EP2607068A1 - Pressing assembly for reforming flat workpieces - Google Patents

Abstract

The arrangement (100) has a head press (110), downstream presses (120, 130, 140) and a line controller (105), where the head press is continuously operated in the context of shaping process of a planar workpieces, and the downstream presses are operated in single stroke. A pressing stroke of the head press is larger than a pressing stroke of the downstream presses. The head press and the downstream presses are synchronized with one another by the line controller, where lifting height of the downstream presses is less than 80% preferably 70% of lifting height of the head press. Independent claims are also included for the following: (1) a method for deforming a planar workpiece (2) a method for retrofitting a press arrangement.

Description

Technical area

The invention relates to a press arrangement for forming flat workpieces, comprising a head press and at least one downstream press and a line control. The invention further relates to a method for forming a flat workpiece.

State of the art

Press lines (tandem lines) for forming flat workpieces are known. They comprise a plurality of presses, which subject the workpieces one after the other to a processing step. In addition to the presses, an automated press line comprises a transport system for conveying the workpieces from the first press to the first subsequent press and further to all the presses arranged one behind the other. The presses and the transport system are controlled by a line control, e.g. B. a programmable logic controller (PLC) controlled and synchronized. Finally, a press line also includes means for feeding the workpieces into the first press and for discharging the machined workpieces from the last press.

Automated press lines are now operated either in continuous mode or in single stroke (intermitted mode). In the operating mode Single stroke ("Intermitted Mode"), the presses are stopped at top dead center (TDC) after each stroke and then restarted by the line control and thus also synchronized. In continuous mode ("continuous mode") all presses work in the Dauherhub, d. H. without stop in OT, and are electronically synchronized with each other.

In continuous operation, the performance (part output per minute) corresponds to the set press speed.

The single stroke allows compared to the endurance running a relatively simple synchronization of the individual presses via the line control. Because of the dwell time during which the rams are not moved, a time window for the removal and insertion of workpieces is created, the lifting height of the presses can also be kept low, which is advantageous in terms of price. Likewise, the presses have a high work capacity due to the higher speed of the flywheel at a given performance. However, due to the hold time in this mode, there is some reduction in throughput. If a predetermined performance is to be achieved, the presses of single-stroke press lines must work correspondingly faster than press lines in continuous operation. A press line in the single stroke, the 12 parts per Minute, for example, requires a ram speed, which corresponds approximately to that of an operated in continuous press line with a performance of 15 parts per minute.

The higher speed of the ram also has a negative effect on the drawing behavior of the material. In order to get an optimal forming, the speed should be as low as possible. High ram speeds and thus higher impact speeds also mean high wear of the pressing tool. Because the presses have to be stopped and restarted in each stroke in each stroke, the clutch and the brake are finally significantly more worn.

A press line, which is operated in continuous operation, thus allowing a lower ram speed. This is accompanied by a good forming result and less wear of the pressing tools, the clutches and the brakes. Also, there is an energy saving because the presses do not need to be restarted for each stroke. In contrast, there is the requirement of a greater lifting height, because the removal of the machined workpieces and the insertion of the next workpieces to be machined requires a certain amount of time - due to the continuous running of the presses - must be made available by a larger ram movement. However, a larger lifting height usually means substantially higher costs. The lower working capacity (due to the low rotational speed of the flywheel) must also be compensated either by increasing the engine power or increasing the flywheel again, which also has higher costs. Also, the synchronization of the presses of a continuously operated press line is more demanding, since no holding time can be used for it.

Presentation of the invention

The object of the invention is to provide a press assembly belonging to the technical field mentioned above, which avoids the disadvantages of the known press lines.

The solution of the problem is defined by the features of claim 1. According to the invention, in the context of the same forming process of one of the flat workpieces, the head press can be operated in continuous operation and the at least one downstream press can be operated in the single stroke.

This means that the first press (head press) can be operated at a lower ram speed due to the continuous run than the subsequent single-stroke downstream presses. Accordingly results in the head press a better forming result and a lower wear of the pressing tool, comparable to a (expensive) operated in continuous operation press line. In contrast to such a press line, however, the higher costs - in particular for the larger lifting height - only apply to the head press, not to the other presses which are operated in the single stroke.

