IMPROVED ADHESIVE BONDING OF STRINGS OF POCKETED COIL SPRINGS

Abstract: A method and system for manufacturing a spring core (10) by adhesively bonding strings (12) of pocketed coil springs (14) together utilizes a moving adhesive applicator (28) for depositing adhesive onto a moving string (12) of pocketed coil springs (14). Subsequently, individual strings (12) are adhesively bonded to similar strings (12) to form the spring core (10) of pocketed coil springs (14). The moving applicator (28) may take one of any number of various embodiments which include reciprocating movement, rotational movement, pivotal movement and/or linear translational movement for spraying a pattern of adhesive (22) onto the moving string (12) of pocketed coil springs (14).

Description: IMPROVED ADHESIVE BONDING OF STRINGS OF POCKETED COIL SPRINGS This is a continuation-in-part of U.S. Patent Application Serial No. 09/1 53,445, filed September 1 5, 1 998, assigned to the assignee of this invention and hereby incorporated by reference in its entirety. Background of the Invention This invention relates generally to the construction of spring assemblies or the like. More particularly, it relates to the manufacture of spring cores of strings of pocketed coil springs for use in mattresses, seat cushions or the like. Mattress spring core construction over the years has been a continuously improving art with advancement in materials and machine technology. A well known form of spring core construction is known as a Marshall spring construction wherein metal coil springs are encapsulated in individual pockets of fabric and formed as elongate or continuous strings of pocketed coil springs. In an early form, these strings of coil springs were manufactured by folding an elongate piece of fabric in half lengthwise to form two plies of fabric and stitching transverse and longitudinal seams to join the plies of fabric to define pockets in which the springs were enveloped. Recently, improvements in spring core constructions have included the use of fabrics which are thermally or ultrasonically weldable to themselves. By using such welding techniques, these fabrics have been used advantageously on a mass production basis to more efficiently manufacture strings of individually pocketed coil springs wherein transverse and longitudinal welds replace stitching to form pockets encapsulating the springs. The manufacture of strings of pocketed coil springs with a single spring in each pocket is well known in the art and, for example, such machines and systems are commercially available from Spuhl AG in Switzerland. Examples of such machines include the Spϋhl TF 90, 1 90 and 290 series machines. Another known system for pocketing coil springs is disclosed in U.S. Patent No. 4,439,977 which is hereby incorporated by reference in its entirety. Once strings of pocketed coil springs are manufactured, they may be assembled to form a spring core construction for a mattress, cushion or the like by a variety of methods. For example, multiple or continuous strings may be arranged in a row pattern corresponding to the desired size and shape of a mattress or the like. The adjacent rows of strings may be interconnected by a variety of methods. The result is a unitary assembly of pocketed coil springs serving as a complete spring core assembly. In an early form, the rows or strings of such a unitary assembly of pocketed coil springs were interconnected by mechanical fasteners such as staples, clips, or the like. More recently, various forms of adhesives applied to the side surface of a first row or string of pocketed coil springs are used to bond that row or string to an adjacent row or string and after this is repeated for multiple strings to thereby construct a unitary spring core assembly. One example of a spring core assembly constructed from a plurality of strings of pocketed coil springs glued together is disclosed in U.S. Patent No. 4,578,834. Each of the pocketed coil springs in the spring core disclosed in that patent includes a discrete hot melt adhesive deposit on the sidewall thereof . Specific shortcomings associated with that design include the limited bonding strength produced between the adjacent rows of pocketed coil springs because of the individualized discrete deposits of adhesive. Additionally, the requirement of cycling the adhesive applicator rapidly on and off while manufacturing such a spring core assembly can be problematic. Such demands on the adhesive applicator result in frequent maintenance problems and limited and unreliable production capacity. Spring core constructions manufactured with adjacent strings of pocketed coil springs adhesively bonded together are also disclosed in U.S. Patent Nos. 4,566,926 and 5,637, 1 78. The system disclosed in the '926 patent includes a hot melt adhesive applicator having a plurality of spray nozzles which apply hot melt adhesive to a selected portion of each pocketed coil spring. The applicator moves longitudinally along the length of a stationary string of pocketed coil springs to apply the hot melt adhesive. On the other hand, the system shown in the ' 1 78 patent requires the assembly of spring core constructions from strings of pocketed coil springs in which a first string of coil springs is moved on a conveyor and coated with adhesive sprayed from a fixed adhesive applicator. The manufacturing capacity of each of these systems is limited because of the requirement for a fixed adhesive applicator or a stationary