Tapping Process Research Articles

Tapping Tool Life Assessment in Vertical Milling Centre in the CNC Production Centre

Tapping process in Computer Numerical Centre, is a key for the process because of its difficult to hold the close tolerance. During this study different types of tapping tool manufacturer have taken with same tapping tool material specification for the consideration. And also to find the relationship between the previous operational performances with tool and its parameter influence in the computer numerical control system has also taken for the consideration. During drilling process the new drill bit (drill bit 4) have higher tool life than the regained tool bits (Drill bit 1, 2 & 3). During tapping process, Emuge tool 2 and Emuge tool 3 have has higher production rate such as 434 and 356 components respectively. This Emuge tool 2 and tool 3 have previous working tool in the drilling process is drill bit 4 (New Drill Bit). Which has improved the surface roughness than the other drill bit. Due to reduced surface roughness causes the taping tool to ease in there processing which resulted in the higher production rate in tapping tool than the other conditions.

Research on the influence of a new tap drill geometry on C45, 42CrMo4 and X5CrNi8 steel processing

The shearing of the chips in a blind hole thread presents a particular problem in machining industry. The tap geometry plays an important role in the tool's durability, influencing the forces during the tapping process and also the way in which the chips are evacuated. This paper analyzes the influence of the tap geometry on the cutting of materials such as C45, 42CrMo4 and X5CrNi8. An adequate geometry will extend the tap durability by controlling the chip when the tap reverses while still engaged in the tapping process. It relates to the improvement of a spiral tap drill, which discharges chips towards the shank via a helical flute. The article contains details about the tap geometries and the results obtained in this research. Based on the results obtained in this research, the purpose of this paper was achieved. The tap durability was improved, the chip deposition on the rake surface was reduced and the torsion torque has a smaller value compared to the standard tap geometry.

Vision-based investigation on the ash/slag particle deposition characteristics in an impinging entrained-flow gasifier

Coal gasification is widely used for chemical production as well as energy generation, and slag tapping process is crucial to entrained-flow coal gasification, before which particle deposition play an important role in slag formation. In order to investigate the slag tapping under special or abnormal operating conditions, the ash/slag particle deposition and ash/slag layer behavior characteristics have been studied based on a bench-scale impinging entrained-flow gasifier. High temperature endoscopy combined with high speed photography is applied to obtain images inside the gasifier and image processing techniques are used to distinguish the object from the high brightness background. The results show that an ash/slag deposition layer is formed under low operating temperature. In the case of particle deposition: High temperature particle (HTP) with medium size would slide on ash/slag layer after impacting, low temperature ash/slag on the deposition layer adheres on the particles and detach from the deposition layer together. HTPs with big size would attract low temperature ashes while travelling in gasifier space and ash/slag surface after impact, then form a low temperature particle (LTP) group with high temperature core and detach from the basic ash/slag layer. LTPs with big size and high space speed would impact and embed into the ash/slag deposition layer, then particle temperature rises while particle volume decreases. The embedded particles hardly detach from the basic layer. The low temperature ash/slag deposition layer would detach from the old slag layer on refractory wall, and the detachment of ash/slag layer is mainly classified into three typical patterns according to the behaviors of the detach process: detach after sliding pattern, detach after tilting and shaking pattern, detach after warping and fracturing pattern. Detachment after warping and fracturing is the commonest pattern of ash/slag deposits behavior that has been observed. Due to the huge volume of detached pieces, it could be the major source of slagging under abnormal operating condition. Under certain extreme conditions, slag tap hole would be blocked by the bridging of huge ash/slag deposits pieces and leads to overpressure of gasification chamber and slagging failure. In industrial applications, the results of this study would be the theoretical support for the suggested minimum load and suggested feeding period of the gasifier during the unique online pressurized continuous coal-water slurry feeding technique of the opposed multi-burner (OMB) gasification.

