Bending press with active crowning system and bending method with active crowning system

Abstract

A bending press (12) with active crowning system comprises an upper beam (14) and a lower beam (16). The lower beam (16) is provided with at least one crowning cylinder (18, 20, 22) connected to a pressurized oil feeding apparatus (24). The bending press further comprises at least one position or deformation transducer (26) arranged on the upper beam (14), at least one position or deformation transducer (28) arranged on the lower beam (16), and a central control unit (30) to which the position or deformation transducers (26, 28) and the oil feeding apparatus (24) are operatively connected. The pressurized oil feeding apparatus (24) is driven by a variable speed pump motor (32), based on the position or deformation measured at the at least one position or deformation transducer (26) arranged on the upper beam (14), and at least one position or deformation transducer (28) arranged on the lower beam (16).

Description

FIELD OF APPLICATION

[0001] The present invention relates to a bending press with active crowning system and to a bending method with active crowning system.PRIOR ART

[0002] As is known, sheet bending presses comprise a movable upper beam and a fixed lower beam, wherein the upper beam moves substantially in a vertical direction approaching and receding from the lower beam.

[0003] The lower beam, by means of the use of special tools, acts as a die, whilst the upper beam, which is also provided with special tools, acts as a punch. The die and punch cooperate to irreversibly deform a sheet that is inserted therebetween, by means of the movement of the upper beam approaching the lower beam.

[0004] This type of press is equipped with crowning systems for the lower beam, which make it possible to compensate, at least partially, for deformation whereto the beams are subjected during crowning, especially in the case of very long beams.

[0005] A first example of such crowning systems is given by jacks arranged inside the lower beam, supplied by a large-capacity pump, by means of a proportional valve. In this case it is necessary to manage large quantities of oil, which is subsequently discharged from the plant, resulting in an obvious waste of energy and resources.

[0006] Also known is a second system, described in the patent EP2682198, in the name of the same applicant, wherein an accumulator is used that is charged by a pump and which feeds jacks by means of a proportional valve.

[0007] The prior art, whilst widely used and appreciated, is not without drawbacks.

[0008] Firstly, in the systems of the prior art, it is necessary to maintain the crowning system operational also when the use thereof is not required, so that it is ready when necessary.

[0009] Secondly, the systems of the prior art comprise elements such as, for example, valves and solenoid valves that dissipate some of the energy stored and made available for crowning.

[0010] Furthermore, the presence of dissipative elements leads to heating of the oil and a loss in the performance of the same thereby effectively shortening the useful life thereof.DISCLOSURE OF THE INVENTION

[0011] The need is thus felt to solve the drawbacks and limitations mentioned in reference to the prior art.

[0012] The need is therefore felt to provide a bending press with an active crowning system that is not operational when not required.

[0013] There is also a need to provide a bending press with an active crowning system that is devoid of dissipating elements or else with a limited number thereof.

[0014] There is also a need to provide a bending press with an active crowning system that, in order to lengthen the useful life thereof, makes it possible to limit the heating of the oil.

[0015] Such requirements are met at least in part by a bending press with an active crowning system according to claim 1 and by a bending method with an active crowning system according to claim 6.DESCRIPTION OF THE DRAWINGS

[0016] Further features and advantages of the invention will become more apparent from the following detailed description of preferred, non-limiting embodiments thereof, wherein: Figure 1 shows, in schematic form, a side view of a bending press according to one possible embodiment; Figure 2 shows, in schematic form, a bending press with an active crowning system according to one possible embodiment; Figure 3 shows, in schematic form, a bending press with an active crowning system according to one possible embodiment; and Figure 4 shows, in schematic form, a portion of a bending press with a with an active crowning system according to one possible embodiment; Elements or parts of elements that are common to the embodiments described hereinafter will be indicated using the same numerical references.DETAILED DESCRIPTION

[0017] In Figure 1, a bending press with active crowning system according to the present invention is shown in schematic form using the general reference numeral 12.

[0018] The bending press 12 comprises an upper beam 14 and a lower beam 16, wherein the lower beam 16 is provided with at least one crowning cylinder 18, 20, 22 connected to a pressurized oil feeding apparatus 24.

[0019] Furthermore, the bending press comprises at least one position or deformation transducer 26 position on the upper beam 14, at least one position or deformation transducer 28 positioned on the lower beam 16, and a central control unit 30 to which the position or deformation transducers 26, 28 and the pressurized oil feeding apparatus 24 are operatively connected.

[0020] The oil feeding apparatus 24 is driven by a variable speed pump motor 32 connected to the central control unit 30, based on the position or deformation measured by the at least one position transducer 26 positioned on the upper beam 14, and by the at least one position or deformation transducer 28 positioned on the lower beam 16.

[0021] The variable speed pump motor 32 thus constitutes the power unit of the apparatus.

