Claims:
1. A system for manufacturing textured metallic surfaces comprising:
a base for mounting a metal to be textured thereon;
an electrode positioned above a top surface of the metal at a predefined gap therebetween, the electrode generates sparking on the top surface of the metal thereby causing an erosion thereon;
a micro-drill connected to the electrode for facilitating texturing on the eroded surface of the metal thereby forming a plurality of microscopic structures thereon; and
a control unit connected to the electrode and the micro-drill, the control unit controls current of the electrode, the control unit controls a rotational speed of the micro-drill.

2. The system as claimed in claim 1, wherein the microscopic structures are selected from any one of straight grooves, patterned linear grooves and circular dimples.

3. The system as claimed in claim 1, wherein the electrode is a micro sized metal electrode selected from a group consisting of a brass electrode, a tellurium copper electrode, a copper tungsten electrode, a tungsten electrode and a silver tungsten electrode.

4. A method for manufacturing textured metallic surfaces, the method comprising the steps of:
a) placing a metal to be textured on a base;
b) sparking on a top surface of the metal using an electrode thereby causing erosion thereon;
c) texturing on the eroded surface of the metal using a micro-drill to produce microscopic structures, the microscopic structures being selected from any one of straight grooves, patterned linear grooves and circular dimples thereon; and
d) removing excess metal particles,
wherein, the erosion resulting in any one of a molten soft condition and an oxidation of the top surface of the metal, the micro-drill removes oxides from the top surface of the metal thereby facilitating formation of the microscopic structures having uniform geometry.

5. The method as claimed in claim 4, wherein the sparking is carried out in any one of an ordinary environment, a gaseous inert environment and a liquid medium.
6. The method as claimed in claim 5, wherein the gaseous inert environment is selected from any one of Argon, Helium and other gases that do not react with the metal to be textured.

7. The method as claimed in claim 5, wherein the liquid medium is selected from any one of water based medium, oil based medium and any other chemicals and mixtures thereof.
, Description:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)

&

THE PATENTS RULE, 2003

COMPLETE SPECIFICATION
[See section 10, Rule 13]

SYSTEM AND METHOD FOR MANUFACTURING TEXTURED METALLIC SURFACES;

