Patent Grant
9687905
Sinuous wire springs have a long history of being used in furniture items, such as various seating units. They are known in the industry to serve various functions with a relatively minimum amount of wire, which can translate into lower costs. A sinuous wire spring is made up of a series of parallel “bars” connected by a series of semi-circular “loops” to form a serpentine-like configuration. Often a pre-determined number of bars and loops are used to create a sinuous spring of a specific length. The two ends of the sinuous spring are typically terminated in a “safety end”, to keep the spring from slipping out of its rail attachment clip, or in a specialty end designed for attachment to metal rails, for instance.
Sinuous springs might be fabricated using various techniques. For example, the loops might be bent, stamped, or formed into the wire. Commonly, once the wire is formed into a sinuous configuration, the entire spring is further formed into a circular shape of a given radius, and put through a stress relief process. Many options of gauge of wire and finished length of the spring are available to suit various applications.
Sinuous springs are typically installed in a wood or metal frame by pulling the spring between the front and back rails of the frame, creating tension on the spring due to the un-coiling of the circular shape, and some stretching of the overall spring. The performance of the sinuous spring is primarily due to the torsion action of the flat bars of the spring. Sinuous springs are typically unitized in the seat frame by connecting them together by means such as metal hooks, or by clipping one or more pieces of paper or plastic covered “stake wire” to the flat bars of the sinuous, across the width of the seat, so that the individual sinuous will be tied together to act in a more unified fashion.
In some arced springs, when the spring is pulled between the rails, the arc of the spring is never pulled completely flat, creating a crown to the sinuous spring that adds to the ride and liveliness of the seat, as well as to the durability. But the radius of the spring can be increased in the stress relief process, in which case the crown of the seat is reduced. When the spring is manufactured flat, or very nearly flat, then the crown of the seat is eliminated. Reducing the radius or providing a flat spring can reduce the performance of the seat, but are sometimes chosen because the springs can be easier to handle and install.
An embodiment of the present invention is directed to a sinuous spring having both parallel bars and non-parallel bars. For example, the spring might include a middle segment having parallel bars and opposing end spring segments that include non-parallel bars.
Another embodiment of the present invention is directed to a wire-fabricating apparatus that includes a wire-forming mechanism and a length-adjusting mechanism. The wire-forming mechanism includes one or more sets of wire-forming dies that receive a continuously fed wire and that form the wire into a wire-shape configuration (e.g., sinuous-shape configuration). The length-adjusting mechanism includes a set of grooved wheels that receive the formed wire in the grooves and rotate to stretch or compress the formed wire. For example, the grooved wheels might be rotated at variable speeds that are programmed to stretch the formed wire, or the wheels might be rotated at a similar speed with an angular offset in respective timing.
Another embodiment of the present invention includes a method of fabricating a wire spring, including feeding a wire between two sets of complementary wire-forming dies. The wire is formed into a wire-shape configuration by moving one or more of the complementary wire-forming dies along respective tracks and causing the two sets of complementary wire-forming dies to interlock. The formed wire is then fed below an upper set of one or more grooved wheels and/or above a lower set of one or more grooved wheels, the formed wire being received in one or more grooves of the grooved wheels. In addition, the formed wire is stretched or compressed by controlling the speed or angular offset of the two or more wheels included in the upper set, the lower set, or a combination thereof, while the wire is received in the one or more grooves.
Embodiments of the invention are defined by the claims below, not this summary. A high-level overview of various aspects of the invention is provided here to introduce a selection of concepts that are further described below in the detailed-description section. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in isolation to determine the scope of the claimed subject matter.
Illustrative embodiments of the present invention are described in detail below with reference to the attached drawing figures, which are incorporated herein by reference, wherein:
The subject matter of embodiments of the present invention is described with specificity herein to meet statutory requirements. But the description itself is not intended to necessarily limit the scope of claims. Rather, the claimed subject matter might be embodied in other ways to include different elements or combinations of elements similar to the ones described in this document, in conjunction with other present or future technologies.
