FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Machine for Finishing Internal Surface using Backed Abrasives Film and
Method therefor"
2. APPLICANT:
(a) NAME: Grind Master Machines Pvt. Ltd.
(b)NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: B10/B11/B14, MIDC. Railway Station,
Aurangabad 431005, Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Machine for Finishing Internal Surface using Backed Abrasives Film and
Method therefor
Field of the invention
The present invention relates to a metal surface finishing and more particularly, to an improved machine and a method for microfinishing an internal surface using a film of backed abrasives.
Background of the invention
Microfinishing is an abrasion process in which an abrasive belt is brought to stand against a work piece which has been previously rough ground or turned. Various technologies of surface microfinishing are available in the prior art, for example, stone microfinishing or honing that involves direct contact of an abrasive stone or an abrasive stick with the surface to be machined. Stone microfinishing is generally used to finish internal cylindrical surfaces, for example, to finish bores of cylinders of IC engine, hydraulic cylinders, gas barrels, bearings, and the like. However, this method has disadvantages like honing stones need to be adjusted after every few cycles because of wear. Also, the honing stones sometimes crack being brittle causing small pieces of the stone to break loose and forcing them between the work piece and produce chatter marks and tearing.
Accordingly, there exists a need to provide a machine and a method of microfinishing for producing superior quality internal surface finishes that overcomes the drawbacks of the prior art.
Object of the invention

An object of the present invention is to produce superior quality finishes using a film of backed abrasives.
Summary of the invention
Accordingly, the present invention provides a machine for finishing an internal surface using a film of backed abrasives. The machine comprises a base, a headstock assembly, a drive assembly, a slide assembly, a cross slide assembly, a pusher assembly, a coolant system, a pneumatic system, a lubrication system and a microfinishing attachment. The microfinishing attachment comprises a bracket, a frame, a cylinder, a plurality of rollers, an indexing unit, an oscillation assembly and a shoe assembly.
The bracket is positioned on the cross slide assembly. The frame is positioned on an extended side of the bracket using a first set of plurality of cap screws and a dowel pin. The cylinder is secured on a top surface of the frame. The plurality of rollers is mounted on the bracket and adapted for guiding the film of backed abrasives. The indexing unit is adapted for creating a slack and pulling the film of backed abrasives. The oscillation assembly is mounted on the indexing unit and used to oscillate the plurality of rollers. The cylinder and the indexing unit create a slack so that the backed abrasive film is pulled with zero tension and combination of the workpiece rotation and oscillation generate a cross hatch pattern required for microfinishing of the internal surfaces. The shoe assembly is attached at a side of the bracket. The shoe assembly includes a ring, a non-metallic insert and a plurality of clips. The ring is adapted for passing the film of backed abrasives thereon. The non-metallic insert is positioned on the ring for ensuring movement of the film of backed abrasives in point contact with a workpiece to be microfmished. The plurality of clips mounts the shoe assembly on to the bracket. In another aspect, the

present invention provides a method for finishing an internal surface using a film of backed abrasives on the machine. The method comprises setting the headstock assembly and the pusher assembly at a return position, loading a workpiece to be microfinished on an internal diameter collet manually and starting an automatic cycle of microfmishing. The automatic cycle of microfinishing comprises a first operational cycle, a second operational cycle and a third operational cycle.
In the first operational cycle, the pusher assembly advances for pushing the workpiece to a correct location and the headstock retracts to an original position and starts rotation thereby causing rotation of the workpiece and the microfinishing attachment approaches to the location where polishing operation is to be carried out. In the second operational cycle, the film of backed abrasives moves over the ring guided by the plurality of rollers and the cylinder moves down to create the tightness in the film of backed abrasives, the workpiece then advances with the headstock towards a position where polishing operation is to be carried out. In the third operational cycle, the microfinishing attachment again advances towards the workpiece thereby completing polishing of the workpiece and retracts thereby completing the automatic cycle of the microfinishing.
Brief description of the drawings
Figure 1 is a front perspective view of a microfinishing machine, in accordance with the present invention;
Figure 2 is a rear perspective view of the microfinishing machine of figure 1;
Figure 3 is a top cross sectional view of the microfinishing machine of figure 1;

Figure 4a is a front perspective view of a headstock assembly of the microfinishing machine of figure 1 showing a drive unit and a spindle;
Figure 4b is a rear perspective view of the headstock assembly of figure 4a;
Figure 5 is a top cross sectional view of a slide assembly of the microfinishing machine of figure 1;
Figure 6 is a side perspective view of a pusher assembly of the microfinishing machine of figure 1;
Figure 7 is a front perspective view showing a microfinishing attachment of the microfinishing machine of figure 1;
Figure 8 shows a rear perspective view of the microfinishing attachment of figure 7; and
Figure 9 is a perspective view of a shoe assembly of the microfinishing attachment of figures 7 and 8.
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, tecfiniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention provides an improved machine for microfinishing of an

