a first magnitude with the bobbin assembly and support in a first state . The force resists rotation of the bobbin assembly around the rotational axis. At least one of the bobbin assembly and support is reconfigurable to cause the bobbin assembly and support to be one of a) not magnetically attracted to each other and b) magnetically attracted to each other with a force of a second magnitude, that is different than the first magnitude, with the bobbin assembly and support in a second state.

[0032] The invention is further directed to a method of controlling draw tension of thread pulled from a supply of the thread. The method includes the steps of: providing a bobbin assembly having a core around which a supply of thread can be wrapped and a rotational axis; providing a support for the bobbin assembly to allow the bobbin assembly to rotate around the rotational axis; producing a magnetic attractive force of a first magnitude between the bobbin assembly and support with the bobbin assembly and support in a first state to resist rotation of the bobbin assembly around the rotational axis; and selectively changing the support and bobbin assembly to a second state wherein one of a) the support and bobbin assembly are not attracted to each other and b) a magnetic attractive force of a second magnitude is produced between the bobbin assembly and support.

[0033] The step of producing a magnetic attractive force may involve providing first and second magnetic elements on one of the bobbin assembly and support that are attracted to a metallic portion on the other of the bobbin assembly and support.

[0034] The step of selectively changing the support and bobbin assembly to the second state may involve separating the first magnetic element from the one of the bobbin assembly and support and leaving the second magnetic element on the one of the bobbin assembly and support.

[0035] The step of producing a magnetic attractive force may involve providing a first magnetic element on one of the bobbin assembly and support that is attracted to a metallic portion on the other of the bobbin assembly and support.

[0036] In one form, the step of selectively changing the bobbin assembly and support to the second state may involve separating the first magnetic element from the one of the bobbin assembly and support.

[0037] The step of providing a first magnetic element may involve providing a first magnetic element on a carrier and attaching the carrier to the one of the bobbin assembly and support.

[0038] In one form, the step of selectively changing the bobbin assembly and support may involve tearing the carrier to allow separation of the first magnetic element from the one of the bobbin assembly and support.

[0039] The step of providing a first magnetic element may involve releasably attaching the first magnetic element to one of the bobbin assembly and support.

[0040] In one form, the step of producing a magnetic attractive force may involve providing first and second metallic elements on one of the bobbin assembly and support that are magnetically attracted to the other of the bobbin assembly and support.

[0041] In one form, the step of selectively changing the bobbin assembly and support to a second state involves separating the first metallic element from the one of the bobbin assembly and support.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 is an exploded, partially schematic, elevation view of a sewing system consisting of a bobbin assembly on a support in captive relationship between a bobbin basket and bobbin case and associated with a rotary loop taker and with a magnetic assembly, according to the present invention, incorporated so as to allow selective thread draw tension adjustment;

[0043] FIG. 2 is a perspective view of the bobbin assembly of FIG. 1 with the magnetic assembly thereon;

[0044] FIG. 3 is a cross-sectional view of the bobbin assembly taken along line 3-3 of FIG. 2;

[0045] FIG. 4 is an enlarged, fragmentary, cross-sectional view of the connection between a magnetic element on the magnetic assembly and a flange on the bobbin assembly, taken along line 4-4 of FIG. 2;

[0046] FIG. 5 is a plan view of the bobbin assembly in FIG. 2 and reconfigured by removing a plurality of the magnetic elements on the magnetic assembly;

[0047] FIG. 6 is an enlarged, plan view of the bobbin assembly in FIG. 1 with a modified form of magnetic assembly, according to the present invention, thereon;

[0048] FIG. 7 is a view as in FIG. 6 with another modified form of magnetic assembly;

[0049] FIG. 8 is a view as in FIG. 6 with another modified form of magnetic assembly;

[0050] FIG. 9 is a view as in FIG. 6 with still another modified form of magnetic assembly;

[0051] FIG. 10 is a view as in FIG. 6 with yet another modified form of magnetic assembly;

[0052] FIG. 11 is a view as in FIG. 4 and showing a modified structure for attaching a magnetic element to the bobbin assembly flange utilizing a paper carrier;

