Patent Application
20230321937
The invention relates to a method for operating an elastically mounted forming machine which is path-bound or force-controlled, method in which a working stroke of a ram device operatively connected to the drive is carried out by means of a drive, and a predefined forming process is carried out on a workpiece by a motion of the ram device during the respective working stroke, in particular in interaction of an upper tool located on the ram device with a lower tool located on a tool table, wherein the inertial forces and/or moments of inertia occurring during operation due to the initiation of the working stroke and/or due to an imbalance in the drive are at least partially compensated.
The operation or the control of such an elastically mounted path-bound or force-controlled forming machine is well-known in this field. Such machines can be configured, depending on the embodiment, for pressure forming, tensile compressive forming, bending or thrust forming. For path-bound forming machines, for example path-bound presses, the travel of the ram device (bear) is determined by the kinematics of the drive of the machine. The drive is generally carried out by an electric motor that drives a flywheel that can be connected to the ram device by clutch engaging for initiating the working stroke. Force-controlled forming machines have a controllable drive, in particular a hydrostatic drive, for example as a pump, or a servomotor drive by which a ram device permanently operatively connected therewith is moved after the respective activation of the drive for initiating the working stroke for carrying out the forming process. The time of initiation and the carrying out of the working stroke of operator-controlled machines generally takes place by means of a so-called two-hand activation.
It is common to path-bound as well as to force-controlled forming machines that they are exposed to occurring inertial forces and/or moments of inertia during the carrying out of the forming process. They can be caused, for example, with permanently rotating drive shafts, by clutch engaging and disengaging of the ram device or by an imbalance in the drive of a force-controlled forming machine and result in a tumbling and/or tilting motion of the forming machine. Such motions can cause an increased mechanical stress of the machine and possibly result in a non-compliance of the dimensional tolerances at the formed workpiece. The generated inertial forces or moments of inertia cause, because of an elastically bearing of the forming machine on a supporting foundation, for example on a foundation soil, a excitation of the rigid body modes of this vibratory system that are defined by the forming machine and the elastic bearing, which causes the described tumbling and/or tilting motion of the machine relative to the foundation on which the forming machine bears with an elastic bearing.
Active measures for acting on the undesired whole body movements of such a forming machine are known in this field, in particular the eradication of vibration phenomena by installing an appropriately adapted additional vibratory system, designated in this field as a damper, on the mass to be steadied. For example, the published patent application DE 10 2008 046 763 A1 relates to a generic high-speed press with inertial moment compensation for which a counterweight is provided that serves for taking over the reactive power of the ram, wherein the phase of motion of the counterweight is adapted to the phase of motion of the ram. The published patent application DE 2806584 relates to an also generic eccentric press on which a compensating device with a movable mass part is placed for mass balancing, that has driving elements for driving the mass part in antiphase with preserved angles relative to the eccentric shaft.
The providing of such compensating devices for the respective forming machine is connected to an increased expenditure on the device.
JP 2008-290126A relates to the forming operation with a press. This press is supported by a spring damper system on a foundation. The travel of the main frame is detected by a displacement sensor. Moreover, a speed sensor is provided for detecting the first time derivation. The angular speed and the angular position of the crank drive are the control variables that are influenced to reduce the vibrations on the press.
The aim of this invention is, for a conventional elastically mounted forming machine, to make available at least an attenuation of the described rigid body motion of the forming machine in operation without a significantly expenditure on equipment having to be provided as in the prior art.
With the method according to the invention, a working stroke of a ram device operatively connected to the drive is carried out, working stroke with which a predefined forming process is carried out on a workpiece due to a motion of the ram device during the respective working stroke, in particular in interaction of an upper tool located on the ram device with a lower tool located on a tool table, wherein the inertial forces and/or moments of inertia occurring during operation due to the initiation of the working stroke and/or due to an imbalance in the drive are at least partially compensated. The method according to the invention is characterized in that at least one kinematic variable of a rigid body motion of the elastically mounted forming machine is detected during the operation thereof, in particular continuously detected, wherein the time at which the working stroke is initiated is adapted to an instantaneous phase position of the at least one kinematic variable, in particular path s(t), speed v(t) and/or acceleration a(t) of the rigid body motion for generating inertial forces and/or moments of inertia so that the rigid body motion of the forming machine is counteracted.