internal surface using a film of backed abrasives. The present invention also provides an improved method for microfinishing of an internal surface using the film of backed abrasives. The machine and the method of the present invention provide superior quality reliable finishes.
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, a machine (200) for microfinishing of an internal surface is shown. The machine (200) comprises a base (10), a headstock assembly (20), a slide assembly (30), a cross slide assembly (40), a pusher assembly (50), a coolant system (60), a pneumatic system (70), a lubrication system (80) and a microfinishing attachment (120).
The base (10) is a heavy-duty steel structure fabricated out of mild steel flats and plates. The base (10) includes mounting surfaces that are machined to ensure flatness. All components and sub-assemblies of the machine (200) are mounted on the base (10).
The headstock assembly (20) is mounted on a left-hand side of the machine (200). The headstock assembly (20) includes a drive unit (12) and a spindle (14). The spindle (14) is adapted to turn a component/workpiece to be micro finished. To clamp and rotate the workpiece to be microfinished. an Internal Diameter (ID) collet (not shown) is used. The ID collet is positioned inside the spindle (14). In an embodiment, the spindle (14) is hollow and holding elements (not shown) of the ID collet are positioned at a front of the spindle (14) and a shaft (not shown) actuating the ID collet passes through the hollow spindle (14). The drive unit (12) is adapted

to drive the spindle (14) of the headstock assembly (20) at a required speed. In an embodiment, the drive is given through a motor (not shown) by a 'timer' belt (16).
The slide assembly (30) is positioned below the headstock assembly (20) to advance and retract the headstock assembly (20) and the workpiece clamped on the ID collet to a location where polishing operation is performed. In an embodiment, distance travelled by the slide assembly (30) varies as per the thickness of the workpiece. Position of the headstock assembly (20) is set by an input given to a CNC (not shown) and by means of a servo motor (not shown) of the slide assembly (30). Thus the slide assembly (30) moves in forward and reverse direction by a ball screw (25).
The cross slide assembly (40) is positioned below the microfinishing attachment (120). The cross slide assembly (40) assists the microfinishing attachment (120) to reach various polishing diameters on the workpiece as per different position of polishing diameter. Position of the microfinishing attachment (120) is set by the input given to the CNC and by means of a motor (not shown) of the cross slide assembly (40). Thus the cross slide assembly (40) moves in forward and reverse direction by the ball screw (25).
The pusher assembly (50) is designed for locating the workpiece. The pusher assembly (50) includes a nylon pad (42) mounted on a face of a pneumatic cylinder (44) that is advanced and retracted by means of the cylinder actuation. 160-mm stroke pneumatic cylinder (44) extends and retracts the nylon pad (42). The pusher assembly (50) only allows axial movement for rotation. The pusher assembly (50) is mounted and bolted on the base (10).
The coolant system (60) is provided on the machine (200) to improve work finish as well as to keep the workpiece cool while the machine (200) is in operation.

The machine (200) is equipped with the pneumatic system (70) with a Filter-Regulator-Lubricator (FRL) (not shown) and the lubrication system (80). The pneumatic system (70) provides required pressure for operation of the machine (200).
The microfimshing attachment (120) includes a bracket (82), a frame (84), a shoe assembly (92), a plurality of rollers (94), an oscillation assembly (96), an indexing arrangement/unit (98), a cylinder (100) and a first set of plurality of cap screws (110). Specifically, the microfinishing attachment (120) is a special purpose machine built in accordance with the present invention for super finishing operation of cylindrical parts.
The frame (84) is positioned on an extended side of the bracket (82) with the help of the first set of plurality of cap screws (110) and a dowel pin (112). The plurality of rollers (92) is mounted on the bracket (82) and guides the movement of the film of backed abrasives. The cylinder (100) is secured on a top surface (not numbered) of the frame (84). The indexing unit (98) is used with the cylinder (100) to create a slack so that the backed abrasive film is pulled with zero tension.
The oscillation assembly (96) is mounted on the indexing unit (98) and used to oscillate the plurality of rollers (92) during microfinishing. This is required in order to generate a good surface finish consisting of a cross hatched pattern as the combination of workpiece rotation and oscillation generate this cross hatch pattern.
The shoe assembly (92) is secured to a side of the bracket (82) by a second set of plurality of cap screws (114). The shoe assembly (92),includes a ring (86), a non-metallic insert (88) and a plurality of clips (90). In an embodiment, the ring (86) is a non-rotating stationary ring. The film of backed abrasive passes over the ring (86).

