DE2147392A1 - Device for the automatic guidance of workpieces made of flat material - Google Patents

Description

Receive forwarding '

Dr.-lng. Dipl.-ing. G.

J. & P. Coats Limited in Glasgow (Great Britain)

Device for the automatic guidance of workpieces

made of flat material

The invention relates to a device for automatic guidance of workpieces made of flat material, for example to automatically produce a seam lengthways the edges of two workpieces or to carry out another operation, such as the Hemming the edges or adding ruffles. The workpieces can be fabrics or similar materials.

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The device according to the invention is particularly suitable for the production of items of clothing, wherein the material parts forming the item of clothing are connected to one another along an edge. The edges can be curved over at least part of their length.

The object of the present invention is, in particular, such a process to be carried out fully automatically perform, one workpiece at a time without Interruption is to be supplied.

It is already an automatically working guide device with a rotatable one at one end Guide rail has become known, which swings transversely to the feed direction to the sewing machine, with devices for sensing the edges, e.g. photocells, are provided to cause an oscillating movement of the guide rail in correspondence with the shape of the edge to be processed, a gripper movable along the guide rail is attached to the rear end of the workpiece and a revolving conveyor belt is provided, which in The conveying direction of the sewing machine revolves in order to lead the workpiece to the sewing machine. This device is for automatic Suitable for sewing individual workpieces in separate operations. This device is suitable however, it is not suitable for the automatic sewing of work

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pieces in one continuous operation, as the guide rail with its according to the shape of the edges oscillating movement at the point in time at which a new workpiece is to be supplied to assume a transverse position can, in which the task of a new workpiece after the previous workpiece is not possible is. Furthermore, the oscillating guide rail requires special attention from the operator to attach a gripper to this when each new workpiece is fed to the device.

The object of the present invention is to create a device which is suitable for removing the workpieces Automatically fed in rows in order to carry out a selected operation without switching off the machine.

A device according to the invention is characterized in that several grippers gripping the workpiece are slidably arranged along the guide rail against one end of the rail, at which end a support for the machine performing the operation is arranged, and a revolving conveyor belt delivered by the grippers Picks up workpieces and carries them on, with one strand of the conveyor belt parallel to the feed direction of the machine is arranged, and extends over the front and rear limits of the machine support, and that Facilities to open the gripper for the purpose of transferring the

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Workpieces are provided on the conveyor belt when moving the grippers approach the machine support, as well as devices for returning the grippers from the adjacent one the machine support arranged end to the other end of the guide rail.

The apparatus can also include a work piece tensioning device which is placed on the - Workpieces exert a force directed against the feed direction.

The conveyor belt is expediently driven.

The grippers can be provided with a coupling device, so that two adjacent grippers with one another can be connected.

Measures can also be taken to reduce the Connect the grippers to the belt when they reach the selected position and detach them from the belt again, when they leave the selected location.

Furthermore, a braking device can be provided for the belt.

The tensioning device can be a circumferential belt, which has a strand parallel to the feed direction the machine is arranged.

The clamping device for the workpiece can also be a brake shoe, which is attached to the selected

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th point is engaged on the guide rail.

Another embodiment of a tensioning device can be a braked, non-driven belt or at least one brake shoe with at least is in contact with a workpiece in the machine. A simple embodiment of the clamping device can be made from consist of a bundle of bristles which is pressed against the workpiece to be fed. This kind of jig has the advantage that it smooths the workpiece at the same time.

The connection of selected grippers with a strand of the tensioning belt can be mechanical or by Magnetic devices take place, e.g. the belt has plates of magnetic material, and the grippers the Wear magnets.

A pressing device can also be used which has a predetermined number of grippers is brought into engagement at the end of the guide rail remote from the machine support, and pushes this to the point of application on the guide rail, whereby a lever to be actuated by hand, the pressure device controls, and causes the gripper to close for gripping the workpiece at the loading point.

