ITTV20120125A1 - DEVICE FOR BENDING IN FOLDING PRESSES. - Google Patents

Description

T ITOLO: DEVICE FOR BENDING IN BENDING PRESSES

DESCRIPTION

object

press brakes.

Nowadays in bending presses, comprising an upper crosspiece and a lower crosspiece, it is known to use a crowning circuit, comprising a large flow pump, in which the deformation of the jacks is controlled by a proportional pressure which operates this control by acting on the circuit pressure.

To do this, due to the way a valve of this type is made, large quantities of oil must be drained and therefore large amounts of energy are unnecessarily wasted.

There are therefore high management costs, also given that the time required to carry out the processing cycle is increased and therefore productivity decreases.

The main aim of what forms the subject of the present invention is therefore that of solving the technical problems highlighted, eliminating the drawbacks of the cited known art and therefore devising an invention that allows to achieve greater energy savings.

Within the scope of the above aim, another important object of the invention is to provide a device which allows the press to be activated in a very short time by delivering, in a set pressure range, large instantaneous flows of oil.

Another object of the invention is to allow to use only the necessary quantity of oil, avoiding to discharge the excess under pressure unnecessarily.

Another object of the invention is to allow to have a lower installed power.

Another object of the invention is to allow to achieve a higher reaction speed of the crowning, reducing the cycle time and increasing productivity.

Not least object is to obtain a device which is structurally simple, which has low manufacturing costs and can be manufactured with the usual known systems.

The aforementioned task and purposes, as well as others which will appear more clearly later, are achieved by a device for the active crowning of bending presses comprising an upper crosspiece and a lower crosspiece, which is characterized by the fact that it comprises a pump suitable for charging at least one accumulator, said accumulator being adapted to control said lower crosspiece by means of a proportional direction valve.

Further characteristics and advantages of the invention will become clearer from the detailed description of a particular, but not exclusive, embodiment, illustrated by way of non-limiting example in the attached drawings, in which:

fig. 1 shows a hydraulic diagram of a bending press comprising an accumulator with a flow rate of less than one liter;

fig. 2 shows a hydraulic diagram of a bending press comprising an accumulator with a flow rate greater than one liter;

fig. 3 illustrates a flow chart.

In the following embodiments, single characteristics, reported in relation to specific examples, can actually be interchanged with other different characteristics, existing in other embodiments.

Furthermore, it should be noted that everything that in the course of the procedure for obtaining the patent turns out to be already known, is intended not to be claimed and subject to excerpt (disclaimer) from the claims.

With reference to the aforementioned figures, the number (1) indicates a device for the active crowning of bending presses comprising an upper cross member (2) and a lower cross member (3).

In the attached tables some components have been indicated with abbreviations that are explained below:

Ml = asynchronous motor

Pl = pump

Vl = pump unloading solenoid valve V2 = accumulator unloading solenoid valve on safety lock

V3 = accumulator insertion solenoid valve V4 = safety valve on control unit

V5 = pump protection non-return valve V6 = circuit separation non-return valve V7 = accumulator oil side safety valve V8 = proportional direction valve V9 = safety valve

BLl = accumulator block

BL2 = crowning block

Tl = pressure transducer ACC = accumulate (s)

UT = position transducer on upper crosspiece

LT = position transducer on lower crosspiece

CNC = numerical control

Yl = left cylinder

YYl = left cylinder target quota (quota to which the left cylinder of the press must be brought to carry out the set bend) Y2 = right cylinder

YY2 = right cylinder target quota (quota to which the right cylinder of the press must be brought to carry out the set bend) QUT = quota detected by the UT transducer on the upper crosspiece

QLT = quota detected by the LT transducer on the lower crosspiece

The device comprises a pump (4, PI) adapted to charge at least one accumulator (5, ACC), said accumulator being able to control said lower crosspiece (3) by means of a proportional direction valve (6, V8).

The proportional direction valve (6, V8) has a positioning of the cursor that is continuous and proportional to the current that passes through the coils / solenoids mounted therein; in the specific case, said proportional direction valve (6, V8) has three possible positions between which the cursor can move, affecting them both partially and completely.

There is a first rest position with closed centers in which there is no communication between the various branches between the various branches P (branch under pressure), T (discharge), A (use) and B (use) that arrive / depart from said / from said proportional direction valve (6, V8) which acts like a plug, preventing the passage of oil in any direction.

There is a second position, indicated with V8A, with crossed centers, in which branch P is put in communication with branch B; in this condition the oil flows towards the crowning jacks (7) of the lower crosspiece (3); branch T is also put in communication with branch A; in this condition, since A is plugged, nothing happens.

There is a third position, indicated with V8B, with straight centers: branch P is thus put in communication with that A (and since A is plugged, nothing happens) and branch T with that B: in this case it is discharged the oil coming from the crowning jacks (7).

