DESC:APPARATUS FOR MICROFINISHING AND METHOD THEREFOR

Field of the invention:

The present invention relates to an apparatus and a method for microfinishing of mechanical components, and more particularly to the apparatus and the method for microfinishing of diameters and adjacent faces simultaneously of the mechanical components such as crankshafts and the like.

Background of the invention:

In a prior art, surfaces of any mechanical components are micro-finished using microfinishing, before their installation in a mechanical device. The microfinishing is an abrasion process in which an abrasive belt is brought to stand against the work piece. 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.

Several precision engineering components such as crankshafts and gear pump shafts have adjacent diameters and faces that require microfinishing for functional reasons. The microfinishing of both the surfaces is critical task with specifications on surface finish and geometry parameters.

Current methodology for microfinishing such components use one of the following methods:
1. Microfinishing diameters and faces separately, one after another: This method has a limitation of productivity as the method either increases processing time for doing serially or increases cost of machine for doing parallel in separate stations.
2. Microfinishing of diameters with good quality and guarantee of results, while only polishing thrust faces without consistency of results: This method does not provide good results on microfinishing of the thrust faces.

Accordingly, there exists a need to provide an apparatus and a method for microfinishing of the diameters and the adjacent faces simultaneously of the mechanical components that overcome the abovementioned drawbacks of the prior art.

Objects of the invention:

An object of the present invention is to provide simultaneous microfinishing operation of diameters and adjacent faces of mechanical components.

Another object of the present invention is to ensure consistent microfinishing.

Summary of the invention:

In one aspect, the present invention provides an apparatus for microfinishing of journal diameters and adjacent thrust faces simultaneously of a component. The component is clamped between centers of a headstock and a tailstock and the headstock includes motorized drives for facilitating rotation and oscillation of the component. The apparatus comprises of a contact tooling, a film and a microfinishing arm unit. The contact tooling comprises a plurality of contact surfaces (hereinafter referred as, “the contact surfaces”) for polishing diameters, at least two face polishing inserts (hereinafter referred as, “the face polishing inserts”) and at least two pressurizing ports (hereinafter referred as, “the pressurizing ports”). The contact tooling is built from steel material. The contact surfaces are configured on the contact tooling for microfinishing of the journal diameters of the component. The contact surfaces include any one of materials selected from diamonds, stones, urethane and diamond plated steel configured thereon for microfinishing of the journal diameters of the component. The face polishing inserts are mounted on spring loading. The mounting points of the face polishing inserts are on the face of the contact tooling. The mounting points of the face polishing inserts are connected internally inside the contact tooling to the pressuring ports through internal channels. The pressurizing ports are configured on the contact tooling to facilitate oil/air entry. The face polishing inserts are expandable when pressurized through the pressurizing ports. When the pressurizing ports get air supply, the interconnection to the face polishing inserts carries the air and pushes the face polishing inserts out towards the face to be polished. The face polishing inserts along with the scalloped border of the film are used to polish the thrust faces of the component. The face polishing inserts includes urethane configured thereon to polish the thrust faces of the component. The film includes a flat portion and a scalloped border. The flat portion of the film performs the microfinishing of the journal diameters of the component. The scalloped border of the film is used to polish the thrust faces of the component. The film is a flexible film with backed abrasive. Specifically, the film is typically a microfinishing film made from a polyester film backing with abrasive particles on the surface. The film is mounted on the contact tooling and adjusted between the contact tooling and the component.

In another aspect, the present invention provides a method for microfinishing of journal diameters and adjacent thrust faces simultaneously of the component. The method is described in conjunction with the apparatus. At first step, the component is clamped between the centers of the headstock and the tailstock, wherein the headstock includes motorized drives for facilitating rotation and oscillation of the component. Further, the microfinishing arm unit closes the arm around the diameter of the component, thereby ensuring the diameter of the component is in contact with the film and the contact tooling properly. At next step, the method involves activating the pressurizing ports with the air supply through the internal channels, thereby expanding the face polishing inserts to ensure proper contact with the faces of the component. Thereinafter, the component is rotated and oscillated for creating the surface finish required on the diameter and the surface finish on the face due to abrasive action between the film and the surface of the component. After set period of time, the rotation/oscillation of the component is stopped. Then, the pressurizing ports are deactivated by discontinuing the air supply. Further, the microfinishing arm unit is opened and the component is removed.

