Spring core made with crimpless open coils and method of making same

Abstract

A spring core for use in a bedding or seating product comprises a plurality of coil springs having unknotted end turns. The end turns are joined together with helical lacing wires. Outermost end turns of perimeter coil springs may be clipped to upper and lower border wires. In some spring cores, the coil springs are identical but oriented in different directions. In other spring cores, the coil springs are different to impart different characteristics to different sections of the spring core. The spatial relationship of the tail designs of the coil springs and helical lacing wires prevent the end turns from rotation.

Description

SPRING CORE MADE WITH CRIMPLESS OPEN COILS AND METHOD OF MAKING SAMETechnical Field Of The Invention

[0001] This invention relates generally to a spring core for a bedding or seating product and, more particularly, to a spring core made of coil springs having unknotted end turns joined together with helical lacing wires.Background Of The Invention

[0002] Traditionally, spring cores for mattresses have consisted of a plurality of spaced parallel rows of helical coil springs mounted between border wires. Coil springs adjacent the border wires have been attached to the border wires with sheet metal clips or other connections. Each of the coil springs has upper and lower end turns with a plurality of central convolutions between the upper and lower end turns. The upper and lower end turns of adjacent springs are generally connected to each other by helical lacing wires. The helical lacing wires usually extend from side-to-side or transversely joining adjacent rows of coil springs. Such helical lacing wires extend perpendicular to columns of coil springs. The outermost rows and columns of the spring core are joined to the border wires at the upper and lower end turns of the coil springs. Alternatively, the helical lacing wires may extend from end-to-end or longitudinally connecting adjacent longitudinally ending columns of coil springs.

[0003] Some spring cores are made with coil springs having knotted end turns. These coil springs are known in the industry as Bonnell coil springs. One drawback to such coil springs is that the knots at the end turns require additional wire. The more wire required to make a coil spring, the greater the expense. Asecond drawback to making Bonnell coil springs is complex machinery is required to knot the end turns. A third drawback to making Bonnell coil springs is that the wire must be thick enough to withstand the wire manipulation necessary to create the knots.

[0004] Other spring cores are made with coil springs having unknotted or open end turns. These coil springs are known in the industry as LFK coil springs. These coil springs may be made with thinner wire and on less complex machinery. In such coil springs, each end turn may be considered to have two legs joined together with a connector. The helical lacing wire captures the legs of adjacent unknotted end turns of adjacent coil springs. U.S. Patent No. 4,726,572 discloses coil springs having straight legs. U.S. Patent No. 4,781,360 discloses coil springs having legs with offsets to prevent movement of the end turns within the helical lacing wires. Such movement of the end turns causes misalignment of the coil springs so they fail to line up in straight rows and columns. Such misalignment moves the central spring axis of some coil springs from their desirable vertical positions, causing misalignment. U.S. Patent No. 5,584,083 seeks to eliminate this misalignment problem by having curved legs at the end turns of the coil springs. However, incorporating curves into the end turns of the coil springs requires more metal for the coil spring which increases the cost of manufacture and complexity of manufacture.

[0005] The present invention is a coil spring with unknotted end turns which may be easily manipulated into a desired position relative to the helical lacing wire which maintains the position of the end turn of the coil spring.

[0006] The coil spring is made of high tensile strength pocket wire, as opposed to low tensile strength wire, which reduces the expense of the wire.

[0007] One of the limitations of such spring cores is that the height of the spring core is limited by the strength of the wire. A spring core which is too tall may tilt or fail to function properly if subjected to too great a load.

[0008] The present invention allows for a spring core to made having round unknotted upper and lower end turns which stay inside the helical lacing wires after assembly. In addition, the present invention allows for the coil springs to made of a high tensile strength wire, increasing the height of the spring cores which may be manufactured.

[0009] The present invention also may be manufactured on a less complex machine which leads to higher efficiency and less operator costs than heretofore known machines.

[0010] The machine of the present invention also is able to create a zoned spring core having areas of different firmness.