The pressing device can also include a pneumatically actuatable piston.

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A non-driven belt can be arranged below the referenced conveyor belt, the lower belt is designed so that it is attracted by a magnetized object. It can be stationary magnetic pole pieces are arranged near the opposite edges of the lower run of the conveyor belt be.

The magnetic pole pieces can be formed by two rails, one on either side of the lower one Runs of the conveyor belt are provided, with several horseshoe magnets arranged transversely to the conveyor belt and the Both pole faces of the magnets are each connected to a rail.

The horseshoe magnets can be suspended from a rigid support rod. Preferably the The support rod is arranged between the upper and lower run of the conveyor belt and the horseshoe magnets are on it the support rod, wherein the lower surface of the support rod is designed as a sliding surface, along which the lower run of the conveyor belt is movable.

Preferably the lower surfaces of the pole pieces are with respect to the surface of the lower run of the conveyor belt slightly set back.

The conveyor belt with the associated magnets and the lower belt can be built as one unit, which is vertically movable relative to the machine support.

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The device according to the invention can provide measures to a predetermined distance under several

/ to be provided for selected grippers at the loading point. This is preferably achieved »that .. a support rod is provided which is arranged to be movable to and fro parallel to the guide rail, ie in the feed direction of the workpieces and back» on which the adjusting devices are slidably attached, with each adjusting device only adjusting a gripper »When this is moved in the feed direction, and adjustable stops are arranged on the rod, which interact with the adjusting devices in such a way that all adjusting devices along the rod can slide freely against the end of the rod adjacent to the machine support, but each adjusting device along the Rod can slide to the opposite end away from the machine support only up to a stop assigned to this adjusting device ..

A preferred embodiment is that a releasable locking device is operationally with the pressing device is connected and with the first gripper, which is in a waiting position in front of the feed point is located, can be brought into engagement, so that the following grippers form a closed row and which locking device is released when a set of

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Grippers to be moved to the task point, and that a stop on the adjusting device engages when the support rod is moved in the opposite direction to the feed direction, wherein the locking device and the stop are relative

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are arranged to each other so that when a row of grippers is in the waiting position and the support rod is completely retracted, each adjusting device rests on the gripper assigned to it.
For gripping the workpiece by the gripper at the loading point, a rod is preferably provided which extends in the longitudinal direction to the loading point and can be moved against all grippers in the area of the loading point in order to actuate a closing device of the gripper.

The locking device which engages the front gripper and the rod for closing the grippers stands, can be operatively connected to a lever for actuating the pressing device.

In order to ensure that the adjusting devices slide freely over the entire support rod, but through the • assigned stop are stopped if they slide in a direction opposite to the conveying direction the device is preferably such that each stop has a part with a transverse extension, which is made progressively larger in each successive stop against the feed direction in relation to the previous stop and each setting

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Device has an open slot which is aligned with said parts of the stops, wherein the width of the slots in each successive adjusting device opposite to the feed direction of the Workpieces are progressively larger, with the width of the slots in each adjusting device being smaller, than the transverse extent of the associated stop part, but greater than the transverse extent of the preceding one Stop parts.

The machine for performing the desired work operation can, for example, be a sewing machine or be a machine for welding flat plastic parts.

When using a sewing machine, a cutting device can be used to cut the thread between 'The workpieces are provided at a point behind the needle, the cutting device, e.g. a photoelectric device, compressed air or compressed air or a suction device is operated, when the rear edge of each workpiece has left the sewing machine and is in a corresponding position for Cutting device comes.

The guide rail can have a return section

/the

own, which picks up the workpiece-releasing gripper .

The guide rail can be used as an endless loop

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be designed with two parallel parts, one of which leads to the machine support and the other forms the return section.

