Int. Journal of Applied Sciences and Engineering Research, Vol. 3, Issue 5, 2014
© 2014 by the authors – Licensee IJASER- Under Creative Commons License 3.0
Research article
www.ijaser.com
[email protected]
ISSN 2277 – 9442
Development of large diameter v-belt pulley using coreless drag
and wire-reinforced cheek
Okechukwu, Chijioke1, Dauda, Mohammed1, Dahunsi, Olurotimi Akintunde2, Oke, Peter Kayode2
1Advanced Manufacturing Technology Programme, P.M.B. 1174, Jalingo, Taraba State, Nigeria.
2Department of Mechanical Engineering, Federal University of Technology, P.M.B. 704, Akure, Ondo
State, Nigeria.
DOI: 10.6088/ijaser.030500011
Abstract: Turning of metal pulleys in lathe machines is preceded by casting of the blanks. As the diameter
of the pulley increases, this method becomes more challenging due to the difficulty of taper turning
grooves on the blank. Cores are used to make cavities in such pulleys to reduce their weights. The
processes involved in making cores add to the cost of producing such parts. This project is aimed at
reducing the machining and moulding steps and costs when producing large diameter pulleys. A wooden
split pattern was moulded in a wire-reinforced cheek, then; the drag was positioned on the cheek, followed
by filling of holes in the pattern with facing sand, pouring and ramming of the moulding sand in the drag;
thereafter, the drag-cheek subassembly was turned upside down and the cope positioned on the cheek,
filled with moulding sand and rammed. The pattern was withdrawn from the cheek by removing the
bottom-half-rim, followed by the cheek and lastly the top-half-rim from the drag. Part modeling of the
pattern and moulding stages was done in Pro/Engineer software. The cast pulley was made of aluminium
and showed minimal deviation from dimensional specifications.
Key words: Pulley, split pattern, coreless drag, reinforced cheek, casting, taper turning, cost reduction.
1. Introduction
Work study as a technique for increasing productivity demands that unnecessary movement during
production should be eliminated. Efficient and economical utilization of input resources, elimination of all
types of wastages and good product design by simplification and standardisation have been identified as
techniques for improving productivity (Sharma, 2006). It can be said that “simplification of the process
steps and reduction of the input resources will increase productivity at the same or more output”. The
production of v-belt pulleys has been achieved using: two-box moulding with a false cheek (Otu, 2008);
groove forming roller for the production of multi-stage pulleys (Bytzek, 1981; Shohara et al., 2002);
assembling of separate parts (Bhatt and Panchal, 2009); metal blank forging (Gobeille, 1973); and
segmented pattern in a three flask mould (Dauda and Okechukwu, 2013). Of specific interest is the
production of large diameter v-belt pulleys; these parts impose the challenge of demanding a special lathe
for their accommodation. The machining of such parts requires that the distance between the headstock
centre and the bed is more than the radius of the part and the gap between the tool post and the edge of the
blank can contain the parallel or taper turning tools. There are few lathe machines in Nigeria that can
accommodate and turn 500mm diameter pulley blanks. A few lathes can hold such size for drilling
operation, but the tool post restriction makes it difficult to carry out turning operations. There is no
gainsaying that the taper turning of v-belt pulleys consumes time and energy, which add to the cost of
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*Corresponding author (e-mail: [email protected])
Received on October 2014; Published on October 2014
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Development of large diameter v-belt pulley using coreless drag and wire-reinforced cheek
producing such parts.
The importance of pulleys in machineries cannot be overemphasized as these machine elements are used in
conveyors, elevators, block and tackle, wells, cranes, flag poles, cars etc. Pulleys are used to transmit
power from one shaft to another by means of flat belts, v-belts or ropes. They may be made of cast iron,
cast steel, pressed steel, wood and paper (Khurmi and Gupta, 2005). Some applications of pulleys require
light weight; this is usually achieved with light metals such as aluminium alloys or more often the
introduction of cores in the mould before casting. The core has been defined as “the portion of mould
which forms the hollow interior of casting or hole through the casting” (Fiore and Zanetti, 2007). The core
material used in sand casting operation is primarily sand mixed with binders (Abdulwahab et al., 2008).
Core making involves coating a refractory aggregate with binder, compacting the coated sand into the
desired shape (in a core box), and curing (hardening) the compacted mass for easy handling (Wile et al.,
1962). Core box pattern equipment, baking equipment and handling facilities are required for making cores
(Jain, 2009). Processes such as sand mixing, compaction, coating, curing and venting, and such materials
as release agents, binders used in coremaking contribute to the production cost and take reasonable
production time. The cost can be acceptable if the price of the product is high enough to cushion the effect
of the core cost. Regarding the production of large diameter v-belt pulleys this cost can be eliminated using
the technique presented herein.
