Focusing tube operational vibration as a means for monitoring the abrasive waterjet cutting capability

Copertaro, Edoardo; Perotti, F.; Castellini, Paolo; Chiariotti, Paolo; Martarelli, Milena; Annoni, Massimiliano

doi:10.1016/j.jmapro.2020.09.040

Cited by 18 publications

(26 citation statements)

References 19 publications

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“…The focuser is shown in Figure 13 and here the following features can be seen: two orthogonal flat areas, which have been machined on the external surface and nearby the tip, before sintering; two micro-accelerometers (DYTRAN 3224A), which have been attached to each flat area by means of LOCTITE 648; the technical specifications of the accelerometers are reported in Table 4. This same focuser was used by the authors in another investigation [25], which explains the reason for having two accelerometers onboard, despite only one has been used in the present study. As a first step, an impact test has been carried out on the focuser installed on the waterjet cutting machine, in order to verify the presence of a resonance at the frequency expected by the previous study: to the scope, two impact points have been considered, one at the tip of the focuser and the other on the clamp; the two impact points are indicated in Figure 8 with the "tip" and "top" labels, respectively; five strikes have been carried out, for each impact point; the vibration has been monitored by means of one of the two accelerometers; the acquisition parameters and computation methods have been maintained the same as for the previous impact tests.…”

Section: Inline Monitoring Of the Focuser First Mode Frequency During Operationmentioning

confidence: 94%

“…Due to its sensitivity to the wear progression, the first mode frequency is expected to gradually shift towards higher values, as operating hours are accumulated by the focuser; hence, this variable can be used as the indicator of its wear status. On this regard, the present focuser has been used in an analogous factorial study to the one discussed in [25], which overall involved 135 firings of the waterjet, each one of the duration of 30 s, and the acquisition of the correspondent accelerometer signal; the study equals to a total amount of about 4050 s of operation, which are not sufficient for bringing the focuser to a complete worn status, but could be sufficient for producing a detectable shift of the indicator. Indeed, the lower plot of Figure 16 shows the correspondent indicator computed for each one of the firings, and an upward trend is clearly exhibited; the red line is an interpolation of the experimental data points and indicates a total shift of the indicator of about 5 Hz by the end of the factorial study, with respect to its initial value; the statistical relevance of the trend is confirmed by the Mann-Kendall test [27], for a confidence level greater than 99 %.…”

Section: Inline Monitoring Of the Focuser First Mode Frequency During Operationmentioning

confidence: 99%

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Operational vibration of a waterjet focuser as means for monitoring its wear progression

Copertaro

Perotti

Annoni

2021

Int J Adv Manuf Technol

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Abrasive waterjet cutting is a competitive manufacturing technology in the aerospace, defense and automotive industries. End-user requirements are currently pushing machine builders to improve the automation of their processes, in an effort to reduce costs and downtimes, as well as increase robustness and stability. On this regard, the waterjet focuser is a critical component, as its fast wear progression requires constant human supervision, for promptly detecting detrimental effects on the cutting performance. This paper describes an innovative approach for in-line monitoring the wear progression of a waterjet focuser, by means of an accelerometer installed on its tip. This result is allowed by two separate studies of the focuser, of which the first investigates the sensitivity of its first mode frequency to the wear progression, whilst the second demonstrates the possibility of tracking said frequency from the in-line vibration signal delivered by the accelerometer, during operation. The presented setup makes use of low-cost sensing hardware that can be easily retrofitted into the design of waterjet focusers. The information delivered is expected to tackle end-user requirements for improved process automation.

