Ultrasound scan under load

Abstract

A method for operating an ultrasonic system under load at startup includes: performing a scan of the impedance and phase of an ultrasonic stack under operating load, determining from the scan which resonance under load and which phase this resonance is, and, during contact with a workpiece under load at startup, operating the ultrasonic stack with the determined resonance and phase.

Description

AREA

[0001] The present disclosure relates to an ultrasound scan under load. BACKGROUND

[0002] This section provides background information relating to the present disclosure and does not necessarily represent the state of the art.

[0003] An ultrasonic power supply that starts with its ultrasonic stack under load will have a different starting frequency than when the ultrasonic stack is in air. Often, the operating frequency of the ultrasonic stack in air is known, as it is designed to exhibit a specific resonance in air. Ultrasonic power supplies are traditionally designed to have a standard starting frequency for the stack in air. If the power supply attempts to start with the stack under load, the frequency shift often results in an overload of the power supply. Traditionally, many ultrasonic power supplies had the ability to manually adjust the starting frequency, but this is an imprecise and non-automatic procedure. SUMMARY

[0004] This section provides a general summary of the revelation and is not a detailed revelation of its entire scope or all of its features.

[0005] A method for operating an ultrasonic system under load during startup includes: performing a scan of the impedance and phase of an ultrasonic stack under operating load, determining from the scan what the resonance is under load and what phase this resonance is, and, during contact with a workpiece under load during startup, operating the ultrasonic stack with the determined resonance and phase.

[0006] A method for operating an ultrasonic system under load during startup, comprising: Performing an impedance and phase scan of an ultrasound stack under various operating loads; Determine, based on the scan, what resonance occurs under a specific load and what phase this resonance is; and during contact with a workpiece under the specified load when starting, operating the ultrasonic stack with the specified resonance and phase.

[0007] According to another aspect, a target phase of a control loop for an ultrasound device is changed when a load of the ultrasound system changes.

[0008] According to another aspect, the specific load at startup is determined by a load sensor that detects a load exerted on the workpiece by the ultrasonic stack.

[0009] According to another aspect, if the load detected by the load sensor changes during a welding process, the resonance and phase of the ultrasonic stack will change according to the load detected by the load sensor.

[0010] According to another aspect, an actuator carries the ultrasonic stack and the actuator is controlled by a controller so that it exerts a load on the ultrasonic stack against the workpiece.

[0011] According to another aspect, the specific operating load is predetermined at startup.

[0012] According to another aspect, the ultrasound stack includes a converter and a sonotrode.

[0013] From another perspective, an ultrasonic system includes an ultrasonic power supply. An ultrasonic stack is connected to the ultrasonic power supply. An actuator is configured to support the ultrasonic stack and to press the ultrasonic stack against a workpiece under load. A controller operates the actuator so that it applies a load to the ultrasonic stack against a workpiece upon startup and also powers the ultrasonic supply at startup according to a stored resonance and phase for the load applied to the workpiece.

[0014] According to another aspect, the controller has a memory that stores scanned resonance and phase data for the ultrasonic system under various operating loads, and when the ultrasonic batch is started, the controller determines a resonance and phase from the memory to operate the ultrasonic power supply according to the corresponding load applied to the workpiece.

[0015] According to another aspect, a load sensor detects a load exerted on the workpiece by the ultrasonic stack.

[0016] According to another aspect, the controller receives a load signal from the load sensor and activates the ultrasonic stack with a resonance and phase at startup that correspond to the load signal. The resonance and phase can be stored or interpolated values ​​that correspond to the load signal.

[0017] According to another aspect, the load exerted on the workpiece is predetermined by the control system.

[0018] According to another aspect, the ultrasound stack includes a converter and a sonotrode.

[0019] Further areas of application are evident from the description provided here. The description and specific examples in this summary serve only for illustrative purposes and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described here serve to illustrate only selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. Fig. Figure 1 is a schematic view of an exemplary ultrasonic welding device according to the principles of the present disclosure; Fig. Figure 2 is a diagram of impedance and phase to frequency, where the ultrasound stack is not in contact or is in a non-contact state; Fig. 3A and Fig. Figure 3B shows diagrams of impedance and phase versus frequency, with the ultrasonic stack subjected to different contact load levels; Fig. Figure 4 is a diagram of impedance and phase versus frequency, with the ultrasonic stack under actuation load; and Fig. Figure 5 shows a diagram of impedance and phase under different actuation loads.

[0021] Corresponding reference symbols point to corresponding parts in all different views of the figures. DETAILED DESCRIPTION

[0022] Exemplary embodiments are now described in more detail with reference to the accompanying drawings.