The guide rail can have a vibrating part which is arranged adjacent to the conveyor belt and swings across it. The oscillating movement can be controlled by signals from a measuring device,

/of
which measures the course of the edge on the workpiece to be machined. Such a device can be, for example, a photoelectric device or a compressed air or suction air device. In such an embodiment, the conveyor belt as a whole can also be arranged to swing in the transverse direction.

To release the engagement of the gripper on the workpiece can be a spring-loaded or gravity operable hook can be provided which is actuated when the gripper reaches the delivery point.

The grippers can be attached to the other end of the guide rail on their own inclined rail be guided downwards due to gravity or by a separate circulating gripper return belt. at In the latter embodiment, the guide rail, as already described, has the shape of an endless one Loop and the revolving return belt is arranged so that it engages the grippers on the return portion of the loop

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touched. The gripper return belt can by a Drive motor or driven by a foot pedal, which can also be used to close the gripper.

Devices can also be provided to hold one or more grippers in a corresponding position on the To arrange guide rail, which then the next following Capture workpiece. These facilities can

operated mechanically, electrically or pneumatically, with the corresponding control command by the last Gripper of a set is passed on when leaving the task area.

Similar devices can be provided around the gripper gripping the workpieces from the loading point to remove.

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214739 ^

The invention will now be further elucidated with reference to FIG Drawings described using an exemplary embodiment. In the drawings show:

1 shows a front view of a device according to the invention;

Fig. 2 is a plan view of the device;

Fig. 3 is a front view in relation to the

. Figures 1 and 2 on an enlarged scale showing the conveyor belt on the left-hand side of FIG.

FIG. 4 is a sectional view taken along line 4-4 in FIG.

Figure 5 is a front view of the support bar and the adjacent portion of the guide rail on the right Page viewed in Fig. 1.

FIG. 6 is a plan view of the support rod in the same position as in FIG. 5.

7, 8 and 9 the grippers gripping the workpiece, FIG. 7 being a front view of two side by side shows arranged and coupled together gripper; Fig. 8 is a plan view of the two grippers and Fig. 9 is a side view from the left in FIGS

10 shows the decoupling mechanism.

In the drawings, 1 denotes a frame which has a guide rail 2 in the form of an endless one Loop and a machine table 3 for one machine

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to carry out ? the desired work operation on the workpieces, the guide rail 2 being arranged parallel to the conveying direction .er machine attached to the table 3. In the exemplary embodiment shown, a sewing machine head and a feed mechanism 4 are arranged on the machine table 3, the work operation carried out being the hemming of edges of workpieces. A revolving conveyor belt is denoted by 5, the lower run of which runs parallel to the feed device of the machine 4 and which extends backwards and forwards over the part of the machine 4 which carries out the work operation, for example the needle. The conveyor belt 5 cooperates with an undriven lower belt 6. The lower belt 6 consists of a magnetized material and its upper run is close to the conveyor belt 5 and parallel to it. The lower run of the conveyor belt 5 is held in its position by a guide rail 7, the lower run of which slides along the lower surface of the rail as the conveyor belt rotates. On the guide rail 7 are seated horseshoe magnets 8, on the pole faces of which two rails 9 made of magnetizable material are attached. The rails 9 form magnetic pole pieces which are arranged on each side of the lower run of the conveyor belt 5. The lower surfaces of the rails 9 are arranged somewhat higher than the lower surface of the lower run of the conveyor belt 5.

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The conveyor belt 5 is driven by one or two toothed wheels 10 driven, which are drivingly connected to a motor (not shown).

