WO2004009265A1

WO2004009265A1 - Method and apparatus for manufacturing spring assemblies

Info

Publication number: WO2004009265A1
Application number: PCT/GB2002/003304
Authority: WO
Inventors: Ian Whitworth
Original assignee: Springform Technology Limited
Priority date: 2002-07-19
Filing date: 2002-07-19
Publication date: 2004-01-29
Also published as: AU2002319441A1

Abstract

A method and apparatus for manufacturing coil spring assemblies comprising a plurality of coil springs with a plurality of spring profiles is described. A programmable logic controller (PLC) controls the position of spring coiling elements (701, 702), which govern the profile of a coil spring (712) formed from wire (704). The PLC (709) selects a spring profile from a plurality of spring profiles and adjusts the position of the spring coiling elements (701, 702) accordingly. In a single operation, a plurality of coil springs (712) with a plurality of profiles may be manufactured in an order defined by the user. The coil springs (712) are encapsulated in a fabric pocket to form a string of springs comprising a plurality of pocketed coil springs (712) with a plurality of spring profiles.

Description

METHOD AND APPARATUS FOR MANUFACTURING SPRING

ASSEMBLIES

Field of the Invention The present invention relates to a method and apparatus for manufacturing coil springs and pocketed coil spring assemblies.

Background to the Invention

A bed typically comprises a frame, a base, which may or may not be sprung, and a mattress. The mattress typically contains a plurality of springs.

The springs are produced in strings by coiling wire in a prior art spring coiling and pocket strip forming machine. Wire is pulled through a set of feed rollers and onto a set of coil forming elements including a "finger", which governs the diameter of the coil springs, and a "spreader", which governs the pitch of the coil springs. By moving the finger and the spreader during production of a spring, the profile of the spring may be altered. In this way, a spring with a variable diameter and/or a variable pitch may be produced.

The springs are formed into a "string" of springs. A string of springs 101 is illustrated schematically in Figure 1 herein. A plurality of springs 102 are each positioned in a corresponding fabric pouch 103 in such a way as to be aligned side by side with each other such that the longitudinal axis of the string is in a direction transverse to a longitudinal axis along the length of each spring 104. A seal 105 is effected in the fabric pouch between each spring. In this way, a string of springs comprising a plurality of pocketed coil springs is manufactured. The fabric pouch may comprise any suitable fabric, including polypropylene. The seal may be effected by any suitable means, including stitching, welding, stapling or gluing. Where the fabric pouch comprises polypropylene, welding is the preferred method of sealing.

P0802Spec A prior art machine for manufacturing such coil spring assemblies conventionally has a coiling device comprising a complex mechanical system of gears, cams and linkages. Consequently, it can take several hours to reset the machine for production of springs from one spring profile to another. Economic batch quantities of springs are therefore high.

A previous prior art disclosure, WO 99/50175 discloses apparatus for the production of pocketed coil spring assemblies comprising a programmable control means linked to a spring coiling element. This apparatus reduces the turn around time in resetting the apparatus from producing springs of one spring profile type to another to seconds, rather than hours.

Fig. 2 herein illustrates schematically a cut away plan view through a mattress 201. Strings of springs are glued to each other within the mattress. Adjacent strings of springs 202 and 203 are illustrated, with glue 204 between them. By varying the quantity of glue 204 between adjacent strings of springs, the firmness of the mattress can be varied. It will appreciated that varying the amount of glue between adjacent strings of springs along the length of the mattress will create a mattress with varying degrees of firmness along its length. In this way, the firmness of a mattress can be "zoned" to be of different levels of support along its length. For example, a mattress may be zoned to increase comfort at the user's shoulders.

To produce a zoning which gives an increased shoulder comfort zone, a zone of differing firmness springs need to be created across a width of a mattress. It is also occasionally a requirement to have two or three rows of springs which are slightly firmer, running from an upper end to a lower end of a mattress along its length, to separate two persons lying on the mattress side by side from rolling together. Each of these two prior art examples of zoned mattresses exist separately, but there is no prior art mattress having zoning across a width of a mattress and zoning along a length of a mattress in the same mattress, because zoning depends upon having individual strings which contain springs all of the same firmness, and therefore the direction of zoning depends upon the direction in which the strings of springs are aligned which can only be a single direction for one mattress in the prior embodiments.

It is a feature of the prior art mattresses, that zoning along a width of a mattress and zoning along a length of a mattress, cannot occur at the same time in the same mattress, because the strings of springs can only run in one direction across the mattress or another direction along the length of the mattress.

In a non - zoned bed, normally the strings of springs are aligned length ways, in order to maximize the length of string in the mattress, and therefore improve productivity during manufacture.

Another way of zoning a firmness profile of a mattress so as to have different regions of firmness on different zones of the mattress is to vary the firmness of the springs within individual pockets. However, prior art string manufacturing machines cannot easily produce strings having different types of spring within a single string of springs, because of the problem of resetting the coiling device to make springs of a different type.

In prior art machines where the coiling device is set mechanically using cams and rollers, changing the coiling device to make a spring of a different type takes a matter of hours. In the prior art disclosure WO 99/50175, although resetting the coiling device from producing springs of one profile type to another takes a matter of seconds, there is no facility for effecting such a change in real time within a production run. Resetting the machine involves manual intervention and requires that the machine is stopped for resetting the machine to produce a new spring profile.

