Field of the Invention

The present invention relates to a unique arrangement for uniform polishing of narrow complex profiles of miniature gear. More particularly, the present invention relates to the unique arrangement for uniform polishing of narrow complex profiles of miniature gear by rotational-magnetorheological fluid-based finishing process. This invention relates to the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein the magnet fixture setup consists of four magnets to give concentric and uniform magnetic field distribution in the desired finishing region. The present invention relates to the unique arrangement for uniform polishing of narrow complex profiles of miniature gear having an advantages of without any defects, any grinding lines, and residual stresses.

Background of the invention and related prior Art

Because hardware is before making finished product, the pore of its piece surface can cause finished surface brightness, so the preceding program that all can carry out one polishing that hardware is peddled in the market, make its surface more smooth and bright, and heavy parts all is stained with suitable abrasive material with polishing cloth at present, the program of polishing, if but miniature parts is stained with the program that abrasive material polishes with polishing cloth, except polishing effect is good, do not lose time yet, so present common burnishing device, all be with a polygonal cylinder, great quantity of small part and suitable mill amount are inserted, the polygon cylinder that rolls then, and miniature parts just can reach the effectiveness of its piece surface of polishing.
The magnetorheological polishing (MRP) fluid is a smart fluid that changes its property according to the nature of the applied magnetic field, has found a multitude of applications in modern manufacturing sectors. Some of these applications include optics manufacturing, dampers, brakes, clutches, hydraulic valves, seals, composite structures and polishing devices. Nanoscale finishing of large scale parts with complex geometric features through magnetorheological fluid-based finishing process is perhaps the most effective application of MRP fluid.
In modern industries, requirements for miniature/micro-sized components are increasing on a daily basis. These individual miniature components are highly utilized in tiny/remote machine systems. One of the highly used applications of these miniature components is miniature gears. These miniature gears have huge applications in small servo motors, drones (used in military applications), UAVs (used in aerospace and mining industries), infusion pumps (used in biomedical equipment), and Swiss watches etc. These Swiss watches, drones, UAVs and infusion pumps are highly sophisticated components. During the infusion process in blood vanes, if the gear system fails, it can cause severe problems. In Swiss watches, changing the gear systems itself is very costly. If these gear systems will not do smooth power transfer during military operations, these operations can fail due to their noise and vibrations. The uniform super-finishing on the miniature gear profiles makes the gears do smooth power-transfer without any noise or vibrations, increases the wear and corrosion resistance, reduces the backlash problems, and extends its service life more than 15 times. Because of the vast applications and easy unavailability of these kinds of super-finished high-quality miniature gears, the current invention will draw the attention of large gear- manufacturer industries. The super-finishing of the miniature gear through the current invention is relatively cheaper, efficient and less time-consuming.
The document CN200991847 said a drum type polishing device, which can be used to polish the surface of the small-size parts and remove the pores on the surface of the small-size parts and thus makes the surface of the small-size parts shiny and can effectively lower the damaging rate when polishing the small-size parts so as to increase the product value of the parts. It is mainly characterized in that: a transmission wheel drives a plurality of polygonal drums that are arranged by group on a rotary table in order to make the polygonal drum revolve along the circumferential direction, which can make the surface of the small-size parts which are arranged inside the polygonal drum polished by the abrasives; and a planetary mechanism, which is combined by a plurality of relay gearwheels and the positioning gearwheel of an medial axis, makes the polygonal drum not to turnover, which can produce the centerless turnover effect, and then a polishing function can be quickly and effectively achieved.

According to the document US2586334 to provide an equipment and a method of procedure to polish, by generating action, the finish ground surfaces of lens blanks mounted in multiple on a spherical carrier thereby effectuating the complete processing of optical surfaces, including rough and finish grinding, also polishing, by the equatorial generating system, which requires that each lens blank be mounted on a spherical carrier but twice for the complete processing of both of its refracting surfaces.