[0023] An ultrasound system 10 typically consists of an ultrasound power supply 12, an ultrasound stack 14, and an actuator 16, as shown in Fig. Figure 1 shows the ultrasonic stack 14, which typically includes an ultrasonic converter 18 that converts the electrical energy from the power supply 12 into ultrasonic motion, an amplifier or booster 20 that amplifies the ultrasonic motion, and a sonotrode 22 that performs the actual work on the workpiece 24. The actuator 16 moves the ultrasonic stack 14 relative to the workpiece 24 so that the tip 26 of the sonotrode 22 touches the workpiece 24.

[0024] The stack 14 can comprise only one converter 18 and one sonotrode 22, or one converter 18, one booster 20, and one sonotrode 22. The stack 14 can be a linear stack, a rotary stack, a compound stack, a cross-sonotrode stack, or any combination thereof. In other words, the stack can be anything driven by a converter. The ultrasonic system can be used for any type of ultrasonic process, such as welding, stacking, die forging, sonotrode / sonification, cleaning, cutting, etc., but is not limited to these.

[0025] An ultrasonic stack 14 operates best when operated either at series resonance, when the impedance is at a minimum, or at parallel resonance, when the impedance is at a maximum. When the ultrasonic stack 14 is under no load, such as in air, resonance occurs when the phase between the current waveform and the voltage waveform is approximately zero, as is the case in Fig. 2 is shown. However, when the ultrasonic stack 14 comes into contact with a semi-rigid load / workpiece, the resonant frequency shifts, as also shown in Fig. Figure 3A shows that the higher the load, the greater the increase in the frequency of the parallel and series resonances, although the overall impedance curve tends to be compressed. As shown in Fig. As shown in Figure 3B, the phase is no longer zero at either resonance.

[0026] An ultrasonic power supply 12 that starts with its ultrasonic stack 14 under load has a different starting frequency than when the ultrasonic stack 14 is in the air. Often, the operating frequency of the ultrasonic stack 14 in the air is known because it is designed to exhibit a specific resonance in air. Ultrasonic power supplies are traditionally designed to have a standard starting frequency for the stack 14 in the air. If the power supply 12 attempts to start with the stack 14 under load, the frequency shift often leads to an overload of the power supply 12. Traditionally, many ultrasonic power supplies had the ability to manually adjust the starting frequency; however, this is an imprecise and not an automatic procedure.

[0027] In addition, the ideal operating point of the ultrasonic power supply 12 lies at the series or parallel resonance of the stack. In air, this corresponds to a phase between current and voltage of approximately zero. However, when the stack 14 is under load, the phase corresponding to the series or parallel resonance falls below zero, as shown in Fig. Figure 3B shows that ultrasonic power supplies are traditionally operated at the zero phase or at some set value of the negative phase. This is not ideal and can lead to overload.

[0028] The present disclosure solves these two problems by performing a scan of impedance and phase while the stack 14 is at full operating load, increased or reduced power, reading where the resonance is located (either series or parallel) and what phase that resonance is, and using that frequency to start the ultrasound at full power and that phase to perform or operate the ultrasound under load. For example, with reference to the Fig. 3A and Fig. 3B the control 12, by entering a contact load pressure of the ultrasonic device at startup, select an impedance and phase to operate the ultrasonic device at startup.

[0029] Similarly, under dynamic, variable stack load conditions, such as in a continuous textile line, variations in load can lead to overloads of the ultrasonic power supply 12 during operation. The present disclosure solves this third problem by performing a family of scans for impedance and phase under different loads of the stack 14 at full, increased, or reduced power, then, while the stack 14 is running at full power and the force signal 28 is read from the actuator 16, using the appropriate phase of the resonance under load and adjusting the phase to the changing load.

[0030] The present disclosure measures the phase and impedance under different loads by having the power supply 12 perform a phase and impedance scan under various loads. The scan operates the power supply 12 in a frequency sweep and measures the phase and impedance while the actuator 16 applies a load to the workpiece 24 being worked on. The scans can be stored in a memory 32 of the power supply 12. The series and parallel resonances are calculated by a controller 30 and / or a processor 34 of the power supply 12, and their associated phases are calculated.

[0031] There are two methods for calculating series and parallel resonances. Referring to Fig. 4. The first method to find the series resonance is to record the frequency where the impedance is at its minimum. The first method to find the parallel resonance is to record the frequency where the impedance is at its maximum. The first method to find the corresponding phases is to read the phases at the found maximum and minimum impedances. The second method to find the two resonances is to measure the peak phase of the frequency sweep. Both resonances are approximately at a phase that corresponds to the midpoint between the peak phase and the -90-degree phase. At this value, the series resonance is at the lower frequency of the phase, and the parallel resonance is at the higher frequency of the phase.The second method has the advantage that only the phase during the pass needs to be measured, and this is more accurate because impedance curves tend to be compressed under load, which can make it difficult to pinpoint the peaks and troughs accurately.

