WO1985002389A1

WO1985002389A1 - A cloth pick up device

Info

Publication number: WO1985002389A1
Application number: PCT/AU1984/000247
Authority: WO
Inventors: Paul Charles Wong; Robin Wei Shin Yu
Original assignee: Wong Paul C; Robin Wei Shin Yu
Priority date: 1983-11-29
Filing date: 1984-11-28
Publication date: 1985-06-06
Also published as: EP0197932A1; JPS62500021A

Abstract

An apparatus for engaging and/or picking up an elastic, porous, limp, mesh, cellular, woven or knitted workpiece, comprising at least two engagement members (15, 16) each of which carries a plurality of workpiece engaging projections (14), movement means (4, 5) to move at least one of the engagement members relative to the other member, and means (6, 7) to move the device into and out of contact with a face of the workpiece, the workpiece engaging projections (14) being such that when engaged with a workpiece and the engagement members (15, 16) are relatively moved, the projections (14) tension the workpiece therebetween and thus retain the workpiece on the engagement members (15, 16).

Description

BACKGROUND TO THE INVENTION This invention relates to apparatus for the engagement or pick-up of elastic, porous, limp, mesh, cellular, woven or knitted materials, articles or workpieces. More particularly, but not exclusively, the invention is applicable to apparatus for picking up articles or workpieces made from woven fabric, knitted sheets, and foam rubber materials to enable the article or workpiece to be positioned, manipulated, and/or transported in automatic manufacturing processes. Such an automatic manufacturing process may be found in a robotic or mechanised production line for garments or foam rubber products.

In a substantial -part of the industry, manufacturing products from material .that is elastic, porous, limp, mesh, cellular, woven or knitted, the handling of articles or workpieces made from these materials within and between processing machines is largely performed manually. Such handling activities are typically found in the garment industry where limp fabric workpieces have to be fed into sewing machines by manual operations such as picking a fabric ply off the top of a stack, the matching together of two or more fabric sheets, and the presentation of a fabric sheet into a sewing or

^•tagging machine.

Various devices have been proposed to handle (that is position, manipulate, and/or transport) these said

_L materials in order to allow these presently manual handling operations to be automated. One type of known device employs retractable annularly displaced, conically extending, needles to engage the workpiece; another uses retractable curved needles for the same purpose and yet another engages the workpiece by pinching it between inwardly closing prongs, pinching wheels, or by mechanical nipping a wave created in the workpiece to be engaged. Still others employ vacuum techniques, adhesion to a sticky surface, and the gripping of a fabric workpiece by mechanical fingers after causing it to flap appropriately by a jet of air.

These devices have been successful to a certain level, but each has disadvantages of one kind or another. For. example, many are not totally "effective at separating the top. ly from a stack; others cannot adequately control very limp workpieces allowing corners and edges to droop and sagging'to occur between engagement points, or otherwise lose control of the workpiece except at the point of engagement. The engagement of complex shapes and narrow sections in limp materials and the ability to maintain the shape and form of a limp workpiece without gross distortions are additional problems not adequately solved by known devices.

Further, many of the known pick-up devices will not handle a plurality of workpiece sizes and shapes without having to be rearranged or reconfigured. SUMMARY OF THE INVENTION

It is the object of the present invention to overcome the known problems of effectively separating, handling and controlling sheets, workpieces or articles made from elastic, porous, limp, mesh, cellular, woven, or knitted materials.

A further object of the invention is to allow adequate control of the form or flatness of the sheet or workpiece, so that operations such as accurate placement or glueing with very limp materials, can be performed with greater precision.

A further object of the invention is to provide an effective means for engaging and controlling the edges of a sheet or workpiece made of the said materials, so that it does not sag, distort, droop, or become otherwise uncontrollable or unpredictable.

