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3 pages, 193 KiB

Open AccessEditorial

Editorial for Special Issue “Advances in Computer-Aided Technology”

by Martin Pollák and Marek Kočiško

Machines 2023, 11(2), 227; https://doi.org/10.3390/machines11020227 - 3 Feb 2023

Viewed by 1019

Abstract

The determination of this Special Issue topic, in the field of Advances in Computer-Aided Technology belonging to the section “Mechatronic and Intelligent Machines”, was well received by the community of scientists and researchers [...] Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

Research

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15 pages, 4262 KiB

Open AccessArticle

Dynamic Modeling of a Hydraulic Excavator Stick by Introducing Multi-Case Synthesized Load Spectrum for Bench Fatigue Test

by Penghui Wang, Qingyi Xiang, Grzegorz Królczyk, Pengmin Lu, Binhua Wang and Zhixiong Li

Machines 2022, 10(9), 741; https://doi.org/10.3390/machines10090741 - 28 Aug 2022

Cited by 3 | Viewed by 1815

Abstract

A multi-case load spectrum compiling method is proposed in this study for dynamic modeling of a hydraulic excavator stick to simplify and accelerate the fatigue bench test. This new method includes a simplified criterion of small-load-omitting threshold based on the principle of invariable [...] Read more.

A multi-case load spectrum compiling method is proposed in this study for dynamic modeling of a hydraulic excavator stick to simplify and accelerate the fatigue bench test. This new method includes a simplified criterion of small-load-omitting threshold based on the principle of invariable fatigue damage, an extreme value inference criterion based on the overflow characteristics of the hydraulic system, and a synthetic extrapolation method under various working conditions. Firstly, a one-dimensional spectrum of a medium-sized excavator stick was compiled. Then, the program load spectrum for the bench fatigue test was obtained by modifying the one-dimensional spectrum based on the damage consistency criterion and the damage equivalent principle. Lastly, the fatigue tests were conducted using the program load spectrum, as well as using the random spectrum. The comparison results demonstrate that the damage location and fatigue life distribution of the stick using these two spectra are generally consistent, with a relative error smaller than 8.8%; however, the proposed program load spectrum can accelerate the test process with less time consuming than that of the random spectrum. As a result, the multi-case load spectrum is feasible and reliable for dynamic modeling of the hydraulic excavator stick in practice. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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18 pages, 7348 KiB

Open AccessArticle

Modified Drive Structure of a Knitting Machine

by Josef Skrivanek, Martin Bilek and Ondrej Batka

Machines 2022, 10(8), 615; https://doi.org/10.3390/machines10080615 - 27 Jul 2022

Cited by 3 | Viewed by 3020

Abstract

This paper deals with the problematic of the drive system of small-diameter knitting machines (hereinafter “knitting machines”). An alternative design of a new drive system is presented that addresses the effective working position of selected operating elements, i.e., a cylinder, a dial, and [...] Read more.

This paper deals with the problematic of the drive system of small-diameter knitting machines (hereinafter “knitting machines”). An alternative design of a new drive system is presented that addresses the effective working position of selected operating elements, i.e., a cylinder, a dial, and a roller cutter. The design is protected by patent No. 303578, and the authors of this paper also authored the patent. For the description and simulation of the drive system, mathematical models have been elaborated of the existing and new drive system, which include an additional design of a more suitable stroke for the movement of the cylinder. The output of the simulations are the courses of kinematic quantities, torque, and electric current, elucidating the benefits of the new drive system. Based on the structure of the new drive system, a test device has been designed and manufactured to verify functionality and reliability. The new drive system consumes less energy, simplifies the machine frame and reduces noise emissions. The obtained results can help in researching the issue of knitting machine frames, and in addition, the new system brings new technological possibilities for knitting. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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12 pages, 11966 KiB

Open AccessArticle

Machining of Wood Plastic Composite Using AWJ Technology with Controlled Output Quality

by Zuzana Mitaľová, František Botko, Radoslav Vandžura, Juliána Litecká, Dušan Mitaľ and Vladimír Simkulet

Machines 2022, 10(7), 566; https://doi.org/10.3390/machines10070566 - 14 Jul 2022

Cited by 6 | Viewed by 2120

Abstract

The paper deals with the application of abrasive water-jet cutting to composite material containing natural reinforcement—wood plastic composite. The specimens were cut through the application of four flows of different abrasive mass: 150, 200, 250, and 300 g·min⁻¹, respectively, and under [...] Read more.

