Press-fit Connections Research Articles

An Investigation of Increased Power Transmission Capabilities of Elastic–Plastic-Designed Press–Fit Connections Using a Detachable Joining Device

An Investigation of Increased Power Transmission Capabilities of Elastic–Plastic-Designed Press–Fit Connections Using a Detachable Joining Device

Cross-Contamination of Ignitable Liquid Residues on Wildfire Debris—Effects of Packaging and Storage on Detection and Characterization

Producing defensible data for legal proceedings requires strict monitoring of sample integrity. In fire debris analysis, various approved packaging and storage solutions are designed to achieve this by preventing cross-contamination. This study examines the efficiency of current practices at preventing cross-contamination in the presence of a sample matrix (charred wood) via analysis by comprehensive multidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-ToF MS). The transfer of ignitable liquid residue (ILR) was assessed by comparing percentages of the target ILR area relative to the total chromatogram area and applying chemometric tools developed to detect cross-contamination. All practices reduced cross-contamination in comparison to faulty packaging. Individual practices varied in their performance. Nylon-based packaging performed best, whereas commercial polyethylene-based packaging performed worst due to interfering compounds emitted from the material and sealing mechanism. Heat-sealing was the best sealing mechanism when applied correctly, followed by press-fit connections, and lastly, adhesive sealing. Refrigerated storage offered several advantages, with elevated impact for polyethylene-based packaging and adhesive sealing mechanisms. Triple-layer packaging practices did not show significant benefits over double-layers. The recommended packaging approach based on these findings is mixed-material packaging (metal quart can in a heat-sealed nylon bag), offering advanced prevention of cross-contamination and practical advantages with continued refrigeration during transport.

Investigations on design limits and improved material utilization of press-fit connections using elastic-plastic design

Today, there are a number of analytical and numerical calculation methods for the elastic-plastic design of press-fit connections. However, these are largely constrained by their restriction to elastic-ideal-plastic material behavior. In addition, recommendations for limiting the plasticized hub cross section that have been provided to date do not exploit the full potential of the materials, with the result that opportunities for lightweight design and improved transmission capacity have remained unused so far. Yet, no experimental validations exist to this end, which is why the existing design method could not be validated until today. In addition, there is still a lack of research on how to evaluate the potential for increasing the force and torque transmission under consideration of the strain hardening of the material during plastic deformation. The lack of knowledge today prevents a targeted design and thereby the industrial application of this type of connection; the transmission capacity and lightweight design potentials have thus remained unused until now (Kröger and Binz, 2020). This article presents the actual design and joining limits of hubs made of EN AW-5083 (AlMg4,5Mn), which were determined as part of an Industrial Collective Research (IGF) project. This allows the hub materials to be better utilized, which leads to a reduction in mass and/or an increase in the force and torque transmission. In addition, the experimental validation of the numerical investigations helps to establish the design method in industrial practice.

The Click-On gamma probe, a second-generation tethered robotic gamma probe that improves dexterity and surgical decision-making

PurposeDecision-making and dexterity, features that become increasingly relevant in (robot-assisted) minimally invasive surgery, are considered key components in improving the surgical accuracy. Recently, DROP-IN gamma probes were introduced to facilitate radioguided robotic surgery. We now studied if robotic DROP-IN radioguidance can be further improved using tethered Click-On designs that integrate gamma detection onto the robotic instruments themselves.MethodsUsing computer-assisted drawing software, 3D printing and precision machining, we created a Click-On probe containing two press-fit connections and an additional grasping moiety for a ProGrasp instrument combined with fiducials that could be video tracked using the Firefly laparoscope. Using a dexterity phantom, the duration of the specific tasks and the path traveled could be compared between use of the Click-On or DROP-IN probe. To study the impact on surgical decision-making, we performed a blinded study, in porcine models, wherein surgeons had to identify a hidden 57Co-source using either palpation or Click-On radioguidance.ResultsWhen assembled onto a ProGrasp instrument, while preserving grasping function and rotational freedom, the fully functional prototype could be inserted through a 12-mm trocar. In dexterity assessments, the Click-On provided a 40% reduction in movements compared to the DROP-IN, which converted into a reduction in time, path length, and increase in straightness index. Radioguidance also improved decision-making; task-completion rate increased by 60%, procedural time was reduced, and movements became more focused.ConclusionThe Click-On gamma probe provides a step toward full integration of radioguidance in minimal invasive surgery. The value of this concept was underlined by its impact on surgical dexterity and decision-making.