Brief description of the drawings:

Figure 1 shows schematic views of an apparatus for microfinishing, in accordance with the present invention;

Figure 2 shows an exploded view of the figure 1; and

Figure 3 shows an exploded view of a contact tooling of the apparatus for the microfinishing, in accordance with the present invention.

Detailed description of the embodiments:

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 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 to 3, an apparatus (100) for microfinishing of journal diameters and adjacent thrust faces simultaneously of a component (10), in accordance with the present invention is shown. In an embodiment, the component (10) can be selected from several precision engineering components including crankshafts, gear pump shafts and the like. In a preferred embodiment, the component (10) includes a crankshaft with thrust faces next to journal diameters that are need to be microfinished. The component (10) is mounted on the apparatus (100) to carry out the simultaneous microfinishing of the thrust faces and the journal diameters of the component (10). The component (10) is clamped between centers of a headstock (not shown) and a tailstock (not shown). The headstock includes motorized drives (not shown) for facilitating rotation and oscillation of the component (10). The apparatus (100) comprises a contact tooling (60), a film (20) and a microfinishing arm unit (not shown).

The contact tooling (60) comprises a plurality of contact surfaces (30) (hereinafter referred as, “the contact surfaces (30)”) for polishing diameters, at least two face polishing inserts (40) (hereinafter referred as, “the face polishing inserts (40)”) and at least two pressurizing ports (50) (hereinafter referred as, “the pressurizing ports (50)”). In an embodiment, the contact tooling (60) is built from steel material. The contact surfaces (30) are configured on the contact tooling (60) for microfinishing of the journal diameters of the component (10). In a specific embodiment, the contact surfaces (30) include any one of materials selected from diamonds, stones, urethane and diamond plated steel configured thereon for microfinishing of the journal diameters of the component (10).

The face polishing inserts (40) are mounted on spring loading (not numbered). The mounting points of the face polishing inserts (40) are on the face of the contact tooling (60). The mounting points of the face polishing inserts (40) are connected internally inside the contact tooling (60) to the pressuring ports (50) through internal channels. In the embodiment, the internal channels are machined holes.

The pressurizing ports (50) are configured on the contact tooling (60) to facilitate oil/air entry. In an embodiment, the face polishing inserts (40) are expandable when pressurized through the pressurizing ports (50). When the pressurizing ports (50) get air supply, the interconnection to the face polishing inserts (40) carries the air and pushes the face polishing inserts (40) out towards the face to be polished. The face polishing inserts (40) along with the scalloped border of the film (20) are used to polish the thrust faces of the component (10). In the embodiment, the face polishing inserts includes urethane configured thereon to polish the thrust faces of the component (10).

The film (20) includes a flat portion (not numbered) and a scalloped border (not numbered). The flat portion of the film (20) performs the microfinishing of the journal diameters of the component (10). The scalloped border of the film (20) is used to polish the thrust faces of the component (10). In the embodiment, the film (20) is a flexible film with backed abrasive. In a preferred embodiment, the film (20) is typically a microfinishing film made from a polyester film backing with abrasive particles on the surface. The film (20) is mounted on the contact tooling (60). Specifically, the film (20) is adjusted between the contact tooling (60) and the component (10).

Again, referring to figures 1 to 3, a method for microfinishing of journal diameters and adjacent thrust faces simultaneously of a component (10), in accordance with the present invention is described. The method is described in conjunction with the apparatus (100).

At first step, the component (10) is clamped between the centers of the headstock and the tailstock, wherein the headstock includes motorized drives for facilitating rotation and oscillation of the component (10). Further, the microfinishing arm unit closes the arm around the diameter of the component (10), thereby ensuring the diameter of the component (10) is in contact with the film (20) and the contact tooling (60) properly.
At next step, the method involves activating the pressurizing ports (50) with the air supply through the internal channels, thereby expanding the face polishing inserts (40) to ensure proper contact with the faces of the component (10).

At further step, the component (10) is rotated and oscillated for creating the surface finish required on the diameter and the surface finish on the face due to abrasive action between the film (20) and the surface of the component (10). After set period of time, the rotation/oscillation of the component is stopped.

Thereinafter, the pressurizing ports (50) are deactivated by discontinuing the air supply. Then, the microfinishing arm unit is opened and the component (10) is removed.

The apparatus (100) was tested on a real crankshaft with requirement for microfinishing of main and pin journals and adjacent faces. The results are provided below wherein Ra indicates arithmetic average roughness.

