Patent Application
20140202293
This invention relates to a dampening adapter for mounting a cutting tool onto a machine turret to reduce vibration when the cutting tool engages a work piece, and a method of using the dampening adapter.
From time to time, machine shops with various types of manual and/or numerically controlled cutting machines, such as lathes, boring machines, grinding machines, milling cutters, drills, eta are asked to machine a work piece having a surface which is hard to reach or a hole which is relatively deep. This difficulty may be created by a work piece having an elongated length that needs a deep bore machined therein, or because the tool holder in the machine has an external diameter that is too large, or because the support arm for the tool is too short.
In these situations, a tool extender is required which can position the cutting tool away from the machine turret and adjacent to a surface of the work piece or into a bore formed in the work piece. The extender is usually secured to the machine turret in a cantilever fashion. A cutting tool, having a carbide, diamond or some other hardened tip, is securely mounted to the free end of the cantilevered extender and therefore projects well beyond the fulcrum point. As the cutting tool engages a work piece, vibrations and/or flexing forces are created which are transmitted back through the extender into the machine turret. If these vibrations or flexing forces become too large, the cutting tip or cutting tool can break or damage can occur to some other part of the machine. The amplitude, oscillation, frequency and/or harmonics of such vibrations and flexing can increase due to a number of factors. For example, the vibrations usually become more pronounced as the distance the extender extends away from the machine turret increases. Other causes of more severe vibration and flexing can occur when the depth of the cut into the work piece is increased, when the rotational speed of the work piece increases, when the cutting tool becomes dull, etc.
To remedy this problem, those skilled in the art have tried using various dampening extenders or adapters which include one or more movable springs and/or pistons positioned in an axial bore formed in such extenders or adapters. These mechanisms have failed to satisfactorily solve the problem. Others have tried using a movable slide positioned between the work piece and the machine turret to decrease the overhang and provide extra support to the extender. These slides do work but are relatively expensive due to their complexity and also require additional time for the machine operator to setup and remove. Still others have tried using an extender that is very long, over 6 feet in length, which extends outward in the opposite direction of the machine turret. The belief is that the opposite end of the extender will compensate for the cantilever portion which supports the cutting tool. However, the use of such a long extender prevents the machine turret from indexing so that another tool, secured thereto, cannot be used when the lengthy extender is mounted to the machine turret. This prevents a finishing tool from completing a precision cut on the work piece until the extender is removed.
Now, a dampening adapter and its method of use have been invented which reduces vibrations and flexing when a cutting tool, mounted thereon, engages a work piece. The new dampening adapter utilizes a large internal 1 so cavity which is filled with a moving pressurized fluid. The quantity and weight of the pressurized fluid, as well as the movement of the pressurized fluid through the cavity, from the machine turret end to the cutting tool end function to dampen vibration and flex forces that are created as the cutting tool engages a work piece.
Briefly, this invention relates to a dampening adapter for mounting a cutting tool onto a machine turret. The dampening adapter includes an elongated housing having a closed first end, a closed second end, and a cavity extending between the first and second ends. The dampening adapter also includes a first attachment mechanism, secured adjacent to the first end, for mounting the dampening adapter onto the machine turret, and a second attachment mechanism, formed in the first end, for mounting the cutting tool. The dampening adapter further includes an inlet port formed through the housing, adjacent to the first end, and an outlet port formed through the second end. Pressurized fluid introduced to the inlet port can be routed through the cavity and be discharged from the outlet port. The pressurized fluid in the cavity facilitates dampening vibrations which can occur as the cutting tool engages a work piece.
A method of using the dampening adapter in a machine having a rotatable chuck and a machine turret is also disclosed. The dampening adapter includes an elongated housing having a closed first end, a closed second end, and a cavity extending between the first and second ends. The dampening adapter also includes a first attachment mechanism secured adjacent to the first end and a second attachment mechanism formed in the first end. The dampening adapter further includes an inlet port formed through the housing, adjacent to the first end, and an outlet port formed through the second end. The method includes the steps of securing a work piece in the rotatable chuck; securing the first attachment mechanism to the machine turret and aligning a pressurized fluid line with the inlet port; securing a cutting tool onto the second attachment mechanism; introducing pressurized fluid to the inlet port which is routed through the cavity and is discharged from the outlet port; positioning the cutting tool to engage the work piece; and engaging the work piece with the cutting tool whereby vibrations which occur can be dampened by the pressurized fluid present in the cavity of the dampening adapter.