The method according to the invention results in a reduction of the amplitude of a tumbling and/or tilting motion of the forming machine. Such a tumbling or tilting motion of the forming machine substantially constitutes a rigid body motion of the forming machine excited by the occurring inertial forces and/or moments of inertia in a vibratory system formed by the forming machine itself as well as an elastic bearing device with which the forming machine is elastically mounted on a supporting foundation. According to the invention, this vibration reduction can be made available without a significantly increased expenditure on the device being necessary as in the prior art.
Instead, in the method according to the invention, the control of the initiation of the working stroke takes place depending on a present rigid body motion of the forming machine in the vibratory system so that the inertial forces and/or moments of inertia are introduced into the vibratory system of the rigid body motion of the forming machine by a phase-exact initiation of the working stroke caused by the clutch engaging of the ram device and/or by an imbalance in the drive in such a manner that they counteract the present rigid body motion of the forming machine. The excitation of the rigid body motion can take place due to the occurring inertial forces and/or moments of inertia, and be for example impact-type with a predefined amplitude and duration.
In case of operator-controlled machines, it can insofar be provided that, after a two-hand activation by the operator, the above mentioned method according to the invention is carried out for controlling the operation of the forming machine, i.e. after the two-activation, at least one kinematic variable of the rigid body motion of the elastically mounted forming machine is detected during the operation thereof and the time of the initiation of the working stroke is adapted to an instantaneous phase position of the at least one kinematic variable of the rigid body motion in order to generate inertial forces and/or moments of inertia so that the rigid body motion of the forming machine is counteracted. According to the invention, it can however also be provided for operator-controlled machines that the method according to the invention for controlling the operation of the forming machine is permanently carried out or permanently runs after a start of operation of the forming machine during which at least one kinematic variable of the rigid body motion of the elastically mounted forming machine is detected and the time of the initiation of the working stroke is adapted to an instantaneous phase position of the at least one kinematic variable of the rigid body motion in order to generate inertial forces and/or moments of inertia so that the rigid body motion of the forming machine is counteracted and wherein the working stroke is only initiated after a two-hand activation has been carried out by the operator for the working stroke to be initiated. This being, a control device of the forming machine that is equipped and configured for the control of the operation according to the invention of the forming machine can detect a signaling induced by the two-hand activation of the operator, in particular as an electric signal, and process it for implementing the method according to the invention.
The method according to the invention thus results in a significantly reduced deflection of the forming machine compared to an uncontrolled mode of operation. The method according to the invention for operating the elastically mounted forming machine makes possible the faster achievement of a state of the forming machine with a lower motion elongation or amplitude. Thus, a subsequent working stroke can possibly start earlier with the advantage of a faster cycle sequence during operation which can be advantageous in particular for an automatic feed of the forming machine for which the respective working piece has to be positioned accurately. Moreover, because of the lower stress of the elastic bearings of the forming machine, the lifetime of present bearings can be increased or allows for the use of bearings with smaller dimensions.
It should be noted that the at least one kinematic variable of a rigid body motion of the elastically mounted forming machine can be, for example, a path or angle deflection from a respective rest position, a time derivation of these variables or the corresponding results of a numerical simulation of the rigid body motion of the forming machine, carried out previously or simultaneously with the operation of the forming machine, for determining a respective speed and/or acceleration. Appropriate kinematic variables can be defined in particular with respect to the different modes of the system for the description of the motion of the elastically mounted forming machine. The method according to the invention can basically be applied to all the degrees of freedom of the rigid body motion of the forming machine.
Accordingly, it is within the scope of the invention that the detection of the at least one kinematic variable of the rigid body motion is carried out for example by means of a measurement with a motion sensor and/or by means of a calculation, in particular within the scope of a simulation of the rigid body motion of the forming machine.
Further advantageous characteristics and further developments of the invention are indicated in the following general description, in the figures, in the description of the figures as well as in the subclaims.
