Thread Form Research Articles

Thread form at the Crystal Palace

This article establishes that the British Standard Whitworth thread form, suggested in 1841 and not adopted as a standard until 1905, was being used at the Crystal Palace sites (1851–1854).

Comparative In Vivo Study of Solid-Type Pure Hyaluronic Acid in Thread Form: Safety and Efficacy Compared to Hyaluronic Acid Filler and Polydioxanone Threads

IntroductionAlthough various products are commonly used for skin rejuvenation, solid-type hyaluronic acid (HA) as an injectable form has not been researched or utilized. This study aimed to demonstrate the safety and efficacy of solid-type HA in thread form, which differs from the conventional gel-type HA commonly used.MethodSolid-type HA threads, conventional HA fillers, and polydioxanone (PDO) threads were inserted into the dorsal subcutaneous layer of mice. Photographs were taken on days 0, 1, 3, and 7, and on day 7, the samples were harvested for histological analysis. Inflammatory reactions and detection of collagen were confirmed through tissue staining, and real-time PCR was conducted to quantify collagen synthesis.ResultsIn the histological analysis, the PDO threads exhibited a greater inflammatory response compared to the HA threads. Masson’s trichrome staining revealed a higher degree of collagen synthesis in the HA thread group compared to the HA filler group. While collagen type 1 expression was significantly higher in the PDO thread group than in the HA thread group, the HA thread group showed higher expression levels of collagen type 3. Furthermore, the PDO thread group demonstrated a statistically significant increase in TGF-β1 compared to the HA group.ConclusionThis in vivo study demonstrated the stable application of solid-type pure HA threads and their potential for inducing collagen production, while also yielding a low inflammatory response. The findings highlight the promising applications of solid-type HA in the field of cosmetic dermatology.No Level AssignedThis journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Application of STEM Technologies on the Example of the Problem of a Thread with a Load

This paper demonstrates the application of STEM technologies using the example of the problem of a thread with a load. As a training problem, parameter finding of a flexible inextensible thread with a load sliding along it, as well as with a fixed load, is considered. A mathematical model of a thread with a load is created without using simplifying assumptions such as a negligibly small mass of the thread, a thread with a small sag or a parabolic approximation of the thread form. When solving the problem, methods of analysis from various branches of mathematics, theoretical mechanics, physics, history of mathematics, as well as various tools of computer mathematical packages (Mathcad), are used. The reasonability of considering such tasks from the perspective of teaching effectiveness for first-year students in engineering as well as in physics and mathematics is proved. Promising educational tasks based on the investigated problem are considered.

Design and Characterization of Mg Alloy Pedicle Screws for Atlantoaxial Fixation

To investigate the feasibility of using absorbable Mg alloy pedicle screws for atlantoaxial dislocation fixation, four types of Mg alloy pedicle screws of different thread forms were designed, and simulation analysis of the pull-out force was performed using the finite element method. Stress and displacement distributions of the atlantoaxial fixation model were obtained. Subsequently, screw samples were prepared using the WE43 Mg alloy for extraction, torsion, and immersion corrosion tests. Finite element analysis results showed that the pull-out forces of triangular, rectangular, trapezoidal, and zigzag thread screws were 552.61, 540.91, 546.4, and 542.74 N, respectively, and the stresses on the screws were 146, 185, 195, and 265 MPa, respectively, when they were pulled out. In other words, the triangular thread screw had the largest pull-out resistance and smallest stress peak. The average corrosion rate of Mg alloy screws in vitro was 0.46 mg·cm−2·day−1. Compared with that before corrosion, the extraction resistance of the corroded screws did not change significantly; however, the torsional strength decreased, but it was still greater than the torque required for screw implantation. It can be concluded that triangular thread Mg alloy pedicle screws have good extraction resistance and mechanical stability and can meet the load-bearing requirements for atlantoaxial dislocation fixation. The degradation of the Mg alloy reduced the mechanical strength of the screws, but the triangularly threaded screws can still maintain their effectiveness.

