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Sulas G.Borkar et al. / International Journal of Engineering Science and Technology (IJEST) IMPROVEMENT IN CONVENTIONAL WATER JACKET METHOD IN MOULD COOLING USING HEAT PIPE SULAS G.BORKAR1 1PG Student Department of Mechanical Engineering, G. H. Raisoni College of Engineering Nagpur, MS (India) R.S.SHELKE2 2Assistant Professor, Department of Mechanical Engineering, G. H. Raisoni College of Engineering Nagpur, MS (India) Abstract: Die casting moulds and injection moulding are cooled by conventional water jacket method. Cooling of mould is very essential for the purpose of quality of parts and cycle time. The conventional water jackets methods used are having many disadvantages, due to which the effect of mould cooling is not optimum. Hence a technique which can overcome all the disadvantages and become optimum emerged. The main aim of this proposed work is to improve conventional water jackets methods in mould cooling by the application of heat pipe. Heat pipe plays an very important role in such situations, and shows effective results, there by improving the conventional water jacket method in mould cooling. It transfers heat many times faster than pure copper. Keywords: Conventional water jacket, mould cooling, heat pipe. 1. Introduction Plastics are the synthetic organic materials which can be moulded into any desired shape when subjected to heat and pressure. They are a group of materials when heated can be formed into a variety of useful articles by moulding and casting. Plastics have been increasingly accepted for modern engineering application because of the fact that plastics are attractive materials and offer many advantages in weight, cost, moisture, strength, and chemical resistance. Moulding is the most common method used in the fabrication of plastics. Moulding processes are based on the fact that when the plastic is heated, it will soften to a viscous liquid that can be forced into a mould, where it solidifies of desired shape. Injection moulding and die casting are the most common methods in the manufacturing of plastics . 2. Methods of casting 2.1 Die Casting: - Die casting is the art of rapidly producing accurately dimensioned parts by forcing molten metal under pressure into split metal dies which resemble a common type of permanent mould. Within a fraction of second, the fluid alloy fills the entire die. Because of the low temperature, the casting solidifies quickly permitting the die halves to be separated and the casting ejected. The advantages of die casting practice lies in the possibility of obtaining castings of sufficient exactness and in the facility for casting thinner sections that cannot be produced by any other casting methods. With the help of die casting, very high rate of production is achieved. 2.2 Injection Moulding: - Injection moulding is the most widely used method of producing parts of thermoplastic as well as thermosetting resins. The process resembles the hot chamber die casting of metals. The die, split to allow removal of the solidified product is kept shut, with an appropriate press force and ejectors are provided for removing the moulded component. Injection moulding and die casting moulds are cooled by conventional water jacket method. In plastic injection mould, cooling system plays a very important role for the purpose of quality and productivity of the ISSN : 0975-5462 Vol. 4 No.04 April 2012 1576 Sulas G.Borkar et al. / International Journal of Engineering Science and Technology (IJEST) moulded part [1]. In plastic injection moulding the function of the cooling system is to provide thermal regulation in the injection moulding process. When the hot plastic melt enters into the mould impression, it cools down and solidifies by dissipating heat through the cooling system [2]. 2.3 Conventional Method The conventional water jacket method is used for cooling the moulding processes. The conventional water jacket method is used in conjunction with baffles, blades and offers various disadvantages. Limitations of Conventional Method The conventional water jacket method used for cooling the moulding processes is having many disadvantages. They are as follows. 1. Heat transfer with water jacket takes place with laminar flow, which is very low as compared to heat transfer to turbulent flow. 2. Hot spots are produced due to inability of water jacket to cool the in accessible areas of mould 3. Increased cycle time due to slow cooling. 4. Rejection of parts due to defects such as Sink marks, pulling and spotting that takes place due to insufficient cooling. 5. Increased maintenance and operating cost as there is a tendency of scale formation, calcium deposits and clogging of ports in water jacket cooling system. Hence there is a need of a technique which can overcome all these disadvantages emerged. The solution for above problem is with the application of heat pipe in conventional water jacket method in mould cooling. 