When the machine or press is switched on, the pump (4, PI) is activated: in this phase, a motor (8, M) starts up which, by turning the pump (4, PI), begins to circulate the oil in the circuit .

The oil passes through a first valve (9, V5) which is a protection non-return valve for the pump (4, PI); it is a non-return valve that prevents the flow of oil towards the pump (4, PI) while it allows that towards the user.

In this condition the circuit is not pressurized as the fluid is discharged through a first solenoid valve (10, VI), which is at rest.

The first solenoid valve (10, VI) in the rest position drains the circuit on the tank (11), while in the VIA position it prevents the oil from flowing towards the tank (11), ie it acts as a plug.

To send the circuit under pressure, all the drains to the tank (11) must be closed, therefore the first solenoid valve (10, VI) is energized which moves to the VIA position and, if there is a safety lock (12) for accumulators ( 5, ACC), as illustrated in Figure 2, a second solenoid valve (13, V2) is also excited which in turn moves to position V2A.

The proportional direction valve (6, V8) is in the rest position with the centers closed, ie with Ρ, Τ, Î ‘and B plugged; the oil cannot cross it and therefore the part of the circuit upstream of it is pressurized.

In the configuration of the previous case, the accumulator (5, ACC) is also charged, since the first valve (9, V5) and a second valve (14, V5) and a third solenoid valve (15, V3), the the first two simple non-return and the last non-return in the rest position, prevent the flow of oil only downwards; consequently, once the circuit is under pressure, the accumulator (5, ACC) begins to charge.

When a pressure transducer (16, T1) sends the signal that the reference pressure (target) has been reached, the first solenoid valve (10, VI) is put to rest and the oil flows back through it. 'last from the pump (4, P) to the tank (11).

Given the configuration of the third solenoid valve (15, V3) at rest, the accumulator (5, ACC) remains pressurized.

Once the preparatory phase for switching on the machine or press has been completed, the bending cycle can begin; first there is a rapid descent of the upper crosspiece (2) and then the phase of approaching the sheet to be bent (not shown) begins at working speed.

Shortly before the sheet to be bent interacts with the lower crosspiece (3), the pump (4, PI) is re-inserted into the circuit by activating the first solenoid valve (10, VI) bringing it to the VIA position.

A situation of equilibrium is reached as regards the pressures, between the branches upstream and downstream of the third solenoid valve (15, V3), which therefore can be in position V3A so that the accumulator oil (5 , ACC) can flow into the circuit; as long as this situation of balance of pressures remains, nothing happens.

Upstream of the proportional direction valve (6, V8), which continues to remain at rest, the circuit is under pressure and the accumulator (5, ACC) is inserted.

The bending phase begins and then there is tracking, deformation and crowning in position.

The main cylinders (17a, 17b) of the press press downwards to reach the YYl and YY2 values which will allow the target angle of the sheet being bent to be reached.

As this phase progresses, the upper crosspiece (2) deforms; the numerical control or computer (18, CNC) begins to compare the deformation values of the upper cross member (2) with those of the lower cross member (3), measured respectively by special position transducers (19, UT) and (20, LT) and acts accordingly; its objective is to make the deformation of the lower crosspiece (3) equal the deformation of the upper crosspiece (2).

To achieve this, the crowning jacks (17a, 17b) must be opened more or less according to need; the 'more or less' is obtained by operating on the proportional direction valve (6, V8), moving the cursor continuously, in proportion to the supply current of the coils, between positions V8A and V8B.

Moving towards the V8A position, the oil flows towards the crowning jacks (17a, 17b), pressurizing them and causing them to open.

Moving towards position V8B depressurizes the crown and consequently decreases the deformation of the lower central crosspiece (3).

The numerical control or computer (18, CNC) therefore operates as follows: if the position (QUT) detected by the transducer (19, UT) on the upper crosspiece (2) is greater than the position (QLT) detected by the transducer (20, LT) on the lower cross member (3) the cursor of the proportional direction valve (6, V8) is made to move towards the position V8A and the deformation of the lower cross member (3) is increased.

If, on the other hand, QUT <QLT, the spool of the proportional direction valve (6, V8) is made to move towards position V8B and the deformation of the lower cross member (3) is reduced.

If QUT = QLT, the spool of the proportional direction valve (6, V8) is made to move towards the rest position and the deformation of the lower cross member (3) is kept constant.

Everything happens in a continuous and dynamic way; as the two deformations approach, the proportional direction valve (6, V8) approaches the central closed position; as the demand for oil decreases, the excess oil recharges the accumulator (5, ACC).

Once the main cylinders (17a, 17b) of the machine or press have reached the target heights YY1 and YY2 and the deformation values of the two lower (3) and upper (2) crosspieces are the same, it means that the piece has been bent. , then the relaxation phase begins, in which the pressure in the main cylinders (17a, 17b) is reduced and the structure relaxes.

