The present disclosure relates to methods for loading blanks to a head press of a stamping press line, and to systems thereof.

BACKGROUND

In the production of stamped or pressed metal parts, stamping press lines may be supplied with metal blanks that have previously been cut from a metal coil in a separate blanking line. The blanks may be shear-cut metal blanks of a predetermined length or they may be contoured blanks cut with a blanking die.

The use of industrial robots for picking blanks from a stack at a pick-up position and loading them in a stamping press line, such as those for manufacturing vehicle body parts is known.

In known systems, a first industrial loading robot collects the blanks from a stack of blanks. The blanks at the top of the stack e.g. blanks made of magnetic material may be maintained slightly separated from each other at least at the edges, for example by means of magnets, to prevent them from adhering to each other and thus preventing the first loading robot from picking more than one blank, which would cause serious problems.

The first industrial robot situates the blank located at the top of the stack in a centering station e.g. a gravity table to get the blank centered. Alternatively, the blank may be located using e.g. a vision system. A second industrial loading robot collects the centered or located blank and feeds the blank to the head press of the stamping press line. Centering or locating of the blanks is generally required because the stacks of blanks may be inaccurately placed in the pick-up position by a forklift truck, and also because of the inaccurate position of the stack on the supporting element e.g. pallet which doesn't allow for the accuracy needed to load the blank into a press. With this arrangement, at least two industrial robots and a centering device are required for the de-stacking and loading operation. In low cost and / or low output rate requirement cases, it might be desirable to provide a simpler solution that allows working with a single loading robot, and at the same time removing the need for a costly centering or locating system.

SUMMARY

In a first aspect, a method for loading blanks from a stack of blanks to a head press of a stamping press line is provided. The method comprises: providing a loading robot; providing one or more separating robots configured to separate one blank at the top of a stack of blanks from the underlying blanks; providing a stack of blanks and applying separating robots to at least one side of the stack; recognizing the position of the stack of blanks using the position of the separating robots; picking up the blank located at the top of the stack of blanks with the loading robot, using the recognized position of the stack; loading the blank to the head press of the stamping press line using the loading robot.

According to this first aspect, the position of the stack of blanks is recognized using the position of the separating robots. The movement of the loading robot may be adapted in order to pick up the blank from the right recognized position of the stack of blanks. In this way, the loading robot is capable of loading the blank to the correct position at the head press of the stamping press line. Therefore, the picking position will be, normally, different for each stack, while the dropping position into the head press will be always the same. With this arrangement, a single loading robot can be used. Furthermore, the use of some other centering element e.g. a centering table in order to get the blank centered or location systems e.g. a vision system is avoided, thus there is a substantial cost saving. In addition, the space used near the head press of the production press line may be optimized since only a single robot is required near the head press of the stamping press line. The separating robots may be used to separate one blank at the top of the stack of blanks from the underlying blanks and to recognize the position of the stack of blanks, thus the use of the robots may be optimized due to the fact that different functions may be carried out by the same robots. In a second aspect, a system for loading blanks to a head press of a stamping press line is provided. The system comprising a loading robot and one or more separating robots; each separating robot comprises one or more separating tools configured to separate one blank located at the top of the stack of blanks from the underlying blanks. Furthermore, the separating robots are arranged to recognize the position of the stack of blanks, and to provide the recognized position to a loading robot.

BRIEF DESCRIPTION OF THE DRAWINGS Non-limiting examples of the present disclosure will be described in the following, with reference to the appended drawings, in which:

Figure 1 is an illustration of a block diagram describing an example of a method for loading blanks to a head press of a stamping press line,

Figure 2 is a perspective view of a loading station of a head press of a stamping press line with an embodiment of a system for picking and loading blanks, Figure 3 is a perspective view of the loading station showing a loading robot of the system picking up a blank located at the top of the stack of blanks, Figure 4 is a perspective view of the loading station showing the robot moving the blank towards the head press of the stamping press line, and

Figure 5 is a perspective view of the loading station showing the robot loading the blank to the head press of the stamping press line.

DETAILED DESCRIPTION OF EXAMPLES

Figure 1 is an illustration of a block diagram describing an example of a method for loading blanks to a head press of a stamping press line.

At block 101 , a loading robot may be provided. At block 102, one or more separating robots configured to separate one blank located at the top of the stack of blanks from the underlying blanks are provided. At block 103, a stack of blanks may be provided and the separating robots may be applied against at least one side of the stack of blanks.

