VERTICAL TURNING MACHINE
FIELD OF INVENTION
The present invention in general relates to a vertical turning machine for machining a work piece and in particular to a vertical turning machine and a methodology for machining work piece of substantial diameter with high speed rotation, greater stability and less chatter.
BACKGROUND OF THE INVENTION
Turning machines are well known in the art. Turning machines are used to machine desired metal pieces and shapes from a piece of stock as the stock is turned or rotated at a relatively high speed. A typical turning machine includes a frame, a chuck assembly for holding a piece of stock material in place relative to the machine, a motor and transmission for rotating the chuck assembly and stock material at a desired speed, and a tooling assembly for machining the stock material as it is turned. The tooling assembly generally includes a turret or ram with tool changer unit, which holds a variety of cutting toois and allows for any number of these cutting tools to be interchanged for use in machining a part. Typically, turning machines also include a controller which controls the radial and axial positioning of a cutting tool to produce a part of the desired shape.
One type of turning machine is known as a vertical turning machine as the stock to be machined rotates around a vertical axis as it is machined. Various other types of turning machines are also known.
Turning machines are generally adapted to produce a wide variety of parts, and thus are capable of operating at a wide variety of speeds and of holding a large number of different cutting tools which can be interchanged during the machining process to produce the particular part desired. While conventional turning machines are well adapted to perform a wide variety of machining operations, there are unfortunately several drawbacks with existing turning machines. For example, conventional turning machines require a large quantity of cooling lubricant to be applied to the cutting edge of the cutting tool to remove heat generated during the cutting operation. Otherwise, the heat generated from the cutting operation may cause the turned part, such as an aluminum part, to melt, and may otherwise damage the finish of the machined part. Unfortunately, coolant is expensive, leaves a residue on the finished part and on the turning machine, and cause environmental and health problems. Additionally, as turning machines known in the art are designed to be highly versatile, such machines often require a transmission to adjust the turning speed of the stock material, a turret to house a large number of cutting tools, and various other assemblies to improve the flexibility and versatility of the machine.
As a result of the complexity of such turning machines, difficulties crop up in their maintenance and it involves substantial cost as well. Such machines also tend to wear very quickly. One area of wear in many conventional turning machines is the drive arrangement. The drive arrangement typically includes a motor, a transmission, a belt to engage rotational power to the spindle and chuck assembly, and a number drive belt and pulleys. In such an arrangement, the drive components typically communicate power through a number of drive belts and pulleys which are maintained under significant tension so that the drive power from the motor can be efficiently transferred to the spindle and chuck.
Unfortunately, the transmission, the brake tend to wear significantly as do the bearings of the various rotational items, such as the pulleys, because of the significant amount of belt tension and resultant stresses on the various components. Another drawback of many turning machines is that the rotational speed of the stock material, and thus the speed at which the material can be machined, is limited to speeds below which these machines tend to experience chatter and vibration, which can harm the machine or damage the part being machined.
Additionally, as most of the typical turning machines are designed for small and medium sized components, this cannot fulfill all the requirement of the modern industries.
Accordingly there was a long felt need to provide a vertical turning machine which is adapted to turn the parts of comparatively large size and to machine them at a higher frequency and thus allow the part to be machined faster, as well as to provide a vertical turning machine that requires significantly less cooling lubricants and exhibit significantly low vibration or chatter during the cutting process.
The vertical turning machine in accordance with the present invention meets the aforesaid long felt need.
All through out the specification including the claims, the words "frame", "chuck", "assembly", "motor", "transmission", "tooling", "turret", "drive assembly", "work piece", "driven pulley", "spindle assembly", "turning machine", and "cutting assembly" are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art. Restriction/Limitation if any, referred to in the specification, is solely by way of example and understanding the present invention.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide a vertical turning machine which is adapted to machine a work piece of substantial diameter.
It is a further object of the present invention to provide a vertical turning machine which is adapted to operate with substantially high stability and substantially low chatter.
It is yet another object of the present invention to provide a vertical turning machine which is adapted to operate at a substantially high speed rotation.
It is a further object of the present invention to provide a vertical turning machine which applies substantially lower percentage of cooling lubricants for cooling of the machine.
It is yet another object of the present invention to provide a vertical turning machine which involves simplified construction and low cost of production.
It is a further object of the present invention to provide a method of machining a work piece of substantial diameter with high speed rotation, greater stability and less chatter.