MAHINDRA & MAHINDRA LIMITED, AN INDIAN COMPANY HAVING ADDRESS: MAHINDRA & MAHINDRA LIMITED, MAHINDRA RESEARCH VALLEY (MRV), MAHINDRA WORLD CITY, ANJUR (PO), CHENGALPATTU - 603 204, KANCHEEPURAM DIST, (TAMIL NADU) INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND MANNER IN WHICH IT IS TO BE PERFORMED
Field of the invention:
The present invention relates generally to surface enhancement technologies and more particularly, to a system and a method for manufacturing textured metallic surfaces.
Background of the invention:
Surface texture, also referred as patterned surface microstructure, is an important factor that controls friction and transfer layer formation during sliding. The textured surface is commercially deployed in various domains such as hydraulics, seals, thrust bearings, magnetic storage devices, MEMS devices, engines, bone and dental implants and the like. There are considerable efforts seen in the art to study influence of the surface texture on the friction and wear during the sliding conditions as the surface texture provides variety of properties for industrial applications. It is well known fact that the surface texture of microscopic sizes on solid materials influences variety of properties such as a load bearing capacity, a wear volume, lubrication and the friction during sliding.
Several factors influence an outcome of the textured surface such as a lubricant viscosity, a micro-pore geometry and area, a relative contact velocity, pressure and the like. The common microstructures are formed in form of linear and crossed grooves, and generally have circular dimple-like depressions. The surface texture improves adhesion and decreases reflectivity of the surface for some specific applications. One such application is to improve the friction, wear and the load bearing capacity of two rubbing solid materials such as a journal bearing in presence of a lubricant. In such application, circular micro cavities act as a miniature hydrodynamic bearing during relative motion between two solid contact surfaces thereby generating pressure gradient in each pore. The pressure gradient is modelled using Reynold's averaged Navier-Stokes equation. Relative motion combined with shear force creates pressure profile due to wedge effect in the presence of the lubricant film and also provides an effective sink for debris particles generated during the sliding. During lubricant starved condition, the circular micro cavities act as a storage area for the lubricant.
Currently, texturing is accomplished by various methods such as an abrasive jet machining, a laser texturing, an electrical discharge machining, an ion beam texturing, a vibro-rolling, a reactive-ion etching and the like. However, the prior art systems and methods involve high capital cost of the system.
Accordingly, there exists is a need of a system and a method for manufacturing textured surfaces that overcomes the above mentioned drawbacks of the prior art.
Summary of the invention:
Accordingly, in one aspect, the present invention provides a system for manufacturing textured metallic surfaces. The system comprises at least one arrangement that comprises a base, an electrode, a micro-drill and a control unit. The base is used for mounting a metal to be textured thereon. The electrode is positioned above a top surface of the metal at a predefined gap therebetween and adapted to erode the surface of the metal by generating sparks thereon. The electrode is a micro sized metal electrode selected from a group consisting of a brass electrode, a tellurium copper electrode, a copper tungsten electrode, a tungsten electrode and a silver tungsten electrode. The micro-drill is operably connected to the electrode for facilitating texturing on the eroded surface of the metal to produce microscopic structures. The microscopic structures are selected from any one of straight grooves, patterned linear grooves and circular dimples. The control unit is operably connected to the electrode and the micro-drill. The control unit is adapted to control current of the electrode and a rotational speed of the micro-drill.
In another aspect, the present invention provides a method for manufacturing textured metallic surfaces. The method involves an initial step of placing the metal to be textured on the base of the system. In next step, the method involves sparking on a top surface of the metal using the electrode thereby causing erosion thereon. Preferably, the sparking is carried out in any one of an ordinary environment, a gaseous inert environment and a liquid medium. The gaseous inert environment is selected from any one of Argon, Helium and other gases that do not react with the metal to be textured. The liquid medium is selected from any one of water based medium, oil based medium and any other chemicals and mixtures thereof. In further step, the method involves texturing on the eroded surface of the metal using the micro-drill to produce microscopic structures. The microscopic structures are selected from any one of the straight grooves, patterned linear grooves and circular dimples. Moreover, the method involves removal of excess metal particles. In the context of the present invention, the erosion results in any one of a molten soft condition and an oxidation of the surface of the metal, and the micro-drill removes oxides from the surface of the metal thereby facilitating formation of the microscopic structures having uniform geometry.
Brief description of the drawings:
Figure 1 shows a schematic diagram of a system of manufacturing textured metallic surfaces, in accordance with the present invention;
Figure 2 shows another schematic diagram of the system of manufacturing textured metallic surfaces, in accordance with the present invention; and
Figure 3 shows a flowchart of a method of manufacturing textured metallic surfaces, in accordance with the present invention.
Detailed description of the invention:
The invention described herein is explained using specific exemplary details for better understanding. However, the invention disclosed can be worked on by a person skilled in the art without the use of these specific details.
References in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
References in the specification to “preferred embodiment” means that a particular feature, structure, characteristic, or function described in detail thereby omitting known constructions and functions for clear description of the present invention.
In general aspect, the present invention describes a system and a method for manufacturing textures/patterned surface microstructure on a metallic surface by conjoint effect of a spark process and a drill process in the presence or absence of liquid or gaseous medium.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.
