Clamping Device Research Articles

Optimization and mechanical accuracy reliability of a new type of forging manipulator

Researches on forging manipulator have enormous influence on the development of the forging industry and national economy. Clamp device and lifting mechanism are the core parts of forging manipulator, and have been studied for longer time. However, the optimization and mechanical accuracy reliability of them are less analyzed. Based on General Function(G F) set and parallel mechanism theory, proper configuration of 10t forging manipulator is selected firstly. A new type of forging manipulator driven by cylinders is proposed. After solved mechanical analysis of manipulator’s core mechanisms, expressions of force of cylinders are carried out. In order to achieve smaller force afforded by cylinders and better mechanical characteristics, some particular sizes of core mechanisms are optimized intuitively through the combined use of the genetic algorithms(GA) and GUI interface in MATLAB. Comparing with the original mechanisms, optimized clamp saves at least 8 percent efforts and optimized lifting mechanism 20 percent under maximum working condition. Finally, considering the existed manufacture error of components, mechanical accuracy reliability of optimized clamp, lifting mechanism and whole manipulator are demonstrated respectively based on fuzzy reliability theory. Obtained results show that the accuracy reliability of optimized clamp is bigger than 0.991 and that of optimized lifting mechanism is 0.995. To the whole manipulator under maximum working condition, that value exceeds 0.986 4, which means that optimized manipulator has high motion accuracy and is reliable. A new intuitive method is created to optimize forging manipulator sizes efficiently and more practical theory is utilized to analyze mechanical accuracy reliability of forging manipulator precisely.

Tne stiffness of first-order and second-order modules assembled with extracortical clamp devices

The extracortical clamp device (ECD) is a tool used in external fixation which unlike the K-wires and half-pins don’t perforate cortical bone. The use of ECD is prospective for the treatment of periprosthetic femoral fractures and in the lengthening over nail and bone transport over nail. The data on the bench tests of the osteosynthesis rigidity by the external fixation first-order and second-order modules on the base of extracortical clamp devices are observed in the article. Materials and methods. The authors made 240 bench tests using torsional-vibration machine, Indicators measuring linear displacements with a scale of 0.01 mm, bone simulators («Sawbones»), calibrated load, Ilizarov’s apparatus и extracortical fixators. The statistical analysis was performed with use software «STATISTICA» (ver. 6.0). The data obtained are presented in graphs «Box and Whisker Plot». Results. Among the investigated variants of first-order modules the better results of osteosynthesis rigidity were found in the module based on two ECD inserted at angle 60 degrees to each other and at distance of 10 cm from each other. Among the investigated second-order modules, better results of osteosynthesis rigidity were found in the module based on two ECD inserted at an angle 60 degrees to each other at distance of 10 cm from each other. Conclusion. Thus the tested modules can be used in practice in assemblies of external fixation devices in periprosthetic fractures, lengthening and bone transport over the nail.

Исследование жесткости модулей первого и второго порядка, скомпонованных с использованием экстракортикальных фиксаторов

The extracortical clamp device (ECD) is a tool used in external fixation which unlike the K-wires and half-pins don’t perforate cortical bone. The use of ECD is prospective for the treatment of periprosthetic femoral fractures and in the lengthening over nail and bone transport over nail. The data on the bench tests of the osteosynthesis rigidity by the external fixation first-order and second-order modules on the base of extracortical clamp devices are observed in the article. Materials and methods. The authors made 240 bench tests using torsional-vibration machine, Indicators measuring linear displacements with a scale of 0.01 mm, bone simulators («Sawbones»), calibrated load, Ilizarov’s apparatus и extracortical fixators. The statistical analysis was performed with use software «STATISTICA» (ver. 6.0). The data obtained are presented in graphs «Box and Whisker Plot». Results. Among the investigated variants of first-order modules the better results of osteosynthesis rigidity were found in the module based on two ECD inserted at angle 60 degrees to each other and at distance of 10 cm from each other. Among the investigated second-order modules, better results of osteosynthesis rigidity were found in the module based on two ECD inserted at an angle 60 degrees to each other at distance of 10 cm from each other. Conclusion. Thus the tested modules can be used in practice in assemblies of external fixation devices in periprosthetic fractures, lengthening and bone transport over the nail.

The Multi-Station Clamp Device of the Long Truss Girder End Parts Processing

The Long girder end parts are one of the types structure in aerospace equipment, the complex structure parts, machining parts. Usually the parts be processed on the NC milling machine, through the analysis of processing craft, design a kind of quick change type, Multi-station clamp device, instead of processing the parts on the multi-axis nc machine tool; at the same time of guarantee machining accuracy, in order to improve the production efficiency and reduce the cost of production.

Thoracoscopic left upper lobectomy with systematic lymph nodes dissection under left pulmonary artery clamping.

Video-assisted thoracoscopic surgery (VATS) has become a routine procedure for stage I and II lung cancers. However, in the presence of multiple metastasized lymph nodes invading the pulmonary artery or its major branches, the pulmonary artery have to be resected partially or sleeve resected, which could be extremely risky under thoracoscopic conditions. In order to reduce the risk of bleeding, an experienced thoracic surgeon would occlude the inflow and outflow of the pulmonary artery before anatomically dissecting the area of the pulmonary artery with tumor invasion. Different centers may use different clamping techniques and devices. Here, we report our technique of totally thoracoscopic left upper lobectomy with systematic lymph nodes dissection under pulmonary artery clamping for a 49-year-old woman with left upper lobe carcinoma. The video demonstrates our thinking and surgical process.

The Design and Experiment of Levelness-Adjustable Clamping Device for Cable Gland

This paper introduces a design of testing machine that could apply to the clamping tensile test for explosion-proof cable gland and a clamping tensile test for explosion-proof cable that based on this machine. The tension conduction system composed by wire rope and pulley supplies the test device for cable gland with tension by using standard weights counterweight. In order to ensure test precision, the testing machine loading platform can translate along the horizontal orthogonal direction X, Y and rotate around the X axis to adjust the sample space coordinates. The stress-strain sensor can measure the tension value, and the amount of displacement of the specimen can be measured by dial indicator. This paper focuses on the levelness-adjustable system and test methods.

Research on the Voltage Balance Strategy of Modular Multilevel Converter

The modular multilevel converter (MMC) does not need clamping devices and multiple independent DC voltage source and has a modular structure which is easy to be extended to any level, share a DC side, easy to direct back to back four-quadrant operation and attracts widespread attention. Due to the use of sub-module MMC suspended on the DC side capacitor voltage divider provides synthetic AC output voltage required voltage level and therefore it is essential to the stable operation of the sub-module capacitor voltage balance of the MMC. In this paper, the factors affecting the MMC sub-module capacitor voltage balancing has been carried out a detailed analysis and this paper focuses on the nominal frequency erupted module capacitor voltage control strategies and the average low frequency sub-module capacitor voltage ripple suppression strategies.

Penetration impact testing of self-reinforced composites

Penetration impact resistance is one of the key advantages of self-reinforced composites. This is typically measured using the same setup as for brittle fibre composites. However, issues with the test configuration for falling weight impact tests are reported. Similar issues have been found in literature for other composites incorporating ductile fibres. If the dimensions of the test samples are too small relative to the clamping device, then the test samples can heavily deform by wrinkling and necking. These unwanted mechanisms should be avoided as they absorb additional energy compared to properly tested samples. Furthermore, these mechanisms are found to occur more easily at lower compaction temperatures due to the lower interlayer bonding. In conclusions, the sample dimensions of ductile fibre composites should be carefully selected for penetration impact testing. If wrinkling or necking is observed, then the sample dimensions need to be increased.

The Tightening Accuracy of Workpieces in the Multiple Clamping Devices

Fixtures are used for orientation-positioning-tightening of workpieces during machining on machine tools. Multiple clamping fixtures are intended to clamp several workpieces for simultaneous or successive machining. Multiple clamping is characterized by a series of economical advantages, due to the reduction of total machining time. These advantages are more important once the number of workpieces is higher or if the machining is made with compound tools. Due to the complexity, overall size and the high number of components, the multiple clamping fixtures have diminished accuracy than simple fixture due to elastic and contact deformations of fixtures housing, of supports etc. Also, multiple clamping fixtures present diminished rigidity and dynamic stability. From the analysis of the specialized literature results that there are a few paper on the subject of multiple clamping. In the paper there are presented the causes that can lead to the diminish of the accuracy of multiple fixture. The modalities for the determination of fixtures precision are presented, also, for the parallel and serial multiple clamping fixtures.

Wide-Range Soft-Switching PWM Three-Level Combined DC–DC Converter Without Added Primary Clamping Devices

This paper proposes a novel wide-range soft-switching pulse-width modulation three-level (TL) combined dc-dc converter characterized with no added primary clamping devices and reduced output inductance value. It is well suited for high input voltage dc-dc industrial applications due to following desirable features: all the switches sustain half of the input voltage; off state voltage of the switches is directly clamped by the bulky input capacitors, and no added primary clamping devices such as clamping diodes, flying capacitors, are required; TL waveform before output filter can be achieved, which significantly reduces the value of the output inductance; the modified phase-shift control method can be utilized to achieve wide output range. The converter can obtain zero-voltage switching (ZVS) for all power switches in wide load range; furthermore, less conduction loss is added to achieve ZVS. The operation and theoretical analysis of the proposed converter are presented. Experiments are carried out to validate the proposed converter, and efficiency curves are tested and given.

Posture Alignment and Finishing System for Aircraft Wing

A novel posture alignment system based on 3-DOF locators is presented to meet the finishing need of big part such as wing after assembly. The system includes three locators for posture alignment and auxiliary clamping devices for auxiliary clamping. The structure and basic principle of device and the posture alignment principle are introduced in details. The application show the system could meet the posture alignment and finishing need of big part such as wing and provide a reference for aircraft assembly and fabrication.

A Newly Developed Clamping Device for the Tension/Compression Test at Various Strain Rates

The tension/compression hardening behavior is important in sheet metal forming processes because of complicated loading paths. Experimental methods to measure the tension/ compression behavior have not considered the effect of the strain rate although the strain rate is related to the hardening behavior of sheet metal. The tension/compression tests need to be conducted considering the strain rate to acquire accurate hardening behavior.This paper deals with an experimental technique to measure the tension/compression behavior of sheet metal at various strain rates. A new clamping device was developed to prevent a sheet specimen from buckling under compression loading condition. Compared to previous clamping devices, the clamping device was devised to uniformly impose a clamping force and easily measure the strain from side of a specimen. Tension/compression tests have been conducted at various strain rates for SPCC and DP590 with displacement of 10%. Hardening curves under the tension or compression loading condition were obtained and analyzed with respect to the strain rate.

Bauschinger Effect Exhibited in Advanced High Strength Steel Sheets under Cyclic Tension and Compression Tests

The Bauschinger effect exhibited in the advanced high strength steel sheets was examined by conducting cyclic tension-compression tests. The experimental device for performing the cyclic tension and compression tests with a single sheet specimen was developed in the present study. The experimental apparatus consists of a novel constraint jig that could prevent the sheet specimen from buckling during the compression test. The efficiency of the developed clamping device was validated by both the finite element analysis and the cyclic tension and compression tests conducted in the present study. The test results reveal that the advanced high strength steel exhibits significant Bauschinger effect. It is also confirmed that the finite element prediction of springback present in the stamping of advanced high strength steel sheets is more consistent with the experimental results if the Bauschinger effect is considered.

Improving geometrical accuracy for flanging by incremental sheet metal forming

Incremental Sheet Forming (ISF) is a manufacturing technology for individualized and small batch production. Among the opportunities this technology provides there is the possibility of a short ramp-up time and to cover the whole production chain of sheet metal parts by using a single reconfigurable machine set-up. Since recent developments proved that manufacturing of industrial parts is feasible, finishing operations such as flanging and trimming gain importance, which are an integral part of manufacturing process chains of many sheet metal parts. This paper analyses the technological capabilities of performing flanging operations by ISF. Due to the localized forming zone and the absence of surrounding clamping devices, ISF exhibits a different material flow than conventional flanging processes. In this paper, the influence of the tool path characteristics, the flange length as well as the flange radius is analysed in order to establish a process window and to compare it to the process limits of conventional flanging operations. Since geometrical deviations occur when flanging operations are performed by ISF, a new adaptive blank holder is developed, which acts in the vicinity of the forming tool and reduces unwanted deformation outside the primary forming zone. The experimental results show the benefits of the adaptive blank holder with respect to geometric accuracy. The established process window and the adaptive blank holder hence contribute to the applicability of incremental flanging operations, such that ISF can be used for all forming and flanging operations along the process chain.

Laser beam oscillation for fillet welding

In today’s automotive frame-and-body construction, laser welds are typically carried out as square butt welds in lap joints. These welds are increasingly produced by remote laser welding optics with working distances of 500 mm and more. This enables simple path programming because clamping devices are traversed over and therefore low cycle times with improved productivity is achieved. However, workpiece tolerances lead to part displacements and varying joint positions over time. These displacements have to be acted against by appropriate flange length that contain for positioning deviations. Using this concept, aspired light-weight optimisations, e.g. reducing flange length, are difficult to achieve. By using seam tracking sensors, part tolerances are automatically detected and counteracted for. In addition, joint edge detection allows constructive changes on the type of weld. Fillet welds reduce flange lengths’, improve force flow and open up possibilities for visual quality monitoring. Apart from that, vertical displacements in the form of height tolerances still occur. This needs consideration by adapting the set of welding parameter to the current welding situation. In this respect, one main welding parameter is the lateral beam offset to the upper sheet. Since body-in-white welding applications mainly comprise of zinc-coated steel sheets, special requirements for the welding process are given. Especially zero-gap-welding and welding of joints with gaps larger than 0.2 mm are critical. Using a laser beam oscillation process can stabilise these situations. Approaches to finding parameter sets are presented in this paper.

Automated Patch Clamp Analysis of nAChα7 and Na(V)1.7 Channels.

Automated patch clamp devices are now commonly used for studying ion channels. A useful modification of this approach is the replacement of the glass pipet with a thin planar glass layer with a small hole in the middle. Planar patch clamp devices, such as the three described in this unit, are overtaking glass pipets in popularity because they increase throughput, are easier to use, provide for the acquisition of high-quality and information-rich data, and allow for rapid perfusion and temperature control. Covered in this unit are two challenging targets in drug discovery: voltage-gated sodium subtype 1.7 (Na(V)1.7) and nicotinic acetylcholine α7 receptors (nAChα7R). Provided herein are protocols for recording activation and inactivation kinetics of Na(V)1.7, and activation and allosteric modulation of nAChα7R.

Square Foot Manufacturing—A Modular and Mutable Desktop Machine Tool System

This article presents the theoretical concept and the practical implementation of Square Foot Manufacturing (SFM). The concept meets the demands for micro manufacturing with modular, mutable, ad-hoc configurable, and function-integrated small machine tools. Here, a feed unit, a measuring system, a workpiece clamping device, and mechanical interfaces are described as components of the machine tool system to prove the feasibility and advantages of the SFM concept. The feed unit uses the principles of a monolithic flexure-based mechanism combined with piezo stack actuators. High precision is guaranteed by avoiding positioning errors and friction of conventional guidance systems. A low-force clamping device uses an elastic deflection of its chuck to securely fasten micro workpieces. It also acts as a workpiece carrier allowing for various production layouts. The mechanical interfaces are based on a kinematic coupling to provide high repeat position accuracy. The interface is necessary to obtain the SFM-typical high modularity and interchangeability of modules. Experimental measurements are shown to verify the performance of the components.

Possible materials and production technologies for a Special Purpose Helical Torsion Spring

There are a huge number of ideas at the area of traction drives and also at that of the epicyclic or by other words, planetary drives. The majority of these designs, contain solely rigid wheels, and the contact forces that are proportional to the transmitted torque are produced by separate clamping devices. The author introduced an innovative design, which integrates some elements with merging functions. A part of the contacting rollers are elastic ones and their shape assures the requirement of uniform strength. The curiosities of the elastic rollers are their shapes. Observing both their shapes and loads, they are helical torsion springs. They can be made of pure metals and composites, so of spring steel and also from fiber-reinforced plastics. There is a wide range of production technology considered depending on individual or mass production. The author has received some ideas from the areas of helical spring bearings, the machined torsion springs and the fiber-reinforced tubes. He also find a method to coil helical torsion spring of uniform strength from sheet metal, making the pre-manufactured “wire” of changing width by laser cutting, and to cut tubes by spark cutting.

Effect of nanosilica on the axial tensile strength of SFRC at high temperature

An independently designed heat-resistant clamping device was used in an axial tension experiment at high temperature to test three materials: normal concrete (NC), steel fibre reinforced concrete (SFRC) and SFRC with nanosilica (NSFC). The materials were heated to different temperatures in a high-temperature electric resistance furnace. The results showed that, up to 400°C, the axial tensile strength of NSFC, SFRC and NC improved as the temperature increased, reaching a maximum value at 400°C. Thereafter, a rapid drop in axial tensile strength was observed as temperature was increased further. Within the test temperature range, the tensile stress–strain curve of NSFC demonstrated a similar tendency as that for the SFRC, but NSFC generally withstood higher loads than SFRC. At room temperature, the axial tensile strength of NSFC was the highest at 2·66 MPa, which was 4·29 times that of NC and 52·9% higher than that of SFRC. The peak stress of NFSC was approximately 1·8 times that of SFRC. At 400°C, the axial tensile strength of NSFC was 3·09 MPa, 9·2% higher than that of SFRC and 119·7% higher than that of NC. At the test temperature, the fracture energy of NSFC was the highest, followed by SFRC, with NC showing the minimum fracture energy.

Investigations about the influence of the time–temperature curve on the formation of intermetallic phases during electron beam welding of steel–aluminium material combinations

Electron beam welding of square butt joints has been used for the joining of the low-alloy steel DC05 and the aluminium alloy AlMg3 without filler materials. To this end, a clamping device which allows free expansion and shrinking of the plates and also in situ heating by the electron beam has been developed. In order to examine the influence which the time–temperature curve at the edge exerts on the formation of the intermetallic phases, in a test series, the preheating temperature of the steel plate has been successively increased from 100 to 500 °C. It has been possible to identify two intermetallic phases by EBSD analysis—on the steel side, the η-phase (Al5Fe2) and, on the aluminium side, the Θ-phase (Fe4Al13). Through the correlation of the measured individual phase widths, the evaluation of the temperature curves and the results from the quasi-static tensile tests, the factors which exert influence on the development of various intermetallic phases have been identified. A maximum tensile strength of 200 MPa with a total phase width of 2.3 μm has been achieved.