Technical Field

[0001] The present disclosure relates to a lock stitch, a method of forming a lock stitch, and a lock stitching system to form a lock stitch.

Background

[0002] Manual sewing may involve a needle, carrying a thread, penetrating a fabric backing material surface from above, passing through the material, tensioning the thread and then passing it back through the material from the underside. Once the thread was tensioned a stitch was created on both the top side and underside of the material.

[0003] Advancements include sewing machines to mechanically sew thread to a backing material. An example of a sewing machine includes the disclosure in US patent 4,750 by Elias Howe, Jr.

[0004] Howe's invention introduced another thread on the underside of material, which was inserted through the loop created by the top needle withdrawing from it. This loop was formed because the smooth steel needle was larger than the hole it penetrated in the resilient fabric, causing the material to grip the needle with friction around its circumference, together with thread it was carrying. On withdrawing the smooth needle carrying the thread, because the thread had a higher coefficient of friction it was held in place by the material, causing a loop of the top thread yarn to be formed on the underside of the material. This phenomenon is the underlying principle of loop formation in sewing.

[0005] The underside thread, introduced by Howe, was then passed through the loop, the upper thread tensioned to close the loop, like a noose, capturing the underside thread by jamming it against the material on one side and the tightening top side thread. Once the compound joint between two yams and the material was solid, the top yam tensioning stopped the needle was moved to the next point at which it would penetrate the material and repeating the yarn locking process created a stitch, called a lock stitch. This process of forming lock stitches as repeated to form a line of lock stitches, thereby creating a stitch pattern on the top side of the material. In during this process the underside thread was passed back and forward through each new loop being formed to lock it in place.

[0006] The under thread was held on a spindle in a smooth bobbin casing which was small enough to pass backwards and forwards through each new loop to lock it in place: lock stitching turned sewing from a one sided to a two sided process. A limitation of the process was having to change the bobbin when the finite roll of underside thread was exhausted. Lock stitching, mechanised in sewing machines, became and remains the dominant method of sewing to this very day.

[0007] Bobbin size is a paradoxical problem: increasing the size to hold more under thread reduced the number of bobbin changes at the cost of having to create larger top thread loops to enable them to pass through. Increasing loop size required a longer stroke of the needle, which in turn created a larger and longer needle movement and yam tensioning system with a consequent increase in sewing machine size and cost. With a bobbin holding a finite length of under thread it is not possible to have uninterrupted sewing operation.

[0008] The stroke length of the needle is primarily determined by the diameter of the bobbin casing because the size of the loop created by the needle penetrating the backing material must enable the bobbin passing through it. The longer the stroke the greater the compression forces on the needle and the lower the dynamic performance. Importantly, the greater the length of top thread to be tensioned in locking the under thread the higher the failure rate of the top thread.

[0009] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0010] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. Summary

[0011] There is disclosed a method of forming a lock stitch, comprising:

- passing a first portion of a first thread through an aperture in a backing material from a first side of the backing material to an opposite second side of the backing material;

- forming a first loop, proximal to the second side, with the first portion of the first thread;

- passing at least part of a second loop of a second thread through the first loop;

- tensioning the first loop by withdrawing at least part of the first thread through the aperture from the second side towards the first side, wherein the lock stitch is formed by the first loop holding the second loop to the second side of the backing material.

[0012] In some examples, the method comprises forming a subsequent lock stitch, the method further comprising:

- passing a subsequent first portion of the first thread through a subsequent aperture in the backing material from the first side to the second side;

- forming a subsequent first loop, proximal to the second side, with the subsequent first portion of the first thread;

- passing at least part of a subsequent second loop of the second thread through the subsequent first loop; and

- tensioning the subsequent first loop by withdrawing at least part of the first thread through the subsequent aperture from the second side towards the first side, wherein the subsequent lock stitch is formed by the subsequent first loop holding the subsequent second loop to the second side of the backing material.

[0013] In some examples, the method further comprises selectively advancing the backing material to enable a specified displacement of the aperture and the subsequent aperture. [0014] In some examples of the method, passing the first portion of the first thread through the aperture in the backing material comprises piercing, with a first needle, the aperture in the backing material, wherein the first needle carries the first portion of the first thread from the first side to the second side of the backing material.

[0015] In further examples of the method, forming the first loop comprises withdrawing the first needle from the aperture, wherein at least part of the first portion of the first thread is retained proximal to the second side to form the first loop.

[0016] In some examples of the method, passing the second loop of the second thread through the first loop comprises: inserting a second reciprocating needle through the first loop from a feeding side of the first loop to a locking side of the first loop, wherein the second reciprocating needle carries a second portion of the second thread through the first loop to the locking side; and withdrawing the second reciprocating needle from the first loop, wherein at least part of the second portion of the second thread is retained at the locking side of the first loop to form the second loop.

[0017] In further examples of the method, passing at least part of the second loop of the second thread through the first loop further comprises: locating a support at the feeding side of the first loop; and passing the second reciprocating needle carrying the second portion of the second thread across or through the support, wherein the support grips at least part of the second thread to aid retaining the second loop at the locking side of the first loop.