Numerical Simulation and Experimental Research on Cold Form Tapping Process of Internal Thread

During the cold form tapping process of internal thread in high-strength-steel, the effect of bottom-diameter, extrusion speed, friction factor and extrusion times on extrusion temperature and torque have contributed to tap wear, break and manufacturing quality. The process of cold form tapping of internal thread for Q460 high-strength-steel is studied through numerical simulation and experimental research. The effect of different processing parameters, including the bottom-diameter, extrusion speed, friction factor and extrusion times, on temperature and torque during the process of cold form tapping of internal thread are analyzed to provide new basis for further choosing optimized processing parameters. The simulation and test results show that obvious stress-strain and higher temperature zone focuses on working area during the cold form tapping of internal thread for Q460 high strength steel. The simulation value is slightly lower than the measured value and the error is no more than 20%. With the increase of bottom-diameter and extrusion times and the reduction of extrusion speed and friction factor, the extrusion temperature and torque will decrease.

Reinforced lubrication of vegetable oils with graphene additive in tapping ADC12 aluminum alloy

This paper studied the effect of graphene additive on the lubricating capacity of vegetable oils. The castor oil, rapeseed oil, and corn oil were chosen as base oils, and ultrasonic agitation was used to prepare the graphene in vegetable oil suspensions with six different mass fractions. These suspensions were utilized as minimum quantity lubrication (MQL) lubricants during the internal tapping process of ADC12 aluminum alloy. Tapping torque and thread surface morphology analyses were applied to evaluate the lubrication performance. The results showed that the pure castor oil MQL achieves the lowest average tapping torque in all the base oils. Meanwhile, the use of graphene additive can significantly reduce the tapping torque, and this torque reduction shows a nonlinear relationship with the graphene mass fraction. As an overall trend, the 0.5% mass fraction is the optimum concentration, which decreased the average torque by 0.64 Nm (11.4%), 1.6 Nm (16.4%), and 1.7 Nm (17.7%) compared with pure castor oil, rapeseed oil, and corn oil, respectively. Moreover, the scratching defects on the thread surface were obviously reduced with the application of graphene additive. This torque-reducing and anti-wear effect could be related with the graphene-related friction films formed on the metal surfaces. The research verified that the vegetable oil-based graphene suspension can be used as a substitute for the conventional mineral oil-based metalworking fluids.

Type I IFN and not TNF, is Essential for Cyclic Di-nucleotide-elicited CTL by a Cytosolic Cross-presentation Pathway

Cyclic di-nucleotides (CDN) are potent stimulators of innate and adaptive immune responses. Cyclic di-AMP (CDA) is a promising adjuvant that generates humoral and cellular immunity. The strong STING-dependent stimulation of type I IFN represents a key feature of CDA. However, recent studies suggested that this is dispensable for adjuvanticity. Here we demonstrate that stimulation of IFN-γ-secreting CD8+ cytotoxic T lymphocytes (CTL) is significantly decreased after vaccination in the absence of type I IFN signaling. The biological significance of this CTL response was confirmed by the stimulation of MHC class I-restricted protection against influenza virus challenge. We show here that type I IFN (and not TNF-α) is essential for CDA-mediated cross-presentation by a cathepsin independent, TAP and proteosome dependent cytosolic antigen processing pathway, which promotes effective cross-priming and further CTL induction. Our data clearly demonstrate that type I IFN signaling is critical for CDN-mediated cross-presentation.

Electrophysiological signatures of phonological and semantic maintenance in sentence repetition

Verbal short-term memory comprises resources for phonological rehearsal, which have been characterized anatomically, and for maintenance of semantic information, which are less understood. Sentence repetition tasks tap both processes interactively. To distinguish brain activity involved in phonological vs. semantic maintenance, we recorded magnetoencephalography during a sentence repetition task, incorporating three manipulations emphasizing one mechanism over the other. Participants heard sentences or word lists and attempted to repeat them verbatim after a 5-second delay. After MEG, participants completed a cued recall task testing how much they remembered of each sentence. Greater semantic engagement relative to phonological rehearsal was hypothesized for 1) sentences vs. word lists, 2) concrete vs. abstract sentences, and 3) well recalled vs. poorly recalled sentences. During auditory perception and the memory delay period, we found highly left-lateralized activation in the form of 8–30 Hz event-related desynchronization. Compared to abstract sentences, concrete sentences recruited posterior temporal cortex bilaterally, demonstrating a neural signature for the engagement of visual imagery in sentence maintenance. Maintenance of arbitrary word lists recruited right hemisphere dorsal regions, reflecting increased demands on phonological rehearsal. Sentences that were ultimately poorly recalled in the post-test also elicited extra right hemisphere activation when they were held in short-term memory, suggesting increased demands on phonological resources. Frontal midline theta oscillations also reflected phonological rather than semantic demand, being increased for word lists and poorly recalled sentences. These findings highlight distinct neural resources for phonological and semantic maintenance, with phonological maintenance associated with stronger oscillatory modulations.

