Screw Surface Research Articles

Evaluation of two implant-supported fixed partial denture abutment designs: Influence on screw surface characteristics.

To compare screw surface characteristics between hemi-engaging and non-engaging implant-supported fixed partial denture (FPD) designs after cyclic loading. Twenty-four implants measuring 4.3 × 10mm were mounted on acrylic resin blocks. Specimens were divided into two groups. An experimental group included twelve 3-unit FPD with a hemi-engaging design; a control group included twelve 3-unit FPDs with the conventional design of two non-engaging abutments. Both groups were subjected to two types of cycling loading (CL), first axial loading, and then lateral loading at 30°. Load was applied to the units one million times (1.0 × 106 cycles) for each loading axis. Data on screw surface roughness in three locations and screw thread depth were collected before (BL) and after (AL) each loading type. Screw surface roughness was measured in μm using a mechanical digital surface profilometer and optical profiler. To evaluate screw thread depth in μm, an upright optical microscope Axio-imager 2 was used. To confirm readings made from the optical microscope, four random samples were selected from each group for scanning electron microscopy (SEM) analysis. The effect of cyclic loading was evaluated by averaging values across the two screws within each specimen, then calculating difference scores (DL) between BL and AL (DL = AL - BL). Additional difference scores were computed between the non-engaging screws in each experimental group specimen, and one randomly selected non-engaging screw in each control specimen. This difference was referred to as the non-engaging DL. Statistical significance was assessed using Mann-Whitney U tests (α = 0.05). Comparisons of DL and non-engaging DL by loading type revealed one significant difference regarding surface roughness at the screw thread. Significantly greater mean changes were observed after axial loading compared to lateral loading regarding both DL (axial M = -0.36 ± 0.08; lateral M = -0.21 ± 0.09; U = 20; p = 0.003) and non-engaging DL (axial M = -0.40 ± 0.22; lateral M = -0.21 ± 0.11; U = 29; p = 0.013). No significant differences in screw surface roughness in other sites or thread depth were found between the experimental and control abutment designs in DL or in non-engaging DL. No significant differences were found for DL (axial U = 13, p = 0.423; lateral U = 9, p = 0.150;) or non-engaging DL (axial U = 13, p = 0.423; lateral U = 18, p = 1.00). Results suggest that overall, changes in screw surface physical characteristics did not differ between hemi-engaging and non-engaging designs after evaluating screw surface roughness and thread depth before and after axial and lateral cyclic loading.

Anaerobic adhesives effect on counter-torque of abutment screws on implants with external hexagon and conical connections: An in vitro study.

Abutment screw loosening is a common complication of implant supported prostheses, especially for single crowns. In engineering, anaerobic adhesives (AA) are used to provide chemical locking between screw surfaces, but their application in implantology remains unclear. The purpose of this article is to evaluate, in vitro, the effect of AA on counter-torque of abutment screws for cemented prosthesis on dental implants with external hexagon connection (EHC) and conical connection (CC). Sample was composed by 60 specimens, 30 dental implants with EHC and 30 with CC. Abutments (transmucosal 3 mm straight universal abutment) were installed without AA (control group) or with application of AA with two different adhesive strength: medium strength (LOCTITE® 242) and high strength (LOCTITE® 277). The specimens were subjected to mechanical cycling at 37°C, with a load setting of 133 N, a 1.3 Hz frequency, and 1 200 000 cycles. The abutments were removed, and the counter-torque values were registered. Screws and implants were inspected using a stereomicroscope to verify the presence of residual adhesive and damage the internal structures. The data were analyzed using descriptive statistics and comparison tests (p < 0.05). Comparing to the torque of installation, the medium strength AA kept the counter-torque values for CC implants and the high strength AA kept the counter-torque for EHC implants and increased for CC implants. In the intergroup comparisons, control group presented significantly lower counter-torque values than other groups, both for EHC and CC implants. High strength AA presented similar results to medium strength AA in the EHC implants, but in the CC implants presented higher counter-torque values. Damage in threads was more frequent in the groups that received high strength AA. The use of AA increased the counter-torque of abutment screws, both in implants with EHC and CC.

