Force Of Thread Research Articles

Influence of Process Parameters on the Height and Performance of Magnesium Alloy AZ91D Internal Thread by Assisted Heating Extrusion.

The quality of threaded connection is an important factor affecting the service life of equipment. Extruded thread has stronger mechanical properties than traditional cutting thread. The forming of magnesium alloy AZ91D internal thread by electromagnetic induction heating assisted extrusion is a new processing method. In this work, on the basis of this process, the height and performance of internal thread are selected as the evaluation index, and the response surface method is used to analyze the influence of the process parameters on the internal thread performance. The range of process parameters (auxiliary heating temperature, hole diameter, machine tool speed) is determined by slip line and empirical method, the test data are simulated, modeled and compared with the response surface analysis method, and the best mathematical model is selected to establish the regression model, the three-dimensional response surface curve of tooth height rate and maximum tensile force is obtained. Through simulation and prediction, it is found that the hole diameter and auxiliary heating temperature have significant influence on the tooth height rate and maximum tensile force of internal thread, and the order is that the hole diameter is larger than the auxiliary heating temperature than the machine tool speed. The research results show that the measured value of tooth height rate and maximum tensile force are close to the predicted value, and the errors are 1.8% and 2.7% respectively, and the model fits well. The better forming process parameters are as follows: auxiliary heating temperature to be 220 °C, hole diameter to be 11.35 mm, machine tool speed to be200 r/min. under this parameter, the tooth height rate and maximum tensile force to be 89.056% and 38.824 KN. At the same time, it is found that with the increase of thread height, the maximum tensile force of thread is also increasing, and the thread height affects the performance of thread. Finally, the optimal process parameters are obtained by response surface method, which improves the tensile properties of extruded internal threads.

Robotic Threading from a Gel-like Substance Based on Impedance Control With Force Tracking

Gel-like matter is used extensively in a wide range of application fields including industrial applications such as the manufactory and assembly of garment and footwear products, soft macro/micro-robotics, medical diagnostics, and drug delivery. However, the manipulation of gel-like matter is very challenging, due to its high deformability, high viscosity, and fast phase changing. In this letter, we propose a novel biomimetic robotic fiber threading approach based on impedance control with force tracking. The highly integrated approach can control the impedance of the fiber during both threading and solidification of the fiber and characterize the mechanical properties of the fabricated fibers in the very same setup without changing parts. The impedance control method has also been adapted in this letter by adding a real-time estimator for continuously estimating the stiffness of the threading force for highly accurate control. The resulted fibers using the proposed approach demonstrates higher performances in all terms of toughness, stiffness, elongation and strength, compared to the traditional velocity controlled fiber fabrication approach.

Matrix Vaginal Rings for Female Dogs-Effect of Altering Dimensions on Mechanical Properties and Dissolution Characteristics, and In vivo Safety Study.

The vaginal rings research is almost exclusively focused on rings for human medicine, although the dosage form offers improvement of therapeutic effect in other mammals as well. This contribution studied an effect of varying dimension parameters (diameter 20, 30 or 40mm; height 3, 4 or 5mm; width of annulus 5, 7.5 or 10mm) on mechanical properties and dissolution behaviour of silicone vaginal rings with constant drug amount, intended for use in dogs. Results showed that altering dimensions influenced mechanical properties (compressive force, tensile strength and resistance of removal thread), in vitro drug release and water uptake. The removal thread resistance was increasing with increasing height and width. Compression force was higher for the rings with smaller diameter. The total drug release was increasing with decreasing height and rising diameter, surface area and water uptake during dissolution test. The initial dissolution rate was slower for the rings with higher width. As the best candidate for use in model dog subjects, the ring with 30mm diameter, 3mm height and 7.5mm width was found. These drug-free vaginal rings were further tested in in vivo safety study. The results did not show any major deviation from the physiological conditions. Graphical abstract.

Verification of relationship between tension and grip force of binding thread in finger / binding interlocking robot hand

Verification of relationship between tension and grip force of binding thread in finger / binding interlocking robot hand

3D Woven Near‐Net‐Shape Preforms for Composite Structures

Weaving of near‐net‐shape spacer structures is an efficient way to produce preforms for fiber‐reinforced composites. The preforms are woven using non‐crimp fiber arrangement in warp and weft directions. For getting a better insight into the weaving process as well as to analyze warp thread forces, a simulation model has been developed. This enables calculations under variation of machine and process parameters to minimize warp thread forces. The aim in conjunction with this is downsizing the tensile stress of threads for reducing fiber damage. The high potential of the non‐crimp fiber arrangement is demonstrated in consolidated 2D composite sheets and 3D spacer composites.

