HANDLING WORKPIECES OF FLEXIBLE SHEET MATERIAL

Abstract: Apparatus (1) for handling workpieces of flexible sheet material comprises a substantially flat first support surface (6) and suction chamber means (8) defined in part by a substantially flat second support surface. The suction chamber means (8) are connected to the first support surface (8) by hinge means (5) which enable the second support surface to lie in the same plane as the first support surface or to be pivoted through approximately 180 degrees to lie on top of the first support surface (6). By controlling the creation and release of suction and the pivotal movement of the second support surface, the apparatus (1) is capable of performing at least three of laying up, turning over, folding and unfolding operations on a workpiece.

Description: Handling workpieces of flexible sheet material TECHNICAL FIELD This invention relates to apparatus for handling workpieces of flexible sheet material, e.g. plies of δ fabric. BACKGROUND ART It is often desirable when handling workpieces of fabric to be able to perform a variety of different opera¬ tions on those workpieces. In particular it is desirable 10 to perform the following operations: 1. Lay-up This involves precisely laying one workpiece on top of another workpiece in the desired orientation, lδ 2. Turn over This involves turning a workpiece over - i.e. so that its originally downwardly facing surface is turned so as to face upwardly. 3. Folding 20 This involves folding a workpiece on itself. 4. Unfolding This involves unfolding a previously folded workpiece or two previously layed-up workpieces which have been joined, e.g. stitched, together. 2δ In each of the operations referred to above, the workpieces should remain completely flat and not crinkled or "rucked" . In the prior art, it is known for a single piece of apparatus to perform one or two of the above-identified operations. For example, in WO 86/03949 there is described a laying-up apparatus. DISCLOSURE OF THE INVENTION The present invention seeks to provide apparatus for 5 handling workpieces of flexible sheet material capable of performing at least three of the above-identified workpiece handling operations. The invention also seeks to provide a universal apparatus capable of handling workpieces of different shapes and sizes. 10 According to one aspect of the present invention apparatus for handling workpieces of flexible sheet mat¬ erial comprises a substantially flat first support surface, suction chamber means defined in part by an a ertured support providing a substantially flat second support lδ surface, hingeing means for enabling pivoting of the suction chamber means between a first position in which the first and second support surfaces are arranged side by side to provide a substantially continuous flat supporting surface and a second position in which the second support 20 surface is positioned closely above the first support surface, actuating means for pivoting the suction chamber means between its first and second positions, suction means for generating sub-atmospheric pressure in said chamber means, and selecting means for selecting through which 2.5. ' apertures of the apertured support suction will be applied when the suction means generates sub-atmospheric pressure in said chamber means. The application of suction through apertures of the apertured support enables a workpiece to be positively 30 held in position on the second support surface. By select¬ ing through which apertures of the support suction is applied, only those areas of the second support surface supporting a workpiece (and normally also these areas immediately surrounding the supporting means ) will have suction applied thereto. Accordingly the suction force can be concentrated to the desired area of the second support surface and the generation of unnecessary suction energy is minimised. Thus the effective working area of the second support surface is "customised" to the size and shape of the workpiece to be handled. Conveniently the suction chamber means is divided into a plurality of suction chambers, e.g. nine, which are typically, but not essentially, equally sized, and the selecting means enables suction from said suction means to be selectively applied, or not applied, to each one of said chambers. There will of course be a greater degree of control of the size of the working area of the second support surface the more suction chambers that are pro- vided. However this increased control is off-set by the cost and complexity of providing a large number of suction chambers. For a second support surface having a dimension of 900mm x 900mm, nine suction chambers, each 300mm x 300mm square and 60mm deep, have proved to provide a good com- promise between control and cost/complexity. Another method of controlling the size of the second support surface is to mask off the apertured support in dependence on the size and shape of workpiece to be hand¬ led. In this case the suction chamber means would be a δ large single chamber and masks would be arranged on top of or beneath the support to block apertures not required. However this method of controlling the size of the working area of the second support surface does not lend itself well to automatic control and is not preferred. 