Компьютерное моделирование прессового соединения

The design of modern technology is associated with increased requirements for strength and manufacturability. Press fit connections of small size parts can withstand significant workloads, so they are widely used in mechanisms and machines. Traditionally, the calculation of press fit connections is performed according to classical formulas using a large amount of reference data. The calculations use standard recommendations that make it easier to obtain solutions with a minimum investment of time. However, the time saving limits the search to a few joints, which are not always the best in some indicators. Modeling press fit joints with different combinations of parameters leads to the formation of hundreds of potential joints. To check their performance, it is necessary to use modern computing facilities. The computer has almost unlimited possibilities for computing speed and storing arrays of information. Simulation of press fit connections on a computer allows obtaining regression metamodels, accessing the statistical significance of parameters, and determining the area of workable connections. It becomes possible to optimize the design of the joint in terms of strength, weight and assembly technology. The system for calculating and statistical analysis of press fit connections has been developed on the basis of existing standards. A program has been developed providing the joints formation and verification with an assessment of their suitability for the specified requirements.

Sliding speed effect in press-fit connection using Finite Element Analysis

Solderless press-fit contacts in power module packages are now gaining more attention in the automotive industry especially in hybrid electric vehicles because of the Restriction of Hazardous Substances (RoHS) directive to eliminate lead-based connections. The production of press-fit assembly is also faster, more convenient, safer, and cheaper than soldered connections. In this paper, the effect of insertion speed of pin to the press-in force as well as the pull-out speed to the retention force was investigated using finite element analysis. An eye-of-the-needle (EON) shape compliant pin with general dimensions was adapted and a transient structural analysis in ANSYS mechanical was used to add and vary the speed of the press-fit pin geometry. Four simulations were conducted with different speeds. The results obtained by FEA show that the speed when kept at constant has no significant effect both on the press-in and retention force. However, when the speed changes due to acceleration, the press-in and pull-out force are both affected.

Change in Contact Resistance and Interfacial Microstructure at Press–Fit Connection Under Large Current Loading

Change in Contact Resistance and Interfacial Microstructure at Press–Fit Connection Under Large Current Loading

Mechanical behavior investigation of press-fit connector based on finite element simulation and its reliability evaluation

As the successor of soldering, the press-fit electrical connection is more and more widely used on account of a number of advantages, such as fast assembly. However, in practice, some contact failures were found. Most of the failures are related to the force which the structure bears. Because of complex elastic-plastic deformation characteristic, analyzing the mechanical behavior of the press-fit is challenging. Some studies have been done on the assembly force behavior of the press-fit such as press in force. However, the stress behavior on the assembly is not clearly studied. In this paper, the mechanical behavior of a typical press-fit connector named as eye of needle (EON) was investigated based on finite element (FE) simulation. Firstly, FE models were established and verified. Then, basing on model analysis, the mechanical behaviors (mechanical stress, thermal stress, and contact force) of the EON were obtained, which makes it clear that the relationships between the EON's structural parameters and its work conditions. Finally, the long-term reliability of the EON connector under the stress relaxation and the thermal fatigue was evaluated, respectively. The FE models here are effective on analyzing the press-fit mechanical behavior, which can be adopted to help design and manufacture.

Расчетное прогнозирование влияния технологических условий обработки на эксплуатационные свойства деталей машин

The paper reports theoretical dependences defining a correlation of technological processing conditions (cutting modes, tool tip geometry, properties of worked and tool materials), quality parameters of a surface layer (surface roughness, degree and depth of cold work, residual stresses) and performance properties of machinery (fatigue resistance, wear-resistance, contact rigidity, press-fit connection strength) which can be used in a team-work of a designer and a technologist at simultaneous technological pre-production.