Advantageously, only the first press is operated in continuous operation, with all downstream presses are operated in the single stroke.

Preferably, the head press and the at least one downstream press are synchronized with each other by the line control. This synchronization of the entire press line is simplified because the subsequent presses can be easily synchronized with each other due to the holding time.

Typically, the first processing step performed in the head press involves deep drawing with a relatively large stroke (eg, about 300 mm when machining vehicle body side panels). The following presses ("trimming presses") then exercise much smaller strokes. However, this also means that the increased ram speed during single stroke is critical, especially in the first processing step. Often the maximum speed of the entire press line operated in the single stroke is limited by the maximum possible deep drawing speed. With the aid of the solution according to the invention, the problem of too high a ram speed during deep drawing can be precisely avoided. The solution according to the invention is therefore particularly advantageous if a deep-drawing stroke of the head press is greater than a working stroke of the at least one downstream press, especially of all downstream presses. Because the deep drawing speed in the head press can be reduced with the aid of the solution according to the invention at the same throughput, a higher maximum speed of the press line results in the end.

Overall, the inventive press arrangement thus allows a good forming result with low wear of the pressing tool of the head press and - compared to a run in continuous operation press line - cheaper costs. Compared to a single-stroke press line, higher speeds are possible with the same forming quality.

Preferably, a ram speed of the head press at a height of 350 mm before a bottom dead center is less than 90%, preferably less than 80%, the speed of the at least one downstream press in the height of 350 mm before bottom dead center (UT). This is advantageous for all downstream presses. As mentioned, this allows an improved forming result in the head press, especially when the stroke used for forming is significantly greater than that in the subsequent presses. The height of 350 mm before UT is fundamentally arbitrary, but it should lie before the contact with the workpiece in the usual forming processes. The decisive factor is ultimately the impact velocity on the workpiece, which, however, depends on the dimensions and the position of the workpiece in the individual presses.

Advantageously, a lifting height of the at least one downstream press is less than 80%, preferably less than 70%, of a lifting height of the head press. This allows a more favorable design of the press arrangement and is made possible by the Einzelhubbetrieb and possibly by the lower forming stroke.

Preferably, a nominal force of the head press is at least twice as large as a nominal force of the at least one downstream press. This still allows flexible processing of various workpieces, as usually the required stroke and thus the required pressing forces in the head press are significantly greater than in the subsequent presses.

The inventive press arrangement is particularly suitable for operation with a transport system with robot kinematics. Robot kinematics are understood to mean a plurality of links connected by joints, wherein the joints (at least a majority of them) are motor-driven and thus enable a flexible movement of an object (eg a gripper) arranged at a free end of the kinematics. Compared with conventional solutions, eg. As dedicated systems with only linear axes, industrial robots are relatively easy and inexpensive and flexible use and therefore convertible. However, dedicated systems that are specifically adapted to the transport process often enable higher transport speeds and thus a higher perofrmance of the press line. With the aid of the inventive approach, a press line can be created that provides in the head press by the larger total stroke and in the downstream presses by the Einzelhubbetrieb sufficiently large time window for moving away and conveyance of workpieces by transport systems with robot kinematics. Overall, this results in a cost-effective yet powerful overall system.

Alternatively, the press arrangement according to the invention can also be operated with a transport system designed specifically for this purpose (with, for example, Cartesian kinematics).

With the aid of the inventive press arrangement can thus implement a method for forming a flat workpiece, the workpiece is first deep-drawn in a run in continuous running head press and then further processed in at least one downstream, operated in single stroke press, z. B. punched and / or further deformed.

If a flat workpiece is successively deformed in successive steps, the method according to the invention is particularly advantageous if a drawing depth on the head press is at least twice as great as a drawing depth on the at least one downstream press. In other advantageous applications of the invention, no further forming takes place in the downstream presses, but a different processing step, for. B. punching.

The invention also enables a quick and inexpensive conversion of an existing press arrangement with a single-stroke head press and at least one downstream press operated in the individual stroke. For this purpose, the existing head press is first replaced by an operable in continuous operation new head press, in particular with a larger stroke than the existing head press. In addition, the existing line control is newly configured so that the head press can be operated in continuous operation within the same forming process of a flat workpiece and the at least one downstream press can be operated in the individual stroke. If this is not possible, the existing line control will be replaced by a new control that enables this functionality.

