FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Machine Tool Attachment


APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTOR
Mr. Surendra Datar an Indian national
of TATA MOTORS LIMITED an Indian company
Having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in
which it is to be performed


FIELD OF INVENTION
This invention relates to machine tools in general and more particularly this relates to machine tool attachment that can be used for flat machining operations on vertical and horizontal CNC machines.
BACKGROUND OF INVENTION
Standard vertical or horizontal CNC machines do not have a mechanism of tilting the cutter spindle. During machining the milling cutter has to pass completely on the part on which flats are to be milled and in doing so, the rear portion of the cutter comes in contact with already machined surface which leads to back cut.
This back cut leads to
1) Rubbing of the edges on the machined portion thus lowering the efficiency or potential of the cutting edges.
2) Rougher surface because of re cutting
3) Additional time spent to make the cutter pass completely on the part to be machined.
Said drawbacks can be eliminated by using special purpose milling machine engaged for making flat surface wherein the spindle is tilted slightly such that back cut is eliminated.
OBJECTS OF INVENTION
Main object of this invention is to provide Machine tool attachment which can avoid back cut on machined surfaces during machining.
Yet another object of this invention is to provide Machine tool attachment which can be easily attachable with existing CNC machines.
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Yet another object of this invention is to provide Machine tool attachment which is simple in construction and cost effective.
BRIEF DESCRIPTION OF INVENTION
Machine tool attachment in accordance with this invention basically comprises of driving unit, cutter mounting unit, housing unit and stopper unit. Wherein one end of said driving unit is adapted to mount on machine tool and other end is mounted on said housing unit. Said cutter mounting unit is also mounted on said housing unit in such a way that said driving unit and said cutter mounting unit are connected to each other to transfer the drive power. Said cutter mounting unit is used to mount the cutter unit. Said housing unit is also provided with stopper unit to prevent its movement.
During operation, the machine tool attachment with cutter unit mounted therein which is tilted appropriately to create the spindle tilt effect.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 illustrates sectional view of machine tool attachment in accordance with present
invention.
Fig. 2 illustrates front view of machine tool attachment
Fig.3 illustrates exploded view of split type housing unit along with stopper unit
Fig.4 illustrates isometric view of integral type housing unit along with stopper unit
Fig.5 illustrates cutter mounting unit and driving unit used in this invention
Fig.6 illustrates further embodiments of driving units
DETAILED DESCRIPTION OF INVENTION
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Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,
Referring to figures 1 to 6
Machine tool attachment in accordance with this invention basically comprises of driving unit (6), cutter mounting unit (2), housing unit (8) and stopper unit (7). Wherein one end of said driving unit (6) is adapted to mount on machine tool and other end is mounted on said housing (8). Said cutter mounting unit (2) is also mounted on said housing in such a
way that said driving unit (6) and said cutter mounting unit (2) are connected to each other to transfer the drive power. Said cutter mounting unit (2) is used to mount the cutter unit (1). Said housing unit (8) is also provided with stopper unit (7) to prevent its movement.
During operation the machine tool attachment with cutter unit mounted therein which is tilted appropriately to create the spindle tilt effect.
Said machine tool attachment has three main parts
1) Housing unit (8): Split or Integral
2) Driving spindle (6) with suitable matching taper with machine tool.
3) Cutter Mounting plate or driven spindle (2)
1) Housing:
Referring to figure 1 and 3, cutter mounting unit (2) is supported on housing (8) through bearings (3,5) and is held in its position by means of circlip (10). Said housing is either integrated one or made in two pieces, having a main body (8a) and a cover (8b). Said housing is provided with stopper rod (7) and is fastened at the bottom (14) or at side (15) of said housing (8). In case of housing made in two pieces said cover (8b) is provided on said main body (8a). Said main body is provided with
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desired taper angle (a )preferably 0.03mm in 250mm. This taper on the main body can be ground or fine milled. The cover is provided with provision (12) to accommodate cutter mounting unit and is connected to said main body through fasteners. In order to assist for proper assembly and dismantling of cover to said main body whenever desired dowel pins (13) are used. Said main body (8a) is provided with provision (16) to accommodate driving spindle unit.
In case of integral housing the top portion will have an inclined bore with a desired inclination preferably of 0.007 degrees and will be oriented such that the axis of the bore will have inclination towards the stopper rod side.