[0032] When power supply 12 starts under actuator load, it uses the resonant frequency determined or interpolated from load scans. This prevents overloads caused by starting power supply 12 outside of resonant frequency, which would otherwise occur if power supply 12 used resonant frequency when starting stack 14 in mid-air. An overload condition exists when the voltage and / or current supplied to the converter exceeds what is safe for the power supply components. Typically, a safety circuit in power supply 12 shuts down the power supply 12 when this condition occurs to protect the components.

[0033] During operation of the power supply 12, resonance is maintained by controlling the phase between the current and voltage of the power supply 12. The target phase used for the power supply 12 when the stack is under load is determined or interpolated from the load scans. This prevents overloads. In the prior art, zero phase or an arbitrary fixed negative phase was used, neither of which accurately represents the phase at resonance under load and therefore could more easily cause overloads.

[0034] For applications requiring variable loads during operation, such as a textile production line, scans are performed at various load levels prior to operation. The family or group of impedance and phase curves is used to interpolate the resonance and phase at each given load. An actuator force signal 28 communicates with the power supply controller 30 12 during operation, providing the variable load state information. The appropriate phase from the interpolation is used for the given load at each given time and changes with the changing load states. This prevents overloads caused by varying load states.

[0035] Power supply 12 can operate in either parallel or series resonance. If power supply 12 operates in series resonance, only the series resonance needs to be calculated by scanning under load. If power supply 12 operates in parallel resonance, only the parallel resonance needs to be calculated.

[0036] The present disclosure can be used for only the starting frequency under load, in which case the phase under load does not need to be known.

[0037] The impedance (Z) represents the resistance that an ultrasonic welding system offers to the flow of alternating current (AC) due to the combined effects of resistance, capacitance, and inductance. During the joining cycle, as the two surfaces come into contact and the joint size increases, the impedance changes. It increases as the joint forms. In constant-current operation, the output of the ultrasonic generator maintains a constant current. When the impedance changes, the current remains constant, resulting in an increase in voltage (V) to maintain a constant displacement of the tool tip.

[0038] With reference to Fig.Figure 5 shows a diagram or graph of impedance and phase versus frequency, illustrating different amplitudes under varying loads. According to the principles of this disclosure, the amplitude for operation can be controlled during startup under different loads. An actuator force signal 28 communicates with the control unit 30 of the power supply 12 during operation and provides information on the variable load conditions. The appropriate amplitude from the interpolation is used for the given load at any given time and changes with changes in the load conditions. This prevents overloads caused by varying load conditions.

[0039] The present disclosure can be used for operation under a constant load only, in which case the starting frequency under load need not be known and only one phase under load needs to be known. The present disclosure can also be used for operation under a variable load only, in which case the starting frequency under load does not need to be known, but the family or group of phases to load must be known. The present disclosure can also be used with any combination of the above.

[0040] Exemplary embodiments are provided so that this disclosure is comprehensive and will fully convey its scope to the person skilled in the art. Numerous specific details are set forth, such as examples of certain components, devices, and processes, to provide a complete understanding of the embodiments of this disclosure. It will be clear to the person skilled in the art that certain details need not be implemented, that exemplary embodiments can be carried out in many different ways, and that nothing should be understood as limiting the scope of the disclosure. In some exemplary embodiments, known processes, known device structures, and known technologies are not described in detail.

[0041] The terminology used here serves only to describe certain exemplary embodiments and is not intended to be restrictive. The singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprise," "comprehensive," "including," and "exhibiting" are inclusive terms and therefore indicate the presence of mentioned features, numbers, steps, processes, elements, and / or components, but do not exclude the presence or addition of one or more features, numbers, steps, processes, elements, components, and / or groups thereof. The procedural steps, processes, and operations described here are not to be understood as necessarily being dependent on the specific sequence discussed or presented, unless this is specifically stated as the execution sequence.It goes without saying that additional or alternative steps can be taken.

[0042] When an element or layer is referred to as "on," "interacting with," "connected with," or "coupled with" another element or layer, it may be directly on, interacting with, connected with, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly interacting with," "directly connected with," or "directly coupled to" another element or layer, there may be no intervening element or layer. Other expressions used to describe the relationship between elements should be understood similarly (e.g., "between" to "directly between," "adjacent" to "directly adjacent," etc.). The terms "and / or" used here include any combination of one or more of the related, enumerated parts.

[0043] Although the terms first, second, third, etc., may be used here to describe different elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections are not intended to be restricted by these terms. These terms may also be used simply to distinguish one element, component, region, layer, or section from another. Terms such as "first," "second," or other numerical terms as used herein do not imply any sequence or order unless clearly indicated by the context. Therefore, a first element, component, region, layer, or section discussed below could be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0044] Spatially related terms such as "inside," "outside," "below," "under," "lower," "above / above," "upper," and the like may be used here to simplify the description and describe the relationship of one element or feature to another, as shown in the figures. Spatially related terms can be understood to encompass different orientations of the device during use or operation, in addition to the orientation shown in the figures. For example, if the device in the figures is turned upside down, elements described as "below" or "underneath" other elements or features would then be oriented "above" them. Therefore, the exemplary term "below" can encompass both an orientation above and below.The device may be oriented differently (rotated by 90° or in other orientations) and the spatially related describers used here are interpreted accordingly.

