Title of Invention

NEW GENERATION CNC MILLING MACHINE

Abstract

This invention relates to a new generation CNC Milling Machine having a novel de-clamping system and a unique dampening system. The unique combination of specifications and features of the CNC Milling Machine of the present invention are highly beneficial to the user especially in the small-scale industrial sector. The novel de- clamping system helps to reduce the activity time and the effort required by the operator. The unique dampening system of the present invention reduces or nullifies the vibrations on the worktable.

Full Text

Field of the invention: This invention relates to a new generation CNC Milling Machine having a novel de-clamping system and a unique dampening system. The unique combination of specifications and features of the CNC Milling Machine of the present invention are highly beneficial to the user, especially in the small-scale industrial sector. Background: In CNC Machines, the operator has to frequently change the cutter used on the milling machine depending on the type of machining operations that are to be performed. Hence, there is a need to design a novel de-clamping system. Another disadvantage is that in a known milling machine, during the process of metal cutting, which is carried out on the work piece on the moving table, certain vibrations are produced. The accuracies and surface finish levels produced on the work piece depend on the severity of these vibrations. To avoid these vibrations or to counter these vibrations, this invention proposes a novel dampening system. Discussion of prior art: With the older methods, the time of the total activity is high and the clamping force achieved is subjective, non-uniform and not fixed in magnitude. The effort involved does not translate to higher assurance on the part of the operator that proper clamping has in fact been achieved, with the operator using both hands to operate two spanners. There are negative consequences on precision and on the useful life of costly components like bearings and spindles due to hammering. In the new clamping system of the present invention, the total activity time is reduced with the clamping force achieved being uniform, fixed and non-subjective. The force is not subjective since it is given by the pre-adjusted spring set. The effort involved is smaller than the older method with greater assurance for the operator with respect to proper clamping. One spanner is operated freeing the operator's other hand to support the tool holder. Impact loads on precision and costly components like bearings and spindles due to hammering, which can reduce their useful life are avoided. Summary of the invention: The following objectives summarize the invention 1. It is an object of the present invention to provide a new generation milling machine with a unique de-clamping and dampening system. 2. A further object of the present invention is to provide a novel de-clamping system, which will help to reduce the activity time and the effort required by the operator. 3. Another object of the present invention is to provide a unique dampening system, which reduces or nullifies the vibrations on the worktable. 4. Yet another object of the present invention is to provide a new generation milling machine, which will include the following facilities:- • Closed loop servo system in three axes; • Milling Head incorporating main spindle driven through a built in gearbox; • Integral machine bed and column for extra rigidity; • Bed itself collects the coolant and acts as a coolant tank; • Electrical cabinet with fixed operator control panel; • Mechanical hand wheel for axes movements; and • Operations done on the CNC/DRO/Manual Modes. Though the features listed above are present in some of the machine either singly or in combination, only this machine has all the above features together in one imit. In addition, for the first time, the following two innovations are developed and incorporated in this machine: • Unique tool de-clamping system; and • Unique dampening system. Brief description of drawings: Fig.l illustrates the new generation milling machine of the present invention; Fig.2 illustrates the tool clamping and de-clamping system of a manual milling machine; Fig.3 illustrates the unique tool de-clamping system of present invention; and Fig.4 illustrates the unique de-clamping system of the present invention. Detailed description of the invention: The machine concept (Ref. Fig.l) is basically a bed type CNC Milling Machine with the X and Y axes movement given to the worktable and Z movement to the Spindle head in the vertical axis. The closed loop servo-system for all 3 axes is the portion marked 1 in Fig. 1. Part 2 represents the milling head incorporating the main spindle driven through the built-in gearbox and the integral bed and column for extra rigidity is represented by numeral 3. The coolant tank 4 integral with bed 3 is in the bottom portion. The electrical cabinet 5 is provided with a fixed operator control panel 6 for operation with CNC/DRO/manual modes. The mechanical hand wheels 7 & 8 are provided for axis movement. Wheel 7 is fixed on a unique dampening system 9. A unique tool clamping system 10 is provided in the top portion of the milling machine. Unique Tool de-clamping system: The unique tool clamping and de-clamping system is illustrated in Fig. 2. The machine main spindle 11 holds the tool holder 12 with a cutter for the machining operation. The operator has to de-clamp and remove from the spindle, the tool that has completed the required machining operation and clamp a fresh tool holder required for the next machining operation. In other words, the operator has to frequently change the cutter used on the milling machine depending on the type of machining operation he wants to perform. The operator does this activity through a series of sub actions m the known conventional manual milling machines, which take considerable effort and come with uncertainties. The new unique tool de-clamping system solves all the disadvantages of this conventional method of operation while maintaining low cost for the mechanism. Existing conventional method: The following steps are incorporated in the conventional milling method: 1. The operator holds the clamping nut 13 (Fig. 2) with a suitable spanner with his left hand and then loosens the drawbar 14 with another spanner with his right hand. 2. Frequently he has to resort to administering jerky blows with a plastic hammer onto the spanner on the clamping nut 13 in order to initially loosen it from the clamping force. 