[0053] FIG. 12 is a view as in FIG. 11 wherein a solid plastic carrier is utilized in place of the paper carrier in FIG. 11;

[0054] FIG. 13 is a view as in FIG. 10 of a still further modified form of magnetic assembly, according to the present invention, and including a carrier;

[0055] FIG. 14 is a cross-sectional view of the magnetic assembly taken along line 14-14 in FIG. 13;

[0056] FIG. 15 is a plan view of one of the magnetic elements on the magnetic assembly in FIGS. 13 and 14, separated from the remainder of the magnetic assembly, and including a part of the carrier;

[0057] FIG. 16 is a cross-sectional view, corresponding to that in FIG. 4, of a modified form of flange and magnetic element according to the present invention;

[0058] FIG. 17 is an exploded view of the flange and magnetic element, as in FIG. 16, and including another form of magnetic element which can be selectively substituted for the magnetic element shown in FIG. 15;

[0059] FIG. 18 is a view as in FIG. 16 of a modified form of magnetic element which is flush with an exposed surface of the flange;

[0060] FIG. 19 is a view as in FIG. 18 wherein the flange is made from a different material than is shown in FIG. 18;

[0061] FIG. 20 is an exploded view, corresponding to that in FIG. 16, wherein connecting elements are used to releasably maintain the magnetic element attached to the flange;

[0062] FIG. 21 is an exploded, fragmentary, elevation view of a portion of a modified form of flange and magnetic element, wherein the magnetic element is screw-threaded to the flange;

[0063] FIG. 22 is a plan view of the bobbin assembly in FIG. 1 and including a metallic assembly in place of the magnetic assembly;

[0064] FIG. 23 is a fragmentary, cross-sectional view of a bobbin assembly flange and support showing a modified form of magnetic assembly cooperating with a metallic insert, according to the present invention;

[0065] FIG. 24 is a fragmentary, cross-sectional view of a magnetic assembly cooperating with a metallic portion at the bottom flange of the bobbin assembly in FIG. 1;

[0066] FIG. 25 is a view corresponding to that in FIG. 24 and showing a modified form of magnetic assembly/metallic portion;

[0067] FIGS. 26 and 27 are schematic representations of different arrangements of cooperating supports and bobbin assemblies incorporating the inventive magnetic and metallic assemblies that cooperate with metallic and magnetic portions;

[0068] FIG. 28 is an enlarged, fragmentary view of a modified form of mounting post on the support for the bobbin assembly shown in FIG. 1 and including a magnetic assembly, according to the present invention;

[0069] FIG. 29 is a cross-sectional view of the post taken along line 29-29 of FIG. 28;

[0070] FIG. 30 is an elevation view of a non-walled bobbin assembly with which the present invention can be practiced;

[0071] FIG. 31 is a schematic representation of a sewing system having a support for a bobbin assembly with an elongate element around which thread is wrapped to control thread draw tension; and

[0072] FIG. 32 is a cross-sectional view of the elongate element taken along line 32-32 of FIG. 31.

DETAILED DESCRIPTION OF THE DRAWINGS

[0073] In FIG. 1, a sewing machine assembly is shown at 10 and consists of a bobbin assembly 12 and a two-part support 14 for the bobbin assembly. The support 14 consists of a bobbin basket 16 and a cooperating bobbin case 18 which are matable to produce a receptacle at 20 for the bobbin assembly 12. The bobbin basket 16 has a cup-shaped body 22 with a post 24 projecting upwardly from a bottom wall 26. The post 24 defines the rotational axis 28 for the bobbin assembly 12, as hereinafter explained. The body 22 of the bobbin basket 16 has a peripheral wall 30 extending continuously around the central axis 28.