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Section: Inline Monitoring Of the Focuser First Mode Frequency During Operationmentioning

confidence: 94%

Section: Inline Monitoring Of the Focuser First Mode Frequency During Operationmentioning

confidence: 99%

Operational vibration of a waterjet focuser as means for monitoring its wear progression

Copertaro

Perotti

Annoni

2021

Int J Adv Manuf Technol

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“…Recently, Pahuja and Ramulu [ 13 ] analysed the AE signals using wavelet packet transform (WPT) and proposed an algorithm to identify and characterize these signals. Copertaro et al [ 14 ] aimed at demonstrating that vibroacoustic sensors are the right choice for monitoring the AJW cutting capability; however, the investigation has been carried out with the cutting head in a steady position, while its movement was found to negatively affect the performance of the method. Therefore, it seems to serve rather as a calibration method.…”

Section: Introductionmentioning

confidence: 99%

Analyses of Vibration Signals Generated in W. Nr. 1.0038 Steel during Abrasive Water Jet Cutting Aimed to Process Control

Tyč

Hlaváčová

Barták³

2022

Materials

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The presented research was aimed at finding a suitable tool and procedure for monitoring undercuts or other problems such as cutting without abrasive or inappropriate parameters of the jet during the abrasive water jet (AWJ) cutting of hard-machined materials. Plates of structural steel RSt 37-2 of different thickness were cut through by AWJ with such traverse speeds that cuts of various qualities were obtained. Vibrations of the workpiece were monitored by three accelerometers mounted on the workpiece by a special block that was designed for this purpose. After detecting and recording vibration signals through the National Instruments (NI) program Signal Express, we processed this data by means of the LabVIEW Sound and Vibration Toolkit. Statistical evaluation of data was performed, and RMS was identified as the parameter most suitable for online vibration monitoring. We focus on the analysis of the relationship between the RMS and traverse speed.

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“…Copertaro et al [5] presented the idea of mounting the accelerator sensors (PCB 352C34 ICP ceramic) using a special adapter, in which two sensors were placed relative to each other at an angle of 90 degrees in the plane parallel to the surface of the workpiece and one sensor in the axis of the cutting head. It was noted that the relevant parameter which best represents the nature of the cut is the value of the recoil force acting in the axis of the cutter head.…”

Section: Introductionmentioning

confidence: 99%

“…Kovacevic et al [6] proved that in the low frequency range, the greatest influence on vibrations comes from the waterjet, while abrasive particles are responsible for vibrations above 10 kHz. In the research presented in [5], an index called the power index was determined, for which a strong linear correlation with the power of the waterjet was proven. This index helps to control stability by adjusting the pump pressure parameter and the abrasive flow rate.…”

Section: Introductionmentioning

confidence: 99%

Influence of Selected Diagnostic Parameters on the Quality of AWJ Cutting Surface

Wala¹,

Lis²

2022

Adv. Sci. Technol. Res. J.

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The article presents a review of research methods for the cutting process using the abrasive waterjet machining. The focus was on assessing the possibility of monitoring the cutting process based on the parameters available for direct or indirect measurement. An attempt was made to evaluate their infl uence on the machined surface after treatment with the abrasive cutting method. These parameters include, inter alia, vibrations of the cutting head, force eff ects on the head support structure and the material to be cut, dynamic properties of the machine support structure and high pressure pumps. As part of the own research, correlation was sought for the registered selected signal characteristics with the cutting parameters responsible for the process course and the parameters related to the obtained machined surface. For this purpose, a model of the defl ection angle of the abrasive waterjet was proposed, which qualitatively determines the condition of the surface after cutting. The angle of inclination of the abrasive waterjet is determined on the basis of the registration of the feed force during the cutting process. The research on surface topography was extended by an attempt to determine the surface roughness by measuring vibrations and looking for correlation between the displacements of the cutter head tip and the measured roughness height profi le. These tests also allowed the identifi cation of selected frequencies that clearly result from the set parameters of the cutting process. The last stage of the research was to monitor the cutter head behaviour using a deformation sensor as another concept for recording the forces during the cutting process. Finally, the proposed methodology was characterized in the context of its usefulness in the on-line process monitoring and supervision system.

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Focusing tube operational vibration as a means for monitoring the abrasive waterjet cutting capability

Cited by 18 publications

References 19 publications

Operational vibration of a waterjet focuser as means for monitoring its wear progression

Operational vibration of a waterjet focuser as means for monitoring its wear progression

Analyses of Vibration Signals Generated in W. Nr. 1.0038 Steel during Abrasive Water Jet Cutting Aimed to Process Control

Influence of Selected Diagnostic Parameters on the Quality of AWJ Cutting Surface

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