Determining the Cut-Layer Thickness in Simulating the Machining of a Screw Surface

Determining the Cut-Layer Thickness in Simulating the Machining of a Screw Surface

To determine the effect of plasma nitriding treatment 56 on screw loosening and surface topography of different 78 implant-abutment screw systems with and without thermocycling: An in vitro study.

The aim of this study was to evaluate and compare the effect of plasma nitride-treated abutment screws of two different implant systems on screw loosening and surface topography with and without thermocycling. This was an in-vitro experimental study. Fifty-two abutment screws (Group A: 26 Genesis and Group B: 26 Bredent) underwent plasma nitride treatment and were subdivided into two groups, one without thermocycling and one with thermocycling. Dynamic load was applied and detorque values were evaluated for determining the screw loosening using "independent t-test" with the help of IBM SPSS Statistics 20 and scanning electron microscopy was done to check for surface topography. Inter- and intragroup comparisons were done using independent t-test (SPSS: Statistical Package for the Social Sciences software version 20). Plasma nitriding treatment genesis implant system abutment screw showed more screw loosening (P < 0.05) and surface roughness as compared to bredent with and without thermocycling. From the present study, it was shown that plasma nitride-treated abutment screws decreased the occurrence of screw loosening favoring the bredent implant-abutment system more than the genesis implant-abutment system.

Results of production tests of an experimental diamond crown during exploratory drilling in Kazakhstan

The work is devoted to the results of production tests of a multilayer diamond crown with a comb profile of all impregnated layers separated by diamond-free layers of lower hardness. A distinctive feature of the crown is the placement of diamond-containing layers on a three-way screw surface with a small step. This makes it possible to involve in the process of deepening the fungus into a partially cracked zone the rock lying under the zone of diamond grains introduction. The zone of theoretical justification of the effectiveness of the profile of the matrix. The above-mentioned patent crown under the abbreviation KSB-3M (HQ) has passed production tests at the helogical facility of the Kazakh company. Rocks are mainly represented by carbonaceous-siliceous metagalium of the XIII - IX and partial X-th category. Drilling was carried out with the use of projectile with removable core receiver. 389 wells were drilled with one experimental crown, and most of the footage falls on the IX–category rock, which indicates the great durability of the tool. The mechanical drilling speed varies from 5.5 to 3.5 m/h depending on the rock quality. It was decided to continue experiments with KSB-3M crowns on other geological sections with harder rocks. Keywords: production tests; multilayer immigrated crown; distribution drilling; high rock resistance.

Antibiofilm and enhanced antibiotic delivery by halloysite nanotubes architected dental implant against periodontitis

Dental implant failure remains a predominant problem; poor integration and biofilm formation are the major glitches. The surface modification of implant improves it antibiotic delivery performance and nanostructure incorporation facilitates the versatile behavior. Herein, we have prepared PCPP functionalized HNT and it encapsulated with AMO and MS. FTIR confirms the PCPP coating over the HNT by formation of new peaks at 1640 and 1580 cm−1. Higher stability of HNT nanocomposites was denoted by its zeta value – 45.24 mV. The maximum release of 58% (AMO) and 62% (MS) from the nanocomposites was achieved at the acidic pH. PCPP coated MS-HNT nanocomposites forms lumen size ranging from 15 to 20 nm with uniform surface morphology. Simultaneously, bioactive MS-AMO-PCPP-HNT was deposited on the Ti–6Al–4V screw implant via electrophoretic deposition. The coating of HNT nanocomposites on titanium surface provides 7.24 μm thickness and adhesive strength of 24.6 MPa. After EPD of MS-AMO-PCPP-HNT on Ti–6Al–4V screw, the surface is fully covered by adequate bonding, stable coating, biocompatible and long-lasting antibacterial efficacy. The potentiodynamic study in the SBF shows that the coating provided corrosion protection of the screw. The coated Ti–6Al–4V screw surface composition enhances the biomineralization, promote the cell adhesion, proliferation and promote the soft tissue healing. Compared to the HNT, PCPP-HNT nanocomposites induces the ALP production, increase the cell proliferation rate at 20 μg/mL. In flow cytometry, biocompatible HNT nanocomposites exhibited lesser dead cells of 0.56%. HNT nanocomposites inhibit the 96% (E.coli) and 97% (S. aureus) bacterial inhibition and the rate were higher compared to the AMO alone. Also reduction of 78% of Porphyromonas gingivalis biofilm biomass, the coating is powerfully active against the both pathogenic microbes and bacterial biofilm of peri-implant infection. The nano-architected coating of Ti–6Al–4V screw has great potential in dental implantology.

