Tool Head Research Articles

Optimized Control Method for Fused Deposition 3D Printing Slice Contour Path Based on Improved Hopfield Neural Network

ABSTRACT This paper presents a novel approach for optimizing the contour path of fused deposition 3D printing slices to mitigate the limitations of inefficiency and time consumption associated with the process. The proposed algorithm leverages the Hopfield Neural Network (HNN) and an improved whale optimization algorithm to plan the printing order of each contour and optimize the network parameters, respectively. In particular, the algorithm transforms the running trajectory planning problem of the assembled tool head into a travel problem, which allows for a more efficient path planning approach. The HNN is then employed to determine the optimal path for each contour, with the network optimization process utilizing a nonlinear weight update method to overcome the drawbacks of the traditional HNN that is prone to generating invalid paths and falling into local optimality during operation. The network optimization process is designed to automatically adjust the link weights between neurons within a specific range, thereby ensuring that the network reaches the desired energy minima and outputs the optimal path for 3D printed slice contours. The proposed algorithm was tested in part printing experiments, and the results demonstrated a significant reduction in single-layer contour path lengths, printing times, and an enhancement in dimensional accuracy and surface quality of the printed parts compared to the traditional parallel scanning method. The proposed algorithm represents a significant contribution to the field of 3D printing, as it provides an efficient and effective approach for optimizing the contour path of fused deposition 3D printing slices. The findings of this study hold significant implications for improving the efficiency and quality of 3D printing and could potentially lead to further advancements in the field.

Injury patterns in patients with severe traumatic brain injuries from motor crashes admitted to Mulago hospital accidents & emergency unit.

The global burden of Road Traffic Crashes (RTC) is increasing. Uganda has one of the highest rates of RTCs in Sub-Sahara. Victims of RTCs sustain varying degrees of injuries depending on factors including the velocity at time of impact, protective gear; and if it was a motorcycle-motorcycle or motorcycle-vehicle crash. High speed collisions can result in severe forms of injuries and polytrauma. Some injuries are undetected. A cross sectional study was carried at Mulago Hospital Accidents & Emergency Unit, between November 2021 and February 2022; on all adult patients (≥18 years) with severe head injury from motor road traffic crashes. The study looked at injury patterns and assessed the relationship of polytrauma in patients with severe head injury to the mechanism of injury (motorcycles versus vehicles). Data were extracted from patient charts using a validated data abstraction tool and complete head to toe physical examination was carried out and injuries recorded. Data were analysed to determine the relationship of polytrauma in patients with severe head injury to the mechanism of injury. The participants were predominantly males with a population median age of 32 (25-39). The commonest modes of transportation of patients to the hospital were Police Pickup trucks (40%) and ambulance (36.1%). Among motorcycle RTCs, (19.2%) wore helmets; 21.2% had protective gear; with injury identified mainly in; the limbs (84.8%), neck (76.8%), chest (39.4%), and abdomen (26.3%). Patients from vehicle RTCs were 19% more likely to have polytrauma compared to patients from motorcycle RTCs. This study showed that patients who sustain severe traumatic brain injuries from vehicle crashes have an increased likelihood of having multiple injuries, compared to patients from motorcycle RTCs. For motorcycle users, injuries mostly affect the limbs. At particular risk are motorcyclists who do not wear helmets and protective coveralls.

Finite Element Simulation and Experimental Investigation on Progressive Forming

A non-linear finite element technique is used to study the progressive forming process of the sheet, and the elastic-plastic distribution is analyzed based on Abaqus/Explict. Finite element simulations of progressive forming with different process parameters were carried out to analyse the effects of the tool head diameter, layer feed and sheet properties on forming quality. The results show that increasing the tool head diameter or decreasing the layer feed will result in better sheet forming quality, and the influence of the tool head diameter on the sheet forming quality is greater than that of the layer feed, and the selection of materials and the selection of suitable process parameters are more conducive to the improvement of forming quality and forming efficiency.