Research on deadman state during tapping process

ABSTRACTIn this paper, a deadman state model is established. According to the actual operation parameters of 5500 m3 blast furnace (BF) in Shougang Jingtang United Iron and Steel, the influence of taphole depth, deficient iron amount and salamander depth on deadman state is discussed. Meanwhile, the relationship between deadman state and differential pressure of BF is analysed. The results show that deadman of 5500 m3 BF is floating during regular production and the range of floating height is 0.23–0.30 m. When the mud mushroom cannot be formed or cracks during tapping process, the range of floating height is 0.38–0.45 m. The upward movement of deadman can result in the reduction of coke size and porosity, which is one of the key factors that causes holding hot blast.

Segmented and mathematical model for 3D FEM tapping simulation to predict the relative torque before tool production

The conventional tapping tool development consists of costly investigative experiments. The development time and cost can be significantly reduced, if these test were replaced by virtual analyses, before the tool prototypes are fabricated. Compared to turning, milling and drilling, in which many valid simulative methods have been established, the tapping process has been given rather little research attention. In this paper an approach is presented, which could be used during the design phases, to predict the relative torque, so that resources, energy and cost can be saved. Based on a simulated reference model, which is in good agreement with corresponding experimental results, the problem of a long computing time could be solved by using a proper segmentation method, which offers a process simulation along the whole chamfer length. With an according mathematical model, the discontinuous torque curve could be summarized to a total load cycle.

Numerical Analysis on Flow Behavior of Molten Iron and Slag in Main Trough of Blast Furnace during Tapping Process

The three-dimensional model was developed according to number 4 of the main trough of blast furnace at China Steel Co. (CSC BF4). The k-ε equations and volume of fluid (VOF) were used for describing the turbulent flow at the impinging zone of trough, indicating fluids of liquid iron, molten slag, and air in the governing equation, respectively, in this paper. The pressure field and velocity profile were then obtained by the finite volume method (FVM) and the pressure implicit with splitting of operators (PISO), respectively, followed by calculating the wall shear stress through Newton’s law of viscosity for validation. Then, the operation conditions and the main trough geometry were numerically examined for the separation efficiency of iron from slag stream. As shown in the results, the molten iron losses associated with the slag can be reduced by increasing the height difference between the slag and iron ports, reducing the tapping rate, and increasing the height of the opening under the skimmer.

Application of the Acoustic Emission Method for Diagnosis of On-Load Tap Changer

Abstract This paper provides an example of the application of the acoustic emission (AE) method for the diagnosis of technical conditions of a three-phase on-load tap-changer (OLTC) GIII type. The measurements were performed for an amount of 10 items of OLTCs, installed in power transformers with a capacity of 250 MVA. The study was conducted in two different OLTC operating conditions during the tapping process: under load and free running conditions. The analysis of the measurement results was made in both time domain and time-frequency domain. The description of the AE signals generated by the OLTC in the time domain was performed using the analysis of waveforms and determined characteristic times. Within the time-frequency domain the measured signals were described by short-time Fourier transform spectrograms.

Determination of an adequate geometry of the flanged hole to perform formed threads

In this work, the flanged hole is adopted as a potential solution to increase the number of formed threads in the case of sheet metal part. To achieve an adequate initial tap hole for tapping process, the final shape of the flanged hole was analyzed by 2D finite element (FE) simulations. An adequate range of the clearance j between the die and the punch of the hole-flanging process was identified for which formed threads are performed on a vertical flange with more substantial and uniform thickness as well as an important height. To ensure that the selected flange is free from fracture, 3D FE model was developed using Gurson-Tvergaard-Needleman coupled approach. Experiments were carried out in order to validate the numerical results and to analyze the geometry of formed threads performed on the selected flanged hole and the drilled hole.

