AU2005100369A4 - Stitching Machine - Google Patents

Description

004378456 1 STITCHING MACHINE Field of the Invention This invention relates to a stitching machine, and is particularly concerned with providing a machine for stitching heavy duty materials. In a separate aspect, the invention is directed to a novel stitched assembly.

Background Art In one type of known stitching machine which is used for stitching end pieces of a heavy duty material to form an end loop in the material, a length of material, doubled over at its end is clamped between clamping plates which form part of a movable carriage. Movement of the carriage is controlled in both the longitudinal and transverse directions of the length of material to be stitched.

However, the stitching takes place within an opening in the upper clamping plate and this imposes limitations on the area that can be stitched by such an electronic stitching machine without undoing the clamp, moving the material and reclamping the material in a different position.

One form of this known type of stitching machine uses a stepped cam with a number of depressions around its periphery to control the movement of the carriage when the stitching needle is moving in and out of the material. The number of depressions in the peripheral surface of the cam correspond to the number of stitches in the stitching cycle, and it is not possible to vary the number of stitches without replacement of the cam.

This latter limitation has been addressed by employing a heart-shaped stepper cam rather than one with peripheral depressions. In an electronic digital adaptation of the machine, the cams are replaced by servo-controlled pneumatic drivers, but in both these cases there remain the disadvantages inherent in the clamping plate configuration.

It is an object of the invention to at least in part alleviate those disadvantages.

004378456 2 Summary of the Invention According to one aspect of the invention, there is provided a stitching machine comprising: a reciprocally movable stitching needle; an elongate platform for supporting a length of material to be stitched; a first drive arrangement for moving the platform relative to the stitching needle in a transverse direction extending transversely to the length of material; material engaging means for engaging the length of material on the platform; a second drive arrangement for moving the material engaging means to move the length of material relative to the platform and stitching needle in a longitudinal direction extending longitudinally of the length of material.

The material engaging means preferably comprises at least one roller having gripping means adapted to engage the material and to move the material along the platform in the longitudinal direction when the at least one roller is rotated.

Preferably, the first and second drive arrangements are mechanical drive arrangements. The drive arrangements are preferably synchronised so that the stitching machine can make a stitching pattern comprising a line of stitches in one direction (eg. when the first drive arrangement is operating to drive the platform in the transverse direction) joined by stitches at the ends of the lines of stitches in the other direction (eg. when the second drive arrangement is operating to move the length of material in the longitudinal direction).

The stitching needle is preferably reciprocally movable in a substantially vertical direction with the platform for supporting the material extending substantially horizontally. The drive means for reciprocating the needle is 004378456 3 preferably synchronised with the first and second drive arrangements so that when the material is being moved relative to the stitching needle in either the transverse direction or the longitudinal direction, the needle is out of the material.

In a particularly preferred embodiment, the first and second mechanical drive arrangements are driven from the drive means for reciprocating the stitching needle. This may be achieved by providing an eccentric arrangement on a drive shaft of the reciprocating drive means, and using the eccentric movement of the connecting cam shaft to drive independent gear arrangements for driving of the first and second drive arrangements independently, but in a synchronised manner.

The drive from the eccentric on the drive shaft of the reciprocating drive means is preferably transmitted to the first and second drive arrangements via clutch means which is arranged to ensure that no drive is transmitted to the first and second drive arrangements during half of the rotation of the drive shaft when the needle is in the material. The clutch means is preferably in the form of a first sprag clutch.

In one preferred embodiment the first drive arrangement includes a rotatable first cam, a pivoting arm having a cam follower movable in a cam track of the first cam and a connecting rod connected to the pivoting arm at one end and attached to part of the platform at its other end for reciprocating the platform in the transverse direction. The platform preferably includes a carriage member which is movable on a linear bearing in the transverse direction.

The second drive arrangement preferably includes a rotatable second cam, connected via a number of linkage members and a clutch means to the drive shaft of said at least one roller for engaging the material and moving the material in the longitudinal direction relative to the platform and needle. The clutch means is preferably arranged to transmit drive to the at least one roller to move the material longitudinally only when the platform has reached an end of its travel when reciprocating in the transverse direction. The clutch means of the second drive arrangement preferably comprises a second sprag clutch.