Stiffness characteristics analysis of a Biglide industrial parallel robot considering the gravity of mobile platform and links

For the machining process of industrial parallel robots, the gravity generated by the weight of mobile platform and links will lead to the deviation of the expected machining trajectory of the tool head. In order to evaluate this deviation and then circumvent it, it is necessary to perform the robotic stiffness model. However, the influence of gravity is seldom considered in the previous stiffness analysis. This paper presents an effective stiffness modeling method for industrial parallel robots considering the link/joint compliance, the mobile platform/link gravity, and the mass center position of each link. First, the external gravity corresponding to each component is determined by the static model under the influence of gravity and mass center position. Then, the corresponding Jacobian matrix of each component is obtained by the kinematic model. Subsequently, the compliance of each component is obtained by cantilever beam theory and FEA-based virtual experiments. In turn, the stiffness model of the whole parallel robot is determined and the Cartesian stiffness matrix of the parallel robot is calculated at several positions. Moreover, the principal stiffness distribution of the tool head in each direction over the main workspace is predicted. Finally, the validity of the stiffness model with gravity is experimentally proved by the comparison of the calculated stiffness and measured stiffness in identical conditions.

Elastic properties of the non-mixing copper donor assisted material in friction stir welding of aluminum alloys using nanoindentation

Friction stir welding of high-strength materials such as steels is the impeded by the lack of the vast heat input needed to start the process. Contact friction is considered the most dominant source of heat generation for FSW steels which tends to cause severe wear conditions of the tool hear. To relieve the extreme wear conditions that occur on the tool heads because of FSW steels, we introduce the non-mixing Cu donor stir material to friction stir welding of aluminum alloys. The elastic properties of the Cu donor assisted friction stir welded aluminum alloys are measured using nanoindentation. The hardness and elastic modulus were measured for two regions, the base metal (BM) and the stir zone (SZ). The measurements were conducted for 20% and 60% Cu non-heat treated (NHT) and heat-treated (HT) samples. The nanomechanical properties were measured using nanoindentation with the continuous stiffness method (CSM) in depth control. The HT samples are softer than the NHT samples as expected. However, the 20% Cu NHT and HT samples depicted the same hardness at the SZ. Similar results were observed for the 60% Cu donor stir samples. It therefore concluded that the SZ is softer than the BM for the 20% and 60% Cu donor stir material as expected. The hardness of the weld at the SZ is similar to the hardness of the Al6061-T6 plate, suggesting that the Cu donor stir material did not impact the hardness properties of the Al6061-T6 plate due to the depletion of the Cu donor stir material during the welding process, an important result of the concept of the donor material. The elastic moduli of the Cu donor stir welded samples vary between 75~85 GPa at a depth of indentation of ~4600 nm, which are different from the elastic moduli of Cu 110 (117.2 GPa) and similar to the elastic modulus of aluminum alloys (68.9 GPa), an important outcome.

Study on the Mechanism of Burr Formation by Simulation and Experiment in Ultrasonic Vibration-Assisted Micromilling

Due to the strong plasticity of Inconel 718 and the significant size effect of micromachining, a large number of burrs will be produced in traditional processing. The addition of ultrasonic vibration during machining can reduce the burr problem. The mechanism of burr generation in traditional micromilling (TMM) and ultrasonic vibration-assisted micromilling (UVAMM) was analyzed by simulation, and verified by corresponding experiments. It is found that applying high-frequency ultrasonic vibration in the milling feed direction can reduce cutting temperature and cutting force, improve chip breaking ability, and reduce burr formation. When the cutting thickness will reach the minimum cutting thickness hmin, the chip will start to form. When A/ƒz > 1/2, the tracks of the two tool heads start to cut, and the chips are not continuous. Some of the best burr suppression effects were achieved under conditions of low cutting speed (Vc), feed per tooth (ƒz), and large amplitude (A). When A is 6 μm, the size and quantity of burr is the smallest. When ƒz reaches 6 μm, large continuous burrs appear at the top of the groove. The experimental results further confirm the accuracy of the simulation results and provide parameter reference.