The paper deals with the application of abrasive water-jet cutting to composite material containing natural reinforcement—wood plastic composite. The specimens were cut through the application of four flows of different abrasive mass: 150, 200, 250, and 300 g·min⁻¹, respectively, and under different traverse speeds required to achieve the (expected) quality level Q1–Q5 (according to the SN 214001: 2010 standard). The output quality of Q1–Q5 was set in the CNC cutting programs and the real traverse speed values were calculated by machine control system according to change in the flow of the abrasive mass. The quality of surface topography was assessed using a tester (contact roughness) and an Inspectis digital zoom microscope. The results of topography–surface roughness parameters Ra presented here are compared with the values normalized for individual samples sets. The applied technology, i.e., the AWJ, eliminated the problem of tool wear and adhesion of the thermoplastic matrix to tool surfaces (compared to standard machining). Full article

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17 pages, 4258 KiB

Open AccessEditor’s ChoiceArticle

Online Monitoring of Surface Quality for Diagnostic Features in 3D Printing

by Natalia Lishchenko, Ján Piteľ and Vasily Larshin

Machines 2022, 10(7), 541; https://doi.org/10.3390/machines10070541 - 4 Jul 2022

Cited by 14 | Viewed by 3734

Abstract

Investigation into non-destructive testing and evaluation of 3D printing quality is relevant due to the lack of reliable methods for non-destructive testing of 3D printing defects, including testing of the surface quality of 3D printed parts. The article shows how it is possible [...] Read more.

Investigation into non-destructive testing and evaluation of 3D printing quality is relevant due to the lack of reliable methods for non-destructive testing of 3D printing defects, including testing of the surface quality of 3D printed parts. The article shows how it is possible to increase the efficiency of online monitoring of the quality of the 3D printing technological process through the use of an optical contactless high-performance measuring instrument. A comparative study of contact (R130 roughness tester) and non-contact (LJ-8020 laser profiler) methods for determining the height of irregularities on the surface of a steel reference specimen was performed. It was found that, in the range of operation of the contact method (Ra 0.03–6.3 µm and Rz 0.2–18.5 µm), the errors of the contactless method in determining the standard surface roughness indicators Ra and Rz were 23.7% and 1.6%, respectively. Similar comparative studies of contact and non-contact methods were performed with three defect-free samples made of plastic polylactic acid (PLA), with surface irregularities within the specified range of operation of the contact method. The corresponding errors increased and amounted to 65.96% and 76.32%. Finally, investigations were carried out using only the non-contact method for samples with different types of 3D printing defects. It was found that the following power spectral density (PSD) estimates can be used as diagnostic features for determining 3D printing defects: Variance and Median. These generalized estimates are the most sensitive to 3D printing defects and can be used as diagnostic features in online monitoring of object surface quality in 3D printing. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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13 pages, 2223 KiB

Open AccessArticle

Development of Flexible Fixtures with Incomplete Locating: Connecting Rods Machining Case Study

by Vitalii Ivanov, František Botko, Ivan Dehtiarov, Marek Kočiško, Artem Evtuhov, Ivan Pavlenko and Justyna Trojanowska

Machines 2022, 10(7), 493; https://doi.org/10.3390/machines10070493 - 21 Jun 2022

Cited by 13 | Viewed by 3674

Abstract

The rapid development of manufacturing in recent years has led to a significant expansion of the technological capabilities of modern metal-cutting equipment. Therefore, the modern approach to intensifying production requires an advanced fixture design. Design and manufacture of flexible fixtures capable of machining [...] Read more.