How the foregoing objects are achieved and the other aspects of the present invention will be clear from the following description, which is purely by way of understanding and not by way of any sort of limitation.
SUMMARY OF THE INVENTION
Accordingly the present invention provides a vertical turning machine for machining a work piece with high-speed rotation including a base having a rotary table for rotating a work piece, at least two columns, at least a simply supported cross rail supported by said columns, at least two cross slides adapted to move in a horizontal direction along the guide ways of said rail, at least two rows suspended from the cross slides and adapted to move vertically along a guide way of said cross slide, said machine being provided with ball screws parallel and crossing each other whereby operations are adapted to be done on either side of said table.
In accordance with preferred embodiments of the vertical turning machine of the present invention:
-said base is incorporated with hydrostatic bearings and rotation of said table is facilitated by a motor adapted to run at very high speed and is connected to at least a spindle through a gear and pulley drive arrangement and each said column is mounted at the side of said base with the help of a joining piece, a special structural material being inserted in between said joining piece and said column.
-the spindle is adapted to be turned at at least 2-70 (RPM), whereby heated chip fragments are caused to aviate off the work piece, thereby dissipating heat. This removes the requirement for applying cooling agents for cooling of the machine.
-the drive arrangement includes a flat belt and driven pulleys to efficiently transfer rotational power from said motor to the spindle with minimal wearing of the rotating parts.
-the gear and pulley drive system includes a single belt and said machine is provided with two automatic tool changer units (A.T.C.) for storage of different tools mounted on the ground.
-said gear and pulley drive assembly includes a first driven pulley mounted to said motor and a second driven pulley is mounted to said gear assembly, and a flat belt is provided between an encoder and said spindle assembly.
-each spindle assembly is arranged in a separated housing.
-there is provided a powerful hydraulic braking system adapted to ensure safety of the components of machine, in the event of power failure.
-said turning machine is a turret less vertical turning machine.
The present invention also provides a method for machining a work piece of substantial diameter at high speed rotation with greater stability and less chatter said method including applying a vertical turning machine, said machine including a base having a rotary table for rotating a work piece, at least two columns, at least a simply supported cross rail supported by said columns, at least two cross slides adapted to move in a horizontal direction along the guide ways of said rait, at least two rows suspended from the cross slides and adapted to move vertically along a guide way of said cross slide, said machine being provided with ball screws parallel and crossing each other whereby operations are done on either side of said table.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The nature and scope of the present invention will be better understood from the accompanying drawings, which are by way of illustration of some preferred embodiments and not by way of any sort of limitation. In the accompanying drawings,
Fig 1(a) illustrates the front view of the vertical turning machine according to the present invention;
Fig 1(b) illustrates the side view of the vertical turning machine according to the present invention;
Fig 1(c) illustrates the plan view of the vertical turning machine according to the present invention;
Fig 2 illustrates the cross rail assembly of the vertical turning machine according to the present invention;
Fig 3 schematically illustrates the ram balancing assembly of the vertical turning machine according to the present invention;
Fig 4 schematically illustrates the table base assembly of the vertical turning machine according to the present invention;
Fig 5(a) schematically illustrates the Z-axis kinematics of the vertical turning machine according to the present invention;
Fig 5(b) schematically illustrates the X-axis kinematics of the vertical turning machine according to the present invention.
Fig 6 schematically illustrates the block diagram of the table of the vertical turning machine according to the present invention.
Fig 7 schematically illustrates the ram housing assembly of the vertical turning machine according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The following describes some preferred embodiments of the present invention, which are purely for the sake of understanding the present invention and not by way of any sort of limitation.
The present invention relates generally to an improved vertical turning machine, and more specifically to a new and unique vertical turning machine which is adapted for machining work piece of diameter up to 5000 mm with high-speed rotation, greater stability, less chatter, and which require substantially low amount of cooling lubricants to prevent heat build-up during the machining process.
The vertical turret less lathe includes: A rotary table for rotating a work piece; two column; a simply supported cross rail supported by the columns, two cross slides movable in a horizontal direction along the guide ways of the cross rail, two rams suspended from the cross slide and movable vertically along the guide ways of the cross slides and two automatic tool changer unit loaded with sufficient number of tools. The present invention provides a dedicated vertical turning machine which can machine the large sized components with greater efficiency. Additionally, it can machine the part at either side of the table center.