[0074] The bobbin case 18 has a top wall 32 from which a sleeve 34 depends in concentric relationship with the post 24. A peripheral wall 36 depends also from the top wall 32 and extends continuously around the axis 28. The sleeve 34 has a through bore 38 which continues through the top wall 32. With the bobbin basket 16 and bobbin case 18 in operative relationship, the post 24 extends fully through the sleeve 34 so that a notch 40 in the post 24 is exposed above the top wall 32. In this configuration, the peripheral wall 36 on the bobbin case 18 surrounds the peripheral wall 30 of the bobbin basket 16. A releasable latch assembly at 42 is operable to engage the notch 40 on the post 24 to prevent separation of the operatively connected bobbin basket 16 and bobbin case 18.

[0075] The bobbin assembly 12 consists of a cylindrical core 44 around which a supply of thread 46 is wrapped. The bobbin assembly 12 further has axially spaced, disk-shaped, upper and lower flanges 48, 50 attached at the axial ends of the core 44. The core 44 has a through bore 52 to receive the sleeve 34, around which the bobbin assembly 12 is journalled for rotation around the axis 28. With the bobbin basket 16 and bobbin case 18 operatively connected, the bobbin assembly 12 is captive between the bottom wall 26 of the bobbin basket 16 and the top wall 32 of the bobbin case 18.

[0076] The flanges 48, 50 have flat, facing surfaces 54, 56, respectively, which cooperatively bound a thread storage space 58. The flange 48 has a flat surface 60 facing axially oppositely to the surface 54 in a confronting relationship with a flat, downwardly facing surface 62 on the top wall 32 of the bobbin case 18. The flange 50 has a flat surface 64 facing oppositely to the surface 56 and confronting a flat, upwardly facing surface 66 on the bottom wall 26 of the bobbin basket 16.

[0077] A conventional rotary loop taker 68 is operatively associated with the joined bobbin basket 16 and bobbin case 18 and is useable in conventional manner, as well known to those skilled in this art.

[0078] In the embodiment shown in FIG. 1, the surface 62 on the wall 32 of the bobbin case 18 has at least a portion that is made from a metal material. To produce a controlled resistance to rotation of the bobbin assembly 12, a magnetic assembly at 70 is provided on the bobbin assembly flange 48. The magnetic assembly 70 and metallic portion of the surface 62 cooperate to produce a magnetic field, and preferably a magnetic attractive force, between the bobbin assembly 12 and top wall 32 of the bobbin case 18 that resists rotation of the bobbin assembly 12 relative to the bobbin case 18.

[0079] As seen additionally in FIGS. 2-4, the magnetic assembly 70 consists of a plurality of, and in this case four, discrete magnetic elements 72, 74, 76, 78, which are attached to the surface 60 on the flange 48. In this embodiment, each of the magnetic elements 72, 74, 76, 78 is flat with an arcuate shape. The shape of the magnetic elements 72, 74, 76, 78 is shown to be the same, but need not be. Exemplary magnetic element 74 has oppositely facing flat surfaces 80,82. A layer of a releasable adhesive 84 acts between the surface 82 of the magnetic element 74 and the surface 60 of the bobbin assembly flange 48 to maintain the magnetic element 74 in its operative position, as shown in each of FIGS. 2-4. Adhesives are commercially available which are capable of securely holding the magnetic element 74 upon the bobbin assembly 12, so as to follow movement thereof, yet which allow the magnetic element 74 to be peeled away from the bobbin assembly 12 under an axially applied force.

[0080] With the bobbin assembly 12 and support 14 in a first state, as shown in FIGS. 1-4, all four of the magnetic elements 72, 74, 76, 78 are held firmly in place so that the bobbin assembly 12 and support 14 are magnetically attracted to each other with a force of a first magnitude. The bobbin assembly 12 is reconfigurable by removing one or more of the magnetic elements 72, 74, 76, 78 to thereby cause the bobbin assembly 12 and support 14 to be attracted to each other with a force of a second magnitude that is less than the first magnitude. In FIG. 5, the bobbin assembly 12 is shown in a second state wherein two of the magnetic elements 74, 78 have been separated from the bobbin assembly 12.