004378456 4 The first and second cams of the first and second drive arrangements are preferably harmonic cams, ie. they have smooth cam tracks in contrast to cams of prior art stitching machines which have a plurality of depressions or indentations in their cam tracks corresponding to the number of stitches to be made. In a preferred embodiment, the first cam has a generally heart-shaped cam track and the second cam has a cam track shaped like a teardrop having a semi-circular head part and smooth curved parts extending from the head part to a pointed opposite end of the cam track.

The stitching machine preferably includes means arranged to stop the machine upon completion of a stitching pattern. In one preferred arrangement, the stopping means includes a toothed wheel which rotates during operation of the first drive means for the needle when the toothed wheel has rotated by a predetermined amount. The machine may also include means for moving the needle out of the workpiece when the drive means is stopped, eg. a servoassisted needle positioner.

In a second aspect, the invention provides an assembly of two lengths of woven fabric segment each having a weft and a warp, wherein the warp in each fabric segment extends longitudinally of the respective fabric segment, and wherein the fabric segments are stitched together by stitching that includes elongate lines of stitches extending transversely across the warp of the fabric.

Brief Description of the Drawings The present invention will now be described in greater detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a piece of a heavy duty material showing a conventional stitching pattern produced by a number of known types of stitching machine; Figure 2 is a section on the line 2-2 in Figure 1; 004378456 Figure 3 is a plan view of an end piece of a heavy duty material showing a stitching pattern produced by a stitching machine in accordance with the invention; Figure 4 is a section on the line 4-4 of Figure 3; Figure 5 is a schematic perspective view of a known type of conventional stitching machine; Figure 6a and 6b show a plan view of a cam of a prior art stitching machine such as that shown in Figure 5, and corresponding movement of the stitching needle; Figure 7 is a perspective view of a stitching machine in accordance with an embodiment of the invention; Figure 8 is another perspective view of the stitching machine of Figure 7; Figure 9 is a side view of the stitching machine of Figure 7; Figure 10 is an end view of the stitching machine of Figure 7; Figure 11 is a plan view of the stitching machine of Figure 7; Figure 12 is a schematic perspective view of the drive arrangements for the stitching machine of Figure 7; Figure 13 is a plan view of a first cam of the stitching machine; Figure 14 is a plan view of a second cam of the stitching machine.

Description of Embodiments of the Invention Referring to Figures 1 and 2, there is shown a length of heavy duty material such as canvas, or a polyester strip, which has an end portion 12 folded over the main part 14 of the length of material to form a loop 16. The end portion 12 is 004378456 6 secured to the main part 14 by lines of longitudinal stitches 18 extending along the length of the material 10 which usually corresponds to the warp of the material When stitched, the length of heavy duty material has a multitude of applications, for example as a cargo sling or in other applications where a high degree of strength is required, not only in the main part 14 of the material 10, but also in the end loop 16.

Figure 5 is a schematic view showing a prior art stitching machine 20 for producing stitching 18 of the kind shown in Figures 1 and 2. The stitching machine has upper and lower clamping plates 21,22 forming part of a movable carriage 24. The clamping plates 21,22 are adapted to clamp part of a length of heavy duty material 10 so that a stitching operation can be performed by a vertically movable stitching needle 26 in the area within a rectangular central opening 28 in the upper clamping plate 21.

As shown schematically in Figure 5, the longitudinal clamping plates 21, 22 and carriage 24 are movable in transverse directions of the length of material by respective connecting rods 30, 32 and stepped cams 34,36, with movement of the cams 34,36 being mechanically controlled.

The stepped cam 34 for producing the longitudinal movement of the carriage is shown in plan view in Figure 6. The cam 34 is rotatable about an eccentric axis 40 and has a number of depressions 42 in its peripheral cam surface 44. The depressions 42 are spaced around the cam surface 44 so that the cam follower 46 at one end of connecting rod 30 is located in one of the depressions 42 when the needle 26 is at its lowermost point for stitching and the cam follower 46 is located midway between two adjacent depressions 42 when the needle 26 is at its uppermost position during stitching. Thus, the shaded segments S in Figure 6a correspond to downward movement of the stitching needle 26 and the unshaded segments U correspond to upward movement of the stitching needle 26, as shown in Figure 6b.