3. He gives a blow with a plastic hammer onto the top of the drawbar 14 m order to push and release the holder from the female spindle taper. 4. He loosens the drawbar 14 with a spanner while holding the clamping nut with another spanner. 5. He holds the tool holder with one hand to prevent it from falling onto the machine table when he rotates the drawbar 14 completely to disengage from the tool holder 12. For clamping the new tool holder onto the Spindle, the following steps are followed in the conventional method: 1. The tool holder is inserted onto the spindle and the clamp threads 15 of the draw bar 14 are engaged. 2. The draw bar 14 is tightened with a spanner fully until more thread engagement is realized. 3. The lock nut 13 is tightened with a bigger spanner. 4. The draw bar is held with the smaller spanner and the clamp nut is tightened with the bigger spanner more firmly until the desired clamping force is felt to be achieved. 5. A few jerky blows are administered with plastic hammer onto the bigger spanner to achieve better clamping force. In the above procedure, the time of the total activity is high and the clamping force achieved is subjective, non-uniform and not fixed in magnitude. The effort involved does not translate to higher assurance on the part of the operator that proper clamping has in fact been achieved, with the operator using both hands to operate two spanners. There are negative consequences on precision and the useful life of costly components like bearings and spindles due to hammering. In the new clamping system of the present invention, the total activity time is reduced with the clamping force achieved being uniform, fixed and non-subjective. The force is not subjective since it is given by the pre-adjusted spring set. The effort involved is smaller than the older method with greater assurance for the operator with respect to proper clamping. One spanner is operated freeing the operator's other hand to support the tool holder. Impact loads on precision and costly components like bearings and spindle due to hammering, which can reduce their useful life are avoided. As shown in Fig. 3, the clamping system consists of a set of Disc springs 16 held on a Draw bar 14, which also carries a set of hardened clamping balls 17. A pre adjusted mechanical force due the compression of the disc springs is applied through the balls onto the taper of the Pull stud 18 thereby pulling it upwards. This pulls the tool holder 19 to since it is attached to the pull stud 18 against the taper 20 of the machine spindle 21. Thus, the tool holder is clamped onto the spindle of the machine. The new De-clamp Subassembly 22 is situated on the Housing 23, which is stationary. It consists of a De-clamp Housing 23 in which a de-clamp plug 24 is made to move up and down. This is done by means of the de-clamp screw 25. The de-clamp screw can be rotated but it is prevented from coming out in the axial direction by means of a set collar 26 pinned onto the screw. Hence, when the de-clamp screw is rotated, the de-clamp plug moves downwards whether the screw is rotated clockwise or anti-clockwise. The de-clamp plug has two distinct positions marked by the spring loaded indent ball 27 engaging with the two indent notches in the plug. To the de-clamp plug, a pin 28 is attached which when moving along with the plug actuates a limit switch 29. The Plug is prevented from rotating by means of a plate 30 engaging with a flat surface of the Plug (see sectional view A-A). Because of this, whenever the de-clamp screw is rotated, the Plug moves in the axial direction. The springs 16 are housed in 31. Operation: When the machine is in operation, the tool holder is in a clamped condition as shown in the Fig. 3 and the machine spindle rotates during the machining operation. The de-clamp sub assembly is also shown for this condition. The gap (A) between the de-clamp plug which is in the upper position and the draw bar, is essential to prevent the rubbing of the plug face and the spindle and ensured since the draw bar rotates along with the spindle. The de-clamp sub assembly including the de-clamp plug is stationary. In this condition, the disc spring set has the required pre-tension to exert the appropriate clamping force onto the tool holder through the clamp balls. When the tool holder has to be de-clamped, switching off the motor driving the spindle first stops the machine's main spindle. Then the de-clamp screw 25 is rotated coimter clockwise i.e. loosened, thereby making the de-clamp plug 24 move downwards. The plug travels over the gap and then touches the draw bar. Subsequent axial movement of the plug through the rotation of the de-clamp screw, pushes the draw bar down. Consequently, the balls at the end of the drawbar release the pressure on the pull stud. They also move radially outwards once they come out of the restricting bore through this axially downward motion of the draw bar. Thus the tool holder is de-clamped when loosening the de-clamp screw mounted on the top of the milling head presses the disc springs down. For clamping the fresh tool holder which is inserted into the spindle taper bore, the de-clamp screw is rotated clockwise. When this is done, the de-clamp plug travels upwards, thereby allowing the draw bar to be pushed upwards by the disc spring force. The clockwise rotation of the de-clamp screw is continued to allow the draw bar to completely move upwards drawing the tool holder taper to engage completely with the spindle taper and the spring set to exert the clamping force onto the tool holder through clamp balls. The clockwise rotation of the de-clamp screw is still continued to move the de-clamp plug