Interface Reaction and Contact Stability of High-Current Press-fit Connection

Interface Reaction and Contact Stability of High-Current Press-fit Connection

Laser surface texturing of stainless steel 316L cylindrical pins for interference fit applications

This study is focused on the development of a novel method for designing high-end interference fit fasteners. In this work, a new surface laser treatment process was utilized to enable enhanced usability and bond strength control of press-fit connections. Cylindrical 10mm diameter pins of 316L were textured over a 10mm length using a pulsed CO2 laser beam focused one millimeter below the surface, with the thermal energy adjusted to bring the surface to just above the melting point of the metal. The pin surface morphology and dimensions were precisely controlled by controlling the laser processing parameters specifically the laser beam power, the pulse repetition frequency, and the overlap between scan tracks. The pin was inserted into a hub hole diameter of 10.05±0.003mm and pull out joint bond strengths were examined. The results of this study showed that surface thus altered provided improved control of the bond strength which is a particular novelty of this new interference fit joining method. Surface roughness, Ra, from 40 to 160μm, melt pool depths from 0.4 to 1.7mm, increases in the pin outer diameter from 0.5 to 1.1mm, and pull out forces of up to 7.51kN were achieved. The bond joint was found to re-grip before final failure providing a more secure joint and increased safety. This joining method allows for the possibility of joining different materials. The pulse repetition frequency was measured to be the most significant processing parameter for control of the resulting mechanical properties and the bond strength with a clear inverse relationship.

Токонесущая способность непаяных соединений типа Press-Fit

Токонесущая способность непаяных соединений типа Press-Fit

Large-diameter total hip arthroplasty modular heads require greater assembly forces for initial stability

ObjectivesModular junctions are ubiquitous in contemporary hip arthroplasty. The head-trunnion junction is implicated in the failure of large diameter metal-on-metal (MoM) hips which are the currently the topic of one the largest legal actions in the history of orthopaedics (estimated costs are stated to exceed $4 billion). Several factors are known to influence the strength of these press-fit modular connections. However, the influence of different head sizes has not previously been investigated. The aim of the study was to establish whether the choice of head size influences the initial strength of the trunnion-head connection.Materials and MethodsTi-6Al-4V trunnions (n = 60) and two different sizes of cobalt-chromium (Co-Cr) heads (28 mm and 36 mm; 30 of each size) were used in the study. Three different levels of assembly force were considered: 4 kN; 5 kN; and 6 kN (n = 10 each). The strength of the press-fit connection was subsequently evaluated by measuring the pull-off force required to break the connection. The statistical differences in pull-off force were examined using a Kruskal–Wallis test and two-sample Mann–Whitney U test. Finite element and analytical models were developed to understand the reasons for the experimentally observed differences.Results36 mm diameter heads had significantly lower pull-off forces than 28 mm heads when impacted at 4 kN and 5 kN (p < 0.001; p < 0.001), but not at 6 kN (p = 0.21). Mean pull-off forces at 4 kN and 5 kN impaction forces were approximately 20% larger for 28 mm heads compared with 36 mm heads. Finite element and analytical models demonstrate that the differences in pull-off strength can be explained by differences in structural rigidity and the resulting interface pressures.ConclusionThis is the first study to show that 36 mm Co-Cr heads have up to 20% lower pull-off connection strength compared with 28 mm heads for equivalent assembly forces. This effect is likely to play a role in the high failure rates of large diameter MoM hips.Cite this article: A. R. MacLeod, N. P. T. Sullivan, M. R. Whitehouse, H. S. Gill. Large-diameter total hip arthroplasty modular heads require greater assembly forces for initial stability. Bone Joint Res 2016;5:338–346. DOI: 10.1302/2046-3758.58.BJR-2016-0044.R1.

