WO1987005472A1 - Method and device for setting fabric on a cutting table - Google Patents

Abstract

Method for setting a length of fabric (4) flat on a cutting table (1) having a non-slipping surface providing for the permanent an accurate positioning of the fabric, characterized in that a slipping sheet (3) is placed on the cutting table (1), in that the fabric is accurately positioned on said sheet (3), in that the fabric is fixed by side presser means (51, 52) and radial presser means (50) which are independently controlled, and in that the slipping sheet (3) is removed without displacing the fabric.

Description

Method and device for placing fabric on a cutting table

Industrial manufacturing processes use automated cutting of fabric coupons to make the pieces constituting a suit, a tailor, an overcoat, etc.

This cut is made on flat tables, rectangular in shape and arranged horizontally. The size of the tables makes it possible to spread out a fabric coupon.

The surface of the table must have three qualities: a) be slippery so that it is possible to spread the fabric very uniformly without any folds with a precision of position tight compared to benchmarks related to the table, b) not be slippery so that the fabric cannot move either during a movement of the table or during cutting, c) be permeable to gas to allow the suction of the fumes given off by laser cutting, d) present the minimum surface area free to limit the effects of the laser on the table surface.

An aluminum honeycomb meets criteria b), c), d) very well and criterion a) very poorly. A solution was provided by the request FR 85.09422

Al.

A separator belt is unwound above the conveyor belt at a location upstream from the loading station, the speed of advance of the separator belt being lower (or at most equal) than that of the conveyor belt. We stop the two belts in the loading area, place the fabric and pinch the end of the fabric on the conveyor belt, then remove the separator belt.

This solution poses friction problems of the separator belt on the honeycomb conveyor belt because of the mode of movement of the separator belt which is pushed by the notched cylinder by rubbing on the honeycomb conveyor belt, with the recognized risk of fold formation.

In addition, once the fabric is in place, only the end of the coupon is pinched along the line of notches, therefore along a line perpendicular to the movements of the carpets.

Removal of the separating mat creates tension on the fabric in the direction of movement which can cause narrowing in the transverse direction. However, the fabric purposely slips badly on the honeycomb surface.

We will thus manage to form folds and undulations along the fabric.

The present invention provides solutions to these problems - friction,

- creases on the fabric.

A first characteristic of the invention is to move the sliding sheet (playing a role analogous to the separator mat of the aforementioned request) by pulling it which allows it to be stretched.

A variant even avoids any contact between the slippery sheet and the honeycomb which eliminates wear by friction.

Another characteristic of the process is to pinch the fabric not only on a line perpendicular to the movements of the carpet but also on the two edges of the carpet where the suppression of folds and undulations of the fabric.

The present process can be followed in the light of the explanatory description which follows, made with reference to the accompanying drawings.

Figure 1 schematically shows a side view of the cutting table. The X axis will always be along the length of the table, the Y axis along the width and the Z axis is vertical.

It appears in this figure 1 a table (1) with its upper surface (2) not slippery. On this table (1), it is put a sliding sheet (3) and above a fabric coupon (4).

To make the drawing clearer, the surfaces have been artificially separated. Note that the sliding sheet has the same width as the table and a length greater than that of the table. Figure 2 shows a top view of the table (20).

Figure 3 shows the end of the sliding sheet (3), which will coincide with the end A of the table (along X), we note the presence of notches (31).

Figure 4 shows in side view the table (1) ready for cutting, the fabric coupon (4) placed on the upper surface (2) of the table and the sliding sheet (3) removed (along X) from the surface of the table.

Figure 5 shows a top view of the table covered with the sliding sheet and the coupon (4). The notches (31) of the sliding sheet are along the width FG of the cutting table. In line with each of the notches (31), a presser (50) presses the fabric vertically on the upper surface of the table without touching the sliding sheet. The part of each presser in contact with the fabric is included in the notch. On the long sides EF and GH of the cutting table, pressers (51) and (52) (distributed over the entire length) apply the fabric coupon and the sheet sliding on the upper surface of the cutting table.

The total pressing force of the pressers (50) must be sufficient to block the fabric.

On the other hand, the total force of the pressers (51) and (52) must allow the sliding sheet to slide without the fabric moving.

The pressers (50) will be called: radial and the pressers (51) and (52): lateral.

The operating mode is as follows: a) placement on the cutting table of a sliding sheet by pulling it along the X axis until it is flush with the FG side of the table, b) placement of the fabric that the '' you can move easily on the

<_ slippery sheet. One can in particular put selected points of the coupon (intersections of stripes for example) on pre-established marks, c) actuation of the pressers (50) which press the fabric on the table through notches (31) of the sliding sheet , d) actuation of the pressers (51) and (52) which apply the fabric lightly to the sliding sheet, e) pulling the sliding sheet parallel to X from F to E and from G to H without the fabric moving since it is held firmly by the pressers (50), f) total removal of the sliding sheet so that the fabric rests completely on the non-sliding upper surface of the cutting table.