[0045] The foregoing description of the embodiments serves for illustrative and descriptive purposes. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are not, in principle, limited to that particular embodiment, but are interchangeable where applicable and may be used in a selected embodiment, even if this is not explicitly shown or described. Many different variations may also be made. These variations are not to be regarded as a departure from the disclosure, and all such modifications are to be considered to be within the scope of the disclosure.

Claims

[1] A method for operating an ultrasonic system under load during start-up, comprising: Performing impedance and phase scans of an ultrasound stack under various operating loads; Determine, based on the scan, what resonance occurs under a specific load and what phase this resonance is; and during contact with a workpiece under the specified load when starting, operating the ultrasonic stack with the specified resonance and phase. [2] The method of operating an ultrasound system under load during start-up according to claim 1, further comprising changing a target phase of a control loop for an ultrasound device when a load of the ultrasound system changes. [3] The method of operating an ultrasonic system under load at start-up according to claim 1, wherein the specified load at start-up is determined by a load sensor which detects a load exerted on the workpiece by the ultrasonic stack, and the impedance and phase are interpolated from the scans. [4] The method of operating an ultrasonic system under load during start-up according to claim 3, wherein when the load detected by the load sensor changes during a welding process, the resonance and phase of the ultrasonic stack is changed according to the load detected by the load sensor. [5] The method of operating an ultrasonic system under load at start-up according to claim 1, wherein an actuator carries the ultrasonic stack and the actuator is controlled by a controller to exert a load on the ultrasonic stack against the workpiece. [6] The method of operating an ultrasonic system under load during start-up according to claim 1, wherein the specific operating load is predetermined during start-up. [7] The method of operating an ultrasonic system under load during start-up according to claim 1, wherein the ultrasonic stack comprises a converter and a sonotrode. [8] A method for operating an ultrasonic system under load during start-up, comprising: Performing scans of the amplitude of an ultrasound stack under various operating loads; Determining an operating load of the ultrasonic system against a workpiece; Determine the amplitude under the specified operating load based on the scan; and during contact with a workpiece under operating load at startup, operation of the ultrasonic stack at the specified amplitude. [9] The method of operating an ultrasound system under load according to claim 8, further comprising changing a target phase of a control loop for an ultrasound device when a load of the ultrasound system changes. [10] The method of operating an ultrasonic system under load according to claim 8, wherein the specified load is determined at start-up by a load sensor which detects a load exerted on the workpiece by the ultrasonic stack and the amplitude is interpolated from the scans. [11] The method of operating an ultrasonic system under load according to claim 10, wherein when the load detected by the load sensor changes during a welding process, the resonance and phase of the ultrasonic stack is changed according to the load detected by the load sensor. [12] The method of operating an ultrasonic system under load according to claim 8, wherein an actuator carries the ultrasonic stack and the actuator is controlled by a controller to exert a load on the ultrasonic stack against the workpiece. [13] The method of operating an ultrasonic system under load according to claim 8, wherein the specific operating load is predetermined at startup. [14] The method of operating an ultrasound system under load according to claim 8, wherein the ultrasound stack comprises a converter and a sonotrode. [15] An ultrasound system comprising: an ultrasonic power supply; an ultrasonic stack connected to the ultrasonic power supply; an actuator configured to movably support the ultrasonic stack, and configured to press the ultrasonic stack against a workpiece under load; and a control system for operating the actuator to apply a load to the ultrasonic stack against a workpiece at startup, and for operating the ultrasonic power supply at startup according to a stored resonance and phase for the load applied to the workpiece. [16] The ultrasonic system according to claim 15, wherein the controller has a memory that stores scanned resonance and phase data for the ultrasonic system at various operating loads, and when starting the ultrasonic batch, the controller determines a resonance and phase from the memory to operate the ultrasonic power supply according to the corresponding load applied to the workpiece. [17] The ultrasonic system according to claim 15, further comprising a load sensor for detecting a load exerted on the workpiece by the ultrasonic stack. [18] The ultrasonic system according to claim 17, wherein the controller receives a load signal from the load sensor and activates the ultrasonic stack with a stored resonance and phase at startup that corresponds to the load signal. [19] The ultrasonic system according to claim 15, wherein the load applied to the workpiece is predetermined. [20] The ultrasound system according to claim 15, wherein the ultrasound stack comprises a converter and a sonotrode.

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