It can appropriately be provided that the operation of the forming machine is controlled by a machine control that activates the drive for carrying out the forming process, possibly after the presence of a two-hand activation signal induced by an operator at the time of the initiation of the working stroke and/or activates a coupling device located between the drive and the ram device for establishing an operative connection between the drive and the ram device for carrying out the forming process. In the first case, the matter can be for the forming machine of a force-controlled forming machine for which the drive is permanently connected to the ram device and in the second case of a path-bound forming machine for which an operative connection can be established between the drive and the ram device by clutch engaging a controllable coupling and can be released upon clutch disengaging.
As explained, the elastically mounted forming machine can carry out a rigid body motion excited by the occurring inertial forces and/or moments of inertia. It has become apparent, in particular during the operation of stroke-forced forming machines, for which the excitation, in particular an excitation of the rigid body motion, is carried out substantially during the initiation of the working stroke or during clutch engaging, that a time range can be appropriately selected for adjusting an optimal time for initiating the working stroke or for clutch engaging the ram device, time range within which a global maximum of the first time derivation of the course of a deflection of the forming machine is situated.
The clutch engaging time is preferably situated immediately before reaching this global maximum. With respect to a harmonious vibration, immediately before can mean, depending on the embodiment, <30°, <20°, in particular <10°, before reaching this global maximum in the first time derivation of the course of the deflection of the forming machine. It can also be provided that the excitation moment exactly coincides with the reaching of this global maximum in the first time derivation of the course of the deflection of the forming machine. Basically, the time of clutch engaging of the ram device or of the initiation of the working stroke is selected so that a motion of the forming machine is induced to a direction that is in opposite direction of the temporarily deflection of the forming machine, i.e. the excitation should take place in phase opposition.
It became apparent in particular during the operation of force-controlled forming machines, for which the excitation of the rigid body motion substantially takes place due to an imbalance of the drive during the working stroke and/or the return stroke of the ram device, that a time for initiating the working stroke can appropriately be selected in such a manner that the excitation of the rigid body motion of the forming machine that can take place impulsively in particular during the working stroke and/or the return stroke, takes place due to the occurring inertial forces and/or moments of inertia within a time period in which a global maximum of the first time derivation of the course of a deflection of the forming machine is situated. The time of initiation of the working stroke can preferably take place so that the time of excitation of the rigid body motion is situated immediately before reaching this global maximum. With respect to a harmonious vibration of the rigid body motion that can be assumed approximately in cases of a rigid body motion, “immediately before” can mean, depending on the embodiment, <30°, <20°, in particular <10°, before reaching this global maximum in the first time derivation of the course of the deflection of the forming machine. It can also be provided that the time of excitation exactly coincides with the reaching of this global maximum in the first time derivation of the course of the deflection of the forming machine. Basically, the time of the excitation of the rigid body motion is selected so that a motion of the forming machine is generated into a direction that is in opposite direction of the temporarily deflection of the forming machine, i.e, the excitation should take place in phase opposition.
In order to make available the information necessary for the control of the time of clutch engaging the ram device or of the initiation of the working stroke, the at least one kinematic variable of the rigid body motion of the forming machine relative to the supporting foundation is detected by at least one motion sensor. This motion sensor can be configured, for example, as a deflection sensor such as a displacement sensor, a speed sensor or an acceleration sensor. Depending on the embodiment, the motion sensor can be placed in particular on the forming machine itself or on the bearing device. The motion sensor, in particular the acceleration sensor, can detect the magnitude of an elastic deformation on the bearing device, for example of an elastic deformation of an elastomer from which the at least one kinematic variable of the rigid body motion of the forming machine can be determined, in particular can be calculated, for the optimal temporal clutch engaging of the ram device or the initiation of the working stroke.
A multitude of sensors are basically possible as motion sensors for implementing the method according to the invention that detect in particular a deflection, a speed and/or an acceleration of the rigid body motion of the forming machine. The motion sensor can be configured, for example, as a plunger coil sensor or as a resistance sensor. It is also possible to configure the motion sensor as an optical sensor.