Referring briefly to
The spring 600 might be fabricated using various techniques, and illustrative components of a spring-fabricating apparatus are depicted in
Referring now to
In the figures, the wire-forming mechanism 112 includes a wire-forming chain 118 mounted on a track 120. In addition, the wire-forming chain 118 includes a set of wire-forming dies (e.g., 122 and 130). Each die includes a wire-shape configuration. The wire-forming chain 118 is moved in the direction of arrow 121 (i.e., clockwise in
In one embodiment, the wire-forming mechanism 112 includes another wire-forming chain 124 having another set of wire-forming dies 126 that is complementary to, and aligned with, the set of wire-forming dies 122. The wire-forming chain 124 and dies 126 are moved in the direction of arrow 125 (i.e., counterclockwise in
In
In one embodiment, the dies 122 and 126 interlock to form a wire into a sinuous spring 600 depicted in
In one embodiment, a die 130 or 132 in one portion of the set of dies is substantially similar to a die 122 or 126 (respectively) in another set of dies. That is, when a uniform spring is desired, all of the dies on a chain might create a substantially identical form. In an alternative embodiment, the die 130 or 132 might be different than the dies 122 or 126, such that a variable spring is formed. In other words, in some instances a variable loop product is desired that includes loops and bars having different configurations within the same spring. As such, dies within the same chain might have different configurations, which allow a formed spring to include variable loops and bars.
In another embodiment, it is desirable to modify a length of all of, or part of, a sinuous spring after it has been formed. As such, a sinuous spring can be fed into the length-adjustment mechanism 114 to compress or stretch the spring. The length-adjustment mechanism includes a series of grooved wheels 140, 142, and 144. In
The wheels are positioned in a substantially similar plane, as depicted in
Although the figures depict two top wheels and one bottom wheel, the top set might include one wheel or more than two wheels, and the bottom set might include a plurality of wheels. In addition, the length-adjustment mechanism might include only top wheels or only bottom wheels.
In one embodiment, the grooves of each wheel are timed to correspond with a pattern created by the dies of the wire-forming mechanism 112, such as a sinuous-shape pattern. For example, in
In a further embodiment, each wheel is coupled to a drive mechanism 152, 154, and 156, such as a servo motor. The drive mechanism might include variable speeds in which the respective speed of each of wheels 140, 142, and 144 might be independently controllable, such that the wheels are rotatable at different speeds. Or the drive mechanisms might include a respective single speed.
The length-adjustment mechanism 114 might be operated in various manners to stretch or compress a formed spring. In one embodiment, when a sinuous-shaped spring is positioned or fed in the grooves of the wheels, such as depicted in
Once the formed wire is fed from the length-adjusting mechanism, the formed wire might be acted upon by various other machines or mechanism. For example, in one embodiment, the formed wire is fed into an accumulator, which serves as a buffer before the formed wire is passed to another mechanism. For example, the accumulator might provide a buffer before the formed wire is fed to a cut-off press. In this instance, the feed of the formed wire might be stopped so that the formed wire can be cut to a desired length and the ends formed into safety ends. In one embodiment, the forming apparatus 112 continues to run even when the feed for the formed wire is stopped to allow for cutting and bending. As such, the controls for the various devices, such as the forming apparatus 112, length-adjustment device 114, and accumulator must be appropriately configured to reduce the likelihood that the accumulator will be over-filled. In one embodiment, the speeds and feeds are manipulated through the operator interface to achieve a smooth-flowing loop of accumulated sinuous wire inside the accumulator, which allows the forming mechanisms to run constantly while the cut-off-press feed runs intermittently.
Accordingly, the formed wire might be fed into a cut-off press, which cuts the formed wire to a desired length an forms the ends of the wire (e.g., safety ends). After being cut to a desired length, the formed wire might be roll-formed to include a desired curvature. That is, the formed wire might be forced over a mandrel to create an arc in the formed spring. An example of one type of roll-forming device is described by U.S. Pat. No. 7,954,349, and a similar device might also be used in combination with the forming apparatus 112 and length-adjustment apparatus 114. For instance, a belt might be used to force the formed wire over the mandrel, and the belt might include various elements. In one embodiment, the belt includes a combination of a cog-type drive belt and an abrasion-resistant conveyor belt, which are laminated back-to-back. The cog-type drive belt is used to drive the belt, and the abrasion-resistant conveyor belt is used to engage and form the wire around the mandrel. These various mechanisms and devices can be configured in various manners to create a spring having desired specifications.
