CH625979A5 - Adjusting device for a sheet levelling machine for the adjustment of the levelling gap - Google Patents

Description

The invention relates to an adjusting device for a straightening machine for straightening sheet metal and flat materials according to the preamble of patent claim 1.

In older straightening machines for sheet metal and the like, the infeed takes place between an upper and a lower roller mill, i.e. the setting of the straightening gap between the straightening rollers, for example using handwheel-operated spindles, and the setting values can be monitored by dial indicators or comparable mechanical measuring devices. The setting of such straightening machines is relatively cumbersome and takes place rigidly without the possibility of flexible adaptation to different material conditions.

From DE-AS 1 452 867 an adjusting device for straightening machines of the type mentioned is known, in which the delivery of the nip is regulated hydroelectrically via pressure-actuated cylinder pairs at the straightening material inlet or straightening material outlet. The hydraulic cylinders are operated by a common motor via a reduction gear. This motorized roller mill adjustment leads to difficulties insofar as the unavoidable play in the transmission makes fine adjustment with slightly different infeed in the inlet and outlet area of the order of magnitude of one to two hundredths of a millimeter impossible.

It is also not possible to move the rollers apart and to deliver the roller mills to their final dimensions fully automatically with the known hydroelectric adjustment device.

The invention is therefore based on the object of improving an adjusting device in such a way that an automatic, possibly remote-controllable setting of the machine is made possible without substantial intermediate control and readjustment with substantially smaller material deviations than previously. In particular, there is no need to readjust the roll feed and measure each time the material is run.

This technical problem is solved according to the invention with an adjusting device which has the features specified in the characterizing part of patent claim 1.

Advantageous developments of the invention are characterized in the dependent claims.

In order to apply the necessary feed force between the upper and lower roller mill, according to the invention the cylinder spaces intended for guiding the pistons connected to the pull piston rod are divided by the piston into two annular spaces each with a different cross section. This different cross section results from the fact that the part of the piston rod facing the lower roller mill has a smaller diameter than the upper guide part of this piston rod, so that with the same pressure medium pressure in the annular space above the piston and below the piston, this together with the piston rod due to the larger cross section in the lower part Annular space is pulled up and thus the delivery of the upper to the lower roller mill.

In order to have the desired degrees of freedom to compensate for material fluctuations, in particular between the leveling material inlet and outlet in the relative position between the upper and lower roller mill, in a preferred embodiment it is provided that the hydraulic drive of the two pairs of displaceable pistons (one pair each To accommodate the target material inlet or outlet) in the upper roller mill and to provide the pistons with a ball joint at the free end on the underside, which rests against a spherical cap-shaped bearing shell on the lower roller mill.

If, however, the system were designed rigidly in the manner specified so that the same pressure would prevail in the lower and upper annular space of each cylinder chamber, the delivery forces could only be adjusted by a corresponding change in the pressure of the pressure medium source. Furthermore, the straightening machine would then only have to be designed such that the same infeed forces always prevail at the straightening material inlet or outlet, which is particularly undesirable if small changes in thickness are to be taken into account. In fact, straightening comes with many flat materials

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Machines of this type are close to a cold rolling process because there is a slight decrease in thickness. For this reason, an independent, regulated adjustment of the pressure in one of the annular spaces of each cylinder chamber with respect to the pressure in the other annular space is desirable. The invention provides this possibility by using servo pressure reducing valves, which convert a continuously adjustable electrical value, which can be specified via a control circuit, into a continuously adjustable reduced pressure value. These servo pressure reducing valves can either be provided for a pair of pulling pistons, for example at the leveling material inlet or outlet, so that in this case there are two additively or subtractively coupled control loops for setting the delivery pressure at the inlet or outlet. In order to allow even greater flexibility with regard to the degrees of freedom, each pulling piston arrangement is assigned its own servo pressure reducing valve with a corresponding control loop, so that, for example, four control loops coupled to each other result.

In a further advantageous embodiment, it is also provided that the system is assigned a subordinate controller, by means of which the setpoint value, that is to say the respective undersize, can be set in relation to a certain target material. Since a certain type of machine also has a minimum dimension of the possible, still processable material thickness, there is a stop to determine the lower limit of the setpoint setting, which comes into operation when the setpoint setting is at the lower material limit and the actual value to the lower level material thickness that can still be processed.

The invention and advantageous details are explained in more detail below with reference to the drawing in an exemplary embodiment.