A further object of the invention is to provide an effective means for engaging and retaining control of the shape and flatness of complex and narrow workpieces. (By complex is meant shapes possessing boundaries similar to that possessed by, for example, the letters "A" or "X"; by narrow workpieces is meant workpieces in which sections may have widths in the order of 10mm.) A workpiece having the shape of a grating, for example, would be complex and possess narrow sections.

A further object of the invention is to provide an apparatus for effectively handling a range of workpiece sizes and shapes without the need to perform adjustments to the apparatus.

A further object of the invention is to provide an alternative means for effectively separating the sheet or workpiece being engaged from the neighbouring sheet or workpiece, for example, in separating a single ply from a stack of plys.

A further object of the invention is to provide an alternative means for effectively disengaging a sheet or workpiece from the engagement and handling apparatus.

Although the present invention is particularly suitable to be attached to -a robot or a similar materials handling device, .so that the manual material- handling operations in garment manufacturing processes can be automated, it is equally applicable to other apparatus by which workpieces or articles consisting substantially of any of the said materials requires to be positioned, manipulated, and/or transported.

The invention provides means for engaging the workpiece(s) or article(s) made substantially from the said materials, that comprises means for generating a tension pattern in the article(s) to be engaged, and wherein the tension pattern in the said article(s) in turn creates firstly, a mechanical and/or frictional holding force between the said article(s) and the apparatus, and secondly, a distortion pattern in the said article(s) which is manifest as a pattern of relative movement between the article(s) being engaged and adjacent article(s), if any. 5 In the following, a number of preferred, but not necessarily exhaustive, forms of the invention are described. In the descriptions and claims, by the terms article(s) or workpiece(s) is meant discrete sheet(s) or part(s) of a continuous filament or roll,

10 or discrete article(s) or part(s) of a larger article, made (or substantially made) from elastic, porous, limp, mesh, cellular, woven, or knitted materials.

The first form of the invention comprises means for generating the said tension pattern in a

15. multiplicity of localities • distributed over that surface area (or a substantial part of the area) of the workpiece that is being engaged. In this manner, the positions of application of the workpiece holding force is distributed over the engaged surface rather than at

20 a few discrete positions on the workpiece. (The level of distribution, or the proximity of adjacent engagement points within a matrix, achievable is clearly dependent on the scale of the engagement means. However, it will be shown in one of the preferred forms 5 that a high level of distribution is achievable by means without resort of miniaturisation.)

Similarly, the distortion pattern in workpiece material is distributed on the engaged surface of the workpiece (according to the tension pattern generated) , and can be arranged at localities on the engaged surface of the workpiece, without commensurately large distortions being evident at the workpiece boundaries.

One preferred form by which the said distribution of engagement points is obtained is by a means consisting of a planar pad of adjacent bars which engage the said article(s) by means of a multiplicity of sharp pins (similarly raked and in the longitudinal direction of the bar) protruding a uniform extent from the engaging face of each bar, and in which alternate bars are constrained to move together forming two sets of interleaved bars capable of relative reciprocating movement in a direction parallel to the axes of the bars, and in which this reciprocating motion, working in conjunction with the raked pins (which are oppositely raked for each set of bars) enables, when in contact with the said article(s) , engagement and release of the said article(s) as desired.

Hence, for each bar, when moved in the direction of the pin rake the pins are driven into the said article(s), and conversely when moved against the direction of pin rake the pins are ramped out of the said article(s). (The reaction force necessary for this action is provided by the similar but oppositely directed activity of the adjacent bars.) As a result.

U jξtS&^'fa distributed engagement of the article, with a zig-zag shaped tension and distortion pattern, is generated. It is the distributed engagement that enables the workpiece to be picked up over its entire surface irrespective of shape; and it is the relative distortion movements due to the zig-zag tension pattern over the entire surface of the workpiece that creates relative motion, and thus separation, with respect to the workpiece adjacent or underneath the one being picked up.

In this implementation the engagement means (or engagement bars) may be constructed so that the distance between adjacent engagement points on the workpiece is in the order of 5mm for handling narrow sections (or of this dimensional order) however a distance of 10mm to 20mm will provide adequate workpiece control for most garment assembly/handling operations.