The objectives of this project include: (a) Reduction of the cost of machining large diameter v-belt pulleys
by eliminating the taper turning operation; (b) Reduction of the cost of casting hollow pulley blanks by
eliminating the cost of core making; (c) Provision of a method of producing large diameter grooved pulleys
to ease the achievement of higher or lower velocity ratios in machineries.
2. Materials and methods
2.1 Materials
The materials used in making the large diameter v-belt pulley pattern, moulding boxes, sand moulding, and
casting are listed in table1 below.
Table1: List of materials used in producing large diameter pulley pattern, making sand moulds and casting
S/N
Materials
Uses
1
Obeche wood
Used in making drag, cheek and cope boxes
2
Plywood
Used in making split pulley pattern
3
Binding wire
Reinforcing the cheek
4
Nails
Joining moulding boxes’ parts and suspending the
reinforcing wire round the interior parts of the cheek
5
Abrasive papers (rough
and smooth)
Sanding the split pulley parts
6
Top bond glue
Bonding pattern parts to form the top and bottom half rims
7
Mixture of hardener and
auto-body filler
Used to achieve the slanted parts of the split pulley pattern
8
Silica sand
Used as facing sand
Okechukwu, Chijioke et al.,
Int. Journal of Applied Sciences and Engineering Research, Vol. 3, Issue 5, 2014
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Development of large diameter v-belt pulley using coreless drag and wire-reinforced cheek
9
Mixture of river bank
sand, bentonite and
water
Used as backing sand
10
Aluminium return scrap
Used in producing the cast pulley
11
Charcoal
Used as fuel for firing
Tools and equipment used include: Hammer, pliers, measuring tape, pencil, spoon, shovel, rammers, flat
bar, trowel, vernier caliper, jigsaw, 2400W angle grinder, and 600W hand drilling machine.
2.2 Part modeling and making of the large diameter v-belt pulley pattern
The drawing of the pulley was done in Pro/Engineer software before the making of the split pattern with
plywood. The three parts of a belt pulley have been identified as – hub or boss, arms and rim (Bhatt and
Panchal, 2009). These parts are shown in figure 1. The method of improvising the pulley pattern has been
described in the production of the v-belt pulley using segmented pattern (Dauda and Okechukwu, 2013).
Different views of the split pulley pattern are shown below.
Figure 1: Exploded view of the pulley pattern
Figure 2: Third angle orthographic projection
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Development of large diameter v-belt pulley using coreless drag and wire-reinforced cheek
Figure 3: Isometric view of the pulley pattern
Figure 4: Picture of the pulley pattern
Note: All dimensions are in mm.
2.3 Description of sand moulding stages
The pattern, being a positive replica of the part to be produced was embedded in the mould to create the
pulley cavity when removed. Figures 5 to 14 show the sand moulding sequence leading to the creation of
the pattern cavity in the mould.
Figure 5: Place the reinforced cheek on the moulding board and position the pulley pattern at the centre of
the cheek
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Development of large diameter v-belt pulley using coreless drag and wire-reinforced cheek
Figure 6: Pour and ram the facing sand round the circumference of the pulley pattern
Figure 7: Place the drag on the cheek, fill the holes in the pattern with facing sand, pour and
sand, and flatten the surface of the drag
ram backing
Figure 8: Turn the cheek-drag-subassembly upside down
Figure 9: Position the sprue pipe at the centre of the pattern surface, place the cope on the cheek, pour and
ram facing and backing sands, then, create a basin around the sprue
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Development of large diameter v-belt pulley using coreless drag and wire-reinforced cheek
Figure 10: Vent the cope, remove the sprue pipe and the cope
Figure 11: Rap and withdraw the bottom-half-rim of the pattern
Figure 12: Remove the cheek, rap and withdraw the top-half-rim of the pattern from the drag
Figure 13: Place the cheek on the drag
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Development of large diameter v-belt pulley using coreless drag and wire-reinforced cheek
Figure 14: Place the cope on the cheek, allow the mould to dry for about two days depending on the
moisture content of the moulding sand; then, the mould is ready for casting
Figure 15: Third angle projection of the mould assembly
Figure 16: Picture of the pattern impression in the drag, cheek and cope
Note: All dimensions are in mm.
