Methods and equipment for delivering sheet metal panels to punch presses.

Abstract

Page 1 of 1 Summary of the invention. The following steps are for aligning the sheet metal (1) in the correct position for The insertion into the punch press (2) is that the position is aligned in the feeding direction. It will be adjusted by the way of the bracing (6,7) alignment in the second direction perpendicular to the direction The feeding mechanism will be such that the position of the metal plate (1) in the second direction is taken into account. Determined by the sensor(17) and control unit(18) and the deviation of the metal plate from its position. The device receives a predetermined alignment in the second direction from the control unit. Consider further determination; the alignment in the second direction will be controlled by the path of the arrangement set. For the gripping mechanism which is provided for feeding the metal sheet to the punch press by... Control the arrangement for gripping in such a way that the deviation is compensated and the metal plate is obtained. Correct alignment.

Description

Method and apparatus for feeding a sheet metal panel to a stamping press Field of invention The invention relates to a method for aligning a sheet metal panel during the feeding of the sheet metal panel to a processing station, in particular to a stamping press, wherein the feeding to and into the processing station takes place in a first direction (Y axis) of two orthogonal directions (X axis and Y axis), wherein in a first alignment step the sheet metal panel is aligned in the first direction (Y axis) and in a second step the alignment in the second direction (X axis) in order to achieve a predetermined alignment position of the sheet metal panel, and wherein the sheet metal panel is gripped by a gripping arrangement for feeding and moved to the processing station and inserted into the processing station and stamped in the processing station to produce the desired processing image, in particular stamping image and preferably additionally moved back and forth in the second direction.Furthermore, the invention relates to a device for carrying out the method and a system for producing stamped parts with such a device. background In the metal packaging industry, lids for tin cans or deep-drawn parts are produced today. Canned goods – made of steel or aluminum, round or irregular – are mostly produced on high-performance machines. manufactured. For productivity reasons Portal presses are used, which allow the use of Multiple tools are possible. Depending on the press type and available pressing force, tools are used in a "zigzag" or linear arrangement. With each With each press stroke, several components are manufactured simultaneously. The base material – aluminum or steel – is processed in the press in the form of sheet metal. Using one or more gripper systems or rollers, the sheet metal is fed to the tool and then processed step by step. Depending on the tool and In this feed system, the sheets are moved in an orthogonal coordinate system only in the Y direction or in both the X and Y directions. Again, for productivity reasons, sheets that are as large as possible are processed. The larger the sheets, the fewer sheets need to be painted, cut, fed, etc. In any case, however, the sheet metal sheets must be positioned with high precision at each punching position. The sheet metal panels are fed into the system in the form of a stack. A single stack can contain several thousand sheets. Typically The weight limits the height of the stack. The stacks are placed on chain or roller conveyors and then either moved in the direction of production. Sheet metal processing in the press or at 90° to the production direction into the stacking position Promoted. An electrically or hydraulically driven lifting system raises the stack to a vertical position. Position in which the sheet metal panels are individually gripped and fed towards the plate press. Due to the great weight of the stacks (usually several tons), the stacks can only be moved to the destacking position with relative imprecision. The stacking position can therefore vary from stack to stack by up to several centimeters. Furthermore, the stacks often exhibit stacking defects. The sheets may have shifted either during the stacking process in the coil cutting line or in the painting line, or during transport to the The processing plant may have shifted (fanned out). Modern stacking systems must now be able to compensate for such errors. More precise centering of the Stacking would require a complex and expensive mechanism. Furthermore, unstacking is an experience everyone has. Individual sheets are also handled relatively inaccurately using suction grippers. When the sheet is gripped and fed towards the sheet press, it is at most oiled. Rollers are typically used for this process, which can cause additional inaccuracies in the lateral positioning of the sheet. Before a sheet fed into the stamping press can be processed in the die, it must be brought into a precisely defined position using an alignment device. This applies both in the direction of feed to the stamping press and in the perpendicular direction to it. The accuracy must be within + / - 0.2 mm. One reason for this is that the The various punching positions in the sheet metal should be as close together as possible to achieve maximum material utilization. Additional reasons may include the fact that the sheets are lithographed (printed) and the punching must precisely match the print, or that the remaining web width at the sheet edge should be kept very small. This is particularly important when processing... The use of sheet metal presses with multiple tools is an important criterion for achieving high productivity. Figure 1 shows mutually perpendicular X and Y axes, which are used to describe the feeding of the respective sheet metal panel to the stamping press and the The centering of the sheet metal panel can be used both for explaining the prior art and for explaining the invention. The destacker 2 and the press 20 are also shown schematically in Figure 1. The centering of the sheet metal panels in the X and Y directions is carried out according to the prior art, for example, as shown schematically with reference to Figures 2 to 6. The alignment of a sheet metal panel destacked from the stack of sheets Sheet metal is placed on a centering table 15, which The figure has conveyor belts 3, 4 and 5. Figure 3 shows that a sheet metal sheet 1, which has been stacked from the stack of sheet metal sheets (not shown) by the destacker 2, is placed on the The sheet metal panel has been placed on the centering table. The sheet metal panel is pushed along the centering table 15 in the positive Y direction (Y+ direction) by means of the conveyor belts 3, 4, and 5. This direction is defined as the direction towards the press 20. Figure 4 shows the panel 1 in a position where it has been advanced in the Y+ direction until it rests only on the conveyor belt 5. This is the reversal position from which the panel 1 is moved by the conveyor belt 5 in the negative Y direction (Y-) for centering and alignment, i.e., moved a short distance back towards the stacker 2. Figure 5 shows how, after being pushed in the Y direction by the conveyor belt 5, the sheet metal panel 1 rests against two stops 6 and 7, which have been raised above the table surface for this purpose. Thus, the panel is centered and aligned along the Y axis. Afterward, a Stop 8 in the X+ direction until close to the board The sheet is positioned, and finally a slider or further stop 9 pushes the sheet in the negative X direction (X-) against the stop 8, so that the centered or aligned position of the sheet metal sheet 1 is achieved as shown in Figure 6. The alignment in the X and Y directions can be adjusted in another embodiment according to the prior art. be combined, e.g. by using a spring-loaded mechanism The vacuum gripper system pushes the panel against a stop X+ and Y-. DE 43 45 184 AI shows a centering device in which a centering device for sheet metal panels, designated as an alignment station, is designed with two lateral stops and a rear stop for the sheet metal panel. Once a sheet metal panel has its definitive Once orientation and position have been achieved or aligned, this is taken over by a handling system and for processing in tool 20. Figure 6 shows a gripper 11 which grasps the sheet 1 in its previously centered / aligned position at its rear end and feeds it towards the press 20 in direction Y+. The gripper, which holds the sheet in Y+ The gripper that advances the tool and, if necessary, moves it in the X- and X+ directions to create the desired die-cut pattern can be the same gripper that gripped the centered panel 1 in the position shown in Figure 6. It is known that a second gripper is present, which moves the sheet 1 in front of press 20 away from the first gripper. has taken over. The explained alignment or State-of-the-art centering mechanisms are complex and require maintenance. Furthermore, these mechanisms need some time to align the board. During the The centering or alignment process must not The handling system, or rather the gripper, is not yet allowed to take over the sheet metal panel. This is partly because the alignment is not yet complete and partly because the Alignment mechanism causes a collision with the gripper could cause. Description of the invention The object of the invention is to create an improved method for aligning a sheet metal panel during its feeding to a processing station. In particular, the method should enable reduced maintenance requirements and faster feeding to the press. This task is solved in the aforementioned method by aligning the sheet metal panel in the second direction (X-axis) through the following steps: - Determination of the position of the sheet metal panel in the second direction (X axis) by at least one sensor; - Detection of the deviation of the sheet metal panel from its predetermined alignment position in the second direction by evaluating the sensor signal with a control unit; and - Correction of the deviation of the alignment position from the predetermined alignment position in the second direction (X axis) after gripping the sheet metal panel by means of the gripping arrangement, by the gripping arrangement being controlled by the control device, which moves the sheet metal panel into the predetermined alignment position in the second direction during the feeding movement of the sheet metal panel to the processing station. The invention thus aims to eliminate the separate alignment step of moving the sheet metal panel in the X-axis, or in the second direction. Instead, the position of the panel in the X-axis is detected by at least one sensor, preferably without contact, so that this position is recognizable in a control unit connected to the sensor. Thus, instead of first moving the panel to a defined X-position and then moving