Another preferred form by which a distributed engagement pattern is obtained is by means which consist of a planar pad of adjacent bars which engages the said article(s) by means of a multiplicity of sharp pins (preferably similarly raked in- a direction transverse to the length of the bar) and protruding a uniform extent from the engaging face of each bar, and in which each bar is moveable essentially in a lateral direction with respect to each other (in the plane of the pad) , so that in conjunction with the said pins (which are raked towards the direction of movement) , engagement of the said article(s) when in contact is achieved and a unidirectional tension pattern is created over the parts (or the entire surface) of the said article(s) that is engaged, and where movement of the bars in the direction of pin rake engages the said article(s) and conversely movement in the reverse direction' allows disengagement, and where the reaction against the force created in the said article(s) by the said engagement is provided by another pad of (or single) similar engagements bars working in the opposite direction.

In both these forms, the workpiece or article engagement means may be flexible to allow the contours of the workpiece or article to be followed, and separately or additionally, the engagement means may be configured to form an engagement surface that is not necessarily flat and/or whose surface can be controlled to take on any desired shape. Further the pins on the engagement bars may be retractable and/or the extent of protrusion may be adjustable to allow pin engagement to be set to a desired depth. Additionally, in order to reliably disengage workpieces made from material that is very plastic such as soft knitted materials, means are provided which allow the ramp in (when the pins engage) movement distance of the egagement bars to be

* shorter than the ramp out (when the pins disengage) movement distance to ensure that the pins become fully disengaged from the workpiece.

It can be seen in both these forms of the invention, effective workpiece engagement is possible whether the workpiece engagement bars lie within the workpiece boundaries, overlaps the boundaries in parts, or entirely overlaps the workpiece(s) . Therefore, a range of different sizes, and shapes of workpieces can be engaged without the need to make adjustments to the engagement means. This ability to overlap a workpiece enables this form of the invention to effectively control the edges, corners, and projections on a workpiece during handling. Different from the first forms of the invention in which the engagement points are distributed over a large area of the workpiece, is a second form of the invention which comprises means by which the said tension pattern is generated in the workpiece (s) to be engaged by means comprising two or more opposing pairs of engagement bars each of which contains a multiplicity of sharp pins (similarly raked in the direction transverse to the bar's length) protruding a uniform extent from the engaging face of each bar, and in which each said engagement bars of each said opposing pair are moved into contact with the said workpiece (s) and are moved outwards (in the direction i G

of their respective pin rake) relative to each other, thereby generating the said tension in the said workpiece(s) .

A third form of the invention comprises means by which the said tension pattern is generated in the workpiece(s) to be engaged by means comprising two or more opposing pairs of engagement rollers (or part thereof) each of which contains a multiplicity of sharp pin (similarly raked) protruding a uniform extent from the surface of the said roller, and in which the roller pairs rotate in opposite directions while in contact with the workpiece(s) to be engaged, so that the sets of oppositely raked pins on each roller will engage the said workpiece(s) thereby creating a tension pattern in the said workpiece(s) . Disengagement is by reversing the rotation of the rollers.

A variation of the third form of the invention comprises means to utilise the said engagement rollers to engage the workpiece in a semi-distributed manner (that is, workpiece engagement is distributed across the workpiece in lines at a number of intervals along the workpiece length) , wherein the tension pattern is generated by opposing sets of the said rollers, in which each set may comprise of a multiplicity of the said rollers which are rotated differentially in the same direction so that a tension pattern is generated in the said workpiece(s) in between such rollers. For both forms which comprises engagement rollers, to minimise any enlargement of holes created in fine fabric materials due to relative motion of the engagement pins with respect to the fabric material, means are provided to mount the rollers on moveable axles so that when the said roller (s) is rotated into engagement with the said workpiece(s) minimum slippage occurs between the said roller (s) and the surface of the said fabric material. In all the forms of the invention, the magnitude of the movement of the workpiece(s) engagement means

(the engagement bars or the engagement rollers) can be controlled through movement magnitude control or ^• be

^• • limited by a set tension threshold. Additionally, the magnitude of the transient movement may be greater than the steady state position finally achieved, and means may be provided to allow a high rate of movement, as further means to enhance the separation of the workpiece (s) being engaged from the adjacent workpiece(s) .