At block 104, the position of the stack of blanks may be recognized using the position of the separating robots. Then, at block 105, the blank located at the top of the stack of blanks may be picked up with the loading robot using the recognized position of the stack, such that the loading robot may pick up the blanks in an accurate way, taking into account the position of each stack of blanks, without the need for a centering or locating system. With this arrangement, at block 106, the blank may be properly picked and loaded in the desired position to the head press of the stamping press line.

Moreover, the use of a second robot may be avoided. Other centering or locating solutions are also avoided such as centering tables or vision systems.

Figure 2 shows a system for picking and loading blanks according to an embodiment of the invention, in a loading station of a head press of a stamping press line.

More particularly, figure 2 shows very schematically a head press of a stamping press line 2, which may receive a blank 3 from a stack 4 of blanks located at a pick-up position 5.

A loading robot 6, for example a suitable industrial robot, may be used to feed the press line 2. The stack 4 of blanks may be located on a stacking support 7 configured to hold the stack of blanks. The stacking support 7 is shown only schematically in this figure, and may be of any known type.

The stacking support 7 may comprise a carriage 8 which may be displaceable along a track (not shown). The carriage 8 may be driven by a linear motor (not shown) but other options may be possible. The stacking support 7 may be provided with load detecting means (not shown) to detect that the stack 4 of blanks is exhausted, or that only a predetermined number of blanks remain.

The loading robot 6 may have at least four axes. The loading robot 6 may comprise a tooling 9 with suction cups suitable for handling the blank although in some other embodiments the tooling may comprise e.g. magnets suitable for handling the blank 3. The tooling 9 may be attached at the distal end of the loading robot 6. The loading robot 6 is schematically shown mounted on the floor but some other configurations may be possible, e.g. roof or shelf mounted.

An example of a loading robot that may be employed in the loading station of all the figures is robot IRB 6650S, available from ABB (www.abb.com), with an additional rotational 7 ^th axis, among other robots. The loading robot 6 may have a first base of coordinates e.g. an absolute base of coordinates. The first base of coordinates may have its zero point in the base of the loading robot. A loading point, which is the point suitable for properly load the blank to the head press of stamping press line is defined in the first base of coordinates. The loading point into the press line defined in the first base of coordinates must be the same for every stack of blanks that is placed at the pick-up position 5 and it is suitable to be loaded to the head press of the press line.

The loading robot 6 may be controlled by control means (not shown) to program a pick-up point, pick up the blank 3 at the top of the stack 4, and load it at the previously defined loading point on the head press of the stamping press line 2 in the correct position. As will be commented further below, the loading robot 6 may use a second base of coordinates e.g. a temporal base of coordinates which is based on the position of the stack of blanks and therefore is different for each stack of blanks that is placed at the pick-up position 5 and it is configured to be picked and loaded by the loading robot 6τ

The position of the stack of blanks may be recognized and transmitted to the loading robot 6 by, for example, a plurality of separating robots. The position of three points will be sufficient to recognize with enough accuracy the position of the stack. For very simple blanks, such as rectangular blanks, one or two robots may be enough; in most common cases more than three separating robots may be convenient.

The pick-up point for the blanks may be defined in the second base of coordinates, thus the blanks of the stack may be correctly and picked up with enough accuracy at the right position, account being taken of the differences in position between one stack and another, and then loaded to the head press of the press line.

The system for picking and loading blanks may comprise one or more separating robots, in order to separate one blank at the top of the stack from the underlying blanks: this prevents the loading robot from picking up more than one blank, and avoids the risk of the loading robot loading two or more blanks to the head press of the press line, thus causing serious problems to the press line. In some examples, the loading robot may be equipped with a double blank detector in order to avoid taking more than one blank. In the embodiment shown in Figure 2 the system for picking and loading blanks comprises four separating robots 10a, 10b, 10c and 10d.

Throughout the present description and claims the term "separating robots" is to be understood as encompassing industrial robots which are defined as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes or manipulators with at least two degrees of freedom.

An example of an industrial robot suitable to be employed as separating robot in such a handling system is IRB 260, IRB 1200 or IRB 1600, available from ABB (www.abb.com), among others.

Each separating robot 10a, 10b, 10c and 10d may be provided with a separating tool 13, e.g. a magnetic device provided at its distal end. The magnetic device creates a magnetic field, thus the blank situated on the top of the stack may be slightly separated from the underlying blanks of the stack of blanks 4. In some alternatives, the separating tool may be a blower tool configured to inject air between the blanks, or may combine both a magnetic and a pneumatic effect. The separating tool may be applied against one side or two sides of the stack 4 of blanks.