Referring to figures 1-2, in one aspect, a system (50) for manufacturing textured metallic surfaces in accordance with the present invention is shown. The system (50) is designed to produce textured metallic surfaces that are used in various applications such as, for example, for decoration purposes, for better adhesion, for reducing reflectivity of the surfaces, to reduce friction between two sliding parts in presence of lubricating oil and in electronic devices.
The system (50) comprises at least one arrangement/unit. However, it is understood that the system (50) may include any number of arrangements as per the metal to be textured and productivity rate requirements. The at least one arrangement (hereinafter “the arrangement”) comprises an electrode (10), a micro-drill (20) and a control unit (30). All the components of the arrangement are operably connected to each other. The arrangement has a base that is utilized for placing a metal (60) to be textured thereon.
The electrode (10) is positioned above a top surface of the metal (60) at a predefined gap therebetween. The gap is filled with a dielectric medium. The electrode (10) is adapted to erode the surface of the metal (60) by generating sparks thereon. In an embodiment, the electrode (10) is a micro sized metal electrode. The metal electrode is selected from a group consisting of a brass electrode, a tellurium copper electrode, a copper tungsten electrode, a tungsten electrode and a silver tungsten electrode. The electrode (10) has a diameter and a length in a range of 1 to 1000 microns. The electrode (10) has a point angle in a range of 90-180 degrees. However, it is understood that any other suitable electrode of any other size may be used in other alternative embodiments of electrode (10), as per the metallic surface to be textured.
The micro-drill (20) is operably connected to the electrode (10) for facilitating texturing on the eroded surface of the metal (60) to produce microscopic structures (70). The microscopic structures (70) are selected from any one of the following patterns such as the straight grooves, the patterned linear grooves and the circular dimples. The micro-drill (20) is actuated by a motor or other rotary mechanism and preferably controlled by a computerized numerical control (hereinafter “the CNC”) (not shown). The speed of rotation of the micro-drill (20) is in a range of 1-100 million RPM.
The control unit (30) is operably connected to the electrode (10) and the micro-drill (20). The control unit (30) controls current of the electrode (10) and rotational speed of the micro-drill (20). In another embodiment, the control unit (30) may be connected to a communication device (not shown) such as a computer to ensure production of the microscopic structures (70) that are equally distributed throughout the metallic surface.
In yet another embodiment, the system (50) may include a plurality of arrangements, a plurality of electrodes and a plurality of micro-drills that are arranged according to a profile/contour of the surface to be textured. The plurality of arrangements facilitates faster texturing thereby covering all types of contours and areas on the surface of the metal (60).
In another aspect, a method for manufacturing textured metallic surfaces comprising:
a) placing a metal to be textured on a base of the system;
b) sparking on a top surface of the metal using an electrode of the system thereby causing an erosion thereon;
c) texturing on the eroded surface of the metal using a micro-drill to produce microscopic structures, the microscopic structures being selected from any one of straight grooves, patterned linear grooves and circular dimples thereon; and
d) removing excess metal particles.
Now referring to figure 3, a detailed method (200) for manufacturing textured metallic surfaces is described in detail hereinafter:
The method (200) is described in conjunction with the system (50). The method (200) starts at step (110) as shown. In next step (120), the surface of the metal (60) to be textured is placed on the base of the system (100). In another embodiment, the method (200) may involve pre-treatment of the metal (60) to be textured before placement on the base. It is understood however that the pre-treatment is carried out such that the metal (60) does not become resistant to the sparking erosion.
At step (130), the top surface of the metal (60) is sparked using the electrode (10) thereby causing erosion thereof. The erosion results in any one of a molten soft condition and an oxidation of the top surface of the metal (60). In the context of the present invention, the electrode (10) has a diameter and a length in a range of 1 to 1000 microns. The electrode (10) has the point angle in a range of about 90-180 degrees. The electrode (10) is provided with a current of 1-100 Amps. It is understood that the sparking through the electrode (10) is carried out in an environment selected from an ordinary environment, a gaseous inert environment and a liquid medium. The gaseous inert environment preferably includes any one of Argon, Helium or other inert gases that do not react with the metal (60) to be textured. In the gaseous inert environment, the flow rate of gases is maintained in a range of 0.001-1 million CC/sec. The liquid medium is selected from any one of water based medium, oil based medium and any other chemicals and mixtures thereof. In the liquid medium, the flow rate of the liquid is maintained in a range of 0.001-1 million CC/Sec.
In next step (140), the method (200) involves texturing on the eroded surface of the metal (60) using the micro-drill (20) to produce microscopic structures (70). The microscopic structures (70) are selected from any one of the straight grooves, the patterned linear grooves and the circular dimples. The micro-drill (20) is actuated by a motor or other rotary mechanism controlled by the CNC. The speed of rotation of the micro-drill (20) is in a range of 1-100 million RPM.
At step (150), removal of excess metal particles/debris is carried out automatically by the force of the flow of dielectric medium. Accordingly, the textured metallic surfaces in accordance with the present invention are obtained in the step (160).
Advantages of the invention:
1. The system (50) and the method (200) facilitate formation of smooth profile geometry of the microscopic structures (70).
2. The system (50) and the method (200) are cost effective and require less capital expenditure as compared to laser systems used in the prior art.
3. The system (50) and the method (200) facilitate effective removal of machined debris.
4. The system (50) is designed to accommodate the plurality of arrangements thereby facilitating higher productivity.
5. The maintenance of the system (50) is much easier as compared to the laser systems used in the prior art.
The foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.
The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others, skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated.
It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.