In order to produce the stitching pattern of Figure 1, the cam 34 is operated to move the carriage 24 in the longitudinal direction of the length of material 004378456 7 and a number of longitudinal stitches are made corresponding to the number of depressions 42 around half the periphery of the cam 34. The other cam 36 is then rotated by the amount of one depression so that the connecting rod 32 moves the carriage 24 in the transverse direction of the material 10 and the needle 26 produces one transverse stitch 19. The cam 34 then continues rotating to move the carriage 24 longitudinally in the opposite direction and the needle 26 produces the same number of longitudinal stitches as the number of depressions 42 around the other half of the periphery of the cam 34. The process continues until the carriage has moved transversely by an amount corresponding to the lateral width of the rectangular opening 28 in the upper clamping plate 21.

An electronically controlled stitching machine can be programmed to produce different stitching patterns, eg. by digitally controlling movement of clamping plates 21, 22 or by employing digitally driven pneumatic actuators in place of the cams. However, the maximum length and width of the stitching pattern is limited by the size of the rectangular aperture 28 in the upper clamping plate 21. It is often desired to provide a stitching pattern over a longer length of the material 10 than the longitudinal dimension of the aperture 28 in the clamping plate 21. This requires the operator to unclamp the material, move the length of material 10 and reclamp the material in a position corresponding to the position where the last stitching finished, which can be inconvenient and time consuming.

Also, a break in the stitching pattern can cause weaknesses in the stitched end of material forming the loop.

Referring to Figures 7 to 12 there is shown a stitching machine 100 in accordance with a preferred embodiment of the invention. The stitching machine 100 has material supporting means in the form of an elongate platform 102 for supporting a length of material 110 to be stitched. A stitching needle 104 is reciprocally movable in a substantially vertical direction by a drive motor (not shown) contained within a housing 106. The machine further has material engaging means 107 for engaging and moving the length of material 110 on the platform 102 in the longitudinal direction of the material 110, a first drive arrangement 108 for moving the platform 102 and material 110 and the material engaging means 107 relative to the stitching needle 104 in a transverse 004378456 8 direction, and a second drive arrangement 109 for driving the material engaging means 107 to move the material 110 in the longitudinal direction of the length of the material 110.

The elongate platform 102 is generally U-shaped having a base 120 and side walls 122,124 extending longitudinally along the side of the base 120. The platform 102 has a transversely extending carriage member 126 at one end which is slidably mounted on a linear bearing 127 fixed to a base plate 101 of the apparatus. The other end of the platform 102 is provided with a wheel 128 which rolls on the base plate to allow the platform 102 to move in a transverse direction relative to the base plate 101. The platform base 120 may be wider than the usual width of heavy duty materials requiring stitching, eg. a polyester strip for a cargo sling. This allows materials 110 of different widths to be accommodated on the platform with one or more spacer inserts 125 (Figure 11) being provided when a material 110 of lesser width than the platform base 120 is to be stitched.

The material engaging means 107 comprises a pair of upper and lower rollers 130,132 each having a plurality of circumferential raised gripping portions 134 spaced along the length of the rollers 130,132. The raised gripping portions 134 are provided with teeth 136 (Figures 9 and 10) adapted to dig into the material 110. In order for the teeth 136 of the lower roller 131 to engage and grip the material 110, the platform base 120 has an opening 121 (Figures 8 and 11) in the region of the rollers 130,132.

Each roller 130,132 is mounted for rotation with a drive shaft 140,142 which forms part of the second drive arrangement 109. Each roller 130,132 is also movable along its respective drive shaft 140,142. As best seen in Figures 9 and 10, this is achieved by providing longitudinally extending keyways 144 in the peripheral surfaces of the drive shafts 140,142 in which complementary shaped keys 138 provided on the internal axial bores 139 of the rollers 130,132. Thus, the rollers 130,132 can move axially along their respective drive shafts 140,142 to allow the platform 102 and the material 110 to move laterally relative to the needle 104, but when the drive shafts 140,142 are rotated, the rollers 130,132 rotate with 004378456 9 the drive shafts 140,142 to move the material 110 longitudinally along the platform 102.