string of pocketed coil springs onto which the adhesive is applied. In those systems, the production of spring core assemblies is the result of a discontinuous or batch like process. Furthermore, the adhesive is not efficiently and optimally applied to the strings of pocketed coil springs for a uniform and unitary spring core assembly. Further, known systems and methods for adhesively bonding strings together typically bond each pocketed coil spring to each adjacent pocketed coil spring in the adjacent rows. As such, the bonding systems and methods do not allow for customization of the spring unit by varying the bonding scheme to permit differential movement of selected pocketed coil springs relative to selected pocketed springs in adjacent strings or rows. These identified and other systems provide limited opportunities to manufacture spring core assemblies from pocketed coil springs. There is a need to provide a system and method which can be utilized on a production basis for more complete automation of the procedure for the expeditious and efficient manufacture of spring core assemblies from strings of pocketed coil springs adhesively bonded together while allowing for customization of the spring unit and portions thereof. Summary of the Invention It has therefore been a primary objective of this invention to provide an improved method and system for the manufacture of spring core assemblies from strings of pocketed coil springs. It has been a further objective of this invention to provide such a method and system which is expeditious, efficient, reliable and cost effective for application in a fully automatic production facility utilizing adhesive bonding of the adjacent strings. It has been a still further objective of this invention to provide such a method and system which consistently produces appropriately sized and standardized spring core assemblies from strings of pocketed coil springs on a consistent basis and further spring core assemblies which can be customized to include independently deflecting regions of springs. These and other objectives of the invention have been achieved by a system and method for manufacturing a spring core assembly for use in mattresses, seat cushions or the like. In a presently preferred embodiment, the method includes moving a first string of pocketed coil springs past a moving adhesive applicator in a direction generally perpendicular to the longitudinal axes of the coil springs and spraying adhesive from the applicator onto a side surface of the moving pocketed coil springs. Advantageously, the adhesive applicator is also moving so the manufacturing method includes a moving adhesive applicator applying adhesive to a moving string of pocketed coils springs to provide a pattern of adhesive on the central portion of each individually pocketed coil spring. The movement of the adhesive applicator allows for enhanced control of the location of the adhesive on the strings without restricting the travel of the strings and the resulting production speed. Preferably, the movement of the adhesive applicator substantially follows or is synchronized with each pocketed coil spring of the string. In one presently preferred embodiment of this invention, multiple nozzles for dispensing the adhesive from the adhesive applicator are used so that each pocketed coil spring or groups of springs may be followed with one or more nozzles over a limited range of movement. Furthermore, multiple nozzles offer the advantage of avoiding a single nozzle moving over a limited range with great speed or high frequency and thereby minimizing potential maintenance problems for the system while increasing the precision and accuracy of applying the adhesive. The individual nozzles may independently and selectively spray adhesive onto the string. In presently preferred embodiments of this invention, the adhesive applicator moves over a limited range in a rotational manner or a reciprocating fashion which may include pivotal movement, linear translational movement or other types of movement. In a still further presently preferred embodiment of the invention, the spray pattern on the string of pocketed coil springs is continuous and includes a greater amount of adhesive deposited on the central portion of each coil spring relative to the remainder of the adhesive pattern. This produces a greater bonding strength between the adjacent strings of pocketed coil springs because the central portion of each spring is typically the primary contact region between the strings of springs. A continuous spray pattern on the string of pocketed coil springs which results from the moving string and the moving adhesive applicator allows for the coils in each string to be pushed together and adhesively bonded to one another before connecting the string to an adjacent string. As a result, the individual strings can be sized to a standardized dimension which results in a more uniform spring core. The continuous adhesive deposited on the side surface of the string of pocketed coil springs helps in stabilizing and sizing the entire spring unit in comparison to systems where the adhesive is only deposited at discrete locations on the middle or tangential regions of the arcuate spring pocket. Furthermore, movement of the strings and the adhesive applicator provides for a more continuous production system and method in the manufacture of the spring core unit. In a still further presently preferred embodiment, the pattern of adhesive applied to the