The general object of this invention is to provide a dampening adapter for mounting a cutting tool onto a machine turret to reduce vibration and flexing when the cutting tool engages a work piece. A more specific object of this invention is to provide a dampening adapter having an elongated housing with a cavity formed therein which can be filled with a pressurized fluid and the pressurized fluid will reduce vibrations and flexing when the cutting tool engages a work piece.
Another object of this invention is to provide a dampening adapter having an elongated housing with a cavity formed therein which creates a fluid reservoir when a pressurized fluid is introduced into the cavity to thereby increase the weight of the dampening adapter, and reduce vibrations and flexing when the cutting tool engages a work piece.
A further object of this invention is to provide a dampening adapter having a cavity which is void of any moving parts or components.
Still another object of this invention is to provide a method of using the dampening adapter.
Still further, an object of this invention is to provide a method of removing the dampening adapter from a work piece and draining the pressurized fluid from the cavity.
Other objects and advantages of the present invention will become more apparent to those skilled in the art in view of the following description and the accompanying drawings.
Referring to
The work piece 16 can be constructed from any known material and can have an infinite variety of shapes. The dimensions of the work piece 16 can also vary. The material from which the work piece 16 is made can be wood, a metal, ferrous metal, a non-ferrous metal, iron, steel, stainless steel, aluminum, nickel, magnesium, titanium, etc. The material can also be an alloy or be a composite material. Those skilled in the machining arts are aware of the different kinds of materials from which a work piece 16 can be made. By “wood′ it is meant the secondary xylem of trees and shrubs, lying beneath the bark and consisting largely of cellulose and lignin. By “metal” it is meant any of a category of electropositive elements that usually have a shiny surface, are generally good conductors of heat and electricity, and can be melted or fused, hammered into thin sheets, or drawn into wires; an alloy of two or more metallic elements. By “ferrous metal” it is meant of or relating to, or containing iron, especially with valence 2 or a valence lower than a corresponding ferric compound. By non-ferrous meter” it is meant not composed of or containing iron. By “iron” it is meant a lustrous, malleable, ductile, magnetic or magnetizable metallic element occurring abundantly in ores such as hematite and magnetite and used alloyed in a wide range of important structural materials. By steel it is meant a generally hard, strong durable malleable alloy of iron and carbon, usually containing between 0.2 and 1.5 percent carbon, often with other constituents such as manganese, chromium, nickel, or silicon, depending on the desired alloy properties, and widely used as a structural material. By “stainless steel” it is meant any of various steels that are alloyed with at least 10 percent chromium and sometimes containing other elements which are resistant to corrosion and rusting. By “aluminum’ it is meant a silvery-white, ductile metallic element, found chiefly in bauxite. By “nickel” it is meant a silvery hard ductile ferro-magnetic metallic element used in alloys and in corrosion-resistant surfaces and batteries and for electroplating. By “magnesium” it is meant a light metallic element that burns with a brilliant white flame and is used in structural alloys. By “titanium it is meant a strong, low density, highly corrosion-resistant metallic element that occurs widely in igneous rocks and is used to alloy aircraft metals for low weight, strength, and high-temperature stability. By “alloy” it is meant a homogeneous mixture or solid solution of two or more metals, the atoms of one replacing or occupying interstitial positions between the atoms of the other. By “composite” it is meant made up of distinct components; compounds.
Still referring to
The turret 22 is mounted on a shaft 26, which in turn is connected to a drive assembly 28. Normally, the turret 22 is stationary during a machining operation. After a particular tool has performed its intended function, the turret 22 is indexed or incrementally rotated a predetermined number of degrees so that another tool can engage the work piece 16. The drive assembly 28 is movably mounted on one or more guide rails 30. A pair of spaced apart guide rails 30, 30, aligned parallel to one another, can be utilized. Only one guide rail 30 is depicted in
In
The dampening adapter 32 functions to reduce, limit or eliminate vibrations and/or flexing when the cutting tool 34 engages a work piece 16. By “vibration” it is meant the act of vibrating; the condition of being vibrated; a rapid linear motion of a particle or of an elastic solid about an equilibrium position. By “flexing” it is meant to bend repeatedly. During vibrations, a harmonic motion can occur at a certain frequency or oscillation. By “harmonic” it is meant a wave whose frequency is a whole-number multiple of that of another. By “harmonic motion” it is meant a vibration in which the motions are symmetrical about a region of equilibrium. By “frequency” it is meant the property or condition of occurring at frequent intervals; the number of times a specified phenomenon occurs within a specified interval, as the number of repetitions of a complete sequence of values of a periodic function per unit variation of an independent variable or the number of complete cycles of a periodic process occurring per unit time. By “oscillate” it is meant to swing back and forth with a steady uninterrupted rhythm. By “oscillation” it is meant the act or state of oscillating; a single oscillatory cycle.