Summary of the Invention

The inventor has conceived a means for manufacturing coil spring assemblies having different coil spring types in adjacent pockets in a single operation, without the need to halt a production run of a string, whereby springs with different properties may be included in one string of springs. In this way, both softer and firmer coil springs may be included in a same string of springs, and therefore zoning of firmness along the width of a mattress may be achieved using strings containing different spring types produced in a single production run, without stoppage.

Changes to the type of spring within different pockets of a same string can be made during the production run of the string without significant delay to the speed of manufacture of the string, that is, without loss of productivity, since the spring type can be varied in real time, from spring to spring, by controlling a set of spring coiling elements according to a spring profile data which can be changed electronically from spring to spring within a series of springs formed in a same string of springs.

Specific implementations according to the present invention rely upon storing data describing a plurality of different spring profiles, including variations in length, pitch, and changes in radius of curvature along the length of the spring, for different spring types manufactured from a same reel of wire input into a spring coiling machine. A set of spring coiling elements in a coiling device are driven by servo motors, which are controlled according the spring profile data in real time as a string of springs is manufactured. Successive springs being produced by the coiling device can be of different types, having different firmnesses, and made from a same input feed of wire.

Changes between spring types can be made in real time, so that a preceding spring inserted into a preceding pocket can be manufactured to a different spring profile type to a present spring inserted into a present pocket at a spring insertion point on the machine. As the machine moves forward to a new spring, a successive spring can be of a further and different spring profile yet again. A web of material is drawn through a pocket spring forming machine, and springs of different types are inserted into pockets formed from the web of material. The web of material is drawn through the machine substantially continuously, in a stop/start motion, at a speed which allows enough stoppage time for a spring to be inserted into a pocket formed from the web, before moving the web along and inserting a further subsequent spring. Adjacent springs within the string maybe of different spring types, and alternating between different spring types does not significantly slow the maximum speed at which the web of material can be drawn through the machine. A change of spring type can be accommodated within a stop/start cycle of the web through the machine, that is, within the time necessary for a spring to be inserted into a pocket, before further movement of the web through the machine for insertion of a next spring into a next pocket of a strip formed by the web. Typically, the strip moves through the machine at a rate in the range of 0.5 to 3 pockets per second, corresponding to an average speed of web material though the machine of the order 7 to 45 centimeters per second, and changes of spring type can be accommodated within this speed range.

Changes to the spring type are effected by means of an electronic control system, which stores a plurality of different spring type data in a memory device, for controlling a set of coiling elements which produce springs. Changing of spring type is substantially instantaneous, relative to the speed at which the web of material is drawn through the pocket spring forming machine, and can be accommodated within a stop/start sequence of the web, which gives enough time for a spring to be inserted inside a pocket. Consequently, the speed of the web of material through the machine is not necessarily limited or slowed down by changes to spring type, which are implemented electronically, within a stop/start cycle of the web during its passage through the pocket spring forming machine.

According to a first aspect of the present invention, there is provided a method of manufacturing a plurality of coil springs in a single operation, said coil springs having a plurality of different profiles, comprising; selecting a spring profile from a plurality of spring profiles;

setting positions of a set of spring coiling elements according to said selected spring profile;

manufacturing at least one coil spring by passing wire through said spring coiling elements, wherein said spring coiling elements are controlled in accordance with said spring profile ;

selecting a further spring profile from said plurality of spring profiles;

setting further positions of said spring coiling elements according to said selected further spring profiles; and

manufacturing at least one further coil spring by passing wire through said spring coiling elements, wherein said spring coiling elements are controlled in accordance with said further spring profile.

According to a second aspect of the present invention, there is provided an apparatus for manufacturing a plurality of coil springs in a single operation, said coil springs having a plurality of different profiles, said apparatus comprising:

a set of spring coiling elements, the actions of which govern the profile of a said coil spring formed by said spring forming elements;

means for passing wire to said spring coiling elements;

programmable control means for controlling the positions of said spring coiling elements; and

means for removing manufactured said coil springs from said wire. Said programmable control means may be operable for controlling said spring coiling elements to produce successive springs of different types, within a time scale which allows substantially continuous operation of said spring coiling elements within a production run of said plurality of springs.

According to a third aspect of the present invention there is provided a pocketed coil spring assembly comprising:

a plurality of coil springs having a plurality of different spring profiles;

a web of sheet material forming a plurality of pockets;

each said coil spring being encapsulated in a said pocket of said sheet material, said plurality of pockets being linked thereby forming a string of said pockets.

According to a fourth aspect of the present invention, there is provided a pocket strip forming machine for manufacturing a string of pocketed coil springs, said machine comprising:

a coiler device capable of forming a plurality of coil springs from a length of wire:

an encapsulation stage for inserting a plurality of coil springs by said coiling device into a web of material; and

a transport mechanism for transporting said coil springs from said coiler device to said encapsulation stage;

characterized in that, said coiling device is capable without stoppage or reduction in production speed of producing a plurality of said springs according to a plurality of different spring types, each spring type having a different set of mechanical properties.