Long-term fretting corrosion performance of modular head-neck junctions with self-reinforced composite gaskets from PEEK and UHMWPE

Soft gasket-like polymer films may provide multiple advantages in inhibiting fretting corrosion between metal-hard surfaces in total joint implants. Self-reinforced composites (SRC's) made from either poly(ether ether ketone), SRC-PEEK, or ultra high molecular weight polyethylene, SRC-PE, were fabricated and tested to investigate their ability to limit or prevent mechanically assisted corrosion in modular taper devices. Hot compaction was used to create nominally 100 μm thick unidirectional composite gaskets. These gaskets were placed on the trunnions of modular head-neck tapers and seated with 4000 N. One million cycle potentiostatic fretting corrosion tests (3000 N, R = 0.1, 15 Hz, −0.05 V) were employed to assess the ability of these SRCs to reduce or prevent fretting corrosion damage in the modular taper junction. Fretting currents and head-neck micromotion were evaluated. The results of testing, along with pull-off tests and optical and scanning electron microscopic analysis showed that SRC gaskets reduced or eliminated fretting corrosion currents, with the SRC-PEEK performing better than the SRC-PE. Fretting currents were low for SRC's compared to metal-metal tapers. No wear through of the gaskets was noted and minimal wear damage was seen in the SRC-PEEK gaskets. SRC-PE gaskets demonstrated greater deformation and damage compared to the SRC-PEEK gaskets. Pull-off loads for the SRC-PEEK were higher than SRC-PE and not statistically different than the control metal-metal junctions. There was evidence of fatigue cracks forming at the high stress concentration junctions for the SRC-PEEK at the thread form corners of the trunnion, but no loss of integrity was observed. SRC-PEEK gaskets show promise as a method to eliminate modular taper fretting corrosion.

Fracture Analysis of high strength bolt in wind turbine

During the operation of a wind turbine in a wind power generation limited liability company, the bolt connecting the blade and the paddle bearing broke. In order to find out the cause of fracture, a comprehensive test analysis was carried out on the connection bolt between the blade and the variable blade bearing by means of macro morphology analysis, chemical composition analysis, mechanical property testing, microstructure testing and fracture micro-area analysis. Experiments show that: the blade and blade bearing joint bolt fracture: was the main cause of the bolt in the operation process of changing, repeated impact of wind load and the effects of the alternating load blade rotation, along the severe stress concentration of thread form ascend a crack source and extension in fatigue, until the whole fracture failure.

Heat transfer and entropy production evaluation on premixed hydrogen/air-fuelled micro-combustors with internal threads

A micro-combustor with a tailored internal thread is proposed to uniform the wall temperature and improve the second law efficiency of a micro thermophotovoltaic (MTPV) system. The influences of 1) the thread form, 2) the inlet velocity and 3) the nominal diameter on the system’s thermal performances are investigated by performing computational fluid dynamics simulations. Results indicate that the application of the proposed corrugated thread structures can reduce the flame temperature and enhance heat transfer remarkably. The recirculation zone formed in the spiral grooves is conducive to obtaining uniform temperature on the outer combustor surface. Especially when the inlet velocity increases to 5 m/s, the standard deviation of the wall temperature can be maintained below 20 K. In addition, the mean wall temperature and the standard deviation of the wall temperature both increase distinctively with the increase of the nominal diameter. Entropy production is the analysed for the tested combustors with different thread forms. Moreover, the second law efficiency of a triangular thread is above 65%, while the entropy production from the chemical reaction and heat conduction proceses contribute more than 90%. The present work provides a new design of the internal structure for optimizing micro-combustors performances.

The Structural Design of the Threaded Part of the Premium Connection Tubing

The thread form of the premium connection tubing in unconventional gas well is usually API round thread, which has poor connection performance and make-up performance. In response to this problem, this research redesigned the structure of the threaded part of the premium connection tubing, and applied the improved buttress thread of the casing to the tubing to improve the connection performance and make-up performance. The relevant research ideas or results can be used as a reference for subsequent product development.