BRIEF DESCRIPTION OF THE DRAWINGS Some preferred embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view of one preferred form of the invention. Figure 2 is a perspective view of a double action actuator mechanism which may be used as an alternative actuation arrangement in the form of the invention depicted in Figure 1. Figure 3 is a perspective view of another preferred form of the invention.

Figure 4 is a perspective view of a preferred form of flexible workpiece engagement means.

Figure 5 is a perspective view of another preferred form of the invention.

Figure 6 is a perspective view of a preferred form of a roll-into-engagement means being a^' variation for the form depicted in Figure

⁵- . Figure 7 is a partial section view of a preferred means of implementing retractable and adjustable protrusion pins.

DESCRIPTION OF PREFERRED EMBODIMENTS

As a result of problems encountered with the use of local engagement point pick-up apparatus for the handling of soft foam rubber sheets and limp knitted fabric workpieces, improved solutions were sought. In the former application which involved the placement of the foam sheet onto an adhesive layer, problems were encountered with both the amount of sag between engagement points and unacceptable shape distortion of the foam sheet. In the latter application, the ,

workpieces to be transferred were star shaped and once again use of local engagement point pick-up apparatus resulted in loss of control due to excessive drooping in the points of the limp star shaped workpiece. In both applications, consistent separation of the workpiece being engaged from its neighbour in a stack was not assured.

Experiments were conducted to test the concept of distributing the workpiece engagement points over the entire surface of the workpiece, firstly with the view of minimising shape distortion by use of a uniform tension pattern, and secondly to secure the edges and protuberances of a workpiece normally not easily

^• accessible by a- local engagement point pick-up . apparatus, and thirdly to separate the workpiece being engaged from its_. immediate neighbour in a stack by the use of relative motion in the shear direction.

As a result of this experimentation and consequent development, the concepts involved have been embodied into a number of preferred but not exclusive forms which are described in the following.

One preferred form, embodying the distributed engagement points and uniform tension pattern principles, is shown in Figure 1. This form comprises a control module (1) which in turn comprises two guiding means (2,3) a crossar (3,7) actuation means (which can be any known means, but for the purposes of

illustration has been chosen here to be^' spring return pneumatic actuators (4,5) . Mounting means (6,7) allow the control module (1) to be attached to an apparatus with manipulative and/or motion ability (not shown) . Inner crossarms (8,9) and outer crossarms (10,11) (or similar engagement bars (15,16) linking means) , which are free to move but constrained by the guiding means (2,3) , provide attachment points for the engagement bars types (15,16). Engagement bars type (15) are attached to the inner crossarm (8) and outer crossarm (11), and contain pins (for example, (14)), raked in a similar direction. Engagement bars type (16) are attached to inner crossarm (9) and outer crossarm (10) , and contain pins raked similarly but in the opposite direction . to those on engagement bars type (15) .

Further, the inner crossarms (8,9) are connected to their respective actuating means (4,5). In this particular embodiment, the inner crossarms are screwed

(for example, (12) ) , to the actuator pistons (for example, (13)), so that when, say, the actuator (4) is activated, the engagement bars type (15) driven by the crossarm (8) and guided by the crossarm (11) move towards the left of the Figure 1.

By a similar reasoning, the engagement bars type (16) move towards the right of the Figure 1. If the apparatus in Figure 1 is placed on a workpiece (pins in contact) and the actuators (4,5) are driven, the alternate engagement bars type (15,16) move in the opposite directions driving their pins (for example, (14)), into the workpiece engaging over a matrix of points and generating a repeating zig-zag shaped tension pattern and distortion. Such a pattern which is repeated many times over the length and breadth of a workpiece, is in this citation termed a uniform pattern.