Once a spring has been roll-formed to include a desired curvature, the spring is stacked together with a series of other springs for distribution and eventual assembly. Stacking and handling might be facilitated in various manners. For instance, a mechanism similar to the nesting-stacking machine described in U.S. Pat. No. 7,954,349 is utilized, and multiple machines might be used depending on how fast the fabrication process is executed. As such, in one embodiment, the fabrication line includes a diverter chute, which directs each spring to a respective nesting-stacking machine. In another aspect, the roll forming and stacking could be separate into different portions of the overall process.
Turning now to
A sinuous spring 10 is depicted that includes a middle segment 12, a first end segment 14, and a second end segment 16. The sinuous spring 10 includes a series of bars 18-37 that are connected by a series of semi-circular loops 38-56. The middle segment includes a series of bars 25-30; the first end segment 14 includes a series of bars 18-24; and the second end segment includes a series of bars 31-37. The bars 25-30 of the middle segment are substantially parallel to one another, whereas the bars 18-24 are angled with respect to one another and the bars 31-37 are also angled.
Each of the bars in the end segments are oriented at an angle 58, 60, or 62 respective to an adjacent bar. For example, the bars 23 and 24 are arranged at angle 58 with respect to one another. In
In one embodiment, the angle 58 is about 30 degrees, and the angles 60 and 62 are about 15 degrees. These angles are modifiable to achieve desired spring characteristics. For example, increasing the angle 58 might reduce the amount of wire used to construct a spring having a given overall length, thereby reducing materials costs to produce the spring 10, but might also modify the spring performance. In contrast, decreasing the angle 58 might increase both the amount of wire used to construct the spring and the materials costs, but might also enhance the spring performance.
In
In
When determining a configuration of the spring 10, one measurement includes a distance between reference lines. For example,
Another element that contributes to the configuration of the spring includes the radius of the loops. For example, reference numeral 90 points to some loops 38, 44, and 46 that have a similar radius, and in one embodiment, the radius of these loops is about 0.676 inches. The radius of other loops 45, 47, 48, 49, 50, and 56 would be substantially similar. In addition, reference numeral 91 identifies another loop 40, which has a radius that is bigger than the loops identified by reference numeral 90. In one embodiment, loops 39-43 and 51-55 have a radius of about 0.716 inches.
The sinuous spring 10 might be referred to as a varied-loop spring based on the different loop configurations included within the same spring. The varied-loop spring might have slightly higher rail strain, and create a slightly firmer seat, than a consistent-loop spring (non-varied-loop spring) if both springs are produced in the same gauge. In one embodiment, the varied-loop spring is constructed of a wire having a lighter gauge, which creates a firmness and rail strain substantially similar to the non-varied-loop spring. For instance, the gauge 98 might be about 8.75 GA.
The spring 10 might be constructed using various methods. For example, the spring could be formed having consistent loops from one end to the other, and the two end portions 14 and 16 could be stretched. In an alternative embodiment, the spring is formed having varied loops by using a variable-loop die. In addition, after the varied-loop spring 10 is constructed, the spring 10 might be stress relieved in the flat condition, or any amount of desired arc could be added to the spring before stress relief.
Referring now to
Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the scope of the claims below. Embodiments of our technology have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to readers of this disclosure after and because of reading it. Alternative means of implementing the aforementioned can be completed without departing from the scope of the claims below. Certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2645252 | Norman | Jul 1953 | A |
| 2778385 | Gier, Jr. | Jan 1957 | A |
| 2874731 | Smith | Feb 1959 | A |
| 3071168 | Surletta | Jan 1963 | A |
| Entry |
|---|
| International Search Report with Written Opinion dated Nov. 4, 2015 in Application No. PCT/US2015/045700, 10 pages. |
| International Preliminary Report on Patentability dated Mar. 9, 2017 in International Application No. PCT/US2015/045700, 6 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20160059299 A1 | Mar 2016 | US |