According to a fifth aspect of the present invention, there is provided a method of initialization of a spring forming and pocketing machine, said machine comprising: a coiler device comprising a first coiling element for controlling a length of wire for said spring:

a first drive motor for controlling for said first coiling element:

a second coiling element for controlling a radius of curvature of said spring;

a second drive motor for controlling said second coiling element;

a transport mechanism for transporting a spring from said coiling device; an encapsulation mechanism for encapsulating a plurality of said springs in a plurality of pockets formed in web material;

a controller for controlling said first, second and third coiling elements, said transport mechanism, and said encapsulation mechanism, said controller comprising a memory capable of storing a plurality of spring profile data, each said spring profile data describing a radius and pitch of a said spring;

said initialization method comprising:

inputting into said memory, a plurality of spring profile data, representing a plurality of different spring profiles. According to a sixth aspect of the present invention, there is provided a controller device for controlling first and second servo motors for driving a first controller element and a second coiling element respectively for forming a length of wire into a plurality of coils without reduction in speed of production, said controller device component comprising:

a data processor and:

a memory device:

said memory device storing a first data table, said first data table comprising data describing control instructions for said first and second and servo motors for driving said first controller element and second coiling element to produce a first coil spring type: and

a second data table, said second data table containing data describing instructions for driving said first and second drive motors to control said first controller element and second coiling element for producing a second coil spring type:

wherein said controller device drives said first and second drive motors for producing sequentially, from a same length of wire, a first coil spring of a said first type, followed by a second coil spring of a said second type.

According to a seventh aspect of the present invention, there is provided a coiler machine for coiling a length of wire into a plurality of coil springs without reduction in speed of production, said coiler machine comprising:

a first coiler element for controlling a length of said wire;

a first drive motor for controlling said first coiler element; a second controller element for controlling a radius of curvature of said wire;

a second drive motor for controlling said second coiler element; and

a third coiling element for controlling a pitch of said wire;

a third drive motor for controlling said third coiling element; and an electronic controller for controlling said first, second and third drive motors to produce a plurality of springs of different types.

According to an eighth aspect of the present invention, there is provided a controller device for controlling first and second motors for driving a first coiling element and a second coiling element respectively for forming a wire into a plurality of coils, said controller component comprising:

a data processor and:

a memory device:

a plurality of data tables, each containing data describing control parameters for controlling said first and second drive motors to operate said first controller element and second coiling element, each said data table comprising control data for forming a corresponding respective spring type;

wherein said controller drives said first and second drive motors for produce sequentially, from a same length of wire, a first coil spring of a said first type, followed by a second coil spring of a said second type.

The invention includes a pocket coil spring assembly comprising a plurality of coil springs having a plurality of different profiles, said pocket coil spring assembly being manufactured in a substantially continuous operation, by a method comprising:

selecting a spring profile from a plurality of spring profiles;

selecting a further spring profile from said plurality of spring profiles;

Other aspects of the invention are as recited in the claims herein.

Brief Description of the Drawings For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which:

Fig. 1 illustrates schematically a string comprising a plurality of springs encased in a plurality of fabric pockets. Fig. 2 illustrates schematically in plan view, a spring mattress, showing an arrangement of strings of springs;

Fig.3 illustrates schematically a mattress spring;

Fig. 4 illustrates schematically a spring forming and pocketing machine used to manufacture pocketed coil spring assemblies according to a specific implementation of the present invention;

Fig. 5 illustrates a view of a coiler device for forming springs;

Fig. 6 illustrates a further view of the coiler device;

Fig. 7 illustrates schematically internal components of the coiler device, and control components of a controller, for producing coil springs of differing dimensions;

Fig. 8 illustrates schematically components of a programmable logic controller (PLC) for controlling operation of the machine;

Fig. 9 illustrates schematically an interaction of a spring profile data table with a wire feed servo data within the controller;

Fig. 10 illustrates schematically process steps carried out by the PLC to control the machine to manufacture a plurality of coil springs;

Fig. 11 illustrates schematically steps required to manufacture a test spring;

Fig. 12 illustrates schematically part of a string manufacture process carried out by the machine for a single coil spring and encapsulating the single coil spring within a string; Fig. 13a illustrates schematically a first pattern of coil springs in a string manufactured according to a specific method described herein; and

Fig. 13b illustrates schematically a second pattern of coil springs in a string manufactured according to a specific method described herein.

Detailed Description of the Best Mode for Carrying Out the Invention

There will now be described by way of example the best mode contemplated by the inventor for carrying out the invention. In the following description numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present invention.

In this specification, the term 'string' refers to an elongate assembly of coil springs in which a plurality of coil springs are arranged side by side to each other in a row, joined by a continuous web of material which is divided into a series of pockets, each suitable for containing at least one spring, the pockets arranged sequentially along a length of the string. The term 'pocket strip' is used interchangeably with the term 'string' to mean the same thing.

The term 'pocket spring forming machine' is used to mean a machine suitable for forming a pocket strip or a string of springs. A pocket spring forming machine manufactures strings of pockets. The term 'pocket spring forming machine' is used interchangeably with the term 'spring forming and pocketing machine' to mean the same thing.

Referring to Fig. 3 herein, there is illustrated schematically a typical mattress spring 301. The spring can be characterized by a spring profile data comprising information about the dimensions of the coil spring, including coil spring length 302, coil spring diameter 303, coil spring pitch 304, variations of coil diameter along the length of said coil spring, and variations of the coil spring pitch along the length of the coil spring. A centre 305 of the spring and a central longitudinal axis 306 along the length of the spring are also shown.