The first drive arrangement 108 for moving the platform laterally includes a first cam 150, a pivoting arm 152 which has a cam follower 153 at one end movable in a smooth cam track 151 that extends about the periphery of the first cam 150, a connecting rod 154 attached at one end to the pivoting arm 152 at an intermediate position along its length, and an attachment member in the form of an angle piece 156 attached to the other end of the connecting rod 152. The angle piece 156 has a horizontally extending portion 157 attached to said other end of the connecting rod 152 and a vertically extending portion 158 fixed to the side wall 122 of the platform 102. In order to accommodate different stitching widths, arm 152 has a number of spaced holes 159 defining respective selectable positions at which rod 54 can be pinned to the arm, each position defining a different stitching width.

The first cam 150 is generally heart-shaped and therefore only has one depression 160 in its peripheral surface provided at the head 161 of the heartshaped cam track 151 and diametrically opposed from the point 162 of the heartshaped track 151. Thus, the cam track 151 is divided into two halves 163,164 (Figures 11 and 12). The cam 150 is eccentrically mounted on a first rotatable cam shaft 166 at a position closer to the head of the heart-shaped track 151, so that when the shaft 166 and cam 150 are rotated and the cam follower 154 moves along one half 163 of the cam track 151, the first drive arrangement 108 causes the platform 102 and the material 110 to move transversely in one direction relative to the needle 104. When the cam follower 154 moves along the other half 164 of the cam track 151 the drive arrangement 108 causes the platform 102 to move in the reverse direction, thereby reversing the direction of transverse movement of the material 110 relative to the needle 104.

As most clearly seen in Figure 12, the second drive arrangement 109 for rotating the rollers 130,132 to move the length of material in the longitudinal direction includes a second cam 170 and a connecting rod 172 which has a cam follower 174 at one end 173 movable in a cam track 171 of the second cam 170.

004378456 The other end 175 of the connecting rod 172 is pivotally mounted on a post 176 to the base plate 101 of the apparatus. The second drive arrangement 109 also includes a longitudinally movable member 180, a vertically extending member 184, a sprag clutch 186, and a pair of gears 200,202 respectively mounted on the drive shafts 140,142 for the rollers 130,132.

The second cam 170 is generally teardrop-shaped so as to define a smooth cam track 171 extending around its periphery. The cam track 171 has a semicircular end part 193 and two curved parts 195,196 extending between the semicircular end part 193 and a pointed end 194 diametrically opposed to the semicircular end part 193. The cam 170 is eccentrically and rotatably mounted on the rotatable cam shaft 166 at a position closer to the semi-circular end part 193 of the cam track 171, but does not rotate with shaft 166.

The longitudinally movable member 180 has one end 181 connected to a mounting plate 178 provided on the connecting rod 172 at an intermediate location along its length. The other end 182 of the longitudinally movable member 180 is pivotally connected to the lower end 183 of the vertically extending member 184, the upper end 185 of which is connected via the sprag clutch 186 to the drive shaft 142 for the lower roller 132.

As the second cam 170 rotates, movement of the cam follower 174 in the cam track causes the connecting rod 172 to pivot on a vertical axis about its pivotal mounting 176. This pivotal movement is translated to longitudinal movement of the longitudinally movable member 180 which is in turn rotated into pivotal movement of the vertically extending member 184 and then to rotational movement of the drive shaft 142 under the control of the sprag clutch 186. The gears 200,202 are engageable with each other so that rotation of the lower gear 202 and the drive shaft 142 for the lower roller 132 causes the upper gear 200 and drive shaft 140 for the upper roller 130 to rotate in the opposite direction. Rotation of the upper and lower rollers 130,132 in this manner causes the length of material 110 to move along the platform 102 in a longitudinal direction.

004378456 11 The drive motor for reciprocating the stitching needle 104 is also used to rotate the cams 150,170 of the first and second drive arrangements 108,109 for moving the material 110 in the longitudinal and transverse directions relative to the needle 104. A drive shaft 210 from the drive extends out of the end 211 of the motor housing 106 remote from the needle 104. A connecting rod 212 is connected at one end 213 to an eccentric mounting 216 on the drive shaft 210.

