Clamping Device Research Articles

Design and analysis of gripper for automatic drilling machine

In order to improve the synchronicity of the gripper of automatic drilling rig, three kinds of clamping devices for automatic drilling rig were designed to overcome the problem of deviation between the clamping center of the clamping device and the rotary center of the power head. At the same time, the driving characteristics, structures and working principle of the three grippers were introduced. With the finite element analysis conducted on the main structure parts, the results showed that the structure design and the parameter selection of the synchronous clamping mechanism component could meet the application requirements and could provide the guarantee to the reliability of the clamping mechanism and the integral performances of the automatic drilling rig.

Machine Vision Based Study on State Recognition of Milling Cutter

As a major cutting tool in machining, the wear state of a milling cutter has a directly impact on machining quality and production efficiency. In order to detect the wear conditions of milling cutter, an inspection platform based on machine vision principle is designed. Hardware arrangement of the platform is introduced and the related equipment is analysed and selected accordingly. The milling cutter clamping device used in the platform is also designed. The collection of the measured milling cutter end image is realized successfully. The image processing methods of worn cutter are studied in detail. Adaptive greyscale adjustment and median filtering are used to decrease the noise in the image. Automatic threshold segmentation and edge extraction based on Sobel operator are also designed to achieve image pre-processing. A series of image processing experiments are carried out. The feature extraction algorithm for worn milling cutter end image is presented. Through comparative experiment, the presented machine vision measurement method is efficient.

Tent-Plate AlN PMUT With a Piston-Like Shape Under Liquid Operation

In this work, a waterproof tent-plate piezoelectric micromachined ultrasonic transducer (PMUT) with enhanced performance as actuator and sensor in comparison with standard clamped PMUT is presented. The squared AlN PMUT has four linear holes that are sealed by the passive layer allowing to increase the movement and giving the capability to work in liquid environment. The dimension of the holes was optimized to increase the PMUT displacement at least twice in relation with the regular clamped device. The acoustic performance of the PMUT was simulated in COMSOL Multiphysics and the results were experimentally verified under liquid operation. The experimental transmitting sensitivity, 3.9 kPa/V, as well as the sensor sensitivity, 13.4 V/MPa, provide a 2x factor improvement in contrast with the clamped PMUT with competitive values. Additionally, the presented tent-plate PMUT provides advantages in relation with the area, cost, power consumption and imaging quality thanks to the capability to be monolithically integrated over CMOS substrates.

Application of nonlinear impedance spectroscopy for the diagnosis of lithium-ion battery cells under various operating conditions

Nonlinear impedance spectroscopy is a novel method for the diagnosis of lithium-ion battery cells. To thoroughly evaluate the application of nonlinear impedance measurements within this contribution, the topic is theoretically investigated at first. The ordinary frequency response function is extended to the Volterra model to incorporate nonlinear behavior. The applied data-driven approach simplifies the assessment of nonlinear distortions based on Fourier transforms. To experimentally analyze the frequency response of battery cells in a defined manner, a measurement setup is constructed that features a mechanical clamping device. Next to controlling the temperature and the state of charge (SoC), the force compressing the cell can be specifically adjusted with this test rig. Thereby, the influence of compressive force on the impedance spectrum and its harmonic content is examined. In addition, it is analyzed if and how the mechanical influence can be distinguished with nonlinear impedance spectroscopy from other impedance-changing conditions such as temperature and SoC. The investigation based on pouch battery cells results in diverse diagnostic scenarios, where nonlinear impedance measurements are a valuable extension to traditional battery characterization tools. The comparison is complemented by evaluating drawbacks of the method and the impact of the measurement procedure on the device under test.

An instrument for measuring blood pressure and assessing cardiovascular health from the fingertip

Despite blood pressure being one the leading modifiable risk factors for cardiovascular disease and death, it is severely under-monitored. For this challenge we propose a finger artery non-invasive tono-oscillometric monitor (FANTOM) which is an automated low-cost instrument for measuring blood pressure and hemodynamic parameters from the fingertip. The sensing technology is highly scalable and could be integrated to a pulse oximeter probe for increased patient comfort. A tonometric cuff-less mechatronic system is used to apply pressure on the fingertip for (i) measuring oscillometric blood pressure, (ii) recording arterial waveform and for (iii) constructing central blood pressure (CBP) waveform. Clinical study on volunteers (n = 33) was performed against a commercially available arm cuff device yielding systolic and diastolic readings ((mean±SD) mmHg) of (−0.9 ± 7.3) mmHg and (−3.3 ± 6.6) mmHg respectively. The results comply with the Association for the Advancement of Medical Instrumentation (AAMI) standard for non-invasive blood pressure monitors. The arterial pulse recording morphology was compared against a volume clamp device (CNSystems CNAP 500) (n = 3) resulting in similar performance. Comparison of CBP against a pulse wave analysis (PWA) device (Atcor Medical Sphygmocor XCEL) (n = 5) revealed central aortic systolic pulse (CASP) and central augmentation index (cAIx) estimates with precision and accuracy of (2.0 ± 3.7) mmHg and (1.4 ± 6.2)% respectively. In conclusion, the results indicate that the proposed technology could be useful in the development of new portable or wearable blood pressure monitors. The sensing technology is highly scalable and could be integrated to a pulse oximeter probe for increased patient comfort.

Effects of novel non-thermal atmospheric plasma treatment of titanium on physical and biological improvements and in vivo osseointegration in rats

Titanium (Ti) has achieved extensive applications due to its excellent biocompatibility and mechanical properties. Plasma can enhance surface hydrophilia of Ti with decreased carbon contamination. The traditional conditions using a single gas plasma was for longer treatment time and more prone to being contaminated. We designed and developed novel and universal apparatus and methods with a special clamping device of non-thermal atmospheric plasma (NTAP) treatment using mixed gas for Ti surface activation. We systematically and quantitatively investigated the effective effects of NTAP-Ti. The surface water contact angle decreased by 100%, the carbon content decreased by 80% and oxygen content increased by 50% in the novel NTAP-Ti surfaces. NTAP treatment accelerated the attachment, spread, proliferation, osteogenic differentiation and mineralization of MC3T3-E1 mouse preosteoblasts in vitro. The percentage of bone-to-implant contact increased by 25–40%, and the osteoclasts and bone resorption were suppressed by 50% in NTAP-Ti in vivo. In conclusion, NTAP-Ti substantially enhanced the physical and biological effects and integration with bone. The novel and universal apparatus and methods with a special clamping device using gas mixtures are promising for implant activation by swiftly and effectively changing the Ti surface to a hydrophilic one to enhance dental and orthopedic applications.

Improvement of Palletizing Robot’s Clamp Device for Cigarette Products

In order to reduce the drop number of cigarette packing cases and downtime during the robot palletizing, and improve palletizing efficiency, the key technology of the robot’s clamp device was improved. The improvement techniques included vacuum suction cups specification optimizing, suction cups horizontal and vertical balancing layout, robot running smoothly, increasing the intake pipe, multi-loop vacuum generator. These techniques were applied to KUKA KR150L 150/3 robot, tested on normal and circular cigarette packing cases such as Yuxi (Hard Harmony)brand produced by Yuxi cigarette factory. The results showed that the improvement of robot palletizing cigarette packing cases is stable, and the average drop number is reduced to 13/month from 123/month before improvement, the number of downtime is reduced to 14 times/month from 125 times/month, the equipment efficiency is improved to 9.6/min. The improvement can provide technical support for the stable operation of the robot palletizing cigarette cases.

Role of residual ferrites on crevice SCC of austenitic stainless steels in PWR water with high-dissolved oxygen

The crevice stress corrosion cracking (SCC) susceptibility of austenitic stainless steels was evaluated in simulated pressurized water reactor (PWR) environments. To simulate the abnormal condition in temporary clamping devices on leaking small bore pipes, crevice bent beam (CBB) tests were performed in the oxygenated as well as hydrogenated conditions. No SCC cracks were found for SS316 in both conditions. SS304 also showed good resistance in the hydrogenated condition. However, all SS304 specimens showed SCC cracks in the oxygenated condition, indicating poor crevice SCC resistance. It was found that residual ferrites were selectively dissolved because of the galvanic corrosion coupled with the neighbouring austenite phase, resulting in SCC initiation in SS304. Crack morphologies were mostly transgranular assisted by the damaged δ-ferrite and deformation-induced slip bands.

DESIGN AND DEVELOPMENT OF PORTABLE VACUUM CLAMPING (PVAC CLAMP) FOR TOOL ROOM

Clamping in tool room usually uses tools and holding devices such as vise to clamp workpieces. However, conventional clamping device such as vise is time consuming, expensive and can not hold thin workpiece. Therefore, this project presents the design and development of portable vacuum clamping (Pvac CLAMP) for tool room to overcome those limitations. To design and develop Pvac CLAMP, the machines used in the process are milling machine and drilling machine. After Pvac CLAMP had been developed, a test were carried on the Pvac CLAMP. The test was surface roughness measurement. The result shows that Pvac CLAMP has better surface roughness than theconventional vise about 40% reduction.

Distortion and Dilution Behavior for Laser Metal Deposition onto Thin Sheet Metals

The combination of additive manufacturing and incremental sheet forming offers great flexibility in the manufacture of function-integrated parts. In this study, both processes were carried out by the same CNC machine. This offers the possibility to manufacture large-scale lightweight parts with smaller additive parts on it in one machine and clamping device. Additionally, the process combination can lead to a reduced energy and material consumption for small batch sizes. DC01 sheets are used as a substrate with two different initial conditions. The first condition is as delivered steel sheet and the second is an incrementally formed with a thickness of 0.5 mm. The additive manufacturing was conducted by laser metal deposition (LMD). The powder material is a stainless steel 316 L. A segmentation of the cladding surface was applied and the path strategy of the laser movement was varied simultaneously to analyse the warpage of the thin substrate. It is shown that there is a dependency between the build-up strategies and the melt pool temperature, the thermal distortion, the dilution and the size of the cladding area. A segmentation of the working surface causes a lower melt pool temperature and thermal distortion. The lower melt pool temperature also generates a reduced dilution zone.

Comparative Evaluation of Wide-Range Soft-Switching PWM Full-Bridge Modular Multilevel DC–DC Converters

This paper discusses some wide-range soft-switching full-bridge (FB) modular multilevel dc–dc converters (MMDCs), and a comparative evaluation of these FB MMDCs is also presented. The discussed topologies have all merits belonging to conventional FB MMDCs, e.g., smaller voltage stress on the primary switches, no added primary clamping devices and modular primary structure. In addition, the primary switches in each converter can obtain zero-voltage switching (ZVS) or zero-current switching (ZCS) in a wide load range. Two presented topologies are selected as examples to discuss in detail. The proposed FB MMDCs are assessed and evaluated based on performance, components and topology structure indices, such as soft switching characteristics, current stress, power loss distribution, number of added devices, complexity of structure and added cost. Experimental results are also included to verify the feasibility and advantages of the new topologies.

CLAMPING DEVICES WITH SPLIT SLEEVES. ACCURACY OF BLANKS INSTALLATION AND MACHINING

A special place in the known technological system “MDTP” (machine, device, tool, part) is taken by clamping devices since they are intended for positioning of the blank (part) subject to machining in space to prevent its displacement under the action of cutting forces. The devices significantly influence the accuracy of the clamped blank machining. The ratio of inaccuracies caused by the devices may prevail in the total balance of inaccuracies. This may take place during machining of such types of blanks as rings, bushings and cups, especially those with thin walls. The mentioned blanks have a great number of structural configurations, they vary in installation bases, rigidity, accuracy requirements and batch quantity, etc. All this has led to a great number of devices used to install such blanks as rings, bushings and cups. These devices were selected as objects of study. The review thereof has shown two contradictory tendencies: increase in accuracy of machining of blanks clamped in the devices; expansion o the devices’ processing possibilities, in the first instance expansion of the diameter range of blanks which can be installed in a single device. On the basis of the study performed it was determined that mandrels with split sleeves are most promising since they are highly accurate and have a wide range, but there is some room for improvement of these characteristics. The article describes accuracy of blanks’ installation and machining in mandrels with split sleeves and contains recommendations on rational use of such mandrels.

End-forming of Continuous Fibre-reinforced Thermoplastic Tubes

Continuous fibre-reinforced thermoplastic tubes (CFRTT) are suitable for many lightweight applications including the usage as structural parts or pressure lines. For these applications, geometries at the tube ends are crucial to enable tight fit connections. In this work, we present a forming process to manufacture flanges and beadings at the ends of CFRTT by means of circumferential forming. The setup is subdivided in three functional units, namely a clamping device, an inductive heating and a shape-related forming unit. The flow of the developed process is presented as well as the tool concepts. Additionally, the fibre orientations in the outer layer of the manufactured parts are measured using an optical method and a MATLAB-tool and compared to the initial angles of the semi-finished tube. Finally, the microstructure of the parts is analyzed.

Finish machining of Ti6Al4V SLM components under consideration of thin walls and support structure removal

Using additive manufacturing (AM) technologies such as powder bed based selective laser melting, it is possible to realize new bionic designs for Ti6Al4V aerospace components, thus significantly reducing weight. With these technologies, the goals of reducing emissions in the aviation industry can be achieved while passenger numbers are growing at the same time. In order to fulfill the quality requirements of the components, the AM process chain includes many further process steps in addition to melting, such as heat treatment.Furthermore, the functional surfaces must be machined and the support structures removed. These are essential for selective laser melting. The paper shows how the deflection of the workpiece can be minimized by milling thin-walled functional surfaces using a clamping device with support points. This increases the geometric accuracy considerably.Finally, the paper shows the results for milling support structures. The design of the support structure has a high effect on the machining behavior. Finally, results are presented that show the influence of different milling strategies on the surface quality of AM components, considering the support structures.

Computer analysis of workpieces auto-heating during surfacing

The method for calculating of the temperature when surfacing of complex-shaped workpiece by solving non-stationary and nonlinear equation of thermal conductivity in heterogeneous layer, which allows taking into account the elements of the clamping device and not describing numerous boundary conditions is presented. Example for calculating of the heating temperature of spherical plug of the ball valve during surfacing on spherical surface via welding deposition with spiral and back-and-forth movement of the heat source is given. The calculated temperature variation in the base material during the surfacing of specifi c workpieces makes it possible to develop program for adjusting of the surfacing mode to ensure the stability of the dimensions and properties of the deposited layer.

Morphological studies and wear behavior of electro discharge coated steel

This paper elaborates on the deposition of tungsten and copper (W-Cu) material on the AISI 1020 steel substrate and the method used for deposition with its surface and wear characteristics. The tool electrode used is of tungsten copper (W-Cu) manufactured by powder metallurgy (PM) route with different ratios of tungsten and copper metal powders. The process carried out for deposition is by electro-discharge coating (EDC). In this, the tool electrode material is melted and deposited on the substrate by the application of heat energy due to sparking between the electrode and the substrate. Then a thick layer of W-Cu coating is formed on the substrate material. The substrate material of AISI 1020 steel was cut in cylindrical shapes of 10 mm diameter and height 10 mm by wire cut EDM machine and was then surface grinded for the accuracy and polished surface. The cylindrical size was considered for holding the specimen in the clamping device of wear testing machine easily during wear testing. The wear behavior of the coated samples is assessed by the pin on disc method. The effect of mixing ratio, micro hardness, Scanning Electron Microscope (SEM), Energy Disperse Spectroscopy (EDS) analysis, Coefficient of friction (COF) etc., for different composition coated samples has been investigated. The results show that the micro hardness achieved in the range 51-84HV for coated specimens of W-Cu of different composite substrates. The COF was achieved in the range of 0.16 to 0.31 after wear experimentation. The microstructures of the coated samples are analyzed before and after wear by using SEM and EDS.

