The Frictional Force between Slug and Die in Shear Cutting after Material Separation

2021 ◽  
Vol 883 ◽  
pp. 285-293
Author(s):  
Jens Stahl ◽  
Isabella Pätzold ◽  
Lucas van den Bosch ◽  
Alexander Kindsmüller ◽  
Roland Golle ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Frictional Force ◽  
Simulation Models ◽  
Frictional Forces ◽  
Inner Diameter ◽  
Material Separation ◽  
The Difference ◽  
Process Disturbances ◽  
Belt Feeder ◽  
Tool Damage

Frictional forces in sheet metal blanking are central in different aspects, e.g. in wear prediction, validation of simulation models or in so called slug pulling. The latter is a phenomenon where the slug is pulled out of the die by the punch after the sheet metal is separated. This leads to process disturbances reaching from a blocked belt feeder up to severe tool damage caused by the simultaneous cutting of the slug and the sheet metal strip. A sufficiently high frictional force between the slug and the die prevents this effect. Despite its importance, this force and its causes have not yet been investigated in detail. A method was developed in this paper to measure the frictional force between slug and die. A shear cutting tool with an integrated piezoelectric load cell and an inductive position sensor was used on a stamping press to cut sheet metal made of CuSn6 (R350, thickness 1 mm). The die clearance, the punch edge radii and the lubrication conditions were varied. A larger die clearance resulted in a lower frictional force while a larger punch edge radius increased it significantly. Lubrication reduced the frictional force, especially for small die clearances. Finally, the cause of the frictional force was investigated by identifying the relevant springback modes of the slugs. This was carried out by correlating the slugs' deflection, oversize, and clean cut height with the frictional force. Especially the slug oversize, i.e. the difference between the slug's diameter and the die's inner diameter, revealed a strong correlation. Calculations showed that the deformation in radial direction is the main cause of the frictional force between slug and die. It suggests that the slug oversize is a good measure for the magnitude of the frictional force.

scholarly journals Cyclic fatigue resistance of 2Shape, Twisted File and EndoSequence Xpress nickel-titanium rotary files at intracanal temperature

2018 ◽  
Vol 12 (4) ◽  
pp. 283-287 ◽  
Author(s):  
Gülşah Uslu ◽  
Taha Özyürek ◽  
Mustafa Gündoğar ◽  
Koray Yılmaz
Keyword(s):  
Fatigue Resistance ◽  
Statistical Significance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Bonferroni Correction ◽  
Significant Difference ◽  
Inner Diameter ◽  
The Difference ◽  
Number Of Cycles ◽  
Analyze Data

Background. The aim of this study was to compare the cyclic fatigue resistance of 2Shape, Twisted File (TF) and EndoSequence Xpress (ESX) nickel-titanium rotary files at intracanal temperature (35°C). Methods. Twenty 2Shape TS1 (25/.04), 20 TF (25/.04) and 20 ESX (25/.04) files were tested for cyclic fatigue at intracanal temperature (35°C). All the instruments were rotated in artificial canals which were made of stainless steel with an inner diameter of 1.5 mm, 60° angle of curvature and a radius curvature of 5 mm until fracture occurred; the time to fracture was recorded in seconds using a digital chronometer and the number of cycles to fracture (NCF) for each file was calculated. Kruskal-Wallis test with Bonferroni correction was performed to statistically analyze data using SPSS 21.0. Statistical significance was set at P<0.05. Results. NCF values revealed that the 2Shape had significantly the highest cyclic fatigue resistance, followed by TF and ESX at intracanal temperature (P<0.05). The difference was significant between the TF and ESX groups (P<0.05). There was no significant difference among the 2Shape, TF and ESX files with respect to the lengths of the fractured file fragments (P>.05). Conclusion. Within the limitations of present study, it was concluded that the cyclic fatigue resistance of 2Shape files at the intracanal temperature is higher than that of TF and ESX files.

scholarly journals Modeling of contact stress and tool-based frictional forces considering edge effect through material separation exploration