소재와 나사산 변화에 따른 정밀나사의 체결력 향상에 관한 연구

In this study, we compare the performance of the screw through the Clamping force of the test materials to change shape and structure, one of the ways to maintain and improve the engaging force to cope with the miniaturization of the fastener threads are further thinner and lighter precision way that can improve the fastening force of the screw results were as follows. The clamping force according to the materials was 7.57Nㆍcm in SUS XM7 and SWCH18A was 5.97 Nㆍcm. This result was to be found to average 13.5% high in the Clamping force of SUS XM7 materials. In the case of the clamping force of the screw thread shape change, the clamping force of symmetrical and asymmetrical thread was 6.78 Nㆍcm and 7.57 Nㆍcm. The clamping force of the asymmetrical thread showed an average high of 11.6%.

Hydrodynamic slip on DNA observed by optical tweezers-controlled translocation experiments with solid-state and lipid-coated nanopores.

We use optical tweezers to investigate the threading force on a single dsDNA molecule inside silicon-nitride nanopores between 6 and 70 nm in diameter, as well as lipid-coated solid-state nanopores. We observe a strong increase of the threading force for decreasing nanopore size that can be attributed to a significant reduction in the electroosmotic flow (EOF), which opposes the electrophoresis. Additionally, we show that the EOF can also be reduced by coating the nanopore wall with an electrically neutral lipid bilayer, resulting in an 85% increase in threading force. All experimental findings can be described by a quantitative theoretical model that incorporates a hydrodynamic slip effect on the DNA surface with a slip length of 0.5 nm.

Keys to minimizing the risk of spinal cord trauma during a lumbar approach to thoracic epidural

Thoracic epidurals provide effective analgesia for thoracic or upper abdominal procedures for both adult and pediatric patients; however, using a thoracic approach to place an epidural catheter is not without risk as it requires needle placement immediately posterior to the spinal cord. Consequently, some clinicians prefer to use a lumbar approach (caudal approach in pediatric cases), or if unsuccessful at a thoracic level, they may thread the epidural catheter cephalad from that point. This issue of the Journal features an interesting study by Gamble et al. in which the authors used a porcine model to address the safety of threading an epidural catheter via a lumbar approach. In their study, the authors show that styletted stimulating thoracic epidural catheters can be advanced in a predictable manner to target thoracic myotomes using a lumbar approach. However, damage to the spinal cord was observed in several animals. It is important to point out that, in humans, such perturbing findings are probably limited to high lumbar approaches (i.e., above L2-L3). This is partly because the human adult spinal cord, unlike the porcine model used in the Gamble et al. study, typically ends at approximately the L1-L2 level. Thus, if needle entry occurs either at or below the L2-L3 level, the risk of direct blunt trauma caused by the initial threading of the catheter from the needle tip is minimized. Nevertheless, the results of Gamble et al.’s study clearly show the risks involved when a catheter is advanced directly towards the spinal cord, as in thoracic and high lumbar approaches. Several key factors influence the risk and potential for spinal cord damage during these approaches, including the angle of catheter insertion, catheter stiffness, and applied force. To address this issue, the relationship between these three factors must be considered. Force must be applied to advance the catheter to its desired target myotome level. This threading force is the total applied force needed to insert the catheter through the Tuohy needle into the epidural space. Threading force itself involves two component forces that must be considered during catheter insertion: a bending force, needed to advance the catheter out of the needle, and a parallel force, needed to thread the catheter cranially past any obstacle within the epidural space (Fig. 1). Assuming there is minimal obstruction along the spinal cord, the initial total threading force is then directly related to the bending force. This is shown in Gamble et al.’s experiment where, in most animals, difficulty was experienced in advancing the catheter beyond the needle tip. The perpendicular angle of insertion used by the authors suggests the need for considerable bending force to advance the catheter out of the needle. Furthermore, the authors speculate that catheter stiffness and the presence of the stylet added to the difficulties in initial catheter advancement. Thus, the bending force required to advance the catheter out of the needle is influenced by two key factors: angulation of the needle and catheter stiffness (i.e., styletted or not). To show this relationship, we used a simple in vitro setup to demonstrate the peak (kilogram) force generated when threading a styletted catheter at various needle angles (Figure). As shown, the peak force increases dramatically as the angulation of the needle approaches 0 (i.e., perpendicular) relative to the surface of the force gauge transducer. With an insertion perpendicular to the plane of the back (i.e., no angulation), these results suggest that the B. C. H. Tsui, MD (&) Department of Anesthesiology and Pain Medicine, University of Alberta, 8-120 Clinical Sciences Building, Edmonton, AB T6G 2G3, Canada e-mail: btsui@ualberta.ca

Mono- versus polyaxial locking plates in distal femur fractures: a prospective randomized multicentre clinical trial