The invention of the document US 4173851is directed to an improved barrel polishing process is disclosed in which pieces or parts mounted in a rotary barrel on spindles carried by the head thereof are passed through the abrasive layer formed in the barrel. The pieces are forced to turn around a vertical shaft while turning on their own axis so that they pass alternately through a denser portion of the abrasive layer and through a coarser portion. This ensures a uniform finishing of the pieces.
The other document JP2012246513 illustrates a stent polishing apparatus 10 includes an inclined tank 11 for flowing a polishing liquid PL from upstream to downstream, and a transport unit that immerses the stent 69 in the polishing liquid PL and transports the stent 69 while rotating from downstream to upstream.
There are three significant aspects to this technology, the orientation of four magnets to generate the required value of the concentric magnetic field at the finishing profiles of the miniature gear, flow restrictor for uniform polishing, workpiece fixture to tightly hold the flow restrictor and miniature gear parallelly. The exact requirement of the magnetic field for miniature gear profiles polishing is initially confirmed by magnetostatic simulation analysis and later by experimental analysis. An initial uniform gap of 2 mm thickness between flow restrictor and miniature gear profiles is kept to easily pass the MRP fluid across the miniature gear profiles. This much amount of thick MRP fluid ensures the maximum amount of abrasive particles to get effective contact with miniature gear profiles and, thus, better process economics. The optimum distributions of abrasives in MRP fluid will quickly remove the undulations of gear profiles to give fine smooth surfaces.
The magnet characteristics such as locations, orientations, sizes of magnets and strength of magnets affect process efficiency and surface finishing performance. The magnets should be at their optimum location; otherwise, the required amount of uniform magnet field at gear profiles will not be present. Also, magnets should have a specific orientation; it means that in which orientation the magnet north pole should be facing or the south pole should be facing will be decided, based on the uniformity in magnetic field distribution. Sizes of the magnet will also have another effect on magnetic field distribution; its size variation will decide the size of the magnet fixture. The rotational movement of magnets and flow restrictor will nullify the spatial variation of magnetic field distribution at miniature gear finishing profiles for uniform polishing. This uniform polishing improves the corrosion resistance and strength of the miniature gear.
Generally, small gears manufactured by a hobbing process have different kinds of defects like burrs, dents, cracks, pits and other manufacturing defects. These defects deteriorate the quality of the gear. The small gear is difficult to polish in conventional processes (shaving, grinding, honing and lapping) due to its complex geometry, vulnerability and the narrow passageway between the gear tooth. Conventional processes like grinding produce thermal harm (burning) and transverse grinding lines, which causes noise, vibration, excessive stress or reduced fatigue life in gear during meshing. The gear shaving process is mostly used to finish soft material straight and helical spur gears with less processing time; however, it gives a low precision profile. Gear honing shortens the service life of the gear. Gear lapping has a very less material removal rate. Electrochemical honing (ECH), electrochemical grinding (ECG) and pulse electrochemical mechanical polishing (PECMP) processes can polish the macro gear, but not miniature gears surface up to 50 nm (Ra). The ultrasonic-assisted abrasive flow machining (UAAFM) and chemically accelerating vibratory surface finishing (CAVSF) processes are used to finish the macro bevel and helical gear. Low-value surface roughness (under 0.1 µm) significantly reduces friction between meshing teeth, thus improves service life.

Summary of the invention

The present invention relates to a unique arrangement for uniform polishing of narrow complex profiles of miniature gear. More particularly, the present invention relates to the unique arrangement for uniform polishing of narrow complex profiles of miniature gear by rotational-magnetorheological fluid-based finishing process. This invention relates to the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein the magnet fixture setup consists of four magnets to give concentric and uniform magnetic field distribution in the desired finishing region. The present invention relates to the unique arrangement for uniform polishing of narrow complex profiles of miniature gear having an advantages of without any defects, any grinding lines, and residual stresses.

Detailed description of the invention

For the purpose of facilitating an understanding of the invention, there is illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, the invention, its construction and operation, and many of its advantages should be readily understood and appreciated. The drawings are in seven sheets.

The principal object of the present invention is to provide a unique arrangement for uniform polishing of narrow complex profiles of miniature gear.
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear which consists of
a) magnet fixture which consists of four magnets to give concentric and uniform magnetic field distribution in the desired finishing region;
b) a uniform flow restrictor,
c) a fixture for holding the miniature gear component and flow restrictor to uniformly distribute the incoming MR polishing media across the profiles of miniature gear component,
d) a fixture wherein two flanges in which one is the male part, and the other is the female part, and
e) two brass cylinders, which are kept inside the workpiece fixture to support the uniform flow restrictor and correctly place it parallel to miniature gear profiles.


Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein magnet fixture is made of aluminum.
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein gear fixture is made off brass.
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein the bottom (8) and top (11) fixtures are the support for the workpiece fixture and create a fluid channel to flow the MRP media across the miniature gear component.
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein the permanent magnets are Nd-Fe-B of grade (48).
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein a magnet are fixed through Allen bolts.
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein four magnets where the same magnetic poles are facing each other to get the required and uniform value of magnetic field distributions.
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein the gap between the flow restrictor and gear component profiles is uniformly maintained at about 2 mm.
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein on both flanges, holes are left to pass the MRP fluid across the miniature gear profiles.
Another object of the present invention is to provide the unique arrangement for uniform polishing of narrow complex profiles of miniature gear wherein a bearing (9) is attached to the bottom fixture (8) for successfully fitting the magnet fixture (2) on it and concurrently used for rotating the magnet fixture (2) easily.