Results Incoming Surface Finish Output Surface Finish with Normal Tooling Output Surface Finish with Special Tooling Apparatus (100)
Main and Pin Journals Ra 0.6-0.8 microns Ra 0.1 Microns Ra 0.1 Microns
Main and Pin Side Faces Ra 0.8 microns Only Visually polished. Variable finish upto Ra 0.8 microns Ra 0.3 microns

Advantages of the invention:

1. The apparatus (100) and the method ensure consistent results of face polishing.
2. The apparatus (100) facilitates simultaneous microfinishing operation to reduce cycle time.
3. The apparatus (100) leads to minimal cost addition.

The foregoing descriptions of specific embodiments of the present invention have 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, and 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 omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the scope of the claims of the present invention. ,CLAIMS:We Claim:

1. An apparatus (100) for microfinishing of journal diameters and adjacent thrust faces simultaneously of a component (10), wherein the component (10) is clamped between centers of a headstock and a tailstock and the headstock includes motorized drives for facilitating rotation and oscillation of the component (10), the apparatus (100) comprising:
a contact tooling (60) having,
• a plurality of contact surfaces (30) configured thereon for polishing the journal diameters of the component (10),
• at least two face polishing inserts (40) mounted thereon via spring loading, and
• at least two pressurizing ports (50) configured thereon to facilitate oil/air entry, wherein mounting points of the at least two face polishing inserts (40) are interconnected internally inside the contact tooling (60) to the at least two pressurizing ports (50) through internal channels; and
a film (20) mounted on the contact tooling (60) and adjusted between the contact tooling (60) and the component (10), the film (20) having,
• a flat portion to perform the microfinishing of the diameter of the component (10), and
• a scalloped border to polish the thrust faces of the component (10);
a microfinishing arm unit having an arm for closing around journal diameter of the component (10) to be polished, thereby ensuring the diameter of the component (10) is in contact with the film (20) and the contact tooling (60) properly;
wherein, the at least two pressurizing ports (50) is activated with air supply through the internal channels thereby expanding the at least two face polishing inserts (40) out towards face of the component (10) to ensure proper contact and the component (10) is rotated and oscillated for creating the surface finish required on the diameter and the surface finish on the face due to abrasive action between the film (20) and the surface of the component (10) for set period of time.

2. The apparatus (100) as claimed in claim 1, wherein the contact tooling (60) is built from steel material.

3. The apparatus (100) as claimed in claim 1, wherein the contact surfaces (30) include any one of materials selected from diamonds, stones, urethane and diamond plated steel configured thereon for microfinishing the journal diameters of the component (10).

4. The apparatus (100) as claimed in claim 1, wherein the at least two face polishing inserts (40) includes urethane configured thereon to polish the thrust faces of the component (10).

5. The apparatus (100) as claimed in claim 1, wherein the at least two face polishing inserts (40) are expandable once pressurized through the at least two pressurizing ports (50).

6. The apparatus (100) as claimed in claim 1, wherein the film (20) is a flexible film with backed abrasive.

7. The apparatus (100) as claimed in claim 1, wherein the film (20) is typically a microfinishing film made from a polyester film backing with abrasive particles on the surface.

8. A method for microfinishing of journal diameters and adjacent thrust faces simultaneously of a component (10) comprising steps of:
clamping the component (10) between centers of a headstock and a tailstock, wherein the headstock includes motorized drives for facilitating rotation and oscillation of the component (10);
closing an arm of a microfinishing arm unit of an apparatus (100) around the diameter of the component (10) to be polished, thereby ensuring the diameter of the component (10) is in contact with a film (20) of the apparatus (100) and a contact tooling (60) of the apparatus (100) properly;
activating at least two pressurizing ports (50) of the contact tooling (60) with air supply through internal channels configured therein, thereby expanding at least two face polishing inserts (40) of the contact tooling (60) to ensure proper contact with faces of the component (10);
rotating and oscillating the component (10) for creating the surface finish required on the diameter and the surface finish on the face due to abrasive action between the film (20) and the surface of the component (10) to be polished;
ending the rotation/oscillation of the component (10) after set period of time;
deactivating the at least two pressurizing ports (50) by discontinuing the air supply;
opening the microfinishing arm unit; and
removing the component (10).

Dated this 03rd day of August 2017

Madhavi Vajirakar
(Agent for Applicant)
(IN/PA-2337)