The upper crosspiece (2) returns to the horizontal and consequently, since the crowning is still active, the lower crosspiece (3), which continues to follow the deformed one, returns to horizontal discharging the excess oil from the crowning jacks (7).

After the relaxation phase, with the upper (2) and lower (3) crosspieces now perfectly horizontal, the proportional direction valve (6, V8) is returned to the rest position and you are ready to restart with a new cycle of fold by recharging the accumulators (5, ACC) if necessary.

It should be noted that in circuits with accumulators (5, ACC) with a capacity greater than one liter, and therefore with a safety lock (12) certified according to the mandatory standards of the country of destination, once the machine or press is switched on, the second solenoid valve (13, V2) remains always active (drain closed) so that the oil cannot drain into the tank (11); it can be deactivated at the end of the day.

The maximum pressure in the circuit is determined first by the third safety valve (21, V4) and then by the fourth safety valve (22, V7) and by the fifth safety valve (23, V9).

The pressure of the accumulator (5, ACC) never drops below the minimum value necessary for crowning.

The proportional direction valve (6, V8) does not determine the pressure in the circuit, but merely allows quantities of oil to pass either towards the crowning or towards the discharge, proportional to the current that passes through the coils that move the cursor.

The first solenoid valve (10, VI) and the third solenoid valve (15, V3) are basically on-off - open / closed valves; the third solenoid valve (15, V3) actually 'from bottom to top' always lets the oil flow, while it acts as on-off only from top to bottom.

The use of several accumulators (5, ACC) of less than one liter capacity connected together can be envisaged.

In practice it has been found that the invention has achieved the above mentioned aim and objects, having obtained a greater energy saving with respect to the known art exposed: the device allows to move small volumes of oil, but, when it intervenes, these volumes are supplied in very short times; therefore there are large oil flows and therefore many liters / minute.

The use of the accumulator makes it possible to use a pump with a small flow rate, while delivering, within the set pressure range, large instantaneous flow rates of oil.

It should also be noted that the device allows to have the necessary quantity of oil only when needed, without draining it unnecessarily.

Thus, greater energy savings are achieved thanks to the use of the proportional direction valve (6, V8): in the known art the deformation of the jacks was controlled by a proportional pressure which operated this control, acting on the pressure of the circuit, but to doing this drained large quantities of oil and therefore unnecessarily 'wasted' large amounts of energy.

the device instead allows to have a position control through a proportional direction valve, therefore, a decidedly lower quantity of oil is drained and laminated than before, thus resulting in greater 'energy saving'.

There is also a lower installed power: the main purpose of the pump (4, PI) is to charge the accumulator (5, ACC) in dead times, while the supply of the crowning jacks (7) is done almost exclusively by the latter .

It is thus possible to install a pump (4, Pi) with a lower flow rate than a known type circuit without accumulator.

Finally, there is a greater reaction speed of the crowning, due to the greater instantaneous flow rate delivered by the accumulator (5, ACC) and the use of the proportional direction valve (6, V8) compared to the traditional known type circuit where the feeding of the crowning was carried out by a larger pump and a proportional pressure was used.

With the device the cycle time is reduced and productivity increases.

The materials used as well as the dimensions that constitute the individual components of the invention may of course be more pertinent according to specific requirements.

The different means for carrying out certain different functions will certainly not have to coexist only in the illustrated embodiment, but may be present per se in many embodiments, including those not illustrated.

The characteristics indicated as advantageous, convenient or the like may also be missing or be replaced by equivalents.

Claims (10)