The single figure shows a schematic representation of the assignment of an upper and lower roller mill of a straightening machine which is equipped with an automatic feed and adjustment device according to the invention.

As can be seen in the drawing, a straightening machine of the type mentioned above has an upper roller mill A with positively driven straightening rollers 1, 3, 5, 7 ... and a lower roller mill B with lower straightening rollers 2 standing on a gap with the straightening rollers of the upper roller mill, 4, 6, 8, 10 ... on. The structural design of the two roller mills and the drive, the support, storage and arrangement of the straightening rollers etc. are not the subject of the invention with the exception of the connecting and feed elements between the upper and lower roller mills and the control and regulating elements associated with these feed elements. The distance between the straightening rolls 1, 3, 5, 1 ... of the upper and the straightening rolls 2, 4, 6, 8, 10 ... of the lower roll mill can be adjusted, i.e. adapt to the material thickness d of a straightening good C passing between these roller rows in the direction of arrow a in a manner described in more detail below.

As already generally stated above, the infeed between the upper and lower roller mill takes place via a total of four pistons, each arranged in pairs, once at the leveling material inlet or at the leveling material outlet, of which one, namely a piston Fi at the leveling material inlet and one, in the schematic longitudinal sectional illustration Piston F2 are shown at the leveling material outlet. The pistons F1; F2 protrude into an assigned cylinder chamber Ki or K2 in the upper roller mill and are rigidly connected to a piston Ei or E2 which is displaceable in the respective cylinder chamber Kj or K2 and merges on the opposite side into a piston rod section Dj or D2. The piston rods Ft and F2 and the piston rod sections Dj and D2 are guided in the end walls of the cylinder chamber Kj and K2 pressure-tight. As shown, the pull piston rods Ft and F2 have a smaller diameter than the piston rod sections Dt and D2 adjoining the pistons Ei and E2 on the upper side, so that the cylinder chamber Ka. Is located in the annular chamber section Kiy, K2y below the piston Ex, E2 , K2 results in a larger cross section on the displaceable piston Ei, E2 for a pressure medium than due to the larger diameter of the piston rod parts Dx, D2 in the annular chambers Kix, K2x located above the piston Ei, E2. In other words: If the same pressure is applied to the upper annular chambers Kix, Kiy and the lower annular chambers Kly, K2y, the pistons El5 E2 slide in the cylinder chambers K1; K2 upwards and thereby pull the lower roller mill B upwards or push the upper roller mill A downwards. The upper annular chambers Kix, K2x are supplied with a pressure medium from a pressure medium source S via a branching point Pj or P2. The lower annular chambers Kly, K2y, however, are from the branch point P1; P2 from a servo pressure reducing valve Ot or 02 is pressurized with a pressure PZi or Pz2, which is generally lower than the pressure at point Pi, P2. The structure of the servo pressure valves Oi, 02 is known per se. These valves are able to continuously adjust within certain limits, e.g. convert electrical value into a correspondingly continuously adjustable, in particular reduced pressure value. These valves C ^, 02 are connected to a return tank via a discharge line, so that pressure medium to be discharged from the lower annular chambers Kiy, K2y can get directly into the return tank T. A dash-dotted line and the note L also indicate an inevitable leakage loss.

On the side of the servo pressure reducing valves Oi, 02 corresponding to the reduced pressure Pzi, Pz2, there is a pressure measuring cell Mi, M2 which converts the pressure prevailing on the underside of the pistons Ea, E2 into a corresponding value ai, a2, for example an electrical voltage, implements. This value arrives at a difference-forming element Dix or Di2 and is compared with a value which can be predetermined by an adjusting element Rx or R2, for example a digitally adjustable potentiometer, and which corresponds to a desired pressure setting. The resulting comparison value is amplified by a control amplifier Lj or L2, for example made up of several cascade-connected individual amplifiers, and reaches the input of an output amplifier Na or N2, at the output of which the manipulated variable, via a further difference-forming element Dsi or Ds2, the function of which will be explained yt or y2 occurs, which determines the setting of the servo pressure reducing valve Oi or 02. The one control circuit for the pressure monitoring in the respective lower annular chamber Kly, K2y is thus outlined in relation to the pressure in the respective upper annular chamber Klx, K2x.