Numerical Simulation of the Donor-Assisted Stir Material for Friction Stir Welding of Aluminum Alloys and Carbon Steel

In this research effort, we explore the use of a donor material to help heat workpieces without wearing the tool or adding more heat than necessary to the system. The donor material would typically be a small piece (or pieces) of material, presumably of lower strength than the workpiece but with a comparable melting point. The donor, a sandwich material, is positioned between the tool head and the material to be welded, where the tool initially plunges and heats up in the same manner as the parent material that is intended for welding. The donor material heats up subsequent to tool penetration due to friction and as a result heats up the material beneath it. This preheating technique softens the harder parent material, which helps to minimize tool wear and produce better weld performance. The goal is to investigate the use of the donor material as a preheating technique that minimizes wear and tear on the tool head without negatively impacting the structural properties of the weld. To demonstrate the donor material concept, a combination of Cu-Al, Cu-1045 Carbon steel (CS), and Al-1045 CS sets of donor and parent materials were used in the simulation, in addition to control samples Al-Al and CS-CS. We simulated two thicknesses of donor material 25 and 50% of the parent material thickness, respectively. The simulation suggests that the donor material concept generates phenomenal results by reducing the temperature and axial forces for the friction stir welding of aluminum AA6061 and carbon steel 1045. It also assists downstream during welding, resulting from frictional mechanical work which is converted into stored heat.

Design & Fabrication of Quad Processing Machine

In this project, the quad processing machine for cutting, shaping, grinding and drilling machines is kept to be in same attachment. This eliminates the risk of material handling and to the machine table. This unit is driven by 0.25 H.P. three phase motor of 1440 rpm. This is linked with the cast-iron (CI) slider. This enables the slide to get the rotation movement into reciprocating motion having a stroke length of 75mm. The head of the slotting can be tilted to be getting the shaping machine at a desired angle. The head is welded to the slider at the bottom edge. In this machine there can be one operation will be done which is slotting or shaping operation. In the tool head, a slot & tapped holes are provided for holding the tool. According to the height of the job the head can be moved up or down by means of column and can be fixed using a clamp provided. If a table with a machine vice having longitudinal moment is attached to the machine, the setup can be used for machining slots and shaper in small jobs like pulleys etc. Instead of MS sheet, if CI is used for body and other parts it will have longer life, less friction, better lubrication and the production cost will also be low. This machine can also be used for production of small washers by punching if suitable dies and brake arrangement are fixed.

Free-form Bending Control using Optimal Residual Strategies

Free-form bending is a bending technique, whereas the bending tool head combines both linear and rotary motions. One problem with free-form bending is that an incorrectly bent tube section can no longer be corrected. Therefore, if a defect is detected during bending, a strategy for bending the remaining tube sections must be determined in such a way that the overall shape of the tube is as close as possible to the desired one. In this paper, a solution based on optimal recalculation of the residual trajectories of the bending tool head is presented and different cost functions are discussed in terms of their effect on the overall shape. Simulation results have shown a significant improvement of the resulting end shape of the workpiece upon subjecting it to perturbation.

On Variable Scale Evolution of Stress and Strain of TA2 Titanium Plate in Combined Hammering

Combined peening composed of multiple peening processes or peening media is a surface treatment method for comprehensive control of the macro shape and performance of the part. Compared to combined peening, the impact kinetic energy of the combined hammering can be easier to control over a wide range, and the hammer tool head size is larger than the shot. This paper focused on investigating the effect of combined hammering treatment, 6 mm and 14 mm tool heads with peening density 3.7 to 4.2/mm2, on the variable scale evolution of titanium TA2. Three types of contact relation between the tool head and existing dimple were proposed for impacting at the same position. The size of the dimple of combined hammering varies in width or depth direction, resulting in nest morphology composed of different size dimples. The cross-section microstructure of the test plate was observed, and the gradient changes of dislocation, slip, and grain size are smoothed by combined hammering. The change in hammer tool head size makes the target plastic deform at different depths. The hammering sequence has a significant influence on the evolution of stress and strain fields. When the tool head is first large and then small, a large compressive residual stress near the surface is introduced, about 1000 Mpa; on the contrary, the compressive residual stress distributes uniformly in the depth direction, with an affected layer depth of about 4.4 mm. The measured dimple size and residual stress verified the reliability of the simulation results.

