FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Method of Slacking and Tensioning of Film for Microfinishing Machine"
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.

Method of Slacking and Tensioning of Film for Microfinishing Machine
Field of the invention
The present invention relates to a metal surface finishing and more particularly, to a method of slacking and tensioning of a film for a microfinishing machine.
Background of the invention
Microfinishing is a process of abrasion of a workpiece which has been previously rough ground or turned using an abrasive film. During the process, the film needs to be indexed. Indexing is done by tightening/providing tension in the film. This is achieved by retracting a microfinishing arm-pack and moving it backward to tighten the film. Once the film is indexed, the microfinishing arm-pack moves forward and opens to make the film loose again.
Existing methods involve using an arm slide or a hydraulic/pneumatic slide that undergoes forward/backward motion for retracting the microfinishing arm. These methods require 2-3 seconds for retraction and backward movement and few more seconds for moving the slide forward after indexing the film thereby wasting a total of 5-6 seconds of time every time the film is indexed.
Accordingly, there a need to provide a method of slacking and tensioning of a film for a microfinishing machine that overcomes the drawbacks of the prior art.
Object of the invention
An object of the present invention is to provide a slacking and tensioning

mechanism for a micro finishing machine that enables film indexing without retracting a microfinishing arm-pack and reduces the cycle time of the microfinishing machine.
Summary of the invention
Accordingly, the present invention provides a method of slacking and tensioning of a film for a microfinishing machine. The microfinishing machine comprises a roll of film, a plurality of rollers, an arm-pack and a slack and indexing unit. The slack and indexing unit comprises a pneumatic cylinder, an indexer and a bin.The arm-pack includes a plurality of microfinishing arm units. Each arm of the plurality of microfinishing arm units includes an upper arm and a lower arm. The method comprises passing the roll of film to the plurality of rollers and directing the roll of film towards the arm-pack. The method further involves performing a microfinishing operation wherein the upper arm and the lower arm get closed. Furthermore, the method involves removing the slack in a used film with the slacker positioned in an upward position and indexing the film with motion of the indexer. In next step, the method involves moving the slacker to a downward position to generate the slack in the film. At the start of the method, the microfinishing operation is set in an automatic mode and from the arm-pack, the film is guided by the plurality of rollers towards the slacker and the indexer and the used film is carried to the bin by the indexer via a film path.
Brief description of the drawings
Figure 1 is a partial view of a microfinishing machine showing a microfinishing of a work piece, in accordance with the present invention;

Figure 2 illustrates a film slack and indexing unit of the microfinishing machine of figure 1; and
Figure 3 shows a flowchart for a method of slacking and tensioning a roll of film, in accordance with the present invention.
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art. techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention provides an innovative method for indexing of a film while a microfinishing arm unit is in forward position. The method does not require retraction of a microfinishing arm-pack and generation of the slack-tension effect. as a result saves considerable amount of cycle time.
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, a partial view of a microfinishing machine (100) for microfinishing of a workpiece (150) in accordance with the present invention is shown. The microfinishing machine (100) comprises a roll of film (10), an arm-pack (20), a plurality of rollers (30) and a slack and indexing unit (40). In an embodiment, the roll of film (10) is an abrasive film.

The arm-pack (20) includes a plurality of microfinishing arm units (not numbered). Each arm of the plurality of microfinishing arm units includes an upper arm (24) and a lower arm (28). Typically, the microfinishing machine (100) has more than two main journal arms and more than two pin journal arms.
The arms (24, 28) close around a diameter of the workpiece (150) to be microfinished like two halves. The abrasive film (10) is held in between the arms (24, 28) and the diameter of the workpiece (150) to be microfinished. The closing of the arms (24, 28) requires a slack in the film (10).
The slack and indexing unit (40) comprises a pneumatic cylinder/slacker (32) (hereinafter "the slacker (32)"), an indexer (34) and a bin (36). After microfinishing of the workpiece (150), a used film (50) is carried to the bin (36) by the indexer (34) via a film path (60). The slacker (32) moves upward and downward to create and remove the slack in the roll of the film (10).
Referring now to figure 3, a flowchart of a method (300) of slacking and tensioning of a film for microfinishing in accordance with the present invention is shown. Specifically, the method (300) is described in conjunction with the microfinishing machine (100).
The method (300) starts at step (210). At start the microfinishing machine (100) is set in an automatic mode. The roll of film (10) is routed through a film layout (not numbered). At step (220), the method (300) involves passing the roll of film (10) to the plurality of rollers (30). Then the film (10) is directed towards the arm-pack (20). From the arm-pack (20), the film (10) is then guided by the plurality of rollers (30) towards the slacker (32) and the indexer (34). The used film (50) is then carried

to the bin (36) by the indexer (34) via the film path (60). In this step, the film (50) is in a slack condition.
At step (230), the method (300) involves performing a microfinishing operation wherein the arms (24, 28) get closed. Once the microfinishing of the workpiece (150) is carried out the arms (24, 28) get opened.
At step (240), the method (300) involves removing the slack in the used film (50) with the slacker (32) positioned in an upward position.
At step (250), the method (300) involves indexing the film (50) with motion of the indexer (34). Indexing is done if the film (50) is tight and when the slack is removed. Once the indexing is done, the used film (50) is then carried to the bin (36).
At step (260), the method (300) involves moving the slacker (32) to a downward position to generate the slack in the film (50).
At step (270) the method (300) ends and the plurality of microfinishing arm units become ready for next microfinishing operation.
Advantages of the present invention
1. The method (300) saves cycle time of the microfinishing by up to 20-30% in a typical microfinishing machine.
2. The method (300) saves energy in moving the arm-pack (20) forward and backward repeatedly thereby causing reducing wear and tear to the microfinishing machine (100).

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 method of slacking and tensioning of a film for a microfinishing machine, the microfinishing machine having a roll of film, a plurality of rollers, an arm-pack and a slack and indexing unit, the arm-pack having a plurality of microfinishing arm units, each arm of the plurality of microfinishing arm units includes an upper arm and a lower arm, the slack and indexing unit having a slacker, an indexer and a bin, the method comprising the steps of:
passing the roll of film to the plurality of rollers and directing the roll of film towards the arm-pack;
performing a microfinishing operation, wherein the upper arm and the lower arm get closed;
removing the slack in a used film with the slacker positioned in an upward position;
indexing the film with motion of the indexer; and
moving the slacker to a downward position to generate the slack in the film,
wherein, at the start, the microfinishing operation is set in an automatic mode and from the arm-pack, the film is guided by the plurality of rollers towards the slacker and the indexer and the used film is carried to the bin by the indexer via a film path.