Influence of Adaptive Gap Control Mechanism and Tool Electrodes on Machining Titanium (Ti-6Al-4V) Alloy in EDM Process

Titanium alloy is widely used for orthodontic technology and easily machined using the EDM process. In the EDM process, the workpiece and tool electrode must be separated by a continuous air gap during the machining operation to generate discharge energy in this method. In the present study, an endeavor was made to analyze the effects of a servo feed air gap control and tool electrode in the EDM process. The developed mechanical setup consists of a linear action movement with zero backlash along the X-axis, which can be controlled up to 0.03 mm. It was observed that the suggested air gap control scheme can enhance the servo feed mechanism on a machining titanium alloy. A tungsten carbide electrode can enhance the surface measures owing to its ability to produce tiny craters with uniform distribution. Since it produces a little crater and has a higher melting point, a tungsten carbide electrode can create lesser surface roughness than a copper tool and brass tool electrode.

Component gap control during posterior-stabilised total knee arthroplasty using the posterior condylar pre-cut technique

Purpose Adjusting the gap lengths to ensure equal lengths in both extension and flexion during total knee arthroplasty (TKA) is important for achieving successful outcomes. We designed a new pre-cut trial component (PCT) for posterior-stabilised (PS) TKA and aimed to determine whether the pre-cut technique is useful for component gap (CG) control in PS TKA. Methods A total of 70 knees were included. The PS PCT for PS TKA is composed of a 9-mm-thick distal part and 5-mm-thick posterior part with a cam structure. First, the distal femur and proximal tibia were cut to create an extension gap. Next, a 4-mm pre-cut was made from the posterior femoral condylar line; then, the PS PCT was attached, and the CGs were checked and compared at 0° and 90° knee flexion. Final CGs with the trial femoral components were compared with gaps in PS PCT at 0° and 90° knee flexion. Results CGs using PS PCTs were 10.2 mm at 0° and 13.6 mm at 90° knee flexion. According to the release of the posterior capsule at intercondylar notch and the adjustment of the cutting level of posterior femoral condyle, the final CG on knee extension was 11.3 mm; it did not significantly differ from CGs with PS PCT. The final CG at 90° knee flexion was 12.7 mm; it did not significantly differ from the estimated gap (12.4 mm) in PS PCT after flexion gap control. Conclusion CG control using PS PCT is a useful technique during PS TKA. Level of evidence Level IV: Case series.

Experimental Validation and Numerical Simulation of Flexible and Micro-scale Roll Gap Control Technology

To obtain a better ability of strip flatness control, this paper proposes a new flexible and micro-scale roll gap control technology. According to the principle of roll profile electromagnetic control technology (RPECT), a new electromagnetic control rolling mill with the function of roll profile control and large diameter ratio rolling is designed and built. To analyze the flatness control ability of this mill, a comprehensive finite element model (FEM) is established and verified, which includes a FEM for predicting the electromagnetic control roll profile and a FEM of rolling process. The simulation results show that the crown control ability of RPECT is stronger than the quadratic crown control ability, and the effect of tension on the roll gap shape crown is small. The results in the indentation experiment and the rolling experiment show that increasing the roll crown of electromagnetic control roll can adjust the strip shape form edge wave to non-wave, and middle wave. The feasibility of using RPECT to adjust the roll gap shape has been verified, and the roll gap control goal of uniform transverse size distribution can be achieved.