Research on Surface Quality of 38CrMoAl Polished Based on Abrasive Water Jet

Because the screw surface is slender and complex, it is difficult to process by traditional polishing methods. In order to improve the surface quality of screw, the abrasive water jet polishing (AWJP) technology was used to polish 38CrMoAl steel, which is commonly used in screw. The effects of different inlet pressure, target distance and abrasive particle size on surface roughness are analyzed. The experimental results show that with the increase of inlet pressure, the surface roughness first decreases and then increases. With the increase of target distance, the surface roughness first decreases and then increases. The smaller the abrasive particle size, the better the polishing effect.

Biomechanical comparison between various screw fixation angles for Latarjet procedure: a cadaveric biomechanical study.

The Latarjet procedure is a reliable treatment for the management of anterior glenohumeral instability with glenoid bone loss. However, the biomechanical properties of different fixation angles between screw and glenoid surface (α angle) have rarely been studied. The aim of the study was to investigate and compare the fixation stability, failure load, and failure mechanism between different α angles for Latarjet procedures, which were performed on cadaver specimens. Twenty-four shoulder specimens (8 in each of 3 groups) were dissected free of all soft tissue, and a 25% glenoid defect was created. The coracoid process was osteomized and fixed with 2 screws at 3 different α angles: 0° (group A), 15° (group B), and 30° (group C). Specimens were mounted to a testing apparatus, and cyclic loading (100 cycles at 1Hz) was applied with a staircase protocol (50, 100, 150, and 200N). Gross graft displacement and interface displacement were measured. The ultimate failure loads and failure mechanisms were recorded. There was no significant difference in gross displacement under any cyclic load between 3 groups. However, a significant larger interface displacement was noted in group C than in group A in 150-N cyclic loading (P=.017). Under failure strength testing, all 24 specimens failed because of screw cutout from the glenoid, and the ultimate failure load was similar among the three groups. Compared with the 0° α angle, the displacement after cyclic loading did not significantly increase when the α angle was increased to 15° but significantly increased at 30° for Latarjet procedures, which were performed on cadaver specimens. The results suggest that surgeons should apply the screws as parallel as possible to the glenoid surface when performing the Latarjet procedure. Although mild deviation may not reduce fixation stability, α angles greater than 30° should be avoided.

Thread shape, cortical bone thickness, and magnitude and distribution of stress caused by the loading of orthodontic miniscrews: finite element analysis

Cortical bone thickness is assumed to be a major factor regulating miniscrew stability. We investigated stress distribution in two miniscrews with different thread shapes (type A and B) and in cortical bone of three different thicknesses using three-dimensional (3D) finite element (FE) models. More specifically, 3D FE models of two different miniscrews were created and placed obliquely or vertically into a cylindrical bone model representing different cortical bone thicknesses. When force was applied to the miniscrew, the stress distribution on the screw surface and in the peri-implant bone was assessed using FE methodology. Miniscrew safety was evaluated using a modified Soderberg safety factor. Screw head displacement increased with a decrease in cortical bone thickness, irrespective of screw type. The smallest minimum principal stresses on the screw surfaces remained constant in type A miniscrews on changes in cortical bone thickness. Minimum principal stresses also appeared on the cortical bone surface. Lower absolute values of minimum principal stresses were seen in type A miniscrews when placed vertically and with upward traction in obliquely placed type B miniscrews. Both miniscrews had acceptable safety factor values. Taken together, orthodontists should select and use the suitable miniscrew for each patient in consideration of bone properties.