[0018] In further examples of the method, the support comprises a resilient material, wherein the method further comprises gripping at least part of the second thread with the support.

[0019] In some examples, the method further comprises bonding the first loop to the second loop with an adhesive.

[0020] In some examples, the method further comprises bonding the first loop and the second loop to the second side of the backing material. [0021] There is also disclosed a method of manufacturing composites comprising a backing material and a pile formed of threads, wherein the threads of the pile are stitched to the backing material with the method described above.

[0022] There is disclosed a lock stitching system to form a lock stitch, the system comprising: a first reciprocating needle, a second reciprocating needle, and a first thread tensioner. The first reciprocating needle forms a first loop of a first thread at a second side of a backing material, wherein the first reciprocating needle is configured to: pierce an aperture in the backing material from a first side of the backing material to an opposite second side of the backing material, wherein the first reciprocating needle carries at least a first portion of the first thread and to pass the first portion from the first side to the second side; and withdraw from the aperture in the backing material, wherein at least part of the first portion of the first thread is retained proximal to the second side to form the first loop. The second reciprocating needle passes at least part of a second loop of a second thread through the first loop, wherein the second reciprocating needle is configured to: insert through the first loop from a feeding side of the first loop to a locking side of the first loop, wherein the second reciprocating needle carries a second portion of the second thread through the first loop to the locking side; and withdraw from the first loop, wherein at least part of the second portion of the second thread is retained at the locking side of the first loop to form the second loop. The first thread tensioner is configured to: tension the first loop by withdrawing at least part of the first thread through the aperture from the second side towards the first side, wherein the lock stitch is formed by the first loop holding the second loop to the second side of the backing material.

[0023] In some examples, the lock stitching system further comprises: a support, wherein the support is configured to locate at the feeding side of the first loop, and wherein the support grips at least part of the second thread to aid the second portion of the second thread to be retained at the locking side of the first loop.

[0024] In further examples, the support comprises a resilient material, wherein the resilient material is configured to grip at least part of the second thread.

[0025] In further examples, the support includes a support aperture, to enable the second reciprocating needle and second thread to pass through the support. [0026] In further examples, the support includes a clamping mechanism.

[0027] In some examples, the lock stitching system is configured to form a subsequent stitch. The first reciprocating needle forms a subsequent first loop of the first thread at the second side of the backing material, the first reciprocating needle further configured to: pierce a subsequent aperture in the backing material from the first side of the backing material to the opposite second side of the backing material, wherein the first reciprocating needle carries at least a subsequent first portion of the first thread and to pass the subsequent first portion from the first side to the second side; and withdraw from the subsequent aperture in the backing material, wherein at least part of the subsequent first portion of the first thread is retained proximal to the second side to form the subsequent first loop. The second reciprocating needle passes at least part of a subsequent second loop of the second thread through the subsequent first loop, wherein the second reciprocating needle is configured to: insert through the subsequent first loop from the feeding side of the subsequent first loop to the locking side of the subsequent first loop, wherein the second reciprocating needle carries a subsequent second portion of the second thread through the subsequent first loop to the locking side; and withdraw from the subsequent first loop, wherein at least part of the subsequent second portion of the second thread is retained at the locking side of the subsequent first loop to form the subsequent second loop. The first thread tensioner is further configured to tension the subsequent first loop by withdrawing at least part of the first thread through the subsequent aperture from the second side towards the first side, wherein the subsequent lock stitch is formed by the subsequent first loop holding the subsequent second loop to the second side of the backing material.

[0028] In some examples the lock stitching system further comprises an advancing mechanism to selectively advance the backing material relative to the first reciprocating needle and the second reciprocating needle to enable a specified displacement of the aperture and the subsequent aperture.

[0029] In further examples, the lock stitching system further comprises: a frame to support the backing material: wherein a first needle assembly of the first reciprocating needle and a second needle assembly of the second reciprocating needle are configured at respective positions on a first plane, and wherein the advancing mechanism moves the frame to advance the backing material across the first plane. [0030] In some alternative examples, the lock stitching system, further comprises: a frame to support the backing material, wherein at least a portion of the backing material is configured on a second plane; wherein a first needle assembly of the first reciprocating needle and the second needle assembly of the second reciprocating needle are selectively movable relative to the second plane by the advancing mechanism to enable the specified displacement of the aperture and the subsequent aperture.

[0031] In some alternative examples of the lock stitching system , a first needle assembly of the first reciprocating needle and the second needle assembly of the second reciprocating needle are configured at respective positions on a first plane, and wherein the advancing mechanism conveys the backing material across the first plane.

[0032] In some examples of the lock stitching system, the respective positions of the first needle assembly and the second needle assembly are selectively movable on the first plane.

[0033] In some examples of the lock stitch assembly, the advancing assembly conveys a portion of a roll of the backing material across the first plane.

[0034] In some examples, the lock stitching system further comprises: an adhesive applicator to apply an adhesive to bond the first loop to the second loop.

[0035] In some examples of the lock stitching system, the adhesive further bonds the first loop and the second loop to the second side of the backing material.