The other end 214 of the connecting rod 212 is connected via a crank arm 218 and sprag clutch 220 to a rotatable shaft 222. The shaft 222 is rotatable about a vertical axis and is adapted to drive the first cam shaft 166 and cam 170 via first and second drive belts or chain sprockets 226,228 respectively. The first drive belt 226 extends around a toothed wheel or sprockets 167 mounted on the first cam shaft 166 and an upper sprocket 227 mounted on the rotatable shaft 222. The second drive belt 228 extends around a toothed wheel or sprocket 169 fixed to cam 170 and a lower sprocket 229 mounted on the rotatable shaft 222. Cam 170 and sprocket 169 rotate as a unit on shaft 166, but are not keyed to the shaft.

The sprockets 167,169 on the cam shaft 166 and the upper sprocket 227 on the rotatable shaft 222 are of equal size. However, the lower sprocket 229 on the rotatable shaft 222 has a diameter which is twice the diameter of the upper sprocket 227. Thus, when the shaft 222 rotates, the cam 170 revolves freely on shaft 166 at twice the speed of the cam shaft 166 and the first cam 150 of the transverse drive arrangement.

The sprag clutch 220 on the rotatable shaft 222 is arranged to rotate the shaft 222 only during half of each revolution of the drive shaft 210 when the connecting rod 212 is moving in one direction. When the connecting rod 212 moves in the opposite direction in the other half of the revolution of the drive shaft 210, the sprag clutch 220 is racking, so that no rotation is transmitted to the shaft 222. The sprag clutch 220 is therefore able to ensure that the needle 104 is out of the material 110 when the platform 102 is moving in the transverse direction relative to the needle 104.

Figures 3 and 4 show a length of heavy duty material 110 with a typical stitching pattern which can be produced by the stitching machine 100 of the 004378456 12 invention. The material 110 is similar to that of Figures 1 and 2 in that it has an end portion 112 folded over the main part 114 of the material 110 to form a loop 116. However, the stitching pattern differs from that of Figures 1 and 2 in that it has lines of transversely extending stitches 117 extending across the material with each line of transverse stitches 117 joined to the next line of stitches by one or more longitudinal stitches 118.

The stitching pattern shown in Figures 3 and 4 is preferred over the pattern of Figures 1 and 2 because the warp of the material usually extends in the longitudinal direction of the length of material, and lines of stitches 117 extending transversely across the warp of the material 110 can provide a stronger join with less material than the lines of stitches 18 extending longitudinally along the warp of the material 10 in Figures 1 and 2.

A preferred method of operation of the stitching machine 100 of Figures 7 to 12 to produce the stitching pattern of Figures 3 and 4 will now be described.

A length of material 110 with its end portion 112 folded over the main part 114 to form a loop 116 is fed onto the platform 120 between the rollers 130,132.

The drive motor within housing 106 is energised so that the needle 104 carrying a thread is reciprocated in a vertical direction into and out of the material 110. As the needle 104 moves up out of the material 110, the connecting rod 212 drives the rotatable shaft 222 via the sprag clutch 220, and the first cam shaft 166 and cam 150 are rotated to move the platform 120 and material 110 in a transverse direction relative to the needle 104. During this time, although the second cam 170 is being rotated by the rotating shaft 222, the other sprag clutch 186 ensures that no drive is transmitted to the shaft 142 and rollers 130,132 when the longitudinally movable member 180 and vertically extending member 184 are moving in one direction.

When the drive shaft 210 from the drive motor has rotated through half a revolution and the needle 104 is about to re-enter the material 110 on its downward stroke, the connecting rod 212 then moves in the reverse direction and the sprag clutch 220 is then racking so that no motion is transmitted to the 004378456 13 rotatable shaft 222 or the first and second cams 150, 170. Thus when the needle 104 is in the material, the material 110 is prevented from moving in either the transverse or longitudinal direction relative to the needle 104.

The machine 100 continues operating in this manner until the cam follower 153 has reached either the pointed end 162 or the depression 160 in the head part 161 of the heart-shaped cam track 151, and the platform 102 and material 110 have reached the end of their transverse movement relative to the stitching needle 104. During this time, the cam follower 174 has been moving around the semicircular end part 193 of the second cam track 171. As shown in Figure 14 the axis of rotation of the second cam 170 is provided at the centre of the semi-circular end part 193 so that no pivotal movement is transmitted to the connecting rod 172 and consequently the rollers 130 and 132 do not rotate when the cam follower 174 is moving around the semi-circular end part 193.