Another preferred form, embodying the distributed engagement points and uniform tension pattern principles is shown in Figure 3. Once again, a central module (17) comprises guiding means (18,19) , mounting means., (20) (to a manipulating/handling apparatus, not shown), and actuating means.which in this particular- illustrative embodiment is an electric stepper motor (21) , driving a cam bar (22) , containing a multiplicity of fixed cam bosses, for example, (23). Guided by means (18,19) are engagement bars, for example, (24,25) comprising transversely raked pins, for example, (26) , that are outwardly raked. Also, the engagement bars (24,25) contain cam slots, for example, (27). Rotating actuation of the cam bar (22) , will in conjunction with the cam boss (23) and the cam slot (27) move the engagement bars (25) , in a lateral direction with respect to each other. If the apparatus in Figure 3 is placed on a workpiece, counter-clockwise rotation of the cam bar ^' (22) will cause workpiece engagement and clockwise rotation will cause workpiece disengagement. In the experiments, it was found that for soft knitted materials exhibiting a plastic behaviour, to enhance disengagement a greater movement in the disengage compared with the engage directions was advantageous. An effective means, amongst other known means, to implement this in the appparatus in Figure 3 is the use of a stepper motor (21) to obtain the appropriate motions in and out of workpiece contact to achieve this differential engagement/disengagement movement distances. More specifically, a portion of the engagement stroke is performed off the workpiece and the rest performed on the workpiece, then the disengagement stroke will be longer than the effective engagement one.^' 'Figure 2 shows how this said action is implemented in one form, in the invention shown .in Figure 1; additional actuators (28,29) are fixed to the inner crossarms (8,9) so that they are face-to-face to the actuators (4,5) respectively with the pistons on each pair of actuators connected. Clearly, appropriate actuation of both or one actuator in each pair will give the differential engagement/disengagement movement distances necessary to ensure disengagement in some materials.

In the case of engagement of large workpieces (in which some of its dimension are large compared to the dimensions of convenient engagement apparatus) , then a multiplicity of actuation units can be mounted on a large pad of engagement means. As an illustration of this method. Figure 4 shows two of the actuator units of Figure 1 connected to a long pad of engagement bars. The control module (1) of the two actuator units are mounted by studs (6,7) to some support means which could either maintain the relative positions of the actuator units, or vary them under control, thus changing the form of the engagement surface (formed by the engagement bars types (15,16)), and consequently, that of the workpiece engaged. In the former case, the fixed relative positions of the actuator units is achievable .by, say, a mounting frame, and secondly, to achieve controllable and variable relative positions and attitudes between the actuator • units, the known technology of robots, for example, can be used to manipulate each actuator unit relative to the other (s) . In both of these cases, some degree of flexibility of the engagement means (in this illustration, the engagement bars (15,16)), is provided. In the former case, limited flexibility can be provided by resilient engagement bars (15,16) by using known means such as construction from elastic materials, and this flexibility allows the engagement surface to better follow variations in the contour of the workpiece(s) to be engaged.

In the latter case, the relatively large degree of flexibility required of the engagement bars (15,16) for a useful control of workpiece form (say, to control an originally flat form to that of a moderate curve) , can be provided by engagement bars (15,16) constructed from, for example, materials (or fabrications) exhibiting a high degree of plasticity (for example, by using plastic and wire composites). Further, if continuous engagement across the workpiece is unnecessary then a number of discrete engagement apparatus ^• such as that depicted in Figures 1 and 3 can be moved in appropriate (fixed or variable) formation by robotic or transfer devices for workpiece(s) form control (that is, fixed flat form, fixed non-flat form, or variable surface form) .