In the particular case of the separating tool applied against two sides, the separating robot (and thus the separating tool) may be located at or near the vertex defining the intersection of two sides of the stack of blanks. With this arrangement, the separating tool may be applied at the same time against two sides of the stack of blanks. By the use of the separating tools, the blank at the top of the stack 4 that is prepared to be picked by the robot 6 may be slightly separated from the second blank, usually along its edges As commented above, the separating tool may be magnetic but other embodiments are possible. For example, in the case of blanks on nonmagnetic materials such as aluminum, the tool may inject air between the blanks to separate them. Another option may be to apply a mechanical friction force on the upper edge of the blank that is at the top of the stack, so as to lift it slightly, in this case, the mechanical friction may be applied to both magnetics and non-magnetics blanks.

The plurality of separating robots 10a, 10b, 10c and 10d may be controlled jointly, such that the separating robots may act simultaneously on the blank(s) to separate it from the stack of blanks 4.

Control units that may operate robots jointly are for example those available from ABB (www.abb.com) which include the function MultiMove; MultiMove is a function embedded e.g. into ABB's IRC5 control module, that allows to control the axes of several manipulators such that they work like a single robot.

The position of the stack of blanks may be recognized by determining the tool center point (TCP) of the separating tool of each separating robots 10a, 10b, 10c, 10d. The tool center point (TCP) is the point in relation to which all robot positioning is defined. The tool center point is defined as X, Y, Z distance relative to a robot wrist of each separating robot. With this arrangement, the tool center point may coincide with, for example, the magnetic device provided at each separating robot. This way, the position of the tool center point (TCP) (and thus the separating tool) may be recognized, thus the position of the stack of blanks may also be recognized. In further examples, a sensor system (not shown) may be provided to recognize the actual position of the stack of blanks, for example its X, Y and Z coordinates and its angular position. For example, the sensor system may be arranged at or near the separating tool of each separating robot. This way, when the separating robots 10a, 10b, 10c, 10d (and thus the separating tool of each separating robot) are applied against the stack 4 of blanks, the position of the sensor itself (and thus the position at or near the separating tool) may be sensed, thus the position of the stack of blanks may also be recognized. In yet further examples, the sensor system may be located in some other suitable locations on the separating robots.

In this particular example, the separating robots 10a and 10b are applied against one side of the stack of blanks and the separating robots 10c and 10d are applied against the opposite side of the stack of blanks, although some other configuration of the layout of the robots against the stack of blanks may be possible.

The system may also have the appropriate control and/or output units to calculate from the readings of the sensors the actual position of stack of blanks and to transmit this information to the loading robot 6.

The actual position of the stack of blanks may be recognized by the separating robots 10a, 10b, 10c, 10d. This information may be transmitted to the loading robot. The loading robot may use the information transmitted by the separating robots to generate a second base of coordinates. With this arrangement, a pick-up point where the blank located at the top of the stack has to be picked up may be defined.

In this particular example, the stack 4 of blanks may be one stack of blanks although some other options may be possible. For example, the stack of blanks may be formed with a plurality of stacks of blanks. In this way, the plurality of stacks of blanks may be situated on the stacking support. The plurality of stacks of blanks may be situated parallel to each other in the direction of the flow of the press stamping line although some geometrical distributions may be possible. In the particular case of two stacks of blanks, the operation of the system may be described as follows: the position of a blank at the top of the first stack and the second stack may be determined. The position of the blank at the top of the first and second stack may be provided to the loading robot. A default coordinate system of the loading robot may be corrected creating a temporal coordinate system based on the positions provided. The loading robot may pick up a first blank situated at the top of the first stack of blanks and a second blank situated at the top of the second stack blanks simultaneously. The stamping press line may be fed with the first and second blanks at the same time and in the right position (centred), thus the feed rate of the line may be increased with high accuracy as to the positioning of the blank. The blanks of the plurality of stacks can also be taken independently. In this case, different temporal coordinate systems will be used for each stack.

One embodiment of the method for loading blanks to the head press of the stamping press line 2 that employs such a system for picking and loading blanks will now be described in more detail with reference to Figures 2 to 4.

In Figure 2, the loading robot 6 is moving towards the stack 4 in order to pick up a blank 3. The plurality of separating robots 10a, 10b, 10c and 10d may have the separating tools 13 activated, thus the blank situated on the top of the stack 4 of blanks may be maintained slightly separated. As blanks are removed from the stack 4, and unless the stacking support 7 is provided with a lift, the height of the stack 4 will decrease; the separating robots 10a, 10b, 10c, 10d may then progressively adjust the position of the separating tools 13 to the stack 4 height.

