US-12617010-B2 - Bending method and bending machine for the execution of a bending method

US12617010B2US 12617010 B2US12617010 B2US 12617010B2US-12617010-B2

Abstract

A method of bending a metallic article comprising at least the following steps is described: a) executing a relative movement between a bending head having at least one bending group and the metallic article, and b) bending the metallic article by means of an activation of the bending group. During step b), at least a first actuation device actuates the bending group according to a respective motion profile and during the step a), at least a second actuation device actuates a relative movement between the bending head and the metallic article according to a respective motion profile. The method also comprises a step of preparing, during which a respective initial motion profile of the first actuation device and/or of the second actuation device is modified for obtaining the respective motion profile in function of a first parameter and of a second parameter.

Inventors

Fabrizio Caprotti
Andrea Baraldo
Angelo Ponti
Luca Bascetta
Gianni Ferretti

Assignees

BLM S.P.A.

Dates

Publication Date: 20260505
Application Date: 20211223
Priority Date: 20201223

Claims (18)

1 . A method of a bending machine adapted to bend a metallic article along a longitudinal axis, for obtaining a determined bended article comprising at least the following steps: executing a relative movement between a bending head of the bending machine, said bending head having at least one bending group, and the metallic article; and activating the at least one bending group to bend the metallic article; wherein during the activating of the at least one bending group, at least a first actuation device actuates the at least one bending group according to a respective first motion profile for executing a respective bending of the metallic article; wherein during the executing of the relative movement, at least a second actuation device actuates the relative movement between the bending head and the metallic article according to a respective second motion profile; wherein the method further comprises modifying, prior to an actuation of the at least one bending group by the first actuation device and an actuation of the relative movement by the second actuation device, a first initial motion profile of the first actuation device to obtain the respective first motion profile to be used during the actuation of the at least one bending group and a second initial motion profile of the second actuation device to obtain the respective second motion profile to be used during the actuation of the relative movement; wherein during the modifying of the first initial motion profile and the second initial motion profile, the first initial motion profile is modified in function of a first parameter and of a second parameter and the second initial motion profile is modified in function of a third parameter and a fourth parameter; wherein the first parameter depends on a first oscillation frequency of a first damped harmonic oscillator which models the oscillations of the metallic article resulting from the application of the respective first motion profile of the respective first actuation device and the second parameter depends on a first damping of the oscillations of the first damped harmonic oscillator; wherein the third parameter depends on a second oscillation frequency of a second damped harmonic oscillator which models the oscillations of the metallic article resulting from the application of the respective second motion profile of the respective second actuation device and the fourth parameter depends on a second damping of the oscillations of the second damped harmonic oscillator.
2 . The method according to claim 1 , comprising one or more steps of repeating, during which the executing of the relative movement and the activating of the at least one bending group are repeated; wherein during the modifying of the first initial motion profile and the second initial motion profile, a plurality of respective first initial motion profiles of the first actuation device are modified in function of the respective first parameters and the respective second parameters for obtaining the respective first motion profiles, and wherein during the modifying of the first initial motion profile and the second initial motion profile, a plurality of respective second initial motion profiles of the second actuation device are modified in function of the respective third parameters and the respective fourth parameters for obtaining the respective second motion profiles.
3 . The method according to claim 1 , wherein during the modifying of the first initial motion profile and the second initial motion profile, the first parameter, the second parameter, the third parameter, and the fourth parameter are read from a memory.
4 . The method according to claim 1 , further comprising a step of initialization, during which one or more first initial motion profiles and one or more second initial motion profiles are determined in function of the desired bended metallic article.
5 . The method according to claim 1 , further comprising a calibration step, during which the first parameter, the second parameter, the third parameter, the fourth parameter are determined; wherein during the calibration step the following sub-steps are executed: actuating the first initial motion profile; first monitoring the oscillations of the metallic article after the sub-step of actuating the first initial motion profile; and determining the first parameter and the second parameter of the damped harmonic oscillator which allow to describe first monitored oscillations during the respective sub-step of first monitoring; actuating the second initial motion profile; second monitoring the oscillations of the metallic article after the sub-step of actuating the second initial motion profile; and determining the third parameter and the fourth parameter of the damped harmonic oscillator which allow to describe second monitored oscillations during the respective sub-step of second monitoring.
6 . The method according to claim 5 , wherein during the sub-step of determining the first parameter and the second parameter, the first monitored oscillations are modelled according to a first damped harmonic oscillator being represented by means of a first transfer function G′(s) in the Laplace domain G′(s)=(b′*s+1)/(a′*s 2 +b′*s+1); with a′ corresponding to the first parameter to be determined and b′ corresponding to the second parameter to be determined; wherein during the sub-step of determining the third parameter and the fourth parameter, the second monitored oscillations are modelled according to a second damped harmonic oscillator being represented by means of a second transfer function G″(s) in the Laplace domain G″(s)=(b″*s′+1)/(a″*s′ 2 +b″*s′+1); with a″ corresponding to the third parameter to be determined and b″ corresponding to the fourth parameter to be determined.