2) Driver: Spindle with matching taper to suit machine tool: This will act as a driver and will have a taper to suit the machine on which the attachment will be mounted. It can be an ISO taper or HSK/BT version or any other. This will also have a bearing diameter and circlip groove to keep it in position when assembled in the housing. The other end of the spindle will have provision to take an element of Oldhams coupling (4) or two half meshing (6a,6b)or slot and tenon drive (6a'.6b') or simply driving pin placed in position by a split pin (6a",6b"). A finite gap in the driver and driven end will not matter in operation because it is a positive drive and once in rotation will continue to be in contact. A rubber /Teflon type material can be filled in if the gap is large. Close fitment however will be sufficient because in finish milling the cutting loads will be light. This basic design can also be improvised for rough milling of parts.
3) Cutter Mounting plate : This plate acts as a driven spindle. Said plate is having a provision to accommodate desired cutter at one end and other end is provided with a means for transfer of motion. Preferably said plate is provided with a projection (19) at its centre to accommodate the cutter (1). Said plate is also provided with tenons (16) for driving and threaded holes (20) for clamping the cutter. The Pitch Circle Diameter (PCD) for clamping holes and size of tenons will be as per the cutter diameter intended for use. The cutter mounting plate (2) is provided with a bearing diameter and circlip groove (17) to retain it in the housing after it is mounted. The bottom
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portion of the mounting plate is machined to have an Oldhams coupling or two half meshing or slot and tenon drive or simply driving pin placed in position by a split pin.
Said machine tool attachment is obtained by assembling Cutter Mounting plate (2) and driving spindle (6) in said housing and retained there using circlips (10).
As shown in figure- 1 driving spindle (6) and driven spindle (2) are mounted on the housing (8) duly supported by bearings (3) and (5). Stopper (7) arrests movements of the housing thereby causing the transfer of drive power from driving spindle to driven spindle. As cutter is mounted on said driven spindle it will be rotated on transfer of drive power from driving spindle to the driven spindle.
Although the attachment will be very useful on a CNC set up involving flat making of cylinder head (block contact face) or cylinder block (head contact face) because the quality norms are very tight, the attachment will be useful on any milling machine where accurate flats are to be made with low surface roughness and flatness value without back cut. The only change will be the taper on spindle 6. Instead of HSK 100 or 63 it can be an ISO taper. Following advantages will accrue particularly in finish milling of flats.
1) Better tool life. Since re contact with the cut part and the rubbing of edges will be absent
2) Quality of cut surface will improve dramatically because there will be no back cut. Contact of the entire cutter will be absent which will lead to reduced forces and therefore flatness and surface finish will be better
3) As soon as the leading edges are out of the part, the cutter can be withdrawn. This will reduce machining time. More saving with larger cutter diameter!
Since all the advantages mentioned above are visible on an SPM which is by far the best way of machining flat parts getting best out of the tool and with minimum time,
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the scheme mentioned above is merely an extension of the proven features of an SPM which does this because of a slight tilt in the spindle, It must be noted that with this attachment, cutter must always enter the part opposite to spindle tilt, similar to SPM.
Although this attachment will be most suited for a CNC machine, with a suitable spindle taper can be used on a GP Milling machine. The only care to be taken will be feed direction. This attachment will function effectively when milling cutter will always enter the part opposite to tilt. Thus back cutting will be absent.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the eauivalents thereof.
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WE CLAIMS:
1. A machine tool attachment comprising
a drive unit and a cutter mounting unit mounted on a housing;
a stopper attached to said housing;
said drive unit and said cutter mounting unit are connected to each other to transfer the drive power; and
said housing provided with a taper angle to enable the cutter unit to be tilted during operation.
2. The machine tool attachment as claimed in claim 1. wherein said housing provided with a taper angle preferably 0.03 mm in 250 mm.
3. The machine tool attachment as claimed in claim 1, wherein said housing includes a main body and a cover.
4. The machine tool attachment as claimed in claim 3, wherein said cover is
provided with a provision to accommodate said cutter mounting unit and is
connected to said main body through fasteners.
5. The machine tool attachment as claimed in claim 3, wherein dowel pins are provided for proper assembly of said main body and cover.
6. The machine tool attachment as claimed in claim 3, wherein said main body is provided with provision to accommodate said drive unit.
7. The machine tool attachment as claimed in claims 1, wherein said housing unit is an integrated unit and a top portion of said integrated housing unit has an inclined bore of preferably 0.007 degrees and will be oriented such that the axis of the bore will have inclination towards the stopper rod side.
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The machine tool attachment as claimed in claim 1, wherein said drive unit and cutter mounting unit are supported on said housing unit through bearings and is held in its position by circlips
The machine tool attachment as claimed in claim 1, wherein said cutter mounting unit is provided with a projection at about its centre to accommodate said cutter unit, tenons for driving and threaded holes for clamping the said cutter unit.
A machine tool attachment substantially as herein described with reference to accompanying drawings.
Dated this 1st day of September 2008

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