[0081] With a full supply of thread 46 upon the bobbin assembly 12, the draw tension is lower than it is as the line supply diminishes. This is because the rotative force imparted to the bobbin assembly 12 through the thread is applied with a moment arm equal to substantially the full radius of the bobbin assembly 12. As the supply of thread 46 diminishes, the thread is drawn from a location having a considerably shorter moment arm. Accordingly, to maintain a relatively constant draw tension, the magnetic assembly can initially be configured so that the bobbin assembly 12 and support 14 are in the first state, with all of the magnetic elements 72, 74, 76, 78 fixed in place, with a full thread supply. As the supply of thread 46 is exhausted, the system operator may remove one or more of the magnetic elements 72, 74, 76, 78, at one time or at specific intervals, by peeling the same from the flange 48 to place the bobbin assembly 12 and support 14 in the second state, wherein the magnetic attractive force between the bobbin assembly 12 and support 14 is lessened. This in turn causes a reduction in the resistance to rotation of the bobbin assembly 12, and thus a reduction in the draw tension for the thread 46.

[0082] The effect of the magnetic elements 72, 74, 76, 78 on draw tension can be predetermined. The operator can thus be trained as to how to reconfigure, in this case, the bobbin assembly 12, to adjust the draw tension to maintain the same relatively constant. Through a simple step, the operator can access the magnetic elements 72, 74, 76, 78 as by removing the bobbin assembly 12, and quickly peel one or more of the magnetic elements 72, 74, 76, 78 to make this adjustment. Locating patterns 86,88 can be provided on the flange 48 to facilitate replacement of the removed magnetic elements 74, 78 in FIG. 5 to allow reusing of the bobbin assembly 12.

[0083] The disclosure of arcuate magnetic elements 72, 74, 76, 78 is intended to be exemplary only. Alternative configurations of magnetic elements are shown in FIGS. 6-10. Again, these additional embodiments are intended only to be exemplary, and not inclusive of all configurations contemplated by the invention.

[0084] In FIG. 6, five magnetic elements 92, 94, 96, 98, 99 are applied to the surface 60 of the bobbin assembly 12 in the same manner as the magnetic elements 72, 74, 76, 78 are applied, as previously described.

[0085] In FIG. 7, concentric, ring-shaped magnetic elements 100, 102, are mounted upon the surface 60 of the flange 48. The state of the bobbin assembly 12 and support 14 can be changed by separating one or both of the magnetic elements 100, 102 from the flange 48.

[0086] In FIG. 8, intermeshed, spiral, magnetic elements 104, 106 are applied to the surface 60 of the flange 48.

[0087] In FIG. 9, magnetic elements are provided in two different sized disk shapes 108, 110. In this configuration, the magnetic elements 108, 110 are alternatingly placed in an annular array on the surface 60 of the flange 48. The magnetic elements 108, 110 may be selectively separated from the flange 48 to change the state of the bobbin assembly .12 and cooperating support 14.

[0088] In FIG. 10, two different types of magnetic elements 112, 114 are provided on the surface 60 of the flange 48. The magnetic elements 112, 114 are each elongate, with the magnetic elements 112, 114 differing from each other in width. The magnetic elements 112, 114 are situated with their lengths aligned radially relative to the central axis 28. The magnetic elements 112, 114, are alternatingly placed around the axis and may be removed strategically to change the state of the bobbin assembly 12 and support 14.

[0089] The use of the adhesive 84 should not be viewed as limiting. The invention contemplates myriad ways of releasably attaching magnetic elements to the bobbin assembly 12. A description of additional embodiments will follow. Again, it should be understood that these additional embodiments are exemplary in nature only, and not intended to be limiting or inclusive of all configurations contemplated by the invention.

[0090] In FIG. 11, the exemplary magnetic element 74 in FIGS. 1-5 is shown connected as by an adhesive layer 116 to a carrier 118. In this case, the carrier 118 is a layer of paper or cloth that has weakened areas 120 coinciding with the boundary of the magnetic element 74, or closely approximating that shape. The magnetic element 74 may be permanently bonded to the carrier 118 through the adhesive layer 116. A separate adhesive layer 122 bonds the carrier 118 to the surface 60 of the flange 48. By drawing the magnetic element 74 away from the flange 48, the carrier 118 tears at the weakened areas 120 to allow the magnetic element 74 to be separated from the flange 48. The adhesive in the layer 122 may be sufficiently tenacious that less than the full thickness of the carrier will separate within the region within the weakened areas 120. Alternatively, the adhesive in the layer 122 may permit release of the entire thickness of the carrier 118 within the region bounded by the weakened areas 120.