The novel features that are considered characteristic of the present invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of certain specific embodiments, when read in connection with the accompanying drawings, in which:

FIG. 1 illustrates the magnet fixture, workpiece fixture and comprehensive setup of the rotational-magnetorheological fluid-based finishing process of the present invention;
FIG. 2 illustrates the fixture for tightly holding the four magnets of the present invention;
FIG. 3 illustrates the workpiece fixture with a miniature gear component and uniform flow restrictor of the present invention;
FIG. 4 illustrates the bottom flange or male part of the workpiece fixture of the present invention;
FIG. 5 illustrates the top flange or female part of the workpiece fixture of the present invention;
FIG. 6 illustrates the brass cylinder which will be placed inside the workpiece fixture to support the uniform flow restrictor (4) of the present invention;
FIG. 7 illustrates the fixtures (8, 11), which are used to hold the workpiece fixture and simultaneously creates a channel (10, 10a) for MR fluid to flow across the gear component of the present invention;
FIG. 8 illustrates the miniature gear and uniform flow restrictor, placed parallelly with a uniform working gap of 2 mm (12), for the restricted flow of MR fluid of the present invention;
FIG. 9 illustrates the flow of MRP fluid along the surface in a flow restrictor (an exact negative replica of gear profiles)of the present invention;
A uniform flow restrictor and workpiece fixture for the rotational magnetorheological fluid-based finishing process of miniature spur gear profiles is disclosed here. Four magnets at designated orientations are properly attached inside the aluminium fixture with the help of Allen bolts. These four magnets at the optimum distance from the centre of the magnet fixture ensure the concentration of the required value of the magnetic field at the finishing profiles of the miniature gear. A uniform flow restrictor is designed and developed, which is an exact negative replica of miniature gear, to forcefully pass the magnetorheological polishing (MRP) fluid across each profile of miniature gear uniformly; thus, uniform finishing takes place across each gear profile (5). The workpiece fixture is also designed and fabricated to tightly hold the miniature gear and flow restrictor in such a way that they are placed parallelly (4, 5). The gap between miniature gear and flow restrictor is left as 2 mm (12) to easily pass MRP fluid across the miniature gear profiles.
The current invention, disclosed herein, offers one possible solution to the aforesaid mentioned issues. The setup eliminates all manufacturing defects and polishing defects created by conventional polishing processes and gives super smooth uniform polishing for miniature gear profiles. Since the gap between the gear profile surfaces and cylindrical fixture inner surface is variable along the flow direction of medium flow. And, also each profile of gear tooth is at a different distance from the centre of magnets; thus, the spatially varying magnetic field is observed at gear tooth profiles. So, the flow of fluid in the simple cylindrical fixture setup separates. This separation of flow from the gear workpiece may result in the formation of dead zones that are the regions on the workpiece surface where the removal of material is very low (almost zero) due to the insufficient or ineffective flow of the medium. To ensure a more regulated flow along the gear profiles, a flow restrictor (an exact negative replica of gear profiles) is developed and used to guide the flow of MRP fluid along the surface to be finished, as shown in the figure (9).
The gear and flow restrictor fixture are kept in-between the magnet fixture. This whole setup (13) is used for the rotational-magnetorheological fluid based finishing process, where the magnet fixture is rotating, and two media cylinders attached vertically are used to keep MRP fluid. This MRP fluid is pushed by hydraulic pressure cylinders in an upward and downward direction to pass across the gear profiles uniformly. The controllability of finishing forces only at the finishing profile of miniature gear helps in getting uniform polishing. This setup would help the fluid flow to enhance MRR and finishing rate (FR), reduce dead zones and improve the effectiveness of the magnetic field.
The present invention, disclosed herein, is in context to deliver a uniformly smooth surface finish throughout the polishing miniature gear profiles without any defects, any grinding lines, and residual stresses. The magnet fixture setup consists of four magnets to give concentric and uniform magnetic field distribution in the desired finishing region. The optimum location, size, orientations and strength of magnets will help to give optimum magnetic field at the desired finishing complex profiles of the miniature gear. The rotation of magnets will nullify the spatially varying magnetic field at the miniature gear finishing profiles. To ensure a more regulated flow along the gear profiles, a flow restrictor (an exact negative replica of gear profiles) is developed and used to guide the flow of MRP fluid along the surface to be finished (5). The workpiece fixture is used to hold the gear component and flow restrictor tightly. The brass cylinder (7) is kept inside the workpiece fixture to support the uniform flow restrictor and correctly place it parallel to miniature gear profiles. The setup with all its components is illustrated in Fig. 1.
Continuing with reference to the drawings, Fig. 2 schematically illustrates a magnet fixture with its various details. Space is left in the magnet fixture (2e) for tightly holding the permanent Nd-Fe-B magnets (2a). These four magnets will concentrate the required magnetic field on the finishing profiles (5) of the miniature gear. The belt-like pattern (2b) is made on the bottom of the magnet fixture for connecting the belt from the magnet fixture to the induction motor. This belt arrangement in the setup will help to rotate the magnets at desired rotational speeds. The hollow space (2d) in the middle is left to cross the workpiece fixture and connect it to the media cylinder. The Allen bolt (2c) is used to rigidly fix the permanent magnets in the magnet fixture.
Fig. 3 shows the workpiece fixture (3, 6), which is used to hold the gear and uniform flow restrictor tightly. The eight holes (3a) is made on both flanges of the workpiece fixture for easily flowing the MRP media across the miniature gear profiles. The bottom flange is the male part, and the top flange is the female part of the workpiece fixture.
Fig. 4 shows the bottom flange of the workpiece fixture, which is used to place the flow restrictor and gear parallelly. The extrude part (6a) in the bottom flange is made of 4 mm diameter to place miniature gear exactly in the centre. The miniature gear will be simply placed on the base (6b) of the extruded part. The base is also made for placing and aligning (6d) the female part of the workpiece fixture concentrically to the female part. The holes are left in the bottom flange to easily flow the MRP media into the workpiece fixture across the gear profiles.
Fig. 5 shows the top flange of the workpiece fixture, which is used to tightly fit the flow restrictor and miniature gear component by perfectly mating with the bottom flange. The groove part (3c) in the top flange is made to perfectly fit the extruded part of the bottom flange exactly in the centre. The miniature gear will be simply placed on the base (3d) of the groove part. The base is also made for placing and aligning (3e) the male part of the workpiece fixture concentrically to the male part. The holes (3a) are left in the bottom flange to easily flow the MRP media into the workpiece fixture across the gear profiles. Fig. 6 show the brass cylinder (7) having the support (7a) for the uniform flow restrictor, which is kept in both flanges.
Fig. 7 shows the schematic of the fixtures (bottom (8) and top (11)), which is used to properly hold the workpiece fixture in between the bottom and top polishing media cylinder. These fixtures have a circular channel to flow the MRP media across the gear component. These fixtures are medium for fluid flow. A bearing (9) is attached to the bottom fixture (8) for successfully fitting the magnet fixture (2) on it and concurrently used for rotating the magnet fixture (2) easily.
Fig. 8 shows the schematic of the gear (5) and uniform flow restrictor (4), which is made of steel material. The flow restrictor is an exact negative replica of the miniature gear workpiece. This uniform flow restrictor is made according to the profiles of the gear workpiece. The uniform gap (12) between miniature gear and flow restrictor is maintained for the restricted flow of MRP media across miniature gear profiles.