the panel to the To transfer the gripping arrangement, initially only the X The position of the sheet metal panel is detected. Based on the received values, the control system calculates the transfer position for the gripping arrangement, and the gripping arrangement brings the sheet metal panel into the correct position with respect to the X-axis when feeding it to the processing station. compensates for the sensor device and the The control unit detected a deviation from the predetermined alignment position in the second direction. Therefore, no alignment components need to be adjusted or maintained for alignment in the X-axis. The advantage of this approach is therefore, on the one hand, the elimination of the complex and maintenance-intensive Alignment mechanism. Furthermore, the time required by this mechanism to align the board is eliminated. Preferably, before gripping the sheet, the position of the gripping arrangement is adjusted to the sheet's deviation in the X direction by shifting the gripping arrangement accordingly. This ensures that the sheet is gripped at the designated point on the sheet metal. Preferably, the position in the second direction is determined by a stationary sensor, resulting in a simple and robust design. Alternatively or additionally, the position in the second direction can be determined by a movable sensor, in particular by arranging a sensor on the gripping assembly and moving it across the sheet metal panel. This allows the use of a movable sensor, which can simplify the sensor's design without requiring additional mechanics for its movement. A line sensor with or without a reflector, or a camera with image processing, can be used as the sensor for the sensing device. The sensor can be positioned above or below the sheet metal position, or it can be a sensor located both above and below the sheet metal position. Multiple sensors in all the described variants can improve position detection, especially when optical sensors are used, since the sheet metal can have different reflective properties depending on the material and pretreatment. However, contact-based sensing devices can also be used instead of non-contact optical sensing devices. The invention further aims to provide an improved device for aligning a sheet metal panel during its feeding to a processing station, in particular a stamping press. to create. In particular, the device is intended to enable lower maintenance requirements and faster feeding to the processing station or press. This problem is solved with a device having the features of claim 10. The object of the invention is therefore, also in the device, to avoid the sheet metal panel displacement in the X-axis or the second direction as a separate alignment and instead to make the position of the panel in the X-axis detectable by at least one sensor, so that this position is recognizable in a control unit connected to the sensor. Instead of first bringing the panel into a defined X-position and then transferring the panel to the gripping arrangement, the device initially allows only the X-position of the sheet metal panel to be detected. Based on the values ​​obtained, the control unit calculates the Takeover position for the gripping arrangement and the The gripping arrangement brings the sheet metal panel into the correct position during feeding to the processing station. regarding the X-axis. Therefore, no Alignment components for alignment in the X-axis of the device are adjusted and maintained. The advantage of this device is therefore on the one hand, the elimination of the costly and The alignment mechanism, which requires maintenance, is eliminated. Furthermore, the time this mechanism needs to align the board is no longer required. Preferably, a stationary sensor is provided to determine the position in the second direction, resulting in a particularly robust and maintenance-free device. However, it is also possible to provide a movable sensor of the sensor element to determine the position in the second direction, in particular that the sensor of the sensor element is arranged on the gripping arrangement and movable across the sheet metal panel by it, which has the advantage of allowing for more precise control of the sensor's movement. no additional mechanics are needed, as the gripping arrangement is already designed to perform the required movement. In particular, a line sensor with or without a reflector can be used as the sensor, or a camera with image processing can be used as the sensor. Furthermore, the sensor system can include sensors positioned above or below the sheet metal position. These measures, or rather, the types and arrangements of sensors mentioned above, can improve the detection of the sheet metal edge in industrial environments. Therefore, it can be particularly advantageous to use sensor systems with several different sensors to detect the sheet metal position. Furthermore, the invention has the task of The aim was to create an improved plant for the production of stamped parts from sheet metal. This problem is solved with a system according to claim 18. In all embodiments of the invention, when feeding a sheet metal panel to a stamping press, the panel is aligned into the correct position for insertion into the press by adjusting the alignment position in the feed direction using stops. Alignment in the second direction, orthogonal to the feed direction, is achieved by determining the position of the sheet metal panel in this second direction