By reducing, limiting or eliminating such vibrations, one can produce a truer cut, extend the life of the cutting insert and prevent damage to the cutting tool 34 as well as to various parts of the machine 10. One may also be able to increase the depth of the cut, to operate the machine 10 at a higher speed, and to increase the overall efficiency of the cutting process.
Referring to
The dampening adapter 32 can be formed or constructed from any durable material. Typically, the dampening adapter 32 is constructed from metal, iron, steel, stainless steel, a hardened steel, a metal alloy, etc. similar to any other kind of machine tool, boring bar, extenders, etc.
Referring now to
It should be noted that the outside diameter or the maximum cross-sectional dimension of the elongated housing 36 should be equal to or less than about 30% of its length l1. Desirably, the outside diameter or the maximum cross-sectional dimension of the elongated housing 36 is equal to or less than about 25% of its length l1. More desirably, the outside diameter or the maximum cross-sectional dimension of the elongated housing 36 is equal to or less than about 20% of its length l1. Furthermore, when the elongated housing 36 is a tubular member, its outside diameter should be equal to or be less than about 25% of its length 25%. When the elongated housing 36 is a four sided member having a square cross-section, each of the four sides should have a dimension which is less than about 25% of the length l1.
Referring now to
The first and second plates, 44 and 46 respectively, can be secured in place by welding or be secured by one or more mechanical connectors, such as by machine screws. When the first and second plates, 44 and 46 respectively, are secured to the first and second ends, 38 and 40 respectively, of the elongated housing 36, the overall length l of the dampening adapter 32 will be slightly longer than the length l1 of the elongated housing 36. If the first and is second plugs are inserted into the first and second ends, 38 and 40 respectively, of the elongated housing 36, then the overall length l of the dampening adapter 32 will equal the length l of the elongated housing 36.
Referring again to
The volume of the cavity 42 can vary depending on the size of the dampening adapter 32. For a dampening adapter 32 having an overall length l equal to or greater than about 24 inches and a diameter or maximum cross-sectional dimension equal to or greater than about 6 inches, the volume of the cavity 42 should be at least about 4 liters. Desirably, for a dampening adapter 32 having an overall length l equal to or greater than about 24 inches and a diameter or maximum cross-sectional dimension equal to or greater than about 6 inches, the volume of the cavity 42 should be at least about 8 liters, More desirably, for a dampening adapter 32 having an overall length l equal to or greater than about 24 inches and a diameter or maximum cross-sectional dimension equal to or greater than about 6 inches, the volume of the cavity 42 should be at least about 10 liters. Even more desirably, for a dampening adapter 32 having an overall length l equal to or greater than about 24 inches and a diameter or maximum cross-sectional dimension equal to or greater than about 6 inches, the volume of the cavity 42 should be at least about 12 liters.
It should be understood that if the dampening adapter 32 is less than about 12 inches in length, then the cavity 42 will be smaller and the volume of the cavity 42 should be equal to or greater than about 1 liter.
It is very important to understand that the cavity 42 is free or void of any moving parts or components. By component it is meant a constituent element, as of a system; a part of a mechanical or electrical complex. No pistons, piston rods, springs, seals or any other moving parts are positioned in or engage with the cavity 42. The only thing that occupies and moves through the cavity 42 is a pressurized fluid and/or air.