Referring to Fig. 4 herein, there is illustrated schematically a spring forming and pocketing machine for producing a continuous assembly of pocketed coil springs (herein referred to as a string). The machine is shown schematically in plan view. The machine comprises a chassis 400, forming a platform to which individual physical components and stages of the machine are physically attached: a coiler device 401 having a spring forming mechanism including a plurality of coiling elements for inputting an elongate length of wire 402 stored on a coil 403, and producing a plurality of coil springs from the wire, the coil forming mechanism 401 comprising a set of feed rollers which pull the wire the feed rollers being driven by a feed roller motor 404; a 'finger' device which governs the diameter of the spring as it is formed, and a 'spreader' device, which controls the pitch of the coil spring formed, the finger device and the spreader device, being controlled by corresponding respective first and second servo motors 405, 406; a transport wheel 407 (known as a 'windmill'), having a plurality of radially extending arms, the transport wheel being driven by a third motor 408, the transport wheel operating to load a spring output from the coiling device 401 onto a radially extending arm, and transport that spring towards a web of material 409, supplied from a reel 410, the coil spring being carried on a radial arm and guided by upper and lower sets of guides into a channel 411 which compresses the coil spring, and leaves the coil spring to be enclosed by folds of the web 409 as it is urged by the transport wheel into the guide and along the guide towards the web material and through a first roller set 412: a compactor plate 413 for maintaining compression of a plurality of coil springs placed within the web 409 as the web moves along the machine: a sealing mechanism 414 for sealing individual coil springs into pockets formed by sealing folds of the web material 409 around each coil spring to form a string 415; a second roller set 416 driven by a fourth motor 417, whereby string 415 is drawn through the second roller set 416: an expander wheel 418, in the form of a spiral plate mounted on a drive shaft, rotating and in contact with the string 415, for expanding the springs within the pockets, so that the springs extend to fill the series of pockets within the spring, the expander wheel 418 being powered by a drive belt mechanism 419 and sixth motor 420; an exit guide 421 comprising a substantially 'U' shaped channel, for guiding the string out of and away from the machine: and a power supply and control unit 422 in the form of a cabinet containing power supplies to each of the servo motors, and a programmable logical controller, for controlling operation of each servo motor, power and control data being supplied from the control unit 422 for each of the servo motors via a wiring loom 423, shown schematically.

The transport wheel 407, channel 411 , compactor plate 413, and sealing mechanism 414 comprise an encapsulation section for encapsulating coil springs in pockets.

In use, the spring forming and pocketing machine operates to input the wire 402 into the coiler device 401, to form a plurality of coils, having different dimensions, and therefore different firmnesses, place the formed coils within the web of material under compactor plate 413, seal the coil springs into individual pockets, in sealing device 414, expand the coil springs within the individual pockets, using expander wheel 418, and output the string 415 from the machine. The resulting string comprises a plurality of pocketed coil springs, sealed within pockets of fabric or other sheet material.

Referring to Fig. 5 herein, there is illustrated the coiler device 401. The wire

402 enters the coiler device 401 via the wire feed 500 controlled by a feed roller servo motor 404.

Referring to Fig. 6 herein, there is illustrated a further view of the coiler device 401. The second servo motor 406 that governs the position of the spreader is shown. Referring to Fig. 7 herein, there is illustrated schematically internal components of the coiling device for forming coil springs, and control components from the controller, for controlling the coiling device for production of a sequence of different coil springs having different dimensions, in real time.

The coiling device 700 comprises a set of spring coiling elements including a finger component 701 controlling a radial position of the wire about a main central axis of a helical coil spring 712 being formed from the wire: a spreader component 702, which controls a pitch of turns of the helical coil spring being formed: a cutter 703, which cuts the spring from the main feed of wire 704, once the spring is formed; a pair of feed rollers 705 for drawing the wire into the coiling device; first servo motor 706 for controlling the finger 701 ; second servo motor 707 for controlling the spreader device 702; and a motor 708 for controlling the feed rollers 705.

The coiling device 700 is controlled by programmable control means 709, which also controls fourth motor 710, driving the transport wheel 713, and fifth servo motor 711 , for controlling the rate of speed of the web through the encapsulation section.

Control of the spring forming and pocketing machine will now be described.

The programmable control means 700 comprises a programmable logic controller (PLC). The PLC controls the positions of the spring coiling elements in the spring forming section. The positions of the spring coiling elements are governed by first and second servo motors 706, 707 respectively, the positions of which are governed by the PLC.

The feed rollers pass the wire to the spring coiling elements. The wire 704 is passed through the wire feed rollers 705 onto the finger 701 and the spreader

702. The finger and the spreader coil the wire to give a completed coil spring 708 with the desired spring profile. The completed coil spring is removed from the wire by cutter 703, which is synchronized by the PLC. Once the coil spring has been removed from the wire by the cutter, it is passed onto a radial arm of the "windmill" transport wheel 713. The windmill comprises a revolving wheel with radial arms onto which the completed coil springs are passed. The movement of the transport wheel is also synchronized by the PLC and rotated via the fourth motor 710, and moved incrementally after the production of each completed coil spring, to transfer the completed coil spring to encapsulation section 714, wherein the completed coil springs are encapsulated in fabric pockets. The encapsulation section 714 is also controlled by the PLC, to synchronize its movements with the coil spring productions. In the encapsulation section, a completed coil spring that has been transferred by the transport wheel is positioned between two folds of fabric of the web. After the insertion of each coil spring, the PLC instructs the encapsulation section to index the position of the fabric by means of a servo motor. This allows the fabric to move in readiness to receive the next coil spring. Seals are effected by welding the sheet material between each coil spring to effect a string of pocketed coil springs.

The PLC is connectable to computer device 715 such as a personal computer, lap top computer, Psion ® device or other data entry terminal , whereby data can be transferred between the electronic device and the PLC.

The electronic device comprises a personal computer, which can be used to transfer spring profile data from the personal computer to the PLC, or to monitor the production. Spring profile data is entered into the personal computer 715 using a spreadsheet package such as Microsoft Excel.