[0091] In FIG. 12, the depicted construction differs from that in FIG. 11 only by reason of the construction of the carrier 118 from a plastic material. With this construction, the weakened areas 120 are designed to weaken the more rigid carrier 118 to an even greater extent to allow it to be torn. It is also desirable that the adhesive in the layer 122 be releasable so that excessive resistance is not encountered in separating the magnetic element 74, and underlying carrier portion, from the flange 48.

[0092] In FIGS. 13-15, a modified form of magnetic assembly is shown at 124 and consists of a carrier 126 which encases the ring-shaped magnetic elements 100, 102, as shown in FIG. 7 and described hereinabove. The carrier 126 consists of spaced layers 128, 130, each having a shape corresponding generally to the circular shape of the surface 60 on the flange 48. The layers 128, 130 are joined by concentric, annular beads of adhesive 132, 134, 136, which maintain the layers 128, 130 as a unitary structure and define separate receptacles 138, 140 for the magnetic elements 100, 102, respectively. Annular weakened areas 142, 144, 146, 148 define frangible regions which allow the layer 128 to be torn so as to selectively release one or both of the magnetic elements 100, 102 to allow separation thereof from the flange 48 to change the state of the bobbin assembly 12 and the cooperating support 114.

[0093] In FIG. 16, a magnetic element 150, intended to be representative in function of all of the magnetic elements described hereinabove and hereafter, is shown attached to a representative flange 152 by press fifting the same into an undercut receptacle 154 in the flange 152. The magnetic element 150 can be press fit into its operative position within the receptacle 154 to be selectively frictionally held, and separated therefrom, to effect reconfiguration of the flange 152. The magnetic element 150 can take virtually a limitless number of forms. As just examples, the magnetic element 150 may be in the form of a disc that extends fully around the bobbin assembly axis, or a small element that extends only a short distance around the bobbin assembly axis. The frictional holding may be accomplished through the body of the element 150 itself or through one or more separate anchoring posts 155, or through other structure.

[0094] In FIG. 17, a kit is shown in conjunction with the flange 152 and consisting of the magnetic element 150 and a magnetic element 156, which can be interchangeably mounted within the receptacle 154. The magnetic elements 150, 156 may have a different magnetic strength to change the attraction between the magnetic element 156 and a cooperating metallic position/element. The magnetic element 156 is also shown to have an optional adhesive layer 158 which augments the frictional holding force between the flange 152 and magnetic element 156.

[0095] In FIG. 18, the flange 152 is shown with a magnetic element 160 that is flush with the flange surface 162 with the magnetic element 160 within the receptacle 154. The corresponding magnetic elements 150, 156 in FIGS. 15 and 16 have a thickness that projects to above the corresponding flange surface 162.

[0096] In FIG. 19, a modification is shown for the flange 152. In FIG. 19, the corresponding flange 152′ is made from plastic material which defines a receptacle 154′ for the magnetic element 160.

[0097] In FIG. 20, the flange 152 is shown with a receptacle 154 for the magnetic element 150. Cooperating connecting elements 162, 164 are provided, one each on the flange 152 and magnetic element 150, to releasably maintain the magnetic element 15 within the receptacle 154. The connecting elements 162, 164 may be conventional hook and loop type fastener. The hook and loop type fastener can be utilized without the requirement of a receptacle. It should be understood that the use of the connecting elements 162, 164, and other structures in FIGS. 15-18, can be used with all embodiments disclosed herein.

[0098] A further modified form of magnetic element is shown in FIG. 21 at 166. The magnetic element 166 has a male threaded portion 168 to engage within a threaded female bore 170 on a flange 172.