2021 ◽  
Author(s):  
Weiwei Zhang ◽  
Jian Weng ◽  
Kejia Zhuang ◽  
Cheng Hu ◽  
Xing Dai ◽  
...  
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Stress ◽  
Finite Element Simulations ◽  
Cutting Edge ◽  
Contact Model ◽  
Feature Points ◽  
Normal Contact ◽  
Frictional Forces ◽  
Material Separation

Abstract Cutting tools with round edge can enhance the performance of machining difficult-to-machine materials, while the complex contact mechanism related to micro cutting edge limits the deeper understanding of cutting mechanics. Material separation, which is associate to plough mechanism with formation of dead metal zone (DMZ), also requires the analysis of contact behavior. This study develops a contact model along the round edge together with the illustration of DMZ, with three contact feature points defined to explain the contact situation between workpiece and cutting edge. Among these feature points, two separation points related to DMZ classify the sliding and sticking region considering the dual-zone approach. The stagnation point is the zero shear stress point where a sudden change in shear stress direction happens. Besides, the parabolic stress model obtained from finite element simulations is established to define the normal contact distribution along the round edge. In this basis, the tool-based frictional forces are determined and two contact force components are classified for different contact regions. The proposed contact feature points and contact stress are validated through illustration with finite element simulations. Besides, orthogonal cutting tests ensure the practicality and accuracy of the proposed contact model and predicted cutting forces.

A Study of Frictional Forces between Orthodontic Brackets and Archwires

1994 ◽  
Vol 21 (4) ◽  
pp. 349-357 ◽  
Author(s):  
Alison Downing ◽  
John McCabe ◽  
Peter Gordon
Keyword(s):  
Stainless Steel ◽  
Frictional Force ◽  
Nickel Titanium ◽  
The Other ◽  
Friction Testing ◽  
Beta Titanium ◽  
Polycrystalline Ceramic ◽  
Ceramic Brackets ◽  
Frictional Forces ◽  
Testing Assembly

The differences in magnitude of static and kinetic frictional forces generated by 0·022 × 0·030-inch stainless steel (Dentaurum®) and polycrystalline ceramic (Transcend®) brackets in combinntion with archwires of different sizes (0·018 inch and 0·019 × 0·025 inch) and materials (stainless steel, nickel-titanium, and beta-titanium) at a constant ligature force were investigated. A friction-testing assembly using the Instron machine was used. In all cases, the static frictional force was greater than the kinetic frictional force. There were no significant differences in the frictional forces generated by stainless steel and polycrystalline ceramic brackets. Beta-titanium archwires produced greater frictinal forces than the other two materials. Increasing the archwire diameter increased the frictional force.

Abstract 16720: Cytoglobin Regulates Cardiovascular Function and Vessel Tone by Controlling the Rate of Vascular Nitric Oxide Metabolism

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Xiaoping Liu ◽  
Mohamed A El-Mahdy ◽  
Raed S Ismail ◽  
Sean Little ◽  
Le T Thuy ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Vascular Wall ◽  
No Donor ◽  
Nitric Oxide Metabolism ◽  
No Consumption ◽  
Potent Vasodilator ◽  
Inner Diameter ◽  
The Difference ◽  
Synthase Inhibitor