ROLLING OF A DEVELOPABLE HELICOID OF THE SCREW LINE ALONG ITS BENDING

A very common helical surface in various mechanisms is a straight closed helicoid or screw conoid, known in the technical field as a screw. Considering the wide application of screws, there are various methods of their production (winding, rolling, stamping, stretching flat rings welded together on a shaft). Since the surface of the screw conoid is nondevelopable, the flat ring is an approximate sweep of the screw, since an exact sweep does not exist. During the formation of the turn of a screw conoid from a flat ring, plastic deformations occur in it, caused by the transformation of a developable surface into a nondevelopable one. &#x0D; It is known from differential geometry that any screw surface can be bent into a surface of revolution. For a screw conoid, such surface is a catenoid. The paper presents parametric equations for the continuous bending of a catenoid into a screw conoid. It is proposed to replace the compartment of the catenoid, which corresponds to the given compartment of one turn of the conoid, with a truncated cone. The sweep of this cone in the form of a flat ring can be considered a blank for forming the surface of a conoid. A comparative analysis of the sizes of the ring obtained by the proposed method with the sizes that can be obtained according to the formulas of the reference literature were made. Although there are differences, but they are practically insignificant.&#x0D; As a result of the study of the continuous bending of a catenoid into a screw conoid, an improvement of the process of such bending is proposed. In one of the existing methods of forming a screw from flat rings, several rings in the form of a sector are proposed to be welded together and then stretched to obtain a screw with the same number of turns. Welded rings are put on the shaft, one end is fixed to it (for example, by welding), and the other is stretched to the desired size. With this method, the twisting of the workpiece around the axis of the shaft is not taken into account. It is necessary to bend truncated cones from separate sectors, weld them together, and only then stretch them. In this case, the twist angle is already embedded in the workpiece in the form of welded cones.

Improving the Stability of a Hemipelvic Prosthesis Based on Bone Mineral Density Screw Channel and Prosthesis Optimization Design.

In pelvic reconstruction surgery, the hemipelvic prosthesis can cause significant changes in stress distribution due to its high stiffness, and its solid structure is not suitable for osseointegration. The purpose of this study was to identify a novel bone mineral density screw channel and design the structure of the prosthesis so as to improve the distribution of stress, promote bone growth, and enhance the biomechanical properties of the prosthesis. The mechanical characteristics of bone mineral density screw and traditional screw were compared by finite element analysis method, and redesigned by topology optimization. The direction of the newly proposed screw channel was the posterolateral entrance of the auricular surface, ending at the contralateral sacral cape. Compared to the original group, the maximum stress of the optimized prosthesis was decreased by 24.39%, the maximum stress of the sacrum in the optimized group was decreased by 27.23%, and the average strain energy density of the sacrum in the optimized group was increased by 8.43%. On the surface of screw and connecting plate, the area with micromotion more than 28 μm is reduced by 12.17%. On the screw surface, the area with micromotion more than 28 μm is reduced by 22.9%. The newly determined screw channel and optimized prosthesis design can effectively improve the biomechanical properties of a prosthesis and the microenvironment of osseointegration. This method can provide a reference for the fixation of prostheses in clinical pelvic reconstruction.

STUDY OF THE MOVEMENT OF SOIL PARTICLES ON THE SURFACE OF A SCREW TILLAGE WORKING BODY

This study considers the interaction of soil particles with a screw tillage body, the working surface of which is made in the form of a deployed helicoid and substantially differs from the screw. Furthermore, the unfolded surface is characterised by manufacturability of the working body, since it is possible to calculate the geometric dimensions of a flat workpiece, which is formed into a finished product by simple bending with minimal plastic deformations. The purpose of this paper was to conduct theoretical and experimental studies of the movement of soil particles along the helical surface of the tillage working body, which is made in the form of a deployed helicoid. Mathematical modelling of the processes of movement of soil particles along the helical surface of a tillage working body was described based on general laws and principles of analytical and differential mathematics, theoretical and analytical mechanics. Experimental studies were carried out using a methodology with elements of mathematical statistics, mathematical methods of optimal planning of a multifactor experiment. The analysis of the results of experimental and theoretical studies was performed using applied computer programmes and systems. Experimental studies were conducted according to standard and independently developed methods. Results: a mathematical model of the movement of soil particles along the helical surface of the tillage body was developed, and it was established that when the angle of attack of the helical tillage working body increases, the lifting value of soil particles increases and the area of their dispersion by the helical surface increases. The value of the coefficient of friction does not substantially affect the shape of the trajectory of the soil particle. The quality of loosening the soil most depends on the angle of attack of the screw surface and the angular speed of rotation of the working body. The materials of this paper can be used by scientists for further research and practices in the selection of tillage units.

