DESC:TECHNICAL FIELD OF THE INVENTION
The present disclosure relates to a process for surface-finishing for gears and more particularly for hypoid gears.
BACKGROUND OF THE INVENTION
Hypoid gears are a type of spiral bevel gear that are used to transmit rotational power between two shafts at right angles. Hypoid gears are generally used in automotive transmissions to avoid intersection of the axis of the pinion with the the axis of the gear. The geaometry of teeth on the pinion is spiral and the teeth on the gear are cut nonradially.
As there is constant interaction between pinion and gear, the noise, vibration and harshness (NVH) are the important criterias. In current state of art, the NVH is on higher side that may lead to wear and friction resulting in the drive train losses. The continuous friction and wear affects the durability of the gear.
Accordingly, there is a need of surface-finishing for the hypoid gears to eliminate above mentioned drawbacks.
SUMMARY OF THE INVENTION
The present invention provides a process for surface-finishing of the gears comprising the steps of Manganese phosphating the gear; vibro-finishing the Manganese phosphated gear; hot rinsing the gear; coating the gear with the rust proofing oil; and drying the coated gear by hot air thereby providing the gear having reduced NVH. The step of Manganese phosphating includes: hot-soaking a gear;
de-greasing the hot soaked gear; cascade rinsing the de-greased gear; activating the rinsed gear; and Manganese phosphating the activated gear. The step of vibro finishing includes: cascade rinsing the Manganese phosphate gear followed by the vibro finishing. The hot soaking is carried out at the temperature ranges between 600 to 1200. The hot rinsing is carried out at the temperature ranges between 600 to 1200. At the step of cascade rinsing the pressure ranges between 60 to 180 bar. Manganese phosphating and vibro-finishing in hypoid gears provide NVH up to 5dBA axle with noise reduction. The process of surface finishing is for hypoid gear.

BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 shows a hypoid gear of prior art;
FIG. 2 shows a hypoid gear processed with surface-finishing in accordance with the present invention; and
FIG. 3 shows a schematic flow chart of the process of surface finishing in accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth relating to specific components to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated elements, modules, units and/or components, but do not forbid the presence or addition of one or more other elements, components, and/or groups thereof.
The present invention realtes to a surface finishing process for gears.
Referring to FIG. 1, a hypoid gear with respect to prior art is shown. The hypoid gear used in the industry have coating or finishing that does not help to reduce NVH.
Referrring to FIG. 2, a hypoid gear in accordance with an embodiment of the present invention is shown. The hypoid gear transfers load from propeller shaft to rear drive shafts or wheel. The hypoid gears undergo Manganese phosphating followed by vibro finishing that improves lubrication and results in lower surface finish or low sliding forces and wear.
Referring to FIG. 3, steps of the process for surface-finishing of the gear is shown. The process for surface-finishing of the gears includes the steps of Manganese phosphating the gear followed by vibro-finishing the Manganese phosphated gear. In the next steps the gear undergoes hot rinsing; coating the gear with the rust proofing oil; and drying the coated gear by hot air thereby providing the gear having reduced NVH.
The Manganese phosphating includes the following step. In first step, a part i.e the gear undergoing the process is loaded on the machine. In the next step, the part is hot soaked and de-greased. In the stage of hot soaking the metal is heated slowly to just below the temperature where the internal structure undergoes change, and hold it until the temperature is consistent throughout the metal. The temperature ranges between 600 to 1200 during the hot soaking. The de-greasing is performed for removing all residuals of greasing process.
In the next step, the part undergoes cascade rinsing i. e the part is washed in overflowing water tank. In the next step, an activation process is initiated. In this step, fine active crystal centres are provided on the surface of the metal which helps attaining a uniform phosphate coating at phosphating stage. In the next step, the part undergoes the step of Manganese phosphating followed by cascade rinsing. During cascade rinsing, the pressure ranges between 80 to 160 bar. After phosphating, the hot rinsing of the part takes place. The temperature ranges between 600 to 1200 during the hot rinsing. In the next step, the part is coated with the rust proofing oil.
In the next step, the gear undergoes vibro-finishing. The vibro-finishig with optimised process time; improves surface finish. In the last step, the part coated with rust proofing oil is dried by hot air and unloaded from the machine. In accordance with the present invention, Manganese phosphating and vibro-finishing in hypoid gears provide reduced NVH up to 5dBA axle with noise reduction. The initial wear and friction is lowered. The drive train losses are reduced up to approximately 0.15 kW. The hypoid gears of the present invention have reduced Gear wear & hence better durability. The approximate time required for the each step is 3 min to 5 min.
Combination of Vibro-finishing with optimised process time; reduces surface finish which helps to reduce frictional forces. Subsequently manganese phosphating provides lubricating film further reducing frictional forces during gear operation. Combination of two processes together prolong gear durability by reducing chances of gear scoring which helps to avoid noise increase after gear operation.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
Any discussion of devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
,CLAIMS:
1. A process for surface-finishing of the gears comprising the steps of:
Manganese phosphating the gear;
vibro-finishing the Manganese phosphated gear;
hot rinsing the gear;
coating the gear with the rust proofing oil; and
drying the coated gear by hot air thereby providing the gear having reduced NVH.

2. The process as claimed in claim 1, wherein the step of Manganese phosphating includes:
hot-soaking a gear;
de-greasing the hot soaked gear;
cascade rinsing the de-greased gear;
activating the rinsed gear; and
Manganese phosphating the activated gear.

3. The process as claimed in claim 1, wherein the step of vibro finishing includes:
cascade rinsing the Manganese phosphate gear followed by the vibro finishing.
4. The process as claimed in claim 2, wherein the hot soaking is carried out at temperature ranges between 600 to 1200.

5. The process as claimed in claim 1, wherein the hot rinsing is carried out at temperature ranges between 600 to 1200.

6. The process as claimed in claim 2 or 3, wherein the cascade rinsing is carried out at a pressure ranges between 60 to 180 bar.

7. The process as claimed in claims 1-6, wherein the gear is a hypoid gear.

8. The process as claimed in claims 1-7, wherein manganese phosphating and vibro-finishing in hypoid gears provide NVH up to 5dBA axle with noise reduction.