0 The apertured support preferably comprises a per¬ forated or foraminated sheet, e.g. of stainless steel, with the perforations typically circular and having a diameter of 1mm and located on 2mm isosceles triangular pitch. A grid supporting frame is conveniently provided beneath the 5 perforated sheet. Preferably the first support surface is also aper¬ tured, e.g. a perforated or foraminated sheet similar to the said apertured support. In this case the perforated sheet is also supported from below by a grid supporting δ frame and is open to atmosphere from below over at least the majority of its area. In order to perform a folding operation on apparatus according to the invention, it is necessary: (a) to position a workpiece so that it covers both 10 the first and second support surfaces when the suction chamber means is in its first position; (b) to positively hold the portion of the workpiece supported on the second support surface by the application of suction; lδ (c) to pivot the suction chamber means into its second position; (d) to release the suction so as to release the positive hold on the previously held portion of the workpiece; and 20 (e) to move the suction chamber means back to its first position. If the fold line coincides with the hingeing or pivoting axis of the suction chamber means, the workpiece crumples or wrinkles in the region of the fold. According- 2δ ly it has been found to be advantageous to form the fold along part of the workpiece supported on the first support. This is achieved, in practice, by positively holding a strip of the workpiece along a narrow region of the first support surface spaced a short distance, e.g. 15mm, from 30 the hingeing axis. Preferably, therefore, a suction chamber is arranged to apply suction beneath a narrow portion of the apertured first support surface spaced a short distance from the hingeing axis. Preferably the portion of the apertured first support surface adjacent said narrow portion but remote from the hingeing axis is open to atmosphere beneath the support surface. Preferably the actuating means provides controlled movement of the suction chamber means between its first and second positions. In particular the suction chamber means is controlled so as to smoothly accelerate away from, and to smoothly decelerate into, each of said first and second position. According to another aspect of the present invention an apparatus for handling workpieces of flexible' material enabling at least three of laying-up, turning over, folding and unfolding operations to be performed by controlling the application and removal of suction to an apertured pivot- able support and controlling the pivoting movement of the pivotable support relative to a fixed support. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a partly cut away perspective view of apparatus according to the invention for handling work- pieces of flexible sheet material, Figure 2 is a schematic side view, on an enlarged scale, of a portion of the apparatus shown in Figure 1, Figures 3a and 3b schematically illustrate a "lay-up" operation, Figures 4a and 4b_ schematically illustrate a "turn over" operation, Figures 5a and 5b_ schematically illustrate a "folding" operation, Figures 6a . and 6b_ schematically illustrate an "unfold- ing" operation, and Figure 7 illustrates an arrangement for automatically inserting and removing a non-porous member during an unfolding operation. BEST MODE OF CARRYING OUT THE INVENTION Figure 1 shows an apparatus, generally designated by the reference numeral 1, for handling workpieces of flex¬ ible sheet material, e.g. plies of fabric. The apparatus 1 is intended to be incorporated into an automated garment manufacturing process. The apparatus 1 comprises a main frame 2 carrying a fixed table 3 and a pivotable table 4 mounted on the frame by a hinge and drive mechanism δ at each side of the apparatus 1. The table 3 comprises an apertured sheet 6, e.g. a perforated polished stainless steel sheet, posi- tioned on top of a supporting grid 7. The table 4 com¬ prises a vacuum box 8 positioned beneath, and closed on its upper side by, a further apertured sheet 9 supported on a supporting grid 10. In the position of the table 4 shown in Figure 1 , the apertured sheets 6 and 9 provide a sub- stantially flat uninterrupted work surface. Each apertured sheet typically has an area of 900mm and has 1mm diameter perforations located on 2mm isosceles triangle pitch. The hinge and drive mechanisms 5 are normally posi¬ tioned beneath the level of the flat work surface to provide a large flat surface over which workpieces can be easily moved but, prior to pivoting movement of the table 4, are raised into operative positions by jacks 11 and located in position by pneumatic ram actuated hinge locks 13. When the hinge and drive mechanisms 5 are in their operative positions, the table 4 can be pivoted through approximately 180° between an "open" or first position (shown in Figure 1) and a "closed" or second position in which the apertured sheet 9 is positioned over the aper¬ tured sheet 6. This pivotal movement of the table 4 is effected by pneumatically operated rams 12. To ensure a rapid cycle of movement of the table 4 through 180° in less than 3 sees, but with controlled deceleration, an electro pneumatic circuit is employed. By fitting two micro - switches (not shown), that can be selected according to the . direction of table movement and can be switched relative to table angular position, the switched signal can be used to operate a solenoid operated pneumatic valve (not shown) whose function is to divert exhaust air from the driving cylinders 12 through a variable restrictor (not shown), thus