The adjustment of the pressers makes it possible to precisely maintain the position of the fabric relative to the preset marks. This conservation makes it possible to automatically cut the fabric according to a program without fumbling.

The upper surface of the table is sufficiently non-slippery so that all the pressers can be erased and the cutting carried out without any displacement of the fabric.

The erasure of the pressers makes it possible to completely use the surface of the coupon to cut various pieces without being hindered near the sides EF and GH on the one hand, and FG on the other hand by the grip of the pressers. Example of devices for implementing the method:

1) Upper surface of the cutting table It is advantageous to use a honeycomb of light alloys with very thin walls as shown in FIG. 6 in top view. We can advantageously take p = 4 to 10 mm with a wall thickness e 0.30 mm.

A honeycomb sheet of approximately 15 to 20 mm thick is produced with this material.

There is thus a very small fabric-metal contact surface which is very interesting in the case where the cutting instrument is a laser focused on the tissue.

The sharp edge of each cell completely prevents the tissue from sliding over the top surface of the honeycomb. 2) Slippery sheet

It is advantageous to choose a thin sheet material sufficiently rigid to spread flat without any folds and sufficiently flexible to be able to be wound on a drum. One can use a sheet of stainless steel about 1/10 mm thick or a sheet of plastic and in particular polyester of a few tenths of a millimeter thick.

The Applicant has obtained all satisfaction with a sheet of MYLAR (registered trademark Dupont de NEMOURS) 0.35 mm thick. 3) Moving the sheet

Figure 7 shows in perspective the cutting table (1) on which is placed the sliding sheet (3).

Clamps (70, 71) clamp two corners of the sheet (3) and traction is exerted on each clamp by a chain driven by a pinion. We therefore see on one side the chain (72) and the sprocket (74) and on the other side of the chain (73) and the sprocket (75). A single motor shaft (76) drives in synchronism the two identical pinions (74, 75) carrying out an equal displacement at equal speed for the two clamps (70, 71). This allows the sheet (3) to be driven parallel to the X axis without lateral offset along Y.

The sheet (3) is placed on a roller (77) whose shaft (78) is braked (by a counterweight or by a spring for example, creating a restoring torque therefore a restoring pulling force on the sheet).

By leaving equal and opposing set forces in action on the roller and on the chains, the sheet (3) is tensioned to make it flat.

Under the sheet (3), there is the upper surface of the table with the hexagonal cells (79). To remove the sheet, the tensile forces on the clamps are reduced or canceled and the sheet is rolled up on the roller (77).

4) Placement of the fabric For example, manual placement so as to make a certain number of singular points of the fabric coincide (intersection of stripes for example) with a luminous mark projected vertically on the fabric.

5) Radial pressers They can be constituted by pneumatic cylinders acting vertically, positioned regularly on the FG side of the cutting table. They are carried by a transverse beam linked to the sides of the frame of the cutting table.

In Figure 8, which is a vertical section of the cutting table, we see the frame (81) and the table (1). A beam (82) carries the jacks (83) with their rod (84). A tubing (85) supplies the actuating fluid to the jack. We have a similar result with electric cylinders.

9) Lateral pressers (Figure 9) A horizontal shaft (90) linked to the frame (81) is arranged on each side of the table parallel to the direction X. On this shaft (90) are fixed cams (91) distributed regularly over full length.

A rotation of the shaft brings the cams (91) into contact with the fabric (not shown) placed on the table (1).

Reverse rotation brings the cam to position 92 completely freeing the fabric and the table surface.

For example, 10 pressers will be placed on each of the shafts. The pressing force must be sufficient to keep the fabric wrinkle free while allowing the MYLAR sheet to slide between the fabric and the top surface of the table.

7) Cutting table with vertical displacement A variant has been shown in FIGS. 10 to 13 interesting method, following a vertical section passing through the X axis (of Figure 1).

The upper face of the cutting table having a honeycomb structure has a highly abrasive surface since it appears as a succession of sharp edges.

The abrasive effect is particularly strong on the part of the sliding sheet having cutouts as taught in the aforementioned application. This abrasive effect is much more marked in the phase of placing the sliding sheet, on the one hand because of the speed, on the other hand because of the orientation of the cuts.

In fact, for reasons of productivity, it is very beneficial to minimize the time for setting up the sliding sheet, and therefore to operate at high speed. On the other hand, the problem does not arise for the removal of the slippery sheet after the placement of the fabric coupons because a slow speed and a slow acceleration are necessary so that the fabric does not move.

To avoid friction of the moving sliding sheet on the (fixed) cutting table, a cutting table with vertical displacement is used at least for the honeycomb part.

The table can be either in the low position during the positioning of the sliding sheet, or in the high position for the positioning of the fabric and the removal of the sliding sheet. Figure 10 shows the sliding sheet unrolling while the table is in the low position.

Figure 11 shows the sliding sheet completely unrolled so fixed while the table is in the low position.

Figure 12 shows the sliding sheet while the table is in the high position.