The guide rail 2 carries a number of the workpiece gripping grippers Ί1, which along the Slide guide rail 2. With a revolving belt for returning the gripper is referred to, which is frictionally connected to the grippers along the return part 2A of the guide rail 2. With 13 is a pressing device referred to, which from the frame

I at the end of the facility on the right in Fig. 1 is provided, at the other end of the facility the working operation is carried out. The pressing device 13 is provided with a piston which is connected to a support rod 14 which is parallel to the guide rail 2 and above this can be pushed back and forth at the end of the task. The rod 14 carries a number of adjusting devices 15, which along the rod 14 Are slidably arranged and have resilient stops 16 with fixed abutments 17 on the top of the gripper

II can be brought into contact. On the pole 14 several stops 18 are attached in the form of bolts, its diameter from the end of the rod 14 near the conveyor belt 15 progressively in the direction opposite to Increase the conveyor belt. The position of the individual stops 18 on the rod H is adjustable. Parts of the adjusting device

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lines 15 are as the rod 14 enclosing tabs formed, with a gap 19 remaining between the ends of each tab, which gap with the stops 18 is aligned. The width of the gaps 19 in the successive actuators is determined by the end of the rod 14 adjacent to the conveyor belt 5 from progressively wider. The width of the column 19 and the diameter of the stops 18 are chosen so that when the rod 14 moves against the machine table 3 "each stop 18 with the corresponding adjusting device comes into contact, which has a sufficiently wide gap 19 to pass through to enable all previous stops 18, but is too narrow to this adjusting device to let through assigned stop. 20 denotes a fixed stop which corresponds to that of the conveyor belt the most distant actuator comes into contact. With a release lever is designated. The lever 21 has at one end a locking extension 22 and at the other end a finger 23 in order to be combined into groups To separate the gripper in turn, the locking extension 22 and the fingers 23 alternately in the path of movement of the adjusting devices 15 by pivoting the release lever 21 can be brought, wherein the pivoting of the lever 21 is initiated by a reciprocating movement of the rod 14 will.

As can be seen from FIGS. 6,7,8 and 9, each gripper 11 has a slide 24 which has a

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Needle 25 carries. The slide 24 is moved by a tension spring 26 down, so that the needle 25 of an upper fixed plate 27, which has an opening 28 aligned with the needle 25, is withdrawn. The slider 24 has a tongue 29 which can be brought into engagement with a pawl 30 designed as a detent. the The pawl is rotatable about the axis 31 and depends on it Dead weight downwards. On each gripper 11 is a

P coupling hook 32 rotatably attached, which has a decoupling tongue 33 owns. Furthermore, each gripper has a coupling pin 34, which with the coupling hook 32 of the adjacent gripper can be brought into engagement. 35 with an abutment is referred to, with which the tongue 33 of a gripper is brought into contact when the gripper is along the guide rail 2 during operation of the device to disengage the coupling hook 32 from the coupling pin 34 on the adjacent gripper to bring, whereby the gripper is decoupled.

At 36 an abutment is referred to which the lower end of each pawl 30 contacts when the gripper is longitudinal the guide rail is moved, with each pawl 30 swinging about the axis 31 and the engagement with the tongue 29 of the slide 24 is released. The lower end 24A of the pusher 34 extends below each gripper. A gripper locking bar 37 is connected to an actuating pedal 38, which also controls the pressing device.

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ert. The rod -37 can be moved in the vertical direction, so that each gripper arranged above the rod 37 can be connected by actuating the pedal 38, wherein the rod 37 can be guided against the lower end 24A of the slide 24, whereby the slide 24 is raised until the tongue 29 comes to lie above the associated pawl 30, which is then due to their own weight.under the tongue 29 swings and holds the slide 24 in the raised position in which the needle 25 of the opening 28 of the plate 27 is located.

With 39 a bristle bundle is referred to, which is pressed against the supplied workpiece, wherein the bristle bundle 39 is used for tensioning and smoothing the workpiece, especially the rear edges. With a workbench 40 is referred to, which is used to provide the workpieces.