Cytoglobin (Cygb) can effectively metabolize nitric oxide (NO), a potent vasodilator, in the presence of oxygen and reductants. Cygb in the vascular wall may affect cardiovascular functions by changing the rate of NO metabolism. In this study, we directly tested the vascular role of Cygb using Cygb knockout (Cygb-/-) mice. The mean blood pressure of Cygb-/- and C57BL/6 wild type (WT) mice was 65.3 ± 1.9 mmHg and 93.7 ± 1.5 mmHg, respectively (n=10). Using echocardiography, we observed that cardiac output (CO) was increased in Cygb-/- mice compared to WT with values of 29.8 ± 3.9 vs 17.7 ± 0.9 ml/min. The systemic vascular resistance (SVR) of Cygb-/- mice was decreased by ~60% vs that of WT mice (Fig. 1). Further, the inner diameter (id) of aorta of Cygb-/- mice was dilated compared to WT with values of 2.2 ± 0.1 mm vs 1.5 ± 0.05 mm (n=5), respectively. After treatment with the NO synthase inhibitor L-NAME, no difference in the aortic id remained between Cygb-/- (1.55 ± 0.03 mm) and WT (1.49 ± 0.02 mm) mice, indicating that the NO pathway is responsible for the difference in vascular inner diameters and tone. Myograph experiments show that the aortic vasodilation response of Cygb-/- mice is much more sensitive to acetylcholine (Ach) or the NO donor nitroprusside (SNP) (EC50 shifts from 13 nM and 2.9 nM (WT mice) to 0.33 nM and 0.16 nM (Cygb-/-) for Ach and SNP, respectively). Using NO electrodes to measure the rate of NO consumption by SMCs and quantitative imunoblotting to estimate Cygb content in RSMCs-AR and Cygb knockdown RSMCs, we observed that 90% of NO consumption by RSMCs-AR is caused by the intracellular Cygb. Our results indicate that Cygb deficiency in the vascular wall of Cygb-/- mice greatly reduces the rate of NO metabolism and increases vascular NO concentration, resulting in vasodilation, increase in vessel lumen diameter, and decrease in SVR. These results demonstrate that Cygb regulates cardiac function and vessel tone by controlling the rate of vascular NO metabolism.

Peristaltic Flow of a Jeffery Fluid with Heat Transfer in an Inclined Porous Tube under the Influence of Slip and Variable Viscosity

2019 ◽  
Vol 393 ◽  
pp. 16-30 ◽  
Author(s):  
Gudekote Manjunatha ◽  
Hanumesh Vaidya ◽  
Choudhari Rajashekhar ◽  
K.V. Prasad
Keyword(s):  
Heat Transfer ◽  
Frictional Force ◽  
Variable Viscosity ◽  
Pressure Rise ◽  
Velocity Slip ◽  
Slip Parameter ◽  
Porous Tube ◽  
Closed Form Solutions ◽  
Long Wavelength ◽  
Frictional Forces

The present paper investigates the role of heat transfer on peristaltic transport of Jeffery liquid in a porous tube. The effect of variable viscosity and slip impacts are taken into account. The closed-form solutions are obtained with the help of long wavelength and small Reynolds number. The results of physiological parameters on velocity, pressure rise, frictional force, trapped bolus, and temperature are plotted graphically. It is seen that the pressure rise and the frictional forces decline with an expansion in the viscosity parameter. The study further demonstrates that an increase in the value of the slip parameter significantly alters the pressure rise, frictional force, and temperature. Moreover, the volume of trapped bolus increases with an increase in the value of the velocity slip parameter.

Turbine Blade Tip Clearance Measurements in a Large Industrial Two-Shaft Gas Turbine

1982 ◽  
Author(s):  
J. Van Den Andel
Keyword(s):  
Gas Turbines ◽  
Electronic Control Unit ◽  
Control Unit ◽  
Tip Clearance ◽  
Start Up ◽  
Blade Tip ◽  
Inner Diameter ◽  
The Difference ◽  
Touch Probe ◽  
Blade Tip Clearance

In horizontally split gas turbines, distortions of the cylinders may be expected, especially during start-up conditions. This article describes how the distortions of an inner cylinder were first measured outside the turbine by placing it on a horizontal boring mill while heating the inner diameter. Modifications were made to reduce the distortion and the difference is shown. The cylinder was then tested in the actual turbine (CW352) where the diameter was compared with the presumably perfect circle described by the passing blades. Three monitors were used to determine the gap between the blades and the seal plates which are a part of the inner cylinder. Described is how a high accuracy is obtained using complex touch probe actuators and an electronic control unit which computes the blade-to-seal-plate gap and displays it for read out. A computer interface allows the information to be stored in the master computer for recall.

