• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.67-73
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• 2001

This paper aims at developing a torque model for the high-speed tapping with small-diameter taps. As recent industries such as automobile and information technology grows, taps smaller than 5mm in diameter are needed much more. In that occasion, the friction force between a tap surface and a workpiece plays much more important role in the tapping torque than in he larger tapping. Tapping mechanism was analysed based on the tap geometry. It has two steps : one is a forward cutting composed of the chamfered threading and full threading and the other is the backward cutting. The torque by the cutting force in the chamfered threading is calculated using the cutting area and the specific cutting force while the torque by the friction force, which is rather dominant than the cutting force both in the full threading and in the backward cutting, is calculated using the normal force on the threads and the friction coefficient. The experiment has shown that the results by the proposed torque model fit quite well with the acutal measurements within the error of 10%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.304-307
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• 2002

High speed machining was accomplished. through the technological advances which covers the whole field of mechanical industry. But tapping have many troubles because of its complicate cutting mechanism, for example. tool damage, chip elimination and synchronization between spindle rotation and feed motion. But High speed tapping is so important that it marches in step with the flow of the times and make improvement in the productivity. In this paper we analyze mechanism of high speed synchronized tapping with the signal of tapping torque and spindle speed obtained through the newly developed high speed tapping machine(NTT-30B). We made an experiment with this machine on condition of various speed from 1000rpm to 10000rpm. As one complete thread is performed through the whole chamfer cutting, cutting torque increases highly in chamfer cutting, but smoothly in full thread cutting functioning of the threads guide. And the size of cutting torque according to spindle speed(rpm) was not enough of a difference to be conspicuous.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.315-318
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• 1997

In terms of productivity, the speed of machining process has been increasing in most of engineering part. But the tapping process does not reach at enough level compared with other machining processes because of its complicate cutting mechanism. In the high speed tapping process, the one of important elements is tool monitoring system to prevent tool breakage. This paper describes tool monitoring system by acoustic emission(AE) in the tapping process. We used 2 types of AE sensors in this test. The one is commercial sensor which is used in other machining monitoring system like polishing and the other is a self-fabricated sensor for this test. In this test we purpose to find out the frequency of AE signal in tapping process and verify the possibility of applying AE sensor in in-process tapping monitoring system. Also grasp of characteristic of tapping process by AE signal is handled.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.243-246
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• 2000

Productivty of tapping has been increasing through the tcchnological advances in synchronization between spindle rotation and feed motion even in the high spindle speed. However, not much researches have been conducted about tapping process because its complicate cutting mechanism. In order ta investigate the characteristics of the tapping process, this paper concentrates on the analysis of curting torque behavior during one cycle of lapping. As one completc thread is performed through the whole chamfer ercuttlng, cutting torque increases highly in chamfer cutting, but smaothly in full thread cutting Functioning of the threads guide. Cutting torque in backward cutting is smaller than in Sorwerd cutting due to only friction farce in against between the tool and workpiece. And torque behavior of a periodic Sine ripple-mark was identified during one revolution of a tap.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.4
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• pp.277-283
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• 2006

As the products such as HDD, Notebook, PDA, and Mobile Phone become smaller and thinner, the radius of threads as well as holes for assembling those products become smaller, even down to 1mm. To produce such small holes and thread efficiently, multi tapping is highly necessitated. However the multi tapping characteristics is not well known because its complicated cutting mechanism and thus the quality of the produced holes and threads is not well studied yet. In this paper, experiments have been conducted for small-radius threads using M2 and M2.6 and M3 cold forming tap to investigate multi tapping process using several useful signal such as torque and Z-axis encoder pulse. The surface and profile of the machined threads have been magnified and observed through a SEM.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.4
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• pp.307-314
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• 2016

Recently, demands on the tapping machine are increased due to the case of a cell phone is changed to metal such as aluminum. The automatic tool changer (ATC) is one of the most important devices for the tapping machine related to the speed and energy consumption of the machine. To reduce the consumed energy and vibration, the dynamic modeling is essential for the ATC. In this paper, inverse dynamic modeling of a novel ATC mechanism is introduced. The proposed ATC mechanism is composed of a double four-bar mechanism with a circular tablet to generate continuous rotation of the tablet. The dynamic modeling is performed based on the Lagrange equation with a modeling for the contact between the four-bar and the tablet. Simulation results for various working conditions are proposed and analyzed for the prototype design. The dynamic modeling can be applied to determine the proper actuator and to reduce the vibration and consumed energy for the ATC machine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.1
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• pp.31-35
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• 2003

Switch box is metal box and used for electric wire pipe in building. In manufacturing switch box, we need 5∼6 press machines, 5∼6 dies, 1 tapping machine. and 7∼8 operators. What matters is rise of manufacturing cost and operators' reluctance of working. To solve this problem, we modified the pre-existing die and developed handling mechanism, which leads to improve the manufacturing process. After the research and development, we could reduce the number of machines and workers needed in the process; 2 press machines, 2 dies, 1 tapping machine, and 1 operator. That means we can save labor and the number of operators needed, reduce manufacturing cost, and get the effect of import replacement.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.881-886
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• 2003

In spite of its simple design, structure and operating mechanism, swing check valves are one of the critical components which adversely affect the safety of the nuclear power plants if they fail to function properly. Therefore, it is important to evaluate the performance condition of the swing check valves in safety-related systems. The performance characteristics of swing check valves include opening characteristics, the minimum required flow velocity, the pressure drop at design flow, the disc stability, and the effect of the upstream disturbances. Among factors to identify the performance of a swing check valve, a method to evaluate the opening characteristics and the minimum required flow velocity, which guarantees to fully open the disc and hold the disc without motion, are presented to determine the operating region of the swing check valve, such as stable, tapping, or oscillation. Based on the determined operating region and opening characteristics, the simple methods of wear and fatigue analyses of the specific parts of the valve are also described.

• Clinical and Experimental Reproductive Medicine
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• v.22 no.2
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• pp.155-161
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• 1995

The present investigation has been undertaken to elucidate the differentiation mechanism the uterus which is the environment of the embryo development, by demonstrating the role of ovarian steroids hormone in the decidualization of the pseudopregnant rat uterus. To determine the effect of ovarine steroids and artificial stimulation (trauma) on the differenciation of the uterine endometrium and decidualization for implantation, attempt was made to measure concentrations of serum estradiol($E_2$), progesterone($P_4$) and nuclear $P_4$ receptor in the traumatized and non-traumatized uterine tissue of the pseudopregnant rat. The results obtained are as followings : The concentration of serum $E_2$ on day 9(implantation stage) was similar in both of intact pseudopregnant rat(47.63pg/ml) and normal pregnant rat(40.71pg/ml). And among the treated groups, $E_2$ concentration was highest in the $E_2$ treated group in comparision with intact control group(relative value; 73.27%). The concentration of serum $P_4$ was also highest in the $P_4$ treated group(23.12pg/ml). Relative value of $P_4$ treated group in comparision with intact group(24.88pg/ml) was 92.93%. The nuclear $P_4$ receptor levels in the artificial traumatized groups were higher compared with the non-traumatized control groups. This study, therefore, clearly demonstrates that the methods for inducing pseudopregnant (vagina tapping;120/min) and inducing decidualization(oil injection; 0.1ml/uterine horn) appear to be effective, $P_4$ appears to be effective in the differenciation of the uterine endometrial tissue for the implantation process. Concentration of serum $P_4$ seems to be well correlated with the level of the nuclear $P_4$ receptor during the early embryo development. These results seem to be well correlated with ALPase activities in the normal and pseudopregnant rat uterus shown in the previous study.