7 . The method according to claim 6 , wherein during the sub-step of determining the first parameter and the second parameter, the following further steps are executed: i) assuming a value for the first parameter to be determined (a′) and a value for the second parameter to be determined (b′); ii) calculating estimated oscillations in function of the first transfer function (G′(s)) and the values for the first parameter to be determined (a′) and the second parameter to be determined (b′); iii) comparing the estimated oscillations with the first monitored oscillations for determining an error; iv) modifying the first parameter to be determined (a′) and the second parameter to be determined (b′) in function of the error obtained during the step iii); and v) repeating the steps i) to iv).
8 . The method according to claim 6 , wherein during the sub-step of determining third parameter and the fourth parameter, the following further steps are executed: i) assuming a value for the third parameter to be determined and a value for the fourth parameter to be determined; ii) calculating the estimated oscillations in function of the second transfer function and the values for the third parameter to be determined and the fourth parameter to be determined; iii) comparing the estimated oscillations with the second monitored oscillations for determining an error; iv) modifying the third parameter to be determined and the fourth parameter to be determined in function of the error obtained during the step iii); and v) repeating the steps i) to iv).
9 . The method according to claim 5 , wherein during the step of monitoring, the oscillations are monitored by means of a video camera.
10 . The method according to claim 1 , wherein the first parameter is proportional to the inverse of the square of the oscillation frequency and the second parameter is proportional to the damping and additionally is also proportional to the inverse of the oscillation frequency; and wherein the third parameter is proportional to the inverse of the square of the respective second oscillation frequency and the fourth parameter is proportional to the second damping and additionally is also proportional to the inverse of the second oscillation frequency.
11 . The method according to claim 1 , wherein the first damped harmonic oscillator is described by means of a first mass M, a first spring constant K and a first damping factor D; wherein the first oscillation frequency is proportional to √(K/M); and wherein the first damping is proportional to D/(2*√(M*K)); wherein the second damped harmonic oscillator is described by means of a second mass M, a second spring constant K and a second damping factor D; wherein the second oscillation frequency is proportional to √(K/M); and wherein the second damping is proportional to D/(2* √(M*K)).
12 . The method according to claim 1 , wherein a first transfer function in the Laplace domain of the first damped harmonic oscillator, which links the first motion profile to the oscillations is: G(s)=(b*s+1)/(a*s 2 +b*s+1); with a corresponding to the first parameter and b corresponding to the second parameter; wherein a second transfer function in the Laplace domain of the second damped harmonic oscillator, which links the second motion profile to the oscillations is: G(s)=(b′*s′+1)/(a′*s′ 2 +b′*s′+1); with a′ corresponding to the third parameter and b′ corresponding to the fourth parameter.
13 . The method according to claim 1 , wherein during the modifying of the first initial motion profile and the second initial motion profile, the first initial motion profile is filtered with a first transfer function expressed in the Laplace domain being proportional to (a*s 2 +b*s+1) for determining the first motion profile, with a corresponding to the first parameter and b corresponding to the second parameter; and wherein during the modifying of the first initial motion profile and the second initial motion profile, the second initial motion profile is filtered with a second transfer function expressed in the Laplace domain being proportional to (a′*s′ 2 +b′*s′+1) for determining the second motion profile, with a′ corresponding to the third parameter and b′ corresponding to the fourth parameter.
14 . The method according to claim 1 , wherein during the modifying of the first initial motion profile and the second initial motion profile, a first optimization sub-step is executed, during which the first motion profile which generates the oscillations when considering a first transfer function in the Laplace domain which is proportional to ((b*s+1)/(a*s 2 +b*s+1)) is determined; with a corresponding to the first parameter and b corresponding to the second parameter; and wherein during the modifying of the first initial motion profile and the second initial motion profile, a second optimization sub-step is executed, during which the second motion profile which generates the oscillations when considering a second transfer function in the Laplace domain which is proportional to ((b′*s′+1)/(a′*s′ 2 +b′*s′+1)) is determined; with a′ corresponding to the third parameter and b′ corresponding to the fourth parameter.
15 . The method according to claim 14 , wherein during the optimization sub-step, at the beginning of the optimization sub-step itself one applies a first motion profile obtained from a filtering of the first initial motion profile considering a first transfer function expressed in the Laplace domain being proportional to (a*s 2 +b*s+1), with a corresponding to the first parameter and b corresponding to the second parameter; and wherein during the optimization sub-step, at the beginning of the optimization sub-step itself one applies a second motion profile obtained from a filtering of the second initial motion profile considering a second transfer function expressed in the Laplace domain being proportional to (a′*s′ 2 +b′*s′+1), with a′ corresponding to the third parameter and b′ corresponding to the fourth parameter.
16 . The method according to claim 1 , wherein the metallic article is an elongated metallic article chosen from the group consisting of a metal wire and a metal tube.