During manufacture of a coil spring, the spring coiling elements govern the profile of the coil spring. The finger governs the coil spring diameter and the spreader governs the coil spring pitch. By varying the positions and orientations of the finger and spreader during manufacture, a coil spring with variation in diameter and/or pitch along its length may be manufactured. Referring to Fig. 8 herein, there are illustrated schematically components of the controller 700. The PLC comprises a microprocessor 801 , a program 802, contained in a read only memory (ROM), a random access memory (RAM) 803, and a plurality of user programmable data registers 804.

The registers 804 include mode data 805, which are programmed by a user to instruct the PLC to selectively access spring profile information from a plurality of spring profiles during a single operation. A plurality of spring profiles 806 are stored as data arrays in the registers of the PLC. In addition, repeat data 807 are stored in the registers 804 of the PLC.

The mode data arrays 805 contain information about the location in the registers of specific spring profiles 806. In this way, the PLC may access selectively a particular selected spring profile from the plurality of spring profiles 806. During operation, the spring profile data 806 is temporarily stored in the RAM 803. The RAM 803 may store a plurality of spring profile data array 806 at the same time. In this way, the PLC accesses selectively more than one spring profile from a plurality of spring profiles during a single operation. A mode data array 805 is programmed by a user to instruct the PLC to access selectively spring profile data arrays from the plurality of spring profile data arrays 806 during a single operation, thereby manufacturing a plurality of coil springs having a plurality of different profiles as required by the user.

The spring profile data arrays 806 comprise information that can be interpreted by the PLC to send signals to the servo motors for adjusting the positions of the spring coiling elements accordingly. Each spring profile data array 806 comprises positional data for the servo mechanical motors that control the positions and orientations of the finger and the spreader. Variations in the information contained in the spring profile data arrays 806 instruct the servo motors to alter the positions of the spring coiling element during manufacture of a coil spring, thereby effecting a coil spring with variations in diameter and/or pitch along the length of said coil springs. Typically, mattress springs are symmetrical about their centres. In one embodiment to produce such a symmetrical spring, a spring profile data array 806 contains information from one end of the spring to the centre of the spring. A repeat data array 807 instructs the PLC to repeat the instructions from the spring profile data array to the servo mechanical motors in reverse order, thereby effecting a coil spring that is symmetrical about the centre of the coil springs.

Referring to Fig. 9 herein, there is illustrated schematically an interaction of a spring profile data table with the wire feed servo motor. The spring profile data table comprises many pairs of coordinates e.g. a thousand, each pair of coordinates comprising positional data for the finger servo motor and the spreader servo motor. The PLC monitors the movement of the wire feed servo motor 903 via a feedback loop. For each wire feed servo motor 903 increment 904 of 0.5 mm, the PLC reads a new set of coordinates from the spring profile data array 1306 which give new positions for the finger servo motor 901 and the spreader servo motor 902.

Referring to Fig. 10 herein, there are illustrated schematically steps carried out by the PLC, to manufacture a coil spring. At the start of a production run

1001 , the PLC reads mode data 1002. The mode data contains information about which spring profile is required 1003. Where a first spring profile (1) is required, the PLC accesses the data table for that first spring profile 1004. The information from the data array for the first spring profile data is sent to the servo motors 1005. The servo motors control the positions of the spring coiling elements, thereby controlling the manufacturing of the coil spring. The PLC accesses repeat data for spring profile 1 1006. If repeat data is required 1007, then information from the first spring profile data array 1 is sent to the servos a second time 1008, to effect a spring that is symmetrical about its centre. Once repeat data has been sent to the servo motors, or if repeat information is not required, then the manufactured coil spring is complete 1009. A cutter is used to remove the spring from the wire 1010. The spring is located on a radial arm of the transport wheel, which indexes 1011 to remove the completed spring from the spring forming section. The PLC is programmed to either manufacture a further spring 1012 or to finish the production run 1013. If a further spring is required, then the PLC goes back to the stage of reading the mode data 1002. The mode data instructs the PLC to select a second and further spring profile 1003. Where second spring profile 2 is required, second spring profile data array 2 is accessed 1014. This information is sent to the servo motors 1015 to manufacture second spring 2. The repeat data is accessed 1016 for second spring profile 2. Where repeat data is required 1017, the information from spring profile 2 is sent to the servo motors a second time 1018 to effect a second spring 2 that is symmetrical about its centre. The completed second spring 1009 is then removed from the wire 1010 and indexed away from the spring coiling area 1011.

In this way a plurality of coil springs with a plurality of coil spring profiles may be produced. The PLC may be programmed to produce coil springs each having a predetermined and selected desired coil spring profile, in any order and from a same reel of wire, where the coil springs of different types are produced serially, one after the other by the same set of coiling elements.

Referring to Fig. 11 herein, there are illustrated steps for setting the machine for manufacturing a test spring before going to a full production run. The power to the apparatus is turned on 1101 , and the servo motors are referenced to a zero point 1102. The positions of the finger and the spreader are governed by rotational servos, which are rotated to a proximity switch and then rotated to a set position away from the proximity switch, thereby setting a zero point. Manual adjustments are made to the apparatus 1103, including inserting the wire to the feed rollers when necessary and checking that the wire is running without torsion by a machine operator. The operator then accesses a setup interface 1104, which allows different parameters 1105 to be set; a spring profile data array is selected, and transferred from the data registers to the RAM; adjustments are made to the spring profile data array to give variations in the dimensions of the coil spring; the number of springs in the batch are set; the speed of the production run is set; the mode of operation is set, which is used to inform the PLC how many different spring profile data arrays are required, and the order in which springs are made is also set. A test spring is then made 1106. If a produced test spring does not have the required dimensions or properties 1107, then an operator goes back to the setup interface stage 1104. If this spring does have the required dimensions and properties then the operator may go to a full production run 1108.