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In
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The second attachment mechanism 50 of the dampening adapter 32 also includes one or more first threaded apertures 82 formed in the lower surface of the slot 80. Four of the first threaded apertures 82, 82, 82 and 82 are depicted in
The second attachment mechanism 50 further includes one or more second threaded apertures 84. Eight of the second threaded apertures 84 are depicted in
Referring now to
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Fluid is introduced to the inlet ports 78, 78 and is routed through the cavity 42 before being discharged from the outlet ports 86, 86. By fluid it is meant a continuous amorphous substance whose molecules move freely past one another and that assumes the shape of its container. Desirably, the fluid is pressurized before is passes through the inlet ports 78, 78. The fluid can be pressurized to any desired pressure value, normally expressed in pounds per square inch (psi). The fluid can have a pressure of from between about 50 psi to about 300 psi. Desirably, the fluid is at a pressure of from between about 80 psi to about 200 psi. More desirably, the fluid is pressurized from between about 100 psi to about 150 psi. Even more desirably, the fluid is at a pressure of at least about 120 psi. The pressurized fluid in the cavity 42 functions to dampen or eliminate vibrations and/or flexing which occur as the cutting tool 34 engages the work piece 16. The pressurized fluid can vary in composition. The pressurized fluid can be a liquid. By liquid it is meant a state of matter characterized by a readiness to flow, little or no tendency to disperse, and relatively high incompressibility. Furthermore, the pressurized fluid can be a semi-fluid. By semi-fluid it is meant intermediate in flow properties between solids and liquids: viscous.
The pressurized fluid can be a cutting fluid coolant used to cool the cutting insert of the cutting tool 34 during machining. Schaeffers Lubricants, having an office in St. Louis, Mo., sells a coolant, model number “HTC iso 68” which works well. Alternatively, the pressurized fluid could be water, an oil, a lubricating oil, a gel, a paste, a gelatin, a jellylike substance, a smooth viscous mixture, a wax, grease, a plastic solid, such as paraffin, a resinous mixture, a cream, a foam, etc. Desirably, the pressurized fluid is a liquid which has a viscosity greater than water. For example, the pressurized fluid can have a viscosity equal to or greater than 0.01 poise measured at a temperature of 25° C. More desirably, the pressurized fluid has a viscosity of at least 0.015 poise at 25° C. Even more desirably, the pressurized fluid has a viscosity of at least 0.02 poise at 25° C. By “viscosity” it is meant the condition or property of being viscous; a numerical measure of the degree to which a fluid resists flow under an applied force.
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress. In everyday terms (and for fluids only), viscosity is “thickness” or “internal friction”. Thus, water is “thin”, having a lower viscosity, while honey is “thick”, having a higher viscosity. Put simply, the less viscous the fluid is, the greater its ease of movement (fluidity).
Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. For example, high-viscosity felsic magma will create a tall, steep stratovolcario, because it cannot flow far before it cools, while low-viscosity mafic lava will create a wide, shallow-sloped shield volcano.
With the exception of superfluids, all real fluids have some resistance to stress and therefore are viscous. A fluid which has no resistance to shear is known as an ideal fluid or inviscid fluid. In common usage, a liquid with the viscosity less than water is known as a mobile liquid, while a substance with a viscosity substantially greater than water is simply called a viscous liquid.
The dynamic viscosity of water is 8.90×10−4 Pa-s or 8.90×10−3 dyn-s/cm2 or 0.890 cP at about 25° C. Water has a viscosity of 0.0091 poise at 25° C. or 1 centipoise at 20° C. By “poise” it is meant a centimeter-gram-second unit of dynamic viscosity equal to one dyne-second per square centimeter.
The pressurized fluid can be at room temperature or be below room temperature. By “room temperature” it is meant an indoor temperature of from 68° F. to 77° F. Desirably, the pressurized fluid is at a temperature below room temperature so that it serves as a coolant for the heat being generated by the cutting process. The temperature of the pressurized fluid can range from between about 35° F. to about 65° F. Desirably, the temperature of the pressurized fluid can range from between about 40° F. to 60° F. More desirably, temperature of the pressurized fluid is less than about 55° F.
The cavity 42 receives the pressurized fluid and fills to its maximum volume. By “volume” it is meant the amount of space occupied by a three-dimensional object or region of space, expressed in cubic units. The volume of the cavity 42 can vary depending upon the size of the dampening adapter 32. The volume of the cavity should be at least about 1 liter. By “liter” it is meant a metric unit of volume equal to approximately 1.056 liquid quarts or 0.264 gallon. By “gallon” it is meant a unit of volume in the U.S. Customary System, used in liquid measure. 1 gallon=4 quarts (3.785 liters). Desirably, the volume of the cavity 42 ranges from between about 2 liters to about 20 liters. More desirably, the volume of the cavity 42 ranges from between about 3 liters to about 15 liters. Even more desirably, the volume of the cavity 42 is at least about 4 liters.