In some workpiece (say, stiff materials^') handling^' applications, it was found that engagement over a large part of its surface was unnecessary but that engagement, say, near the opposite boundaries, creating a tension across the workpiece was adequate. For these forms, and other forms that engage the workpiece over several, rather than numerous localities, the following embodiments apply.

One preferred embodiment is that form depicted in Figure 3, but with all of the engagement bars (24,25) removed except the outermost ones at either side; the principle of operation is as described earlier for this embodiment. A further variant of this provides for some immediate engagement bars (24,25) enabling immediate engagement points across the workpiece'. Another preferred embodiment is depicted in perspective in Figure 5, comprising sets of rollers (30,31) with raked pins (32) fixed onto their cylindrical surface. These rollers (30,31) are constrained (by known means such as an axle and bearings) , to rotate relative to a support means, say a frame (33), which is attachable by means, say studs (34) to a manipulation/transfer apparatus (not shown) . The rollers (30,31) are connected to actuation means, say electric stepper motors (35) , which provides controlled rotation of the rollers. With the rollers (30,31) in the position depicted in Figure 3, the rollers are brought into contact with the workpiece (s) (36) (direction of arrows) , the rollers are then rotated; rollers (30)^' clockwise, rollers (31) counter-clockwise, so engaging the pins (32) and tensioning the workpiece (s) (36) , enabling its pick-up. Clearly, the number of rollers (30,31) (or part thereof) , can be varied from one to many on each side, as appropriate to the workpiece to be handled.

In the experimentation with the foregoing embodiment, it was found that for some workpiece materials, undesirable elongated pin holes were created. To overcome this, an alternative roller engagement means was derived in which the engagement pins are rolled into the workpiece with minimum slippage between the workpiece material and the roller surface. A preferred embodiment of such a means is shown in part in Figure 6. The relevant parts are shown comprising the functional means of a rack (37) and pinion (38) , in this embodiment, the pinion is fixed to the roller (39) from which the raked pins (40) protrude. Through pivot means, say a boss and bearing (41) , the pinion (38) is driven by an actuation means (not shown) through force transmitting means and guides (42,43). ^• With the roller (39) in contact with the workpiece (44) , when the pinion (38) is driven to the left, the roller (39) rolls counter-clockwise on the workpiece (44) so engaging the pins (40) -. Within an opposing framework (such, as in Figure 5) of such rollers, a tension is set u in the workpiece (44), enabling its .engagement.

In the experiments with the embodiments so far described, it was found that the magnitude of pin movement whilst in the material of the workpiece (this corresponding to the magnitude of tension generated) can be controlled by either magnitude-of-movement control (whether translational or rotation) or threshold-of-tension control. In the actuation means employing pneumatics for example (say, the apparatus in Figure 1 or if pneumatic actuation means is used to drive the push rod (42) in the apparatus of Figure 6) , threshold-of-tension control is easily provided by regulation of pneumatic pressure. Alternatively, by £ f

controlling the stroke of the pneumatic actuator, magnitude-of-movement control is attained. Further, magnitude-of-movement control can be provided by movement controlled actuators, such as the electric stepper motor drive embodied in the apparatus of Figure 3, in this case simply by specifying the number of steps to be turned by the stepper motor, the desired magnitude-of-movement is obtained. Furthermore, separation is further enhanced by means providing rate-of-tensioning control and transient movement in excess of the at-rest movement (when engaged) . For certain materials, these said additional functions are advantageous. Implementation is simply by the known methods of actuator control, for example, in the electric stepper motor actuation embodiments by controlling the rate, number and directions of step triggering signals.