[0011] The machine of the present invention allows for easier heat treatment of the coil springs, while having the same advantages as other coil springs having the same desired characteristics.Summary Of The Invention

[0012] In one aspect, a bedding or seating product comprises a spring core comprising upper and lower border wires and a plurality of identically configured coil springs. Each coil spring is made of a single piece of wire having a central spiral portion defining a central spring axis and terminating at opposed ends with unknotted upper and lower end turns. Each of the upper and lower end turns is preferably, but not always, circular other than a kinked tail portion terminating in a free end. In someembodiments, the upper and lower end turns are disposed in planes substantially perpendicular to the spring axis.

[0013] The coil springs are arranged in side-by-side rows and columns and are connected with each other at the upper and lower end turns by helical lacing wires. Opposed portions of adjacent end turns are contained within one of the helical lacing wires, the kinked tail portion of one of the end turns being outside the helical lacing wire.

[0014] In a second aspect, a bedding or seating product comprises a spring core, padding and a covering. The spring core comprises upper and lower border wires and a plurality of identically configured coil springs. Each coil spring is made of a single piece of wire having a central spiral portion defining a central spring axis and terminating at opposed ends with unknotted upper and lower end turns. Each of the upper and lower end turns is preferably, but not always, circular other than a linear tail portion terminating in a free end. In some embodiments, the upper and lower end turns are disposed in planes substantially perpendicular to the spring axis.

[0015] The coil springs are arranged in side-by-side rows and columns and are connected with each other at the upper and lower end turns by helical lacing wires. The coil springs are all oriented the same direction except the coil springs of one outermost column. The linear tail portion of each end turn of each coil spring is contained within one of the helical lacing wires, except for the coil springs of one outermost row and a corner coil spring of an opposite row. Each linear tail portion of one of these coil springs is clipped to one of the border wires.

[0016] In a third aspect, a bedding or seating product comprises a spring core, comprising upper and lower border wires and a plurality of identically configured coil springs. Each coil spring is made of a single piece of wire having a central spiralportion defining a central spring axis and terminating at opposed ends with unknotted upper and lower end turns. Each of the upper and lower end turns is preferably, but not always, circular other than a linear tail portion terminating in a free end. In some embodiments, the upper and lower end turns are disposed in planes substantially perpendicular to the spring axis.

[0017] The coil springs are arranged in side-by-side rows and columns. They are connected with each other at the upper and lower end turns by helical lacing wires. Opposed portions of adjacent end turns are contained within one of the helical lacing wires. The linear tail portion of each of the end turns is inside one of the helical lacing wires, except for the tail portions of the end turns of some of the perimeter coil springs.

[0018] In a fourth aspect, a bedding or seating product comprises a spring core. The spring core comprises upper and lower border wires and a plurality of identically configured coil springs. Each coil spring is made of a single piece of wire having a central spiral portion defining a central spring axis and terminating at opposed ends with unknotted upper and lower end turns. Each of the upper and lower end turns is preferably, but not always, circular other than a kinked tail portion terminating in a free end. In some embodiments, the upper and lower end turns are disposed in planes substantially perpendicular to the spring axis.

[0019] The coil springs are arranged in side-by-side rows and columns. They are connected with each other at the upper and lower end turns by helical lacing wires. Opposed portions of adjacent end turns are contained within one of the helical lacing wires. The kinked tail portion of each of the end turns has passed through one of the helical lacing wires, except for the kinked tail portions of the end turns of some of the perimeter coil springs.

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the summary of the invention given above, and the detailed description of the drawings given below, explain the principles of the present invention.Brief Description Of The Drawings

[0021] Fig. 1 is a top view of a bedding or seating product having a spring core made in accordance with the principles of the present invention.

[0022] Fig. 2 is a perspective view of a coil spring used in the spring core of Fig. 1.

[0023] Fig. 3 is a view taken along the line 3-3 of Fig. 2.

[0024] Fig. 4 is a view taken along the line 4-4 of Fig. 2.

[0025] Fig. 5 is an enlarged top view of a portion of the spring core of Fig. 1.

[0026] Fig. 6 is a perspective view of a portion of the spring core of Fig. 1.