From the following detailed description and the totality of the claims, further advantageous embodiments and feature combinations of the invention result.

Brief description of the drawings

Fig. 1

die zeitliche Abhängigkeit der Stösselposition in einer Presse im EinzelhubBetrieb;

Fig. 2

die zeitliche Abhängigkeit der Stösselposition in einer Presse im Dauerlauf;

Fig. 3

die Stösselgeschwindigkeit in Abhängigkeit der Stösselposition für eine Presse im Einzelhub-Betrieb und eine Presse im Dauerlauf;

Fig. 4

ein Blockdiagramm einer Ausführungsform einer erfindungsgemässen Pressenanordnung; und

Fig. 5

eine Seitenansicht der Ausführungsform.

The drawings used to explain the embodiment show:

Fig. 1

the time dependence of the ram position in a press in EinzelhubBetrieb;

Fig. 2

the time dependence of the ram position in a press in continuous operation;

Fig. 3

the ram speed as a function of the ram position for a press in Einzelhub-operation and a press in continuous operation;

Fig. 4

a block diagram of an embodiment of a press assembly according to the invention; and

Fig. 5

a side view of the embodiment.

Basically, the same parts are provided with the same reference numerals in the figures.

Ways to carry out the invention

In the FIG. 1 is the time dependence of the ram position in a press in Einzelhub mode shown. The x-axis 10 corresponds to the time, this being indicated in degrees (360 ° = one revolution of the press). The plunger is at 0 ° = 360 ° at top dead center and 180 ° at bottom dead center. The y-axis 20 denotes the height of the ram at a given time. How good of the FIG. 1 is recognizable, subsequent rounds are separated by a waiting time 30. In the example shown, 12 workpieces are processed per minute, but the tappet speed corresponds to 15 strokes per minute (SPM) due to the waiting time. The plunger thus moves for 4 s each and then stands still during the waiting time 30 1 s.

In the FIG. 2 the time dependence of the ram position is shown in a press in continuous operation, this press is also to work 12 pieces per minute. The x-axis 11 corresponds to the time, this being indicated in degrees (360 ° = one revolution of the press). The plunger is at 0 ° = 360 ° at top dead center and 180 ° at bottom dead center. The y-axis 21 denotes the height of the ram at a given time. One after the other follow each other without interruption, the plunger speed thus corresponds to the 12 SPM, one cycle takes 5 s. As can be seen from the slope of the curve shown, lower tappet speeds are required for the same stroke in continuous operation.

In the FIG. 3 the ram speed is shown as a function of the ram position for a press in single-stroke operation and a press in continuous operation. The x-axis 40 indicates the ram position in mm, where 0 mm corresponds to the bottom dead center (UT). The y-axis 50 indicates the ram speed in mm / s. The dashed curve 61 represents the ram speed as a function of the ram position for a single stroke operated press, the dotted-dashed curve 62 represents the ram speed in dependence of the ram position for a run in continuous operation press. As is apparent from the illustration, the operated in continuous operation a total stroke of 1'350 mm, the single-stroke operated press of 1'000 mm.

The workpiece is contacted and deformed in the area before bottom dead center (0 mm) by the pressing tool. As can be seen from the illustration, the speed of the plunger before contacting the workpiece, for. B. at a stroke of 350 mm in the single-stroke operated press (curve 61) significantly larger than in the continuous run press (curve 62).

The FIG. 4 shows a block diagram of an embodiment of a press assembly 100 according to the invention, the FIG. 5 shows a side view of the same.

The press assembly 100 comprises four presses, namely a head press 110 and three downstream presses 120, 130, 140. The presses 110, 120, 130, 140 are controlled by a line controller 105. Each of the presses 110, 120, 130, 140 comprises a press frame 111, 121, 131, 141, which stands in a foundation. At the upper end of the press frame 111, 121, 131, 141 is in each case an upper part 112, 122, 132, 142 with a drive and a vertically movable by the drive ram 113, 123, 133, 143 attached. The FIG. 5 shows the machine in a rest position, in which all rams are in the top dead center of each press.