СОВЕРШЕНСТВОВАНИЕ ТЕХНОЛОГИИ СБОРКИ СОЕДИНЕНИЯ ДЕТАЛЕЙ С НАТЯГОМ

The purpose of the study is to increase the strength of the collected compounds and to expand the technological accuracy of the method of Assembly with an interference fit. Fixed press-fit connection with interference are widely used in machine building, when the transfer of substantial axial forces are required, torques or combined loads from their joint action. Resistance to mutual misalignment of the parts in these compounds is created and supported by the forces of elastic deformation on the mating surface of the covered part (shaft) and stretching on the mating surfaces of the covering parts (holes) is proportional to the magnitude of the preload in the connection. In such compounds, the diameter of the shaft before Assembly is always larger than the diameter of the hole. In the article the analysis of the known different ways of joining parts with interference fit, including hydraulic presses. The second problem is solved due to the fact that the connection details with tightness is carried out by pressing the press stroke from one detail to another, and the breakdown of the compounds obtained by the relative longitudinal movement of parts, in which the breakdown is carried out periodically in the process of pushing through the transfer of force from the press stroke to pressed items to the elastic connection. The force on the press stroke is created by a hydraulic cylinder with large displacement, a resilient connection between the slider and pressed item performs in the cylinder, the fluid pressure and volume which can be adjusted by changing the stiffness and capacity of the drive RAM, as well as the magnitude of its longitudinal movement during the disruption. The scheme of Assembly of the connection de-hoist with tension. Original technical solution for press fit connection parts extends the technological possibilities of the equipment, increases the strength of the collected compounds and can be used in machine building, particularly in mechanical Assembly processes and, in particular, in the repair and production of agricultural machinery.

Технологическое обеспечение эксплуатационных свойств деталей машин на стадии подготовки производства

The relation of quality parameters in a surface layer of the surface worked with technological conditions of processing is stated, and also a computation definition of machinery performance attributes: fatigue resistance, durability, strength of press-fit connections are shown.

Исследование влияния режимов сегментной электромеханической закалки на сдвигоустойчивость прессового соединения типа «втулка-корпус»

Исследование влияния режимов сегментной электромеханической закалки на сдвигоустойчивость прессового соединения типа «втулка-корпус»

Failure analysis of the conical press-fit connections in a locomotive drive system

The nose-suspension drive designs with overhanging pinion are commonly applied in freight electrical locomotives because of simple, space-saving and cost-effective. The failures of conical press-fit connections in a nose-suspension drive system are analyzed in this paper. It was showed by the analysis that the crack on the inner conical surface of motor shaft is initiated by the combination of fretting and corrosion. Sharp oil groove edge and emergency of crack at the mouth of radial oil hole in pinion will accelerate the formation of fretting wear groove, and consequently the initiation of cracks. Coexist of tensile normal stress under the contact surface within the fretting zone will benefit the propagation of the fretting fatigue cracks.

Numerical Simulation and Test Research on Knurl Interference Connection

In this paper, the knurl press fit connection for motor shaft have been researched through numerical simulation and test method. A shaft with knurl press fit have been built in 3 dimensional and a finite element model then been built based it. The press in process been researched deeply and a verification test have been made to compare. After compare the calculated result and test result, the difference between simulated result and test result was small, then the relationship between interference value of press fit and max transferred torque moment was researched. The method used in this paper can be a way to research knurl press fit.

Press-Fit Connector for Automobile Electronic Control Units

A press-fit connection is a solderless electrical connection technology, which utilizes the mechanical contact force generated between through-holes on a printed circuit board (PCB) and terminals with a width slightly larger than the through-hole diameter. This technology has been widely noted recently as a measure against the Lead Free Requirement of materials comprising electric/electronic devices, especially in the area of automobile connector. For the application of this technology to automobile connectors, we have to take into account the severe requirement, such as (1) the adaptation to wider through-hole diameter tolerance range and (2) the establishment of connection reliability for the various PCB surface treatments. As a result, we have determined the minimum and maximum contact forces satisfying the long term connection reliability and designed the terminal shape, which has been refined the N-shape cross section developed before, by using three dimensional finite element methods (FEM). Furthermore, we have developed a new type of hard tin plating on terminals, thus preventing the scraping-off of tin during the insertion process, that could result in a short-circuit on the PCB, for the Organic Solderability Preservative (OSP) treated PCB. The press-fit connector for the automobile airbag Electronic Control Units (ECUs) we developed has been able to transfer to the mass-production phase successfully from August 2005.

THE NATURE AND THE AMOUNT OF WEAR OF PRESS-FIT CONNECTION OF AXLE UNIT CARS

The article deals with results of statistical research of the wear quantity of inside surface of races and wheelset neck of the car. The parametrical reliability of the stationary joint has been defined with account of oval and conelike shape of the details.