Semi-analytical torque modeling of Ti-6Al-4V-alloy internal trapezoidal thread extrusion forming with an emphasis on low-frequency torsional vibration

Abstract Conventional cold extrusion is generally considered to be less practical for trapezoidal threads, requiring a relatively large form tapping torque. The machining of it is always based on cutting, but the actual demands of high strength and long life have brought this process to its limits. These requirements drove the present work, which proposes a new process for the fabrication of a Ti-6Al-4V-alloy trapezoidal thread using low-frequency torsional vibration extrusion (LTVE) through a forming tap. A semi-analytical model of torsional vibration extrusion with friction was established by solving the problem of mechanical friction and slip-line field. The influence of low-frequency torsional vibration on the form tapping torque was studied, and the total amounts were determined quantitatively. The conclusion shows that the total tapping torque was composed of the positive pressure load and the friction load on the forming tap. The friction load was generated by the tool/workpiece friction, which is the largest component, accounting for more than 90 %. The introduction of vibration can reduce the friction in the thread form tapping so as to obtain high rheological properties, which is applicable for the low-frequency stage. Finally, a mechanical LTVE tapping excitation device was proposed based on this process method, and an experimental prototype that can meet the requirements of titanium alloy trapezoidal thread machining was developed. Experimental verification indicated that the LTVE forming process had reduced the total form tapping torque. It also proved the method’s overall reliability and effectiveness and the underlying insights needed to guide the thread manufacturing.

Research on Laser Thread Form Bending of Stainless Steel Tube

Compared to traditional bending methods, laser bending can yield products with better shapes and higher quality using the simpler equipment. In this paper, the mechanism of Laser-assisted tube bending is elaborated, and then the influence of processing parameters (including laser power, scanning speed, spot diameter, and scanning times) on the bending angle is studied with both the finite element method and experiments. The bending angle increases with an increase of laser power and spot diameter and with a decrease in the scanning speed. Three-dimensional (3D) thread form bending can be achieved by planning the optimal route, scanning parameters, and the number of laser scans. In contrast to the desired thread diameter of 20 mm and thread pitch of 180 mm, the resulting thread of the stainless steel tube is close to the target shape with errors of 3% for thread diameter and 2.5% for thread pitch, which are both in an acceptable range and thus verify the validity of the parameters selection and route planning method.

Ideal length of thread forms for screws used in screw fixation of nondisplaced femoral neck fractures

BackgroundIt is common practice when placing cannulated screws within the femoral head when treating femoral neck fractures to avoid the thread-forms from crossing the fracture line. Despite the widespread use of cannulated screws in internal fixation of femoral neck fractures, there is no study to our knowledge that describes the ideal length of thread-forms. PurposeThe purpose of this study is to determine the thread length that will maximize purchase within the femoral head while minimizing risk of crossing the fracture line. Additional analysis was conducted to identify factors associated with the maximal possible length of treads in minimally and non-displaced femoral neck fractures. MethodsWe performed a retrospective study of all patients treated for a minimally or non-displaced femoral neck fracture from April 1, 2004 through December 31, 2017. Only patients who had received a pre-operative CT or MRI scan were included. Fixation was then templated using radiographs and the distance from the subchondral bone to the fracture line was then measured. ResultsThe study included 127 patients. The average estimated length of lag screw threads was 33.2 ± 6.67 mm, with lower quartile of 29.1 mm and higher quartile of 37.2 mm. The median was 32.0 mm and most frequently encountered estimate was 29 mm. Estimated lag screw size did not differ significantly based on age or BMI, but both height (p < 0.001) and race (0.04) were positively correlated with estimated lag screw size and males had longer measurements compared to females, 37.2 ± 7.0 mm vs 31.4 ± 5.7 mm (p < 0.001), respectively. ConclusionIn conclusion, we propose an additional lag screw thread form with length 26.0 mm to capture 90% of femoral neck fractures.

Some effects of tool geometric features on friction stir weld response parameters

ABSTRACTPin geometries (shape, dimensions, and surface features) have significant effects on friction stir welding, dictating, to some extent, the material flow which in turn affects process variables and joint quality. In this paper, volumetric defect content and process response variables (in-plane forces, torque, power, and temperature) as a function of pin thread forms and features (thread/flat/flute) on mildly tapered conical pins were examined in AA6061-T6 for a range of welding parameters. The coarser thread pitch with different pin features performed better for producing good quality welds compared to finer threaded pins. Forge force requirements can be minimised using counter-flow flutes in threaded pin. Variations of nugget geometry, torque, power, and temperature were reported to correlate their dependence on pin features.