At the entrance of the press arrangement 100, a receiving table 150, a washing station 160 and a centering station 170 are successively arranged in the processing direction. From the centering station 170, the workpiece to be machined is removed and conveyed into the head press 110. For this purpose, a conveyor 180 is used which has a tower 181 and a beam 182 pivotable thereon about a horizontal axis extending transversely to the processing direction. The beam 182 is telescopically designed so that a gripper 183 can be moved into the area of the preceding and the following station. The conveyor 180 is shown in detail in the WO 2005/051563 A1 (Güdel Group AG). Further such conveying devices 180 are arranged between the head press 110 and the first following press 120, between this and the other following presses 130, 140 and between the last following press 140 and an output table 190. Also, the conveyors 180 are controlled by the line controller 105.

The maximum stroke of the head press 110 is greater than the maximum stroke of the downstream presses 120, 130, 140. In combination with a corresponding line control, this allows operation in which the head press 110 in continuous operation and the downstream presses 120, 130, 140 in the single stroke operate: Head press 110 Press 120 Press 130 Press 140 Max. Stroke [mm] 1,350 1,000 1,000 1,000 mode jog single stroke single stroke single stroke eq. Speed [rpm] 12 15 15 15 Waiting time [s] 0 1 1 1 Pass [pcs / min] 12 12 12 12

The larger stroke of the head press 110 on the one hand enables the loading and unloading of the head press 110, in spite of the continuous operation, a sufficiently large time window for moving in the gripper of the conveyor is created. At the same time it is also ensured that in the head press 110 processing steps with a large stroke are feasible.

The first downstream press 120 is synchronized by the position of the head press 110, wherein substantially the passage of a predetermined angular position, for. B. a certain lead before top dead center, can be used as a trigger for a pressing operation of the first downstream press 120. The further presses 130, 140 are synchronized in a conventional manner on the basis of the release of the preceding press with a predetermined phase offset. The synchronization is advantageously realized so that a maximum deviation does not exceed ± 5 °.

An existing, in particular single stroke operated press line can be easily upgraded by the existing head press by a continuous operable new head press with enlarged stroke is replaced. Also, the controller is adapted so that the inventive combined continuous / Einzelhub operation is enabled.

The invention is not limited to the illustrated embodiment. The type and number of presses may differ from the example shown. The head press does not necessarily have a larger stroke than the downstream presses. Likewise, another conveyor system can be used, for. B. a conventional system with Cartesian kinematics or a different type of robot-based system.

In summary, it should be noted that a press arrangement is created by the invention, which avoids the disadvantages of the known press lines.

Claims (10)

Press arrangement for forming flat workpieces, comprising a head press and at least one downstream press and a line control, characterized in that in the same forming process of one of the flat workpieces the head press is operable in continuous operation and that the at least one downstream press is operable in the single stroke. Press arrangement according to claim 1, characterized in that a press stroke of the head press is greater than a press stroke of the at least one downstream press. Press arrangement according to claim 1 or 2, characterized in that the head press and the at least one downstream press are synchronized with each other by the line control. Press arrangement according to one of claims 1 to 3, characterized in that a ram speed of the head press at a height of 350 mm before a bottom dead center less than 90%, preferably less than 80%, the speed of at least one downstream press in the amount of 350 mm before bottom dead center. Press arrangement according to one of claims 1 to 4, characterized in that a lifting height of the at least one downstream press is less than 80%, preferably less than 70% of a lifting height of the head press. Press arrangement according to one of claims 1 to 5, characterized in that a nominal force of the head press is at least twice as large as a nominal force of the at least one downstream press. Press assembly according to one of claims 1 to 6, comprising a transport system for conveying the workpieces from the head press to the at least one downstream press, wherein the transport system comprises a robot kinematics. Method for forming a flat workpiece, wherein the workpiece is first deep-drawn in a head-operated in continuous operation and then further processed in at least one downstream, operated in the single stroke press. A method according to claim 8, characterized in that a drawing depth on the head press is at least twice as large as a drawing depth on the at least one downstream press. Method for converting a press arrangement with a single-stroke head press and at least one downstream press operated in the individual stroke, comprising the following steps: a) Replacing the existing head press by a running in continuous operation new head press, in particular with a larger stroke than the existing head press; and b) arranging and / or configuring a line control, by means of which in the same forming process of a flat workpiece, the head press is operable in continuous operation and the at least one downstream press is operated in the single stroke.

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