Patent Application
20120051857
The present invention relates to a tool assembly for machining a bore.
In at least one embodiment a tool assembly for machining a bore is provided. The tool assembly has a cutting tool and a tool holder. The cutting tool has an abrasive grit disposed continuously around a circumference. The tool holder has a first coolant passage and a secondary coolant passage that extends at an angle from the first coolant passage for spraying coolant toward the cutting tool.
In at least one embodiment a tool assembly for machining a bore is provided. The tool assembly includes a tool holder and a cutting tool disposed on the tool holder. The cutting tool has a first surface, a second surface disposed opposite the first surface, and a third surface extending from the first surface to the second surface that defines a circumference. An abrasive grit is disposed continuously along the circumference. A deflector is disposed on the first surface. The deflector has a deflection surface spaced apart from the first surface for deflecting coolant toward the third surface.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
Referring to
The system 10 may include a spindle 20 and a tool assembly 22. The spindle 20 may be configured to receive the tool assembly 22 and rotate about an axis of rotation 24. The spindle 20 may be driven by a motor and may be disposed on a computer numerically controlled (CNC) machine that may position the tool assembly 22 along multiple axes in a three dimensional space. A coolant source 26 may be associated with the spindle 20 and may be configured to provide pressurized coolant through the spindle 20 to the tool assembly 22 in a manner known by those skilled in the art.
The tool assembly 22 may include a tool holder 30 and a cutting tool 32. The tool holder 30, which may also be called an arbor or a mandrel, may have a generally cylindrical configuration. A first end of the tool holder 30 may be configured to be mounted to the spindle 20. A second end of the tool holder 30 disposed opposite the first end may be configured to receive the cutting tool 32. For instance, the tool holder 30 may include one or more holes 34 that may receive a fastener like a screw to couple the cutting tool 32 to a second end of the tool holder 30. In addition, the tool holder 30 may include one or more coolant passages that receive coolant via the spindle 20 as will be discussed in more detail below.
The cutting tool 32 may include a body 40 and an abrasive grit 42. The body 40 may have a generally cylindrical configuration that may include a first surface 44 and a second surface 46 disposed opposite the first surface 44. A third surface 48 may extend from the first surface 44 to the second surface 46. The third surface 48 may be disposed along a circumference of the body 40. A radius or area of curvature may be provided where the third surface 48 intersects the first surface 44 and/or the second surface 46 to facilitate positioning of the cutting tool 32 into or out of a bore 14. One or more mounting holes 50 may be provided on the body 40 that extend from the first surface 44 to the second surface 46 for receiving a fastener for coupling the cutting tool 32 to the tool holder 30.
The abrasive grit 42 may be disposed on the third surface 48 and may extend continuously around the circumference of the body 40. The abrasive grit 42 may not be disposed on the first and second surfaces 44, 46 in one or more embodiments. The abrasive grit 42 may include a plurality of abrasive particles or grains for removing material from the workpiece 12. For example, the abrasive grit 42 may be electroplated on to a metal disk, or formed into a vitrified bond wheel in one or more embodiments.
Referring to
The tool holder 30′ may include a first coolant passage 60 that receives coolant from the coolant source 26 via the spindle 20. The first coolant passage 60 may supply coolant to one or more secondary coolant passages 62 in the tool holder 30′ and to the cutting tool 32′. The first coolant passage may be disposed along the axis of rotation 24.
The secondary coolant passages 62 may extend from the first coolant passage 60 to an external surface of the tool holder 30′. The secondary coolant passages 62 may be disposed at an angle with respect to the first coolant passage 60 and/or the axis of rotation 24. More specifically, the secondary coolant passages 62 may extend at an angle from the first coolant passage 60 toward the cutting tool 32′, such as toward a location where the second and third surfaces 46, 48 intersect.
The secondary coolant passages 62 may have a linear configuration, a non-linear configuration, or a combination thereof. In
In
Referring again to
The secondary tool coolant passages 82 may have a linear configuration, a non-linear configuration, or a combination thereof. In
In
Referring to
The legs 102 may facilitate mounting of the deflector 100 to the first surface 44. The legs 102 may be spaced apart from each other to provide openings 106 through which coolant may pass.
The deflection surface 104 may be configured to redirect coolant exiting the first tool coolant passage 80′ outwardly toward the third surface 48 and the abrasive grit 42. The deflection surface 104 may face toward and may be spaced apart from the first surface 44. In addition, the deflection surface 104 may include a deflection feature 108 to help redirect coolant. For example, the deflection feature 108 may be centered above the first tool coolant passage 80′ and may have a conical configuration that extends from toward the first surface 44 of the cutting tool 32′″.
Referring to
At 200, the method may position the tool assembly at an initial position. The initial position may be located along a center axis of a bore and proximate a first end of the bore or bore opening. As such, the cutting tool may not initially engage the workpiece 12. In addition, the tool assembly may be rotated about the axis of rotation 24 by the spindle 20 at any suitable speed, such as between 1000 and 1500 revolutions per minute.
At 202, the system 10 may move tool assembly along a helical tool feed path. The cutting tool may be moved laterally such that the abrasive grit 42 engages a surface of the cylinder bore 14. Then the cutting tool may be moved around the inside diameter of the cylinder bore 14 while being advanced along the length of the cylinder bore 14. As such, the abrasive grit 42 may abrasively remove material from the inside of the cylinder bore as it travels around and along the length of the cylinder bore. The helical path may be determined by a helical interpolation algorithm that may be computed by the CNC machine or provided as a sequence of positioning coordinates. The helical path may be configured such that the abrasive grit 42 travels across or engages the entire surface of the cylinder bore 14.
The helical tool path may also be configured to remove material from a tapered bore that is narrower at one end than another. Such a tool path may be executed by altering the distance the tool assembly moves relative to the center of the bore as it travels along the length of the bore. For instance, the tool may be moved in nominally larger spirals as the bore narrows to compensate for tool bending.
At 204, the tool assembly may execute an optional second pass. A second pass may help provide more uniform bore dimensions. A second path may be executed by following the helical cutting path backwards toward the initial position, thereby executing a “reverse cut” of the bore. If a second pass is not executed, the tool assembly may be moved to a position where it does not contact the bore surface and then retracted out of the bore.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