Design of High-Voltage-Tolerant Power-Rail ESD Protection Circuit for Power Pin of Negative Voltage in Low-Voltage CMOS Processes

In the implanted biomedical devices, the silicon chips with monopolar stimulation design have been widely applied. To protect the negative-voltage pins of the implanted silicon chip from the electrostatic discharge (ESD) damage, the ESD protection circuit should be carefully designed to avoid any wrong current path under normal circuit operation with the negative voltage. In this article, a new power-rail ESD clamp circuit for the application with an operating voltage of −6 V has been proposed and verified in a 0.18- $\mu \text{m}$ 3.3-V CMOS process. The proposed circuit, realized with only 3.3-V nMOS/pMOS devices, is able to prevent the gate-oxide reliability issue under this −6-V application. With the proposed ESD detection circuit, the turn-on speed of the main ESD clamp device, which is a stacked-nMOS (STnMOS), can be greatly enhanced. The STnMOS with a width of $400~\mu \text{m}$ can sustain over 8-kV human body model (HBM) ESD stress and perform low standby leakage current of ~5.4 nA at room temperature under the circuit operating condition with −6-V supply voltage.

Automated Dynamic Clamp for Simulation of IK1 in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes in Real Time Using Patchliner Dynamite8.

Current in vitro assays typically poorly predict cardiac liability as they focus on single ion channels overexpressed in cell lines. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), on the other hand, provide a unique opportunity for drug testing on human cardiomyocytes using high-throughput systems. However, these cells can differ from adult cardiomyocytes in their ion channel expression and, therefore, electrophysiologic properties. One of the main challenges of hiPSC-CMs is the physiologic expression of ion channels such as the inward rectifiers (e.g., Kir2.1-2.3), which conduct the cardiac inward rectifier potassium current (IK1 ). IK1 is one of the primary contributors in maintaining a stable resting membrane potential in cardiac cells, which is essential for excitability. This is only expressed in low levels, or sometimes not at all, in hiPSC-CMs as shown by patch clamp studies. Dynamic clamp is a method of electronically introducing ion currents (e.g., IK1 ) into cells to compensate for the lack of endogenous expression, thus offering the potential to record more stable action potentials in hiPSC-CMs. In this article, we describe the method of using hiPSC-CMs on an automated patch clamp device (Patchliner) coupled with the automated dynamic clamp add-on (Dynamite8 ). We describe protocols for optimized cell handling and harvesting for use on the Patchliner and the steps required for automated execution of experiments and data analysis in dynamic clamp mode. © 2019 by John Wiley & Sons, Inc. Basic Protocol: Recording action potential pharmacology from human induced pluripotent stem cell-derived cardiomyocytes in automated patch clamp combined with dynamic clamp to introduce simulated IK1 and compensate seal resistance Support Protocol 1: Cardiomyocyte plating and culture Support Protocol 2: Cell harvesting and dissociation Alternate Protocol: Recording action potential pharmacology at physiologic temperatures.

Operation and Control of a Seven-Level V-Clamp Multilevel Converter

Multilevel converters are well suited for high-power and high-quality power conversion. This paper presents a new seven-level V-clamp multilevel converter (VMC) with reduced clamping devices. All phases of the VMC share common DC-link capacitors and realize bidirectional power conversion without flying capacitors. Each branch of the VMC sustains only a single-level voltage of the DC-link capacitors during its commutation process. Hence, the series switches can be controlled as simple as one switch and the dynamic voltage unbalancing issue is avoided. In this paper, the operation principle and the modulation method of the VMC are analyzed in detail. In addition, compensation control for non-ideal factors is designed to improve the output performance. The output fundamental distortion is compensated and the harmonics are reduced. Finally, a laboratory prototype of the seven-level VMC is set up to verify the feasibility of the presented topology and analysis.

Instrumented clamping device and numerical simulations to study machining distortion

Machining part distortion is due to residual stresses induced by previous manufacturing processes. This study aims to evaluate the influence of machining conditions on AISI 316L plate distortion. Therefore, a special experimental device with force sensors integrated in the clamping system and numerical model of distortion were developed. Residual stresses due to previous machining processes were measured using a layer removal method and neutron diffraction technique. Then, distributions of these residual stresses were integrated in a developed model of machining distortion, which considers the clamping and machining sequence effects after each stage of the toolpath. A comparison of the experimental and numerical results revealed that the finite element method can adequately predict machining distortion. The results also suggest that clamping and machining sequence can affect part distortion.