It should be understood that the cavity 42 contains air before the pressurized fluid is introduced through the inlet ports 78, 78. Some air may remain in the cavity 42 when it is filled with the pressurized fluid.
The weight of the pressurized fluid can vary. When the pressurized fluid is a cutting fluid coolant, it can have a weight of from between about 2 to about 5 pounds per liter. The weight of the pressurized fluid, in combination with the weight of the dampening adapter 32, which can exceed 100 pounds, creates a heavy mass which is very effective in dampening any vibrations created as the cutting tool 34 engages the work piece 16. A dampening adapter 32, which has a length l of at least 24 inches, a diameter or cross-sectional dimension of about 6 inches, and a cavity which can handle a volume of about 12 liters, can weigh about 150 pounds or more. The motion of the pressurized fluid appears to add to the dampening effect. The moving pressurized fluid may be more advantageous than using a stationary pressurized fluid in the cavity 42.
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A method of using the dampening adapter 32 in a machine 10 will now be explained. The machine 10 includes a rotatable chuck 14 and a turret 22. The dampening adapter 32 includes an elongated housing 36 having a first end 38, a second end 40, and a cavity 42 extending between the first and second ends, 38 and 40 respectively. The first and second ends, 38 and 40 respectively are closed by first and second plates, 44 and 46 respectively. The dampening adapter 32 also includes a first attachment mechanism 48 secured adjacent to the first end 38, and a second attachment mechanism 50 secured to the second end 40. The dampening adapter 32 further includes an inlet port 78 formed through the elongated housing 36 adjacent to the first end 38, and an outlet port 86 formed through the second end 40. The method includes the steps of securing a work piece 16 in the rotatable chuck 14. The first attachment mechanism 48 is then secured to the turret 22 such that the inlet port 78 is aligned with an incoming pressurized fluid line. The pressurized fluid line functions to direct fluid from a reservoir via a pump to the inlet port 78. The pump pressurizes the fluid to a predetermined psi value. A cutting tool 34 is secured onto the second attachment mechanism 50. Pressurized fluid is then introduced to the inlet port 78 which is routed through the cavity 42 before being discharged from the outlet port 86. The pressurized fluid will eventually fill the volume of the cavity 42. The cutting tool 34 is then positioned to engage the work piece 16. The cutting tool 34 can include a hardened cutting insert that actually contacts the work piece 16 and performs the cut. As the cutting tool 34 engages the work piece 16 and starts cutting, vibrations and/or flexing occur. These vibrations and flexing are dampened and/or eliminated by the pressurized fluid present in and moving through the cavity 42. The volume of the pressurized fluid, in combination with the movement of the pressurized fluid through the cavity 42, and the heavy weight of the dampening adapter 32, dampens out any harmonic motion created by the cutting action. By reducing and/or preventing vibrations and flexing, one can gain process efficiency while assuring that the machine 10 and its various components will not be damaged or destroyed. By minimizing vibrations and flexing, one can possibly run the machine at a higher rpm, make a deeper cut, increase the travel speed of the cutting tool 34, etc.
The method can also include the step of securing a spray nozzle 88 in the outlet port 86 for controlling both the direction and flow pattern of the pressurized fluid onto the cutting tool 34.
Another option is to form a threaded aperture 104 in the elongated housing 36, approximately midway between the first and second ends, 38 and 40 respectively, and then secure a support mechanism 96 into the threaded aperture 104. The attached support mechanism 96 provides an easy way to attach a hook from a hydraulic or pneumatic lift, or from an overhead crane, and facilitate moving the dampening adapter 32 into and out of the machine 10.
The method can further include the step of disengaging the cutting tool 34 from the work piece 16, stopping the flow of pressurized fluid to the inlet port 78, and allowing the pressurized fluid in the cavity 42 to drain out of the cavity 42 via the outlet port 86. With the cavity 42 empty, the dampening adapter 32 can then be unconnected from the machine turret 22 and be removed from the machine 10.
It should be recognized that the dampening adapter 32 is so constructed that the machine turret 22 can be rotatably indexed through a predetermined number of degrees without first requiring the removal of the dampening adapter 32. This is beneficial, for it allows the machine operator to index the machine turret 22 so that other cutting tools can sequentially engage the work piece 16. This speeds up the overall process and makes it economical to use the dampening adapter 32.
While the invention has been described in conjunction with a specific embodiment, it is to be understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.