CLAIMS 1. Device (1) for the active crowning of bending presses comprising an upper crosspiece (2) and a lower crosspiece (3), which is characterized in that it comprises a pump (4, PI) able to charge at least one accumulator ( 5, ACC), said accumulator (5, ACC) being able to control said lower cross member (3) by means of a proportional direction valve (6, V8). 2. Device as in claim 1 which is characterized by the fact that said proportional direction valve (6, V8) has a positioning of the cursor that is continuous and proportional to the current flowing through the coils / solenoids mounted therein, said proportional direction valve ( 6, V8) presenting three possible positions, between which said cursor can move going to affect them both partially and completely, a first rest position with closed centers in which there is no communication between the various P branches (branch under pressure ), T (drain), A (use) and B (use) arriving / departing from said proportional direction valve (6, V8) which acts as a plug, preventing the passage of oil in any direction , a second position V8A with crossed centers, in which said branch P is put in communication with said branch B so that in this condition the oil flows towards the crowning jacks (7) of said lower crosspiece re (3) and said branch T is also put into communication with said branch A, plugged, a third position V8B with said straight centers so as to put said branch P in communication with said branch A, plugged, and said branch T with said branch B so that the oil coming from said crowning jacks (7) is discharged. 3. Method for the active crowning of press brakes comprising an upper crosspiece (2) and a lower crosspiece (3), which is characterized by the fact that, once all the drains have been closed to a tank (11), to send the circuit under pressure, a first solenoid valve (10, VI) is energized which moves to the VIA position and, if there is a safety lock (12) for at least one accumulator (5, ACC), a second solenoid valve (13, V2) is also excited ) which in turn moves to the V2A position, as there is a proportional direction valve (6, V8) in the rest position with the branches (Ρ, Τ, Î ', Î') closed which allows to pressurize the part circuit upstream of it, also obtaining the loading of said at least one accumulator (5, ACC) since a first valve (9, V5) and a second valve (14, V5) and a third solenoid valve (15, V3), the first two simple non-return and the last non-return in the rest position prevent the flow of the sol oil or downwards so that once the circuit is under pressure said at least one accumulator (5, ACC) begins to charge. 4. Method as in claim 3 which is characterized by the fact that when a pressure transducer (16, Tl) sends the signal that the reference pressure (target) has been reached, said first solenoid valve (10, VI) and the oil flows back through the latter from a pump (4, P) to said tank (11), the configuration of said third solenoid valve (15, V3) at rest allowing said at least an accumulator (5, ACC) to remain pressurized. 5. Method as in claims 2 and 4 in which, once the preparatory phase for switching on of said bending press has been completed, the bending cycle begins with an initial rapid descent of said upper crosspiece (2) and then a phase of approaching the sheet metal to be bent at the working speed, which is characterized by the fact that just before said sheet to be bent interacts with said lower crosspiece (3), said pump (4, PI) is inserted again in the circuit, activating said first solenoid valve (10, VI) bringing it into the VIA position so that a situation of equilibrium is reached as regards the pressures, between the branches upstream and downstream of said third solenoid valve (15, V3), which therefore can be in position V3A so that the oil present in said at least one accumulator (5, ACC) can flow into the circuit. 6. Method as per claims 2 and 5 which is characterized by the fact that at the beginning of the bending phase the main cylinders (17a, 17b) of said upper crosspiece (2) press downwards to reach predetermined levels YY1 and YY2 designed to allow reaching the target angle of the sheet metal that is in the bending phase as this phase progresses, said upper crosspiece (2) deforming while a numerical control or computer (18, CNC) begins to compare the deformation values of said upper cross member (2) with those of said lower cross member (3), measured respectively by appropriate position transducers (19, UT) and (20, LT), in this phase by making themselves open, partially or totally, said crowning jacks (17a, 17b) by operating on said proportional direction valve (6, V8) by moving its spool continuously, proportionally to the supply current of the coils, between positions V8A and V8B to ensure that the defo the deformation of said lower cross member (3) equals the deformation of said upper cross member (2). 7. Method as in claims 2 and 6 which is characterized by the fact that moving towards said position V8A the oil flows towards said crowning jacks (17a, 17b), pressurizing them and causing them to open, while moving towards said position V8B depressurizes the crowning and consequently the deformation of said lower cross member (3), said numerical control or computer (18, CNC) is reduced by operating so that if the quota (QOT) detected by said transducer (19, UT) on said upper cross member (2) The cursor of said proportional direction valve (6, V8) is made to move towards said position V8A and the deformation of said lower cross member (3), if instead it is QUT <QLT the cursor of said proportional direction valve (6, V8) is made to move towards said position V8B and the deformation of said lower cross member (3) is reduced, if QUT = QLT the cursor of said proportional direction valve (6, V8) is made to move towards the rest position and the deformation of said lower crosspiece (3) is kept constant. 8. Method as per claims 2 and 7 which is characterized by the fact that as the two deformations approach, said proportional direction valve (6, V8) approaches the central closing position while as the oil request decreases, the excess recharges said at least one accumulator (5, ACC). 9. Method as per claims 2 and 8 which is characterized by the fact that once said main cylinders (17a, 17b) of said bending press have reached said heights YY1 and YY2 and à values of the deformations of said two lower crosspieces ( 3) and upper (2) are the same, the piece appears to have been bent and the relaxation phase begins, in which the pressure in said main cylinders (17a, 17b) and said upper crosspiece (2) and lower crosspiece (3) is reduced ) return to horizontal discharging the excess oil from said crowning jacks (7). 10. Device or method as per one or more of the preceding claims which is characterized by the fact that the maximum pressure in the circuit is determined by a fourth safety valve (21, V4), by a fifth valve (22, V7) and by a sixth safety valve (23, V9), called proportional direction valve (6, V8) limiting itself to passing either towards the crowning or towards the discharge quantities of oil proportional to the current passing through the cursor.