In the vertical turning machine according to the present invention, the ball screws are located parallel and cross each other in such a manner that machine operations can be performed on either side of the table centre. This can be done with the usual requirements of a high accuracy of finish and a maximum speed of production.
The machine is provided with a powerful hydraulic braking system which ensure the safety of machine components during power failure.
The base is of sufficient mass and area to provide a damping force that facilitates reducing vibrations and harmonics generated by the machine, during machining operation.
The machine includes a motor adapted to run at very high speeds and which is connected to the spindle through a gear and pulley drive arrangement. Preferably, the drive arrangement includes a flat belt and driven pulleys to efficiently transfer rotational power from the motor to the spindle with minimal wear on the rotating parts. Preferably, the machine is designed throughout to minimize the number of moving parts, and thus to reduce the vibration characteristics of the machine.
In accordance with one aspect of the present invention, the machine is dedicated to the manufacture of a limited range of parts and includes a base, a spindle assembly for holding and turning the work piece, a motor, a gear and pulley drive assembly for transferring power from the motor to the spindle assembly, and cutting assembly, the base being of sufficient mass and area to provide a damping force that facilitates reducing vibrations and harmonics generated by the machine, the motor and gear and pulley drive assembly being adapted to rotate the spindle assembly about a vertical axis at a rate wherein chip fragments aviate off of a work piece being machined such that heat generated by the tooling process is removed by the chips which have absorbed the heat.
In accordance with another aspect of the machine, the vertical turning machine includes a base, a spindle assembly mounted to the base for turning a work piece, a motor mounted to the base for powering the spindle assembly, gear and pulley drive assembly for transferring power from the drive motor to the spindle and a cutting assembly for removing material from the work piece, wherein the gear and pulley drive assembly includes a first pulley mounted to the motor and a second mounted to the gear shaft and a flat belt extending between the pulleys,
The vertical turning machine in accordance with the present invention serves the need to machine work piece of large size on a production basis, with the usual requirements of a high accuracy of finish and a maximum speed of production. Such a requirement exists, for example, in the field of production of valves, casings, Cylinder blocks, pistons, piston rings and bearings for internal combustion engines of rails. The present invention also serves the purpose of requirement for a machine tool which is capable of machining work pieces rapidly and accurately to have required non-uniform and large shaped profiles. The machine according to the present invention has the capability of altering the tool position a number of times within a revolution, at high speeds. The method of machining according to the present invention comprises applying the vertical turning machine according to the present invention, whereby the distinct advantages of high speed rotation, use of less coolant, low chatter and greater stability are all achieved simultaneously and that too, at a substantially reasonable cost as compared to what is known in the art.
The preferred embodiments of the present invention are shown in the accompanying figures 1(a), 1(b) and 1(c). The vertical turning machine is designed and adapted as a machine dedicated to the manufacture of comparatively large sized parts with the usual requirements of a high accuracy of finish and a maximum speed of production. As such, the vertical turning machine is preferably designed with a minimal number of moving parts and assemblies and is adapted to turn the workpiece to be machined at a high rate with minimal vibration and chatter. The vertical turning machine includes a base to which is mounted a AC Servo motor, a spindle assembly gears and pulleys. The spindle is adapted to be turned at at least 2-70 (RPM), whereby heated chip fragments are caused to aviate off the work piece, thereby dissipating heat. This removes the requirement for applying cooling agents for cooling of the machine.
The base and columns are preferably connected with the help of a structural member (joining piece) and designed with adequate mass and structural rigidity to provide significant damping to the machine to reduce harmonics and vibrations (i.e., chatter) generated by cutting action of the machine and rotation of the drive motor.
The vertical turning machine according to the present invention gives following operations, namely turning, boring, facing & machine with (Live spindle) 'C' axis gives drilling, tapping, milling operations.
The accompanying figures 1 (a), (b) & c) illustrate the front view, side view and plan view of the vertical turning machine according to the present invention.
The figure 1(a) illustrate the ram(1), cross rail(2), chip conveyor(3), automatic tool charger units(4), table base(5), table(6). The figure 1(b) illustrates the z-axis motor(7), live spindle motor(8), tool holder(9), column(10),ladder(11), shaft less screw conveyor(12) and ram housing (1"). The figure 1(c) illustrate the main spindle motor(7') and control panel(14).