The rapid development of manufacturing in recent years has led to a significant expansion of the technological capabilities of modern metal-cutting equipment. Therefore, the modern approach to intensifying production requires an advanced fixture design. Design and manufacture of flexible fixtures capable of machining similar shapes and sizes of complex geometry parts reduce setup time. The article aims to design flexible fixtures for parts such as one-piece connecting rods under incomplete locating conditions. The advantages are the minimum number of parts and tool availability for multi-axis machining connecting rods in one setup. This approach, combined with up-to-date machining centers and industrial robots, can increase the production efficiency of manufacturing non-removable connecting rods. This effectiveness is in a decrease in the number of operations by 5–7 times, fixtures—by 3–4 times, and machine tools—by 3–5 times, depending on the type of a non-removable connecting rod and its design features. The numerical simulation results of the proposed fixture design confirmed the comprehensive technological capabilities and dynamic characteristics. Particularly, a decrease in displacements and oscillation amplitudes up to 7% compared to the full-basing locating chart was provided. It is determined that the system “fixture–workpiece” entirely meets all the strength, accuracy, and rigidity parameters, which allows you to perform machining with intensive cutting modes. The amplitudes of oscillations do not exceed the tolerances on the dimensions of these surfaces, established by requirements for non-removable connecting rods, and all displacements are elastic. During numerical simulation, the workpiece position remained stable at all machining steps. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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13 pages, 2099 KiB

Open AccessArticle

Measurement and Modelling of a Cycloidal Gearbox in Actuator with Permanent Magnet Synchronous Machine

by Viktor Šlapák, Jozef Ivan, Karol Kyslan, Matúš Hric, František Ďurovský, Dušan Paulišin and Marek Kočiško

Machines 2022, 10(5), 344; https://doi.org/10.3390/machines10050344 - 7 May 2022

Cited by 4 | Viewed by 2822

Abstract

Compact geared servo drives are a common part of modern industrial automation; thus, their proper modelling is a necessary part for the application and control design. The presented paper focuses on the mathematical model of the cycloidal gearbox, which is used in the [...] Read more.

Compact geared servo drives are a common part of modern industrial automation; thus, their proper modelling is a necessary part for the application and control design. The presented paper focuses on the mathematical model of the cycloidal gearbox, which is used in the compact actuator with a permanent magnet synchronous motor. A measurement procedure to obtain the necessary gearbox parameters is presented along with its mathematical model. A new approach was used to model the stiction and nonlinear gearbox friction behaviour in all four quadrants. A simulation of the actuator with the modelled gearbox is described and its results are compared with the real system measurement. Obtained results show a high match between simulation and experimental results and confirm the correctness of the simulation model. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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19 pages, 8007 KiB

Open AccessEditor’s ChoiceArticle

Design of Electromagnetic Control of the Needle Gripping Mechanism

by Jiří Komárek and Vojtěch Klogner

Machines 2022, 10(5), 309; https://doi.org/10.3390/machines10050309 - 26 Apr 2022

Cited by 4 | Viewed by 2828

Abstract

This paper deals with the modification of the mechanical system of the needle bar. The purpose of this work is to reduce the vibration and noise of the sewing machine for creating a decorative stitch. A special floating needle is used to sew [...] Read more.

This paper deals with the modification of the mechanical system of the needle bar. The purpose of this work is to reduce the vibration and noise of the sewing machine for creating a decorative stitch. A special floating needle is used to sew this stitch, in which two mechanical systems of needle bars handover through the sewn material, so that a perfect imitation of a hand stitch is created. The original system, which controls the release of the needle at the handover location by abruptly stopping the needle bar control element, could be replaced by a new system that uses magnetic force to release the needle. In addition to the usual design procedure, numerical simulations of the attractive force of the electromagnet are also used in the design of a suitable electromagnet. At the same time, an electrical circuit is also designed to allow the needle to be released and gripped quickly. The advantages of the new system lie not only in reducing vibrations and the associated increase in the operation speed of the machine, but also in making it easier for the machine to switch to possible automated or semi-automated production. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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12 pages, 1976 KiB

Open AccessArticle

Assessing the Effect of Interimplant Distance and Angle on Different Impression Techniques

by Berkman Albayrak, İsmail Hakkı Korkmaz, Alvin G. Wee, Cortino Sukotjo and Funda Bayındır

Machines 2022, 10(5), 293; https://doi.org/10.3390/machines10050293 - 21 Apr 2022

Cited by 2 | Viewed by 2065

Abstract

We aimed to evaluate the trueness of digital and conventional impression techniques based on different angles and distances between implants and the deviation caused by the angle and distance parameters varying between implants. Eight implants were placed in a polyurethane edentulous mandibular model [...] Read more.