[0022] The pump motor 32 may comprise a servomotor and a pump with a fixed displacement or with a variable displacement.

[0023] The servomotor of the pump motor 32 adjusts, in real time, the direction of rotation thereof and the angular velocity thereof, thereby allowing the pump (with a fixed displacement or possibly with a variable displacement) to process the oil flow rate necessary in order to modify the deformation of the lower beam according to the processing on the part of the control unit.

[0024] According to a possible embodiment, the position or deformation transducers 26, 28 may be position transducers.

[0025] According to a possible alternative embodiment, the position or deformation transducers 26, 28 may be deformation transducers, and in particular strain gauges.

[0026] As shown for example in Figure 3, the pressurized oil feeding apparatus 24 may comprise a pressure transducer 34 that is adapted to detect the crowning pressure and that is operatively connected to the central control unit 30.

[0027] According to one possible embodiment, the central control unit 30 may comprise a press control unit 36 and a pump motor control unit 38. The two units 36, 38 may be separated therebetween, and, for example, the press control unit may be arranged on board the press, and the pump motor control unit 38 may be arranged on board a separate unit intended to group together those devices that relate to the pump motor, as will be described below.

[0028] According to one possible embodiment, the feeding apparatus comprises a safety unit 40 having the function of safeguarding the system from abnormal overpressures and / or depressions, safeguarding for operators, and / or flushing for the pump of the pump motor 32.

[0029] As may be seen in Figure 3, the safety unit 40 may derive from the main hydraulic power transmission line. Such safety unit is necessary in order to comply with those essential safety requirements that are envisaged by legislation.

[0030] As may be seen in Figure 4, the feeding apparatus 24 may be arranged on a carriage 42.

[0031] The carriage 42 may have a structure known per se, comprising for example wheels 422, and a handle 424.

[0032] According to one possible embodiment, the carriage 42 may be utilized by several presses and may therefore be of the transportable type. In this case, according to one possible embodiment, the pump motor 32, the safety unit 40 and the pump motor control unit may be arranged on the carriage 42.

[0033] A method for bending a sheet with an active crowning system will now be described in detail, using a press according to that just described.

[0034] In the essential form thereof, the method for bending a sheet using an active crowning system comprises the steps of: (a) arranging a bending press with active crowning system according to that just described; (b) approaching the upper beam 14 to the sheet and resetting the lower beam 16; (c) tracking the deformation of the upper beam 14 by the lower beam 16 and crowning in position; (d) reaching the bending height by the upper beam 14; (e) resetting the lower beam 16; and (f) deactivating the feeding apparatus 24; wherein the step (c) of tracking the deformation of the upper beam 14 by the lower beam 16 and crowning in position is carried out by the pump motor 32 controlled by the central control unit 30 based on the measurements carried out by said at least one position transducer 26 arranged on the upper beam 14 and by at least one position transducer 28 arranged on the lower beam 16.

[0035] According to one possible embodiment, the pressurized oil feeding apparatus 24 comprises a pressure transducer 34 adapted to detect the crowning pressure, operatively connected to the central control unit 30, wherein the central control unit 30 carries out a feedback control of the crowning pressure by means of the pressure transducer 34 and / or monitoring the crowning pressure.

[0036] According to one possible embodiment, between step (a) and step (b) a washing step of the pump portion of the pump motor 32 may be envisaged.

[0037] At this stage the motor that starts the pump rotating turns on. The pump begins to circulate the oil therein. The valves of the safety group 40 allow the oil to return to a tank 402: renewal of the oil of the system is in this way permitted, which would otherwise always remain unchanged and would degrade, thereby leading to premature wearing of the pump.

[0038] Shortly before the impact of the punch arranged on the upper beam 14 above the sheet, the valves of the safety group 40 close the free passage to the tank 402 and thus the crowning cylinders 18, 20, 22 line is thereby activated. At the same time, the motor of the pump motor resumes the rotation and allows the pump to deliver the necessary and sufficient flow rate for the lower beam 16 to reset its position (straightening of the frame) .

[0039] According to one aspect of the present invention, the reset signal is sent by the position transducer 28 to the control unit 30 in the same way that the pressure of the plant may be sent by the pressure transducer 34.

[0040] Advantageously, these signals allow the central control unit 30 to manage the power (torque and revolutions) transmitted to the pump.

[0041] At this point, according to one aspect of the present invention, the upper beam 14 approaches the lower beam 16 in order to allow the punch to reach the necessary height in order to achieve the angle envisaged and set on the central control unit 30.

[0042] During the bending of the sheet, both beams 14, 16 undergo deformation: the central control unit 30 (and in particular the press control unit 36) compares the signal sent by the position transducer 26, which is integral to the upper beam 14, with the signal sent by the position transducer 28, which is integral to the lower beam 16, and possibly by the pressure transducer 34, and drives the motor of the pump motor 32 by means of actuation (in particular the pump motor control unit 38) so that the pump instantaneously and dynamically processes the flow rate necessary in order to reach the deformation values of the beams 14, 16.