Numerical analysis of heat transfer to water flowing in rifled tubes at supercritical pressures

Heat transfer to supercritical water flowing in vertical upward rifled tubes are studied. The shear stress transport turbulence model was applied to numerical analysis and was validated with experimental data. Results of numerical simulation showed that the present model could provide a satisfactory prediction with enough accuracy. According to the results, inner wall temperature varies periodically in circumferential direction. It peaks at the intersection of the root and the leeward side and reaches the minimum at the intersection of the crest and the windward side. The circumferential distribution of inner wall heat flux is similar to that of the inner wall temperature. However, at the root the variation of inner wall heat flux is contrast to that of inner wall temperature and the rotational flow caused by the screw thread may contribute to this result. Heat transfer enhancement occurs where the boundary layer is filled with fluid of large specific heat and the effect of kinetic energy is not dominant. The structural parameters of screw thread affect heat transfer in rifled tubes. The increase of thread height significantly improved the performance of heat transfer, but the effects of pitch, lead angle and thread form are negligible.

3D Finite Elements Modeling of the Interfacial Stresses Bone/Dental Implant - Effects of the Geometric Parameters

A successful osseointegration involves the simultaneous optimization of the primary stability of the implant and the minimization of interfacial stresses bone - implant. In this context, the modeling of these stresses reports a great interest for researchers in last decades.The aim of this work is to study the effects of geometric parameters of a new model of titanium dental implant on the evolution of interfacial stresses bone /implant. For this, a dental implant of the second premolar in the lower jaw was considered, with different diameters, thread pitches and different thread forms. The profile of the interfacial stresses was presented for each case study, the results show a great similarity in the areas concerned, cortical bone, threaded region and cancellous bone, with the results obtained in the literature for other types of geometries.

A methodology for helical mill-grinding of tiny internal threads made of hard brittle materials

This study proposes a methodology for helical mill-grinding of tiny internal threads made of hard brittle materials such as SiCp/Al composites. The methodology uses the helical mill-grinding method incorporating with a diamond form-grinding wheel. A mathematical model is established to predict thread form errors and provide a rational range of wheel parameters, such as variation of tool profile angle Δα and ratio of the wheel diameter to the thread major diameter η. Based on the methodology, a grinding wheel is developed for processing the M2 internal threads in a validation experiment. The study demonstrates that an M2 internal thread made of the SiCp/Al composite of 45% SiC volume fraction is successfully machined in 5 min with pitch error <0.08% and angle error <0.3%. The thread profile on the pitch diameter is within the axial equivalent tolerance zone (0–0.016 mm), which indicates that the thread precision reaches the H4 level.

Load distribution of planetary roller screw mechanism and its improvement approach

A model of load distribution over threads of planetary roller screw mechanism (PRSM) is developed according to the relationships of deformation compatibility and force equilibrium. In order to make the applied load of PRSM uniformly distributed over threads, an improvement approach is proposed, in which the parameters of thread form of roller and nut are redesigned, and the contact conditions of roller with screw and nut are changed to compensate the axial accumulative deformation of shaft sections of screw and nut. A typical planetary roller screw mechanism is taken as example to analyze the load distribution, and the effects of installation configurations, load conditions and thread form parameters on load distribution are studied. Furthermore, the improvement approach is applied to the PRSM, and it is proved to be beneficial to reach uniform load distribution over threads.

Advanced Technologies and Solutions for Challenging Drilling Applications

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 170566, ’Advanced Technologies and Practical Solutions for Challenging Drilling Applications,’ by M.J. Jellison, SPE, NOV Grant Prideco, and A. Chan, Workstrings International, prepared for the 2014 SPE Asia Pacific Drilling Technology Conference and Exhibition, Bangkok, Thailand, 25-27 August. The paper has not been peer reviewed. This paper provides a review of recent technology advancements and addresses practical considerations associated with drillpipe and drillstem components for extreme drilling applications. Recent developments and enhancements in these connection designs, including new higher-strength materials, advanced thread forms, and associated improvements in torsional strength and fatigue performance, are presented. The paper discusses the engineering solutions implemented to overcome the high forces, slip-crushing concerns, and material-strength and toughness considerations for these critical applications. Third-Generation Double-Shoulder Connection Since the introduction of the second-generation double-shoulder connection (DSC), the industry trend has continued toward deeper and longer-reach wells, which has dictated the need for drillpipe connections with enhanced mechanical and dimensional characteristics coupled with improved makeup/ breakout speeds. Consequently, a project was commissioned to design, analyze, laboratory test, and field trial the industry’s first third-generation DSC. A key objective of the project was to improve connection makeup/breakout speeds significantly. Mechanical and hydraulic gains were also dictated on the basis of the industry’s trend toward deeper and longer-reach wells.