The present disclosure should be considered as illustrative and not restrictive in character. It is understood that only certain embodiments have been presented and that all changes, modifications, and further applications that come within the spirit of the disclosure are desired to be protected.

Claims:

1) A unique arrangement for uniform polishing of narrow complex profiles of miniature gear which consists of
a) magnet fixture which consists of four magnets to give concentric and uniform magnetic field distribution in the desired finishing region;
b) a uniform flow restrictor,
c) a fixture for holding the miniature gear component and flow restrictor to uniformly distribute the incoming MR polishing media across the profiles of miniature gear component,
d) a fixture wherein two flanges in which one is the male part, and the other is the female part, and
e) two brass cylinders, which are kept inside the workpiece fixture to support the uniform flow restrictor and correctly place it parallel to miniature gear profiles.
2) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein magnet fixture is made of aluminum.
3) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein gear fixture is made of brass.
4) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein the permanent magnets are Nd-Fe-B of grade (48).
5) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein the bottom (8) and top (11) fixtures are the support for the workpiece fixture and create a fluid channel to flow the MRP media across the miniature gear component.
6) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein four magnets in which the same magnetic poles are facing each other to get the required and uniform value of magnetic field distributions.

7) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein the gap between the flow restrictor and gear component profiles is uniformly maintained at about 2 mm.
8) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein a magnet are fixed through Allen bolts.
9) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein on both flanges, holes are left to pass the MRP fluid across the miniature gear profiles.
10) The unique arrangement for uniform polishing of narrow complex profiles of miniature gear as claimed in claim 1 wherein a bearing (9) is attached to the bottom fixture (8) for successfully fitting the magnet fixture (2) on it and concurrently used for rotating the magnet fixture (2) easily.