Investigation and machine learning-based prediction of parametric effects of single point incremental forming on pillow effect and wall profile of AlMn1Mg1 aluminum alloy sheets

Today the topic of incremental sheet forming (ISF) is one of the most active areas of sheet metal forming research. ISF can be an essential alternative to conventional sheet forming for prototypes or non-mass products. Single point incremental forming (SPIF) is one of the most innovative and widely used fields in ISF with the potential to form sheet products. The formed components by SPIF lack geometric accuracy, which is one of the obstacles that prevents SPIF from being adopted as a sheet forming process in the industry. Pillow effect and wall displacement are influential contributors to manufacturing defects. Thus, optimal process parameters should be selected to produce a SPIF component with sufficient quality and without defects. In this context, this study presents an insight into the effects of the different materials and shapes of forming tools, tool head diameters, tool corner radiuses, and tool surface roughness (Ra and Rz). The studied factors include the pillow effect and wall diameter of SPIF components of AlMn1Mg1 aluminum alloy blank sheets. In order to produce a well-established study of process parameters, in the scope of this paper different modeling tools were used to predict the outcomes of the process. For that purpose, actual data collected from 108 experimentally formed parts under different process conditions of SPIF were used. Neuron by Neuron (NBN), Gradient Boosting Regression (GBR), CatBoost, and two different structures of Multilayer Perceptron were used and analyzed for studying the effect of parameters on the factors under scrutiny. Different validation metrics were adopted to determine the quality of each model and to predict the impact of the pillow effect and wall diameter. For the calculation of the pillow effect and wall diameter, two equations were developed based on the research parameters. As opposed to the experimental approach, analytical equations help researchers to estimate results values relatively speedily and in a feasible way. Different partitioning weight methods have been used to determine the relative importance (RI) and individual feature importance of SPIF parameters for the expected pillow effect and wall diameter. A close relationship has been identified to exist between the actual and predicted results. For the first time in the field of incremental forming study, through the construction of Catboost models, SHapley Additive exPlanations (SHAP) was used to ascertain the impact of individual parameters on pillow effect and wall diameter predictions. CatBoost was able to predict the wall diameter with R2 values between the range of 0.9714 and 0.8947 in the case of the training and testing dataset, and between the range of 0.6062 and 0.6406 when predicting pillow effect. It was discovered that, depending on different validation metrics, the Levenberg–Marquardt training algorithm performed the most effectively in predicting the wall diameter and pillow effect with R2 values in the range of 0.9645 and 0.9082 for wall diameter and in the range of 0.7506 and 0.7129 in the case of the pillow effect. NBN has no results worthy of mentioning, and GBR yields good prediction only of the wall diameter.

СОЗДАНИЕ КАНАВОЧНОГО И ОТРЕЗНОГО ИНСТРУМЕНТА С КАНАЛАМИ ДЛЯ ОХЛАЖДЕНИЯ, ИЗГОТОВЛЕННЫМИ С ПОМОЩЬЮ АДДИТИВНЫХ ТЕХНОЛОГИЙ

The study objective is to develop the design and technology of manufacturing grooving and cutting tools with internal channels for supplying coolants under high pressure. The design assumes the use of conventional replaceable cutting carbide plates (CCP) offered by many manufacturers. Due to the fact that drilling of narrow channels in the cutter is very problematic, it is proposed to manufacture the front part of the cutter, which secures the replaceable cutting carbide plate, in an additive way. The back of the cutter (holder) can be made by traditional methods. At the same time, the options for fixing the replaceable cutting carbide plates (CCP) are analysed, as well as basing it in the holder and the method of coolant supply. The variants of the design of grooving and cutting tools according to the criterion of treatment features are considered. Special attention is paid to the design of cutters for the surface treatment of narrow deep grooves. The novelty of the work is in carrying out research related to the development of a new design of cutting tools with channels for coolant supply and the method of its manufacture. The research method is 3D modeling of the tool and computer analysis of the stress state on the support surface of the tool head. The development of designs of grooving and cutting tools with cooling channels made with the help of additive technologies is currently not described in the scientific literature. Study result: 3D models, drawings of tools for cutting radial and axial grooves and tools for cutting the edges are obtained. Studies of the stressed state of the support surfaces for CCP are carried out. Prototypes of the corresponding three types of cutters are made. Conclusions: the conducted research proves the prospects of using the method. Thanks to the use of the developed tool, it is possible to increase the productivity of machining parts made of hard-to-machine material, including titanium alloys and heat-resistant steels. As a result, the task of creating a domestic cutting tool that surpasses imported analogues in its properties can be solved.