[0036] In some examples of the lock stitching system, the first reciprocating needle reciprocates on a first axis and the second reciprocating needle reciprocate on a second axis, wherein the first axis and the second axis are substantially perpendicular.

[0037] There is disclosed a lock stitch comprising: a backing material with a first side and an opposite second side, and an aperture; a first thread, wherein a first portion of the first thread passes through the aperture from the first side to the second side of the backing material, wherein the first portion further forms a first loop of the first thread proximal to the second side); and a second thread with a second loop passing, at least in part, through the first loop, wherein the lock stitch is formed by tension in the first loop of the first thread holding the second loop to the second side of the backing material. [0038] In some examples, the lock stitch further comprises a subsequent lock stitch, wherein the backing material further comprises a subsequent aperture displaced from the aperture, and wherein the subsequent lock stitch comprises: a subsequent first portion of the first thread passing through a subsequent aperture, wherein the subsequent first portion further forms a subsequent first loop of the first thread proximal to the second side; and a subsequent second loop passing, at least in part, through the subsequent first loop, wherein the subsequent lock stitch is formed by tension in the subsequent first loop of the first thread holding the subsequent second loop to the second side of the backing material.

[0039] In some examples, the lock stitch further comprises adhesive to bond the first loop to the second loop.

[0040] There is also disclosed a method of forming a lock stitch, comprising: passing a first portion of a first thread through an aperture in a backing material from a first side of the backing material to an opposite second side of the backing material;

- forming a first loop, proximal to the second side, with the first portion of the first thread;

- passing a second portion of a second thread through the first loop;

- tensioning the first loop by withdrawing at least part of the first thread through the aperture from the second side towards the first side; and

- severing the second portion of the second thread from a remainder portion of the second thread, wherein the lock stitch is formed by the first loop holding the second portion to the second side of the backing material.

[0041] In some examples of the method, passing the second portion of the second thread through the first loop comprises: feeding the second portion of the second thread through a lumen of a feeder and through the first loop, wherein the second portion is supported in the first loop, at least in part, by the feeder. [0042] There is disclosed a stitching system to form a lock stitch, the system comprising: a first reciprocating needle, a feeder, a first thread tensioner, and a cutter. The first reciprocating needle forms a first loop of a first thread at a second side of a backing material, wherein the first reciprocating needle is configured to: pierce an aperture in the backing material from a first side of the backing material to an opposite second side of the backing material, wherein the first reciprocating needle carries at least a first portion of the first thread and to pass the first portion from the first side to the second side; and withdraw from the aperture in the backing material, wherein at least part of the first portion of the first thread is retained proximal to the second side to form the first loop. The feeder with a lumen feeds a second thread through the first loop, wherein the feeder is configured to: feed a second portion of the second thread through the lumen and through the first loop, wherein the second portion is supported in the first loop, at least in part, by the feeder. The first thread tensioner is configured to: tension the first loop by withdrawing at least part of the first thread through the aperture from the second side towards the first side. The cutter is configured to sever the second portion of the second thread from a remainder portion of the second thread at the feeder. The lock stitch is formed by the first loop holding the second portion to the second side of the backing material.

Brief Description of Drawings

[0043] Figs. 1 to 5 illustrate side views of a sequence of forming a lock stitch;

[0044] Figs. 6 to 11 illustrate alternative side views of the sequence of forming a lock stich in Figs. 1 to 5, where the alternative side view are perpendicular to the views in Figs. 1 to 5;

[0045] Fig. 12 is a flow diagram of a method of forming a lock stitch;

[0046] Fig. 13 illustrates a thread tensioner feeding a first thread for the lock stitch;

[0047] Fig. 14 illustrates a thread tensioner withdrawing the first thread;

[0048] Fig. 15 illustrates an adhesive applicator to apply an adhesive to the lock stitch;

[0049] Fig. 16 illustrates a top view of a series of lock stitches; [0050] Fig. 17 illustrates a bottom view of the series of lock stitches of Fig. 16;

[0051] Fig. 18 illustrates a partial top view of a lock stitching system with a movable frame in a first position;

[0052] Fig. 19 illustrates a side view of the lock stitching system of Fig. 18 with the movable frame in the first position;

[0053] Fig. 20 illustrates a partial top view of the lock stitching system of Fig. 18 where the movable frame is moved to a second position;

[0054] Fig. 21 illustrates a side view of the lock stitching system of Fig. 20 with the movable frame in the second position;

[0055] Fig. 22 illustrates a side view of a lock stitch with a horizontal second loop;

[0056] Fig. 23 illustrates an alternative side view of the lock stitch in Fig. 22;

[0057] Fig. 24 illustrates a bottom view of the lock stitch in Fig. 22;

[0058] Fig. 25 illustrates a side view of a lock stitch with a vertical second loop;

[0059] Fig. 26 illustrates an alternative side view of the lock stitch in Fig. 25; and

[0060] Fig. 27 illustrates a bottom view of the lock stitch in Fig. 25.