A respective output signal of the at least motion sensor is supplied as an input signal of a machine control of the forming machine for making available a corresponding signal to a control device associated to the forming machine, wherein this signal supply can also be wireless. Preferably, several motion sensors can be provided that detect, in particular that measure, one or several kinematic variables of the rigid body motion of the forming machine and, for example make them available to a central control device such as a machine control of the forming machine for carrying out the method according to the invention.
In particular in such embodiments in which the forming machine carries out a complex rigid body motion, it can appropriately be provided that the at least one kinematic variable of the rigid body motion of the forming machine relative to the supporting foundation is calculated on the base of a rigid body simulation model and the time of clutch engaging or of the initiation of the working stroke is defined depending on a measured and of the calculated instantaneous value of the at least one kinematic variable. For example, the time of clutch engaging or of the initiation of the working stroke can be adjusted basically after the calculated kinematic variable, wherein the measured instantaneous value is used as a control variable, wherein, in presence of a predefined difference value, the control is interrupted for safety reasons and the operation completed. It is however possible that the time of clutch engaging or of the initiation of the working stroke is adjusted after the measured kinematic variable, wherein the calculated instantaneous value is used as a control variable, wherein, in presence of a predefined difference value, the control is interrupted for safety reasons and the operation completed.
It can be provided that the at least one kinematic variable of the rigid body motion of the forming machine is calculated relative to the supporting foundation on the base of a rigid body simulation model of the elastically mounted forming machine and the time of the initiation of the working stroke or of the clutch engaging of the ram device is defined depending on an instantaneous value of the at least one kinematic value calculated through the simulation. For coupling the simulation with the real operation of the forming machine, it can preferably be provided that a kinematic variable of the rigid body motion of the elastically mounted forming machine relative to the supporting foundation is measured and a synchronization signal is derived depending on the measurement signal and/or on an operation signal from a machine monitoring device, synchronization signal with which the time sequence of the kinematic variable calculated with the simulation model is synchronized with the real rigid body motion of the forming machine.
It can also be provided to use output signals of a machine monitoring device provided for conventional forming machines that can be arranged in particular for measuring one or several kinematic variables of the rigid body motion of the forming machine or of other operating parameters, together with results of a simulation of the rigid body motion of the forming machine, in order to define the time of clutch engaging the ram device or of the initiation of the working stroke as described in such a manner that the inertial forces and/or moments of inertia introduced into the vibratory system counteract the instantaneous rigid body motion of the forming machine. Thus, the method according to the invention can be carried out for controlling an elastically mounted forming machine without additional expenditure on equipment compared to a conventional method for controlling a conventional forming machine.
Depending on the specific forming machine and the operation thereof, the forming machine can also be exposed to elastic deformations relative to certain sections or components of the machine while executing a working stroke. In order to at least partially reduce such elastic deformation movements for the control according to the invention of the operation of the forming machine, it can be provided to detect a variable of an elastic deformation of a predefined section or component of the forming machine such as a deflection relative to the housing or to a machine foundation of the forming machine, wherein the time of clutch engaging the ram device or of the initiation of the working stroke is adapted to an instantaneous phase position of the one variable of the deformation movement of the predefined section or component of the forming machine for generating inertial forces and/or moments of inertia during clutch engaging or initiating the working stroke so that the elastic deformation movement of the predefined section or of the component of the forming machine is counteracted. Such a section or such a component can comprise, for example, a damping element such as an elastomer body or a shock absorber or even an elastic bend line section resulting from the occurring stress within the forming machine that is thus located in the forming machine and insofar differs from the bearing device by which the forming machine is elastically supported on the supporting foundation.
It can be provided to reduce the rigid body motion of the forming machine as described by the phase-exact clutch engaging of the ram device or the initiation of the working stroke as well as similarly an elastic deformation movement within the forming machine, wherein the movement reduction is set by priority to the rigid body motion of the forming machine or to the elastic deformation movement of a section or of a component of the forming machine, or a compromise is reached to reduce both movements or deflections in roughly equal measure. This being, in equal measure can mean that the respective deflection amplitudes of the rigid body motion of the forming machine and the elastic deformation are substantially equally reduced within the machine.