[0043] Advantageously, the motor of the pump motor 32 may accelerate, decelerate, stop and / or reverse the motion thereof according to the requirements of the bending process.

[0044] Once the desired bending angle of the sheet has been reached (wherein the deformation values of the two beams 14, 16 are substantially equal), the relaxation step begins wherein the structure of the machine returns to the state without bending induced stresses. The working area of the upper beam 14 naturally returns to a flat state, whilst the crowning system actively depressurizes the line of crowning cylinders 18, 20, 22, sending the instantaneous pressure of the plant by means of the signal of the pressure transducer 34 to the central control unit 30.

[0045] In a final step, the upper beam 14 ascends back to the resting position thereof.

[0046] Thus, the advantages that may be achieved by the press and using the method according to the present invention are obvious.

[0047] Firstly a press has been provided that allows for the use of the crowning system, only when necessary for processing: the power unit (motor-pump) is activated only for that period of time that is necessary and sufficient for processing.

[0048] Moreover, with the exception of the valves within the safety unit, there are no in-line dissipative elements such as on / off, proportional direction and / or pressure solenoid valves.

[0049] Furthermore, the supply of power as required, together with the absence of dissipative elements, makes it possible to reduce the amount of installed power for the crowning system, less oil heating, and a limited loss of performance of the same, thereby effectively lengthening the useful life thereof.

[0050] The system may furthermore be applied to bending presses of any force and of any length.

[0051] The technology used allows for a reduction of the components installed: by supplying the power unit (motor-pump) with the required power, no valves are required for the distribution of oil.

[0052] The technology used furthermore eliminates the need for the accumulation of fluid energy by means of accumulators in order to make power immediately available: the power unit (motor-pump) is capable of transmitting power instantaneously, similarly to energy storage systems.

[0053] A person skilled in the art will be able to make modifications to the embodiments described above and / or substitute described elements with equivalent elements, in order to satisfy particular requirements, without departing from the scope of the accompanying claims.

Claims

1. Bending press (12) with active crowning system comprising an upper beam (14) and a lower beam (16); said lower beam (16) being arranged with at least one crowning cylinder (18, 20, 22) connected to a pressurized oil feeding apparatus (24); said bending press further comprising at least one position or deformation transducer (26) positioned on said upper beam (14), at least one position or deformation transducer (28) positioned on said lower beam (16), and a central control unit (30) to which said position or deformation transducers (26, 28) and said pressurized oil feeding apparatus (24) are operatively connected; characterized in that said pressurized oil feeding apparatus (24) is driven by a variable speed pump motor (32) connected to said central control unit (30), based on the position or deformation measured by said at least one position or deformation transducer (26) positioned on said upper beam (14), and by said at least one position or deformation transducer (28) positioned on said lower beam (16).

2. Bending press (12) according to the preceding claim, characterized in that said pressurized oil feeding apparatus (24) comprises a pressure transducer (34) adapted to detect the crowning pressure, operatively connected to said central control unit (30).

3. Bending press (12) according to any one of the preceding claims, characterized in that said central control unit (30) comprises a press control unit (36) and a pump motor control unit (38).

4. Bending press (12) according to any one of the preceding claims, characterized in that said feeding apparatus comprises a safety unit (40), having the function of safeguarding the system from abnormal overpressures and / or depressions, safeguarding for operators, and / or flushing for the pump of the pump motor (32).

5. Bending press (12) according to any one of the preceding claims, characterized in that said feeding apparatus (24) is arranged on a carriage (42).

6. Bending process of a sheet with active crowning system comprising the steps of: (a) arranging a bending press with active crowning system according to any one of the preceding claims; (b) approaching the upper beam (14) to the sheet and resetting the lower beam (16); (c) tracking the deformation of the upper beam (14) by the lower beam (16) and crowning in position; (d) reaching the bending height by the upper beam (14); (e) resetting the lower beam (16); and (f) deactivating the feeding apparatus (24); characterized in that said step (c) of tracking the deformation of the upper beam (14) by the lower beam (16) and crowning in position is carried out by the pump motor (32) controlled by the central control unit (30) based on the measurements carried out by said at least one position or deformation transducer (26) arranged on said upper beam (14) and by said at least one position or deformation transducer (28) arranged on said lower beam (16).

7. Process according to the preceding claim, characterized in that said pressurized oil feeding apparatus (24) comprises a pressure transducer (34) adapted to detect the crowning pressure, operatively connected to said central control unit (30), said central control unit (30) carrying out a feedback control of the crowning pressure by means of said pressure transducer (34) and / or monitoring the crowning pressure.

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