Continuous repair of groove damages using solid-state friction rolling additive manufacturing method

A solid-state and continuous groove repair technology was proposed for aluminium alloy based on friction rolling additive manufacturing (FRAM). The feasibility of FRAM was explored by repairing three types of prefabricated groove damages in aluminium alloy plates. A well-repaired joint for trapezoidal groove was obtained when the press-in depth of the tool head was 2 mm. The press-in depth was the key factor to complete filling of the groove damage. Effective grain refinement of the repair centre and the significant refinement area are observed, which leads to the hardness of these two areas reaching 99% and 102% of the substrate, respectively. The material migration behaviour of the filling material during the process was clarified.

Revealing the bonding mechanisms between deposit and substrate of the friction rolling additive manufactured hybrid aluminum alloys

Friction rolling additive manufacturing (FRAM) is an emerging solid-state additive manufacturing technology for high-strength aluminum alloys that are prone to produce solidification defects using fusion-based additive manufacturing method. However, the mechanisms responsible for good bonding between the FRAM interlayers remain unclear. This study successfully reveals such mechanisms for FRAM-produced hybrid AA2319 and AA6061 aluminum alloys using 3D X-ray computed tomography, electron backscatter diffraction, and transmission electron microscopy. Three findings concerning the quality of bonding between adjacent layers in FRAM were obtained. Firstly, material plastic flow and macroscopic migration behavior occurred simultaneously along the longitudinal and transverse directions at the interlayer, forming a macroscopic mechanically interlocking nonplanar interface. The convex thread at the tool head increased the material flow in the transverse direction, facilitating material mixing in the adjacent layer. Secondly, severe plastic deformation resulted in significant grain refinement on both sides of the interface. The average grain size reduction rates for the sides of AA2319 and AA6061 were 98.3% and 95.9%, respectively. Thirdly, direct contact with no obvious oxides resulted in complete metallurgical interface bonding. These findings can aid in the elucidation of the basic physical process of FRAM and provide guidance for process parameter optimization and tool head design in the future. • Mechanically interlocked non-planar interface was formed during the FRAM process. • Material flow occurred simultaneously along with the longitudinal and transverse directions at the interlayer. • Thread protrusion significantly increased the material flow in the transverse direction. • Severe plastic deformation resulted in significant grain size reduction for both sides of the interface. • It was experimentally proved that direct contact with no oxide was achieved at the interface, forming a complete metallurgical bonding.

Modeling and optimization of longitudinal-torsional vibration horn with the large tool head

There are problems such as large deviations in resonant frequency and difficulties in selecting the structural parameters of helical slot when designing longitudinal-torsional vibration horn with large tool head (HWLTD) using traditional design theory of horn. Therefore, in this paper, HWLTD was designed integrally, the model of HWLTD was established, longitudinal vibration frequency equation of HWLTD was derived and consequently, the resonant frequency was predicted and optimized. Then, the principle of vibration mode transformation (POVMT) of helical slots was derived. Combined with POVMT and ANSYS simulation analysis, resonant frequency and torsional-longitudinal ratio of longitudinal-torsional vibration of HWLTD were optimized, thereby improving the vibration characteristics of HWLTD. The resonant frequency and vibration effect of HWLTD were tested, and the measurements were agreed with the theoretical design and simulation analysis, which validates the HWLTD model and POVMT. The research provides a reference for the efficient and reliable design of HWLTD in the field of ultrasonic machining.