A further common controller U, on which a default value for an undersize of the material thickness can be set, is subordinate to the control circuit for predeterminable pressure adjustment, which is described in duplicate or multiple, for example a quadruple version. In this case too, it is, for example, a voltage value transmitter, which is implemented, for example, by a digital potentiometer. This subordinate controller U is therefore used for setting the setpoint; it does not prevent the roller mills from moving apart, for example when introducing the leveling material.

An actual value transmitter It or I2 is used to determine the actual value of the actual gap setting between the roller mills, which is mechanically connected on the one hand, as shown schematically in the drawing, to the upper and on the other hand to the lower roller mill. This actual value encoder Ii or I2 delivers an analog signal βx or

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p2. which corresponds to the currently set actual value of the gap distance between the straightening rolls of the upper and lower roll mill.

In order to obtain a comparison between the desired target value that can be set on the controller U and the actual value, the output signal supplied by the subordinate controller U and the output signal ß t or ß2 of the actual value transmitter I] or I2 switched to a difference forming element Drx or Dr2. The difference value obtained is amplified via an amplifier Mj or M2 and reaches the already mentioned difference-forming element Dst or Ds2 as a correction signal. The circuit supplemented by the subordinate controller U thus not only enables a regulated pressure setting, but also a correction setting with regard to the gap distance between the straightening rolls of the upper and the lower roll mill. This enables fully automatic operation of the straightening machine, since the infeed forces are not only monitored for a certain straightening pressure, but also for a certain straightening dimension.

A stop element Qj or Q2 is also assigned to the actual value transmitter on the input or output side, by means of which the undersize of the sheet thicknesses that can just be processed by a certain straightening machine is determined. If the straightening gap becomes so narrow that this undersize is reached, the encoder arm of the upper roller mill connected to the actual value encoder It or I2 runs onto the stop member Qi io or Q2 and limits further movement of the roller mills.

With the invention, the task was solved in its entirety, so that monitoring, in particular dial gauge monitoring and manual delivery between 15 roller mills is eliminated. In an improved embodiment, fully automatic working is made possible by using a subordinate control loop.

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Claims (7)

625 979 1. Adjusting device for a straightening machine for straightening sheet metal and flat materials with a lower and an upper roller mill, which each hold the same distance from each other, arranged at right angles to the material flow direction, upper and lower positively driven straightening rollers, the upper roller mill and the lower roller mill Relative infeed in the transverse direction with respect to the material to be straightened through two pairs of piston rods displaceable by means of pressure medium are coupled to one another in a force-locking manner, one pair of which, leaving an intermediate distance free for introducing the material to be straightened, into the machine in the area of the material inlet and the other pair at a corresponding distance in the region of the Is arranged, characterized in that the piston rods (Fi or F2) are designed as tension elements that each piston rod (Fj or F2) in the upper roller mill (A) in a guide bore of a cylinder space (Kx or K2) is broken, which is divided by a piston connected to the piston rod (Ei or E2) into two annular spaces (Klx, K2x or Kiy, K2y), of which the respective upper annular space (Kix or K2x) has a smaller cross section on the piston than the respective lower annulus (Kty or K2y), and that the respective upper annulus directly to an adjustable pressure medium source (S) and the respective lower annulus (Kiy or K2y) via an associated servo pressure reducing valve (Ot or 02) is connected to the pressure medium source. 2. Adjusting device according to claim 1, characterized in that the piston rods (Fx or F2) attack at least on one roller mill side (W) via a ball and socket arrangement (Gì, Hi or G2, H2), so that relative inclinations caused by uneven target material can be compensated in the transverse and / or longitudinal direction. 2nd PATENT CLAIMS 3. Adjusting device according to claim 1 or 2, characterized in that the servo pressure reducing valves (Ox or 02) are adjustable at the leveling material inlet and outlet and can be preselected differently in their respective settings. 4. Adjusting device according to one of the preceding claims, characterized in that the non-positive feed of the roller mills (A, B) can be limited to a minimum value of the column setting (d) by stops (Qt or Q2). 5. Adjusting device according to claim 4, characterized in that the stops (Qi or Q2) for changing the minimum value of the column setting (d) are adjustable. 6. Adjusting device according to one of the preceding claims, characterized in that each cylinder / piston arrangement Ei, Fa or E2, F2) is assigned its own force control circuit, so that different infeed forces in the longitudinal and transverse directions of the material to be straightened (C) are adjustable. 7. Adjusting device according to one of the preceding claims, characterized in that the force control loops are assigned a common subordinate controller (U) on which a setpoint value of the material thickness can be set.