Referring to Fig. 12 herein, there are illustrate schematically processes carried out by the machine under control of the controller for manufacturing and encapsulating a single coil. The manufacture of a string of springs may be split broadly into two categories; coil spring production 1201 and coil spring encapsulation 1202. During spring production 1201 , the position of the feed rollers 1203 prompts the PLC 401 to give new positional data to the finger and spreader motor 1204. A different table can be selected every time for controlling the finger and spreader in step 1205, so that successive springs can be manufactured to different types, according to different spring profile data. A completed spring is cut from the wire 1205, and moved away from the coil spring production area to the encapsulation area via the windmill 1206. In the spring encapsulation area 1202, the spring is removed from the windmill and located in a cassette 1208. The cassette is moved into the fabric pocket and a clamp fixes the coil spring into the fabric pocket in step 1208 whilst the cassette is retracted in step 1209, leaving the spring enclosed between two folds of fabric. The fabric sheet is moved away from the transport wheel in step 1210 by an incremental distance to allow room for the next coil spring. The fabric is then sealed between the coil springs be welding in step 1211.

Changing of the data to the finger and spreader servos occurs substantially instantaneously within the cycle shown in Fig. 12, and between individual increments of the windmill, where different types springs are being produced adjacent to each other. Where a run of springs are inserted in pockets adjacent to each other, where the spring type does not vary, it is not necessary to select a different data table to control the finger and spreader servo motors. Only when the different spring type is next in sequence, is it necessary to apply a different spring profile to the finger and spreader servo motors to produce a different spring type. In general, every time the web of fabric moves along and the windmill increments, the same, or a different spring profile can be used to control a finger and spreader servo motors to produce the next coil spring in sequence to be inserted into a next pocket of the string of springs.

In one example there is produced a string having alternate first and second spring types having first and second profiles respectively. In this example, springs with first and second spring profiles 1 and 2 are manufactured alternately by the coiling device. Springs with first profile 1 are formed and subsequently encapsulated. Once a first type spring with first spring profile 1 has been formed in the spring forming section, a second type spring with second spring profile 2 is formed. Once individual springs have been manufactured they are each encapsulated to form a pocketed coil spring assembly. The spring coiling area is therefore manufacturing alternate first and second type springs 1 and 2 and the encapsulation area is encapsulating alternate first and second spring types 1 and 2. This gives rise to a string of springs comprising a plurality of pocketed coil springs with alternate first and second spring profiles 1 and 2.

Referring to Fig. 13 herein, there are illustrated schematically two examples of patterns of coil springs with different profiles in a coil spring assembly.

In Fig. 13a there is illustrated a string of springs 1301 comprising coil springs with alternate profiles. The first type coil spring with a first profile 1303 is followed in the coil spring assembly by a second type coil spring with a second profile 1304, with welds between the coil springs 1302. This pattern is repeated along the length of the string of springs 1301. In Fig. 13b, the string of springs comprises a spring of first profile 1 followed by two springs with second profile 2, two springs with first profile 1 , two springs with second profile 2 and a further spring with first profile 1.

The pocketed coil spring assembly comprises a plurality of coil springs having a plurality of different coil spring profiles, with each coil spring encapsulated in a fabric pocket. The coil springs are aligned in a direction transverse to the longitudinal axis of the coil springs, and said fabric pockets are linked thereby forming a string of springs. The plurality of coil springs with the plurality of coil spring profiles are located in a defined order within the string of springs. The defined order is that which is stored in the controller data table, to which the string of springs was manufactured.

The plurality of coil spring profiles will give a plurality of coil springs with different elastic properties. The elastic properties of the coil springs affect the firmness of a mattress manufactured from the string of springs. By including a string of springs containing a plurality of coil springs with a plurality of spring profiles in a mattress, the firmness of the mattress may be zoned along its length or across its width or in any appropriate pattern.

Pocketed coil spring assemblies produced by the methods described herein include a pocketed coil spring assembly comprising a plurality of coil springs having a plurality of different spring profiles, the coil springs inserted into a web of sheet material forming a plurality of pockets said plurality of pockets being linked thereby forming a string of said pockets, said plurality of pockets being arranged in a line side by side, each said coil spring being encapsulated in a said pocket of said sheet material such that said plurality of coil springs having different spring profiles lie adjacent to each other in said line, wherein within said line, said plurality of different types of springs lie side by side.

A mattress may be formed from a plurality of such coil spring assemblies joined together, such that a single layer of springs extend across said mattress, wherein a plurality of springs of different types extend in a first direction along a length of said mattress in a single string, and a plurality of springs extend along a second direction across a width of said mattress in a single string.

Claims

Claims:

1. A method of manufacturing a plurality of coil springs in a substantially continuous operation, said plurality of coil springs having a plurality of different profiles, said method comprising;

selecting a spring profile from a plurality of spring profiles;

selecting a further spring profile from said plurality of spring profiles;

2. A method as claim in claim 1 , wherein said plurality of spring profiles are stored as electronic data for controlling said spring coiling elements

3. A method as claimed in claim 1 or 2, wherein said spring profile comprises information about the dimensions of said coil spring, said dimensions including;

a coil spring length; a diameter of said spring at a plurality of positions along a length of said coil spring;

a pitch of said spring at a plurality of positions along a length of said coil spring.

4. A method as claimed in any one of claims 2 to 4, wherein the positions of said spring coiling elements govern a diameter of said coil spring and a pitch of said coil spring.

