Title of Invention

NOVEL COMPOSITE CRANKSHAFT AND A METHOD OF MANUFACTURING THE SAME

Abstract

The present invention relates to a novel composite crankshaft and a process of manufacturing the same comprising the web component fabricated through Powder Metallurgy Technology by way of sintering and compacting in the die at a specific temperature range; annealing and sizing the compact material to meet the predetermined final dimensions.; bonding the shaft component made of wrought iron to the web.

Full Text

NOVEL COMPOSITE CRANKSHAFT AND A PROCESS OF MANUFACTURING THE SAME FIELD OF INVENTION: The present invention relates to a novel composite crankshaft for automobile parts and a process of manufacturing the same. Particularly, the present invention relates to novel crankshafts for 2 wheelers such as motorbikes, scooters and mopeds. BACKGROUND OF INVENTION: Crankshaft is a component that converts the reciprocating motion of the piston/connecting rod into rotating motion thereby transmitting power generated from the cylinder-piston assembly. The said crankshaft consists of two parts namely a web and a shaft. The shaft being in contact with bearings is induction hardened. The web portion of the crankshaft is connected to the connecting rod through the crank pin. PRIOR ART REFERENCES: Conventional technology for production of crankshaft is hot forging of medium carbon steel followed by extensive machining to achieve the final dimensions. Subsequently the shaft portion is induction hardened. The mass, moment of inertia and the center of gravity of the web are crucial for efficient power transfer. The prior art crankshafts are costly and cumbersome to manufacture. OBJECTS OF INVENTION: The main object of the invention is to provide a composite crankshaft with the web portion fabricated through Powder Metallurgy Technology joined to a wrought shaft. Another object of the invention relates to a process of producing a crankshaft wherein the web portion is produced by Powder Metallurgy route and joined with a shaft made out of wrought steel. Further, another object of the invention provides for a web portion, that is constructed in such a way the product of mass and distance of center of gravity (C.G) from crank pin hole as well as the moment of inertia about the central axis is same as that of conventional crankshaft. Another object of the invention is to provide a novel web suitable for Powder Metallurgy route wherein the mass; moment of inertia and C.G requirements are met. Yet another object of the invention is to provide a novel bonding technique between the shaft and the web wherein the crankshaft is able to withstand the torque generated. SUMMARY OF THE INVENTION: To meet the above objective and others, the present invention provides a novel composite crankshaft in which the web portion is made of powdered metals, that is joined to a wrought shaft, and a process of manufacturing said composite crankshaft. DESCRIPTION OF THE INVENTION: Accordingly, the present invention provides a crankshaft for use in automobiles, particularly two-wheelers, comprising a web produced by Powder Metallurgy Technology and a shaft of wrought material obtained by machining. An embodiment of the present invention, wherein the web component is made of Fe and other essential/optional elements Hke C, P, S, Mn, Cr, Ni, Cu, Mo, Pb in the range of 0-20%, Yet another embodiment of the present invention, wherein the web component comprises 0.8% Zn Stearate as lubricant. Still, yet another embodiment of the present invention, wherein the density of the web component is in the range of 6.7-8 g/cc. Further, yet another embodiment of the present invention, wherein the web and shaft components are bonded optimally to withstand the torque generated. Another embodiment of the present invention provides for a process of manufacturing crankshaft, said process comprising; (i) providing a suitable die and filling the die with alloy powder material comprising Fe and compacting the material under a pressure range of 4-8 tons/cm2; (ii) sintering the compacted material at 1050-1280oC for a period of 10 - 60 min; (iii) sintering the web to meet the predetermined dimensional accuracy; (iv) infiltrating the web completely or partially to meet the C.G and mass, moment of inertia requirements; (v) selective sizing of the web component in order to meet the C.G and mass requirements; (vi) presintering the compact material is at a temperature 800 - 950oC; (vii) coining and further sintering web sintered at temperature between 1050oC - 1250oC; (viii) annealng and sizing the same to meet the final dimensions; and (ix) bonding the web made of powder metal alloys with a shaft of wrought iron. Yet another embodiment of the present invention, wherein bonding the shaft to the web is by press fitting which comprises fitting the shaft through a hole in the web whose diameter is slightly smaller than that of the shaft or vice-versa, where the web-shaft assembly will be held in place by the compressive forces generated by the press fitting. Further, yet another embodiment of the present invention, wherein key and key way are provided on the shaft and the web respectively, that provide a mechanical locking in addition to the compressive stresses. Still, yet another embodiment of the present invention, wherein the contact surfaces are knurled for press fitting as the knurling provides additional friction resistance to slipping. Yet another embodiment of the present invention, wherein a process of shrink fit that comprises sudden cooling of the shaft to subzero temperatures resulting in thermal contraction. In yet another embodiment of the present invention, the thermally contracted shaft is shrink-fitted through the hole and it expands to fill the hole on reaching room temperature, thus holding the web-shaft assembly in place. Still in yet another embodiment of the present invention, brazing is done to bond the web with shaft through a lower melting metal or alloy. Further, in yet another embodiment of the present invention, sinter bonding of the web is done with the shaft by way of sinter brazing compound selected from a copper based alloy. ... Accordingly the present invention provides a novel composite crankshaft for two-wheelers, comprising a web component made of powder metal alloys and a shaft of wrought iron, wherein the web and shaft components are bonded optimally to withstand the torque generated. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS: Figure 1 shows Conventional Web Figure 2 shows Powder Metallurgy web Figure 3 shows Wrought Shaft Figure 4 shows Novel Crankshaft Fig.l shows the conventional web made out of wrought steel. This web is made of wrought steel by hot forging of medium carbon steel followed by extensive machining. Fig.2 shows the Powder Metallurgy web( ) i.e., the web made by conventional powder metallic technique, wherein web component is made of Fe and other alloys and sintering at high temperatures, followed by a process of infiltration to meet the Centre of Gravity requirements. Fig.3 shows wrought shaft. Fig 4 shows connection of Powder Metallurgy web (1) with a wrought shaft (2) by a novel bonding method. The Powder Metallurgy web is of a lower density as compared to the shaft. As opposed to the conventional crankshaft, the present crankshaft is produced with less machining, greater weight control and at a lesser cost. ADVANTAGES One of the main advantages of this novel invention is that less machining is involved during the said process. Yet another advantage of the Composite Crankshaft is that it has an improved weight control over the hot forged crankshaft. The cost of the Composite Crankshaft is lower than the conventional hot forged crankshaft. We Claim: 1. A novel composite crankshaft for two-wheelers, comprising a web component made of powder metal alloys and a shaft of wrought iron, wherein the web and shaft components are bonded optimally to withstand the torque generated. 2. A device as claimed in claim 1, wherein the web component is made of Fe and other essential/optional alloy elements like C, P, S, Mn, Cr, Ni, Cu, Mo, Pb upto the range of 20%. 3. A device as claimed in claim 1, wherein the web component comprising .8% Zn Stearate as lubricant. 4. A device as claimed in claim 1, wherein the density of the web component is in the range of 6.7-8 g/cc. 5. A device as claimed in claim 1, wherein the web and shaft components are bonded by press fitting. 6. A device as claimed in claim 1, wherein a key on the shaft and a key hole on the web are optionally provided for mechanical locking between them. 7. A process of manufacturing the crankshaft claimed in claim l, wherein the said process comprising; (i) providing a suitable die and filling the die with alloy powder material comprising Fe and compacting the material under a pressure range of 4-8 tons/cm ; (ii) sintering the compacted material at 1050-1280°C for a period of 15-45 minutes; (iii) sintering the web to meet the predetermined dimensional accuracy; (iv) infiltrating the web completely or partially to meet the Centre of Gravity and mass, moment of inertia requirements; (v) selective sizing of the web component in order to meet the Centre of Gravity and mass requirements; (vi) presintering the compact material at a temperature 800 - 950oC; (vii) coining for increasing the density and further sintering the web sintered at temperature between 1050oC-1250°C for providing metallurgical bonding; (viii) annealing and sizing the same to meet the final dimensions; and (ix) bonding the web made of powder metal alloys with a shaft of wrought iron. 7. A process as claimed in claim 6, wherein the bonding of the shaft with the web is by press fitting which comprises ; (a) fitting the shaft through a hole in the web whose diameter is slightly smaller than that of the shaft or vice-versa; and (b) holding the web-shaft assembly in place by the compressive forces generated as result of press fitting 8. A process as claimed in claimed in claim 6, wherein providing a key and a key-way on the shaft and the web respectively, for mechanical locking in addition to the compressive stresses. 9. A process as claimed in claim 6, wherein knurling the contact surfaces for press fitting to provide an additional friction resistance to slipping. 10. A process as claimed in claim 8, wherein the mechanical locking is achieved by shrink fitting. 11. A process as claimed in claim 10, wherein shrink fitting comprising; (a) sudden cooling of the shaft to sub-zero temperatures resulting in thermal contraction; (b) shrink-fitting the thermally contracted shaft through the hole; and (c) holding the web-shaft assembly in place as shrink-fitted shaft expands to fill the hole on reaching room temperature 12. A process as claimed in claim 10, wherein brazing is done to bond the web with shaft through a lower melting metal or alloy. 13. A process as claimed in claim 11, wherein sinter bonding the web with the shaft with help of sinter brazing compound selected from a copper based alloy. 14. A novel composite crank shaft for two wheelers substantially as herein described with reference to the accompanying drawings. 15. A process of manufacturing crank shaft substantially as herein described with reference to the examples and accompanying drawings.

Documents:

540-mas-2000-abstract.pdf

540-mas-2000-claims filed.pdf

540-mas-2000-claims granted.pdf

540-mas-2000-correspondnece-others.pdf

540-mas-2000-correspondnece-po.pdf

540-mas-2000-description(complete) filed.pdf

540-mas-2000-description(complete) granted.pdf

540-mas-2000-description(provisional).pdf

540-mas-2000-drawings.pdf

540-mas-2000-form 1.pdf

540-mas-2000-form 26.pdf

540-mas-2000-form 3.pdf

540-mas-2000-form 5.pdf

540-mas-2000-other documents.pdf