[0061] Fig. 28 illustrates an alternative system for forming an alternative lock stitch;

[0062] Fig. 29 illustrates the alternative system of Fig. 28 with a cutter severing a second portion of a second thread;

[0063] Fig. 30 illustrates an alternative lock stitch formed with the system of Fig. 28;

[0064] Fig. 31 illustrates another view of the alternative lock stitch in Fig. 30;

[0065] Fig. 32 illustrates a bottom view of the alternative lock stitch in Fig. 30; and [0066] Fig. 33 is a flow diagram of a method of forming the alternative lock stitch of Fig.

28.

Description of Embodiments

[0067] Overview of the method 100 of forming a lock stitch 1

[0068] Fig. 2 illustrates steps in a method 100 of forming a lock stitch 1. Figs. 1 to 11 illustrate portions of a system 50 in a sequence to perform the method 100. The method 100 is directed to forming a lock stitch 1 with two threads, wherein a first loop 11 of a first thread 3 holds a second loop 12 of a second thread 13 against a backing material 5, as illustrated in Figs. 11, 16, and 17.

[0069] The method 100 includes passing 111 a first portion 2 of a first thread 3 through an aperture 4 in a backing material 5 from a first side 7 of the backing material 5 to an opposite second side 9 of the backing material 5. This can be done by piercing 105 the backing material 5 with a first reciprocating needle 8 carrying the first thread 3 as illustrated in Figs. 1 and 2 (with an alternative view in Figs. 6 and 7).

[0070] The method 100 further includes forming 121 a first loop 11, proximal to the second side 9, with the first portion 2 of the first thread 3. As illustrated in Fig. 3 (and Fig. 8), the first loop 11 can be formed by withdrawing the first needle 8 back through the aperture 4.

[0071] The method 100 also includes passing 131 at least part of a second loop 12 of a second thread 13 through the first loop 11. This can be achieved by inserting 135 a second reciprocating needle 14 carrying the second thread 13 through the first loop 11 (as illustrated in Fig. 9), and subsequently withdrawing 137 the second reciprocating needle 14 from the first loop 11 (as illustrated in Fig. 10). At least part of the second thread 13 is retained in the first loop 11, as illustrated in Fig. 4.

[0072] The method also includes tensioning 151 the first loop 11 by withdrawing at least part of the first thread 3 through the aperture 4 from the second side 9 towards the first side 7, wherein the lock stitch 1 is formed by the first loop 11 holding the second loop 12 to the second side 9 of the backing material 5. In some examples, tensioning 151 of the first loop 11 is achieved with a first thread tensioner 25 to tension and withdraw at least part of the first thread 3 as illustrated in Fig. 14.

[0073] The result is a lock stitch 1 and an example of which is illustrated in Figs. 5 and 11. The lock stich 1 can be repeated with subsequent first loops and subsequent second loops to form further stitches, where the first and/or second threads 3, 13 are joined to provide multiple stitches as illustrated in Figs. 16 and 17.

[0074] Detailed example of a system 50 to form a lock stitch 1

[0075] A non-limiting example of a system 50 for forming a lock stitch 1 will now be described in detail. The lock stitching system 50 includes a first reciprocating needle 8 which is configured to form the first loop 11 of the first thread 3. The first reciprocating needle 8, in the example illustrated in Figs. 1 to 11, is configured to reciprocate on a first axis 43 that is substantially perpendicular to the first and second side 7, 9 of the backing material 5. The first reciprocating needle 8, and associated first needle assembly 35, is configured to be facing the first side 7, which in Figs. 1 to 11 is above the backing material 5. This reciprocating motion includes the first needle 8 piercing 105 an aperture 4 in the backing material 5 from a first side 7 to the opposite second side 9. The first reciprocating needle 8 includes a lumen 51 for the first thread 3, to enable the first reciprocating needle 8 to carry at least a first portion 2 of the first thread 3 and to pass least the first portion 2 of the first thread 3 from the first side 7 to the second side 9. The reciprocating motion also withdraws 123 the first reciprocating needle 8 from the aperture 4 in the backing material 5, and wherein at least part of the first portion 2 of the first thread 3 is retained proximal to the second side 9 to form the first loop 11. This may include resilience in the backing material 5 to grip and provide friction against the first thread 3. In some examples, the stroke length of the first reciprocating needle is around 12 mm or less.

[0076] The lock stitching system 50 also includes a second reciprocating needle 14 which is configured to form the second loop 12 of the second thread 13 through the first loop 11. The second reciprocating needle 14, in the example illustrated in Figs. 1 to 13, is configured to reciprocate on a second axis 45 that is substantially perpendicular to the first axis 43 of the first reciprocating needle 8. The second reciprocating needle 14, and associated second needle assembly 37, is configured to be substantially facing the second side 9, which is Figs. 1 to 11 is below the backing material 5. The reciprocating motion includes inserting 135 second reciprocating needle 14 through the first loop 11 from a feeding side 17 of the first loop 11 to a locking side 1 of the first loop 11, wherein this motion carries a second portion 10 of the second thread 13 through the first loop 11 to the locking side 19. The reciprocating motion also includes withdrawing 137 the second reciprocating needle 14 from the first loop 11, wherein at least part of the second portion 10 of the second thread 13 is retained at the locking side 19 of the first loop 11 to form the second loop 12. In some examples, it may be advantageous for the second reciprocating needle 14 to be slender and tapered to ease insertion 135 through the first loop 11. However, since the second reciprocating needle 14 does not penetrate the backing material 5 (or any other material), this second reciprocating needle 14 can have a rounded or blunt tip. In some examples, the second reciprocating needle 14 has a diameter of less than 4mm with a stroke length of around 6mm or less.