allowing an adjus- table exhaust discharge from the driving cylinders 12. Before the angular movement of the table is completed, the solenoid valve is de-energised, switching it back to its former state, thus allowing full flow of air, to the now charging side of the driving cylinders. This system ensures maximum acceleration in both movement direction, with controllable deceleration in both directions. The vacuum box 8 is sub-divided into a plurality, e.g. nine, of chambers 14 isolated from each other. An air suction motor or pump (not shown) is connected to a connec- tion duct lδ which is connected by ducts 16 to each chamber 1 . An electrically operated damper valve 17 is arranged to control the flow of air through the duct 15 and each of the ducts 16 can be opened or closed to control the ap¬ plication or removal of sub-atmospheric pressure to the chambers 14. Although not shown in Figure 1 , a further vacuum chamber 20 (see Figure 2) is arranged beneath the edge of the apertured sheet 6 for applying sub-atmospheric pressure through a narrow portion of the sheet 6 extending across the width of the sheet 6 parallel to the pivoting axis P of the table 4. This narrow portion has a width X, typically 50mm, and is displaced a distance Y, typically Iδmm, from the pivoting axis P. Apart from this narrow portion defined by the vacuum chamber 20, the remainder of the underside of the apertured sheet 6 is freely vented to atmosphere. The apparatus 1 functions as follows. At the start of a manipulator sequence, the table 4 is flat in its first position, the hinge and drive mechanisms δ are retracted, the hinge locks 13 are disengaged and the table drive cylinders 12 are exhausted of pressurised air. Those chambers 14 over which suction is required to be applied are selected, e.g. manually, to suit the "suction area" to the size and shape of workpiece to be handled. The first action of a manipulator sequence is to move the hinge and drive mechanisms δ into their table pivot positions by energising the jacks 11. When both the left and right side mechanisms 5 are in position, as indicated by two detectors (not shown) the hinge locks 13 are ener- gised thereby locking the mechanisms δ into position. When it has been confirmed by two limit switches that the locks 13 have engaged properly, the drive cylinders 12 are charged up with air for a set time. Following this, suction is applied as required to the chamber 20 and/or 0 selected chambers 14 selected as required by opening Butterfly valves using solenoid valves. After a short time delay, to allow the suction to reach its working rate, the drive cylinder solenoid valve is energised and the table 4 begins to pivot from its first position towards its second δ position. When the table 4 has moved through approximately 135° its presence is detected by a limit switch (not shown). At this point, the air exhausting from the drive cylinders 12 are switched through a solenoid valve to restrict the air flow. This has the effect of slowing the table 4 down as it reaches the 180° position, or the completely folded second position. When the table is in its second position, as indicated by a limit switch (not shown) the hinge suction (to chamber 20) and main table air suction (to chamber 14) can be altered as selected if required. A short time delay follows to allow both the suction to change if appropriate and for the table 4 to settle after its pivoting operation. Pivoting of the table 4 in the reverse direction can then take place. To pivot table 4 back to its first position, the drive cylinder solenoid valve is de-energised. A special valve is simultaneously energised. This has the combined effect of pivoting the table 4 away from the surface 6 very slowly, thus preventing a rush of air which could disturb the workpiece being handled. The special valve is de- energised when a detector senses the table 4 is at ap¬ proximately 150° , allowing the table 4 to pivot at normal speed under control of the drive cylinders 12, until the 45° position is reached. At this position a limit switch detects the table 4 and switches the drive cylinder ex¬ hausting air through a solenoid valve to restrict the air flow. As for the last part of the pivoting operation, this has the effect of slowing the table down as it comes to rest in the zero degree first position. When the table has returned to the zero degree posi¬ tion as indicated by a detector (not shown), the drive cylinders 12 are discharged of air for a set time by energising an air dump valve. The hinge locks 13 are then retracted by de-energising their solenoid valve. When detectors detect that the locks 13 have retracted, the hinge mechanisms δ are retracted. When retracted the cycle can be repeated if required. The various stages for performing lay-up, turn over, folding and folding operations are shown in schematic form in Figures 3aι, 3b_; 4a, 4b; 5a, 5b and 6a, 6b, respec¬ tively. These Figures are, on the whole, self-explana¬ tory, with the Figures designated "a" showing the "start" position of the tables 3 and 4 with at least one workpiece Fl ( or Fl and F2 ) located thereon and the Figures designated "b" showing the tables 4 after they have reached their second positions and are just commencing their return pivoting motion. In the Figures, "S" designates suction applied through the apertures of the apertured sheet 9 of the table 4, "SI" designates suction applied through the apertures of the apertured sheet 6 above the narrow chamber 20, "H" designates