Journal of Information and Computational Science ISSN: 1548-7741

Literature Review on Manufacturing of Bronze Worm with Steel Hub for Cost Reduction.

1Chinjan Patel, 2 Jagdish Pampania, 3 Snehal Trivedi 123 Department of Mechanical Engineering, 1PG student, 2 Assistant Professor 3Head of Department 123 Parul Institute of Technology, Vadodara, Gujarat. [email protected], 2 [email protected]

ABSTRACT

Worm drives are commonly used where large reduction in speed and greater transfer of torque are required within a small space. In order to provide the necessary wear and friction feature in a worm gear, the worm wheel are often made of specific material, mainly bronze. The worm made from hard material (cast iron, cast steel, carbon steel etc.) and the worm gear is from relatively soft material (brass, bronze, aluminium, copper etc.) which causes the wearing or failure of worm gear teeth rapidly because of the sliding contact during operation. The cost of the worm wheel should be reduced by made from multi-material worm gear. The teeth which are in contact with worm is made from brass or bronze as it is and the inner part substitute by non-ferrous material instead of replacing whole gear made from bronze or brass to save cost. The toothed rim part can replace number of times and the inner part remain as it is so the cost of replacing whole gear is reduce.

KEYWORDS: Compound casting, Worm wheel, Multi-material gear, Cost reduction.

1. Introduction

The worm and worm gear are used to power device in which a worm meshes with a worm gear to transmit power between two non-intersecting shafts that are oriented at a right angle. commonly used where large reduction in speed and greater transfer of torque are required within a small space. It is used in lifts/elevators, conveyors, automobile industries, marine industries etc. The coast of the worm drive is higher than other because of the worm gear made from bronze. The amount stress acting on the worm wheel consider to worm is much more but due to lubrication and baring properties of the bronze the worm gear made from bronze material.

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Material and properties for worm gear: The steels used for worms are normalized carbon steels (40C8 and 55C8), case- hardened carbon steels (10C4 and 14C6), case-hardened alloy steels (16Ni80Cr60 and 20Ni2Mo25), and nickel-chromium steels (13Ni3Cr80 and 15Ni4Cr1). The case-hardened steels are typically with a surface hardness of 60 HRC. The commonly used worm gear bronzes are tin bronzes, manganese bronzes, aluminium bronzes, and silicon bronzes [12]. Cast or wrought manganese bronzes are the toughest materials in the bronze family, with good wear resistance, but do not possess the same degree of corrosion resistance, wear ability, or bearing quality as the tin bronzes or aluminium bronzes. Aluminium bronzes are similar to the manganese bronzes in toughness, but are lighter in weight. They are available in both cast and wrought forms and can be heat treated to attain higher mechanical properties. Their bearing quality is better than manganese bronzes but inferior to tin bronzes. The stress acting on worm wheel is different at different places. The higher stress acting at on line of contact at teeth, roots of teeth and key way. Due to higher stress the teeth are break rapidly and it required to changing of the whole gear made from bronze. It increase the cost of the using of worm gear.

Fig 1: Failure of teeth of Worm gear The most common gear failures that occur in worm gearbox are wear, pitting, scoring and fracture. 1. Wear is a surface phenomenon in which material of gear is removed from the surface of teeth of gear due to contact with other gear. It includes Polishing, Moderate and Excessive Wear, Abrasive Wear and Corrosive Wear. The main reason for wear is insufficient lubrication, rough running etc. 2. Pitting is surface fatigue failure which occurs when endurance limit of material is exceeded due to large contact stress and large no of stress cycle. It includes initial pitting, Destructive pitting and Spalling. The main cause of pitting is high contact stress, overload etc.

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3. Scoring is rapid wear resulting due to failure of oil film due to overheating of mesh due to which metal to metal contact takes place producing alternative welding and tearing which remove material from teeth surface more rapidly. It include Moderate and destructive scoring which is caused due to inadequate lubrication, excessive operating temperature, excessive surface load and surface speed. To avoid scoring good lubrication system should be provided.

Bond

Fig 2: Multi-material Gear This problem can be solved by manufacturing of multi-material worm gear. The cost can be reduce by substituting the inner part of the worm gear. The aluminium bronze is used for teeth rim and the steel is used inner part to reduce the cost of the worm gear. The aluminium bronze have higher mechanical properties and corrosion resistance [10].