using at least one sensor and a control unit. The control unit then determines the deviation of the sheet metal panel from the predetermined alignment position in this second direction. Finally, alignment in the second direction is performed by means of the gripping arrangement provided for feeding the sheet metal panel to the stamping press. The gripping arrangement is controlled in such a way that the deviation is compensated for and the sheet metal panel is correctly aligned. Brief description of the drawings Further elaborations, advantages, and applications of the invention will become apparent from the dependent claims and from the following description with reference to the figures. These will show: Figure 1 schematically shows a stacker and a stamping press as well as a coordinate system to illustrate the feeding of a sheet metal panel from the stacker to the stamping press both in the prior art and in a procedure according to the invention; Figures 2 to 6 represent a state-of-the-art procedure; Figures 7 to 11 show a procedure and a device according to an embodiment of the invention; and Figure 12 shows an example of a gripper in the gripping arrangement. Way(s) to implement the invention For the explanation of an embodiment of the invention, reference is also made to the coordinate system according to Figure 1. The prior art has been previously explained with reference to Figures 2 to 6, to which reference may be made here. Figure 7 shows a centering table 15 of an embodiment of the invention, in which a sensor means 16 with at least one sensor and optional illumination means and / or reflectors is provided, which sensor means can detect the position of the edge of a sheet metal panel, which is placed on the table within the detection range of the sensor means, in the X-coordinate, as will be explained later. Thus, together with a control device 18, which receives the signal from the sensor means 16, the position of the sheet metal panel in the X-coordinate can be detected, or the deviation of the sheet metal panel 1 from the desired predetermined alignment position in the X-coordinate. In Figure 7, as well as in Figures 8 and 9, the gripping arrangement is not shown to simplify the figures. However, a gripping arrangement is present and will be explained later with reference to Figures 10, 11, and 12. Figure 7 also shows conveyor belts 3, 4, and 5, by means of which the respective sheet metal panel 1 can be moved back and forth on the centering table in the Y-coordinate direction. Instead of or in addition to conveyor belts, other means for this movement can also be provided, for example, rollers partially recessed in the table. The table 15 can be equipped in a known manner with means that facilitate the movement of sheet metal panels on the table, for example, with regularly arranged rolling elements or with means for generating air cushions. This is known to those skilled in the art and will not be explained further here. Figure 8 shows a sheet metal panel 1, which has been placed on the centering table and initially on the conveyor belts 3 and 4. The sheet metal panel is aligned in the Y direction by means of the conveyor belts 3, 4, and 5, by first advancing the sheet metal panel 1 in the Y+ direction. Once the sheet metal panel has reached a position where it rests only on the conveyor belt 5, as shown in Figure 9, it is pushed in the Y- (Y-minus) direction against two stops 6 and 7, as already explained in the prior art and illustrated here in Figure 10. This is the preferred method of alignment in the Y direction. Other known methods of alignment in the Y direction can also be used. In the figures of the exemplary embodiment, the sensor means 16 comprises at least one stationary sensor 17 with a longitudinal extent in the X coordinate direction. This sensor is, for example, a line sensor that has a plurality of light-sensitive sensor elements arranged in series and thus constitutes a The sensor can emit a signal that determines the position of an object above it by identifying which sensor elements are obscured by the object and which are not. In this example, such a sensor is arranged in a recess 13 of the tabletop such that it lies below the metal plate 1. Furthermore, it is arranged so that, with the metal plate 1 aligned in the Y-coordinate, it can emit the position of the edge 1' above the sensor in the X-coordinate as a sensor signal. Figure 10 shows that the edge 1' of the metal plate 1 lies above the sensor, so that part 17' of the sensor is covered by the metal plate 1. The part of the sensor element located in the X+ direction, which is not covered by the metal plate 1, is labeled 17''.The sensor is connected to a control unit 18, which evaluates the sensor signal and can thus calculate the deviation of the position of the sheet metal panel 1 in the X-coordinate from the desired orientation position of the sheet metal panel. This control unit also controls the drive of the gripper 11 of the gripping arrangement. The detection of the exact position of the sheet metal panel by the sensor means can be carried out using only one sensor, e.g., with the aforementioned line sensor, and can be implemented with or without a light source and / or reflector, or the sensor means can comprise several sensors whose signals are evaluated in the control unit. The sensor means can also include an optical system, such as a camera with image processing, which is used in addition to or instead of a sensor.The sensors or cameras