side of the moving string includes one or more lines which can be customized to change the deflection characteristics or feel of the resulting spring unit. In one form, sinusoidal lines of adhesive extend across groups of springs in each string so that the springs work as a sub-unit or block within the spring unit for individual deflection zone or regions. As a result of the present invention, systems and methods for manufacturing spring core assemblies from adhesively bonded strings of pocketed coil springs are provided which improve the production capability for such spring units while increasing the accuracy or precision of adhesive application and improving the quality of those spring units by providing in one form a more standardized and unitary spring core assembly and in other forms customized spring core assemblies. Brief Description of the Drawings The objectives and features of the invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which: Figs. 1 A - 1 C are sequential schematic representations of a first presently preferred embodiment of this invention for applying adhesive from a moving adhesive applicator onto a moving string of pocketed coil springs; Fig. 1 D is a schematic representation of a first string of pocketed coil springs being pushed into contact with a second string of pocketed coil springs having adhesive applied on a side surface thereof to form a spring core assembly; Figs. 2A - 2C are sequential schematic representations of a second presently preferred embodiment of this invention in which a single adhesive applicator reciprocates in a generally linear direction while applying adhesive to a moving string of pocketed coil springs; Fig. 3 is a schematic representation of a third presently preferred embodiment of this invention with multiple nozzles reciprocating in a generally linear direction while applying adhesive to the moving string of pocketed coil springs being sized by adhesively bonding adjacent coil springs together; Figs. 4A - 4C are sequential schematic representations of another presently preferred embodiment of this invention in which an adhesive applicator includes a plurality of rotating nozzles spraying adhesive onto a string of moving pocketed coil springs; Fig. 5 is a schematic representation of a fourth presently preferred embodiment of this invention with multiple nozzles moving and spraying adhesive onto a moving string of pocketed coil springs into a pattern on the strings; Figs. 6A - 6C are side elevational views of strings of pocketed coil springs with adhesive applied thereto in various patterns; Fig. 7 is a schematic representational view of a fifth presently preferred embodiment of this invention in which a moving adhesive applicator includes a plurality of spray heads for applying adhesive in a pattern onto a moving string of pocketed coil spring; and Figs. 8 and 9 are side elevational views of patterns of adhesive applied onto the side of a string of pocketed coil springs. Detailed Description of the Invention Referring to Fig. 1 D, a spring core unit 1 0 manufactured from strings of pocketed coil springs according to this invention is shown. The spring core 1 0 includes a plurality of strings 1 2 of pocketed coil springs 1 4. Each string 1 2 includes a plurality of pockets 1 4 encapsulating individual coil springs which are typically barrel-shaped with a plurality of normally spaced coils in which terminal end coils thereof have a smaller diameter than the intermediate coils. Alternatively, each pocket 1 4 may contain a compound nested coil spring or other spring designs as is well known in the art. Each pocketed coil spring 1 4 has a longitudinal axis 1 6 extending between the terminal end coils of each spring. Each pocket 1 4 for the coil springs has an upper and lower longitudinal end 1 8 spaced from a generally cylindrical or arcuate side surface 20 thereof. The strings 1 2 of pocketed coil springs 14 may be manufactured according to any known method or system such as the previously identified Spϋhl machines or the like. The spring core 1 0 is assembled by moving a first string 1 2a of pocketed coil springs having the side surface 20 thereof with a pattern of adhesive 22 thereon into contact with a similar second string 1 2b of pocketed coil springs. The adhesive 24 in the pattern 22 bonds the first and second strings 1 2a, 1 2b together and the process is repeated with the desired number of strings 1 2 of pocketed coil springs 1 4 until a spring core 1 0 of a desired size is assembled. The adhesive pattern 22 on the side surface 20 of the strings 1 2 of pocketed coil springs 1 4 in one form shown in Fig. 1 D is preferably located generally equidistance between the longitudinal ends 1 8 of the pockets 14 and is continuous across the side surface 20 of the pocketed springs. The adhesive pattern 22 of Fig. 1 D includes a region 26 of greater concentration of adhesive on each pocketed coil spring 1 4 which is located generally equidistance from the adjacent pocketed coil springs 1 4 of the string 1 2 or on the tangent of the pocketed coil spring 14. In other words, the region 26 of greater concentration of adhesive is generally located on the equator of the pocketed coil spring 1 4 and on a line perpendicular to the longitudinal axis of the string so that when the pocketed spring 1 4 is forced into contact with a similar shaped spring, the initial point of contact between them includes the region of greater concentration of adhesive 26 to thereby securely bond the strings 1 2 of pocketed coil springs 14 together. Preferably, only one side surface 20 of the string 1 2 of pocketed coil springs 1 4 is sprayed with the adhesive 24 so that as the strings 1 2 are sequentially assembled as shown in Fig. 1 D, each string 1 2 is adhesively bonded to the previous string 1 2. Referring to Figs. 1 A - 1 C, a first presently preferred embodiment of this invention is schematically and sequentially shown. The string 1 2 of pocketed coil springs 1 4 is moved on a conveyor or the like past a moving adhesive applicator 28 in the direction of arrow A generally parallel to the longitudinal axis of the string and perpendicular to the longitudinal axes 1 6 of the coil springs in the string 1 2. The movement of the adhesive applicator 28 may be rotational, reciprocating in a pivotal, translational or linear manner or any other type of movement. The adhesive applicator 28 includes a nozzle 30 for spraying adhesive 24 onto the side surface 20 of the moving string 1 2. Preferably, the adhesive 24, adhesive applicator 28 and nozzle 30 are selected from any one of a number of such components which are well known in the industry for this purpose. Preferably, according to the embodiment in Figs. 1 A - 1 C, the adhesive 24 is continuously sprayed from the nozzle 30 which, reciprocates and pivots about a pivot axis 32 as shown sequentially in the drawings. Preferably, the adhesive 24 being sprayed from the nozzle 30 is directed to one individual pocketed coil spring 1 4a of the string 1 2 at a time. Specifically, as shown in Fig. 1 A, as a specific pocketed coil spring 14a approaches the adhesive applicator 28, the nozzle 30 is directed to spray the side surface 20 of the pocketed coil spring 1 4a in a generally tangential orientation. As the specific pocketed coil spring 1 4a continues to travel in the direction of arrow A, the nozzle 30 pivots, as shown in Fig. 1 B, so that the adhesive spray 24 is continually directed towards that pocketed coil spring 1 4a. When the pocketed coil spring 1 4a is immediately in front of the adhesive applicator 28, the nozzle 30 is directed generally perpendicular to the direction of travel of the string 1 2 and produces a generally radially directed spray on the pocketed coil spring 1 4a. Continued movement of the string 1 2 as shown in Fig. 1 C is synchronized with continual pivoting of the nozzle 30 so that the spray 24 once again is in a generally tangential orientation relative to the circumference of the pocketed coil spring 1 4a. The nozzle 30 reciprocates back toward the position of Figs. 1 B and 1 A sequentially for continuous spraying of the specific pocketed coil spring 1 4a and then a subsequent adjacent coil spring 1 4b approaching the adhesive applicator 28. As a result of the coordinated movement of the adhesive applicator 28 and the string 1 2 of pocketed coil springs 1 4, the continuous pattern of adhesive 22 on the center part of the individual encased coil springs 1 4 is produced with the nozzle 30 substantially following and thereby spraying adhesive 24 onto each pocketed coil spring 1 4 as it passes the adhesive applicator 30. In one specific embodiment, the string 1 2 of pocketed coil springs 1 4 moves with a speed of approximately one meter per second which results in typically about 1 7 pocketed coil springs 1 4 per second moving past the adhesive applicator 30. As a result of the continuous spray 24 from the nozzle 30 and the movement of the adhesive applicator 30 relative to the moving string 1 2 of pocketed coil springs 1 4, primarily the radially directed spray as shown in Fig. 1 B, the pattern of adhesive 22 on the string 1 2 produces the region of greater concentration 26 of adhesive as shown in Fig. 1 D. Referring to Figs. 2A - 2C and Fig. 3, second and third alternative presently preferred embodiments of this invention are shown in which the adhesive applicator 28 moves by reciprocating in a linear direction or path that is generally parallel to the direction of travel of the string 1 2 of pocketed coil springs 1 4. In the embodiment of Figs. 2A - 2C, the nozzle 30 is focused on generally the center region of a specific pocketed coil spring 1 4a and follows the movement of that pocketed coil spring 1 4a at preferably the same velocity, for example, one meter per second, until it reaches the position of Fig. 2C at which time it reciprocates back through the position shown in Fig. 2B toward the position of Fig. 2A for direct spray upon a subsequent adjacent pocketed coil spring 14b in the string 1 2. As a result, the region of greater concentration of adhesive 26 is produced on each pocketed coil spring 1 4 in the string 1 2 as well as the continuous spray pattern on the string 1 2 due to the reciprocating movement of the applicator 28. As shown in Fig. 3, a plurality of nozzles 30, two of which are shown in Fig. 3, may be mounted upon the adhesive applicator 28 for direct and continuous spray on the string 1 2 of moving pocketed coil springs 1 4. Referring to Figs. 4A - 4C, a fourth presently preferred embodiment is shown in which the adhesive applicator 28 includes a plurality of nozzles 30, six of which are shown, which rotate about an axis 34. The adhesive applicator 28 in this embodiment includes multiple nozzles 30, only one of which is activated at any given time for spraying the adhesive 24 onto the moving string 1 2 of pocketed coil springs 1 4 so that the adhesive 24 from the active nozzle 30a is sprayed onto a single pocketed coil spring 1 4a as it moves past the adhesive applicator 28. Once the particular nozzle 30a reaches the approximate position relative to the particular pocketed coil spring 1 4a shown in Fig. 4C, the adhesive 24 ceases to be sprayed from that nozzle 30a and begins to be discharged from the subsequent adjacent nozzle 30b and directed onto the subsequent adjacent pocketed coil spring 1 4b and the process begins once again as shown in Fig. 4A. Advantageously, the system of Figs. 4A - 4C produces a continuous adhesive pattern 22 on the string 1 2 of pocketed coil springs 1 4 which includes a region of greater concentration of adhesive 26 along the central part of each pocketed coil spring 1 4 as shown in Fig. 1 D. As will be readily apparent to one of ordinary skill in the art, to produce the adhesive pattern 22 as described, the movement of the adhesive applicator 28, whether pivotal, rotation, translational or the like, is preferably coordinated with the movement of the string 1 2 of pocketed coil springs 1 4. A still further advantage of the present invention is shown in Fig. 3. Particularly, known strings 1 2 of pocketed coil springs 1 4 include lateral seams 36 joining the adjacent pocketed coil springs 14 together. Due to the nature of the pocketing material and the string of pocketed coil springs, the length of the string 1 2 of a particular number of pocketed coil springs 14 may not be consistent because of the stretching of the fabric or the capability of the string 1 2 to be expanded by increasing or decreasing the spacing between the adjacent pocketed coil springs 1 4. A particular advantage of the system and method according to this invention is that the adjacent pocketed coil springs 1 4 in the string 1 2 may be adhesively bonded together to thereby standardize or size the length of each string 1 2. Specifically, the pattern of adhesive 22 sprayed onto the string 1 2 is generally continuous, a portion 38 of which is sprayed onto the region of the pocketed coil springs 1 4 adjacent to one another (i.e., bordering the region of greater adhesive concentration and adjacent the seams 36) . Therefore, the adjacent pocketed coil springs 1 4 can be adhesively bonded together by this region of adhesive 38 by forcing the adjacent pocketed coil springs 1 4 together at a single location for each string 1 2 as shown in Fig. 3 or at multiple locations for each string 1 2. As a result, the length of the string 1 2 of pocketed coil springs 1 4 can be standardized or sized for a more uniform spring core 10 having standardized and sized strings 1 2 of pocketed coil springs 1 4. Referring to Fig. 5, a fifth presently preferred embodiment is shown in which the adhesive applicator 28 which includes a plurality of nozzles 30, two of which are shown, are mounted upon a first link 40 proximate a first end 40a of the link 40. An opposite end 40b of the link 40 is pivotally coupled to a rotating disk, wheel or other rotational member 42 which rotates in a first direction indicated by arrow B. A second link 44 is pivotally coupled at a first end 44a to the first link 40 and pivotally coupled at a second opposite end 44b to a second rotating disk, wheel or other rotational member 46 which rotates in a similar direction as that of the first disk 42. The adhesive 24 is supplied to the individual nozzles 30 through a supply line (not shown) as will be readily understood by those of ordinary skill in the art. As a result of the coordinated rotation of the disks 42, 46 and the movement of the links 40, 44 and nozzles 30 mounted thereon, the adhesive 24 sprayed from the moving nozzles 30 produces a desired pattern 22 on the moving string 1 2 of pocketed coil springs 1 4. In one presently preferred form, the pattern 22 includes a first line 22a of adhesive 24 in a sinusoidal or modified sinusoidal arrangement and a second line 22b of adhesive 24 which is exactly out of phase with the first line 22a but likewise in a sinusoidal or modified sinusoidal arrangement as shown in Figs. 5 and 6A - 6C. Each of the lines 22a, 22b are formed by one of the nozzles 30. Specifically referring to the adhesive pattern shown in Figs. 6A and 6B, the sinusoidal or modified sinusoidal lines 22a, 22b have a period P which extends over multiple pocketed coil springs 14 in the string 1 2. Specifically, the period P of each of the lines 22a, 22b of adhesive in the pattern of Fig. 6A extends over six pocketed coil springs 14; whereas, the period P of each line 22a, 22b of adhesive in the pattern 22 of Fig . 6B extends over four pocketed coil springs 1 4. It should be readily appreciated that the patterns 22 of adhesive 24 shown and described herein are exemplary only and may take numerous other forms within the scope of this invention. As shown in Fig. 6C, the adhesive pattern 22 may include lines 22a, 22b of adhesive which have a period P of only two springs 1 2. However, particularly with respect to adhesive patterns 22 of Figs. 6A and 6B and similar adhesive patterns, the pocketed spring coils 1 4 grouped together in a single period P of the lines 22a, 22b of adhesive work together as a block of two, three or more coils when the strings 1 2 are assembled into a spring core assembly 1 0. Specifically, because of the intersection of the lines 22a, 22b of adhesive occur approximately at a transverse or lateral seam 36 adjoining adjacent pocketed springs 14, the grouping of three pocketed coil springs 1 4 of Fig. 6A and of two pocketed coil springs 1 4 of Fig. 6B combine with similarly positioned pocketed coil springs 1 4 and adjacent strings 1 2 to form a block of springs 1 4 which offer differential spring deflection characteristics relative to the adjacent block or grouping of pocketed coil springs 14. Therefore, the resulting spring core assembly 1 0 may include multiple zones, groupings or blocks of springs which may provide individual spring deflection regions or zones in the spring assembly for a customized spring unit 10. Because of the position of the intersection of the lines 22a, 22b of adhesive in the pattern 22 occurs at the seam 36, the adhesive 24 does not limit the movement of the adjacent springs 1 4 and blocks thereof on either side of the point of intersection. Referring to Fig. 7, a sixth presently preferred embodiment is shown in which the adhesive applicator 28 includes a plurality of nozzles 30, eight of which are schematically shown in Fig. 7. The adhesive applicator 28 in this embodiment translates linearly in a direction generally parallel to the direction of travel of the string 1 2. Similar to the embodiments shown in Figs. 2A - 2C and 3, the adhesive applicator 28 translates within a limited range and reciprocates back and forth within that range while applying adhesive 24 in a pattern 22 to the moving string 1 2. Importantly, with respect to the embodiment shown in Fig. 7, the speed of the traveling adhesive applicator 28 is slower than that of the moving string 1 2 of springs 1 4. For example, the string 1 2 of pocketed coil springs 1 4 typically moves with a speed of approximately one meter per second which results in about 1 7 pocketed coils springs 14 per second moving past a fixed location. As such, the rate of travel of the moving adhesive applicator 28 of Fig. 7 would be less than one meter per second, for example about 0.5 - 0.75 meters per second. This relatively slower rate of travel of the adhesive applicator 28 achieves a greater precision in positioning the adhesive 24 onto the moving string 1 2 without slowing or retarding the travel of the string 1 2 and thereby detrimentally impacting the production, efficiency and capability of the overall system. The movement of the adhesive applicator 28 allows for increased time to apply the adhesive 24 in a pattern 22 onto the string 1 2, preferably in a more precise and accurate manner to achieve the desired pattern 22 while still maintaining a high speed of production. Each nozzle 30 shoots or dispenses the adhesive 24 with great accuracy onto a specified portion of the moving string 1 2. Preferably, the individual nozzles 30 are selectively and independently cycled on/off to spray a deposit 22c of adhesive onto the string 1 2 with great precision and accuracy. As such, the precisely positioned deposits 22c combine or merge to form the lines 22a, 22b and generally the pattern 22 of adhesive. Presently preferred adhesive patterns 22 which can be produced in the system of Fig. 7 are shown in Figs. 8 and 9 in which Fig. 8 includes a pair of sinusoidal adhesive lines 22a, 22b directly out of phase; whereas, the pattern of Fig . 9 includes a single line 22a of adhesive 24 in a sinusoidal pattern 22. In both Figs. 8 and 9, the period P of each sinusoidal line of adhesive is two pocketed coil springs. From the above disclosure of the general principles of the present invention and the preceding detailed description of preferred embodiments, those skilled in the art will readily comprehend the various modifications to which this invention is susceptible. Therefore, we desire to be limited only by the scope of the following claims and equivalents thereof. WE CLAIM: 1 . A method for manufacturing a spring core comprising the steps of:

Claims: WE CLAIM: 1 . A method for manufacturing a spring core comprising the steps of: providing a first string of pocketed springs, the springs having longitudinal axes which are substantially parallel to each other; moving the first string past an adhesive applicator and in a direction generally perpendicular to the longitudinal axes of the springs; applying an adhesive from the adhesive applicator onto a side surface of the moving pocketed springs; moving the adhesive applicator so that the adhesive being applied therefrom forms a pattern on the side surfaces of the pocketed springs; moving the first string relative to a similar second string of pocketed springs so that the side surface of the second string with the adhesive applied thereto contacts the first string and thereby adhesively bonds the first and second strings together; and repeating the steps until the spring core of a desired size is manufactured. 2. The method of claim 1 wherein the moving of the adhesive applicator further comprises reciprocating movement. 3. The method of claim 1 wherein the moving of the adhesive applicator is limited to a plane generally parallel to the direction of movement of the pocketed springs. 4. The method of claim 1 wherein the moving of the adhesive applicator further comprises pivotal movement. 5. The method of claim 1 wherein the moving of the adhesive applicator further comprises rotational movement. 6. The method of claim 1 wherein the moving of the adhesive applicator further comprises linear translational movement. 7. The method of claim 6 wherein a speed of travel of the adhesive applicator is generally equal to a speed of travel of the first string . 8. The method of claim 6 wherein a speed of travel of the adhesive applicator is less than a speed of travel of the first string. 