[0099] While the magnetic elements have been described to be on the bobbin assembly 12, as shown in FIG. 22, corresponding elements 72′, 74′, 76′, 78′ on a corresponding flange 48′ may constitute a metallic assembly 172, as part of the bobbin assembly 12, to cooperate with the magnetized top wall 32 in the same manner as the top wall 32 was previously described to cooperate with the magnetic assembly 70. That is, the metal and magnetic structures are reversed but can be used in a manner corresponding to that for the structure shown in FIG. 1. The magnitude of the attractive force, and thus the state of the bobbin assembly 12 and support 14, is similarly changed by removing one or more of the metallic elements 72′, 74′, 76′, 78′, thereby producing a change in the magnitude of the attractive force between the bobbin assembly 12 and support 14.

[0100] Still further, it is not required that the magnetic portion or metallic portion, cooperating with the metallic or magnetic assemblies, be defined continuously on the wall 32. As shown in FIG. 22, an insert 174 at the surface 62 of the wall 32′, corresponding to the wall 32, can be either a metal set in a non-metal material or a metal with different magnetic properties than the metal in which it is inset. The cooperating element 176 on the flange 48′ is the complementary magnetic or metallic component to produce the magnetically attractive rotational resistance force.

[0101] While the magnetic assembly 70, metallic assembly 172, and metallic portions have been described as being on the case wall 32, and upper flange 48, all of the same structures, as heretofore described, could be incorporated to act in the same manner between the bottom wall 26 of the bobbin basket 16 and the bottom flange 50 of the bobbin assembly 12.

[0102] As just one example, as shown in FIG. 24, the bobbin basket 16′ has a magnetic/metallic element 178 embedded therein to cooperate with a metallic/magnetic element 180 that is bonded through an adhesive layer 182 to the surface 64 of the flange 50. Additional metallic/magnetic elements 180 may be provided and may be removably attached to function as those described above.

[0103] In FIG. 25, a modification is shown wherein the metallic/magnetic element 180′, corresponding to that 180 in FIG. 3, is mounted within a receptacle 184 in the flange 50. As previously noted, each of the embodiments described above, including magnetic/metallic elements cooperating between the flange 48 and wall 32, can be utilized to cooperate between the flange 50 and wall 26.

[0104] Further, as previously mentioned, any construction of the magnetic and metallic assemblies 70, 172 could be provided on either of the support 14 or bobbin assembly 12, with the complementary metallic portion/magnetic portion provided on the other of the bobbin assembly 12 and support 14. This is shown generically im FIGS. 26 and 27 and applies to each embodiment disclosed herein.

[0105] As seen in FIGS. 28 and 29, it is also contemplated that the post 24′ could be modified from that shown in FIG. 1 to incorporate a magnetic assembly at 186 consisting of magnetic elements 188, 190, 192, 194, in the form of axially extending strips, which can be press fit into complementary receptacles 196, 198, 200, 202, consecutively. With this construction, at least the bobbin assembly core 44 is made partially or entirely from a metallic material that will cause an attractive force between the magnetic elements 188, 190, 192, 194 and the bobbin assembly 12 to resist rotation of the bobbin assembly 12 about its axis 28. One, and up to all, of the magnetic elements 188, 190, 192, 194 can be removed to change the state of the support 14″ and bobbin assembly 12.

[0106] It is also contemplated that the cylindrical core 44 could be magnetized, with the magnetic elements 188, 190, 192, 194 substituted for by similarly configured metallic elements defining a metallic assembly.

[0107] As shown in FIG. 30, the invention could be incorporated into a non-walled bobbin assembly as shown at 204. The concept, as disclosed with respect to FIGS. 25 and 26, can be used to practice the invention with the non-walled bobbin assembly 204.

[0108] In FIGS. 31 and 32, a sewing system, according to the present invention, is shown at 210. The sewing system 210 corresponds to that shown in U.S. Pat. No. 6,152,057, which is incorporated herein by reference. Briefly, the sewing system 210 consists of a support 212 for a bobbin assembly 214 having a thread supply 216 thereon. The thread 216 from the. supply is wrapped spirally around an elongate member 218 on the support 212. The number of wraps around the elongate member 218 dictates the thread draw tension.