[0027] Fig. 7 is a top view of a bedding or seating product having another spring core made in accordance with another aspect of the present invention.

[0028] Fig. 8 is a perspective view of a coil spring used in the spring core of Fig. 7.

[0029] Fig. 9 is a view taken along the line 9-9 of Fig. 8.

[0030] Fig. 10 is a view taken along the line 10-10 of Fig. 8.

[0031] Fig. 11 is an enlarged top view of a portion of the spring core of Fig. 7.

[0032] Fig. 12 is a perspective view of a portion of the spring core of Fig. 7.

[0033] Fig. 13 is a schematic view of a machine used to make the spring cores disclosed herein.

[0034] Fig. 14 is an enlarged top view of a coil spring which shows some differences between the two coil springs disclosed herein.Detailed Description Of The Invention

[0035] Referring to Fig. 1 , there is illustrated a bedding or searing product in the form of a mattress 10 made in accordance with one aspect of the present invention. Although a mattress 10 is illustrated, any aspect of the present invention may be used to construct any bedding or seating product. The mattress 10 comprises a spring core or spring assembly 12, padding 14 located on top of an upper surface of the mattress 10 and an upholstered covering 18 surrounding the spring core 12 and padding 14.

[0036] As shown in Fig. 6, the spring core 12 has a generally planar upper surface 16 located generally in a plane P1 and a generally planar lower surface 20 located generally in a plane P2. The distance between the upper and lower surfaces 16, 20 of spring core 12 defines the height H of the spring core 12. Referring to Fig.1 , the mattress 10 has a longitudinal dimension or length L defined as the distance between opposed end surfaces 22 and a transverse dimension or width W defined as the distance between opposed side surfaces 24.

[0037] As best illustrated in Figs. 1 , 2 and 6, the spring core 12 comprises a plurality of aligned identical coil springs 26 made in accordance with the present invention. One of the coil springs 26 is illustrated in detail in Figs. 2, 3 and 4.Referring to Fig. 1, the coil springs 26 are arranged in transversely extending rows 28 and longitudinally extending columns 30. Helical lacing wires 32 are shown extending transversely and located generally in the upper and lower surfaces 16, 20 of the spring core 12. The helical lacing wires 32 join adjacent rows 28 of coil springs26 together in a manner described below. The coil springs 26 are of the same hand; the wire extends in a clockwise direction as the wire moves down the coil spring (from top to bottom). See Fig. 1.

[0038] In some embodiments not shown, the helical lacing wires may extend longitudinally.

[0039] As illustrated in Figs. 1 and 6, the coil springs 26 are oriented the same direction within the spring core 12 with the exception of the coil springs 26 of the outermost column 31. The coil springs 26 of the outermost column 31 are rotated 180 degrees about the central spring axes 34 of the coil springs 26 relative to the coil springs 26 within columns 30. This rotation of the coil springs 26 enables the coil springs 26 around the perimeter of the mattress 10 to be clipped or otherwise secured to an upper border wire 36 and lower border wire (not shown) with clips 38. In any of the embodiments shown or described herein, one or both of the border wires may be omitted.

[0040] Figs. 2, 3 and 4 illustrate one of the coil springs 26 of the first embodiment described herein. Figs. 2, 3 and 4 illustrate coil spring 26 in a relaxed or uncompressed condition. Coil spring 26 is made of a single piece of wire having a central spiral portion 40 made up of a plurality of consecutive helical loops or revolutions 42 defining a central spring axis 34. Although the revolutions of the central spiral portion 40 are illustrated having the same diameter, they may have different diameters. The coil spring 26 has unknotted upper end turn 44 disposed substantially in a plane P3 and an unknotted lower end turn 46 disposed substantially in a plane P4. The planes P3 and P4 are substantially perpendicular to the central spring axis 34, in some embodiments. In other embodiments, the upper and lower end turns may be angled or slanted relative to a horizontal orientation.

[0041] As best shown in Fig. 3, unknotted upper end turn 44 has a diameter D1 which is larger than the diameter D2 of the revolutions 42 of the central spiral portion 40. At location 48 of the unknotted upper end turn 44, a kinked tail portion 50 begins. The kinked tail portion 50 terminates in a free end 52.