스크류용 합금강의 마모 특성에 관한 연구

Purpose: The screws used in agricultural machinery are worn by friction due to relative motion during prolonged high-pressure use. The wear can be categorized as abrasion and cohesion wear, which shorten the performance and life of agricultural machinery and eventually lead to failure. This study focused on determining the wear rate of the screw surface in dehydration machinery.<BR>Methods: We sought to select the optimal material by comparing and analyzing the wear characteristics of three types of materials: STS, SCM, and SNCM. The wear test was performed under variable load, dry, and wet conditions on a total of 3 samples using a pin-on-disk wear tester. The friction coefficient, amount of wear, and specific wear rate were obtained from the test results and compared for the three materials.<BR>Results: The friction surface was imaged using SEM. It was found that the specific wear rate of STS was the highest under all load conditions in both dry and wet environments. The specific abrasion rate of SCM was similar to that of SNCM in a dry environment but the lowest in a wet environment, revealing its excellent abrasion resistance.<BR>Conclusion: A material with high wear resistance was identified by analyzing the wear characteristics of three types of materials. Moreover, its use increased durability of the screw, a critical component in dewatering machines.

An Approach to Intraoperatively Identify the Coronal Plane Deformities of the Distal Tibia When Treating Tibial Fractures with Intramedullary Nail Fixation: a Retrospective Study.

ObjectiveTo develop a new approach to intraoperatively identify the presence of coronal plane deformities (both valgus and varus) when treating tibial fractures with closed reduction and intramedullary nail fixation.MethodsA retrospective analysis was conducted by enrolling 33 consecutive patients with tibial fractures who received closed reduction and intramedullary nail fixation from January 2018 to January 2019 at our trauma center. Out of the 33 patients, 23 were males and 10 were females and the average age was 41 years (ranging 22 to 69 years of age). Standard anteroposterior and lateral preoperative radiographs were routinely performed. After intraoperatively inserting the tibial intramedullary nail through the standard entry point, the parallel relationship between the distal horizontal interlocking screw and the tibiotalar joint surface on the anteroposterior fluoroscopy was used to determine the occurrence of valgus or varus deformities of the distal tibial fragment. Radiographic and clinical outcomes were analyzed using the average interval from injury to surgery, the lateral distal tibial angle (LDTA) of the unaffected and affected sides, complications and the Olerud–Molander ankle score.ResultsAll 33 patients were postoperatively followed for 13 to 25 months (mean 18.7 months). The fractures achieved bone union at an average of 4.3 months (ranging from 3 to 6 months). The total complication rate was 60.6% (20 cases), including four cases that showed deep vein thrombosis, one case showing an infection and delayed union and 15 cases showing slight to moderate anterior knee pain. The postoperative LDTA of the unaffected side measured 87.3° to 89.6 ° (average 88.7° ± 0.8°), and the LDTA of the affected side was 87.5° to 90.4° (average 88.9° ± 1.1°). There was no significant difference between the unaffected and affected sides (t = −1.865, P = 0.068). The intraoperative measurement indicated six cases of valgus angulation and three cases of varus angulation deformities, and all deformities were corrected during surgery. According to the Olerud–Molander ankle score, clinical outcomes demonstrated 22 excellent cases, eight good cases, two fair cases, and one poor case 12 months after surgery.ConclusionThe parallel relationship between the distal horizontal interlocking screw and tibiotalar joint surface on intraoperative anteroposterior films were able to determine the onset of valgus or varus angulations of the distal tibial fragment in the fracture zone after the tibial intramedullary nail was inserted through the standard entry point.