3. Proposed Method In this method it is suggested to use heat pipe in conventional water jacket method. 3.1 Heat pipe Heat pipe is a heat transfer device specifically designed for optimal performance in plastic injection moulds and dies for the die casting industries .The heat pipe consist of vacuum tight copper tube containing a wick and a non toxic working fluid .The two ends of heat pipe perform distinct functions, one end is evaporator and other end is a condenser. In heat pipe thermal energy is gathered at the evaporator end vaporizing the working fluid. The vapour then travels through the heat pipe to the condenser end. At the condenser end the vapour condenses back into a liquid giving up its latent heat in the process. To complete the cycle the condensed liquid then travels along the wick, via capillary action back to the evaporator section. This process repeats itself continuously, transferring heat many times faster than pure copper. Fig3. 1: Heat Pipe. Heat pipe is a device which works as an excellent heat conductor enables very intensive heat transfer from the area with higher temperature to the area with lower temperature [3]. Among the various cooling techniques, heat pipe technology is emerging as a cost effective thermal design solution due to excellent heat transport efficiency and capability [4]. Cooling of electronics is one of the major fields of applications for the heat pipes especially in notebook computers and telecommunications applications [5]. 3.2 Heat pipe orientation The performance of heat pipe depends upon various factors such as its diameter, length, application (how and where the heat pipe is used) and its orientation [6]. The various orientations performed for heat pipe are as follows ISSN : 0975-5462 Vol. 4 No.04 April 2012 1577 Sulas G.Borkar et al. / International Journal of Engineering Science and Technology (IJEST) 1. Horizontal orientation 2. Inclined orientation 3. Vertical orientation Out of these orientations heat pipe gives better thermal performance in horizontal orientation: Fig 3.2 shows, heat pipe in horizontal orientation. The thermal performance of heat pipe is best in this orientation. Hence it is better to use heat pipes in this position in mould cooling. Fig 3.2: Heat pipe in horizontal orientation Fig.3.3 shows, heat pipes in inclined orientation. The thermal performance of heat pipes is less in this orientation than above orientation. Fig 3.3: Heat pipe in inclined Orientation Fig 3.4 shows heat pipes in vertical orientation. The thermal performance of heat pipes is less in this orientation than the above two orientations. 3.3 Heat Pipes in Moulds Heat pipe is available in a variety of standard lengths and diameters, heat pipes are used in cores, core slides, cavities and other areas of mould or die requiring cooling or controlled temperatures. In moulds, heat pipes are available-le in two temperature ranges. (i) For Injection Moulds: - Heat pipes having temperature range from +50C to +2000C. The main application of these types of heat pipes are in injection moulding, compression and transfer moulding. (ii) For Die Casting Dies: - Heat pipes having temperature range from +5 0C to +3500C. The main application of these types of heat pipes are in die casting. ISSN : 0975-5462 Vol. 4 No.04 April 2012 1578 Sulas G.Borkar et al. / International Journal of Engineering Science and Technology (IJEST) Fig 3.4: Heat pipe in vertical orientation The basic consideration of a suitable working fluid in the operating vapours temperature range is very important during the performance. Table 3.1 shows the different working fluids with their melting point and boiling point. It also gives suitable temperature range for different working fluids. To maintain the good quality, the temperature of the moulding must be appropriately set and precisely controlled. Table3.1 Medium Helium Nitrogen Ammonia Acetone Methanol Flutec PP2 Ethanol Water Toluene Mercury Sodium Lithium Silver Melting pt. (° c ) - 271 - 210 - 78 - 95 - 98 - 50 - 112 0 - 95 - 39 98 179 960 Boiling pt. at atm. pressure (° c) - 261 - 196 - 33 57 64 76 78 100 110 361 892 1340 2212 Useful range 271 to -269 -203 to -160 -60 to 100 0 to 120 10 to 130 10 to 160 0 to 130 30 to 200 50 to 200 250 to 650 600 to 1200 1000 to 1800 1800 to 2300 4. Applications Typical applications of heat pipes in mould cooling include (1) In small cores like Ball Pen, Barrel and disposable syringes, normal water cooling becomes very difficult. Cooling channels get blocked either due to rust or impurities in water, causing production problems. Heat pipes are best for such cases. (2) In double wall containers due to thin section of core, normal water-cooling becomes