17 . A bending machine for bending a metallic article, comprising: a control unit configured to control the operation of the bending machine itself; a bending head having at least one bending group configured to bend the metallic article; and an activation apparatus configured to activate a relative movement between the bending head and the metallic article; wherein the bending group comprises at least a first actuation device configured to actuate the at least one bending group according to a respective first motion profile for executing a respective bending of the metallic article; wherein the activation apparatus comprises at least a second actuation device configured to actuate the relative movement between the bending head and the metallic article according to a respective second motion profile; wherein the bending machine is configured to execute a step of modifying, prior to an actuation of the at least one bending group by the first actuation device and an actuation of the relative movement by the second actuation device, a first initial motion profile of the first actuation device to obtain the respective first motion profile to be used during the actuation of the at least one bending group and a second initial motion profile of the second actuation device to obtain the respective second motion profile to be used during the actuation of the relative movement; wherein the bending machine is configured to modify the first initial motion profile in function of a first parameter and of a second parameter and to modify the second initial motion profile in function of a third parameter and a fourth parameter; wherein the first parameter depends on a first oscillation frequency of a first damped harmonic oscillator which models the oscillations of the metallic article resulting from the application of the respective motion profile of the respective first actuation device and the second parameter depends on a damping of the oscillations of the damped harmonic oscillator; wherein the third parameter depends on a second oscillation frequency of a second damped harmonic oscillator which models the oscillations of the metallic article resulting from the application of the respective second motion profile of the respective second actuation device and the fourth parameter depends on a second damping of the oscillations of the second damped harmonic oscillator.
18 . The bending machine according to claim 17 , wherein the metallic article is an elongated metallic article chosen from the group consisting of a metal wire and a metal tube.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This Patent Application is a U.S. National Phase Application under 35 U.S.C. § 371 of International Patent Application No. PCT/IB2021/062268, filed on Dec. 23, 2021, which claims priority from Italian Patent Application No. 102020000032258, filed on Dec. 23, 2020, all of which are incorporated by reference, as if expressly set forth in their respective entireties. TECHNICAL FIELD The present invention relates to a method of bending a metallic article, in particular an elongated metallic article, even more in particular a metal wire or a metal tube, for obtaining a determined bended article. In particular, the present invention relates to a method of bending a metallic article which enables a reduction in the oscillations of the metallic article which may develop during the method itself. Advantageously, the present invention also relates to a bending machine, in particular a wire bending machine or tube bending machine, for the bending of metallic articles. BACKGROUND ART Bending machines are known for bending metal wires or for bending metal tubes. Such machines are configured to execute a series of bendings for obtaining a bended wire or a bended tube, respectively. It is also known that these machines comprise at least one bending head having one or more bending groups for carrying out the bendings and an activation apparatus for carrying out relative movements between the bending head and the wire or the tube. The activation apparatus allows to obtain a relative positioning between the wire or the tube and at least one of the bending groups so that said bending group can carry out a respective bending. It is known that the activation apparatus can be configured to move and/or rotate the bending head and/or advance the wire or tube along an advancement path. A typical bending group comprises a turret having one or more engagement elements, each configured to contact the wire or the tube and an actuator coupled to the turret and configured to rotate and translate the turret around and along an axis for bending the wire or the tube. During the bending, the respective actuator executes a respective determined motion profile so that at least one engagement element bends a portion of the wire or of the tube relative to another portion of the same wire or tube. Typically each wire or tube is subjected to a series of bendings for obtaining the respective desired bended wire or the respective desired bended tube. It is also known that for obtaining each bending the actuators must be controlled according to respective motion profiles and a respective sequence of motion profiles must also be applied in combination with modifications of the relative position between the bending head and the wire or the tube. It has been observed that oscillations of the wire or of the tube may develop during the method which can sometimes result in unwanted deformations of the wire or tube and/or in the collision of the wire or of the tube with parts of the bending machine. In order to avoid these problems, an operator must manually modify the specific bending method consisting of steps of bending and steps of modification of the relative position between the bending head and the wire or the tube. On the one hand, such modifications require a significant amount of time, and on the other hand, the modifications and their success rely on the experience and expertise of the specific operator. Furthermore, it should be considered that the application of such modifications requires not only a high level of experience of the operator, but also a high basic qualification. These aspects can be problematic in countries where there is a shortage of skilled workers. In addition, a drawback may develop in contexts in which there is a high turnover of operators. Furthermore, US-A-2011192204 proposes to reduce the oscillations thanks to the generation of compensation movements. In alternative, DE-A-102014206622 describes the use of simulations, which require significant computational resources, for optimizing the bending of articles to be bend. There is therefore a need in the industry for a further improvement of the methods of bending and/or of the bending machines which will allow to solve at least one of the known drawbacks. In particular, there is a need in the industry for a method of bending and/or for a bending machine that allows a reduction in the oscillations of the wire or of the tube in an automated way. DISCLOSURE OF INVENTION The aforesaid aims are achieved by the present invention, since it relates to a method of bending a metallic article as defined in the independent claim. Alternative preferred embodiments are protected in the respective dependent claims. The aforesaid aims are also achieved by the present invention, since it relates to a machine according to claim 15. BRIEF DESCRIPTION OF THE DRAWINGS Further features and advantages of the present invention will become apparent from the