Tantrapiwat, Akapot

Preferred name

Tantrapiwat, Akapot

Alternative Name

Tantrapiwat, A.

Main Affiliation

School of Engineering

akapot.ta@kmitl.ac.th

Now showing 1 - 6 of 6

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A variable search technique for multiple control valves used in melt modulation during injection molding
(2010-12-01)
Coulter, John P.
;
Tantrapiwat, Akapot
A variable search technique was investigated for use with a melt modulation system with multiple control valves. The method was developed in order to obtain an optimum solution which determines the positions of all valves. It was shown that not all valve angles in the system had to be determined, as only certain significant valves needed to be fine tuned during the searching process. It was also shown that the valve position and location were greatly dependent on the cavity and runner configurations. Once the valve control variable search method had been established, a series of family mold models was created and analyzed using MoldFlow. Instead of using the default runner from the software, a modification of the 3D models was made in order to embed melt modulation valves. The result showed that within a limited number of trials, an optimum solution can be obtained. The number of searching trials can also be reduced by applying different search gains and changing certain appropriate initial values. © 2010 by ASME.
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Development of multiple melt modulation valves for enhanced injection molding
(2010-12-01)
Tantrapiwat, Akapot
;
Coulter, John P.
New melt modulation system with multiple control valves was successfully developed to facilitate melt control in cold runner based injection molding. The entire valve mechanism and port geometry were significantly improved. The new valve gave better control characteristic and can be made inexpensively. Valve driving mechanism was also redesigned to be more compact and easy to be installed in a limited mold space. It allows four control valves to be placed in the same mold in which only two original valves were able to fit. The four valve melt modulation performed on a runner system that the effect of melt flow from each valve was influenced by all other valves. The interaction between four valves caused complicated behavior and also a difficulty to establish valve control parameters. A reciprocal search method was utilized and able to determine valve control variables within a reasonable number of trials. Experimentation was done on a potential case study that included both family molding and weld line positioning problems. As a part of the outcome, a simple gain modification was developed and able to find an optimum solution. The technique was carried out in both traditional fixed angle and new developed Bang-Bang control methods. The results shows that melt modulation system with multiple control valves was able to effectively control melt behavior and enhanced filling process. © 2010 by ASME.
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Development of a vision based mapping in rubber tree orchard
(2018-08-13)
Kunghun, Worawut
;
Tantrapiwat, Akapot
A mapping method for rubber tree orchard was developed using an image processing. Because of high labor cost and continuous dropped price of natural rubber in the past years, the rubber tree farmers are struggled to maintain profit and their productions. Automation technology in agriculture can be a solution to cut down the production cost which comprises of a large share in harvesting labor expense. To create such automation, the autonomous and orchard mapping are the first challenges. Due to the natural rubber industry is popular in particular part of the world, mostly in South East Asia, the vision mapping and autonomous on rubber tree orchards have not been done widely. This research aims to develop a model of vision mapping system which is suitable to the rubber tree plantations based on the common farming platform in Thailand. The vision model was designed to use single camera capturing calibrated targets which were placed on the rubber tree trunks. The length of the target from the captured image was then calculated in order to estimate the distance and position of the camera in relation to the orchard geometry. Because the larger size of the targets results in higher accuracy, however one large single target is not practical for installation on the trees, two separated targets technique was created. Three different lengths, 0.3, 0.5, and 0.7 meters, of separated targets were examined during the experiments. Percent error distances of target to camera, Z-direction, and target to center of camera, X-direction, were evaluated and also their uncertainties. The results have shown that largest target gave small error uncertainties, but the percentages of errors are quite similar among all sizes of targets. Because the sizes of the errors are proportion to the sizes of the targets, the percentage errors therefore adapt to the sizes of the targets. The experiments were carried out at 1-5 meter distances between target and camera that were set to cover the normal 3 meter distance between tree rows. It showed that the vision mapping can perform at about 8 cm repeatability in z-direction and about 13 cm in x-direction. This magnitude of errors seems to be large but it is actually practical for the orchard autonomous which is usually designed for low speed vehicle working on a large area.