Influence of tool cooling on thrust forces in tapping operations of reinforced polyamide

The machining with compressed air cooling has been identified as an environmentally conscious process. Its good performance has been achieved in materials as titanium alloys or aluminum alloys, but composites have not been explored. This work presents a first study related to evolution of thrust forces during the tapping process in reinforced polyamide with glass fiber, in particular PA66-GF30, when the tool cooling is considered. The experimental methodology was carried out by tapping operations in plates of PA66-GF30, using a drilling center. The experimental tests were executed using compressed air cooling by means of a vortex-tube cooling, in dry. Taps are of high-speed-steel with cobalt as base material and with coating; their geometry and dimensions are M12x1.75 mm. Outcomes obtained confirm that the methodology is appropriate in the tapping process of PA66-GF30. The tool cooling provides a reduction of thrust forces, although it is conditioned by type of tap and the coating.

Effect of coefficient of friction at the sliding zone of chip-tool interface on chip curl diameter and secondary shear zone thickness during tapping process

Effect of coefficient of friction at the sliding zone of chip-tool interface on chip curl diameter and secondary shear zone thickness during tapping process

Industrial research on the high-temperature modification of Basic Oxygen Furnace slag with solid waste compound

Basic Oxygen Furnace slag, the main by-product of steelmaking process, presents still low utilization rate due to its limitations as a partial replacement for cement. The previous fundamental research demonstrated that the slag exhibits the modulated composition and improved property via reacting with the modifier at high temperature. Herein, an industrial modification technique has been studied at the scene of the 120t steelmaking converter to improve the technical feasibility, security and compatibility with the existing steelmaking process. The slag characterization indicates that the sufficient reaction between the huge amounts of slag and modifiers occurs during the slag tapping process, which is contributed to the optimal operations and specific modifiers treatment. The modified slag tailings show the dramatically improved grindability with high availability. Moreover, the 3d and 28d active index of the cement paste consisting of modified slag tailings and cement in 3:7 wt ratio are about 20% and 12% higher than that of the system with the pristine tailings, respectively. Therefore, the modification of Basic Oxygen Furnace slag taking advantage of waste heat and solid waste as modifier is a feasible industrial technique to accelerate the cleaner production in steelmaking industry.

Mechanics of tapping process with emphasis on measurement of feed error and estimation of its induced indentation forces

Feed error induced by the mismatch between the spindle motor and Z-axis motor of the machine can significantly influence the cutting loads during thread tapping process. In this paper, a comprehensive study, which allows predicting the feed error-induced force together with measuring the actual tapping feed error, is presented by establishing simplified methods. Convenient experimental setup and procedure are first proposed to measure the actual feed error by using a laser tachometer along with a laser interferometer, followed by modeling the contact status between the tap flank and workpiece under feed error as an indentation effect, under which the corresponding indentation force is derived as a simplified proportional function of the indentation volume by using the basic principle of contact mechanics. Identification scheme is also developed to determine the proportional coefficient, i.e. the indentation force coefficient. Total tapping forces are obtained by summing cutting forces related to material removal mechanism and the indentation forces associated with feed error. Experimental verifications have been carried out to validate the proposed methods.

EFFECT OF KINEMATIC OF SCREWING ON QUALITY OF THREADED CONNECTIONS

Purpose. Research of the influence of the process parameters on the quality of threaded connections, notably, thread formation axial force on the opposite sides of the roots. Determination the thread formation axial force for screws with a wide groove. Design/methodology/approach. In a paper it is shown, that action of uncompensated thread formation axial force increases the defects and imperfectness of the strengthened layer. Proposed the theory about changes in the traditional self-stretching thread-formation method on the implementation process with a constant axial force. The external axial load must be equal to the largest axial component force of the thread-formation. The method uses the slip-line method with a model taking into account the interaction between two consecutive formed threads and enables the mean pressure on the thread flank to be obtained as a function of the formed thread height. From these results and a knowledge of the forming screw end geometry, an analytical method is proposed for the maximum axial force, the physical phenomena of the displacement of material in the tapping process is illustrated and the significantly influential parameters highlighted. Findings. This study proposes an analytical model based on a previous study concerning radial penetration of a rigid acute wedge into a perfectly plastic material. An experimental study seeks to determine the optimal lead hole on the work piece for an M8 screw. The experimental results are compared favorably with the results of the analytical study in order to validate the forming screw model. Originality/value. It is shown the influence of the geometrical parameters of the thread forming screw and of the work-piece on the axial force, and the influence of the process parameters on the quality of threaded connections. This sets limits on the forming axial force and conserves a sufficiently well formed thread shape for good stripping resistance. The experimental results are compared favorably with the results of the analytical study in order to validate the forming screw model.