In a further aspect of the experimentation, it was discovered that certain materials do not disengage as easily as others, to overcome this aspect, a pin retraction means was devised. (This applies to the embodiments not employing the engagement roller principle.) One preferred embodiment of this pin retraction means is shown in Figure 7. This embodiment has been devised to operate with the apparatus depicted in Figure 1, it is a scrap section illustrating a relevant portion of the pin retraction means. Extended pins (45,46) on engagement bars types (15,16) are attached on modified crossarms as on example 47. Similarly, to the embodiment in Figure 1, the crossarms move within guiding means (2,3) . However, the modified crossarms (47) embody a cam surface which engages a ramp means (48) which is fixed to a framework which connects to a perforated plate (49) situated over the engagement surface of the apparatus, with perforations lining up with the matrix of pins (45,46). (Pins (45) belong to type (15) engagement bars and pins (46) to the adjacent type (16) engagement bars.) This perforated plate is biased outwards (see arrows) by forcing means such as the compression spring (50) and guide (51) . 'When-the crossarm. (47) is moved by the actuator means (4,5), interaction of the cam surface' and ramp means (48) retracts the perforated plate (49) at the same time that the pins (45,46) are driven into the workpiece (52) (as the apparatus is maintained in contact with the workpiece (52) ) ; when the crossarm (47) is actuated in the reverse direction, the pins (45,46) are retracted out of the workpiece (52) and the perforated plate (49) spring outwards serving to eject the workpiece (52) . The dimensions of the ramp means (48) are important for regulating the amount of protrusion of the pins; its effective thickness, t, controls the said protrusion and may be alternatively embodied to allow effective thickness adjustment. While this embodiment is applicable to the form of „the apparatus shown in Figure 1 and Figure 2, the principles involved are equally applicable to other forms such as that depicted in Figure 3.

In the case of non-retractable pins, engagement bars and engagement rollers are selected with appropriate pins protrusion extent to match the thickness of the article(s) intended for engagement.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. An apparatus for engaging and/or picking up an elastic, porous, limp, mesh, cellular, woven or knitted workpiece, comprising at least two engagement members each of which carries a plurality of workpiece engaging projections, movement means to move at least a surface of at least one of the engagement members relative to the other member, and means to move the device into and out of contact with a face of a workpiece, the workpiece-engaging projections being such that when the engagement members are brought into contact with the said face of a workpiece and the movement means caused to move the at least one surface of the at least one of the engagement members relative to the other the workpiece is engaged by the workpiece-engaging projections on at least the said two engagement members and the workpiece tensioned therebetween such that the- workpiece is retained on the projection by the said tension.

2. The apparatus of Claim 1, wherein the said tension pattern, and consequently the holding force pattern and distortion pattern, are generated over substantially one entire face of the said article by means of which a multiplicity of engagement points are distributed or substantially distributed, over the said face.

3. The apparatus of Claims 1 and 2, wherein the distributed face engagement and distortion means consist of a planar pad of adjacent bars which engage the said article (s) by means of a multiplicity of sharp pins (similarly raked substantially in the longitudinal direction of the bar) protruding a uniform extent from ^•- the engaging surface of each bar, and in which alternate bars are constrained to move together forming two sets of interleaved bars capable of relative reciprocating movement in a direction parallel to the axes of the bars, and in which this reciprocating motion, working in conjunction to the raked pins (which are oppositely raked for each set of bars) enables when in contact with a face of the said article(s), engagement and release of the said article as desired. . For each bar, when .moved in- the direction substantially of the pin rake the pins are driven into the said article, and conversely when moved against the direction of pin rake the pins are ramped out of the said article(s). (The reaction force necessary for this action is provided by the similar but oppositely directed activity of the adjacent bars.)

As a result the distributed tension described in Claim 2 is implemented as a zig-zag pattern over substantially the engaged face, of the said article.

4. The apparatus of Claims 1 and 2 wherein the said surface engagement means consist of a planar pad of adjacent bars which engages the said article(s) by means of a multiplicity of sharp pins (similarly raked in a direction substantially transverse to the length of the bar) and protruding a uniform extent from the engaging face of each bar, and in which each bar is moveable essentially in a lateral direction relative to each other (in the plane of the pad) , so that in conjunction with the said pins (which are raked towards the direction of movement) , engagement of the said article(s) when in contact is achieved and -a unidirectional tension pattern is created over the parts (or one entire face) of the said article(s) that is engaged, and where movement of the bars in the direction (substantially) of pin rake engages the said article(s) and conversely movement in the reverse

"direction .allows disengagement, and where the reaction against the force created in the said article(s) by the said engagement is provided by another pad of (or single) similar said engagement bars working in the opposite direction.