The table(6) is preferably manufactured from high grade cast iron. All the sliding surface of the table are hardened and ground for accurate turning and long service. Jaws are made by alloy steel, ensures better gripping force output even at cutting load. Their stable gripping powers even at higher speed make them ideal for CNC application. The strong hydraulic braking system prevents accidents even at power failure. The present invention has two co!umns(10) casted by high grade cast iron. Each column(10) is mounted at the side of the table base with the help of joining piece. A special structural material is inserted in between the joining piece and column. This helps in establishing a good contact between the columns and joining pieces as well as increases the damping effect. Columns support the cross rail(2). The cross rail carries the cross rail slides. The two automatic tool changer units(4) (A.T.C.) are meant for storage of different tools mounted on the ground.
Hydraulic power pack is used to clamp tool holder(9), for actuating the ram balancing cylinder(16) shown in the accompanying figure 3, for clamping the C- axis, for actuating the chip guard and ATC door. Hydraulic power pack is also useful in applying the additional braking on C-axis which ensure safety against the power failure. Accumulator is given for safety to avoid accident in case of power failure. Atomized lubrication system is used which provides lubrication in pressurized state to all sliding elements like ball screws, Ball screw support bearing etc. Recirculation type oil lubrication provided for spindle assembly. Chip conveyor(3) is designed to maximum chip carrying capacity. Two, shaft less screw conveyors(12) kept at inclined/horizontal position are being used for conveying chips from machine interior to slat type chip conveyor, from which chips finally would be dumped out. Slat type Chip conveyor is very suitable to carry curly chips. It is mounted in front of table base of machine. Coolant tank is of sufficient capacity has three chambers for filtration. Control panel(14) is mounted on right side of machine. Sliding base type pendent box(13) is mounted in front of the machine at side of operation which is designed on the basis of Ergonomics.
The accompanying figure 2 illustrates the cross rail assembly of the vertical turning machine according to the present invention. X axis has high precision, large size ball screw(15) provides good repeatability and fast traverse. This is lubricated by central lubrication system by oil. Ball screw design is of both side supported type facilitating operation at both ends. Ball screw is driven by gear drive and servo motor(7"). Cross rail slides move in horizontal transverse direction on cross rail guide ways through ball screws ('X' axis) and is driven by servo motor through gear transmission.
The accompanying figure 3 illustrates the ram balancing assembly of the vertical turning machine according to the present invention. This has two rams(1) suspended from the cross slide and movable vertically along the guide ways of the cross slide. For balancing the ram during machining operation a hydraulic cylinder(16) is used. This hydraulic cylinder is pressurized by the hydraulic pump.
This figure also illustrate the spindle motor(8), the z-axis motor(7), the ram housing(V) and the tool holder(9).
The accompanying figure 4 schematically illustrate the table base assembly of the vertical turning machine according to the present invention. The fixture is mounted on the top of the table. The main spindle(19) is driven by spindle motor(7') of adequate power capacities through gear and pulley drive assembly. The table is stopped dynamically to bring it to a standstill at an oriented position. This figure also illustrate the table base(5), the gear rim(20), the hydrostatic bearing (17), the gear mechanism(16), the spindle housing(20) and the flat belt(18). The table base(5) is incorporated with hydrostatic bearings(17) replace the previously used mechanical bearings. Hydrostatic bearings are externally pressurized oil bearings, where the pressurization is done by a pump. These hydrostatic bearings are well suited for high load, high precision applications whereas, ordinary ball bearings have short life, high noise and vibration. The drive arrangement in brief, includes a flat belt and driven pulleys to efficiently transfer rotational power from the motor to the spindle with minimal wearing of the rotating parts. It should be understood to persons skilled in the art that there can be more than one spindle and spindle assembly and each spindle assembly is preferably arranged in a separated housing(20).
The accompanying figure 5 (a) illustrate schematically the drive mechanism for Z axis, wherein an AC servomotor(7) is coupled through gear transmission to precision ball screw(15'). It is the gear drive to ball screw which results higher rapid travel for Z axis. This figure also illustrate the gear mechanism(16") and pinion(21).
The accompanying figure 5 (b) illustrates schematically the drive mechanism for X axis, wherein an AC servomotor(7") is coupled through gear transmission to precision ball screw(15). It is the gear drive to ball screw which results higher rapid travel for X axis. This figure also illustrate the pinion(21) and the gear mechanism(16).