Comparison among different vegetable fluids used in minimum quantity lubrication systems in the tapping process of cast aluminum alloy

Nowadays, cooling fluids are the great environmental issue, because they consume a considerable amount of water and can pollute natural water sources for decades when they are discarded and disposed of irregularly. Based on this, the Minimum Quantity Lubrication technique, that uses low amounts of fluids, has been used in drilling processes since 1990 and is a major breakthrough in reducing the use of cutting fluids. In this study, three different Minimum Quantity Lubrication cutting fluids were tested and compared with emulsions in cut and form tapping processes. A Full factorial design was performed to identify the significant effect of the type of oil, cooling/lubrication system and cutting/forming speed on the torque value of the tapping processes. A steering system carcass manufactured by A306 cast aluminum alloy was used as a workpiece in the tapping operations. The results showed that fluid A (ECOCUT) in the Minimum Quantity Lubrication system has a high potential to reduce torque value while minimizing the friction and can avoid that tools break, in some situations. Furthermore, form tapping was found to be a suitable alternative, since it does not generate chips, which reduces costs with recycling, storage, and waste disposal.

Identification and functional characterization of HbOsmotin from Hevea brasiliensis

Latex in the laticiferous cell network of Hevea brasiliensis tree is composed of cytoplasm that synthesizes natural rubber. Ethylene stimulation of the tree bark enhances latex production partly by prolonging the duration of latex flow during the tapping process. Here, we identified an osmotin-like cDNA sequence (HbOsmotin) from H. brasiliensis that belongs to the pathogenesis-related 5 (PR-5) gene family. The HbOsmotin protein is present in the lutoids of latex in H. brasiliensis, whereas in onion epidermal cells, this protein is predominantly distributed around the cell wall, suggesting that it may be secreted from the cytoplasm. We investigated the effects of exogenous ethylene on HbOsmotin transcription and protein accumulation in rubber latex, and further determined the protein function after osmotic stress in Arabidopsis. In regularly tapped trees, HbOsmotin expression was drastically inhibited in rubber latex after tapping, although the expression was subsequently recovered by ethylene stimulation. However, in virgin plants that had never been tapped, exogenous ethylene application slightly decreased HbOsmotin expression. HbOsmotin overexpression in Arabidopsis showed that HbOsmotin reduced the osmotic stress tolerance of the plant, which likely occurred by raising the water potential. These data indicated that HbOsmotin may contribute to osmotic regulation in laticiferous cells.

Combination of friction drilling and form tapping processes on dissimilar materials for making nutless joints

In this article, a new method for the rapid and economical production of ‘nutless’ bolted joins is presented, using a combination of two hole-making techniques, namely, form drilling and form tapping. The combined method achieves a quick way for the production of threaded holes on couples of dissimilar metal alloys, as it is the case of steels and aluminium alloys. After the simultaneous form drilling on the aluminium–steel pairs and followed by form tapping, a fastener can be introduced and screwed for achieving a tight bolted joint, without any necessity of nut. However, form drilling and threading are performed consecutively in the same machine tool, reducing the whole process time. The process parameters were studied for reducing the gap between surfaces and producing a good cup for making the posterior threading. Then, mechanical testing of several test pieces resulted in a similar behaviour than traditional bolted joints. Finally, corrosion tests were performed for a better understanding of the joint manufactured. In this way, savings in time and money are derived from the application of the approach. Target markets for the new approach are the light boilermaking industry in order to eliminate either welding beads or classical bolted joints using nuts.