INNOVATIVE THREAD METHOD THROUGH CYLINDRICAL HOLES

Innovative activity in the field of engineering and technology, based on the use of best practices, contributes to scientific and technological progress in production. The latest projects in the field of technology significantly increase the technical and economic performance of enterprises. Innovative technical solutions of production nature significantly improve the structure and quality of production. Given the level of the proposed technological changes in the manufacture of threads in through holes, these innovations cover the field of combinatorial and partial. Today mechanical engineering is characterized by mechanization and automation of technological processes, a wide range of products of various parts. Among the non-detachable and detachable joints of parts, the threaded connection is the most common. Simplicity, reliability, the ability to adjust the force with which the conjugate surfaces come into contact, the possibility of repeated cycles of disassembly and assembly, etc., make this type of connection the most commonly used in mechanisms and machines of modern engineering. With the simplicity of the contact pair of threaded joints, where one of them contains the outer and the other the inner screw surface, during their manufacture there are problems that significantly inhibit production. The subject of research of this article is the solution of difficulties of manufacturing of an internal cut in through openings of small diameter by means of a tap. According to various sources, up to 80% of marriage is due to breaking taps. Studies by a group of scientists has found that more than 75% of taps break when the reverse (reverse) stroke of the tap, when the torque reaches its maximum value. The reverse scheme of production of a screw profile of a cutting surface by means of the mechanized devices and their alternative analogs, and also machines of drilling group, is offered.

Study of quality criteria for two-phase iron-based composite coatings formed by plasma spraying

The increasing relevance in the field of repair and restoration of machines and mechanisms is acquiring gas-thermal methods of applying functional coatings to the working surfaces of parts of machine assemblies. The purpose of gas-thermal coating methods is to provide and obtain special physical and mechanical properties of the surface of the part, as well as to restore worn-out components and mechanisms after their long-term and intensive operation. Plasma spraying of composite coatings is an effective method of gas-thermal treatment of the surface of a part. In this paper, a study was conducted on the optimal selection of material for plasma spraying of a part, taking into account its operational features and types of wear of working surfaces. In particular, the operating conditions of the screw of the conveying conveyor are analyzed. The technological features of the application of composite materials by plasma spraying technology are considered. The theoretical selection of a two-phase dispersed-filled composite for application to the working surfaces of the screw in order to restore and harden it has been carried out. Studies and analysis of one of the main indicators of the quality of the formed coating after plasma spraying – the magnitude of the resulting residual stresses (stretching and compression) have been carried out. Taking as a basis the kinematic modes and geometry features of the working surfaces of the screw, as well as the criteria for the formation of the thickness of the sprayed layer, the calculation equations for determining the residual stresses arising on the screw and cylindrical surfaces of the screw of the conveying conveyor are obtained. It is concluded that in order to achieve the required physical and mechanical properties of the coating, the volume fraction of the filler in the matrix of the PG-SR4 composite powder should be in the range of 20–25%. Therefore, it is possible to use in practice a particulate-filled composite of the NiСrВSiFе type with 20–25% reinforcing TiC filler particles in order to restore parts of machines and mechanisms.

Mechanobiological model to study the influence of screw design and surface treatment on osseointegration

This study aims at suggesting a new approach to peri-implant healing models, providing a set of taxis-diffusion-reaction equations under the combined influence of mechanical and biochemical factors. Early events of osseointegration were simulated for titanium screw implants inserted into a pre-drilled trabecular bone environment, up to 12 weeks of peri-implant bone healing. Simulations showed the ability of the model to reproduce biological events occurring at the implant interface through osteogenesis. Implants with shallow healing chamber showed higher proportions of lamellar bone, enhanced by the increase of mechanical stimulation. Osteoconduction was observed through the surface treatment model and similar bone healing patterns compared to in vivo studies.

Ergonomic aspects of material separation process modeling on stationary screw surfaces