The accompanying figure 6 illustrates schematically the table speed block diagram of the vertical turning machine according to the present invention. The rotary movement to work piece is achieved by servomotor(8), flat belt{18), gear and pulley drive mechanism. This figure shows the driven pulley(22) and motor pulley(22') separated by flat belt(18). It also illustrates the thrust bearing (17), the gear rim(20) and the pinion(21). In brief, the gear and pulley drive assembly includes a first driven pulley mounted to the motor and a second driven pulley mounted to the gear assembly, the flat belt being provided between an encoder and the spindle assembly.
The accompanying figure 7 illustrates schematically the ram housing assembly of the vertical turning machine according to the present invention. As already illustrated in the accompanying figure 3 it also shows two rams(1) suspended from the cross rail slide and movable vertically along the guide ways of the cross rail slides. This figure also illustrates the ram housing(l'), the tool holder(9), the spindle motor(8) and the z-axis motor(8).
The present invention discloses an advancement over machines of the prior art by providing a mechanically stiffer machine exhibiting improved dynamic characteristics as disclosed hereinbefore and defined in the appended claims.
The machine in accordance with the present invention is also more reliable than the machines of the prior art. The method of machining work pieces of substantial diameter by applying the machine in accordance with the present
invention thus also yields stupendous results hitherto unknown and not conceived and furthermore, as discussed hereinbefore, the cost involvement is also substantially low having regard to the simplified construction of the machine.
This technical advancement and economic significance was hitherto unknown and not conceived by persons skilled in the art.
The present invention has been described with referance to some drawings and preferred embodiments, purely for the sake of understanding and not by way of any limitation and the present invention includes all legitimate developments within the slope of what has been described herein before and claimed in the appended claims.
We Claim :
1. A vertical turning machine for machining a work piece with high-speed rotation including a base having a rotary table for rotating a work piece, at least two columns, at least a simply supported cross rail supported by said columns, at least two cross slides adapted to move in a horizontal direction along the guide ways of said rail, at least two rows suspended from the cross slides and adapted to move vertically along a guide way of said cross slide, said machine being provided with ball screws parallel and crossing each other whereby operations are adapted to be done on either side of said table.
2. The vertical turning machine as claimed in claim 1 wherein said base is incorporated with hydrostatic bearings and rotation of said table is facilitated by a motor adapted to run at very high speed and is connected to at least a spindle through a gear and pulley drive arrangement and each said column is mounted at the side of said base with the help of a joining piece, a special structural material being inserted in between said joining piece and said column.
3. The vertical turning machine as claimed in claim 2, wherein the spindle is adapted to be turned at at least 2-70 (RPM), whereby heated chip fragments are caused to aviate off the work piece, thereby dissipating heat.
4. The vertical turning machine as claimed in claim 2, wherein the drive arrangement includes a flat belt and driven pulleys to efficiently transfer rotational power from said motor to the spindle with minimal wearing of the rotating parts.
5. The vertical turning machine as claimed in claim 4 wherein the gear and pulley drive system includes a single belt and said machine is provided with two automatic tool changer units (A.T.C.) for storage of different tools mounted on the ground.
6. The vertical turning machine as claimed in claim 5 wherein said gear and pulley drive assembly includes a first driven pulley mounted to said motor and a second driven pulley is mounted to said gear assembly, and a flat belt is provided between an encoder and said spindle assembly.
7. The vertical turning machine as claimed in claim 6 wherein each spindle assembly is arranged in a separated housing.
8. The vertical turning machine as claimed in any preceding claim, wherein there is provided a powerful hydraulic braking system adapted to ensure safety of the components of machine, in the event of power failure.
9. The vertical turning machine as claimed in any preceding claim, wherein said turning machine is a turret less vertical turning machine.
10. A method for machining a work piece of substantial diameter at high speed rotation with greater stability and less chatter, said method including applying a vertical turning machine, said machine including a base having a rotary table for rotating a work piece, at least two columns, at least a simply supported cross rail supported by said columns, at least two cross slides adapted to move in a horizontal direction along the guide ways of said rail, at least two rows suspended from the cross slides and adapted to move vertically along a guide way of said cross slide, said machine being provided with ball screws parallel and crossing each other whereby operations are done on either side of said table.