5. A method as claimed in any one of the preceding claims, wherein said positions of said spring coiling elements are controlled by programmable control means.

6. A method as claimed in any one of the preceding claims, wherein positions of said spring coiling elements are governed by servo mechanical means, said servo mechanical means being controlled by a programmable means.

7. A method as claimed in any one of the preceding claims wherein said plurality of spring profiles are accessed selectively by a programmable control means.

8. A method as claimed in any one of the preceding claims wherein a programmable control means accesses selectively more than one spring profile from said plurality of spring profiles during a single operation.

9. A method as claimed in any one of the preceding claims wherein said plurality of spring profiles are stored as data arrays in a programmable control means.

10. A method as claimed in any one of the preceding claims wherein a mode data array instructs a programmable control means to select one or more spring profiles from a plurality of spring profiles prior to manufacture of said coil springs.

11. A method as claimed in any one of the preceding claims wherein a said spring profile comprises information about the dimensions of said coil spring from one end of said coil spring to the centre of said coil spring, and a repeat data array comprises information instructing a programmable control means to further access said spring profile, thereby effecting a spring profile that is symmetrical about the centre of said coil spring.

12. A pocket coil spring assembly comprising a plurality of coil springs having a plurality of different profiles, said pocket coil spring assembly being manufactured in a substantially continuous operation, by a method comprising:

selecting a spring profile from a plurality of spring profiles;

selecting a further spring profile from said plurality of spring profiles;

setting further positions of said spring coiling elements according to said selected further spring profiles; and manufacturing at least one further coil spring by passing wire through said spring coiling elements, wherein said spring coiling elements are controlled in accordance with said further spring profile.

13. Apparatus for manufacturing a plurality of coil springs in a single substantially continuous operation, said plurality of coil springs having a plurality of different profiles, said apparatus comprising;

means for passing wire to said spring coiling elements;

programmable control means for controlling the positions of said spring coiling elements;

means for removing manufactured said coil springs from said wire;

wherein said programmable control means is operable for controlling said spring coiling elements to produce successive springs of different types, within a time scale which allows substantially continuous operation of said spring coiling elements within a production run of said plurality of springs.

14. Apparatus as claimed in claim 13, wherein the spring coiling elements comprise:

a spring coiling element which governs the diameter of a coil spring; and

a spring coiling element which governs the pitch of a coil spring.

15. Apparatus as claimed in claim 13 or claim 14, wherein positions of said spring coiling elements are governed by servo motors, said servo motors being governed by said programmable control means.

16. Apparatus as claimed in any one of claims 13 to 15, wherein positions of a set of servo motors are governed by said programmable control means to alter the positions of said spring coiling elements during manufacture of said coil springs, thereby effecting coil springs with variations in diameter and/or pitch along the length of said coil springs.

17. Apparatus as claimed in any one of claims 13 to 16, wherein said programmable control means controls a means for passing wire to the spring coiling elements.

18. Apparatus as claimed in any one of claims 13 to 17, wherein said programmable control means accesses selectively said spring profile from a plurality of spring profiles, and adjusts the positions of said spring coiling elements according to said spring profile.

19. Apparatus as claimed in any one of claims 13 to 18, wherein said plurality of spring profiles are stored as a plurality of arrays of data.

20. Apparatus as claimed in any one of claims 13 to 19, wherein said programmable control means, accesses selectively more than one spring profile from said plurality of spring profiles during said single operation.

21. Apparatus as claimed in any one of claims 13 to 20, wherein said plurality of spring profiles are stored in said programmable control means.

22. Apparatus as claimed in any one of claims 13 to 21 , wherein at least one array of data comprising spring profile information comprises information about the dimensions of said coil spring from one end of said coil spring to the centre of said coil spring, and a repeat data array comprises further information instructing said programmable control means to further access said array of data comprising spring profile information, thereby effecting a spring profile that is symmetrical about the centre the said coil springs.

23. Apparatus as claimed in any one of claims 13 to 22, wherein a mode data array instructs a said programmable control means to select a spring profile from said plurality of spring profiles prior to manufacture of said coil springs.

24. Apparatus as claimed in any one of claims 13 to 23, wherein said mode data array is programmed by a user to instruct said programmable control means to access selectively spring profile information from said plurality of spring profiles during a single operation, thereby manufacturing a plurality of coil springs having a plurality of different profiles as required by the user during a substantially continuous operation.

25. Apparatus as claimed in any one of claims 13 to 24, wherein said programmable control means comprises a programmable logic controller.

26. Apparatus as claimed in any one of claims 13 to 25, wherein said programmable logic controller is connected to an electronic device whereby data can be transferred between said electronic device and said programmable logic controller.

27. Apparatus as claimed in any one of claims 13 to 26, wherein a plurality of arrays of data comprising a plurality of spring profiles comprise positional data for said servo motors.

28. Apparatus as claimed in any one of claims 13 to 27, wherein a plurality of coil springs are encapsulated in a fabric pocket such that said coil springs are aligned in a direction transverse to the longitudinal axis along the length of the springs.

29. A pocketed coil spring assembly comprising:

a plurality of coil springs having a plurality of different spring profiles;

a web of sheet material forming a plurality of pockets;

30. A pocketed coil spring assembly as claimed in claim 29, wherein said plurality of coil springs having a plurality of different spring profiles are located in said string in a predetermined order.

31. A pocketed coil spring assembly as claimed in claim 30, wherein said predetermined order is determined by a mode data stored in a memory, device, which determines an order in which said plurality of spring types are sequences along said string.