The method according to the invention for operating or for controlling the operation of a forming machine results in a reduction of a rigid body motion of the forming machine or of an elastic deformation of a section or of a component of the forming machine and can be used in particular to adjust a higher working cycle rate compared to a conventional method so that a higher production rate of the formed products can be achieved when implementing the method according to the invention. It can be provided that in operation a present amplitude value, that has been measured by means of a motion detector or a sensor or that has been calculated through a simulation, of the at least one kinematic variable of the rigid body motion of the forming machine, for example of a deflection into a predefined direction, is compared to a predefined amplitude threshold, and the cycle rate of the forming machine is increased when the present amplitude value is lower than the predefined threshold. The method according to the invention for operating a forming machine can also comprise a regulation of such a deflection amplitude for which the described threshold of the deflection amplitude is used for example as a reference variable and the cycle rate for the working stroke can represent a control variable of the regulation.
Furthermore, the invention relates to a forming machine, in particular to a press. For example, such a forming facility can be a path-bound forming facility that can have, depending on the embodiment, a crank gear or a cam gear. In particular in the design of a press, the drive can comprise an electric motor that drives a flywheel that delivers the energy by means of a coupling device to the main gear, as described a crank gear or a cam gear. Exemplary forming devices are slider crank presses, eccentric presses and toggle presses. Moreover, the forming device according to the invention can also be a force-controlled forming machine, wherein the drive can be made available as a direct drive, for example either by an electric servomotor, also called torque motor, or comprises a hydrostatic drive for which the energy stored in the pressure medium is converted into mechanical energy by means of cylinders over a pump drive. In the nomenclature of this invention, a ram device that carries an upper tool of the machine is moved by the drive in case of force-controlled forming machines as well as of the path-bound forming machines.
The invention shall be explained below with the description of an embodiment and of modifications thereof with reference to the accompanying drawings.
In all the embodiments of such forming machines, a tumbling and/or tilting motion of the press 1 is generally generated during the clutch engaging for connecting the drive and the ram device or during the initiation of the working stroke and/or during the carrying out of the working stroke, for example because of an imbalance in the drive, due to the respective occurring of inertial forces or moments in inertia.
For force-controlled forming machines, these inertial forces or moments of inertia that excite a rigid body motion of the forming machine can be generated in particular by an imbalance in the drive and insofar occur during the entire time range of a working stroke of the ram device of the forming machine. For path-bound forming machines, these inertial forces or moments of inertia that excite a rigid body motion of the forming machine can occur in particular during the clutch engaging of the coupling located between the drive and the ram device or during the initiation of the working stroke. In such cases in which the drive experiences an imbalance, additional excitation torques or excitation forces can occur.
As explained, the press of
It is essential for carrying out the method according to the invention or the operation of the forming machine according to the invention that at least one kinematic variable of the rigid body motion, for example a deflection, of the elastically mounted forming machine 1 is detected during the operation thereof, is here measured by corresponding sensors as one or several motion sensors, wherein the time of the initiation of the working stroke, here the time for causing the operative connection between the drive and the ram device is adjusted in such a manner that the inertial forces and/or moments of inertia generated during the clutch engaging counteract the rigid body motion of the forming machine. In another embodiment, it can also be provided that the at least one kinematic variable of the rigid body motion, for example a deflection, is calculated by simulation of the rigid body motion of the forming machine, wherein an output signal of a motion sensor can be used for detecting the motion of the forming machine or another operating signal for the synchronization of the real motion of the forming machine with the simulation.
The method according to the invention for the phase-exact clutch engaging of the coupling of the press indicated in
In the described embodiment, the clutch engaging is adapted to a phase position of a kinematic variable, here a deflection of the forming machine from the rest position. The starting point of the method steps indicated in
In the method steps of
Exemplary courses of the rigid body motion of the forming machine of
The representations of
The curves of
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| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 120 012.9 | Jul 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/062445 | 5/11/2021 | WO |