[0042] As best shown in Fig. 4, unknotted lower end turn 46 has a diameter D3 which is larger than the diameter D2 of the revolutions 42 of the central spiral portion 40. At location 54 of the unknotted lower end turn 46, a kinked tail portion 56 begins. The kinked tail portion 56 terminates in a free end 58. The diameter D3 may be the same diameter as the diameter of the upper end turn, in some embodiments.

[0043] As best shown in Figs. 2, 3 and 4, the kinked tail portion 50 of the upper end turn 44 and the kinked tail portion 56 of the lower end turn 46 are on opposite sides of the central spring axis 34. Although the coil spring 26 is shown having a certain number of revolutions 42 of the central spiral portion 40, the drawings are not intended to be limiting. The coil spring 26 may have any number of revolutions 42 of the central spiral portion 40 to achieve a desired height.

[0044] Fig. 5 illustrates the spatial relationship between the upper end turns 44 of the coil springs 26 and the helical lacing wires 32. More specifically, a curved portion 60 of an upper end turn 44 is captured within the convolutions of one of the helical lacing wires 32 along with an opposed curved portion 62 of the upper end turn 44 proximate the kinked tail portion 50. The beginning 48 of the kinked tail portion 50 is located just outside the helical lacing wire 32. The kinked tail portion 50 of each upper end turn 44 is entirely outside the convolutions of the helical lacing wire 32. The shape of the kinked tail portion 50 keeps adjacent upper end turns 44 aligned properly to ensure the coil spring axes 34. Although not shown, the lower end turns are oriented in the same fashion.

[0045] Figs. 7-12 illustrate another embodiment of mattress 10a. The mattress 10a comprises a spring core 12a, padding 14 located on top of an upper surface of the mattress 10a and an upholstered covering 18 surrounding the spring core 12a and padding 14.

[0046] As shown in Fig. 12, the spring core 12a has a generally planar upper surface 16 located generally in a plane P5 and a generally planar lower surface 20 located generally in a plane P6. The distance between the upper and lower surfaces 16, 20 of the spring core 12a defines the height H of the spring core 12a. Referring to Fig. 7, the mattress 10a has a longitudinal dimension or length L defined as the distance between opposed end surfaces 22 and a transverse dimension or width W defined as the distance between opposed side surfaces 24.

[0047] As best illustrated in Figs. 7, 11 and 12, the spring core 12a comprises a plurality of aligned identical coil springs 26a made in accordance with the present invention. One of the coil springs 26a is illustrated in detail in Figs. 8, 9 and 10.Referring to Fig. 7, the coil springs 26a are arranged in transversely extending rows 28 and longitudinally extending columns 30. Helical lacing wires 32 are shown extending transversely and located generally in the upper and lower surfaces 16, 20 of the spring core 12a. The helical lacing wires 32 join adjacent rows 28 of coil springs 26a together in a manner described below. The coil springs 26a are of the same hand; the wire extends in a clockwise direction as the wire moves down the coil spring (from top to bottom). See Fig. 8.

[0048] As illustrated in Figs. 7 and 11 , the coil springs 26a are oriented the same direction within the spring core 12 with the exception of the coil springs 26a of the outermost column 31. The coil springs 26a of the outermost column 31 are rotated 180 degrees about the central spring axes 34 of the coil springs 26a relative - io-to the coil springs 26a within columns 30. This rotation of the coil springs 26a enables the coil springs 26a around the perimeter of the mattress 10a to be clipped or otherwise secured to an upper border wire 36 and lower border wire 37 with clips 38.

[0049] Figs. 8, 9 and 10 illustrate one of the coil springs 26a of the second embodiment described herein. Figs. 8, 9 and 10 illustrate coil spring 26a in a relaxed or uncompressed condition. Coil spring 26a is made of a single piece of wire having a central spiral portion 40 made up of a plurality of consecutive helical loops or revolutions 42 defining a central spring axis 34. Although the revolutions of the central spiral portion 40 are illustrated having the same diameter, they may have different diameters. The coil spring 26a has unknotted upper end turn 44a disposed substantially in a plane P7 and an unknotted lower end turn 46a disposed substantially in a plane P8. The planes P7 and P8 are substantially perpendicular to the central spring axis 34 in some embodiments.