No. Types of Bronze Properties 1. Aluminum Bronze Al 6%-12%, Iron 6%, Ni 6%. High strength, wear resistance and corrosion resistance. 2. Phosphorus Bronze Tin content – 0.5% to 11.0%, phosphorous content - 0.01% to 0.35%. Tin increase resistance and tensile strength, Phosphorous increase wear resistance and stiffness. 3. Nickel Bronze 62%-70% copper, 20%-24.5% zinc, and 5.5%- 15% nickel. Not strong than other type. It have properties like electric resistance, ductility, malleability, non- magnetic and it is corrosion resistance. 4. Silicon Bronze They contain 20% zinc and 6% silicon. It is a high-strength alloy, with an easy pouring ability,

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high mechanical, resilient, and anti-friction properties, resistant to corrosion and wear- resistant. 5. Manganese Bronze Manganese bronze is made of up to 3% manganese, copper, zinc, aluminum, and iron. It is shock-resistant and deforms instead of breaking. It is highly resistant to saltwater corrosion and is therefore often used in boat propellers. Table 1. Types of Bronzes

2. Literature Review

A.S.S.A. Masoud et al.[1] researched to increase the durability of by using multi-material. The most of the gear body is made from the low tensile strength material (aluminium) and the only portion which have to withstand with high tensile is made from the high tensile strength material (steel). The diffusion bonding between the steel and aluminium is strong enough to withstand the maximum shear stress and which reduce the deflection of the teeth of the gear up to16%. Fatih karpat et al.[2] use the combination of the steel and the aluminium to reduce the weight of the gear and the analysis the stress act on the root region of the gear by using different size of the rim. The steel is use for high stress region and the core is of aluminium. Increment in the steel rim cause increase in the weight of the gear and reduce the stress and stiffness at the root region of the gear. William H Miller et al.[3] manufactured a gear by using centrifugal casting of bronze as outer rim and yellow brass as inner annular to reduce the cost of the gear. The tensile strength of outer rim bronze is 50,525 psi and the tensile strength of metallurgical bond is 55,500 psi which is more than bronze. So, it is safe to use of the manufactured gear. All the other defects such as voids, cracks, slag etc. are very less due to centrifugal casting method. Denis J Politis et al.[4] perform FE analysis during operation on single material gear as well as for the bi-metallic gear in which steel is used at the outer material and the aluminium is for the core material. It shows that the stress acting 1mm below the line of contact is reduced about 80% in single material gear. In bi-metallic gear when the size of the band of steel is more (about 4mm to 6 mm) the stress acted on the core is same as stress acted on single material. Stress acted on core below 2mm is almost half of the stress acted at stress at line of contact which is less than the yield strength of the aluminium. Jianguo lin et al.[5] used forming method to manufacturing of multi-material gear. In which teeth of the gear and the key-way which have to withstand high stresses made from high performance material and the core made from low performance

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material as they stress below the depth of teeth is reduced about 50%. All the pre- formed elements are heated up to the forming temperature and using die shape is given.in this method the micro structure of the product should be refined and the strength of material increased. There is mechanical bond between the elements. Michal Vorel et al.[6] joining of the two dissimilar material by electrobeam welding to get worm gear. The welding between the bronze rim and steel hub cause cracks, notches and the overlapping problem due to weld reaches up to only 66% of the weld width. The crack problem also shown if the weld reaches 100% because e crack after the welding process. Kaushal Kishore et al.[7] researched that the 40% of the failure of teeth cause from the intergranual brittle fracture result shown through scanning electron microscopy. The failure cause from more content of nickel and the uncountable process of casting. The large number of voids and cracks are form due to content of nickel which reduce the strength of the gear. The amount of nickel should be always kept below the 0.5% wt. Yuanyuan Li et al.[8] studied the tribology behaviour of the aluminium bronze to improve the mechanical properties. The addition of anti-friction component Pb and by controlling the solidification process the microstructure can be improved as well as the wear and the friction properties also can be improved. Albert S. Wadleigh et al.[9] manufacture the composite gear and shaft as the in gear and shaft some part have to withstand higher stress like splines, teeth and bearing races and the other part like gear web and gear shaft have service at lower stress. In composite gear teeth made from steel and the web are from titanium. First the element brought in to forming temperature and with the help of force the bond is created and in shaft the upper annular made from steel and the inner annular made from aluminium to reduce weight. Kavin Jr et al [10] found the addition of the nickel and the degassing agent in the aluminium bronze increase the hardness and the strength of material. Addition of the degasing agent reduce the dissolve gases and accelerate the solidification time stage. Tensile and micro hardness directly affected by solidification time. Bothe are increase tensile strength and micro hardness as the cooling of microstructure create new nucleation which affect these properties due to degassing agents. Small amount of nickel increase the mechanical and corrosion resistance properties of aluminium bronze.