9. The method of claim 1 wherein the applying of the adhesive further comprises spraying. 1 0. The method of claim 1 wherein the applying further comprises spraying the adhesive from a plurality of nozzles on the adhesive applicator. 1 1 . The method of claim 1 0 wherein the adhesive is sprayed from only one of the nozzles at a time. 1 2. The method of claim 1 0 wherein the adhesive is selectively sprayed from each of the plurality of nozzles. 1 3. The method of claim 1 wherein the pattern of adhesive includes a region of greater concentration of adhesive relative to a remainder of the pattern. 1 4. The method of claim 1 3 wherein the region of greater concentration of adhesive on each pocketed spring is located generally equidistance from adjacent pocketed springs of the first string and generally equidistance from longitudinal ends of the pocketed spring. 1 5. The method of claim 1 wherein the pattern of adhesive is generally sinusoidal. 1 6. The method of claim 1 5 wherein a period of the sinusoidal pattern of adhesive is generally equal to a width of an integral number of pocketed springs. 1 7. The method of claim 1 6 wherein the pattern includes multiple, out-of-phase sinusoidal lines of adhesive. 1 8. The method of claim 1 wherein the pattern of adhesive is generally continuous along the first string of pocketed springs. 1 9. The method of claim 9 wherein the spraying of the adhesive is generally continuous and is generally directed to only one of the pocketed springs at a time. 20. The method of claim 1 further comprising: bonding at least selected ones of the pocketed springs of the first string to adjacent pocketed springs of the first string to thereby regulate a length of each string of pocketed springs. 21 . A method for manufacturing a spring core comprising the steps of: providing a first string of pocketed springs, the springs having longitudinal axes which are substantially parallel to each other; moving the first string past an adhesive applicator and in a direction generally perpendicular to the longitudinal axes of the springs; generally continuously spraying an adhesive from the adhesive applicator onto a side surface of the moving pocketed springs, the spraying of the adhesive being generally on only one of the pocketed springs at a time; moving the adhesive applicator within a plane generally parallel to the direction of movement of the pocketed springs so that the adhesive being sprayed therefrom forms a pattern on the side surfaces of the pocketed springs, the pattern of adhesive being generally continuous along the first string of pocketed springs and including a region of greater concentration of adhesive relative to a remainder of the pattern, the region of greater concentration of adhesive being located generally equidistance from adjacent pocketed springs of the first string and generally equidistance from longitudinal ends of the pocketed spring; moving the first string relative to a similar second string of pocketed springs so that the sprayed side surface of the second string contacts the first string and thereby adhesively bonds the first and second strings together; and repeating the steps until the spring core of a desired size is manufactured. 22. The method of claim 21 wherein the moving of the adhesive applicator further comprises reciprocating movement. 23. The method of claim 21 wherein the moving of the adhesive applicator further comprises pivotal movement. 24. The method of claim 21 wherein the moving of the adhesive applicator further comprises rotational movement. 25. The method of claim 21 wherein the moving of the adhesive applicator further comprises linear translational movement. 26. The method of claim 21 wherein the spraying further comprises spraying the adhesive from a plurality of nozzles on the adhesive applicator. 27. The method of claim 26 wherein the adhesive is sprayed from only one of the nozzles at a time. 28. The method of claim 21 further comprising: bonding at least selected ones of the pocketed springs of the first string to adjacent pocketed springs of the first string to thereby regulate a length of each string of pocketed springs. 29. A spring core manufactured according to a method comprising the steps of: providing a first string of pocketed springs, the springs having longitudinal axes which are substantially parallel to each other; moving the first string past an adhesive applicator and in a direction generally perpendicular to the longitudinal axes of the springs; applying an adhesive from the adhesive applicator onto a side surface of the moving pocketed springs; moving the adhesive applicator so that the adhesive being applied therefrom forms a pattern on the side surfaces of the pocketed springs; moving the first string relative to a similar second string of pocketed springs so that the side surface of the second string with the adhesive applied thereto contacts the first string and thereby adhesively bonds the first and second strings together; and repeating the steps until the spring core of a desired size is manufactured. 30. The spring core of claim 29 wherein the moving of the adhesive applicator further comprises reciprocating movement. 31 . The spring core of claim 23 wherein the moving of the adhesive applicator further comprises pivotal movement. 32. The spring core of claim 29 wherein the moving of the adhesive applicator further comprises rotational movement. 33. The spring core of claim 29 wherein the moving of the adhesive applicator further comprises linear translational movement. 