We aimed to evaluate the trueness of digital and conventional impression techniques based on different angles and distances between implants and the deviation caused by the angle and distance parameters varying between implants. Eight implants were placed in a polyurethane edentulous mandibular model at different angles and distances. After obtaining a 3-dimensional (3D) reference model by using an optical scanner, the model was scanned with three intraoral scanners: Cerec Omnicam (DO), Trios 3 (DT), and Carestream 3500 (DC). Then, the master casts obtained from the conventional impressions (C) were also digitized, and all impression data were imported into reverse engineering software to be compared with the 3D reference model. Distance and angle measurements between adjacent implants were performed, and the data were analyzed with ANOVA–Tukey and Kruskal Wallis tests. The significance level was accepted as p < 0.05. While DT and C groups gave the best results for high interimplant distances, the trueness of intraoral scanners was found to be superior to the conventional method between closer implants. At higher angulations, the angular trueness of C group was found to be significantly lower. At short distances, digital groups showed superiority, and the trueness of conventional impression decreased with higher angulations. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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20 pages, 8192 KiB

Open AccessArticle

Research into the Impact of Spindle Speed and Feed Rate Changes on the Life of a Deep-Drilling Technology Tool

by Martin Pollák, Marek Kočiško, Jaroslav Petrus, Sorin Dumitru Grozav and Vasile Ceclan

Machines 2022, 10(4), 268; https://doi.org/10.3390/machines10040268 - 8 Apr 2022

Cited by 3 | Viewed by 3097

Abstract

The drilling process in real production places ever-increasing demands on the length and accuracy of the holes made. The drilling of holes beyond a length-to-diameter ratio of 5–10 is called deep drilling. The aim of the research was to determine in detail the [...] Read more.

The drilling process in real production places ever-increasing demands on the length and accuracy of the holes made. The drilling of holes beyond a length-to-diameter ratio of 5–10 is called deep drilling. The aim of the research was to determine in detail the deep-drilling process input conditions, their impact on the stability of the cutting process and the degree to which the output requirements were achieved. The focus of the analysis was on how the monitored technological and physical impacts translate into achieving the required gun-drill life and the quality and dimensional accuracy of deep holes, as well as their overall impact on tool life. Based on the analysis, tests were conducted to verify the impact of individual parameters on tool life. The obtained results were then statistically evaluated and optimized. Drawing on the evaluated experimental results, solutions and procedures were proposed and implemented in the environment of a real operation. This research obtained the optimal values of the frequency of rotation and displacement to ensure maximum tool life while maintaining the efficiency of the production of drilled parts. At the same time, based on the research, a methodology and recommendations for deep-drilling technology were developed. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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20 pages, 4886 KiB

Open AccessArticle

Computer-Aided System for Parametric Design of Ship Hull Structures—CADS-Hull

by Sergey Ryumin and Vladimir Tryaskin

Machines 2022, 10(4), 262; https://doi.org/10.3390/machines10040262 - 7 Apr 2022

Cited by 2 | Viewed by 3429

Abstract

The problem of the parametric design of ship hull structures is considered here. The parametric design of ship hull structures is intended to determine the dimensions of structural elements that meet the requirements of regulatory documents (Rules of Classification Societies/Strength Standards). It is [...] Read more.

The problem of the parametric design of ship hull structures is considered here. The parametric design of ship hull structures is intended to determine the dimensions of structural elements that meet the requirements of regulatory documents (Rules of Classification Societies/Strength Standards). It is shown that, in all existing shipbuilding CAD-CAM systems, the problems of the parametric design of ship hull structures are essentially not affected. A modern methodology for the parametric design of hull structures is proposed, which defines a set of principles for the structural and logical organization of the design process, methods, and technical means for implementing design procedures. The most characteristic methodological principles of the parametric design of ship hull structures and other offshore engineering structures are identified: A systematic approach; modeling as one of the main methods for solving design problems; and a rational design strategy based on iterative search procedures that implement the methodological principle of successive complication of models and procedures for designing structures. The article considers the architecture and methodological foundations of the system for automated parametric design of ship hull structures (CADS-Hull), developed at the Saint Petersburg State Marine Technical University, Russia. The system is intended for use in design bureaus when designing civil ship hull structures on the basis of regulatory requirements of the Russian Maritime Register of Shipping and IACS General Rules in terms of large-capacity tankers, bulk carriers, and container ships. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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19 pages, 5498 KiB

Open AccessArticle

Feasibility of Predictive Models for the Quality of Additive Manufactured Components Based on Artificial Neural Networks

by Sorin D. Grozav, Alexandru D. Sterca, Marek Kočiško, Martin Pollák and Vasile Ceclan

Machines 2022, 10(2), 128; https://doi.org/10.3390/machines10020128 - 11 Feb 2022

Cited by 9 | Viewed by 2526

Abstract

Additive manufacturing technologies present a series of advantages such as high flexibility, direct CAD to final product fabrication, and compact production techniques which make them an attractive option for fields ranging from medicine and aeronautics to rapid prototyping and Industry 4.0 concepts. However, [...] Read more.

