PLATE MANIPULATION

The invention relates to a method for manipulating a plate during processing thereof with a processing station having an upper beam and lower beam movable toward each other. A processing station with upper beam and lower beam movable toward each other is for instance a folding press or shears. In such processing stations there are arranged in the upper beam and lower beam different tools with which a plate, such as a steel plate, can be shaped or cut.

In manual operation of such a processing station the operative will manipulate and arrange the plate in the desired manner in the processing station so that the necessary operations can be performed. The operative must here take into account the dimensioning and accuracy of the processes to be performed.

Such manual operations are usually automated to thus enable a higher precision and a higher throughput speed. Placed for this purpose in front of a processing station is a robot arm which engages and subsequently places the plate between the upper beam and lower beam in order to thus perform the desired processes. As long as the engagement of the robot on the plate does not change, the control of the robot can place the plate at all times with the desired precision in the processing station. However, as soon as the engagement must be released, for instance because the plate must be rotated and the robot must engage on another part , the robot must then first calibrate the position by laying the plate against two fixed surfaces, so that the robot can

once again compute the origin. Further operations can then be performed. Such an interim calibration takes time.

Another drawback of performing operations from one side of the processing station is that the feed of plates and the discharge of processed products is difficult to fit into the logistic system. A material flow from the front to the rear is often desirable, while in an above described processing station with robot arm the material flow normally takes place at the front of the processing station. This represents a limitation, certainly in view of the limited reach of a robot arm in combination with required buffers.

It is now an object of the invention to provide a method which alleviates, or even obviates, the above stated drawbacks.

This object is achieved with a method according to the invention which comprises the steps of:

- providing a plate; - engaging the plate at a first point of engagement ;

- positioning the plate between the upper beam and lower beam from a first side for the purpose of performing operations on the plate with the processing station; and

- carrying the plate between the upper beam and lower beam from the first side to the opposite other side.

By now engaging the plate at a first point of engagement and first positioning the plate between the upper beam and lower beam from a first side and subsequently carrying the plate between the upper beam and lower beam to the opposite other side, further operations can there be performed without the point of engagement on the plate having to be changed. This

moreover provides the further advantage that the processing station can be placed in line more readily with the material flow, wherein the feed takes place on the first side of the processing station while the discharge takes place on the other side.

A preferred embodiment of the method according to the invention comprises the step of positioning the plate between the upper beam and lower beam from the other side for the purpose of performing operations on the plate with the processing station. Because the plate, held fast at the first point of engagement, is now situated on the other side of the processing station, the movement options are mirrored, whereby more options for processing the plate are available. Yet another embodiment of the method according to the invention comprises the step of releasing the engagement of the first point of engagement.

A further preferred method according to the invention comprises the step of engaging the plate at a second point of engagement. By engaging the plate at a second point of engagement the calibration can be retained since the plate is also being held fast at the first point of engagement. Once the plate is held fixedly at the second point of engagement, the first point of engagement can optionally be released. This creates additional possibilities for manipulation and processing of the plate.

It is further possible to use both points of engagement so that elongate products can hereby be processed easily. Possible sagging as a result of the length can hereby be reduced or even prevented. In yet another embodiment of the method according to the invention the manipulation of the plate is synchronized with the movements of the upper beam and lower beam of the processing station. In for instance a

folding press the plate will bend and outer ends will be displaced relative to the processing station while the upper beam and lower beam move toward each other. It is desirable here to synchronize the manipulation of the plate with the movement of the upper beam and lower beam, so that undesired bending of the plate is prevented.

The invention further comprises a device for performing the method according to the invention, which device comprises:

- a processing station with upper beam and lower beam movable toward each other, wherein tools are arranged on the upper beam and lower beam;

- a first manipulator arranged on a base, this base being displaceable between the upper beam and lower beam from a first side to a second opposite side.

Because the first manipulator is arranged on a base which is displaceable from the first side to the other side of the device, the plate can hereby be carried easily between the upper beam and lower beam from the one side to the other side.

A preferred embodiment of the device according to the invention comprises a second manipulator arranged on a base, this base being displaceable independently of the first manipulator between the upper beam and lower beam from the first side to the second opposite side. With this second manipulator it is possible for instance to perform preparatory operations, such as the calibration of the plate, after which the plate can be taken over by the first manipulator, although it is also possible to jointly process elongate products. In addition, it is optionally also possible to have both manipulators manufacture products simultaneously from the plates, wherein the operations of the two manipulators are synchronized with the movements of the

upper beam and lower beam. The production of such a processing station can thus be increased considerably.

In a further preferred embodiment of the device according to the invention the manipulator is a robot arm. Such a robot arm provides many degrees of freedom, thereby enabling optimum manipulation of the plate.

These and other features of the invention are further elucidated on the basis of the accompanying drawings . Figure 1 shows a perspective view of a device according to the invention.

Figures 2A-2D show schematically four different steps of the method according to the invention.

Figure 1 shows a folding press 1 with a fixed upper beam 2 in which tools 3 are arranged, and a displaceable lower beam 4 with tools 5 therein. Arranged on either side of upper beam 2 and lower beam 4 are guides 6, 7 on which is arranged a displaceable base 8, 9 respectively having thereon a robot arm 10, 11. Each robot arm 10, 11 has a gripper 12, 13 with which a plate 14 can be held fast. Figure 1 shows the embodiment wherein both robot arms 10, 11 together hold one plate 14. As already stated above, is also possible to have one of the robot arms 10, 11 carry out preparatory operations or to have each carry out the same bending operations simultaneously on a separate plate.

Figure 2A show schematically a first step of the method according to the invention. The schematic parts are here indicated with the same reference numerals as in figure 1.

In figure 2A the base 8 of robot arm 10 is displaced wholly to the left on guide 6. Using gripper 12 the robot arm 10 holds a plate 14 against tool 3 in the fixed upper beam 2.

The displaceable lower beam 4 with tool 5 is then moved upward so that plate 14 (see also figure 2B) is bent. As a result of the bending the point of engagement of gripper 12 on plate 14 will have to be moved in order to prevent undesirable bending of plate 14. By synchronizing the movement of lower beam 4 and robot arm 10 it is possible during bending of plate 14 to follow this plate with robot arm 10.

Lower beam 4 is subsequently moved downward again so that base 8 with robot arm 10 and the plate 14 arranged thereon can be displaced between upper beam 2 and lower beam 4 over guide 6 to the other side. It is thus possible to once again arrange plate 14 against upper tool 3 and bend an angle therein in the opposite direction without rotation around gripper 12, as shown in figure 2D. Lower beam 4 is then moved downward again and the bent plate part 14 can be set down in a discharge buffer on the side where robot arm 10 is situated, or the plate can once again be displaced between upper beam 2 and lower beam 4 in order to be set down again on the first side.