34. The spring core of claim 33 wherein a speed of travel of the adhesive applicator is generally equal to a speed of travel of the first string. 35. The spring core of claim 33 wherein a speed of travel of the adhesive applicator is less than a speed of travel of the first string. 36. The spring core of claim 29 wherein the applying of the adhesive further comprises spraying . 37. The spring core of claim 29 wherein the applying further comprises spraying the adhesive from a plurality of nozzles on the adhesive applicator. 38. The spring core of claim 37 wherein the adhesive is sprayed from only one of the nozzles at a time. 39. The spring core of claim 37 wherein the adhesive is selectively sprayed from each of the plurality of nozzles. 40. The spring core of claim 29 wherein the pattern of adhesive includes a region of greater concentration of adhesive relative to a remainder of the pattern. 41 . The spring core of claim 40 wherein the region of greater concentration of adhesive on each pocketed spring is located generally equidistance from adjacent pocketed springs of the first string and generally equidistance from longitudinal ends of the pocketed spring. 42. The spring core of claim 29 wherein the pattern of adhesive is generally sinusoidal. 43. The spring core of claim 42 wherein a period of the sinusoidal pattern of adhesive is generally equal to a width of integral number of pocketed springs. 44. The spring core of claim 43 wherein the pattern includes multiple, out-of-phase sinusoidal lines of adhesive. 45. The spring core of claim 29 wherein the pattern of adhesive is generally continuous along the first string of pocketed springs. 46. The spring core of claim 36 wherein the spraying of the adhesive is generally continuous and is generally directed to only one of the pocketed springs at a time. 47. The spring core of claim 29 further comprising: bonding at least selected ones of the pocketed springs of the first string to adjacent pocketed springs of the first string to thereby regulate a length of each string of pocketed springs. 48. A method for manufacturing a spring core comprising the steps of: providing a first string of pocketed springs, the springs having longitudinal axes which are substantially parallel to each other; moving the first string past an adhesive applicator and in a direction generally perpendicular to the longitudinal axes of the springs; applying an adhesive from the adhesive applicator onto a side surface of the moving pocketed springs; moving the adhesive applicator within a plane generally parallel to the direction of movement of the pocketed springs so that the adhesive being applied therefrom forms a pattern on the side surfaces of the pocketed springs, the pattern of adhesive comprising at least one generally sinusoidal line of adhesive generally along the first string of pocketed springs; moving the first string relative to a similar second string of pocketed springs so that the side surface of the second string with the adhesive applied thereto contacts the first string and thereby adhesively bonds the first and second strings together; and repeating the steps until the spring core of a desired size is manufactured. 49. The method of claim 48 wherein the applying of adhesive produces the sinusoidal line in which a period of the sinusoidal line is generally equal to a width of an integral number of pocketed springs. 50. The method of claim 49 wherein the pattern includes a pair of sinusoidal lines of adhesive which are out-of-phase with each other. 51 . The method of claim 48 wherein the adhesive is sprayed from a plurality of nozzles on the adhesive applicator. 52. The method of claim 51 wherein the adhesive is selectively and independently sprayed from each of the nozzles so that each nozzle sprays a deposit of adhesive onto the first string and the deposits combine to form the pattern of adhesive. 53. The method of claim 48 wherein the position of the adhesive applicator relative to a top of each of the pocketed springs in the first string is generally constant. 54. A spring core manufactured according to a method comprising the steps of: providing a first string of pocketed springs, the springs having longitudinal axes which are substantially parallel to each other; moving the first string past an adhesive applicator and in a direction generally perpendicular to the longitudinal axes of the springs; applying an adhesive from the adhesive applicator onto a side surface of the moving pocketed springs; moving the adhesive applicator within a plane generally parallel to the direction of movement of the pocketed springs so that the adhesive being applied therefrom forms a pattern on the side surfaces of the pocketed springs, the pattern of adhesive comprising at least one generally sinusoidal line of adhesive generally along the first string of pocketed springs; moving the first string relative to a similar second string of pocketed springs so that the side surface of the second string with the adhesive applied thereto contacts the first string and thereby adhesively bonds the first and second strings together; and repeating the steps until the spring core of a desired size is manufactured.

Inventors: MOSSBECK NIELS S, WELLS THOMAS J, MOSSBECK, NIELS, S., WELLS, THOMAS, J.
Applicants: L & P PROPERTY MANAGEMENT CO, L & P PROPERTY MANAGEMENT COMPANY
Application year: 1999
Main classification: B23K19
IPC codes: A47C27, B05B13, B05D1, B05D3, B05D7, B29C65, C09J5, F16F1