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Dynamic feed rate in multiple independent spindles cnc milling machine for orthotic insole manufacturing
(2019-12-01)
Watasuntonpong, Pongpun
;
Pimsarn, Monsak
;
Tantrapiwat, Akapot
Diabetic foot ulceration can be prevented in case of the high plantar pressure being reduced and transmitted from ultimate stress point to the total area of plantar tissues. Custom-Made Insole (CMI) is one of the practical techniques to reduce ultimate stress on the patient’s foot. By employing the CAD/CAM technology, CMI for diabetic patients can be made fast and cost effective in comparison to the conventional method. In this research, there were two major improvements which made the CMI manufacture even faster and cheaper. First, a foot sole surface impression machine was developed to be compatible with the CMI configuration. The reusable foot sole impression machine can replace the traditional dispensable impression foam. An experiment was carried out to verify that pressure distribution on the impression surface was effective and comparable to the conventional method. The second improvement was the implementation of multiple independent spindles CNC system on the CMI cutting process. The configuration of multiple cutting tools and design cutting paths were investigated. In addition, the optimum cutting parameters were established using cutting force criteria. The relationship between cutting force and axial depth of cut was used to assign the feed rate. Because the feed rate which relates to the Z-direction can be varied among all spindles, two different techniques, fixed and dynamic feeds, were applied and compared. On average, the fixed feed technique can cut a pair of insole within 32 minutes, while dynamic feed can produce within 29 minutes. Overall both foot sole surface impression machine and multiple independent spindles CNC milling machine can cut down the production time to only 60% of the time used in typical CAD/CAM system, and 20.8% of the time used in conventional method.
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Study on wind energy potential for agricultural water pumping system in the middle part of Thailand
(2018-08-14)
Prabkeao, Chamlong
;
Tantrapiwat, Akapot
A study on wind powered water pumping system aimed for agriculture was carried out in the middle part of Thailand. In this alluvial plain, wind energy potential was determined by making a survey on 21 observation sites. The survey was made in a period of one year, and it has shown that this region locates in a clam climate zone with average wind speeds at about 2 m/s. A wind turbine-water pumping system was installed and evaluated for its performance and efficiency. The result has shown a linear relationship between water discharge capability and the wind speeds. Due to the type of turbine and low wind speed in this region, the system efficiency turned out to be minimal, yet it was practical because the wind power was free. A simple cost analysis from the survey data also has shown that using a wind turbine in this region will be worthwhile when it can be operated for about two decades.
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Navigation of autonomous vehicle for rubber tree orchard
(2019-10-25)
Kunghun, Worawut
;
Tantrapiwat, Akapot
;
Chaidilokpattanakul, Phudit
This research has studied the navigation of autonomous vehicles in rubber tree orchards. It was emphasised on the rubber tree plantation in Thailand. Due to the high labour costs in the rubber industry and the demand for natural rubber has continued to decline over the past several years. The farmer were struggled to reduce the labour costs in production. The development of autonomous vehicle technology in rubber plantation can be a way to ease the production costs, such as reducing the amount of labour in fresh latex harvesting. This work was aimed to develop algorithm of a vision system for replacement of expensive sensors used in typical autonomous vehicles. The vision system model was implemented using only one camera installed on the vehicle to search for calibrated targets which were put on the rubber tree trunk. There were two important parameters, tree row offset and target distance, which were concerned when determining the performance of the autonomous vehicle in the rubber tree orchards. In order to evaluate the accuracy of the system, a set of experiments was conducted at a distance of 1-5 meters between the target and the camera. The results were compared between the controlled environment in the laboratory and the uncontrollable environment in the real rubber plantation.

Tantrapiwat, Akapot

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