impossible and then one has to continue moulding at very long uneconomical cycles. In such cases heat pipes are suitable to overcome such problems. (3) In case of very old moulds where water cooling is blocked due to moulds rusting or due to some cracks developed on moulds, circulating water through mould becomes impossible. Heat pipes are suitable to overcome the problems. (4) On some products like luggage bags, gating is required to be given from core side, this is done to avoid ISSN : 0975-5462 Vol. 4 No.04 April 2012 1579 Sulas G.Borkar et al. / International Journal of Engineering Science and Technology (IJEST) gate marks on the external face. Ejection system in such moulds is to be provided from the same injection side. Such moulds are known as reverse moulds. These moulds have some problems like gating sink marks, circular flow marks, shining patches around gate etc. heat pipes are used in such cases. (5) Heat pipes are applicable in all normal moulds to enhance the cooling effect. 5. Benefits (1) Cool mould faster and reduce cycle time: The ability of heat pipe to cool moulds is faster and thus reduces cycle time. This occurs due to number of factors, first it permits higher coolant velocity which transfer heat faster, second it transfers heat away from inaccessible area, improving overall cooling rate and reduces cycle time. (2) Improve Part Quality: As the heat pipe transfer heat to the coolent, air or mould component it also dissipates heat evenly along its entire length, this isothermal action provides faster and more uniform cooling .Thus eliminating hot spots which cause sink marks, pulling and spotting. (3) Simplify mould design and lower cost: With heat pipes, Water line design is greatly simplified since coolant flow into the heated area of the mould is not required. In addition the ability to locate heat conductors in areas inaccessible to other cooling devices can further simplify the overall mould design. In most cases the machining and construction time required for the mould is reduced, lowering mould making costs. (4) Reduce maintenance and operating costs: The increased waterline diameter, coolant velocity and heat capacity effectively eliminate scale formation, calcium deposits and the plugging up of small waterlines and ports. In addition, Heat pipes operate in any coolant without corroding. (5) Upgrade existing moulds and dies: Heat pipes effectively solve cooling, cycle time or part quality problems in existing moulds. They can be retrofitted as replacements for bubblers or baffles and to provide heat transfer in previously uncooled areas. 6. Conclusion With the application of heat pipes in conventional water jacket methods in mould cooling, it is found that the various disadvantages associated in conventional water jacket methods in mould cooling are eliminated and the quality of the moulded parts are improved. Further a very high rate of production is achieved. Thus heat pipes are proved to be the most efficient and beneficial tool in mould cooling. 7. References [1] C. G. Li, Yuguang Wu, “Evolutionary optimization of plastic injection mould cooling system layout design” 2010 International Conference on Intelligent system Design and Engineering Application. [2] C. L. Li, C. G. Li, A. C. K. MoK “ Automatic layout design of plastic injection mould cooling system” Computer- Aided Design 37(2005) 645-662. [3] Lubos Behalek, Jozef Dobransky, “Process of cooling injection mould and quality of injection parts” ACTA Technica Corviniensis Bulletin of Engineering. [4] H. Xie and M. Aghazadeh, J. Toth”The Use of Heat Pipes in the Cooling of Portables with High Power Packages”-A Case Study with the Pentium Processor Based Notebooks and Sub –notebooks. [5] Ioan Sauciuc, Masataka Mochizuki, Kouichi Mashiko, Yuji Saito, Thang Nguyen, The Design and Testing of the Super Fiber Heat Pipes for Electronics Cooling Applications” Sixteenth IEEE SEMI-THREMtm Symposium. [6] C K Loh, Enisa Harris and DJ Chou, Comparative Study of Heat Pipes Performances in Different Orientations” 21st IEEE SEMITHERM Symposium. [7] R. S. Khurmi, J. K. Gupta, A Textbook of workshop Technology (Manufacturing Process). [8] S.K. Hajra Choudhury, A. K. Hajra Choudhury, Nirjhar Roy, Elements of Workshop Technology Vol: i Manufacturing Processes [9] A Faghri, Heat pipe Science and Technology, Taylor and Francis, Washington D C, 1995. [10] P D Dunn and D A Reay, Heat Pipes, 4th Edition, Oxford publication, 1994. [11] Brennan, P. J. And Kroliczek, E. J., Heat Pipe Design Handbook, B and K Engineering, 1979. ISSN : 0975-5462 Vol. 4 No.04 April 2012 1580 enfocar la importancia de la producción mediática de los niños en su descubrimiento del mundo, sobre todo utilizando el periódico escolar y la imprenta. Asimismo las asociaciones de profesores trabajaron en esta línea e incluso la enseñanza