Study on Heat Storage Change Characteristics of a Double Reheat Boiler During Load Cycling Processes

2019 ◽  
Author(s):  
Zhu Wang ◽  
Ming Liu ◽  
Yongliang Zhao ◽  
Daotong Chong ◽  
Junjie Yan
Keyword(s):  
Steady State ◽  
Real Time ◽  
Temperature Control ◽  
Power Plants ◽  
Heat Storage ◽  
Simulation Models ◽  
Working Medium ◽  
Load Cycling ◽  
Reheat Steam ◽  
The Difference

Abstract The stability of the live and reheat steam temperatures is of great significance for the efficient, flexible and safe operation of coal-fired power plants. The double reheat boilers are large inertia, non-linearity and high coupling. Therefore, the temperature controls of live and reheat steams are very difficult during load cycling processes. The heat storage in the double reheat boiler changes during load cycling process, which will affect the performances of temperature control. In this study, dynamic simulation models of an ultra-supercritical double reheat tower boiler and its temperature control models are developed based on the GSE software. These models are validated. Then, changes of the boiler system heat storage during different load cycling processes are studied. Results reveal that the metal heat storage is more than working medium ones at steady state load. However, the changing quantities of working medium heat storage are more than the metal ones between different loads. During load cycling processes, the changing tendencies of reheat steam temperatures, the difference of heat storage between real-time and steady state values (DHSBRS) and the difference of coal feeding rate between real-time and steady values (DCBRS) are similar. The fluctuations of reheat steam temperatures have a delay compared with DHSBRS ones, and the fluctuations of DHSBRS fluctuation have a delay compared with DCBRS ones. The delay time increases with the load cycling rates. The results are aimed at providing some guidance for the control system design of the double-reheat boiler system and the safe and flexible operation of power plants.

Opening plugged tympanostomy tubes: Effect of inner diameter and shaft length

2005 ◽  
Vol 132 (2) ◽  
pp. 322-326 ◽  
Author(s):  
Ajay J. Mehta ◽  
Gary R. Stevens ◽  
Patrick J. Antonelli
Keyword(s):  
Study Design ◽  
Middle Ear ◽  
Ex Vivo ◽  
Tympanostomy Tube ◽  
Ex Vivo Model ◽  
Shaft Length ◽  
Tympanostomy Tubes ◽  
Inner Diameter ◽  
The Difference

OBJECTIVE: To determine whether tympanostomy tube (TT) inner diameter or shaft length impacts the rate of mucoid plug clearance. STUDY DESIGN AND SETTING: Ex vivo model. Silicone TTs with different inner-diameters (ID) and shaft-length (SL) pairings (1.14 mm ID × 12 mm SL versus 1.14 mm ID × 1 mm SL; 1.14 mm ID × 4.8 mm SL versus 1.32 mm ID × 4.8 mm SL) were plugged with middle-ear mucus (n = 15 per group) and placed in a model ear chamber. Ofloxacin otic solution was instilled into the chamber to cover the plugged TT, and the time to clearance of each plug was recorded. RESULTS: TTs with larger IDs ( P = 0.019) and greater SLs ( P = 0.033) cleared plugs more rapidly. However, the difference in the percentage of tubes that unplugged was not significant ( P = 0.151). CONCLUSIONS: Rate of ex vivo TT plug clearance may be altered by changing TT ID and SL.

Study on the Difference of Frontal Impact Response among People of Different Sizes

2010 ◽  
Vol 34-35 ◽  
pp. 111-116 ◽  
Author(s):  
Li Bo Cao ◽  
Chong Zhen Cui ◽  
Ning Yu Zhu ◽  
Huan Chen
Keyword(s):  
Human Body ◽  
Injury Risk ◽  
Simulation Models ◽  
Restraint System ◽  
Frontal Impact ◽  
Occupant Restraint System ◽  
Impact Simulation ◽  
The Difference ◽  
Human Body Models ◽  
Multi Body

In this article, seven frontal impact simulation models with same restraint system and different human body models were established through the use of multi-body kinematics software MADYMO. The injuries in head, chest and femurs of different human models and the differences of these injuries were analyzed in detail. The weighted injury criterion was adopted to evaluate the overall injuries of different human body models. The results shows that the injury risk of smaller human body is much higher than the taller human body, and existing occupant restraint system that protects the 50th percentile American occupant well protects other size occupant poorly.

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