A new modelling method of material removal profile for electrorheological polishing with a mini annular integrated electrode

This paper addresses the problem of material removal in electrorheological (ER) polishing with a mini annular integrated electrode both theoretically and experimentally. The model of the material removal profile in ER polishing is proposed based on the evaluation of the amount of material removed from the surface along the direction orthogonal to the tool path. Firstly, the electric field distribution around the tool head is deduced theoretically. On this basis, the contact pressure model in the ER polishing area is established. Considering the feed rate and tool spindle speed of ER polishing, the distribution of the relative sliding velocity in the polishing area is modeled. On the basis above, the innovative approach to calculate the material removal profile is developed for the ER tool polishing along a straight path. The model is validated by a series of designed polishing experiments, which demonstrates that the material removal model established in this paper has high prediction accuracy of material removal profile in ER polishing.

Design and simulation of ultrasonic welding system based on TbDyFe alloy

TbDyFe magnetostrictive alloy is prepared by zone melting directional solidification process. The dynamic strain coefficient D33 and B-H curve were obtained at different pressures. The ultrasonic welding system (transducer) based on TbDyFe magnetostrictive material was designed by using transfer matrix method. The finite element simulation method was used to verify the accuracy of the design and determine the size of the tool head.

Intermetallic regulation mechanism of inconel 718/Ti6Al4V composite by novel follow-up ultrasonic assisted laser additive manufacturing

Brittle intermetallic phase is easily formed in titanium alloy/superalloy composite, and this phase can increase the risk of cracking and limit the performance and application of titanium alloy/superalloy gradient materials. In this investigation, 20 wt% Inconel 718 + 80 wt% Ti6Al4V composite is prepared by a novel method of follow-up ultrasonic assisted laser additive manufacturing . Follow-up ultrasonic can keep the relative position of the molten pool and the ultrasonic tool head to guarantee the continuous intensity of the ultrasonic in the molten pool. The high-intensity impact generated by the cavitation effect of the ultrasonic refines and break the chain intermetallic phase (Ti 2 Ni), and increases the content of granular intermetallic phase. In addition, the acoustic streaming effect of ultrasonic promotes the uniform distribution of elements and inhibits the segregation of Ni element. Meanwhile, the ultrasonic vibration promotes the thermal convection of samples and increases the cooling rate to shorten the transition time from β-Ti to Ti 2 Ni. This is beneficial to suppress the generation of Ti 2 Ni. The content of intermetallic phase in the composite is 11.6% without ultrasound, and decreases by 48.3% to 6.0% with the application of 1200 W ultrasonic power, and the distribution uniformity increases by 37.5%. The proportion of intergranular brittle fracture in the mixed fracture of the composite is decreased, and the bending strength increases from 805 MPa without ultrasound to 1047 MPa with 1200 W ultrasonic power, which increased by 30.1%. Through the intervention of the follow-up ultrasonic, the microstructure and properties of the composite are effectively controlled.

IMPROVEMENT OF TECHNOLOGICAL PROCESSES FOR MANUFACTURING GENERATING CONICAL AND HYPOID GEARS

Analysis of existing technological processes has shown that when processing conical and hypoid gears, gear-cutting operations during roughing, semifinishing and finishing have a great influence on the quality of manufacture. The conducted studies of the accuracy of the angular location and radial run out of the cutting edges of the incisors in the incisor heads allowed us to determine their effect on the roughness of the surface of the teeth, indicators of kinematic accuracy and smooth engagement of conical and hypoid gears. Recommendations on the accuracy of the location of the cutters in the tool heads for cutting gears in various industries have been developed.

Study on an Ultrasonic Combined Electro-Machining Control System with Composite Material Experiments

Materials such as stainless steel, cemented carbide, metal matrix composites, etc., usually require combinations of multiple machining, due to their high hardness, high wear resistance, and other mechanical properties. Ultrasonic combined electro-machining (UCEM) is the preferred solution for the efficient machining of high hardness and high toughness products. However, the machining can deviate from the expected values for factors such as physical and chemical complexity and variability, as well as tool head wear, which can make it difficult to keep the process stable, thus leading to a decrease in machining efficiency. To address the above problems, this study constructed and optimized a UCEM detection and control system based on an analysis of the mutual coordination mechanism of each effects of combined machining, and proposed a machining short-circuit avoidance method based on inter-pulse voltage detection that can avoid the irreversible harm caused by the high current generated during electrode short-circuiting in electrolytic machining. This method could be of great value and significance in preventing workpiece burns and improving machining quality.