further up making it to leave the contact with the draw bar. When the indent ball reaches the top indent notch position, the desired safe operating gap between the de-clamp plug and the rotatmg drawbar is achieved. This is additionally confirmed by the limit switch which gets activated by the pm attached to the de-clamp plug and only then can the spindle motor can be switched on to rotate. This is a safety interlock. Distinct positions are provided with ball indents to give the operator a clear indication of the clamp/de-clamp status. The tightening and loosening of the de-clamp screw mechanism is carried out with single spanner. When the operator wants to clamp a tool holder, his normal mental expectation/reaction is to tighten, i.e. clockwise rotation of, the top screw and when he wants to de-clamp the tool holder he expects to loosen, i.e. counter clockwise rotation, of the screw. In order to satisfactorily meet the normal expectation or reaction of the operators, the thread of the de-clamp screw and the de-clamp plug assembly are deliberately made as left hand threads. The ball gripping and the spring loaded clamping Rod sub assembly is similar to the ones generally used in more expensive CNC Machining centers. But this sub assembly in conjunction with the new simple hand operated screw mechanism to actuate the disc spring set which is described above is unique and made available for the first time for manual operation. Unique Dampening System: The milling machines usually have long worktables. Likewise this machine too has a long worktable. Referring to Fig. 4, the length of the table (32) for this machine is large at 1350 mm in relation to its small width of 315 mm. Hence the table overhanging projection extends considerably outwards, considering the supporting length of the guides. Certain vibrations are produced on the table whose severity impacts the accuracies and surface finish levels produced on the work piece. The severity of vibrations is usually high because of the overhanging nature of the table. The unique dampening system consists of carefully selected auxiliary weight mass 33 mounted attached to the overhanging end of the table. However, the fixing of this mass to the table is not direct but through a set of intermediate isolating rubber pads 34. This arrangement is done at two places - the first (L) at the left end of the table and the second (R), at the right end of the table. The milling process, which by its very nature is an intermittent process of metal cutting, is carried out on the work piece on the moving table. When the table vibrates, it induces vibrations of the auxiliary masses attached at either end. However, the induced vibrations are lagging behind in time frame because of the intermediary rubber plugs. Hence, in the unique dampening System, the auxiliary masses vibrate counter to the basic vibrations of the table, i.e. with a time lag, thereby reducing or nullifying the main vibrations. This in turn improves accuracies and surface fmish on the finish milled surfaces of the components machined on the machine. We Claim: 1. A new generation milling machine comprising: a. closed loop servo system in three axes; b. milling Head incorporating main spindle driven through built in gearbox; c. integral machine bed and columnm for extra rigidity; d. said bed comprising provision to collect the coolant and which also acts as a coolant tank; e. electrical cabinet with fixed operator control panel; f. mechanical hand wheel for axes movements; g. a unique tool clamping and de-clamping system; and h. a unique dampening system, said machine operation being carried out on the CNC/DRO/Manual Modes. 2. A de-clamping system for the new generation milling machine comprising: a) de-clamping means which is a movable between two predetermined points; b) means to enable movement of the de-clamping means; c) means for engaging the de-clamping means at the pre-deterrmined location/point; d) a safety interlocking means to confirm the de-clamping/clamping operation; e) means to prevent the rotation of the de-clamping means; and f) a housing to house all the above. 3. A de-clamping system as claimed in claim 2, wherein the de-clamping means is a movable plug 24; the motion being enabled by a de-clamp screw 25. 4. A de-clamping system as claimed in claim 3, wherein the screw 25 is provided with a set collar pinned on to the housing wherein the de-clamping means is placed to avoid axial movement of the screw. 5. A de-clamping system as claimed in any one of claims 2 to 4, wherein the movable plug is provided with two indent notches which is engaged by the spring loaded indent ball provided at the pre-determmed points. 6. A de-clamping system as claimed in any one of claims 2 to 4, wherein the interlocking means comprises of a pin along with a limit switch, the said switch being actuated by the said pin. 7. A clamping system for the new generation milling machine, comprising a clamping draw bar 14, holding a set of disc springs 16 and a set of hardened clamping balls 17, and a pull stud 18 attached to the tool holder 19 which is clamped to the machine spindle 21. 8. A unique dampening system for the new generation Milling Machine comprising of an auxiliary weight mass 33 mounted on the work table 32 through a set of intermediate isolating rubber pads. 9. A imique dampening system as claimed in claim b, wherein the auxiliary weights mass is provided on both the sides of the table.

Documents:

1289-che-2004 abstract duplicate.pdf

1289-che-2004 abstract.pdf

1289-che-2004 claims duplicate.pdf

1289-che-2004 claims granted.pdf

1289-che-2004 description (complete) duplicate.pdf

1289-che-2004 description (complete) granted.pdf

1289-che-2004 drawings duplicate.pdf

1289-che-2004 drawings.pdf

1289-che-2004 form 3.pdf

1289-che-2004-abstract.pdf

1289-che-2004-claims.pdf

1289-che-2004-correspondnece-others.pdf

1289-che-2004-correspondnece-po.pdf

1289-che-2004-description(complete).pdf

1289-che-2004-description(provisional).pdf

1289-che-2004-drawings.pdf

1289-che-2004-form 1.pdf

1289-che-2004-form 18.pdf

1289-che-2004-form 26.pdf

1289-che-2004-form 5.pdf