of the sensor device can be positioned above the sheet metal position and / or, as shown in the example, below the sheet metal position. For accuracy reasons, multiple detection points can also be provided. The sheet metal position can be detected at one edge or the other of the sheet metal, or, in the case of scrolled sheets that have two edges on each side, at the edges of the sheet metal. The scanning can be done on both edges of one side, or on both edges of one side, or on both sides. The sensor system can include, instead of or in addition to at least one stationary sensor, the detection of the sheet metal edge using at least one movable sensor. For example, one sensor of the sensor system can be arranged on the gripper 11, and to determine the position of the sheet metal, the control unit moves the gripper 11 over the sheet metal in such a way that its position in the X-coordinate is determined. Since the control unit knows the position of the gripper of the gripping arrangement, it can also derive the position of the sheet metal from the sensor signal in this case. In this case, a line sensor can be omitted, and a simpler sensor can be used. The sensor device may also include a sensor that is movable separately from the gripper. For example, a movable proximity switch. can be provided for. In this case, the detection of the sheet metal edge can be carried out using a timing method. Since the initial position of the sensor is known and the If the sensor's movement speed is known, the time at which the sensor... The sheet metal edge is detected. A precise position can be derived from this time. However, maintenance-free operation is preferred for the aforementioned reason. Sensor devices that work with a stationary sensor or camera, or with a gripper arranged movable sensor or with a camera arranged on the gripper. By determining the position of the sheet metal panel in the second direction (X axis) using the sensor means 16 and detecting the deviation of the sheet metal panel from its predetermined alignment position in the second direction By evaluating the sensor signal with the control unit, the deviation can subsequently be corrected during the feeding or transport of the sheet metal to the press. Figure 10 shows that the sensor 17 of the sensor element and the control unit 18 have detected a deviation ΔΧ of the position of the sheet metal in the X-coordinate from the desired orientation or centering. This deviation is then corrected by the gripping arrangement. The correction of the deviation of the alignment position from the predetermined alignment position in the second direction (X-axis) is carried out after the sheet metal panel has been gripped by the gripping arrangement. This is achieved by the gripping arrangement, controlled by the control unit, moving the sheet metal panel into the predetermined alignment position in the second direction during its feed movement to the processing station. This can be accomplished by the gripping arrangement, with gripper 11, which is movable in the X and Y directions by means of corresponding gripper drives as known by the control unit, first performing a movement in the X- (Xminus) direction to correct the amount ΔΧ, and then performing the movement towards the press 20 in the Y+ direction. Preferably, however, a combined X and Y movement of the gripper 11 is used, such that it is moved in the direction of arrow K, with the movement in the X- (Xminus) direction only occurring until the deviation ΔΧ is eliminated. Preferably, before gripping the board, the position of the gripping arrangement is adjusted to the detected, differing position of the board in the second direction by shifting the gripping arrangement accordingly in the second direction to grip the board at the intended location. This is illustrated in Figure 10, where the gripper 11 of the gripping arrangement has also been shifted substantially by the amount ΔΧ in the second direction before gripping, in order to grip the board 1 at the intended location. The gripper 11 then places the sheet metal panel into the press 20 and performs the known punching motion in the X and Y directions, as shown in Figure 11. The gripping arrangement can also have two grippers in a known manner, between which the sheet metal panel 1, aligned by the first gripper, is transferred. The gripper 11 of Figure 10 then performs the corrective movement in the X (X-) direction and the Y movement towards the punching press, performing all punches of at least one row of the punching pattern (usually two or three punching rows), after which a second gripper... The gripper assembly takes over the sheet metal panel and completes the punching process, while the first gripper is moved back to take over the next sheet metal panel. Figure 12 shows a well-known grabber of the The gripping arrangement is as already used in conventional devices and as is also used in the present invention. The gripper 11 is movable in the X and Y directions by corresponding drives, which are controlled by the control unit. The gripper has two jaws 19 by means of which the sheet metal panel can be gripped at its rear edge (viewed in the Y+ direction) and also released again. This is known and will not be explained further here. While preferred embodiments of the invention are described in the present application, it should be clearly pointed out that the invention is not limited to these and can also be carried out in other ways within the scope of the following claims.