As the cam follower 153 moves across either the pointed end 162 of the first cam track 151 or through the depression 150, no transverse movement is transmitted to the platform 102 through the pivoting arm 152 and the connecting rod 154. During this time, the cam follower 174 has left the semi-circular end part 193 of cam track 171 and is moving through one of the curved parts 191 towards the pointed end 194 of the cam track 171. This causes the connecting rod 172 to pivot and the member 180 to move longitudinally in one direction to pivot the vertically extending member 184 whereby rotation is transmitted via the sprag clutch 186 to the rollers 130, 132 to move the material in a longitudinal direction along the platform 102 relative to the stitching needle 104. The stitching machine is therefore able to execute one or more stitches 118 in the longitudinal direction at the end of a line of transverse stitches 117, as shown in Figures 3 and 4.

When the cam follower 174 reaches the pointed end 194 of the second cam track 171, the cam followerl53 has moved through either the pointed end 164 or the depression 160 in the head part 161 of the heart-shaped first cam track 151.

Then the cam follower 153 is moving in the opposite half of the cam track 151 so as to effect transverse movement of the platform 102 and material 110 in the reverse direction. During this time, the cam follower 174 starts moving in the 004378456 14 curved part 192 of the second cam track 171 from the pointed end 194 towards the semi-circular end part 193. Although movement is transmitted through the connecting rod 172 and the longitudinally movable member 180 to the vertically extending member 184 to pivot the member 184 in the reverse direction, the sprag clutch 186 is racking during this phase so that no rotational movement is transmitted to the rollers 130,132. Thus, the stitching machine is able to execute a line of transverse stitches 117 in the reverse direction without any movement of the material in the longitudinal direction.

The machine continues operating in the manner described above until the required number of lines of transverse stitches 117 joined at their ends by longitudinal stitches 118.

The stitching machine 100 preferably also includes an arrangement for stopping the machine upon completion of a stitching pattern. As shown in Figures 7 to 12, a jigger arm 240 extends from the end 251 of the pivoting arm 152 adjacent its pivotal mounting 250 and remote from the end 252 on which the cam follower 153 is provided. The end of the jigger arm 240 remote from the pivoting arm 152 has a hook 242 which engages with a toothed wheel 244 mounted on a rotatable shaft 246. The rotatable shaft 246 has an indentation mark 248 at a particular position on its cylindrical surface 247. A micro-switch 256 and/or optical sensor 258 is positioned adjacent the rotatable shaft 246 for activating a solenoid (not shown) to stop the main drive motor of the machine 100 when the indentation mark 248 on the rotatable shaft 246 passes the optical sensor 258.

The jigger arm 240 is arranged to rotate the toothed wheel 244 by one tooth width for each revolution of the cam 150 when the cam follower 153 is moving in one half of the cam track 151 of the first cam 150. As each revolution of the drive shaft 210 corresponds to one stitch, the toothed wheel 244 is indexed by one tooth for each transverse stitch 117 in one direction. When the cam follower 153 is moving in the other half of the cam track 151, no rotation of the toothed wheel takes place.

004378456 In one particular preferred embodiment, the stitching machine is arranged to complete six transverse stitches 117 in each transverse direction and the toothed wheel 244 has 24 teeth so that the stitching machine 100 can complete four rows of transverse stitches 117 in each transverse direction in the stitching pattern of Figures 3 and 4.

It will, however, be appreciated that the number of stitches in a transverse line of stitches 11 may be altered by increasing or decreasing the amount of movement provided by cam 150 in one revolution of shaft 210. The total number of stitches in a stitching pattern may be varied by replacing the toothed wheel 244 with another toothed wheel having a different number of teeth, eg. 24,26. Also, the total number of stitches could be varied by providing a plurality of indentation marks 240 on the rotatable shaft 246.

When a stitching pattern has been completed, it is desirable to stop the machine with the needle 104 out of material 110. This may be achieved by providing a servo motor (not shown) in addition to the main drive motor. The servo motor is arranged to idle during normal operation of the stitching machine 100, but upon completion of a stitching pattern, when the main drive motor is stopped, the servo motor is activated to rotate the drive shaft 210 by part of a revolution to raise the stitching needle 104 out of the length of material 110. The micro-switch 256 which is arranged to switch off the main drive motor may also be used to switch on another circuit for activating the servo motor. A second switch (not shown) which senses when the drive shaft 210 has rotated by a sufficient amount to raise the needle 104 out of the material is provided to switch off the servo motor.