32. A mattress comprising at least one pocketed coil spring assembly as claimed in any one of claims 29 to 31.

33. A pocket spring forming machine for manufacturing a plurality of pocketed coil springs, said machine comprising:

a coiler device capable of forming a plurality of coil springs from a length of wire: an encapsulation stage for inserted a plurality of coil springs by said coiling device into a web of material; and

characterized in that, said coiling device is capable of producing a plurality of different spring types, each spring type having a different set of mechanical properties, and assembling a plurality of said different spring types in a substantially continuous operation.

34. The machine as claimed in claim 33, wherein said coiling device comprises:

set of feed rollers for inputting said length of wire;

a first drive motor for controlling said feed rollers;

a finger element for controlling a radius of curvature of said wire;

a second drive motor for controlling said finger element;

a spreader element for controlling a pitch of said wire;

a third drive motor for controlling said spreader element; and

a control means for controlling said first, second and third drive motors to control said first and second coiling element to produce said plurality of different spring types.

35. The machine as claimed in claim 33 or 34, operable for: inserting a plurality of coil springs of different types sequentially into a plurality of pockets formed in said web material

36. The machine as claimed in any one of claims 33 to 35, operable for controlling said first, second and third drive motors to form a plurality of different spring types by:

reading a plurality of sets of spring profile data from a memory; and

controlling first, second and third drive motors according to each said set of spring profile data to form a spring of a corresponding respective spring type according to each said spring profile data.

37. A method of initialization of a spring forming and pocketing machine, said machine comprising:

a coiler device comprising:

a first coiling element for controlling a length of wire of said spring;

a first drive motor for controlling for said first coiling element;

a second coiling element for controlling a radius of curvature of said spring;

a second drive motor for controlling said second coiling element;

a third coiling element for controlling a pitch of said wire; and

a third drive motor for controlling said third coiling element; a transport mechanism for transporting a spring from said coiling device:

an encapsulation mechanism for encapsulating a plurality of said springs in a policy of pockets formed in a web material:

a controller for controlling said first, second and third coiling elements, said transport mechanism, and said encapsulation mechanism, said controller comprising a memory capable of storing a plurality of spring profile data, each said spring profile data describing a radius and pitch of a said spring:

said initialization method comprising:

inputting into said memory, a plurality of spring profile data, representing a plurality of different spring profiles.

38. A controller device for controlling first and second servo motors for driving first and second coiling elements respectively for forming a length of wire into a plurality of coils, said controller component comprising:

a data processor and:

a memory device:

said memory device storing a first data table, said first data table comprising data describing control instructions for said first and second and servo motors for driving said first and second coiling elements to produce a first coil spring type: and

a second data table, said second data table containing data describing instructions for driving said first and second drive motors to control said first and second coiling elements for producing a second coil spring type: wherein said controller drives said first and second drive motors for producing sequentially, from a same length of wire, a first coil spring of a said first type, followed by a second coil spring of a said second type.

39. The controller device as claimed in claim 38,

wherein by sequentially reading said first data table followed by said second data table, said controller device drives a coiler device to operates to form a spring of said first type, followed by a spring of said second type, from a continuous feed of said wire, without pausing said wire feed.

40. The controller device as claimed in claim 38 or 39, operable for driving a wire cutter device, said wire cutter device operable for cutting a wire between production of a spring of said first type and a spring of said second type.

41. The controller device as claimed in claim 40, further operable for:

controlling a set a draw rollers, for drawing said wire to feed said wire to said first and second coiling elements.

42. The controller device as claimed in any one of claims 38 to 41 , wherein said data table comprises:

data for controlling said coiling elements to control a length of wire comprising a said spring type.

43. A coiler machine for coiling a length of wire into a plurality of coil springs, said coiler machine comprising:

a first coiler element for controlling a length of said wire; a first drive motor for controlling said first coiler element;

a second coiler element for controlling a radius of curvature of said wire;

a second drive motor for controlling said second coiler element;

a third coiling element for controlling a pitch of said wire;

a third drive motor for controlling said third coiling element; and

an electronic controller for controlling said first, second and third drive motors to produce a plurality of springs of different types.

44. The coiling machine as claimed in claim in 43, wherein said controller device is capable of controlling said first, second and third drive motors to switch from producing a first coil spring type to producing a second coil spring type, within a time scale which is faster than a time taken to;

insert a first coil spring into a first pocket of a strip; and

move the strip along for insertion of a second spring into a second pocket.

45. A controller device for controlling first and second motors for driving first and second coiling elements respectively for forming a wire into a plurality of springs, said controller component comprising:

a data processor and:

a memory device: a plurality of data tables, each containing data describing control parameters for controlling said first and second drive motors to operate said first and second coiling elements, each said data table comprising control data for forming a corresponding respective spring type;

46. A pocketed coil spring assembly comprising:

a plurality of coil springs having a plurality of different spring profiles;

a web of sheet material forming a plurality of pockets said plurality of pockets being linked thereby forming a string of said pockets;

said plurality of pockets being arranged in a line side by side, each said coil spring being encapsulated in a said pocket of said sheet material such that said plurality of coil springs having different spring profiles lie adjacent to each other in said line;

wherein within said line, said plurality of different types of springs lie side by side.

47. A mattress as claimed in claim 46, comprising a plurality of said pocketed coil spring assemblies joined together, such that a single layer of springs extend across said mattress, wherein:

a plurality of springs of different types extend in a first direction along a length of said mattress in a single string; and a plurality of springs extend along a second direction across a width ss in a single string.