[0109] As shown in FIG. 32, the elongate member 218 consists of a core 220 with a coating 222 thereon. It has been found that by using a low friction coating, such as a Teflon® coating, draw tension increase due to the wrapping around the elongate member 218 can be kept relatively low. As a consequence, the variation in the thread draw tension is effected primarily through the magnetic/metallic assemblies 70, 172, and cooperating metallic/magnetic portions 206, 208, as shown in FIGS. 26 and 27.

[0110] The inventive concept can be employed with virtually any type of bobbin assembly and support. As just examples, the invention can be utilized with “pre-wound” bobbin assemblies, such as those made commonly from cardboard and those identified as non-walled. Pre-wound bobbin assemblies are offered with a supply of thread thereon by a manufacturer.

[0111] The invention is useable likewise with bobbin assemblies that are “post-wound”. Typically, post-wound bobbin assemblies are made from aluminum or other metal and are put in a winder to be loaded with a supply of thread at the particular facility at which sewing occurs.

[0112] The foregoing disclosure of specific embodiments is intended to be illustrative of the broad concepts comprehended by the invention.

Claims

1. In combination: a) a bobbin assembly comprising: i) a core around which a supply of thread can be wrapped, the core having a rotational axis; and ii) a first flange having first and second oppositely facing surfaces, with the first surface bounding a storage space for thread wrapped around the core; and b) a support for the bobbin assembly to allow the bobbin assembly to rotate around the rotational axis, said support comprising: a third surface facing the second surface with the bobbin assembly operatively connected to the support, the bobbin assembly and support magnetically attracted to each other with a force of a first magnitude with the bobbin assembly and support in a first state, the force resisting rotation of the bobbin assembly around the rotational axis, at least one of the bobbin assembly and support reconfigurable to cause the bobbin assembly and support to be one of a) not magnetically attracted to each other and b) magnetically attracted to each other with a force of a second magnitude, that is different than the first magnitude, with the bobbin assembly and support in a second state.

2. The combination according to claim 1 wherein there is a magnetic assembly on one of the bobbin assembly and support that is attracted to a metallic portion on the other of the bobbin assembly and support, and the bobbin assembly and support are changed from the first state into the second state by separating a part of the magnetic assembly from the one of the bobbin assembly and support.

3. The combination according to claim 1 wherein there is a metallic assembly on one of the bobbin assembly and support that is attracted to a magnetic portion on the other of the bobbin assembly and support, and the bobbin assembly and support are changed from the first state into the second state by separating a part of the metallic assembly from the one of the bobbin assembly and support.

4. The combination according to claim 2 wherein the magnetic assembly comprises a first magnetic element and with the bobbin assembly and support in the second state, the first magnetic element is separated from the one of the bobbin assembly and support.

5. The combination according to claim 2 wherein the magnetic assembly comprises first and second magnetic elements and with the bobbin assembly and support in the second state, the first magnetic element is separated from the one of the bobbin assembly and support and the second magnetic element remains on the one of the bobbin assembly and support.

6. The combination according to claim 4 wherein the first magnetic element is maintained on the one of the bobbin assembly and support by being magnetically attracted to the one of the bobbin assembly and support.

7. The combination according to claim 4 wherein the first magnetic element is maintained on the one of the bobbin assembly and support by a releasable adhesive.

8. The combination according to claim 2 wherein the magnetic assembly comprises a first magnetic element and the first magnetic element is separable from the one of the bobbin assembly and support by tearing a portion of the magnetic assembly to thereby change the bobbin assembly and support from the first state into the second state.

9. The combination according to claim 2 wherein the magnetic assembly is provided on the second flange and the metallic portion is at the third surface.

10. The combination according to claim 2 wherein the support comprises a post which guides rotation of the bobbin assembly around the rotational axis and the magnetic assembly is on the post.

11. The combination according to claim 2 wherein the magnetic assembly comprises a first magnetic element that is releasably threadably attached to the one of the bobbin assembly and support.