[0077] The lock stitching system 50 may also include a support 21, as illustrated in Figs. 8 to 10, to grip at least part of the second thread to aid the second portion 10 of the second thread 13 to be retained at the locking side 19. In the illustrated example, the support 21 is located 132 at a feeding side 17 of the first loop 11 and then passing the second reciprocating needle 14 carrying the support portion 10 of the second thread 13 across or through the support 21.

[0078] In alternative examples, at least part of the support 21 may be located at the locking side 19 and in yet further examples, supports 21 may be provided at both the feeding side 17 and locking side 19 of the first loop 11. In some examples, the support 21 includes a resilient material, wherein the resilient material is configured to grip 134 at least part of the second thread 12. This can include a rubber, synthetic rubber, elastomer material.

[0079] In some examples, the support 21 includes a support aperture 24 (which can include a gap), to enable the second reciprocating needle 14 and second thread 13 to pass through the support 21. In other examples, the support 21 includes a clamping mechanism 27 to provide gripping force to the second reciprocating needle 14 and/or second thread 13 to aid retaining the second portion 10 of the second thread 13 at the locking side 19.

[0080] The lock stitching system 50 also includes a tensioner 25, as illustrated in Figs. 13 and 14, to tension 151 the first loop 11 by withdrawing at least part of the first thread 3 through the aperture 4 from the second side 9 towards the first side 7. This forms the lock stitch 1 by the first loop 11 holding the second loop 12 to the second side of the backing material 5. The tensioner 25 can include one or more rollers 53 to feed and withdraw the first thread 3. One or more of the rollers 53 may be selectively powered by a feed motor to control feeding of the first thread 3 through the aperture 4 and to withdraw the first thread 3 from the aperture 4 to tension the first loop 11. This can include selectively rotating the rollers 53 in different directions and Fig. 13 illustrates the motor 55 rotating the right hand roller 53 anti clockwise rotation to feed the first thread 3. Fig. 14 illustrates the motor 55 rotating the right hand roller 53 in a clockwise rotation to withdraw the first thread 3.

[0081] Fig. 15 illustrates an adhesive applicator 41 to apply an adhesive 23 to bond the first loop 11 to the second loop 12. This further secures the lock stitch 1 to by further preventing the first thread 3 from separating with the second thread 13. This may also prevent the first and second loops 11, 12 from changing in size (and respective tension) once bonded in place. In some examples, removing the lock stitch 1 may include shearing or otherwise cutting the adhesive 23 from the second side 9 of the backing material. The sheared adhesive would contain the second loop 12 and at least part of the first loop 11. The first threads 3 may then be separated from the backing material 5 by pulling the remaining first threads 3 out through the apertures 4. This may be useful for recycling and/or disposal purposes by separating materials that have different properties (such as the threads, backing material, and adhesives).

[0082] Subsequent lock stitches, advancing mechanism, and frame

[0083] Further features of an example of a lock stitching system 50 to form multiple lock stitches 1 will now be described. Fig. 16 illustrates a top view of the first side 7 of the backing material 5 having a plurality of lock stitch 1, G, 1”. Fig. 17 illustrates a bottom view of the opposite second side 9 of the backing material 5 with the plurality of lock stitch 1, 1’, 1” .

[0084] In this example system 50, there is provided an advancing mechanism 31 (various examples of which are described in further detail below) to selectively advance 160 the backing material 5 relative to the first reciprocating needle and the second reciprocating needle 14 to enable a specified displacement between the aperture 4 of the lock stitch 1 and the subsequent aperture 4’ of the subsequent lock stitch G. [0085] This relative displacement enables the first reciprocating needle 8 to form a subsequent first loop 1 G of the first thread 3 by piercing a subsequent aperture 4’ in the backing material 5 from the first side 7 to the opposite second side 9 of the backing material, wherein the first reciprocating needle 8 carries and passes a subsequent first portion T of the first thread 3 from the first side 7 to the second side 9. The first reciprocating needle 8 is further configured to withdraw from the second aperture 4’ wherein at least part of the subsequent first portion T of the first thread 3 is retained proximal to the second side 9 to form the subsequent first loop 1 G.

[0086] The second reciprocating needle 14 is configured to pass at least part of a subsequent second loop 12’ of the second thread 13 through the subsequent first loop 1 G. This can include inserting the second reciprocating needle 14 through the subsequent first loop 1 G from the feeding side 17 of the subsequent first loop 1 G to the locking side 19 of the subsequent first loop 1 G. Similar to forming the first stitch 1, the second needle 14 carries a subsequent second portion 10’ of the second thread 13 through the subsequent first loop 1 G to the locking side 19. The second reciprocating needle 14 is also configured to withdraw from the subsequent first loop IV, wherein at least part of the subsequent second portion 10’ of the second thread is retained at the locking side 19 of the subsequent first loop to form the subsequent second loop 12’.

[0087] The example system 50 is also configured for the thread tensioner 25 to tension the subsequent first loop 1 G by withdrawing at least part of the first thread 3 through the subsequent aperture 4’ from the second side 9 towards the first side 7. Thus the subsequent lock stitch G is formed by the subsequent first loop 1 G holding the subsequent second loop 12’ to the second side 9 of the backing material 5.

[0088] It is appreciated that this can be repeated again to form additional lock stitches 1”, 1

[0089] Moving frame 33 and fixed first and second needle assemblies 35, 37

[0090] Figs. 18 to 21 illustrate and advancing mechanism 31 for the lock stitching system 50 that includes a movable frame 33 to support the backing material 5. The backing material 5 can be, at least temporarily, fixed relative to the movable frame 33 which is the case for Figs. 18 to 21.

[0091] A first needle assembly 35 of the first reciprocating needle 8 and a second needle assembly 37 of the second reciprocating needle 14 are configured at respective positions at a first plane 36. In this example, the first needle assembly 35 and second needle assembly 37 are fixed to a stationary support 39.

[0092] The advancing mechanism 31 involves moving the frame 33 to advance the backing material across the first plane 36 so that the fixed first and second reciprocating needles 8, 14 can create lock stiches 1, G at respective locations on the backing material 5.

[0093] At Figs. 18 and 19, the frame 33 is at position XI, Y1 to enable the first reciprocating needle 8 to pierce an aperture 4 in the backing material 5 and form the first loop 11. In conjunction with the second reciprocating needle 14 and tensioner 25 a first lock stitch 1 is formed at the aperture 4.

[0094] At Figs. 20 and 21, the movable frame 33 is moved to position X2, Y2. The relative movement of the first and second needle assemblies 35, 37, enables the subsequent lock stitch G to be formed at subsequent aperture 4’.

[0095] Fixed frame 33 and moving first and second needle assemblies 35, 37

[0096] In alternative examples, the converse to the advancing mechanism 31 can be used to form multiple lock stitches 1, 1’. That is, having a fixed frame 33 to support the backing material 3 and having the first and second needle assemblies 35, 37 moving relative to the fixed frame 33.

[0097] The fixed frame 33 may be configured to support at least a portion of the backing material 5 on a second plane. The first needle assembly 35 (carrying the first reciprocating needle 8) and the second needle assembly 37 (carrying the second reciprocating needle 8) are selectively movable relative to the second plane by the advancing mechanism 31. This can include actuators that move the first and second needle assemblies in a plotter-like movement in an X and Y axis across the second plane. This enables the specified displacement between the aperture 4 and subsequent apertures 4’ to form multiple lock stitches. [0098] Advancing mechanism that conveys backing material for the needle assemblies

[0099] In yet another example, the backing material may be fed through, and between, the first and second needle assemblies 35, 37 to create multiple lock stitches 1, G. In some examples, this may include a feed mechanism to feed material across needles similar to those used in mechanical sewing machines.

[0100] In some examples, the first needle assembly 35 and the second needle assembly 37 are configured at respective positions on a first plane. The advancing mechanism 31 then conveys the backing material 5 across the first plane 36 to enable the multiple lock stitches to be formed at respective locations and apertures on the backing material 5.

[0101] In some examples, the advancing mechanism 31 can include feed dogs of a drop feed mechanism to move the backing material 5. In other examples, the advancing mechanism 31 may include conveyer belt(s) or roller(s) to move the backing material 5 across the first plane.

[0102] In some examples the respective positions of the first needle assembly 35 and the second needle assembly 37 are selectively movable on the first plane 36. That is, both the needle assemblies 35, 37 and the backing material 5 are selectively (and independently) movable. In one example, this may include feeding the backing material 5 in a Y direction through the first plane 36, whilst moving the needle assemblies 35, 37 across in an perpendicular X direction across the first plane 36. This can give additional degrees of freedom and movement to create more complex patterns of stitches.

[0103] In some examples, the backing material 5 is stored in a roll, and portions of the roll of backing material 5 are fed across the first plane 36 for lock stitches to be formed.

[0104] Horizontal and vertical configurations of the second loop 12

[0105] Figs. 22 to 24 illustrate a lock stitch 1 where the second loop 12 is configured so that the second loop 12 is substantially flush with the second side 9 of the backing material 5. As illustrated in Fig. 22, portions of the first thread 13 are side by side as they pass through the first loop 11. This results in a second loop 12 that, as illustrated in Figs. 22 to 23, configured in a substantially horizontal configuration. [0106] Figs. 25 to 27 illustrate a lock stitch where the second loop 12 is configured so that the second loop 12 has a first portion 61 of the second thread 13 in contact with the second side 9 of the backing material 5. A second portion 63 of the second thread 13 is located to be in contact with the first portion 61 of the second thread 13. As illustrated in Figs. 25 and 26, as the first loop 11 is tensioned, this pulls the second portion 63 against the first portion 61 and, in turn, the first portion 61 is pulled towards the second side 9. As illustrated in Figs. 25 and 26, this results in a second loop 12 that is configured in a substantially vertical configuration.

[0107] Applications

[0108] The lock stich system 50 and method 100 can have a variety of applications where lock stitches are required. This can include the textile industry for clothes. This can also include commercial and residential applications such as carpets, rugs, curtains, and other building materials. In some examples, this may include manufacturing of tufts for carpets. In other examples, this can include lock stitching an ornamental pattern for carpets. Other applications include furnishings that include composites that may include furniture such as sofas, chairs, etc. In additional examples, the lock stitch may be used to secure layers of fibre together for composite materials, such as fibre reinforced plastics. The present disclosure may have other general applications where sewing machines are used.

[0109] In the illustrated example, the backing material 5 is illustrated as a single layer. However, it is to be appreciated that the backing material 5 can include multiple layers. The lock stitch may be used, at least in part, to hold multiple layers of the backing material 5 to each other.

[0110] Variation - Lock stitch with single loop

[0111] Another variation of forming a lock stitch 1 will now be described with reference to Figs. 28 to 33. In this variation, only the first loop 11 is formed and the second loop 12 is substituted with a second portion 71 of the second thread 13. The second portion 71 can be a relatively short section of thread that is held against the second side 9 of the backing material by the tensioned first loop 11. [0112] Referring to Fig. 33, the method (200) of forming this alternative lock stitch 1 includes passing 111 a first portion 2 of a first thread through an aperture 4 in the backing material from a first side of the backing material to an opposite second side 9 of the backing material 5. The method then includes forming 121 a first loop 11, proximal to the second side 9, with the first portion 2 of the first thread. This can be achieved with a first reciprocating needle 8 to pierce and withdraw from the aperture 4 as described in earlier examples.

[0113] The method also includes passing 191 a second portion 71 of a second thread 13 through the first loop 11. In some examples, this includes feeding the second portion 71 of the second thread 13 through a lumen 75 of a feeder 77 and through the first loop 11 as illustrated in Fig. 28. The second portion 71 is supported in the first loop 11, at least in part, by the feeder 77.

[0114] The method further includes tensioning 151 the first loop 11 by withdrawing at least part of the first thread 3 through the aperture 4 from the second side 9 towards the first side 7, This can include using a thread tensioner 25 as described in earlier examples to withdraw part of the first thread 3. The result is to tighten the second portion 71 against the second side 9 of the backing material 5 so that the second portion 71 can be retained in that position.

[0115] The method further includes severing 195 the second portion 71 of the second thread from a remainder portion 73 of the second thread 13 as illustrated in Fig. 29. This can be achieved with a cutter 79 to sever the second portion 71 from the remainder portion 73 of the second thread at the feeder.

[0116] The result is a lock stitch 1 as illustrated in Figs. 30 to 32 where the first loop 11 holds the severed second portion 71 to the second side 9 of the backing material 5. It is to be appreciated that additional stitches can be formed at respective subsequent apertures. This can include subsequent first loops IF that are part of a continuous first thread 3, whilst, the respective second portions 71 are separate severed segments.

[0117] Advantages

[0118] Examples of the present disclosure may reduce, or ameliorate, problems with existing sewing machines. These problem can include the following. [0119] Needle stroke length

[0120] Current generation lock stitch sewing machines require that the stroke of the top needle is long enough to penetrate the thickness of the backing material and create a loop large enough for a bobbin holder to pass through: this ranges from 25mm to 35mm. This long needle stroke engenders several problems: a. The length of top thread in the open top thread loop, now containing the bottom thread, needs to be upwardly tensioned to close the loop and grip the bottom thread against the backing material. This requires that the length of the top thread to be retrieved above the backing material surface equates to approximately twice the needle penetration depth - 50mm to 70mm. This is a considerable length of thread put under stress as it is dragged back through the backing material and this leads to thread breakages, particularly with weak thread b. Column strength of the top needle depends on the thickness and length of the needle such that the longer the stroke the thicker the needle so that it doesn’t break as it continuously penetrates the backing at speeds up to 5,500 rpm. The needle also bends to a degree as it penetrates the backing and is a critical element in the dynamic performance of a machine, where failure often leads to needle breakage. This also occurs with variability in thickness and hardness of backing materials.

[0121] Examples of the present disclosure may achieve lock stitches with shorter stroke lengths.