Syntactic Typology

The major achievements in syntactic typology garnered nearly 50 years ago by acclaimed typologists such as Edward Keenan and Bernard Comrie continue to exert enormous influence in the field, deserving periodic appraisals in the light of new discoveries and insights. With an increased understanding of them in recent years, typologically controversial ergative and Philippine-type languages provide a unique opportunity to reassess the issues surrounding the delicately intertwined topics of grammatical relations and relative clauses (RCs), perhaps the two foremost topics in syntactic typology. Keenan’s property-list approach to the grammatical relation subject brings wrong results for ergative and Philippine-type languages, both of which have at their disposal two primary grammatical relations of subject and absolutive in the former and of subject and topic in the latter. Ergative languages are characterized by their deployment of arguments according to both the nominative (S=A≠P) and the ergative (S=P≠A) pattern. Phenomena such as nominal morphology and relativization are typically controlled by the absolutive relation, defined as a union of {S, P} resulting from a P-based generalization. Other phenomena such as the second person imperative deletion and a gap control in compound (coordinate) sentences involve as a pivot the subject relation, defined as an {S, A} grouping resulting from an A-based generalization. Ergative languages, thus, clearly demonstrate that grammatical relations are phenomenon/construction specific. Philippine-type languages reinforce this point by their possession of subjects, as defined above, and a pragmatico-syntactic relation of topic correlated with the referential prominence of a noun phrase (NP) argument. As in ergative languages, certain phenomena, for example, controlling of a gap in the want-type control construction, operate in terms of the subject, while others, for example, relativization, revolve around the topic. With regard to RCs, the points made above bear directly on the claim by Keenan and Comrie that subjects are universally the most relativizable of NP’s, justifying the high end of the Noun Phrase Accessibility Hierarchy. A new nominalization perspective on relative clauses reveals that grammatical relations are actually irrelevant to the relativization process per se, and that the widely embraced typology of RCs, recognizing so-called headless and internally headed RCs and others as construction types, is misguided in that RCs in fact do not exist as independent grammatical structures; they are merely epiphenomenal to the usage patterns of two types of grammatical nominalizations. The so-called subject relativization (e.g., You should marry a man who loves you) involves a head noun and a subject argument nominalization (e.g., [who [Ø loves you]]) that are joined together forming a larger NP constituent in the manner similar to the way a head noun and an adjectival modifier are brought together in a simple attributive construction (e.g., a rich man) with no regard to grammatical relations. The same argument nominalization can head an NP (e.g., You should marry who loves you). This is known as a headless RC, while it is in fact no more than an NP use of an argument nominalization, as opposed to the modification use of the same structure in the ordinary restrictive RC seen above. So-called internally headed RCs involve event nominalizations (e.g., Quechua Maria wallpa-ta wayk’u-sqa-n-ta mik”u-sayku [Maria chicken-acc cook-P.nmlzr-3sg-acc eat-prog.1pl], lit. “We are eating Maria cook a chicken,” and English I heard John sing in the kitchen) that evoke various substantive entities metonymically related to the event, such as event protagonists (as in the Quechua example), results (as in the English example), and abstract entities such as facts and propositions (e.g., I know that John sings in the kitchen).

Evaluation of Bonding Gap Control Methods for an Epoxy Adhesive Joint of Carbon Fiber Tubes and Aluminum Alloy Inserts

The aim of this paper is to compare two methods of epoxy adhesive bond gap control: one with a geometrical (mechanical) solution and the other with glass beads, which have the diameter of the desired bond gap and are mixed with an epoxy adhesive. The adhered materials were carbon fiber composite tubes and aluminum alloy inserts, which were used as wishbones in a suspension system of a motorsport vehicle. It was assumed that the gap thickness would be equal to 0.2 mm and the length of a bond would be 30 mm. The internal diameter of the tubes was 14 mm and 18 mm, whereas the inserts’ external diameter was 13.6 mm and 17.6 mm. Their surface has been subjected to mechanical treatment with sand paper starting from 240 grit up to 400. The adhesives used were EA 3425 and EA 9466 cured at 80 °C for 2 h. The results showed that the glass beads method provides more consistent and better results as compared to the geometrical (mechanical) method. Further study in the area of fatigue and interfacial failure modes could be useful.

Development of Digital Control Algorithms for the Mechatronics System Drives of Reversing Plate Mill Stands

Expanding the plate mill product range implies the improvement of control algorithms for the mechatronics control system drives of the reversing stands. The most important objectives include increasing the accuracy of geometric dimensioning and tolerancing, as well as improving the profile and surface flatness of rolled pro­ducts. The structure explaining the automatic ROLL-GAP CONTROL concept is provided, which allows controlling the thickness and gap between SMS-Demag AG rolls. This concept is implemented in the '5000' mill stand of Magnitogorsk Iron and Steel Works. The structural diagram of the automatic gauge control system (AGS) is presented. The functional diagram of the hydraulic gap control (HGC) system is presented, which includes a fast proportional control channel and a relatively slow integral position control channel. The principle of automatic thickness control is discussed, implemented in the automatic gauge control (AGC) system of the mill stand TCS controller. The diagram and dependences are prepared for the calculation of the nonlinear thickness controller parameters. The functions of the RAC regulator are described, intended for compensation of the tensile difference (gap spacing) at the mill stand sides. The dynamic impact compensation system functions are considered. The removal of the roll bending and deformation control signals is substantiated. The disadvantages of AGC are noted for sheets with a thickness below 10 mm. The most dangerous case is the tearing of metal fragments from the rear sheet side caused by the incorrect operation of the gauge control system. A method for hydraulic gap control is proposed based on the fast increase of the roll gap in the rear part of the rolled sheet during the last passage when rolling thin sheets. The results of experimental studies made on the '5000' mill are presented. The efficiency of the proposed control method has been confirmed. The oscillograms of signals are presented characterizing thickness variations. HGC and AGC systems with the proposed adjustments are proven to provide high-accuracy hydraulic position control and thickness control along the sheet length and width.