católica se comprometió desde los años sesenta realizando trabajos originales en el marco de la corriente del Lenguaje Total. Páginas 43-48 45 Comunicar, 28, 2007 En el ámbito de los medios, también desde el principio del siglo XX hay ciertas corrientes de conexión. Pero es a lo largo de los años sesenta cuando se constituyeron asociaciones de periodistas apasionados por sus funciones de mediadores, que fomentaron la importancia ciudadana de los medios como algo cercano a los jóvenes, a los profesores y a las familias. Así se crearon la APIJ (Asociación de Prensa Información para la Juventud), la ARPEJ (Asociación Regional de Prensa y Enseñanza para la Juventud), el CIPE (Comité Interprofesional para la Prensa en la Escuela) o la APE (Asociación de Prensa y Enseñanza), todas ellas para la prensa escrita Estas asociaciones fueron precedidas por movimientos surgidos en mayo de 1968, como el CREPAC que, utilizando películas realizadas por periodistas conocidos, aclaraba temas que habían sido manipulados por una televisión demasiado próxima al poder político y realizaba encuentros con grupos de telespectadores. cipio del siglo XX, y nos han legado textos fundadores muy preciados, importantes trabajos de campo y muchos logros educativos y pedagógicos. La educación en medios ha tenido carácter de oficialidad de múltiples maneras, aunque nunca como una enseñanza global. Así la campaña «Operación Joven Telespectador Activo» (JTA), lanzada al final de los años setenta y financiada de manera interministerial para hacer reflexionar sobre las prácticas televisuales de los jóvenes, la creación del CLEMI (Centro de Educación y Medios de Comunicación) en el seno del Ministerio de Educación Nacional en 1983, la creación de la optativa «Cine-audiovisual» en los bachilleratos de humanidades de los institutos en 1984 (primer bachillerato en 1989) y múltiples referencias a la educación de la imagen, de la prensa, de Internet. La forma más visible y rápida de evaluar el lugar de la educación en medios es valorar el lugar que se le ha reservado en los libros de texto del sistema educa- 2. Construir la educación en los medios sin nombrarla El lugar que ocupa la edu- La denominación «educación en medios», que debería cación en los medios es muy ambiguo, aunque las cosas están cambiando recientemente. entenderse como un concepto integrador que reagrupase todos los medios presentes y futuros, es a menudo percibida En principio, en Francia, co- por los «tradicionalistas de la cultura» como una tendencia mo en muchos otros países, la educación en los medios no es hacia la masificación y la pérdida de la calidad. una disciplina escolar a tiempo completo, sino que se ha ido conformado progresivamente a través de experiencias y reflexiones teóricas que han tivo en Francia. Una inmersión sistemática nos permi- permitido implantar interesantes actividades de carác- te constatar que los textos oficiales acogen numerosos ter puntual. Se ha ganado poco a poco el reconoci- ejemplos, citas, sin delimitarla con precisión. miento de la institución educativa y la comunidad es- colar. Podemos decir que ha conquistado un «lugar», 3. ¿Por qué la escuela ha necesitado casi un siglo en el ámbito de la enseñanza transversal entre las dis- para oficilializar lo que cotidianamente se hacía en ciplinas existentes. ella? Sin embargo, la escuela no está sola en esta aspi- Primero, porque las prácticas de educación en me- ración, porque el trabajo en medios es valorado igual- dios han existido antes de ser nombradas así. Recor- mente por el Ministerio de Cultura (campañas de foto- demos que no fue hasta 1973 cuando aparece este grafía, la llamada «Operación Escuelas», presencia de término y que su definición se debe a los expertos del colegios e institutos en el cine ), así como el Minis- Consejo Internacional del Cine y de la Televisión, que terio de la Juventud y Deportes que ha emprendido en el seno de la UNESCO, definen de esta forma: numerosas iniciativas. «Por educación en medios conviene entender el estu- Así, esta presencia de la educación en los medios dio, la enseñanza, el aprendizaje de los medios moder- no ha sido oficial. ¡La educación de los medios no apa- nos de comunicación y de expresión que forman parte rece oficialmente como tal en los textos de la escuela de un dominio específico y autónomo de conocimien- francesa hasta 2006! tos en la teoría y la práctica pedagógicas, a diferencia Este hecho no nos puede dejar de sorprender ya de su utilización como auxiliar para la enseñanza y el que las experiencias se han multiplicado desde el prin- aprendizaje en otros dominios de conocimientos tales Páginas 43-48 46 Comunicar, 28, 2007 como los de matemáticas, ciencias y geografía». A pe- mente en todas las asignaturas. Incluso los nuevos cu- sar de que esta definición ha servido para otorgarle un rrículos de