Treatment of complex fractures of the distal femur utilizing monoaxial locking plates (e.g. Less Invasive Stabilisation System, LISS®, Synthes) is considered to be superior to conventional plating systems. Due to the limitation that the thread forces the screw into pre-determined positions, modifications have been made to allow screw positioning within a range of 30° (Non Contact Bridging, NCB®-DF, Zimmer). For the first time, this multicenter prospective randomized clinical trial (RCT) investigates the outcome of LISS® vs. NCB®-DF treatment following complex fractures of the distal femur. Since June 2008, 27 patients with a fracture of the distal femur (AO ASIF 33-A-C and periprosthetic fractures) were enrolled in this study by four university trauma centres in southern Germany. Clinical (e.g. range of motion, Oxford knee score, Tegner score) and radiological (e.g. axis deviation, secondary loss of realignment) follow-ups were conducted one and six weeks, as well as three, six, and 12 months after the operation. This study comprises data of 27 patients (8 male, 19 female; 15 NCB®-DF, 12 LISS®). Polyaxial osteosynthesis using the NCB® system tended to result in better functional knee scores and a higher range of motion. Interestingly, fracture union tended to be more rapid using the polyaxial plating system. We present the analysis of a multicenter prospective RCT to compare the monoaxial LISS® vs. the polyaxial NCB®-DF treatment following complex fractures of the distal femur. NCB®-DF treatment tended to result in better functional and radiological outcomes than LISS® treatment. Level I.

New solutions for the manufacturing of spacer preforms for thermoplastic textile-reinforced lightweight structures

The novel woven spacer fabrics consist of upper and lower layers which are connected through internal crosslinks. The aim is to weave spacer fabrics with woven crosslinks in a single production step as near net shape sandwich preforms. By this way reproducible and automated manufacturing of sandwich preforms for composites are realized. The paper deals at first with the conception of a new weaving and take-up technology of complete spacer fabrics without subsequent textile assembly processes. Afterwards, the special technology is described, and finally the paper deals with a simulation model for the prediction of dynamic warp thread forces in order to minimize fiber damage during weaving process.

An Experimental Study on Cutting Forces in the Threading and the Side Cut Turning With Coated and Uncoated Grades

The objective of this study is to obtain the cutting force components on the threading insert. The cutting force data used in the analysis are measured by a three-dimensional dynamic force dynamometer. The AISI 4140 and AISI 4340 low alloy steels are selected for the experiment on the threading and the side cut turning. The inserts used for testing is the TiAlN coated and uncoated grades. LT22NR35ISO type insert is used in the experiment. During the experiments, no cutting fluid and a constant spindle speed is used. The thread pitch and the depth of cut were kept fixed at 3.5 mm and 0.05 mm for the radial feed per pass, respectively. The study emphasizes on the effects on the workpiece material and the cutting tool grade of the cutting force components that occur during the threading. Also, these results are compared with the findings that are obtained during the side cut turning. It is determined that the measured primary cutting and radial forces during the threading are approximately three times bigger than those during the side cut turning, although feed forces during the threading are approximately 30 times lower compared with the side cut turning. The TiAlN coated WC/Co grade shows the best performance with respect to the cutting force components. The specific cutting forces are determined in order to understand the interference of chips that occur during the threading. With the increase in the cumulative radial feed, the corresponding specific cutting forces become higher. It is reasoned that the difference in the specific cutting forces results from the alteration of the interference of the flowing chips. The specific cutting forces decrease in the beginning of the threading and then increases with the cumulative radial feed. The results show that the interference of the chip flow influences the threading force components to a very large extent.

Magnetostrictive Bilayer Sensor for Micro Torque Measurements

The paper reports the practical application of novel, highly bending sensitive bilayer sensors, of about 100 μm in thickness, which consist of a magnetostrictive layer and a non-magnetic counter layer. Bending yields stress in the magnetostrictive layer, the sensitivity being adjustable by the composition of the counter layer. Extremely high sensitivities proved to yield effective applications for the detection of ultra-low values of torque M (order of 10 Nm) as being typical for micro-motors. Torque measurements were performed utilizing the cable brake principle. By means of a thin thread wound around the motor shaft, increasing load and thus decreasing rotational speed n was attained by continuous displacement of the left end of the thread. The thread was fixed at two calibrated bilayer sensors which detected the thread forces F1 and F2. The torque was calculated as M = (F1-F2) ·(Rd+r), with Rd the radius of the shaft and r the radius of the thread. By measuring the speed by means of a laser tachometer the dependence of torque on rotational speed was evaluated. The compact and low cost bilayers proved to act as ultra-low-force sensors with highest sensitivity, enabling rapid and effective torque tests of micro-motors.

Deconstructing protein threading force fields

Deconstructing protein threading force fields

Study of the tensile force of thread in relation to its pre‐tension

The perfect interlacing of needle and bobbin thread in the stitch formation process and seam appearance depends first of all on correct pre‐tension of the tension regulator. Changes in the pre‐tension settings also have a direct influence on the tensile force during the sewing process. This contribution presents the influence of pre‐tension in a defined area on the tensile force in important phases of the stitch formation process. In addition the influence of the stitch velocity on tensile force was investigated. On the basis of statistic analysis it was ascertained in which pre‐tension area and stitch velocity the significant differences between tensile forces occurred.