the "hinge" of a folded workpiece and "P" designates the pivot point of the table 4. Thus in order to perform a lay-up operation, suction S is applied initially to workpiece F2 which clamps the latter to the sheet 9 (Figure 3a). The table 4 is then pivoted to its second position, suction S is released and the table 4 pivoted back to its first position (Figure 3b_ shows the table 4 at an early stage of its return pivotal movemen ) . In order to perform a turn over operation ( see Figures 4a . and 4b_) , the same sequence as for the lay-up operation is performed with the exception that no workpiece is supported on the sheet 6 of table 3. In order to perform a folding operation, the workpiece F is positioned over the pivot axis P and suctions S and SI are applied (see Figure 5a). When the table 4 reaches its second position, suctions S and SI are released (see Figure δb) and the table 4 returned to its first position. The suction SI may be kept on during at least the initial stages of the return pivoting movement of the table 4. In order to perform an unfolding operation it is generally necessary to insert an impervious separator I between the layers of the folded workpiece F. Normally a workpiece to be "unfolded" will have been formed in pre¬ vious operations by a lay-up operation on two workpieces followed by a stitching operation on ' the two "layed-up" workpieces. In this case the impervious separator I is normally positioned on top of the workpiece Fl prior to laying F2 on top thereof in the lay-up operation described with reference to Figures 3a and 3b. The impervious separator I can be so inserted with the aid of a robot 30 (see Figure 7) having a gripper 31 with suction cups 32. A stack of impervious separators I are stored at 33. In the unfolding operation, the "folded" workpiece F is positioned on table 3 with the hinge of the workpiece spaced from the pivot axis P (see Figure 6a). The table 4 is pivoted to its second position and suctions S and SI are applied. The top layer of the workpiece F and the impervious separator I are clamped to the table 4 and the table pivoted back to its first position. Since the separator I is impervious, little or no movement of the lower layer of the workpiece F should occur during initial stages of the return table pivoting* (see Figure 6b_) since no air can be sucked through the separator.

Claims: CLAIMS 1. Apparatus (1) for handling workpieces of flexible sheet material comprising a substantially flat first support surface (6), suction chamber means (8) defined in part by an apertured support (9) providing a substantially flat second support surface, hingeing means (5) for ena¬ bling pivoting of the suction chamber means (8) between a first position in which the first and second support surfaces are arranged side by side to provide a substan- tially continuous flat supporting surface and a second position in which the second support surface is positioned closely above the first support surface (6), actuating means (12) for pivoting the suction chamber means between its first and second positions, suction means (15, 16) for generating sub-atmospheric pressure in said chamber means, and selecting means for selecting through which apertures of the apertured support (9) suction will be applied when the suction means (15, 16) generates sub-atmospheric pressure in said chamber means (8). 2. Apparatus according to claim 1, characterised in that the suction chamber means (8) is divided into a plurality of suction chambers (14) each of which is selec¬ tively at least partially evacuable. 3. Apparatus according to claim 1, characterised by masking means for blocking off selected apertures of said apertured support (9). 4. Apparatus according to any one of the preceding claims, characterised in that the apertured support (9) comprises a perforated or foraminated sheet. 5. Apparatus according to any one of the preceding claims, characterised in that the first support surface (G) is apertured. 6. Apparatus according to claim 5, characterised in that suction chamber means (20) are arranged beneath the apertured first support surface (6) for applying suction through apertures of the first support surface (6) located in a suction zone of the first support surface (6). 7. Apparatus according to claim 6, characterised in that the suction zone is spaced from the pivoting axis of the suction chamber means (8). 8. Apparatus according to claim 7, characterised in that the portion of the first support surface (6) adjacent to said suction zone but remote from the pivoting axis is apertured with the apertures open to atmosphere beneath the first support surface. 9. Apparatus according to any one of the preceding claims, characterised in that the actuating means (12) is arranged to provide controlled movement of the suction chamber means (8) between its first and second positions so that the suction chamber means (8) achieves smooth ac¬ celeration away from, and smooth deceleration into, each of its first and second positions. 10. Apparatus according to any one of the preceding claims, characterised by control means operable selectively to create suction, release suction and pivot said suction chamber means (8) to facilitate at least three of laying- up, turning over, folding and unfolding operations.

Inventors: FLAVELL JOHN, NASH MICHAEL ANTHONY, FLAVELL, JOHN, NASH, MICHAEL, ANTHONY
Applicants: COURTAULDS PLC
Application year: 1989
Main classification: B65H45
IPC codes: A41H43, B65H15, B65H45, B65H47, D06F89