materias científicas en 2006 para los alum- reconocimiento real, los debates sobre lo que abarca y nos de 11 a 18 años hacen referencia a la necesidad no, no están totalmente extinguidos. de trabajar sobre la información científica y técnica y En segundo lugar, porque si bien a la escuela fran- el uso de las imágenes que nacen de ella. cesa le gusta la innovación, después duda mucho en Desde junio de 2006, aparece oficialmente el tér- reflejar y sancionar estas prácticas innovadoras en sus mino «educación en medios» al publicar el Ministerio textos oficiales. Nos encontramos con una tradición de Educación los nuevos contenidos mínimos y las sólidamente fundada sobre una transmisión de conoci- competencias que deben adquirir los jóvenes al salir mientos muy estructurados, organizados en disciplinas del sistema educativo. escolares que se dedican la mayor parte a transmitir Este documento pretende averiguar cuáles son los conocimientos teóricos. La pedagogía es a menudo se- conocimientos y las competencias indispensables que cundaria, aunque los profesores disfrutan de una ver- deben dominar para terminar con éxito su escolaridad, dadera libertad pedagógica en sus clases. El trabajo seguir su formación y construir su futuro personal y crítico sobre los medios que estaba aún en elaboración profesional. Siete competencias diferentes han sido te- necesitaba este empuje para hacerse oficial. nidas en cuenta y en cada una de ellas, el trabajo con Aunque el trabajo de educación en los medios no los medios es reconocido frecuentemente. Para citar esté reconocido como disciplina, no está ausente de un ejemplo, la competencia sobre el dominio de la len- gua francesa definen las capa- cidades para expresarse oral- La metodología elaborada en el marco de la educación en mente que pueden adquirirse con la utilización de la radio e, medios parece incluso permitir la inclinación de la sociedad incluso, se propone fomentar de la información hacia una sociedad del conocimiento, como defiende la UNESCO. En Francia, se necesitaría unir el interés por la lectura a través de la lectura de la prensa. La educación en los medios las fuerzas dispersas en función de los soportes mediáticos y orientarse más hacia la educación en medios que al dominio adquiere pleno derecho y entidad en la sección sexta titulada «competencias sociales y cívi- técnico de los aparatos. cas» que indica que «los alum- nos deberán ser capaces de juz- gar y tendrán espíritu crítico, lo que supone ser educados en los las programaciones oficiales, ya que, a lo largo de un medios y tener conciencia de su lugar y de su influencia estudio de los textos, los documentalistas del CLEMI en la sociedad». han podido señalar más de una centena de referencias a la educación de los medios en el seno de disciplinas 4. Un entorno positivo como el francés, la historia, la geografía, las lenguas, Si nos atenemos a las cifras, el panorama de la las artes plásticas : trabajos sobre las portadas de educación en medios es muy positivo. Una gran ope- prensa, reflexiones sobre temas mediáticos, análisis de ración de visibilidad como la «Semana de la prensa y publicidad, análisis de imágenes desde todos los ángu- de los medios en la escuela», coordinada por el CLE- los, reflexión sobre las noticias en los países europeos, MI, confirma año tras año, después de 17 convocato- información y opinión rias, el atractivo que ejerce sobre los profesores y los Esta presencia se constata desde la escuela mater- alumnos. Concebida como una gran operación de nal (2 a 6 años) donde, por ejemplo, se le pregunta a complementariedad source of circulating FGF-21. The lack of association between circulating and muscle-expressed FGF-21 also suggests that muscle FGF-21 primarily works in a local manner regulating glucose metabolism in the muscle and/or signals to the adipose tissue in close contact to the muscle. Our study has some limitations. The number of subjects is small and some correlations could have been significant with greater statistical power. Another aspect is that protein levels of FGF-21 were not determined in the muscles extracts, consequently we cannot be sure the increase in FGF-21 mRNA is followed by increased protein expression. In conclusion, we show that FGF-21 mRNA is increased in skeletal muscle in HIV patients and that FGF-21 mRNA in muscle correlates to whole-body (primarily reflecting muscle) insulin resistance. These findings add to the evidence that FGF-21 is a myokine and that muscle FGF-21 might primarily work in an autocrine manner. Acknowledgments We thank the subjects for their participation in this study. Ruth Rousing, Hanne Willumsen, Carsten Nielsen and Flemming Jessen are thanked for excellent technical help. The Danish HIV-Cohort is thanked for providing us HIV-related data. 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