[0122] Reduced machine Complexity

[0123] Known lock stitch sewing machines are complex machines built from over 40 manufactured component parts. Mass production of the numerous component parts has made lock stitch sewing machine affordable for consumers however with the number of moving and wearing parts maintenance and spare parts are essential to machine performance and life. The machine configuration mainly includes five subsystems, all driven by a single electric motor: feeding mechanism: needle bar mechanism; looper mechanism; shearing mechanism and adjusting mechanism, all with many moving parts. This complexity leads to the following problems: a. The various subsystems main consists of linkage mechanisms connected by revolute joints and translational joints, with joint clearances and crankshaft flexibility important factors affecting dynamic performance. This requires high quality materials and precise component manufacture, both of which are significant cost factors. b. Assembly of the different subsystems and integrating them into a finished machine, is labour intensive and time consuming c. Each joint and moving part is subject to frictional power losses so that the amount of power provided by the single drive motor is dissipated amongst the various subassemblies. This in turn leads to increased machine power consumption to make up for the cumulative frictional power losses.

[0124] Examples of the present disclosure may provide a lock stitching system with reduced complexity and parts.

[0125] Reduced mechanical linkage between Subsystem Mechanisms

[0126] In many known sewing machines, a single electric motor is used to drive the numerous mechanisms within a lock stitch machine such that they are all mechanically linked to the motor drive shaft. The needle bar mechanism and the looper mechanism need to be vertically co-located and synchronized in operation such that their drive shaft lengths need to be matched and this determines the depth of the sewing machine. That is, the length of straight lines of stitching. Domestic sewing machines have a small depth, industrial machines greater depth and special long arm sewing machines are used in certain applications such as quilting. This is a significant limitation for sewing large areas of material.

[0127] Examples of the present disclosure may reduce the reliance on mechanical linkages. In some examples, the first reciprocating needle 8 and the second reciprocating needle 14 are independently actuated by respective actuators in the first and second needle assemblies 35, 37. Furthermore, reduced components reduce the need for complex mechanical linkages. [0128] Reduced machine size, weight and power requirements

[0129] The force for a sewing needle to penetrate a normal range of textile fabrics ranges from 2 Newtons to 6 Newtons, i.e. around 0.2 kg to 0.6 kg of force. A high speed industrial sewing machine typically has a footprint of 517mm x 178mm, weighs up to 40kg, operates at speeds up to 5,000 rpm is powered by a 400 watt servo motor and consumes 520VA of power. The equivalent home industrial sewing machine has a footprint of 450mm x 220mm, weights around 18 kg, operates at speeds up to 1,500 rpm and consumes around 170VA of power. Assuming that the power factor for needle penetration is 0.5, that is needle penetration occupies only half of the power cycle, then energy required for needle penetration in industrial sewing machines is only half of the total energy consumed in sewing. Overall, relative to the magnitude of sewing needle penetration forces, current lock stitch sewing machines consume considerable resources in their manufacture, occupy a quantifiably large amount of space and consumer considerable power to carry out sewing operations.

[0130] Example of the present disclosure may provide reduced size, weight and power consumption.

[0131] Increased thread capacity

[0132] In known sewing machines, the top thread is supplied in cones that have enough thread length capacity for continuous sewing. However, whenever the bottom thread in a bobbin is exhausted it is necessary to stop sewing, replace the bobbin with a new one loaded with bottom thread, and rethread the machine before resuming sewing operations. In stitch intensive sewing operations, such as embroidery, machine manufacturers have developed complex and expensive bobbin changes that reduce the machine downtime but that does not eliminate the problem of machine stoppage. This is an important consideration for fully robotic sewing system requiring unattended operation to reduce labour costs, as is currently in development for automated manufacture of T Shirts. The sewing industry has dreamt for many years of an “endless bobbin”.

[0133] Examples of the present disclosure does not require a bottom bobbin that is constrained by size for the bobbin to pass through loops (as required in known sewing machines). Therefore the second thread 13 of the present disclosure can be supplied from a larger reel that, in practice, is of unlimited length. This can reduce the downtime of the machine as a reel sufficient for an entire work shift could be used with examples of the disclosed system.

[0134] Mobility of components

[0135] Known lock stitch sewing machines are bulky and their physical dimensions are constrained as noted above and in these circumstances sewing operations are carried out by moving material through a stationary machine. This is very inconvenient and labour intensive when sewing large textile products such as composite carbon fibre structures, quilts, large sewn and embroidered panels. In the case of embroidery machines with multiple stationary embroidery heads it necessitates moving an embroidery frame holding the backing material, by using use powerful servo motor systems with motion control systems to achieve maximum embroidery speeds.

[0136] The present disclosure enables use of relatively smaller first and second needle assemblies 35, 37. This enables, in some examples, selectively movable first and second needle assemblies 35, 37 that allow flexibility and additional degrees of freedom for lock stitching. This may also reduce the reliance on large powerful servo motor systems to move frames as noted above.

[0137] Security of the lock stitch

[0138] In some examples, backing materials that are sewn together may compress or shrink and the lock stitches may no longer hold the structure together. With applications such as embroidery it is often necessary to fuse an adhesive layer material to the bottom threads to bond the locked compound joints from unravelling. This involves applying sheets of material across the whole underside of the backing material which is wasteful when it is only the locked compound joints that need bonding.

[0139] Examples of the present disclosure selectively apply adhesive to the first loop 11 and the second loop 12 that may reduce waste of adhesives.

[0140] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.