The machine or stitching speed of the machine does not change when adjustments are made at point 216 or 218, but the speed of the attachment does.

The ratio of revolutions of shaft 210 to shafts 222, 166 can be varied from say 8 revolutions on shaft 210 to give one revolution on shaft 222 or up to 50-60 revolutions to give one revolution on 222. This results in 50-60 stitches in one revolution of cam 150. Therefore, the speed of the attachment decides the number of stitches in a cycle. For instance, if the machine is stitching at say 500 stitches per minute and the attachment is adjusted to give one revolution on shaft 222 for 004378456 16 revolutions on shaft 210, that translates to 50 stitches while the cam on shaft 222 gives one cycle and one index on counting sprocket 244. If we increase the movement on rod 212 to give one revolution to five revolutions on shaft 210. One cycle will take half that time, which translates to only 250 stitches in one cycle and takes 30 seconds (1/2 minute).

The electro-mechanically operated stitching machine described above has several advantages over a prior stitching machine that utilises clamping plates to hold the workpieces. As described above, an electronic stitching machine which clamps the material between clamping plates is only able to stitch a pattern over a limited area of the material, and when it is required to stitch over a larger area than the opening in the upper clamping plate, it is necessary to unclamp the material, move the material, and reclamp the material before the machine can stitch another stitching pattern in the reclamped area. In contrast, the stitching machine of the present invention can produce a stitching pattern over any required length of material without having to unclamp and reclamp a clamping means. Also, the stitching machine is able to produce a continuous stitching pattern over an extended length of material, simply by re-starting the machine at the end of a first stitching pattern, or by disabling the arrangement for stopping the machine after a certain number of stitches.

In a preferred embodiment, the bobbin case (not shown) may be located below the platform 102 and removed by means of a spring-loaded shaft having a hook on its end which is moved behind the bobbin in its case, turned through 900 and pulled back to remove the bobbin. A second moveable shaft with a magnetic tip extracts the bobbin from the case.

Another advantage of the stitching machine of the invention is that the platform is able to accommodate materials of different widths simply by the use of different sized inserts 125. Electronic stitching machines require a change of clamping plates and reprogramming to produce a stitching pattern on a material of a different width.

004378456 17 A further advantage of the electro-mechanical stitching machine of the invention is that it is easier and less expensive to service and repair than prior mechanical or digitally controlled electronic stitching machines.

It will be appreciated that various modifications and alternations may be made to the preferred embodiment described above without departing from the scope and spirit of the invention.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

It will also be understood that the term "comprises" (or its grammatical variants) as used in this specification is equivalent to the term "includes" and should not be taken as excluding the presence of other elements or features.

Claims (5)

1. A stitching machine comprising: a reciprocally movable stitching needle; an elongate platform for supporting a length of material to be stitched; a first drive arrangement for moving the platform relative to the stitching needle in a transverse direction extending transversely to the length of material; material engaging means for engaging the length of material on the platform; and a second drive arrangement for moving the material engaging means to move the length of material relative to the platform and stitching needle in a longitudinal direction extending longitudinally of the length of material.

2. A stitching machine according to claim 1, wherein the material engaging means comprises at least one roller having gripping means adapted to engage the material and to move the material along the platform in the longitudinal direction when the at least one roller is rotated.

3. A stitching machine according to claim 1 or 2, wherein the drive arrangements are synchronised so that the stitching machine can make a stitching pattern comprising a line of stitches in one direction joined by stitches at the ends of the lines of stitches in the other direction.

4. A stitching machine according to claim 1, 2 or 3, wherein the stitching needle is reciprocally movable in a substantially vertical direction with the platform for supporting the material extending substantially horizontally. 004378456 19 0

5. An assembly of two lengths of woven fabric segment each having a weft c and a warp, wherein the warp in each fabric segment extends longitudinally of the Crespective fabric segment, and wherein the fabric segments are stitched together by stitching that includes elongate lines of stitches extending transversely across the warp of the fabric. 0 5 the warp of the fabric.