The non-metallic insert (88) is positioned on the ring (86) and ensures that the backed abrasive film moves in line contact with the workpiece.
In another aspect, a method (300) for microfmishing an internal surface using the film of backed abrasives is described. Specifically the method (300) is described in conjunction with the machine (200). In order to start the method (300), the headstock assembly (20) and the pusher assembly (50) is set at return position. In next step, the method (300) involves loading of the workpiece to be microfmished on the ID collet manually. Once the workpiece is loaded, an automatic cycle of microfmishing starts. The automatic cycle of microfmishing comprises a first operational cycle, a second operational cycle and a third operational cycle.
In the first operational cycle, the pusher assembly (50) advances for pushing the workpiece to ensure correct location of the workpiece. As soon as the headstock assembly (20) retracts to an original position, the headstock assembly (20) starts rotation thereby causing rotation of the workpiece. The microfmishing attachment (120) approaches to position where polishing operation's done.
In the second operational cycle, the film of backed abrasive moves over the ring ($6) guided by the plurality of rollers (94). The non-metallic insert (88) ensures that the film of backed abrasives moves in point contact with the workpiece. This arrangement advantageously ensures that the film of backed abrasives is positioned in contact with the internal surface of the workpiece to be microfmished resulting in a superior quality internal surface finish. In a next step, the cylinder (100) of the microfmishing attachment (110) moves down to create the tightness in the film of backed abrasives. In further step, a motorized shaft (not shown) winds the film of backed abrasives and maintains constant tension via the clutch. The workpiece then advances with the headstock assembly (20) towards position where polishing

operation is to be carried out.
In the third operational cycle, the microfinishing attachment (120) again advances towards the workpiece. In next step, after completion of polishing, the microfinishing attachment (120) retracts while retracting the film of backed abrasives is indexed thereby completing the automatic cycle of microfinishing. In next step, a door (130) of the machine (200) is opened and the workpiece is unloaded manually.
The method (300) of the present invention is used to finish internal surface of the workpiece (22) for example, a synchrocone. However, it is understood that the method (300) can be used to microfmish any workpiece having internal taper surface.
Advantages of the present invention
1. The machine (200) and the method (300) enable finishing of internal diameters using the film of backed abrasives.
2. The machine (200) and the method (300) utilize microfinishing attachments with additional tooling for microfinishing internal diameters for example, for internal finishing of synchrocones.
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the

claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.

We Claim:
1. A machine for finishing an internal surface using a film of backed abrasives, the machine having a base (10), a headstock assembly (20), a slide assembly (30), a cross slide assembly (40), a pusher assembly (50), a coolant system (60), a pneumatic system (70), a lubrication system (80) and a microfmishing attachment (120) characterized in that the microfmishing attachment (120) comprising:
a bracket (82) positioned on the cross slide assembly (40);
a frame (84) positioned on an extended side of the bracket (82);
a cylinder (100) secured on a top surface of the frame (84);
a plurality of rollers (94) mounted on the bracket (82) and adapted for guiding the film of backed abrasives;
an indexing unit (98) adapted for creating a slack and pulling the film of backed abrasives;
an oscillation assembly (96) mounted on the indexing unit (98) and used to oscillate the plurality of rollers (94); and
a shoe assembly (92) attached at a side of the bracket (82), the shoe assembly (92) having
• a ring (86) adapted for passing the film of backed abrasives thereon,
• a non-metallic insert (88) positioned on the ring (86) for ensuring movement of the film of backed abrasives in point contact with a workpiece to be microfinished, and
• a plurality of clips (90) mounting the shoe assembly (92) on to the bracket (82),
wherein, the cylinder (100) and the indexing unit (98) create a slack so that the film of backed abrasives is pulled with zero tension and combination of

the workpiece rotation and oscillation generate a cross hatch pattern required for microfinishing of the internal surfaces.
2. The machine as claimed in claim 1, the ring (86) is a non-rotating stationary ring.
3. The machine as claimed in claim 1, the frame (84) is positioned on the extended side of the bracket (82) using a first set of plurality of cap screws (110) and a dowel pin (112).
4. A method for finishing an internal surface using a film of backed abrasives on a machine having a base, a headstock assembly, a drive assembly, a slide assembly, a cross slide assembly, a pusher assembly, a coolant system, a pneumatic system, a lubrication system and a microfinishing attachment having a frame, a bracket, a cylinder, a plurality of rollers, an oscillation assembly, an indexing unit and a shoe assembly having a ring, a non-metallic insert and a plurality of clips, the method comprising the steps of:
setting the headstock assembly and the pusher assembly at a return position;
loading a workpiece to be microfinished on an internal diameter collet manually; and
starting an automatic cycle of microfinishing, the automatic cycle of microfinishing comprising:
a first operational cycle in which the pusher assembly advances for pushing the workpiece to a correct location and the headstock assembly retracts to an original position and starts rotation thereby causing rotation of the workpiece and the microfinishing attachment approaches to the location where polishing operation is to be carried out:

a second operational cycle in which the film of backed abrasives moves over the ring guided by the plurality of rollers and the cylinder moves down to create the tightness in the film of backed abrasives, the workpiece then advances with the headstock assembly towards a position where polishing operation is to be carried out; and
a third operational cycle in which the microfinishing attachment again advances towards the workpiece thereby completing polishing of the workpiece and retracts thereby completing the automatic cycle of the microfinishing.
5. The method as claimed in claim 4, wherein the cylinder and the indexing unit create a slack so that film of backed abrasives is pulled with zero tension.
6. The method as claimed in claim 4, wherein the non-metallic insert ensures that the film of backed abrasives moves in point contact with the workpiece.