Production of microbubbles from axisymmetric flow focusing in the jetting regime for moderate Reynolds numbers.

We analyze both experimentally and numerically the formation of microbubbles in the jetting regime reached when a moderately viscous liquid stream focuses a gaseous meniscus inside a converging micronozzle. If the total (stagnation) pressure of the injected gas current is fixed upstream, then there are certain conditions on which a quasisteady gas meniscus forms. The meniscus tip is sharpened by the liquid stream down to the gas molecular scale. On the other side, monodisperse collections of microbubbles can be steadily produced in the jetting regime if the feeding capillary is appropriately located inside the nozzle. In this case, the microbubble size depends on the feeding capillary position. The numerical simulations for an imposed gas flow rate show that a recirculation cell appears in the gaseous meniscus for low enough values of that parameter. The experiments allow one to conclude that the bubble pinch-off comprises two phases: (i) a stretching motion of the precursor jet where the neck radius versus the time before the pinch essentially follows a potential law, and (ii) a final stage where a very thin and slender gaseous thread forms and eventually breaks apart into a number of micron-sized bubbles. Because of the difference between the free surface and core velocities, the gaseous jet breakage differs substantially from that of liquid capillary jets and gives rise to bubbles with diameters much larger than those expected from the Rayleigh-type capillary instability. The dependency of the bubble diameter upon the flow-rate ratio agrees with the scaling law derived by A. M. Gañán-Calvo [Phys. Rev. E 69, 027301 (2004)], although a slight influence of the Reynolds number can be observed in our experiments.

Effect of Tool Pin Thread Forms on Friction Stir Weldability of Different Aluminum Alloys

The primary objective of this study is to investigate parametric effects of pin features on material flow and friction stir weldability of two different aluminum alloys. A series of bead on plate friction stir welds were made on two different aluminum alloys (AA 7050 and AA6061) with cylindrical tool pin having four thread pitches (1.02mm, 1.41mm, 2.12mm & 3.18mm) including smooth/unthreaded pin attached to an unvarying single scrolled shoulder geometry. Welds were performed under a range of process parameters (welding & rotational speed). It was observed that thread forms are obviously beneficial for improving tool performance and reducing in-plane reactions (X & Y forces) forces on tool. Wormhole defects in the weld nugget were eliminated or minimized by employing threaded pins as a consequence of effective material transportation near the weld root. Tool pins having intermediate thread pitches (1.41mm and 2.12mm) perform better than either extreme over the range of attempted parameters. Defects are far more prevalent in 7050 welds than in 6061. In-plane reaction forces on pin are significantly larger in AA7050 welds than in AA 6061 and torque- peak temperature values are of similar order in both welded materials.

Investigation of the effects of adhesion promoters on the adhesion properties of rubber/steel cord by a new testing technique

ABSTRACTThe effects of adhesion promoters, cobalt decanoate and PN759 (modified resorcinol) on the static and dynamic adhesion properties of rubber/steel cord in a carcass recipe are examined. A new testing method with special rubber/steel cord specimens was developed. It was found that cobalt decanoate could improve the static adhesion and favored the dynamic adhesion of rubber/steel cord so that adhesive failure mainly occurred in rubber phase. A resorcinol‐formaldehyde‐silica promoting system was deleterious to adhesion stability, but improved initial adhesion strength. PN759 improved the dynamic mechanical properties compared with resorcinol for the carcass vulcanizates at strains less than 10%. PN759 instead of resorcinol slightly improved the static and dynamic adhesion and the probability that adhesion failure occurred in the interphase was similar to that occurring in the rubber phase. The dynamic “pull‐out forces” for samples with 1.0 phr cobalt decanoate first increased and then decreased with the increase in the number of fatigue cycles and reached a maximum at 100,000 fatigue cycles. The covered rubber on the “pulled‐out” cord after fatigue appeared to form a screw thread form and the greater pull‐out force corresponded to more uniform and narrower screw threads. SEM images indicated that un‐dispersed filler agglomerates could be the initiating factor for adhesive failure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39460.