[0050] As best shown in Fig. 8, unknotted upper end turn 44a has a diameter D3 which is larger than the diameter D2 of the revolutions 42 of the central spiral portion 40. At location 48a of the unknotted upper end turn 44a, a linear tail portion 51 begins. The linear tail portion 51 terminates in a free end 53.

[0051] As best shown in Fig. 9, unknotted lower end turn 46a has a diameter D1 which is larger than the diameter D2 of the revolutions 42 of the central spiral portion 40. At location 54a of the unknotted lower end turn 46a, a linear tail portion 57 begins. The linear tail portion 57 terminates in a free end 59.

[0052] Fig. 11 illustrates the spatial relationship between the upper end turns 44a of the coil springs 26a and the helical lacing wires 32. More specifically, a curved portion 60 of the upper end turn 44a is captured within the convolutions ofone of the helical lacing wires 32 along with a linear tail portion 51 of the upper end turn 44a. The beginning 48a of the linear tail portion 51 is located inside the helical lacing wire 32. The linear tail portion 51 of each upper end turn 44a is entirely inside the convolutions of the helical lacing wire 32. The shape of the linear tail portion 51 keeps adjacent upper end turns 44a aligned properly to ensure the coil spring axes. Although not shown, the lower end turns are oriented in the same fashion.

[0053] As best shown in Figs. 8, 9 and 10, the linear tail portion 51 of the upper end turn 44a and the linear tail portion 57 of the lower end turn 46a are on opposite sides of the central spring axis 34 and extend the same direction. Although the coil spring 26a is shown having a certain number of revolutions 42 of the central spiral portion 40, the drawings are not intended to be limiting. The coil spring 26a may have any number of revolutions 42 of the central spiral portion 40 to achieve a desired height.

[0054] Fig. 13 is a schematic view of a machine for making the spring cores 12, 12a or any combination thereof. The machine 100 comprises a housing 102 inside which is coiler 104 which accepts wire from a wire supply 106 after the wire has been heat treated at location 108. After the coil springs have been made they are discarded by a coil spring ejector 110 onto a coil transfer mechanism 112 which transfers the coil springs into an assembler 114 which assembles the spring core. The entire process is controlled by a controller 116.

[0055] Fig. 14 shows both unknotted upper end turns 44, 44a overlapped. Although not shown, the unknotted lower end turns 46, 46a are designed in the same manner. For purposes of this drawings, the end turn is divided into three sections: S1 , S2 and S3. S1 is preferably formed as a curve. Its radius is of a size to be caught inside one of the helical lacing wires. Alternatively, S1 may be straight. S2may be straight and inside one of the helical lacing wires or curved in which case it is outside one of the helical lacing wires. S2’s length may be up to 200 mm. The main function of S2 is to protect the end turn from turning.

[0056] Although not shown, a spring core may be made of both coil springs 26 and 26a. In one spring core, one or more sections may be made with coil springs 26 and at least one other section may be made with coil springs 26a. Such a spring core may be posturized into regions of different firmness.

[0057] The various embodiments of the invention shown and described are merely for illustrative purposes only, as the drawings and the description are not intended to restrict or limit in any way the scope of the claims. Those skilled in the art will appreciate various changes, modifications, and improvements which can be made to the invention without departing from the spirit or scope thereof. The invention in its broader aspects is therefore not limited to the specific details and representative apparatus and methods shown and described. Departures may therefore be made from such details without departing from the spirit or scope of the general inventive concept. The invention resides in each individual feature described herein, alone, and in all combinations of any and all of those features. Accordingly, the scope of the invention shall be limited only by the following claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A bedding or seating product comprising:a spring core comprising upper and lower border wires and a plurality of identically configured coil springs, each coil spring being made of a single piece of wire having a central spiral portion defining a central spring axis and terminating at opposed ends with unknotted upper and lower end turns, each of the upper and lower end turns being circular other than a kinked tail portion terminating in a free end,the coil springs being arranged in side-by-side rows and columns and being connected with each other at the upper and lower end turns by helical lacing wires, opposed portions of adjacent end turns being contained within one of the helical lacing wires, the kinked tail portion of one of the end turns being outside the helical lacing wire.