Additive manufacturing technologies present a series of advantages such as high flexibility, direct CAD to final product fabrication, and compact production techniques which make them an attractive option for fields ranging from medicine and aeronautics to rapid prototyping and Industry 4.0 concepts. However, additive manufacturing also presents a series of disadvantages, the most notable being low dimensional accuracy, low surface quality, and orthotropic mechanical behaviour. These characteristics are influenced by material properties and the process parameters used during manufacturing. Therefore, a predictive model for the characteristics of additive manufactured components is conceivable. This paper proposes a study on the feasibility of implementing Deep Neural Networks for predicting the dimensional accuracy and the mechanical characteristics of components obtained through the Fused Deposition Modelling method using empirical data acquired by high precision metrology. The study is performed on parts manufactured using PETG and PLA materials with known process parameters. Different Deep Neural Network architectures are trained using datasets acquired by high precision metrology, and their performance is tested by comparing the mean absolute error of predictions on training and validation data. Results show good model generalisation and convergence at high accuracy, indicating that a predictive model is feasible. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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27 pages, 11357 KiB

Open AccessArticle

Effect of the Computational Model and Mesh Strategy on the Springback Prediction of the Sandwich Material

by Pavel Solfronk, Jiří Sobotka and David Koreček

Machines 2022, 10(2), 114; https://doi.org/10.3390/machines10020114 - 3 Feb 2022

Cited by 6 | Viewed by 2033

Abstract

The effect of the computational model and mesh strategy on the springback prediction of the thin sandwich material made of micro-alloyed steel was investigated in this paper. To verify the chosen computational strategy, a comparison of the experimentally obtained specimen (U-bending) with the [...] Read more.

The effect of the computational model and mesh strategy on the springback prediction of the thin sandwich material made of micro-alloyed steel was investigated in this paper. To verify the chosen computational strategy, a comparison of the experimentally obtained specimen (U-bending) with the FEA result was performed. The Vegter yield criterion combined both with the isotropic and kinematic hardening law was used for the calculation. In addition, the effect of the deformation mesh element (surface and volume) on the accuracy of the springback prediction was investigated. It was concluded that the choice of the volume deformation mesh does not significantly improve the accuracy of the results. Moreover, it is quite a time-consuming approach. The much greater influence was monitored by concerning the selection of hardening law, where the anisotropic one was more suitable to be used on the springback prediction of a given sandwich material. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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15 pages, 5686 KiB

Open AccessArticle

An Analytical Method for Tensor Visualization in a Plane

by Tomáš Stejskal, Jozef Svetlík and Jozef Dobránsky

Machines 2022, 10(2), 89; https://doi.org/10.3390/machines10020089 - 25 Jan 2022

Cited by 2 | Viewed by 2476

Abstract

The rendering of tensor glyphs is a progressive process of visualizing the vector space both in fluid dynamics and the latest medical scanning. Nowadays, the rendering accuracy is ensured by numerical methods based on interpolation of tensor functions. The tensor glyph functions to [...] Read more.

The rendering of tensor glyphs is a progressive process of visualizing the vector space both in fluid dynamics and the latest medical scanning. Nowadays, the rendering accuracy is ensured by numerical methods based on interpolation of tensor functions. The tensor glyph functions to visualize significant properties of the vector space. Not all these properties are visualized at all times. The number of properties and their unambiguity depend on the method chosen. This work presents a direct analytical expression covering rank two tensors in a plane. Unlike the methods used so far, this method is accurate and unambiguous one for tensor visualization. The method was applied to the simplest tensor type, which presented an advantage for the method’s analytical approach. The analytical approach to the planar case is significant also because it provides instruction on how to expand analytical calculations to cover higher spatial dimensions. In this way, numerical methods for tensor rendering can be replaced with an accurate analytical method. Full article

(This article belongs to the Special Issue Advances in Computer-Aided Technology)

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