3. Summary

To manufacturing of Aluminium bronze worm gear with steel hub there are several methods are available such as forming, compound casting, sand casting, centrifugal casting, electron beam welding etc. The other procedure are nut and bolting, threading, riveting [6]. In forming method the both metal brought in to the forming temperature then through by force the two metal are by diffusion of material make metallurgical bond. Centrifugal casting provide sound casting and the high strength

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bonding due to less slag involve. Riveting, threading, nut and bolt is usually use for large worm gear size. Compound casting is the process in which two metallic materials, i.e. one in the solid state and the other as a liquid, are brought into contact with each other in such a manner that a diffusion reaction zone forms between the two materials and thus a continuous metallic transition occurs from one metal to the other. Compound casting might, for example, be deployed to join a wrought alloy part with cast components of complex shape simply by casting a liquid metal onto or around the solid component. A bimetal composite fabricated by compound casting have mechanical joint. The joining of dissimilar metal with electron beam welding is not suitable as the weld bead reach only 66% which make cavities in bond and increase the chances of failure.

4. Research Gap The literature are too focused on the multi material gear manufacturing but the strength of the bond between the two different materials is major problem in case of high performance application. The stress acting on the bond is torsional shear stress during operation. It is important factor which affect the failure during working condition of gear.

5. Conclusion The cost of the changing only rim is very less compared to changing the whole bronze gear. Aluminium bronze have good wear and friction properties than phosphorus and tin bronze. Aluminium bronze used as a bronze rim and any other ferrous material as per requirement van be used for hub.  The strength can be increase by rapid solidification of the aluminium bronze material.  Aluminium bronze have good frictional as well as bearing properties. The solidification rate of casting aluminium bronze is higher and the increase in the strength while cooling in air.  Addition of the nickel and degassing agent improve the casting and bonding strength. Strength and hardness of the Aluminium bronze rim increase in case of casting method.  By using threading, not and bolting, rivets with metallurgical bond one can increase the strength of the bond.

6. REFERENCES

[1] A.S.S.A. Masoud and M. Qasim, Increasing spur gear durability: two-material spur gear, Mechanical Engineering Department, Jordan University of Science

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and Technology, P.O. Box 3030, Irbid, Jordan, Int. J. Computer Applications in Technology, Vol. 24, No. 3, 2005. [2] Fatih Karpat, , Tufan Gürkan Yılmaz, Oğuz Doğan, Onur Can Kalay, Stress and Mess Stiffness Evaluation of immaterial Spur Gear, Department of mechanical engineering, Bursa Uludag University, Bursa Turkey, Proceedings of the ASME 2019 International Mechanical Engineering Congress and Exposition IMECE2019 November 11-14, 2019, Salt Lake City, UT, USA. [3] William H. Miller, Valleyview Rd., Pittsburgh, Gear Blank, United States Patent no. 3,847,557, November 12, 1974. [4] D. J. Politisa, J. Lina,*, T. A. Deanb, D. S. Balinta, An Investigation into the Forging of Bi-metal , Department of Mechanical Engineering, Imperial College London, Exhibition Road South Kensington, London SW7 2AZ, UK, Journal of Materials Processing Technology, 2014.04.20 [5] Jianguo Lin, Denis Politis, Trevor Anthony Dean, West Midlands; Daniel Balint, Method Of Manufacturing Multi Material Gears, United States, Patent Application Publication, Pub. No.: US 2014/029894.0 A1, Pub. Date: Oct. 9, 2014 [6] Michal Vorel, Erhard Leidich, Advanced Design Of Worm Wheels Made Of Dissimilar Materials, Proceedings of IMECE’03 E International Mechanical Engineering Congress Washington, D.C., November 15–21, 2003. [7] Kaushal Kishore . Goutam Mukhopadhyay . Manashi Adhikary, Metallurgical Analysis of Premature Failure of a Phosphor Bronze Worm Wheel, 15 August 2018 ASM International 2018. [8] Yuanyuan Li, Tungwai Leo Ngai, Wei Xia, Mechanical, friction and wear behaviors of a novel high-strength wear-resisting aluminum bronze, ELSEVIER, 27 November 1995. [9] Albert S. Wadleigh, MULTI-METAL COMPOSITE GEAR/SHAFT, United States Patent, Patent Number: 5,271,287, Dec. 21, 1993 [10] Aluminium Bronze Alloys for Industry, CDA, publication no.83, March 1986 [11] Kavinjr, Rashidi M. M and Ahmad A. H, Investigation of nickel aluminium bronze castings properties by degassing agent technique, 1st International Postgraduate Conference on Mechanical Engineering, IOP Publishing , (IPCME2018) [12] Joe J. Liou and Stefan Rakuff, The Development of Worm Drives, Power Transmission Enginnering, Feb 2018.

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