The operation of the device is as follows: The first workpiece, which is for example a piece of fabric or a piece of plastic can be placed on the table 40 and the gripper 11, which is attached to the guide rail 2 are attached at intervals on the edge of the workpiece to be hemmed. The front end of the Workpiece is introduced into the machine 4 producing the seam and the machine is put into operation. The material is fed to the machine 4, the feed mechanism

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Mus and the conveyor belt 5 pull the material into the machine 4 and cause the grippers 11 to slide along the guide rail 2. Successive workpieces are arranged one behind the other, each workpiece being fastened to the previous workpiece by means of two grippers 11 (see Fig. 7), which connect the adjacent ends of the two workpieces with one another, so that the seaming can be carried out continuously, the workpieces without interruption can be fed to the seaming machine. When a gripper approaches the seaming machine, it is opened with the release of the workpiece and moves to the return part 2A of the guide rail 2 and leads from the belt 12 back to the feed end of the guide rail 2, where it grips the same or another workpiece. Since a pair of grippers 11, which connect two successive workpieces to one another, are fed to the machine 4, the device for opening the grippers is actuated. This releases the connection between the two adjacent ends of the workpieces. At this point, however, the conveyor belt 5 has the effect that the leading end of the following workpiece is fed to the feed mechanism of the machine 4, so that there is no standstill. The cutting device is actuated when the rear end of each workpiece has passed through the sewing machine, where-

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in which the thread is severed between the successive workpieces.

The mode of operation of the individual parts will now be explained in more detail: To get the grippers 11 at the feed point, i.e. to keep at a distance from one another on the table 40 when the grippers 11 pass through the return part 2A of the guide rail 2 are performed in their waiting position, the locking extension 22 is in a position in which he the stops at the front open gripper, with the following grippers hitting the first gripper and a closed one Form a row of grippers in the waiting position (see Fig. 6), in which the locking extension 22 is in the raised position shown and the grippers are ready for operation). When the operator depresses the pedal 38 after the last feeding pass has actuated, the support rod 14 has been

/ s table 40 is withdrawn and with it the adjusting device. The first locking device is against the stop 20 and remains in this position even if the rod 14 is withdrawn even further (in FIG. 5 to the right), whereby the following adjusting devices are lined up touching one another. Since the width of the Gap 19 of each adjusting device 15 is greater than the diameter of all the stops 18 located behind it in the opposite direction to that of the machine table 3, each adjusting device 15 can be moved behind all of the stops 18 located behind it when the

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Rod I4 is withdrawn from machine table 40, i. in a direction opposite to the conveying direction of the workpieces. All actuating devices are thus switched on one end of the support rod 14 near the table 40

t r

pushed together. The adjusting devices 15 are dimensioned so that they are more open-minded and withdrawn Position with the rod 14 completely retracted touch the associated gripper 11, which in a row are arranged in waiting position (see right side of Fig. 5).

If the operator 38 presses the pedal down to initiate a new cycle, the rod 37 is raised and thereby presses all the slides 24, the grippers arranged along the table 40, upwards during the last feed operation of the pressure device and thus lifts the needles 25 in the openings 28 of the plates 27 and causes the grippers to grip a workpiece which has previously been inserted into the grippers between the slides 24 and the plates 27 by the operator. After lifting the slide 24, the pawls 30 fall under their own weight under the tongues 29 and thereby keep the grippers closed after the operator has released the pedal 38, causing the rod 37 to clear the way. The Arre animal extension 22 is withdrawn, whereby the lined up gripper are released. If the

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Pressing device 13 is actuated to start the feeding process initiate. When the support rod 14 is moved in the feed direction, each actuator pushes 15 their associated gripper 11 along the guide rail 2 in front of you. The friction of each gripper 11 on the guide rail 2 makes the pressure of the associated Stop 16 resistance and the adjusting device 15 remains stationary, with the advancing rod I4

slides in the actuators. Each stop 18 on /is

the rod 14 with a transverse extent smaller than the width of the gap 19 is passed through the gap 19 until a stop 18 reaches a gap 19, the width of which is smaller than the transverse extent of the corresponding stop 18, whereby the associated adjusting device is pushed forward with the support rod I4. In this way, the actuators with the associated grippers with the rod I4 in a position above of the table 40, the individual grippers from one another at a distance defined by the stops 18 are arranged (see left side of FIGS. 5 and 6). Is the front gripper by the adjusting device It is pushed forward in the direction of the feed point with the last gripper of the previous one Set coupled by connecting the coupling hook 32 of the front newly supplied gripper with the Coupling bolt 34 of the last gripper of the previous one

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Sentence. This last gripper is already at the loading point and the workpiece is currently being processed into it. inserted. These two grippers are then brought into the position shown in FIGS.