3. Results and discussion
3.1 Results
Melting of aluminium returns was carried out in an improvised charcoal furnace. Prior to charging these
returns, the mass properties of the cast pulley were determined with the Pro/Engineer software using
density of aluminium as 0.0000000027tonne/m3. The result of the analysis is as follows:
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Development of large diameter v-belt pulley using coreless drag and wire-reinforced cheek
VOLUME = 2.0904828e+06 MM^3
SURFACE AREA = 4.5072226e+05 MM^2
AVERAGE DENSITY = 2.7000000e-09 TONNE / MM^3
MASS = 5.6443036e-03 TONNE
Figure 17: Pictures of the cast pulley after casting and fettling
Neglecting shrinkage, this implies that the mass of the pulley when it is made of aluminium is 5.64kg.
Hence, about 10kg of aluminium was melted in the charcoal furnace, considering the quantity that will go
into the sprue and slag. However, after casting, solidification, cooling and fettling, the mass of the cast
pulley was found to be 5.10kg.
3.2 Discussion
Inspection of the parts of the cast pulley after fettling revealed that the hub base diameter was 119mm
instead of 120mm, and the thickness of the top-half-rim dropped from 5mm to 4.5mm. These dimensional
differences are the cause of the deviation in mass. The cavities in the pulley took the shape of the sand
protrusions on the drag; hence, these protrusions did the core function satisfactorily.
4. Conclusions and recommendations
4.1 Conclusions
Reinforcement of the cheek with binding wire and nails prevented the collapsing of the sand in the cheek
during and after pattern removal. Pouring of the liquid aluminium through a centered top gate ensured
uniform distribution of the metal round the pulley cavity. Placing of a heavy engine cylinder top on the
cope before casting countered the metallostatic pressure of the metal and prevented mound expansion.
Previous trial moulding with cores showed that the core making not only consumes material resources but
also takes a lot of production time, thereby making the coreless drag method cheaper and less time
consuming. Lateral splitting of the pattern through the groove paved way for easy withdrawal from the
mould. Finishing the pulley produced using the method described herein in a lathe machine will ensure that
the pulley is concentric, eliminate taper turning operation, reduce the machining steps to facing and drilling.
These will in no small measure reduce the time, energy, and cost expenditures. Machine designers can
explore this method to achieve very high or low speed ratios in machineries.
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Development of large diameter v-belt pulley using coreless drag and wire-reinforced cheek
4.2 Recommendations
Problems encountered in the course of the trial moulding showed that the following suggestions should be
adhered to when producing large diameter pulley by casting:
Sand moulding should be done where the drag will not be moved after pattern withdrawal as the
sand protrusion on the drag or positioning of cores in the drag can lead to the collapsing of the
moulding sand in the drag. This may be prevented by reinforcing the drag with binding wire.
Risers can be used to minimize shrinkage; however, their positions should be at points that are not
close to the groove edges e.g. hub base and arms.
5. References
1. Abdulwahab, M., Gaminana, J. O., Bellow, K. A., and Achuokpa, E. O. (2008). Prospects of local
core binders in foundry industries. Proceedings of Nigerian Metallurgical Society. 25th Annual
Conference, Akure, pp 210-213.
2. Bhatt, N. D. and Panchal V. M. (2009). Machine drawing. Gujarat: Charotar Publishing House Pvt.
Ltd.
3. Bytzek, K. K. (1981). Method of pulley manufacture and product. U. S. Patent No. 4,273,547.
4. Dauda, M. and Okechukwu, C. (2013). Production of v-belt pulley using segmented pattern. The
International Journal of Engineering and Science, Vol. 2, Issue 8, pp 01-07.
5. Fiore, S. and Zanetti, M. C. (2007). Foundry waste reuse and recycling in concrete production.
American Journal of Environmental Science, Vol. 3, Issue 3, pp 135-142.
6. Gobeille, W. P. (1973). Composite V-belt pulley and method. U. S. Patent No. 3,772,928.
7. Jain, R. K. (2009). Production technology. 17th Edition, New Delhi: Khanna Publishers.
8. Khurmi, R. S. and Gupta, J. K. (2005). A textbook of machine design. New Delhi: Eurasia
Publishing (Pvt,) Ltd.
9. Otu, A. E. (2008). Moulding and casting of a grooved pulley using green sand technique. A thesis
submitted to the Department of Mechanical Engineering, Federal University of Technology,
Minna, Niger State, and Nigeria.
10. Sharma, P. C. (2006). A textbook of production engineering. New Delhi: S. Chand and Company
Ltd.
11. Shohara, H., Adachi, M., Suzuki, H., Kasuya, Y., Ohno, T., Tabuchi, Y. and Kinoshita M. (2002).
Multi-stage pulley and production method thereof. U. S. Patent No. 6,463,659B2.
12. Wile, L. E., Strausbaugh, K., Archibald, J. J., Smith, R. L., and Piwonska, T. S. (1962).
Coremaking. Molding Methods and Materials, American Foundrymen’s Society.
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