12. The combination according to claim 4 wherein the magnetic assembly is maintained on the one of the bobbin assembly and support by cooperating releasably connecting parts on the magnetic assembly and the one of the bobbin assembly and support.

13. The combination according to claim 2 wherein the magnetic assembly comprises first and second magnetic elements and a carrier for the first and second magnetic elements.

14. The combination according to claim 13 wherein the carrier has a weakened portion that can be torn to separate the first magnetic element from the one of the bobbin assembly and support to thereby place the bobbin assembly and support in the second state.

15. The combination according to claim 13 wherein the carrier defines a first receptacle for the first magnetic element and a second receptacle from the second magnetic element.

16. The combination according to claim 13 wherein the carrier is adhesively bonded to the one of the bobbin assembly and support.

17. The combination according to claim 16 wherein the first magnetic element is bonded to the carrier.

18. The combination according to claim 2 wherein the magnetic assembly is frictionally maintained on the one of the bobbin assembly and support

19. The combination according to claim 1 further comprising a rotary loop taken for drawing thread on the bobbin assembly from the bobbin assembly.

20. In combination: a) a bobbin assembly comprising: a core around which a supply of thread can be wrapped, the core having a rotational axis; b) a support for the bobbin assembly to allow the bobbin assembly to rotate around the rotational axis, said support comprising: the bobbin assembly and support magnetically attracted to each other with a force of a first magnitude with the bobbin assembly and support in a first state, the force resisting rotation of the bobbin assembly around the rotational axis, at least one of the bobbin assembly and support reconfigurable to cause the bobbin assembly and support to be one of a) not magnetically attracted to each other and b) magnetically attracted to each other with a force of a second magnitude, that is different than the first magnitude, with the bobbin assembly and support in a second state.

21. A method of controlling draw tension on thread pulled from a supply of the thread, the method comprising the steps of: providing a bobbin assembly comprising a core around which a supply of thread can be wrapped, the core having a rotational axis; providing a support for the bobbin assembly to allow the bobbin assembly to rotate around the rotational axis; producing a magnetic attractive force of a first magnitude between the bobbin assembly and support with the bobbin assembly and support in a first state to resist rotation of the bobbin assembly around the rotational axis; and selectively changing the support and bobbin assembly to a second state wherein one of a) the bobbin assembly and support are not attracted to each other and b) a magnetic attractive force of a second magnitude is produced between the bobbin assembly and support.

22. The method according to claim 21 wherein the step of producing a magnetic attractive force comprises providing first and second magnetic elements on one of the bobbin assembly and support that are attracted to a metallic portion on the other of the bobbin assembly and support.

23. The method according to claim 22 wherein the step of selectively changing the support and bobbin assembly to the second state comprises separating the first magnetic element from the one of the bobbin assembly and support and leaving the second magnetic element on the one of the bobbin assembly and support.

24. The method according to claim 21 wherein the step of producing a magnetic attractive force comprises providing a first magnetic element on one of the bobbin assembly and support that is attracted to a metallic portion on the other of the bobbin assembly and support.

25. The method according to claim 24 wherein the step of selectively changing the bobbin assembly and support to the second state comprises separating the first magnetic element from the one of the bobbin assembly and support.

26. The method according to claim 24 wherein the step of providing a first magnetic element comprises providing a first magnetic element on a carrier and attaching the carrier to the one of the bobbin assembly and support.

27. The method according to claim 26 wherein the step of selectively changing the bobbin assembly and support comprises tearing the carrier to allow separation of the first magnetic element from the one of the bobbin assembly and support.

28. The method according to claim 24 wherein the step of providing a first magnetic element comprises releasably attaching the first magnetic element to the one of the bobbin assembly and support.

29. The method according to claim 21 wherein the step of producing a magnetic attractive force comprises providing first and second metallic elements on one of the bobbin assembly and support that are magnetically attractive to the other of the bobbin assembly and support.

30. The method according to claim 28 wherein the step of selectively changing the bobbin assembly and support to a second state comprises separating the first metallic element from the one of the bobbin assembly and support.