By continuously moving the rod in the direction of the table 40, the grippers 11 are through the Adjusting devices 15 for the task point and the workpiece already gripping gripper of the previous set along the guide rail 2 in the direction of the machine table 3 pushed. The workpiece gripped by the previous set of grippers is in a zjdaarmonika-like shape compressed when the grippers engaging the workpiece are pushed together, but this is not disadvantageous, because the grippers have already gripped the workpiece at specified intervals. If now the workpiece through the conveyor belt is pulled against the machine 4, the workpiece is due to the gripper on the neighboring The ends of the workpieces are smoothed. Although the gripper at the rear end of the corrugated workpiece and the front Gripper of the new gripper set supplied to the feed point

are coupled, the time required to smooth the workpiece is sufficient to make it to the operator to enable a new workpiece to be inserted into the gripper on the table 40 to initiate a new operation, wherein the grippers gripping the workpiece are pushed away from the table 40 and a new set of grippers

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remote to initiate another work step is pushed to the task point. As soon as the locking extension 22 is lifted from the row of waiting grippers in order _{to enable the (i} grippers to move forward), the finger 23 moves behind the gripper set in order to prevent the following grippers from moving forward.

The stationary magnetic pole pieces 9 attract the upper run of the lower belt 6 and cause that the upper run of the lower belt 6 is pressed against the lower run of the conveyor belt 5. Every on Conveyor belt 5 incoming workpiece is passed between the lower belt 6 and the conveyor belt 5 and thus wedged between the belts 5 and 6 and taken along with the conveyor belt 5 due to the frictional Connection between the lower belt 6 and the workpiece between the workpiece and the conveyor belt 5.

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Claims (20)