5. The apparatus of Claims 1, 2, 3, and 4 wherein the article(s) engagement means are flexible to allow the apparatus to follow the contours of the surface of the article(s) to be engaged.

6. The apparatus of Claims 1, 2, 3, and 4 wherein the article(s) engagement means form an engagement surface which is not necessarily flat, and/or whose surface can be controlled to take on a desired form.

7. The apparatus of Claims 1, 2, 3, 4, 5, and 6 1 1

wherein the engagement means are retractable and/or may be set to engage to a desired depth.

8. The apparatus of Claims 3, 5, 6, and 7, or Claims 4, 5, 6, and 7, wherein the said engagement bars are moved under movement magnitude control or tension threshold control, and optionally rate of movement control.

9. The apparatus of Claims 3, 5, 6, 7, and 8, or Claims 4, ^'5, 6, 7, and 8, wherein the movements of the said engagement bars can be controlled such that a portion of the engagement movement can be performed out of contact with the article(s), thus allowing the remaining engagement movement (which is in contact with the article(s)) to be of a. lesser distance than the disengagement movement to enhance the reliability of workpiece(s) release. Additionally, wherein the rate of disengagement can be controlled also to enhance article(s) release.

10. The apparatus of Claim 1 wherein the said tension pattern is generated in the article(s) to be engaged by means comprising two or more opposing pairs of engagement bars each of which contains a multiplicity of sharp pins (preferably similarly raked in the direction transverse to the bar's length) protruding a uniform extent from the engaging face of each bar, and in which each said engagement bars of each said opposing pair are moved to engage the said article(s)

&rl^'.. and are moved outwards relative to each other, thereby generating the said tension in the said article(s), under movement magnitude or tension threshold control and/or rate of movement control.

11. The apparatus of Claim 1 wherein the said tension pattern is generated in the article(s) to be engaged by means comprising two or more opposing pairs of engagement rollers (or part thereof) each of which contains ^'a multiplicity of sharp pins (similarly raked substantially in the radial direction) protruding a uniform extent from the surface of the said roller, and in which the rollers rotate in opposite directions while in contact with _the article(s) to be engaged, so that the sets of oppositely raked pins on each roller will engage the said article(s) thereby creating a tension pattern in the said article(s). Disengagement is by reversing the rotation of the rollers.

12. The apparatus of Claim 1 and 11 wherein one or both of each pair of said opposing rollers is/are mounted on a moveable axle(s) so that when the said roller (s) is rotated into engagement with the said article(s), minimum slippage occurs between the said roller (s) and the surface of the said article(s) .

13. The apparatus of Claims 11 or 12 wherein the said roller rotation is under movement magnitude or tension threshold control, and optionally with rate of movement control.

14. The apparatus of Claim 11 or Claim 12 wherein the said tension is generated in the said article (s) by opposing sets of the said rollers, in which each set may comprise of a multiplicity of the said rollers which are rotated differentially (under movement magnitude or tension threshold control) in the same direction so that a tension pattern is generated in the said article (s) in between such rollers.

15. The apparatus of Claims 3, 5, 6, 7, 8, and 9 or Claims 4, 5, 6, 7, 8, and 9 modified wherein a number of the said apparatus actuate a common set of engagement bars for the handling of relatively large or long article(s). Alternatively, wherein a number of the said apparatus (unmodified) are positioned (fixed or variably) in formation once again for the handling of relatively large or long article (s) .

16. An apparatus for the engagement or picking up of elastic, porous, limp, mesh, cellular, woven or knitted articles substantially as described with reference to the accompanying drawings and descriptions thereof.