Figure 13 is a variant of the device of Figures 10, 11, 12 for controlling the movement of the table.

The actual cutting table consists of a metal frame and a honeycomb parallelepiped structure, (item 81). A frame (82) guides the movements of Table. An articulated chisel (83) resting on a horizontal crosspiece (84) makes it possible to impose a vertical displacement on the table (81).

In Figure 10, the chisel is in the folded position (item 83) while in Figure 12, it is in the unfolded position (item 85). The deformations of the chisel are controlled by known means such as a screw.

For the establishment of the sliding sheet, originally wound on the roller (86), we start by putting the cutting table in the low position (Figure 10), and we unroll the sheet pulling by the rou. water (88) on the clips (87) of the sheet. This is done until the sheet (89) is in place between the two rollers (86) and (88) (Figure 11).

To make the position of the sheet (89) stand out better, its thickness has been deliberately exaggerated very strongly in the figures.

Then we go up, by action on the chisel, the table (81), in the high position, so that the upper face of the table is as close as possible to the sheet (89) in Figure 12, we have shown the sheet (89) and the table (81) in contact, which is obviously the limiting case.

If the tension on the sheet (89) (via the rollers (86) and (87) in particular) is large enough so that the deflection of said sheet is negligible, it is advantageous not to have contact but rather to leave a clearance of less than 3 mm and preferably close to 1 mm between the sheet (89) and the upper surface of the table (81). When operating with a sheet (89) of small thickness, it will not be possible to impose a large tension and in this case, there will be contact between the sheet and the table. FIG. 13 shows a variant for the vertical displacement of the table without showing the sliding sheet and the rollers. On a horizontal crosspiece (90) are placed jacks such as (91) and (92). The rods (93) and (95) bear under the table (81). The pipes (97) and (98), joined to the pipe (96), allow the two cylinders to be supplied with high pressure liquid in synchronism and thus to move the table. We can consider placing a larger number of cylinders if desired.

The continuation of operations continues as in the previous example. It is advantageous when the fabric is placed on the cutting table and is held by the pressers, to remove the slippery sheet carefully so as not to drag the fabric, move it or make folds. A variable speed motor will be used for rewinding the sliding sheet. We can in particular impose on the engine a speed-up program (from zero speed) to have a weak acceleration, a low speed. This avoids the entrainment of the fabric (or the formation of folds on the fabric) and the friction of the sliding sheet on the cutting table is reduced, therefore the wear of said sheet is reduced.

Claims

1. Method for placing a flat fabric coupon on a cutting table with a non-slip surface ensuring the precise permanence of the position of the fabric, characterized in that a sliding sheet is placed on the cutting table, that the fabric is precisely positioned on said sheet, that the fabric is immobilized by lateral pressing means and independently controlled radial pressing means, and that the sliding sheet is removed without moving the fabric. 2. Method according to claim 1, characterized in that the sliding sheet is on the one hand wound on a roller parallel to one of the sides of the cutting table and on the other hand stretched on the side opposite to the roller. 3. Method according to claims 1 and 2, characterized in that the cutting table is stationary during the establishment of the sliding sheet. 4. Method according to claims 1 to 3, characterized in that radial pressers immobilize the fabric without touching the sliding sheet. 5. Method according to claims 1 to 3, characterized in that lateral preseurs apply the fabric-sliding sheet assembly on the cutting table. 6. Method according to claim 3, characterized in that the sliding sheet comprises at its end opposite the roller a series of notches allowing the radial pressers to have contact only with the fabric, to apply said fabric to the upper side of the cutting table allowing the sliding sheet to be removed without moving the fabric. 7. Method according to the preceding claims, characterized in that the cutting table has a vertical movement controlled between a low position and a high position called working. 8. Method according to claim 7, characterized in that the vertical movement of the table is controlled by folding or unfolding a chisel. 9. Method according to claim 7, characterized in that the vertical movement of the table is controlled by a plurality of jacks placed on a horizontal crosspiece under the cutting table. 10. Device for implementing the method according to the preceding claims, characterized in that the sliding sheet is a polyester sheet and, preferably, a MYLAR sheet with a thickness less than 1 mm and, preferably, close 0.35 mm. 11. Device for implementing the method according to the preceding claims, characterized in that the radial pressers are constituted by pneumatic or electric cylinders. 12. Device according to claims 1 to 6, characterized in that, on each of the long sides of the table, a horizontal shaft is fixed on the frame parallel to said long side, that this shaft carries a series of cams, that the rotation d 'a fraction of a turn causes the cam to press the fabric and the reverse rotation releases the fabric. 13. Device according to claims 1 to 6, characterized in that the axis of rotation of the roller carrying the plastic sheet is subjected to a restoring torque by a counterweight or a spring. 14. Device according to claims 1 to 6, characterized in that the sliding sheet is held at the end opposite the roller by pliers, that each of these pliers is pulled by a chain driven by a pinion and that the two pinions are driven synchronously by a single motor shaft.