Patent claims: 1. / Device for automatic feeding of pieces made of flat material with a guide rail and a gripper which engages the workpiece and moves along the rail and guides the workpiece to the processing point, characterized in that a plurality of grippers gripping the workpiece are slidably arranged along the guide rail against one end of the rail, at which end a support for the machine performing the operation is arranged, and a rotating conveyor belt picks up and continues workpieces released by the grippers, a strand of the conveyor belt being arranged parallel to the feed direction of the machine, and extending over the front and rear limits of the machine support, and that devices for Ö ££ NEN the gripper are provided for the purpose of transferring the workpieces to the conveyor belt when the grippers approach the machine support, as well as devices for returning the grippers from the end arranged adjacent to the machine support to the other end of the guide rail. 2. Device according to claim 1, characterized in that that the conveyor belt is driven. 3. Device according to claim 1, characterized 209824/0899 draws that a clamping device is provided for the workpieces, which one counter to the workpieces the direction of feed exerts force. 4. Apparatus according to claim 1, characterized in that the gripper is provided with a coupling so that two adjacent grippers can be connected to one another. 5. Apparatus according to claim 3, characterized in that that the clamping device is formed by a bundle of bristles which against the workpiece to be fed is compressible. 6. Apparatus according to claim 1, characterized in that that a pressing device is provided, which with a predetermined number of grippers on the ' apart from the machine support end of the guide rail is brought into engagement and this to the task point presses on the guide rail. 7. Apparatus according to claim 6, characterized in that that a manually operated lever controls the pressure device and a closing of the gripper for detecting the workpiece causes the task point. 8. Apparatus according to claim 1, characterized in that that a non-driven lower belt is arranged below the driven conveyor belt. 9. Apparatus according to claim 6, characterized 209824/0899 draws that to maintain a predetermined distance a support rod is provided under several selected grippers at the task point, which parallel is arranged to be movable back and forth to the guide rail, i.e. in the feed direction of the workpieces and back which the adjusting devices are slidably attached, each adjusting device only adjusting a gripper when this is moved in the feed direction, and adjustable stops are arranged on the rod, which cooperate with the adjusting devices in such a way that all adjusting devices are free along the rod can slide against the end of the rod adjacent to the machine support, but each adjusting device along the rod to the opposite end away from the machine support only up to one of these Adjusting device associated stop can slide. 10. Apparatus according to claim 6, characterized in that that a releasable locking device is operatively connected to the pressing device and with the first gripper, which is in a waiting position in front of the loading point, can be brought into engagement can, so that the following grippers form a closed row and which locking device is released, if a set of grippers is moved to the feed point by moving the support bar in the feed direction 209824/0899 the should, and that a stop engages the adjusting device when the support rod is opposite to the feed direction is moved, wherein the locking device and the stop are arranged relative to each other so that that in the presence of a number of grippers in the waiting position and the support bar fully retracted, each adjusting device rests on its associated gripper. 1 1. Device according to claim 1, characterized in that that a rod is provided for gripping the workpiece by the gripper at the loading point, which extends in the longitudinal direction to the feed point and against all grippers in the area of the feed point is movable to actuate a closing device of the gripper. 12. The device according to claim 9, characterized in that that each stop has a part with a transverse extension, which in each successive Stop running against the feed direction in relation to the previous stop progressively larger and each actuator has an open slot which is aligned with said portions of the stops is, the width of the slots in each successive adjusting device opposite to the feed direction the work piece is progressively larger, with the width of the slots in each adjusting device being smaller, as the transverse extension of the associated stop part, 209824/0899 but larger than the transverse extensions of the preceding stop parts. 13. The device according to claim 1, characterized in that that the guide rail has a return section possesses, which picks up the gripper releasing the workpiece. 14. Apparatus according to claim 13, characterized in that the guide rail is an endless loop is formed and has two mutually parallel sections, one of which leads to the machine support and the other forms the return section. 15. The device according to claim 14, characterized in that that a belt grabs the gripper when it enters the return section and returns it to the leads away from the machine table end of the guide rail. 16. The device according to claim 1, characterized k indicates that each gripper has one with the guide rail engaging part and a workpiece engaging part, the latter part having one with a plate provided with an opening has a slide carrying a needle, the opening with the needle is aligned and the slide is slidable between two positions, one of which is closed Corresponds to the position of the hook in which the needle point is located inside the opening and the work- 209824/0899 piece is pierced by the needle, and the other position corresponds to the open hook in which the The needle is pulled out of the opening and the slide is pressed into the open position by a spring. 17. The device according to claim 16, characterized in that the slide has a tongue and an am first gripper part has rotatably arranged pawl which can be brought into engagement with the tongue, whereby the slide is held in the closed position of the gripper against the pressure of the spring. 18. The device according to claim 16, characterized in that a rotatable coupling hook and on the gripper a coupling pin is arranged, the coupling pin with the coupling hook of the following gripper can be brought into engagement and the coupling hook has a decoupling tongue. 19. The device according to claim I7, characterized in that that a fixed stop with the pawl of each gripper in a predetermined adjustable position of the Gripper can be brought into engagement on the guide rail to return the latch from the tongue and the The spring retracts the slide, which pulls the needle back out of the opening and thus opens the looper will. 20. The device according to claim 18, characterized in that a fixed stop is provided which 2Q982W0899 can be brought into engagement with the decoupling tongue in a predetermined adjustable position of the gripper on the guide rail to remove the coupling hook from the coupling pin of the following gripper r ι to withdraw. 209824/0899 Blank page