2. The product of claim 1 , wherein the upper and lower end turns are disposed in planes substantially perpendicular to the spring axis.

3. The product of claim 1 , wherein the free end is outside the helical lacing wire.

4. The product of claim 1 , wherein all of the coil springs are oriented the same except for the coil springs of one outermost column.

5. The product of claim 1 , wherein the central spiral portion of each spring comprises circular central convolutions of a diameter less than the diameter of the end turns.

6. The product of claim 1 wherein the coil springs are made of high tensile strength wire.

7. A bedding or seating product comprising:a spring core comprising upper and lower border wires and a plurality of identically configured coil springs, each coil spring being made of a single piece of wire having a central spiral portion defining a central spring axis and terminating at opposed ends with unknotted upper and lower end turns, each of the upper and lower end turns being circular other than a linear tail portion terminating in a free end,the coil springs being arranged in side-by-side rows and columns and being connected with each other at the upper and lower end turns by helical lacing wires, the coil springs being oriented the same direction, except for the coil springs of one outermost column.

8. The product of claim 7, wherein the upper and lower end turns are disposed in planes substantially perpendicular to the spring axis.

9. The product of claim 7, wherein the free end of each end turn of each coil spring is inside one of the helical lacing wires, except for the coil springs of one outermost column.

10. The product of claim 7, wherein multiple turns of one of the helical lacing wires capture the linear tail portion of each of the end turns, except for the end turnsof the coil springs of one outermost row and the end turns of a corner coil spring of an opposite row.

11. The product of claim 1 , wherein the central spiral portion of each spring comprises circular central convolutions of a diameter less than the diameter of the end turns.

12. The product of claim 1 wherein the coil springs are made of high tensile strength wire.

13. A bedding or seating product comprising:a spring core comprising upper and lower border wires and a plurality of identically configured coil springs, each coil spring being made of a single piece of wire having a central spiral portion defining a central spring axis and terminating at opposed ends with unknotted upper and lower end turns, each of the upper and lower end turns being circular other than a linear tail portion terminating in a free end,the coil springs being arranged in side-by-side rows and columns and being connected with each other at the upper and lower end turns by helical lacing wires, opposed portions of adjacent end turns being contained within one of the helical lacing wires, the linear tail portion of each of the end turns being inside one of the helical lacing wires except for the tail portions of the end turns of some of the perimeter coil springs.

14. The product of claim 13 wherein the coil springs are made of high tensile strength wire.

15. The product of claim 13, wherein the central spiral portion of each spring comprises circular central convolutions of a diameter less than the diameter of the end turns.

16. The product of claim 13, further comprising padding and a covering encasing the padding and spring core.

17. The product of claim 13, wherein the linear tail portions of the end turns of some of the perimeter coil springs are secured to the border wires.

18. The product of claim 13, wherein the linear tail portions of the end turns of some of the perimeter coil springs are clipped to the border wires.

19. A bedding or seating product comprising:a spring core comprising upper and lower border wires and a plurality of identically configured coil springs, each coil spring being made of a single piece of wire having a central spiral portion defining a central spring axis and terminating at opposed ends with unknotted upper and lower end turns, each of the upper and lower end turns being circular other than a kinked tail portion terminating in a free end,the coil springs being arranged in side-by-side rows and columns and being connected with each other at the upper and lower end turns by helical lacing wires,opposed portions of adjacent end turns being contained within one of the helical lacing wires, the kinked tail portion of each of the end turns having passed through one of the helical lacing wires except for the kinked tail portions of the end turns of some of the perimeter coil springs.

20. The product of claim 19, wherein the kinked tail portions of the end turns of some of the perimeter coil springs are clipped to the border wires.- 18 -

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