The motion of material particles on gravitational surfaces, ie the motion of particles on surfaces under the action of its own weight, is used in special devices for their separation by physical and mechanical properties. For this purpose stationary screw surfaces of a steady step are applied. A number of papers have now considered the relationship between the kinematic parameters of motion, the coefficient of friction and the design parameters of the separator, when its surface is a deployable helicoid. The purpose of the study is to investigate helical surfaces with different design parameters in order to improve their separation ability through mathematical and geometric modeling of the process without making surface models. The problem of finding the trajectory of a material particle on the surface under the action of its own weight is preceded by the problem of finding the trajectory on an inclined plane. If a material particle with a certain initial velocity vо and a certain angle of inclination to the horizon falls on an inclined plane, it will move along a certain curve (in the absence of friction and air resistance, the trajectory will be a parabola). A system of equations is obtained, which describes the motion of a material point on the gravitational surface in the general case. If it is created for a specific surface, nonlinear and numerical methods must be used to integrate it. Modern software products allow not only to find the trajectory of the particle, but also to show it on the surface and even make an animation that essentially replaces high-speed shooting. This approach makes it possible to study the kinematic parameters of motion on different helical surfaces without full-scale samples of these surfaces, which significantly reduces the cost of finding the right surfaces. The motion of particles along a helical conoid and a deployable helicoid is considered. Simulation of the motion of a material particle on helical surfaces and its study by modern means of numerical integration and visualization have shown that for different surfaces the nature of the motion of the particle will also be different. When moving on the surface of the helical conoid, the particle in the presence of friction first accelerates, and then stops at a considerable distance from its axis. To prevent this, you need to take a limited compartment of the conoid both in height and on its periphery. When a particle moves on the surface of a deployed helicoid, its velocity becomes constant over time, and the trajectory after that will be a helical line. Key words: particle motion, helical surfaces, helical conoid, deployable helicoid, simulation

Математичне моделювання процесу розділення матеріалу на стаціонарних гвинтових поверхнях

The motion of material particles on gravitational surfaces is used in special devices for their separation by physical and mechanical properties. For this purpose stationary screw surfaces of a constant step are applied. The purpose of the study is to investigate helical surfaces with different design parameters in order to improve their separation ability through mathematical and geometric modeling of the process without making surface models. The problem of constructing the trajectory of a material particle on the surface under the action of its own weight is preceded by the problem of finding the trajectory on an inclined plane. Modern software products make it possible not only to find the trajectory of the particle, but also to show it on the surface and even make an animation, which essentially replaces high-speed camera recording. This approach makes it possible to study the kinematic parameters of motion on different helical surfaces without full-scale samples of these surfaces, which significantly reduces the cost of finding the desired surfaces. The trajectories of the particle on the surface of the helical conoid and the deployable helicoid are obtained. It is established that when moving on the surface of a helical conoid, the particle in the presence of friction first accelerates, and then stops at a considerable distance from its axis. To prevent this, its need to take a limited compartment of the conoid both in height and on its periphery. When a particle moves on the surface of a helicoid, its velocity becomes constant over time, and the trajectory after that will be a helical line. The developed approaches make it possible to study the process of material separation not only after stabilization of motion, but also during the transition process, as it became possible to visualize it. This will allow you to choose the surface compartment of the optimal size, which will provide the desired productivity of separation due to the dispersion of particles with different coefficients of friction on its surface. Key words: material particle, trajectory, material separation, helical conoid, helicoid

Developing the Smart Sorting Screw System Based on Deep Learning Approaches

The deep learning technique has turned into a mature technique. In addition, many researchers have applied deep learning methods to classify products into defective categories. However, due to the limitations of the devices, the images from factories cannot be trained and inferenced in real-time. As a result, the AI technology could not be widely implemented in actual factory inspections. In this study, the proposed smart sorting screw system combines the internet of things technique and an anomaly network for detecting the defective region of the screw product. The proposed system has three prominent characteristics. First, the spiral screw images are stitched into a panoramic image to comprehensively detect the defective region that appears on the screw surface. Second, the anomaly network comprising of convolutional autoencoder (CAE) and adversarial autoencoder (AAE) networks is utilized to automatically recognize the defective areas in the absence of a defective-free image for model training. Third, the IoT technique is employed to upload the screw image to the cloud platform for model training and inference, in order to determine if the defective screw product is a pass or fail on the production line. The experimental results show that the image stitching method can precisely merge the spiral screw image to the panoramic image. Among these two anomaly models, the AAE network obtained the best maximum IOU of 0.41 and a maximum dice coefficient score of 0.59. The proposed system has the ability to automatically detect a defective screw image, which is helpful in reducing the flow of the defective products in order to enhance product quality.