The number of blanks remaining on the stack 4 may be controlled, for example by means of a load detector (not shown); alternatively, the number or remaining blanks may be determined depending on the height of the separating robots 10a, 10b, 10c, 10d, because these robots place the separating tool adjacent the blank at the top of the stack, so their height at any time depends on the number of remaining blanks.

Each separating robot 10a, 10b, 10c and 10d may recognize one position i.e. the coordinates of one point of the stack of blanks. The position may be recognized at each separating robot, for example, by sensing the position of the separating tool e.g. a magnetic device or one or more additional sensors (not shown) arranged at or near the separating tool when the separating robots (and thus the magnetic device) are applied against al least two sides of the stack of blanks.

In this example, the separating robots 10c and 10d are applied against the one side of the stack 4of blanks and the separating robots 10a and 10b are applied against the opposite side of the stack 4 of blanks.

In some other examples, the position of the stack of blanks may be recognized by determining the tool center point (TCP) of the separating tool of each separating robots 10a, 10b, 10c, 10d.

In this particular example, the separating robots 10a, 10b, 10c and 10d may use a same sensing arrangement e.g. one or more sensors (not shown) arranged at or near the magnetic device although some other configurations may be possible, for example, the separating robots 10a, 10b may use one sensing arrangement e.g. one or more sensors (not shown) arranged at or near the magnetic device and the separating robots 10c and 10d may recognize the position of the blank by determining the tool center point. The position recognized by the separating robots may be a plurality of spatial points of the stack of blanks. The spatial points may correspond to the coordinates X, Y, Z of the blank located at the stack of blanks and the orientation of the blank in the horizontal plane.

Once the position of the stack 4 of blanks is recognized using the position of the separating robots 10a, 10b, 10c, 10d said position may be provided to the loading robot 6. The physical transfer of data may be over a point-to-point communication channel. Examples of such channels may be copper wires, optical fibres, wireless, etc... The control system of the loading robot 6 then uses a second base of coordinates on the basis of the position of the points of the stack of blanks as recognized by the separating robots 10a, 10b, 10c, 10d. The pick-up point where the blanks have to be picked may be defined in this second base of coordinates.

This way, the loading robot 6 is able to properly pick up the blank e.g. a blank from a skewed stack 4 of blanks at the pick-up point. As will be further commented, the loading robot 6 must properly position the blank relative to the desired position to be loaded to the head press of the stamping press line.

Figure 3 shows the system picking up a blank located at the top of the stack of blanks. As commented above, the loading robot 6 uses a second base of coordinates on the basis of the position of the points of the stack of blanks recognized by the separating robots. A pick-up point in order to pick up the blank located at the top of the stack may be defined in this second base of coordinates With this pick-up point, the loading robot 6 may correctly pick-up the blank located at the top of the stack.

The stacking support 7, once the stack is emptied may be displaced from the pick-up position 5. The empty stack of blanks may be replaced with a new stack (not shown) of blanks, which may be prepared at one side of the pick-up position 5. The new stack of blanks may also be disposed on a new stacking support and carriage. The new stacking support with the new stack of blanks may be displaced towards the pick-up position at the same time as the empty stacking support removed from said position. Figure 4 is a perspective view of the loading station showing the robot moving the blank towards the head press of the stamping press line. As commented above, the loading robot has a first base of coordinates. A loading point for loading the blanks to the head press of the press line may be defined in this first base of coordinates, and it must be the same loading point for different stacks of blanks, regardless of their positioning.

The loading robot 6 may pick up the blank 3 located at the top of the stack 4. Then, the loading robot 6 (and thus the blank 3) may be moved towards the loading point defined in the first base of coordinates of the loading robot located at the head press 2 of the press line where the blank 3 has to be properly loaded.

Figure 5 shows the system for picking and loading blanks loading the blank to the head press of the stamping press line. This is performed using the loading robot 6. The loading robot 6 has picked up the blank as commented in previous figures and it is ready to load the blank, such that the blank is properly positioned relative to the desired position to be loaded to the head press of the stamping press line. In this way, the use of centering elements e.g. such as gravity tables or locating systems e.g. such as vision systems may be avoided. Furthermore, the blank may be loaded using a single robot.

It has to be noted that in figures 2-5 the separating robots and the loading robots are shown only very schematically. The structure, details and operating parameters of the separating robots and the loading robot are known by the person skilled in the art, who will be able to employ both types of robots with the most suitable features for any particular application. For example, the robots may be 4-axes, 5-axes or 6-axes, the layouts of the separating robots may be decided on the basis of the position of the wrist may adopt and/or the space available in each particular application.

Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and/or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow.